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  • 1.
    Dai, Jingjing
    et al.
    Southwest Jiaotong Univ, Key Lab Adv Technol Mat, Minist Educ, Chengdu 610031, Sichuan, Peoples R China..
    Hu, Qingdan
    Southwest Jiaotong Univ, Key Lab Adv Technol Mat, Minist Educ, Chengdu 610031, Sichuan, Peoples R China..
    Sun, Weiwei
    Southeast Univ, SEU FEI Nanop Ctr, Key Lab MEMS, Minist Educ, Nanjing 210096, Peoples R China..
    Hu, Chunfeng
    Southwest Jiaotong Univ, Key Lab Adv Technol Mat, Minist Educ, Chengdu 610031, Sichuan, Peoples R China..
    Oppeneer, Peter M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Feng, Qingguo
    Southwest Jiaotong Univ, Key Lab Adv Technol Mat, Minist Educ, Chengdu 610031, Sichuan, Peoples R China..
    Behavior of intrinsic defects in BaF2 under uniaxial compressions: An ab initio investigation2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102730Article in journal (Refereed)
    Abstract [en]

    We revisit the defects and related optical properties of one of the prototypical scintillator materials, BaF2, by means of density functional theory calculations. The interstitial F atom is found to be the most favorable defect to be formed, while it is rather difficult to create a F vacancy, Ba vacancy and Ba interstitial intrinsically, unless external forces are applied to the lattice, such as shock compression. The migration barriers for the above defects are remarkably path dependent. For a Ba vacancy, the migration barrier in the (001) (loading) direction is significantly reduced compared to those in the perpendicular (100) and (010) directions, while the migration along the (101) direction has the least value, which is surprisingly smaller than that at ambient pressure. An interstitial Ba atom prefers to move along the (100) and (010) directions in a manner similar to collective diffusion. The F vacancy has the lowest energy barrier along the (001) direction, while uniaxial strain greatly hinders the diffusion of F interstitials. We also study the role of defects on the optical absorption and find that a F vacancy, and interstitial F and Ba atoms are able to introduce pronounced changes to the spectra, whereas the Ba vacancy only shows marginal effects. The favorable migration paths for the different types of defects under strain or pressure can contribute to the design of specific ionic conductor properties under extreme conditions.

  • 2.
    Dewi, Handika Sandra
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Volpp, Jörg
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander F.H.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Influence of secondary-pass laser treatment on retained ferrite and martensite in 44MnSiVS6 microalloyed steel2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103282Article in journal (Refereed)
    Abstract [en]

    Overlapping regions of laser surface treatment are necessary features when processing large surface areas or cylindrical specimens. However, complex microstructural changes that appear in the regions with multiple heat treatment can affect their mechanical properties. Therefore, this study focuses on examining thermal cycle characteristics and resulting microstructures, particularly martensite and retained ferrite structures, to better understand the correlation between experienced thermal cycles and resulting microstructures. Laser surface hardening experiments on 44MnSiVS6 microalloyed steels together with thermal diffusion simulations were conducted to relate microstructures after the secondary pass of the laser treatment to the local thermal cycles experienced during the process. The amount of retained ferrite was calculated and compared to the respective thermal cycle characteristics. Regions which experienced thermal cycles below Ac3 temperature showed microstructures similar to those after tempering. The sizes of retained ferrite structures were found to decrease as the total holding time increases regardless of how the holding time is distributed in multiple laser treatments. However, the size of retained ferrite structures were constant in the region where tempering effect occurred. This shows that the amount of retained ferrite can be tailored by modifying the experienced total holding time and a reduction of retained ferrite structure happens only if the secondary thermal cycle is above Ac3 temperature.

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  • 3.
    Dobrota, Ana S.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Vlahovic, Jovana
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;Univ Antwerp, Dept Phys, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pašti, Igor
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    First-principles analysis of aluminium interaction with nitrogen-doped graphene nanoribbons: From adatom bonding to various2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103388Article in journal (Refereed)
    Abstract [en]

    Enhancing aluminium interaction with graphene-based materials is of crucial importance for the development of Al-storage materials and novel functional materials via atomically precise doping. Here, DFT calculations are employed to investigate Al interactions with non-doped and N-doped graphene nanoribbons (GNRs) and address the impact of the edge sites and N-containing defects on the material's reactivity towards Al. The presence of edges does not influence the energetics of Al adsorption significantly (compared to pristine graphene sheet). On the other hand, N-doping of graphene nanoribbons is found to affect the adsorption energy of Al to an extent that strongly depends on the type of N-containing defect. The introduction of edge-NO group and doping with in -plane pyridinic N result in Al adsorption nearly twice as strong as on pristine graphene. Moreover, double n-type doping via N and Al significantly alters the electronic structure of Al,N-containing GNRs. Our results suggest that selectively doped GNRs with pyridinic N can have enhanced Al-storage capacity and could be potentially used for selective Al electrosorption and removal. On the other hand, Al,N-containing GNRs with pyridinic N could also be used in resistive sensors for mechanical deformation. Namely, strain along the longitudinal axis of these dual doped GNRs does not affect the binding of Al but tunes the bandgap and causes more than 700-fold change in the conductivity. Thus, careful defect engineering and selective doping of GNRs with N (and Al) could lead to novel multifunctional materials with exceptional properties. [GRAPHICS]

  • 4.
    Fedina, Tatiana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Sundqvist, Jesper
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander F.H.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Spattering and oxidation phenomena during recycling of low alloy steel powder in Laser Powder Bed Fusion2021In: Materials Today Communications, ISSN 2352-4928, Vol. 27, article id 102241Article in journal (Refereed)
    Abstract [en]

    This study reports on the impact of repeated powder recycling on the degradation of low alloy steel powder in Laser Powder Bed Fusion. The average powder particle size increased slightly upon recycling due to powder agglomeration and the presence of spatters and other ejecta from the process zone. The oxygen content showed a continuous growth after each recycle, while the other chemical elements of the recycled powder remained largely unchanged. A map of ejecta classification is presented, featuring various ejecta types formed during laser processing. Ejecta of increased diameter and different shapes were observed in the recycled powder, using high-speed imaging and Scanning Electron Microscopy. The ejecta were collected after each powder recycle to enable the calculation of the ejecta mass generated during the process. The result showed a direct correlation between oxygen content in the powder and spatter/ejecta formation with the number of recycling events. It is likely that the increase in oxygen contributes to powder spattering.

  • 5.
    Flygare, Mattias
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Svensson, Krister
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Quantifying crystallinity in carbon nanotubes and its influence on mechanical behaviour2019In: Materials Today Communications, ISSN 2352-4928, Vol. 18, p. 39-45Article in journal (Refereed)
    Abstract [en]

    The different fabrication methods that have been developed for making carbon nanotubes will provide materials with different levels of crystallinity. As crystallinity is qualitatively known to have a profound influence on material properties, this raises the need for standardised quantitative analysis. Here we show how transmission electron microscopy can be used to provide quantitative information about effective crystallite sizes in individual nanotubes which we link to the mechanical behaviour of the tubes. The method relies on a thorough analysis of diffraction patterns and a careful extraction of instrumental and sample contributions to the peak shapes. We find that arc-discharge grown tubes have crystallite sizes that are comparable to the circumference of the outer tube walls, while commercial catalytically grown tubes have much smaller crystallites implying that each cylindrical nanotube wall can be thought of as a patchwork of small graphene-like grains. The clear differences in crystallite sizes are then compared to known differences in mechanical behaviour, such as a substantial disparity in stiffness and significantly different behaviours under bending stress.

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  • 6.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gambino, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    High thermoelectric power factor of pure and vanadium-alloyed chromium nitride thin films2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102493Article in journal (Refereed)
    Abstract [en]

    Chromium-nitride based materials have shown unexpected promise as thermo-electric materials for, e.g., wasteheat harvesting. Here, CrN and (Cr,V)N thin films were deposited by reactive magnetron sputtering. Thermoelectric measurements of pure CrN thin films show a low electrical resistivity between 1.2 and 1.5 x 10(-3) Omega cm and very high values of the Seebeck coefficient and thermoelectric power factor, in the range between 370-430 mu V/K and 9-11 x 10(-3) W/mK(2), respectively. Alloying of CrN films with small amounts (less than 15 %) of vanadium results in cubic (Cr,V)N thin films. Vanadium decreases the electrical resistivity and yields powerfactor values in the same range as pure CrN. Density functional theory calculations of sub-stoichiometric CrN1-delta and (Cr,V)N1-delta show that nitrogen vacancies and vanadium substitution both cause n-type conductivity and features in the band structure typically correlated with a high Seebeck coefficient. The results suggest that slight variations in nitrogen and vanadium content affect the power factor and offers a means of tailoring the power factor and thermoelectric figure of merit.

  • 7.
    Habibi, M.
    et al.
    Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.
    Mirzaei, S.
    CEITEC BUT, Brno University of Technology, Brno, Czech Republic.
    Arman, A.
    ACECR, Vacuum Technology Research Group, Sharif University Branch, Tehran, Iran.
    Jurečka, S.
    Institute of Aurel Stodola, Faculty of Electrical Engineering, University of Žilina, Liptovský Mikuláš, Slovakia.
    Sadeghi, Mohammad
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zelati, A.
    Department of Basic Sciences, Birjand University of Technology, Birjand, Iran.
    Shakoury, R.
    Department of Physics, Faculty of Science, Imam Khomeini International University, Qazvin, Iran.
    Tanhaee, E.
    Department of Nanophysics, Tehran University & Iranian National Center for Laser Science and Technology, Tehran, Iran.
    Ghobadi, N.
    Department of Physics, Faculty of Science, Malayer University, Malayer, Iran.
    Ehteram, H.
    ACECR, Vacuum Technology Research Group, Sharif University Branch, Tehran, Iran.
    Ţălu, S.
    The Directorate of Research, Development and Innovation Management (DMCDI), Technical University of Cluj-Napoca, Cluj-Napoca, Romania.
    Microstructure, fractal geometry and corrosion properties of CrN thin films: The effect of shot number and angular position2022In: Materials Today Communications, ISSN 2352-4928, Vol. 32, article id 104072Article in journal (Refereed)
    Abstract [en]

    The effect of different plasma focus shots and angular positions (0° and 30°) on the properties of chromium nitride (CrN) coatings, deposited by a plasma focus (PF) device on stainless steel substrates, have been systematically investigated in this paper. The structural and morphological properties of CrN thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). Moreover, the corrosion behavior of the CrN thin films was investigated using the ‘c’ method. The XRD patterns demonstrated the growth of the polycrystalline structure composed of CrN/Cr2N nanograins and the enhanced crystallinity of the CrN coatings upon increasing the shot numbers. In addition, AFM results showed enhanced multifractal properties of the sample prepared at 0° angular position and a reducing trend in these properties for the layers prepared at 30° angular position. Moreover, they exhibited sharp hillock-like features on the surface, corresponding to the columnar growth of the CrN coatings, which further protruded as the number of shots increased. The results of the corrosion test showed that the resistance of stainless-steel substrate was improved by depositing the CrN coatings due to the formation of a passive and protective layer on its surface. Notably, ceramic CrN film, prepared through 10 shots at 30° angular position, showed the best corrosion resistance. Our strategy is advantageous for designing and manufacturing novel devices and instruments based on CrN corrosion resistant coating.

  • 8.
    He, Shuang
    et al.
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Tan, Qiankun
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Chen, Xu
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Liu, Ye
    School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
    Gorbatov, Oleg I.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Peng, Ping
    School of Materials Science and Engineering, Hunan University, Changsha 410082, China.
    First-principles study of Re-W interactions and their effects on the mechanical properties of γ/γ' interface in Ni-based single-crystal alloys2023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106662Article in journal (Refereed)
    Abstract [en]

    The distribution of solutes and their interactions play a crucial role in determining the mechanical properties of the γ/γ′ interface in Ni-based single-crystal alloys. In this study, atomic interactions between Re and W and their alloying effects on the inter-phase cohesion of the γ/γ′ interface are investigated by first-principles calculations. Our results show that W atom exhibits a preference for partitioning into the γ phase, while the stability of the γ/γ′ interface can be enhanced due to the partitioning of W to the γ′ phase. Moreover, our results reveal that partitioned W atoms in the γ′ phase contribute to the strengthening of the γ/γ′ interface. Conversely, the dissolution of W atoms in the γ phase weakens the inter-phase cohesion. However, this detrimental effect can be mitigated by introducing of Re into the γ/γ′ interface. Partitioning of Re and W into separate phases yields minimal alterations in interaction energies, resulting in a notable enhancement of inter-phase cohesion when compared to the partitioning of Re and W within γ phase of the γ/γ′ interface. Additionally, the partitioning of solute atoms at the γ/γ′ interface leads to local lattice distortion and interfacial energy reduction, which contribute to the enhancement of inter-phase cohesion of the γ/γ′ interface. As a result, a model is proposed for interpretation of crack propagation at the γ/γ′ interface at the threshold region with the presence of tensile stress in Ni-based single-crystal alloys.

  • 9.
    Holmberg, Jonas
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. RISE IVF AB, Argongatan 30, Mölndal, 431 53, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Trollhättan, 461 81, Sweden.
    Berglund, Johan
    RISE IVF AB, Argongatan 30, Mölndal, 431 53, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth2020In: Materials Today Communications, ISSN 2352-4928, Vol. 24, article id 100958Article in journal (Refereed)
    Abstract [en]

    Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth. © 2020 The Authors

  • 10.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Beno, Tomas
    University West, Sweden.
    A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth2020In: Materials Today Communications, ISSN 2352-4928, Vol. 24, article id 100958Article in journal (Refereed)
    Abstract [en]

    Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth.

  • 11.
    Hosseini, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Forouzan, Farnoosh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vuorinen, Esa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    In-situ microstructural evolution during quenching and partitioning of a high-carbon steel by high-temperature X-Ray diffraction2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103503Article in journal (Refereed)
    Abstract [en]

    Carbon partitioning from martensite to austenite is essential for austenite stabilization during quenching and partitioning (Q&P), while a few competitive phenomena, such as bainitic transformation and carbide precipitation, alter the microstructural evolution. So, there is a need of using in-situ in combination with ex-situ characterisation techniques to understand the C partitioning at high temperature in relation to simultaneous competitive phenomena that might occur during the partitioning stage.

    In this study, microstructural evolutions of a medium carbon steel ( 0.6C–1.6Si–1.25Mn–1.75Cr wt%) during Q&P treatment were investigated by using an in-situ High-Temperature X-Ray Diffraction (HTXRD) equipment at three partitioning temperatures. Results confirmed that carbon enrichment of austenite at 280 and 400 ℃ originates from partial carbon depletion from martensite and bainitic transformation, while partitioning at 500 ℃ results in the complete depletion of carbon from initial martensite and ferrite formation. Short diffusion distance (~0.13 µm) of carbon at 280 ℃ caused a poor carbon homogenization of austenite and formation of 8 vol% fresh martensite after final quenching. High Si content of the steel stabilized transitional carbides and, concurrently, suppressed Fe3C formation during Q&P. The outcome of this study could contribute to the design of suitable chemistry and process parameters for producing quenched and partitioned steels.

  • 12.
    Huang, He
    et al.
    Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China.;Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Wang, Xin
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Shi, Jie
    Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China..
    Huang, Huogen
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Zhao, Yawen
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Xu, Haiyan
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Zhang, Pengguo
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Long, Zhong
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Bai, Bin
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Fa, Tao
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Ma, Ce
    Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China..
    Li, Fangfang
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Meng, Daqiao
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Li, Xiaoqing
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Schonecker, Stephan
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.;Dept Phys & Astron, Div Mat Theory, SE-75120 Uppsala, Sweden.;Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Material informatics for uranium-bearing equiatomic disordered solid solution alloys2021In: Materials Today Communications, ISSN 2352-4928, Vol. 29, article id 102960Article in journal (Refereed)
    Abstract [en]

    Near-equiatomic, multi-component alloys with disordered solid solution phase (DSSP) are associated with outstanding performance in phase stability, mechanical properties and irradiation resistance, and may provide a feasible solution for developing novel uranium-based alloys with better fuel capacity. In this work, we build a machine learning (ML) model of disordered solid solution alloys (DSSAs) based on about 6000 known multicomponent alloys and several materials descriptors to efficiently predict the DSSAs formation ability. To fully optimize the ML model, we develop a multi-algorithm cross-verification approach in combination with the SHapley Additive exPlanations value (SHAP value). We find that the Delta S-C, Lambda, Phi(s), gamma and 1/Omega, corresponding to the former two Hume - Rothery (H - R) rules, are the most important materials descriptors affecting DSSAs formation ability. When the ML model is applied to the 375 uranium-bearing DSSAs, 190 of them are predicted to be the DSSAs never known before. 20 of these alloys were randomly synthesized and characterized. Our predictions are in-line with experiments with 3 inconsistent cases, suggesting that our strategy offers a fast and accurate way to predict novel multi-component alloys with high DSSAs formation ability. These findings shed considerable light on the mapping between the material descriptors and DSSAs formation ability.

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  • 13.
    Huang, He
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China..
    Wang, Xin
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Shi, Jie
    Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China..
    Huang, Huogen
    Zhao, Yawen
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Xu, Haiyan
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Zhang, Pengguo
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Long, Zhong
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Bai, Bin
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Fa, Tao
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Ma, Ce
    Sci & Technol Surface Phys & Chem Lab, Mianyang 621907, Sichuan, Peoples R China..
    Li, Fangfang
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Meng, Daqiao
    China Acad Engn Phys, Inst Mat, Mianyang 621900, Sichuan, Peoples R China..
    Li, Xiaoqing
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Schönecker, Stephan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Dept Phys & Astron, Div Mat Theory, SE-75120 Uppsala, Sweden.;Wigner Res Ctr Phys, Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Material informatics for uranium-bearing equiatomic disordered solid solution alloys2021In: Materials Today Communications, ISSN 2352-4928, Vol. 29, article id 102960Article in journal (Refereed)
    Abstract [en]

    Near-equiatomic, multi-component alloys with disordered solid solution phase (DSSP) are associated with outstanding performance in phase stability, mechanical properties and irradiation resistance, and may provide a feasible solution for developing novel uranium-based alloys with better fuel capacity. In this work, we build a machine learning (ML) model of disordered solid solution alloys (DSSAs) based on about 6000 known multicomponent alloys and several materials descriptors to efficiently predict the DSSAs formation ability. To fully optimize the ML model, we develop a multi-algorithm cross-verification approach in combination with the SHapley Additive exPlanations value (SHAP value). We find that the Delta S-C, Lambda, Phi(s), gamma and 1/Omega, corresponding to the former two Hume - Rothery (H - R) rules, are the most important materials descriptors affecting DSSAs formation ability. When the ML model is applied to the 375 uranium-bearing DSSAs, 190 of them are predicted to be the DSSAs never known before. 20 of these alloys were randomly synthesized and characterized. Our predictions are in-line with experiments with 3 inconsistent cases, suggesting that our strategy offers a fast and accurate way to predict novel multi-component alloys with high DSSAs formation ability. These findings shed considerable light on the mapping between the material descriptors and DSSAs formation ability.

  • 14.
    Jafarpour, Mohammad
    et al.
    Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey.;Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey..
    Aghdam, Araz Sheibani
    Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey.;Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey..
    Kosar, Ali
    Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey.;Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey.;Sabanci Univ, Ctr Excellence Funct Surfaces & Interfaces Nanodi, TR-34956 Istanbul, Turkey..
    Cebeci, Fevzi cakmak
    Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey.;Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey..
    Ghorbani, Morteza
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging. Sabanci Univ, Nanotechnol Res & Applicat Ctr, TR-34956 Istanbul, Turkey.;Sabanci Univ, Ctr Excellence Funct Surfaces & Interfaces Nanodi, TR-34956 Istanbul, Turkey..
    Electrospinning of ternary composite of PMMA-PEG-SiO2 nanoparticles: Comprehensive process optimization and electrospun properties2021In: Materials Today Communications, ISSN 2352-4928, Vol. 29, article id 102865Article in journal (Refereed)
    Abstract [en]

    Electrospinning has been realized to be a promising method for creating nano-composite fibers due to its significant growth for producing innovative composites with advanced applications. In this method a polymeric solution subjected to an electrohydrodynamic process and slim charged liquid jet is formed inside a high potential electric field. The high voltage enables the production of continuously long fibers on a collector surface. Addition of different polymers and NPs to the one-component solution to modify the physicochemical characteristic and decorating the surface of electrospun fibers has proven to be challenging and imperative for many fields especially novel bioengineering and filtration applications. In this study, the effects of major parameters on the fabrication of electrospun fibers were extensively investigated. At the first step, formation of nanofibers on the surface of collector and optimization of process parameters were determined based on the mean diameter of resulting fibers, through SEM (Scanning Electron Microscopy) images. The optimum values for concentration, applied voltage, the distance between the tip of needle and collector, and flow rate determined to be 10 wt%, 12 kV, 20 cm, and 0.6 mL h(-1), respectively. Afterwards, the hydrophilicity of fibers was modified by adding different poly (ethylene glycol) (PEG) concentrations (20, 30, and 40 wt%) to the polymeric solution. The contact angle analysis revealed that the poly (methyl methacrylate) (PMMA) and 30 wt% PEG fabricated fibrous mat exhibited a better wettability and 71.61% lower hydrophobicity compared to pure PMMA electrospun mats. In the next step, silica NPs (nanoparticles) were introduced to the polymeric solution of electrospinning in the form of an IPA (isopropanol)-based collide solution. The dispersed solution-based addition of silica NPs prevented the aggregation state of NPs in the nanofibers. The addition of silica nanoparticles also changed the thermal and mechanical properties of the ternary composite, which were analyzed in TGA (thermogravimetric analysis) and tensile tests. Noteworthy, the addition of 30% PEG and silica NPs increase 3 times the tensile strength and around 2 times elongation in comparison with pure PMMA electrospun mats. These results highlight that the hybrid composite leads to a promising new electrospun mat for filtration and bioengineering applications.

  • 15. Khelidj, H.
    et al.
    Portavoce, A.
    Bertoglio, M.
    Descoins, M.
    Patout, L.
    Hoummada, K.
    Hallén, Anders
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems, Electronic and embedded systems.
    Charaï, A.
    Benoudia, M. C.
    Mangelinck, D.
    Ge(Sn) growth on Si(001) by magnetron sputtering2021In: Materials Today Communications, ISSN 2352-4928, Vol. 26, article id 101915Article in journal (Refereed)
    Abstract [en]

    The semi-conductor Ge1―xSnx exhibits interesting properties for optoelectronic applications. In particular, Ge1―xSnx alloys with x ≥ 0.1 exhibit a direct band-gap, and integrated in complementary-metal-oxide-semiconductor (CMOS) technology, should allow the development of Si photonics. CMOS-compatible magnetron sputtering deposition was shown to produce monocrystalline Ge1―xSnx films with good electrical properties at low cost. However, these layers were grown at low temperature (< 430 K) and contained less than 6 % of Sn. In this work, Ge1―xSnx thin films were elaborated at higher temperature (> 600 K) on Si(001) by magnetron sputtering in order to produce low-cost and CMOS-compatible relaxed pseudo-coherent layers with x ≥ 0.1 exhibiting a better crystallinity. Ge1―xSnx crystallization and Ge1―xSnx crystal growth were investigated. Crystallization of an amorphous Ge1―xSnx layer deposited on Si(001) or Ge(001) grown on Si(001) leads to the growth of polycrystalline films. Furthermore, the competition between Ge/Sn phase separation and Ge1―xSnx growth prevents the formation of large-grain Sn-rich Ge1―xSnx layers without the formation of β-Sn islands on the layer surface, due to significant atomic redistribution kinetics at the crystallization temperature (T = 733 K for x = 0.17). However, the growth at T = 633 K of a highly-relaxed pseudo-coherent Ge0.9Sn0.1 film with low impurity concentrations (< 2 × 1019 at cm―3) and an electrical resistivity four orders of magnitude smaller than undoped Ge is demonstrated. Consequently, magnetron sputtering appears as an interesting technique for the integration of optoelectronic and photonic devices based on Ge1―xSnx layers in the CMOS technology.

  • 16.
    Khorshidi, H.
    et al.
    Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran..
    Kermanpur, A.
    Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran..
    Rastegari, H.
    Birjand Univ Technol, Dept Mech & Mat Engn, South Khorasan 9719866981, Iran..
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Somani, M. C.
    Univ Oulu, Ctr Adv Steels Res, POB 4200, Oulu 90014, Finland..
    Design of a hot deformation processing map for a Ni-free, N-bearing austenitic stainless steel2021In: Materials Today Communications, ISSN 2352-4928, Vol. 27, article id 102352Article in journal (Refereed)
    Abstract [en]

    The hot deformation characteristics of a FeCrMnN austenitic stainless steel containing 0.28 wt.% nitrogen (N) was investigated by hot compression tests using a Gleeble simulator in the temperature range of 800-1200 degrees C and at constant true strain rates of 0.01-10 s(-1) with all specimens deformed to similar to 0.9 true strain. The influence of deformation conditions on microstructural mechanisms and phase transformations was characterized. A processing map based on dynamic materials modelling (DMM) was designed and interpreted for predicting the domain of stable flow for safe, defect-free hot deformation. The results revealed the occurrence of dynamic recrystallization (DRX) in a domain extending over the temperature and strain rate ranges of 1100-1200 degrees C and 0.1-1 s(-1), respectively, with the efficiency of power dissipation (eta) of 45-55 %. Decreasing temperature and increasing strain rate led to a reduction in DRX grain size following microstructural reconstitution. Another small deterministic domain of 820-1000 degrees C and 0.01-0.05 s(-1) was identified showing occurrence of partial DRX in shear bands leading to formation of a mixed microstructure. The instability criteria delineated the regime of unstable flow covering a large part of the processing map extending over low temperatures (800-950 degrees C) and high strain rates (0.1-10 s(-1)) that must be avoided during processing.

  • 17. Khrapov, D.
    et al.
    Kozadayeva, M.
    Koptyug, Andrey
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Mishurova, T.
    Meinel, D.
    Surmenev, R.
    Surmeneva, M.
    Geometrical features and mechanical properties of the sheet-based gyroid scaffolds with functionally graded porosity manufactured by electron beam melting2023In: Materials Today Communications, ISSN 2352-4928, Vol. 35, article id 106410Article in journal (Refereed)
    Abstract [en]

    Functionally graded porous scaffolds (FGPS) constructed with pores of different size arranged as spatially continuous structure based on sheet-based gyroid with three different scaling factors of 0.05, 0.1 and 0.2 were produced by electron beam powder bed fusion. The pore dimensions of the obtained scaffolds satisfy the values required for optimal bone tissue ingrowth. Agglomerates of residual powder were found inside all structures, which required post-manufacturing treatment. Using X-ray Computed Tomography powder agglomerations were visualized and average wall thickness, wall-to-wall distances, micro- and macro-porosities were evaluated. The initial cleaning by powder recovery system (PRS) was insufficient for complete powder removal. Additional treatment by dry ultrasonic vibration (USV) was applied and was found successful for gyroids with the scaling factors of 0.05 and 0.1. Mechanical properties of the samples, including quasi-elastic gradients and first maximum compressive strengths of the structures before and after USV were evaluated to prove that additional treatment does not produce structural damage. The estimated quasi-elastic gradients for gyroids with different scaling factors lie in a range between 2.5 and 2.9 GPa, while the first maximum compressive strength vary from 52.5 for to 59.8 MPa, compressive offset stress vary from 46.2 for to 53.2 MPa. 

  • 18.
    Lamelas, Victor
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Tian, Liyun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bonvalet-Rolland, Manon
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures. UMET, Unité Matériaux et Transformations, Université de Lille, CNRS, INRAe, Centrale Lille, UMR 8207, 59000, Lille, France.
    Walbrühl, M.
    AB Sandvik Coromant R&D, Lerkrogsvägen 19, SE-126 80 Stockholm, Sweden.
    Lizarrága, Raquel
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Modeling of the intrinsic softening of γ-carbides in cemented carbides2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107454Article in journal (Refereed)
    Abstract [en]

    Cemented carbides are widely used materials in industrial applications due to their remarkable combination of hardness and toughness. However, they are exposed to high temperatures during service leading to a reduction of their hardness. A common practice to damp this softening is to incorporate transition metal carbides in cemented carbide compositions, which keeps the hardness relatively higher when temperature increases. Understanding the underlying mechanisms of this softening is crucial for the development of cemented carbides with optimal properties. In this work, atomic-scale mechanisms taking place during plastic deformation are analyzed and linked to the effect that they have on the intrinsic macro-scale softening of the most common TMC used in cemented carbides grades (TiC, ZrC, HfC, VC, NbC and TaC). The proposed model uses the generalized stacking fault energy obtained from density functional theory calculations as an input to Peierls-Nabarro analytical models to obtain the critically resolved shear stress needed for deformation to occur in different slip systems. Subsequently, this information is used to predict the hardness variation across the temperature service range experienced by cemented carbides in wear applications. In addition to the prediction of hot-hardness for TMC, the obtained results also offer valuable insights into the intrinsic mechanisms governing TMCs deformation. The results facilitate the identification of dominant dislocation types influencing plasticity within distinct temperature regimes, define energetically favorable slip systems, and predict the brittle-ductile transition temperature in these materials. For instance, for group IV carbides at low temperatures, the slip system with a lower GSFE is {110}<11̅0> and around 30% of their melting temperature, the GSFE of partial slip in {111}<12̅1> becomes lower, changing the dominant slip mechanism and characterizing the Brittle-Ductile transition.

  • 19.
    Li, Xinmin
    et al.
    Shanghai Univ, Sch Mechatron Engn & Automat, Shanghai 200444, Peoples R China..
    Zhang, Runzhi
    Shanghai Univ, Sch Mechatron Engn & Automat, Shanghai 200444, Peoples R China..
    Liu, Zibo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Tsinghua Univ, Dept Mech Engn, State Key Lab Tribol Adv Equipment SKLT, Beijing 100084, Peoples R China..
    Pu, Yifan
    Shanghai Univ, Sch Mechatron Engn & Automat, Shanghai 200444, Peoples R China..
    Molecular dynamics study on friction of the iron-aluminum alloy2022In: Materials Today Communications, ISSN 2352-4928, Vol. 33, p. 104402-, article id 104402Article in journal (Refereed)
    Abstract [en]

    Iron-aluminum alloy has been widely used in aerospace, nuclear power, electronics and other fields. Taking into account the limitations of the continuum mechanics model at the microscopic scale, it is critical to use nanoscale simulation methods like molecular dynamics (MD) to have a deeper understanding of the friction and wear behavior. Through MD simulation, this thesis mainly studied the friction and wear process of iron aluminum alloy under different conditions. The main conclusions are as follows:(1) The frictional force first experiences a period of growth, and then stabilizes with some fluctuations due to the release of stress-energy caused by deformation.(2) Temperature and friction speed has no significant effect on friction force.(3) The higher the friction speed is, the more wear debris it produces, and the more severely the material is damaged.(4) The force and coefficient of friction will increase with the rise of aluminum content, and the plastic deformation of the alloy is strengthened, while the elastic deformation decreases.(5) The frictional force increases with the wear depth since the accumulation phenomenon of atoms becomes more obvious.

  • 20.
    Liu, Min
    et al.
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Key Lab Marine Mat & Related Technol, Zhejiang Key Lab Marine Mat & Protect Technol, Ningbo 315201, Peoples R China..
    Jin, Ying
    Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Beijing 102206, Peoples R China..
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Relevance of implicit and explicit solvent in density-functional theory study of adsorption at electrochemical NaCl/Al interface2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, p. 103425-, article id 103425Article in journal (Refereed)
    Abstract [en]

    The adsorption behavior of NaCl on Al(111) surface was studied by density functional theory (DFT) using implicit or explicit solvation models. Charge and total energy of adsorption systems indicate that the inclusion of an implicit solvent is necessary to construct a situation relevant to corrosion. Only certain configurations containing explicit water molecules with a direct NaCl interaction with Al are relevant to corrosion scenarios, attributed to a more predominant interaction of H2O-Al over NaCl-Al. Implicit and explicit solvent models yield consistent results, confirming that both solvent models can be used to study Cl- adsorption on Al within a corrosion regime.

  • 21.
    Liu, Min
    et al.
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Zhejiang Key Lab Marine Mat & Protect Technol, Key Lab Marine Mat & Related Technol, Ningbo 315201, Peoples R China..
    Pu, Jibin
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Zhejiang Key Lab Marine Mat & Protect Technol, Key Lab Marine Mat & Related Technol, Ningbo 315201, Peoples R China..
    Huang, Shuo
    China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Peoples R China..
    Wang, Yongxin
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Zhejiang Key Lab Marine Mat & Protect Technol, Key Lab Marine Mat & Related Technol, Ningbo 315201, Peoples R China..
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Density-functional theory study of point defect formation and diffusion in alpha-alumina and effects of applied strain and alloy doping2023In: Materials Today Communications, ISSN 2352-4928, Vol. 34, article id 105068Article in journal (Refereed)
    Abstract [en]

    Oxidation of alumina-forming alloys and breakdown of a-Al2O3 are important processes for alloys used in hightemperature environments. By using density-functional theory simulations, we investigate the formation and diffusion of three common point defects. Influences of diffusion pathway, axial strain and alloy doping on defect energetics during its formation and diffusion are systematically investigated. Results indicate a positive correlation between the diffusion energy barrier and the pathway length. We highlighted that diffusion barrier of vacancy defects can be reduced to that of interstitial defects by applying tensile strain, indicating that the strain state can transform the diffusion mechanism within a-Al2O3 . Moreover, the alloying dopants (Cr, Mo, Cu, Si, Y, Zr) investigated here can be categorized as: inhibitive, promotive, and inert, depending on their roles in determining the diffusion barrier of oxygen vacancy, which is analyzed by the element-dependent substitution energies, atomic radius, electronegativity, volumetric change, and electronic transition.

  • 22.
    Liu, Zeliang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Yanshan Univ, Key Lab Mech Reliabil Heavy Equipments & Large Str, Qinhuangdao 066004, Peoples R China.
    Li, Huijian
    Yanshan Univ, Key Lab Mech Reliabil Heavy Equipments & Large Str, Qinhuangdao 066004, Peoples R China..
    Yang, Xiao
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Quadruple perovskite CaCu3Fe2Re2O12: A potential actuator based on a multiscale model2022In: Materials Today Communications, ISSN 2352-4928, Vol. 33, article id 104811Article in journal (Refereed)
    Abstract [en]

    In this study, the magnetic structure of CaCu3Fe2Re2O12 is analyzed combined on a macro to micro-scale. To combine first-principles calculations and finite element methods, the magnetic properties, Young's modulus and Poisson's ratio are used as input parameters in the finite element methods calculations. As a function of applied magnetic field and actuator structure, the energy loss and magnetostrictive coefficient of an magnetostrictive actuator are identified. When the voltage and frequency are specified, a small bar radius and narrow air gap are preferred for a high magnetostrictive coefficient. The total range of simulation parameters results in a large magnetostrictive coefficient of 2700 ppm, which is higher than the one for Tb-Dy-Fe alloys. According to our results, CaCu3Fe2Re2O12 can be designed to be used as actuators by controlling the structures and applying magnetic fields.

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  • 23.
    Lousada, Claudio M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Graphene, phosphorene and silicene coatings on the (0001) surfaces of hcp metals: Structural stability and hydrophobicity2022In: Materials Today Communications, ISSN 2352-4928, Vol. 33, p. 104281-104281, article id 104281Article in journal (Refereed)
    Abstract [en]

    Single atomic layer or monolayer (ML) 2D materials have unique features that can be relevant for protection and functionalization of high-performance surfaces. Here we report a combined density functional theory and ab initio molecular dynamics study on the stability of graphene (Gr), phosphorene (Pp) and silicene (Sl) coatings at the most stable (0001) surface of the metals that have hcp structure at room temperature: Hf, Mg, Os, Re, Ru, Sc, Ti, Zn and Zr. We found that the three 2D materials are stable at the surfaces of many of these metals: Gr is stable at Os, Re, Ti, Zn and Zr; Pp is stable in the blue form at Hf, Mg, Ti and Zr; Sl is stable in the 2D zigzag structure at Hf, Mg and Ti and in the planar form at the Zr surface. For the remaining metals Gr, Pp and Sl do not form van der Waals bonded MLs. In those cases we found structures such as 2D arrangements of mixed hexagons and pentagons, trigonal pyramidal structures and 2 half-monolayers. Many of these structures are very stable coatings covalently bound to the surfaces with considerable adsorption energies that can reach − 2 eV per atom of the coating. Gr imparts hydrophobicity to the surfaces of all materials here studied and increases the distance between these and the first H2O layer by as much as 75 % for Gr coated Ti. These H2O layers have increased rigidity despite being located further apart from the surfaces. These effects could be explored for the protection or functionalization of high-performance systems such as metallic electrodes for example.

  • 24.
    Lupi, Giorgia
    et al.
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    de Menezes, João Teixeira Oliveira
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Belelli, Filippo
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Bruzzo, Francesco
    Fraunhofer, Institut für Werkstoff und Strahltechnik, Winterbergstraße 28, 01277 Dresden, Germany.
    López, Elena
    Fraunhofer, Institut für Werkstoff und Strahltechnik, Winterbergstraße 28, 01277 Dresden, Germany.
    Volpp, Joerg
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Castrodeza, Enrique Mariano
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Casati, Riccardo
    Department of Mechanical Engineering, Politecnico di Milano, Via G. La Masa 34, 20156 Milano (MI), Italy.
    Fracture toughness of AlSi10Mg alloy produced by direct energy deposition with different crack plane orientations2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107460Article in journal (Refereed)
    Abstract [en]

    Three-point bending fracture toughness and tensile specimens were tested at room temperature along different crack plane orientations and loading directions. Before being machined and tested, the printed samples were subjected to heat treatment at 300 °C for 2 h to relieve the residual stresses. Microstructural and fractographic analyses were performed to investigate the fracture mechanisms and the crack propagation paths for each crack orientation. Significant differences in the fracture toughness were observed among the crack plane orientations. Specimens with cracks oriented in the X-Y direction featured the highest fracture toughness values (JIc = 11.96 kJ/m2), whereas the Z-Y crack orientation (perpendicular to the printing direction) performed the lowest fracture toughness values (JIc = 8.91 kJ/m2). The anisotropy in fracture toughness is mainly related to a preferential crack propagation path along the melt pool boundaries. At melt pool boundaries, pores are preferentially placed, coarsening of the microstructure occurs and there is higher Si content, leading to that area being less ductile and less resistant to crack propagation.

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  • 25.
    Mi, Tran Yen
    et al.
    Can Tho Univ, Coll Nat Sci, 3-2 Rd, Can Tho City 94115, Vietnam.
    Khanh, Nguyen Duy
    Thu Dau Mot Univ, Inst Appl Technol, Thu Dau Mot City, Binh Duong Prov, Vietnam.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Tien, Nguyen Thanh
    Can Tho Univ, Coll Nat Sci, 3-2 Rd, Can Tho City 94115, Vietnam.
    Diverse structural and electronic properties of pentagonal SiC2 nanoribbons: A first-principles study2021In: Materials Today Communications, ISSN 2352-4928, Vol. 26, article id 102047Article in journal (Refereed)
    Abstract [en]

    Through the first-principles calculations, a generalized theoretical framework is used to systematically investigate the structural and electronic properties of the buckled SiC2 pentagon-based nanoribbons (p-SiC2 nanoribbons), including the formation energies, optimal structural parameters, phonon spectrum, electronic band structures, orbital-projected density of states (DOSs) and partially charge density distributions. The dimensional reduction of the pentagonal SiC2 nanosheet result in the four distinct edge structures of the p-SiC2 nanoribbons, including ZZ-ribbon, ZA-ribbon, AA-ribbon and SS-ribbon, in which the p-SiC2 SS-ribbon achieves the greatest thermal and dynamic stability among the other ones. Energy gaps of the p-SiC2 nanoribbons are created mainly owing to the competition in the edge structures, finite-size confinements and asymmetry of chemical bonds in the tetrahedral lattice. The critical width is found at W = 14, where the band gaps are dramatically reduced as the widths increase below the critical one, while the band gaps are hardly sensitive with the enlarged widths beyond the critical one. The unusual properties of the p-SiC2 nanoribbons is very potential for applications in optoelectronic devices, especially in photovoltaics.

  • 26.
    Neitzel, Nicolas
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Eder, Michaela
    Max Planck Institute of Colloids and Interfaces, Germany.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Michigan Technological University, USA.
    Walther, Thomas
    IKEA Industry AB, Sweden.
    Adamopoulos, Stergios
    Swedish University of Agricultural Sciences, Sweden.
    Chemical composition, particle geometry, and micro-mechanical strength of barley husks, oat husks, and wheat bran as alternative raw materials for particleboards2023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106602Article in journal (Refereed)
    Abstract [en]

    Particleboards are used worldwide in various industry segments, like construction and furniture production. Nevertheless, increase in wood prices and logistical challenges urge the particleboard industry to find alternative raw materials. By-products and residues from the agricultural and food industries could offer possibilities for material sourcing at a local level. This study aimed to investigate the chemical composition, particle geometry, anatomical structure, and microtensile characteristics of such material, specifically barley husks (BH), oat husks (OH), and wheat bran (WB). Barley and oat husks were found to have comparable hemicelluloses and lignin contents to industrial wood chips but contained more ash. Wheat bran was rich in extractives and showed high buffering capacity. Light microscopy and microcomputed tomography revealed details of leaf structure for BH and OH as well as the multi-layer structure of WB. The ultimate microtensile strength of BH, various OH samples, and WB were respectively 2.77 GPa, 0.84-2.42 GPa, and 1.45 GPa. The results indicated that the studied materials could have potential uses as furnish materials in non-load bearing particleboards, where thermal or acoustic insulation properties are desirable.

  • 27.
    Nilsson Åhman, Hanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Swerim AB.
    Larsson, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Wahman, Clarence
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Mellin, Pelle
    Swerim AB.
    D'Elia, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Higher Laser power improves strength but reduces corrosion resistance of Mg WE43 processed by powder bed fusion2024In: Materials Today Communications, ISSN 2352-4928, Vol. 39, article id 108979Article in journal (Refereed)
    Abstract [en]

    Powder bed fusion – laser beam (PBF-LB) of Mg alloys provides new possibilities for the production of complex structures with optimized designs, both for weight reduction in aerospace applications, as well as for patient-specific implants in orthopedic applications. However, even though numerous studies have been carried out on the topic, the influence of the individual PBF-LB process parameters on the microstructure and resulting material properties of Mg alloys remains ambiguous. Thus, this study aims to investigate the influence of laser power on the surface roughness, microstructure and resulting key material properties, namely corrosion resistance and mechanical performance. Samples were produced by PBF-LB from gas atomized Mg-4%Y-3%Nd-0.5%Zr (WE43) alloy powder, using three different laser powers: 60 W, 80 W, and 90 W. Contrary to expectation, the 90 W samples exhibited the highest degradation rate, while 60 W samples had the lowest, despite the latter having highest surface roughness and large internal pores. The higher degradation rate for the 90 W samples was instead found to stem from the near-surface microstructure. The higher energy input and subsequently reduced grain size, resulted in an increased amount of second phase precipitates than for the 60 W samples, thereby increasing the tendency for pitting via microgalvanic corrosion. For the tensile strength and elongation at break, the opposite trend was observed. Here, a reduction in grain size and an increase in precipitates for the 90 W samples were found to be beneficial. In conclusion, a definite influence of laser power on the formation of microstructure was observed, ultimately impacting the resulting corrosion and tensile properties of WE43. Future work should investigate the influence of other PBF-LB process parameters, with the aim of establishing an optimum balance between corrosion resistance and mechanical properties.

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  • 28.
    Niu, Caoping
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China.;Univ Sci & Technol China, Hefei 230026, Peoples R China..
    Zhao, Jing
    Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China.;Univ Sci & Technol China, Hefei 230026, Peoples R China..
    Xia, Wenming
    Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China.;Univ Sci & Technol China, Hefei 230026, Peoples R China..
    Chen, Guo
    Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China.;Univ Sci & Technol China, Hefei 230026, Peoples R China..
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Zhang, Jie
    Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Wang, Xianlong
    Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, HFIPS, Hefei 230031, Peoples R China.;Univ Sci & Technol China, Hefei 230026, Peoples R China..
    Configuration stability and physical properties of new diamondene structure2023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106465Article in journal (Refereed)
    Abstract [en]

    The structure of monolayer diamond or diamondene based on bi-layer graphene through pressure conversion, combining characteristics of both graphene and diamond, has been confirmed theoretically and experimentally. In this work, by extending diamondene structure to the minimum repeating unit of bulk diamond along different crystallographic orientations, the configuration stability and physical properties of 21 kinds of diamondene were systematically investigated based on first-principles methods, and effects of hydrogen saturation were also presented. It was found that diamondene formed by compressing layered graphene would graphitize, and surface termination could prevent the graphitization. The electronic properties of diamondene can be adjusted by the concentration of H atoms with the bandgap varying from 0 eV to 3.45 eV, and some configurations exhibit ferromagnetism or anti-ferromagnetism. Moreover, diamondene has a high Young's modulus comparable to bulk diamond. Particularly, the configuration containing dumbbell units is twice as hard as diamond. The formation energies of all stable diamondene configurations were illustrated, and it was found that it is easier to synthesize diamondene by compressing few-layer graphene. Furthermore, the instability law of two-dimensional carbon structure was systematically discussed, which is important for designing new carbon allotropes.

  • 29.
    Onate, Angelo
    et al.
    Univ Concepcion, Fac Engn, Dept Mat Engn DIMAT, Edmundo Larenas 270, Concepcion, Chile..
    Alvarado Ávila, María Isabel
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Medina, Carlos
    Univ Concepcion, Fac Engn, Dept Mech Engn DIM, Edmundo Larenas 219, Concepcion, Chile..
    Villegas, Claudio
    Univ Bio Bio, Fac Engn, Dept Mech Engn DIMEC, Ave Collao 1202, Concepcion, Chile.;Rhein Westfal TH Aachen, Inst Mech Theory Machine Dynam & Robot IGMR, Eilfschornsteinstr 18, D-52062 Aachen, Germany..
    Ramirez, Jesus
    Univ Concepcion, Fac Engn, Dept Mat Engn DIMAT, Edmundo Larenas 270, Concepcion, Chile..
    Sanhueza, Juan Pablo
    Univ Concepcion, Fac Engn, Dept Mat Engn DIMAT, Edmundo Larenas 270, Concepcion, Chile..
    Melendrez, Manuel
    Univ Concepcion, Fac Engn, Dept Mat Engn DIMAT, Edmundo Larenas 270, Concepcion, Chile..
    Rojas, David
    Univ Concepcion, Fac Engn, Dept Mat Engn DIMAT, Edmundo Larenas 270, Concepcion, Chile..
    Characterization of Nb-Si-doped low-carbon steel treated by quenching and partitioning: Thermic treatment in two stages supported by computational thermodynamical simulation and controlled sample dimensions2023In: Materials Today Communications, ISSN 2352-4928, Vol. 34, article id 105335Article in journal (Refereed)
    Abstract [en]

    Quench and partition steels find wide use in the automotive industry because of their high capability of energy absorption. Industrial demands have prompted the expansion of this research field because of the influence these materials have on components that can absorb high energy of impact to reduce passenger damage, for example. The partition process's difficulties lie mainly in controlling the thermodynamics and the kinetics of the phase transformation. Both affect achieving adequate austenite retention and optimal mechanical properties. Many researchers have attempted to increase these materials' energy absorption efficiency by incorporating micro -alloying elements that control phase transformation during the partitioning process, typically done in three steps. However, no research has been carried out on this topic using Nb and Si microalloying on low-carbon steels in two stages. Therefore, an alloy was designed and modelled with mechanical reinforcement by precipitation and transformation-induced plasticity (TRIP), doping the steel with Nb and Si in a two-stage quenching and parti-tioning process. Then, steel samples were fabricated to validate the model. There were two groups of samples with different dimensions to evaluate the sensitivity of austenite retention concerning the sample thickness. The main results showed that 10.75% of retained austenite allows an energy absorption of 30.55 GPa% with a two -stage quenching and partitioning heat treatment. Sample thickness influences austenite retention due to diffusion kinetics during the partitioning process. Finally, virtual tests quantified the unit strain energy absorption of the retained austenite at 1.9 mJ at 25 degrees C.

  • 30.
    Pandey, Vidit
    et al.
    Aligarh Muslim Univ, Dept Phys, Aligarh 202002, India.
    Adiba, Adiba
    Aligarh Muslim Univ, Dept Phys, Aligarh 202002, India.
    Nehla, Priyanka
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Munjal, Sandeep
    Natl Forens Sci Univ, Ponda 403401, Goa, India.;Univ Delhi, Dept Phys & Astrophys, New Delhi 110007, India.
    Ahmad, Tufail
    Aligarh Muslim Univ, Dept Phys, Aligarh 202002, India.
    Bipolar resistive switching with multiple intermediate resistance states in Mn3O4 thin film2023In: Materials Today Communications, ISSN 2352-4928, Vol. 34, article id 105484Article in journal (Refereed)
    Abstract [en]

    The research on resistive switching phenomenon-based memory devices has become an important topic in computing and data storage technology. In this study, bipolar resistive switching based Al/Mn3O4/FTO RRAM device with multi-level resistance states has been investigated. The current-voltage and resistance-temperature analyses were performed to explore the behavior and conduction mechanisms of the fabricated RRAM device. A gradual RESET was obtained during the switching from a high resistance state to a low resistance state with three intermediate resistance states at different stop voltages. The program/erase and data retention tests were performed to investigate the stability, uniform switching, and non-volatile behavior of the fabricated device. A schematic representation of the formation of conducting filamentary path between the top and bottom electrodes has also been illustrated. The fabricated RRAM device has the potential to fulfill the requirements for application in high-density non-volatile memory devices.

  • 31.
    Revathy Rajan, Prasath Babu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ma, Taoran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Odqvist, Joakim
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    A transmission electron microscopy study of discontinuous precipitation in the high misfit system (Ti,Zr)C2020In: Materials Today Communications, ISSN 2352-4928, Vol. 25, article id 101281Article in journal (Refereed)
    Abstract [en]

    (Ti,Zr)C synthesized and aged in the immiscibility temperature range was investigated to improve understanding of the mechanism of phase separation, particularly the nucleation and early growth stages. The phase separation was observed to occur through discontinuous precipitation at grain boundaries. The nuclei were found enriched in titanium and associated with dislocations intersecting grain boundaries. During growth, zirconium enriched regions form subsequently and the semi-coherent interfaces of the Ti- and Zr-rich phases contain misfit dislocations. These observations suggest that dislocations play an important role for the nucleation and growth during discontinuous precipitation in the (Ti,Zr)C high misfit miscibility gap system.

  • 32.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Creep at low stresses in aluminium (Harper-Dorn) and in an austenitic stainless steel with a stress exponent of 12023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106558Article in journal (Refereed)
    Abstract [en]

    Creep tests at very low stresses are often terminated before the stationary stage is reached, which makes it essential to use a model for primary creep to assess the results. Such a model was developed in a recent paper by the author. The model is applied to creep at very low stresses where dislocation creep is the controlling mechanism. Two cases are investigated. i) Aluminium at very high temperatures. This is usually referred to as Harper-Dorn creep. ii) The austenitic stainless steel 316H at 700oC. Most aluminium data for the considered case can be modelled assuming stationary conditions, but some data has to be represented with the primary creep model giving stress exponents down to 1. Contrary to the case for aluminium, the data for 316H at low stresses are very far from stationary conditions. The model results give in agreement with observations a stress exponent of 1 and stress strain curves consistent with the & phi; (phi) model, i.e. an exponentially decreasing strain rate with increasing time. The consistency with the & phi; model verifies that dislocation creep is the controlling mechanism in spite of the fact that the Coble model gives a higher strain rate for diffusion creep.

  • 33.
    Schulz, Fiona
    et al.
    Chalmers Univ Technol, Sweden; Univ Bundeswehr Munchen, Germany.
    Lindgren, Kristina
    Chalmers Univ Technol, Sweden.
    Xu, Jinghao
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Hryha, Eduard
    Chalmers Univ Technol, Sweden.
    Gamma prime formation in nickel-based superalloy IN738LC manufactured by laser powder bed fusion2024In: Materials Today Communications, ISSN 2352-4928, Vol. 38, article id 107905Article in journal (Refereed)
    Abstract [en]

    Complex components for high-temperature gas turbine applications require materials that offer a combination of excellent high-temperature strength and oxidation resistance. Nickel-based superalloys with high gamma prime (gamma)' volume fractions are particularly suited for these applications, especially combined with additive manufacturing for intricate geometries. Despite the complex thermal history that these materials experience during laser powder bed fusion (LPBF) processing, gamma'formation is suppressed when manufacturing IN738LC, which has a medium equilibrium gamma'content of about 40-50 vol%. This study follows gamma'formation in LPBF IN738LC during subsequent annealing treatments at temperatures ranging from 745 C-degrees to 865 C-degrees, creating an experimentally determined TTT (temperature-time-transformation) diagram. This diagram is largely based on scanning electron microscopy (SEM) imaging supported by Vickers hardness measurements and scanning transmission electron microscopy (STEM) bright field imaging. Atom probe tomography (APT) of the as-built material indicated nm-sized regions depleted in Cr and enriched in Ni, Al, and Ti, but show no characteristic superlattice patterns in TEM diffraction. APT and TEM diffraction analysis of material annealed at 850 C for 3 min confirmed the presence of the gamma'phase but indicated that gamma'had formed through spinodal decomposition instead of precipitation.

  • 34.
    Shanmugam, Vigneshwaran
    et al.
    Saveetha Inst Med & Tech Sci, Saveetha Sch Engn, Dept Mech Engn, Chennai 602105, Tamil Nadu, India..
    Sreenivasan, S. N.
    Adishankara Inst Engn & Technol, Dept Mech Engn, Kalady 683574, Kerala, India..
    Mensah, Rhoda Afriyie
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    Forsth, Michael
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    Sas, Gabriel
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Neisiany, Rasoul Esmaeely
    Hakim Sabzevari Univ, Fac Engn, Dept Mat & Polymer Engn, Sabzevar 9617976487, Iran..
    Tu, Yongming
    Norwegian Univ Sci & Technol NTNU, Dept Mech & Ind Engn, SP Andersens Veg 3, N-7031 Trondheim, Norway.;Southeast Univ, Sch Civil Engn, Nanjing 211189, Peoples R China..
    Das, Oisik
    Luleå Univ Technol, Dept Civil Environm & Nat Resources Engn, Struct & Fire Engn Div, S-97187 Luleå, Sweden..
    A review on combustion and mechanical behaviour of pyrolysis biochar2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, p. 103629-, article id 103629Article, review/survey (Refereed)
    Abstract [en]

    Biochar has unique physical and chemical properties, making it a viable and sustainable future generation material for a variety of applications. The applications include power generation, composite production, construction (as a reinforcement), and soil amendment. The inherent good mechanical and combustion (or fire) resistance properties of biochar are attractive, however, there are limited reports, despite its effects on bulk material properties being well-documented. Comprehending these innate properties of biochar is critical for tailoring the mechanical and fire properties of biochar-based materials and structures. Therefore, an attempt has been made in this article to garner and analyse literatures reported on the mechanical and combustion properties of biochar without being integrated with a material or structural system (e.g. composite). Biochar produced at high pyrolysis temperatures (>500 celcius) showed high fire resistance property, because of the absence of the volatile matters and development of strong C-C covalent bonds. The mechanical and combustion properties of biochar can be controlled by varying the biochar size, porous nature, and pyrolysis temperature. The information presented in this article is crucial and can be used as a guide to develop biochar-based materials and structures for mechanical and fire resistance applications.

  • 35.
    Shanmugam, Vigneshwaran
    et al.
    Department of Mechanical Engineering, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602 105, Tamilnadu, India.
    Sreenivasan, S.N.
    Department of Mechanical Engineering, Adishankara Institute of Engineering and Technology, Kalady Kerala – 683574, India.
    Mensah, Rhoda Afriyie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Försth, Michael
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hedenqvist, Mikael S
    Department of Fibre and Polymer Technology, Polymeric Materials Division, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm 100 44, Sweden.
    Neisiany, Rasoul Esmaeely
    Department of Materials and Polymer Engineering, Faculty of Engineering, Hakim Sabzevari University, Sabzevar, 9617976487, Iran.
    Tu, Yongming
    Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology NTNU, S.P. Andersens Veg 3, Trondheim, 7031, Norway; School of Civil Engineering, Southeast University, Nanjing 211189, China.
    Das, Oisik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    A Review on Combustion and Mechanical Behaviour of Pyrolysis Biochar2022In: Materials Today Communications, ISSN 2352-4928, Vol. 31, article id 103629Article, review/survey (Refereed)
    Abstract [en]

    Biochar has unique physical and chemical properties, making it a viable and sustainable future generation material for a variety of applications. The applications include power generation, composite production, construction (as a reinforcement), and soil amendment. The inherent good mechanical and combustion (or fire) resistance properties of biochar are attractive, however, there are limited reports, despite its effects on bulk material properties being well-documented. Comprehending these innate properties of biochar is critical for tailoring the mechanical and fire properties of biochar-based materials and structures. Therefore, an attempt has been made in this article to garner and analyse literatures reported on the mechanical and combustion properties of biochar without being integrated with a material or structural system (e.g. composite). Biochar produced at high pyrolysis temperatures (>500 ℃) showed high fire resistance property, because of the absence of the volatile matters and development of strong C-C covalent bonds. The mechanical and combustion properties of biocharcan be controlled by varying the biochar size, porus nature, and pyrolysis temperature. The information presented in this article is crucial and can be used as a guide to develop biochar-based materials and structures for mechanical and fire resistance applications.

  • 36.
    Sorrentino, Andrea
    et al.
    Natl Res Council Italy, IPCB, I-23900 Lecce, Italy..
    Gorrasi, Giuliana
    Univ Salerno, Dipartimento Ingn Ind, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy..
    Bugatti, Valeria
    Univ Salerno, Dipartimento Ingn Ind, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy..
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Univ Salerno, Dipartimento Chim & Biol A Zambelli, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy.;KTH Royal Inst Technol, Dept Fibre & Polymer Technol, S-11428 Stockholm, Sweden..
    Pappalardo, Daniela
    Univ Sannio, Dipartimento Sci & Tecnol, Via Mulini, I-82100 Benevento, Italy..
    Polyethylene-like macrolactone-based polyesters: Rheological, thermal and barrier properties2018In: Materials Today Communications, ISSN 2352-4928, Vol. 17, p. 380-390Article in journal (Refereed)
    Abstract [en]

    Linear aliphatic poly(ester)s are receiving increasing interest due to their properties comparable to that of common polyethylene. In this work, unsaturated macrolactone omega-6-hexadecenlactone (6HDL) is used for the preparation of long-methylene chain aliphatic polyesters by metal-catalyzed ring-opening polymerization (ROP). Block and random copolymer of e-caprolactone (CL) are then synthetized. The microstructures of these polyesters are characterized by H-1 and C-13 NMR. Their rheological, thermal and barrier properties are evaluated and discussed. For comparison purposes, the properties of the relative homopolymers are also determined. Results show that the properties of these polymers differ depending on the main chain structure. In particular, the viscoelastic behavior of the copolymer sample shows an order-disorder transition in the temperature range of 75-85 degrees C. Thermogravimetric analysis and barrier properties show that the copolymers have a resistance to the diffusion of gases and vapors intermediate between that of the parent homopolymers.

  • 37.
    Spartacus, Gabriel
    et al.
    Univ Paris Saclay, Serv Rech Met Appl, CEA, F-91191 Gif Sur Yvette, France.;Brinellvagen 23, S-11428 Stockholm, Sweden..
    Malaplate, Joel
    Univ Paris Saclay, Serv Rech Met Appl, CEA, F-91191 Gif Sur Yvette, France..
    De Geuser, Frederic
    Univ Grenoble Alpes, CNRS, Grenoble INP, SIMAP, F-38000 Grenoble, France..
    Sornin, Denis
    Univ Paris Saclay, Serv Rech Met Appl, CEA, F-91191 Gif Sur Yvette, France..
    Mouton, Isabelle
    Univ Paris Saclay, Serv Rech Met Appl, CEA, F-91191 Gif Sur Yvette, France..
    Guillou, Raphaelle
    Univ Paris Saclay, Serv Rech Met Appl, CEA, F-91191 Gif Sur Yvette, France..
    Deschamps, Alexis
    Univ Grenoble Alpes, CNRS, Grenoble INP, SIMAP, F-38000 Grenoble, France..
    The impact of outgassing on the nano-oxides kinetics of ferritic oxide dispersion strengthened steel2022In: Materials Today Communications, ISSN 2352-4928, Vol. 33, article id 104929Article in journal (Refereed)
    Abstract [en]

    Oxide Dispersion Strengthened (ODS) steels are studied for their application in fission and fusion nuclear power plants. These steels are processed by powder metallurgy involving a high energy milling of Fe-Cr with oxides powders, followed by outgassing and hot consolidation. The temperature increase during these last two stages triggers the precipitation of a fine dispersion of nano-oxides. The outgassing stage is generally conducted at temperature between 300 and 800 degrees C for several hours, which can already trigger the formation of nano-oxides, and thus may have an influence on the final nano-oxide characteristics. In this work we assess the nano-oxides size by Small Angle X-Ray Scattering (SAXS) and get insight on the nano-oxides chemical and structural prop-erties by comparison between SAXS and Atom Probe Tomography (APT) during a thermal treatment at 700 degrees C for 5 h, simulating the outgassing stage. We show that despite that the nano-oxides slightly grow during the 700 degrees C heating, the final properties of the nano-oxides in term of size and number density are extremely close to those where no 700 degrees C isothermal was applied. Moreover, the growth rate of the nano-oxides is surprisingly higher at 700 degrees C than 1100 degrees C. APT and SAXS comparison shows that the nano-oxides do not stabilize in terms of stoi-chiometry and structure in the studied conditions, and that a small quantity of Al remain in the precipitates during this 700 degrees C isothermal treatment. Both of these factors could influence the nano-oxides kinetics at low temperature.

  • 38.
    Sun, Xiaoyu
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Cent South Univ, Peoples R China.
    Zhang, Longfei
    Cent South Univ, Peoples R China.
    Pan, Yanming
    Cent South Univ, Peoples R China.
    Zhu, Lilong
    Yantai Univ, Peoples R China.
    Huang, Zaiwang
    Cent South Univ, Peoples R China.
    Jiang, Liang
    Yantai Univ, Peoples R China.
    Tuning Mo/W ratio to improve high temperature oxidation resistance of single crystal nickel base superalloys2024In: Materials Today Communications, ISSN 2352-4928, Vol. 38, article id 107826Article in journal (Refereed)
    Abstract [en]

    The effect of different Mo/W ratios of three single crystal nickel base superalloys on the oxidation behavior was investigated at 1100 degrees C. Both isothermal and cyclic oxidation tests showed that increasing Mo/W ratio corresponds to lower weight change and improved resistance. The microscopic observation uncovers that the harmful effect of Mo is limited by the dense Al2O3 scale. In contrast, excessive W leads to fast growth of interlayer and its premature spallation. This research proposes and verifies a new way to improve oxidation resistance of alloy, namely, balancing the harmful effect of refractory elements.

  • 39. Wei, Shuhe
    et al.
    Xiao, Yan
    Jiang, Hanwen
    Héraly, Frédéric
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Liangshun
    Huang, Wanyi
    Yuan, Jiayin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lang, Meidong
    Polypeptide-based vapor-responsive porous poly(ionic liquid) actuators: From reversible to unexpectedly irreversible actuation2023In: Materials Today Communications, ISSN 2352-4928, Vol. 35, article id 105878Article in journal (Refereed)
    Abstract [en]

    Soft actuators capable of large and swift locomotion in combination with biocompatibility hold great potential in medicine and healthcare applications. In this contribution, a polypeptide-type poly(ionic liquid) (termed “PLL-PMIM-Tf2N”) was designed and synthesized by post-polymerization modification of poly-L-lysine; Next, via controlled electrostatic complexation with poly(acrylic acid) (PAA) or poly(L-glutamic acid) (PLG), porous membrane actuators termed PLL-PMIM-Tf2N/PAA or PLL-PMIM-Tf2N/PLG, respectively, were tailor-made. Hemolytic tests support excellent blood cell compatibility of the fully polypeptide-based PLL-PMIM-Tf2N/PLG actuator. The as-made soft actuators could bend significantly up to 500°with a maximum curvature of 7 cm−1 in response to solvent vapor in a fast actuation process within 2 s. Their high sensitivity towards solvent molecules equips them with skills to distinguish solvent isomers, as exemplified by butanol isomers, in terms of bending curvature due to varied molecular interactions between the actuator and the isomer. To be highlighted is an unusual irreversible actuated tubular state of the fully polypeptide-based PLL-PMIM-Tf2N/PLG actuator that is stable in shape and resembles bionic blood vessels. Such polypeptide-type poly(ionic liquid) actuators are of significant value in future development of biocompatible devices for medical and healthcare applications.

  • 40.
    Xie, Shijie
    et al.
    Southeast Univ, Sch Civil Engn, Nanjing 210096, Jiangsu, Peoples R China..
    Lin, Hang
    Cent South Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China..
    Chen, Yifan
    Cent South Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China..
    Duan, Hongyu
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Liu, Hongwei
    Cent South Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China..
    Liu, Baohua
    Cent South Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China..
    Prediction of shear strength of rock fractures using support vector regression and grid search optimization2023In: Materials Today Communications, ISSN 2352-4928, Vol. 36, article id 106780Article in journal (Refereed)
    Abstract [en]

    The shear strength of rock fractures serves as a crucial control on the strength and deformation behavior of engineering rock masses. To reduce the uncertainties in the shear strength evaluation, a hybrid machine learning model (GS-SVR model) of the support vector regression (SVR) underpinned by the grid search optimization algorithm (GS) was proposed. It achieves the prediction of shear strength by generalization and deduction of a large amount of data on rock fracture parameters, which avoids the complex derivation of theoretical equations. For practical application, a dataset comprising more than 134 shear tests on various rocks was compiled to collect the relevant three-dimensional morphological and mechanical parameters for training and prediction. Three classical shear strength models and the original SVR model were introduced for further comparison. Finally, sensitivity analysis was carried out to explore the relative importance of input variables to the shear strength. The results showed that the GS-SVR model (correlation coefficient R2 = 0.984, root mean squared error RMSE=0.383) outperformed the original SVR model (R2 = 0.936, RMSE=0.568). Moreover, compared with three classical shear strength models, the prediction results of the GS-SVR model were also most consistent with the experimental results (with the lowest RMSE and the highest R2). This machine learning model enhanced by GS can be used as a reliable and accurate shear strength prediction tool to partially replace laboratory tests to save costs.

  • 41.
    Xing, Qiuwei
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Feltrin, Ana Carolina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Processing, microstructure and high temperature dry sliding wear of a Cr-Fe-Hf-Mn-Ti-Ta-V high-entropy alloy based composite2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102657Article in journal (Refereed)
    Abstract [en]

    High-entropy materials are promising for high-temperature applications. In order to achieve high-temperature wear resistance, a novel high-entropy alloy based composite, (CrMnFeHf)7.14(TiTaV)23.81, was designed and consolidated by spark plasma sintering at 1320 ℃ following thermodynamic simulations using the CALPHAD method. The microstructure of the sintered composite revealed a Ti30V36Ta19Cr5Mn5Fe4Hf1 body-centered cubic (bcc) high-entropy alloy matrix with C14 Laves phase and carbide particles. The Laves phase and carbide particles of higher hardness were formed in situ during the sintering in a bcc matrix. The dry sliding wear behavior of the composite against Si3N4 ceramic counter ball (10 N, 30 min) from room temperature to 600 ℃ was investigated. The high-entropy alloy composite showed a superior resistance to wear against Si3N4 ceramic due to the presence of reinforcing C14 laves phase and carbide particles in the high-entropy alloy matrix. Furthermore, the wear rate reduced with increasing temperature. The dominating wear mechanisms of the high-entropy alloy composite were adhesive wear and abrasive wear at room temperature and 200 ℃, oxidation wear and abrasive wear at 400 ℃ and oxidation wear and delamination wear at 600 ℃. The formation of multiple oxides, presence of Laves and carbide phase contributed to the low volume loss of high-entropy alloy composite during wear tests at high temperatures.

  • 42.
    Zendejas Medina, León
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    de Costa, Marcus Vinicius Tavares
    Karlstad Univ, Dept Engn & Chem Sci, SE-65188 Karlstad, Sweden..
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetron sputtered high entropy alloy/amorphous carbon nanocomposite coatings2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107389Article in journal (Refereed)
    Abstract [en]

    Magnetron sputter deposition of metal/carbon nanocomposites has been explored for many metals and a few alloys. In this paper, the formation of nanocomposites based on complex high entropy alloys (HEAs) was explored, focusing on the effect of the average carbon affinity on the phase formation. Two HEA systems were compared: CoCrFeMnNi and Cr26Fe27Ni27Ta20. For each alloy, around 20-50 at% carbon was added through combinatorial co-sputtering. Thermodynamic calculations predicted decomposition of these materials into multiple alloy phases, metal carbides, and, at higher concentrations, free graphitic carbon. Free carbon was found in the coatings at carbon concentrations above 28 and 33 at% for the CoCrFeMnNi and Cr26Fe27Ni27Ta20 systems, respectively, which agreed with the theoretical predictions. However, the segregation of metallic ele-ments and the formation of crystalline carbides were suppressed by the rapid quenching during deposition. All coatings were, instead, amorphous and consisted of either a single metallic phase or a mixture of a metallic phase and sp2- and sp3-hybridized carbon. Mechanical and electrochemical tests were performed, including in-situ fragmentation tests to quantify the crack resistance. The presence of free carbon made the coatings softer than the corresponding single-phase materials. Under tensile strain, the nanocomposite coatings formed a larger number of narrower cracks and exhibited less delamination at high strains.

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  • 43.
    Zendejas Medina, León
    et al.
    Uppsala University, Sweden.
    Tavares da Costa, Marcus Vinicius
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Donzel-Gargand, Olivier
    Uppsala University, Sweden.
    Nyholm, Leif
    Uppsala University, Sweden.
    Gamstedt, E. Kristofer
    Uppsala University, Sweden.
    Jansson, Ulf
    Uppsala University, Sweden.
    Magnetron sputtered high entropy alloy/amorphous carbon nanocomposite coatings2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107389Article in journal (Refereed)
    Abstract [en]

    Magnetron sputter deposition of metal/carbon nanocomposites has been explored for many metals and a few alloys. In this paper, the formation of nanocomposites based on complex high entropy alloys (HEAs) was explored, focusing on the effect of the average carbon affinity on the phase formation. Two HEA systems were compared: CoCrFeMnNi and Cr26Fe27Ni27Ta20. For each alloy, around 20–50 at% carbon was added through combinatorial co-sputtering. Thermodynamic calculations predicted decomposition of these materials into multiple alloy phases, metal carbides, and, at higher concentrations, free graphitic carbon. Free carbon was found in the coatings at carbon concentrations above 28 and 33 at% for the CoCrFeMnNi and Cr26Fe27Ni27Ta20 systems, respectively, which agreed with the theoretical predictions. However, the segregation of metallic elements and the formation of crystalline carbides were suppressed by the rapid quenching during deposition. All coatings were, instead, amorphous and consisted of either a single metallic phase or a mixture of a metallic phase and sp2- and sp3-hybridized carbon. Mechanical and electrochemical tests were performed, including in-situ fragmentation tests to quantify the crack resistance. The presence of free carbon made the coatings softer than the corresponding single-phase materials. Under tensile strain, the nanocomposite coatings formed a larger number of narrower cracks and exhibited less delamination at high strains. 

    Download full text (pdf)
    fulltext
  • 44.
    Zhang, Chenghang
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China b Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing 400044, PR China.
    Huang, Guangjie
    International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China b Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing 400044, PR China.
    Cao, Yu
    International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China b Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing 400044, PR China.
    Li, Qilei
    International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China b Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing 400044, PR China.
    Niu, Liqiang
    International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China b Shenyang National Laboratory for Materials Science, Chongqing University, Chongqing 400044, PR China.
    Liu, Qing
    College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, PR China.
    Characterizations of microstructure, crystallographic texture and mechanical properties of dissimilar friction stir welding joints for AA2024 and AA7075 under different tool shoulder end profiles2020In: Materials Today Communications, ISSN 2352-4928, Vol. 25, p. 101435-, article id 101435Article in journal (Refereed)
    Abstract [en]

    In this investigation, the influence of tool shoulder end profiles (concentric circle shoulder-CCS and three-helix shoulder-THS) and rotational speed (ROSP, 800, 1100, 1400 rpm) on microstructure and mechanical performance of the dissimilar FSW AA2024/7075 joints was analyzed in detail. The results indicated that the width of thermos-mechanical affected zone and the average grain size of nugget zone (NZ) in the CCS joints are lower than those in the THS joints, and they all increase with increasing the ROSP. There is a difference on the shear texture types generated in the different positions of the NZ in the CCS and THS joints. Tensile properties of the joints fabricated by employing the CCS tool are excellent compared to the THS tool. The maximum welding efficiency about 90.8 % can be obtained in the CCS joint at 1000 rpm. The fracture mode of the CCS and THS joints is ductile and brittle failure, respectively.

  • 45.
    Zhang, Jing
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Properties.
    He, Junjing
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    First-principles modeling of solute effects on thermal properties of nickel alloys2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102551Article in journal (Refereed)
    Abstract [en]

    The effects of Cr and W on high-temperature properties of Ni-based alloys are derived from first-principles calculations combined with a quasi-harmonic Debye model. The modeling procedure integrates all contributions from electronic excitations, magnetic fluctuations and lattice vibrations. The predicted lattice parameter and thermal expansion coefficient agree well with available reference values. The temperature dependence of elastic moduli for Ni-Cr alloys is described satisfactorily. Debye temperature has been calculated to show a strong volume dependence but a weak temperature dependence. A close relationship between the concentration dependence of elastic moduli and the volume dependence of Debye temperature, and thus the vibrational free energy, has been established. Besides, the softening of elastic moduli with increasing temperature is shown to be a result of thermal expansion which mainly comes from lattice vibrations. Therefore, lattice vibrations affect both temperature and concentration dependencies of elastic properties at elevated temperatures. With the help of Labusch-Nabarro model, solid solution hardening caused by Cr and W solutes in Ni has been analyzed. Moreover, the presence of solute atoms increases elastic anisotropy. The effects of Cr or W additions on the thermodynamic properties are found to be small compared to the effect of temperature.

  • 46.
    Zhao, Jun
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
    Gao, Tong
    College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
    Li, Yingru
    School of Advanced Materials and Mechatronic Engineering, Hubei Minzu University, Enshi, 445000, China.
    He, Yongyong
    State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Two-dimensional (2D) graphene nanosheets as advanced lubricant additives: A critical review and prospect2021In: Materials Today Communications, ISSN 2352-4928, Vol. 29, article id 102755Article in journal (Refereed)
    Abstract [en]

    Graphene is a two-dimensional nanomaterial with a monolayer of atomic thickness. Due to its high specific surface area, weak interlayer interaction and good chemical stability, graphene has shown remarkable tribological properties as a lubricant additive. This review focuses on the research progress on graphene-based additives witnessed in recent years. Various synthesis methods of graphene nanomaterials have been displayed, and the review especially highlights the preparation processes of graphene using as a lubricant additive. The dispersion stability of graphene in lubricants is a key concern that has been presented. Besides physical and chemical modifications, a new dispersion method of structural regulation, which has obvious self-dispersed effect, is also discussed in detail. Furthermore, the lubrication mechanisms of graphene additives have been summarized, which will be highly beneficial to optimize the synthesis processes and to regulate the microstructures of graphene for achieving better lubrication. Finally, the challenges and outlook of the future studies on graphene additives are presented in the field of lubrication.

  • 47.
    Ziaalmolki, Sahar
    et al.
    Univ Tabriz, Fac Phys, Tabriz, Iran..
    Aslibeiki, Bagher
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Univ Tabriz, Fac Phys, Tabriz, Iran..
    Zarei, Mahmoud
    Univ Tabriz, Dept Appl Chem, Res Lab Environm Remediat, Tabriz, Iran..
    Torkamani, Reza
    Univ Tabriz, Fac Phys, Tabriz, Iran..
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Enhanced visible-light-driven photocatalysis via magnetic nanocomposites: A comparative study of g-C3N4, g-C3N4/Fe3O4, and g-C3N4/Fe3O4/ZnO2023In: Materials Today Communications, ISSN 2352-4928, Vol. 37, article id 107340Article in journal (Refereed)
    Abstract [en]

    In this study, the photocatalytic activity of g-C3N4/Fe3O4/ZnO, g-C3N4/Fe3O4, and g-C3N4 catalysts when exposed to visible light was thoroughly examined. We deliberately take advantage of visible light potential to create electron-hole (e/h+) pairs with exceptional lifetimes. The g-C3N4/Fe3O4/ZnO nanocomposite stands out among the tested catalysts as the undisputed champion thanks to its excellent degrading efficiency. This remarkable result is due to the formation of an interface between g-C3N4 and ZnO, which increases the response to visible light and makes it easier to separate photo-induced electrons and holes, completely. Furthermore, the nanocomposite including Fe3O4 phase addressed the challenge of catalyst recovery and magnetic separation from the solution.

  • 48.
    Zulfiqar, Waqas
    et al.
    Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Faisalabad, Pakistan; Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
    Alay-e-Abbas, Syed Muhammad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Faisalabad, Pakistan.
    Improved Thermodynamic Stability and Visible Light Absorption in Zr+X Codoped (X = S, Se and Te) BaTiO3 Photocatalysts: A First-Principles Study2022In: Materials Today Communications, ISSN 2352-4928, Vol. 32, article id 103867Article in journal (Refereed)
    Abstract [en]

    Band gap tuning of titanium based perovskite oxides through chalcogen doping is an attractive avenue for realizing visible light driven photocatalysis for hydrogen production. Unfortunately, accommodating a chalcogen atom at an O-site of BaTiO3 is thermodynamically challenging owing to large differences in the atomic radii and electronegativities of oxygen and chalcogen atoms. In the present study we employ first-principles density functional theory calculations to examine the influence of Zr codoping on the structural, thermodynamic, opto-electronic properties and photocatalytic performance of X-doped (X = S, Se and Te) BaTiO3 systems. The atomic structure and energetic properties are computed using SCAN meta-GGA functional of density functional theory, while the electronic and optical properties are computed using the TB-mBJ meta-GGA potential functional. Within the valid limits of the atomic chemical potentials, we find that chalcogen doping in BaTiO3 lattice would be experimentally difficult despite a clear reduction in the electronic band gap of this system useful for application in visible light driven photocatalysis. In order to improve the synthesis feasibility of X-doped BaTiO3 under oxygen-rich as well as oxygen-poor chemical environments, we propose Zr as a codopant at a Ti-site in X-doped BaTiO3 which improves the thermodynamic stability and also retains the reduction in the electronic band gap of BaTiO3 caused by the presence of chalcogen atom. Our results suggest that Zr+X (X = S, Se and Te) codoped BaTiO3 offers great opportunities as a practical photocatalysts for hydrogen production through overall splitting of the water molecule.

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