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Functional Metallic Glasses
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For decades, Metallic Glass, with its isotropic featureless structure while exhibiting outstanding mechanical properties was possible only at a high rate of quenching and with at least one dimension in the submicron regime.  This limitation was overcome with the discovery of Bulk Metallic glasses, BMGs, containing three or more elements following the additional two empirical rules of optimum geometric size differences and negative energy of mixing among the constituent elements. Since then thousands of Fe-, Ni-, Al-, Mg-, Ti- based BMGs have been discovered and comprehensively investigated mainly by groups in Japan and USA. Yet the discovery of new combinations of elements for BMGs is alchemy. We do not know with certainty which element when added will make possible a transition from being a ribbon to a bulk rod.

   In this thesis we report a discovery of castable BMGs rods on substitution of Fe by nickel in an alloy of FeBNb which could otherwise have been only melt-spun into ribbons.  For example, we find that substitution of just 6 at.% of Fe raises the glass forming range, GFA, to as much as ∆Tx =40K while the other parameters for GFA like Trg, γ, and δ reach enhanced values 0.57, 0.38, and 1.40 respectively.  Furthermore, the electrical conductivity is found to increase by almost a factor of two.  Magnetically it becomes softer with coercivity 260mOe which further reduces to much lower values on stress relaxation.  Ni does not seem to carry a magnetic moment while it enhances the magnetic transition temperature linearly with Ni concentration. We have investigated the role of Ni in another more stable BMGs based FeBNbY system in which case ∆Tx becomes as large as 94K with comparable enhancement in the other GFA parameters. Due to the exceptional soft magnetic properties, Fe-based bulk metallic glasses are considered potential candidate for their use in energy transferring devices. Thus the effect of Ni substitution on bulk forming ability, magnetic and electrical transport properties have been studied for FeBNb and FeBNbY alloy systems. The role of Ni in these systems is densification of the atomic structure and its consequence.

We have exploited the superior mechanical properties of BMGs by fabricating structures that are thin and sustainable.  We have therefore investigated studies on the thin films of these materials retaining their excellent mechanical properties. Magnetic properties of FeBNb alloy were investigated in thin films form (~200-400nm) in the temperature range of 5-300K. These Pulsed Laser deposited amorphous films exhibit soft magnetism at room temperature, a characteristic of amorphous metals, while they reveal a shift in hysteresis loop (exchange anisotropy, HEB=18-25Oe), at liquid helium temperature. When thickness of films is reduced to few nanometers (~8-11nm), they exhibit high transparency (>60%) in optical spectrum and show appreciably high saturation Faraday rotation (12o/μm, λ= 611nm). Thin films (~200-400nm) of Ni substituted alloy (FeNiBNb) reveal spontaneous perpendicular magnetization at room temperature. Spin-reorientation transition was observed as a function of film thickness (25-400nm) and temperature (200-300K), and correlated to the order/disorder of ferromagnetic amorphous matrix as a function of temperature. These two phase films exhibits increased value of coercivity, magnetic hardening, below 25K and attributed to the spin glass state of the system.

   Using the bulk and thin films we have developed prototypes of sensors, current meters and such simple devices although not discussed in this Thesis.                                     

   Ti-based bulk metallic glasses have been attracting significant attention due to their lower density and high specific strength from structural application point of view. High mechanical strength, lower values of young’s modulus, high yield strength along with excellent chemical behaviors of toxic free (Ni, Al, Be) Ti-based glassy metals make them attractive for biomedical applications. In the present work, toxic free Ti-Zr-Cu-Pd-Sn alloys were studied to optimize their bulk forming ability and we successfully developed glassy rods of at least 14mm diameter by Cu-mold casting. Along with high glass forming ability, as-casted BMGs exhibit excellent plasticity. One of the studied alloy (Ti41.5Zr10Cu35Pd11Sn2.5) exhibits distinct plasticity under uniaxial compression tests (12.63%) with strain hardening before failure which is not commonly seen in monolithic bulk metallic glasses.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xiv, 60 p.
Keyword [en]
Bulk Metallic glasses, glass forming ability, soft magnetism, thin films, magnetic properties, magnetic hardening, plasticity, biocompatibility
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-101901ISBN: 978-91-7501-476-0 (print)OAI: oai:DiVA.org:kth-101901DiVA: diva2:549808
Public defence
2012-09-21, V2, Teknikringen 76, 2tr, Stockholm, 14:00 (English)
Opponent
Supervisors
Projects
Hero-m
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-19Bibliographically approved
List of papers
1. The observation of surface softening in Fe-based metallic glass
Open this publication in new window or tab >>The observation of surface softening in Fe-based metallic glass
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2011 (English)In: Mater. Res. Soc. Symp. Proc. Vol. 1300, Materials Research Society, 2011, 74-78 p.Conference paper, Published paper (Refereed)
Abstract [en]

Depth sensing nano-indentation investigations have been performed to determine the radial dependence of the hardness through the cross section of a Fe-based bulk glassy rod. We have found the hardness of the material decreases along radius from the center to the outermost surface. This phenomenon is attributed to the ‘cooling rate induced surface softening’.  Furthermore, a significant change (~15 %) in elastic modulus is noticed along the radius as well. 

Place, publisher, year, edition, pages
Materials Research Society, 2011
Series
Materials Research Society Symposium Proceedings, ISSN 0272-9172 ; 1300
Keyword
Bulk Metallic Glasses, Nano-indentation, Surface softening, Mechanical properties
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101828 (URN)10.1557/opl.2011.399 (DOI)2-s2.0-84859057949 (Scopus ID)
Conference
Materials Research Society (MRS), 2011
Projects
Hero-m
Funder
VINNOVA
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2017-04-28Bibliographically approved
2. The effect of Ni-substitution on physical Properties of Fe72-xB24Nb4Nix Bulk Metallic Glassy Alloys
Open this publication in new window or tab >>The effect of Ni-substitution on physical Properties of Fe72-xB24Nb4Nix Bulk Metallic Glassy Alloys
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2011 (English)In: MRS Proceedings, Volume 1300, 2011, Materials Research Society, 2011Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

We have succeeded in producing bulk metallic glass by partial substitution of Fe with Ni in Fe-B-Nb alloys which could otherwise be only melt spun into amorphous ribbons. Substitution by Ni in the Fe72-xB24Nb4Nix alloys with (x ~2, 4, 6, 8, 10, 12 and 14) improves the glass forming ability of the materials and as a result rods of same compositions can be fabricated. Magnetically the BMG alloys remain soft with coercivity below 500mOe. However, the electrical resistivity of the system decreases significantly by as much as a factor of two with the increase of Ni concentration, and becomes more metallic like with a positive temperature coefficient. 

Place, publisher, year, edition, pages
Materials Research Society, 2011
Keyword
metal, magnetic, amorphous
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101829 (URN)10.1557/opl.2011.304 (DOI)2-s2.0-84859062782 (Scopus ID)
Conference
Materials Research Society, April 25 - 29, 2011, Moscone West Convention Center - San Francisco, California
Projects
Hero-m
Funder
VINNOVA
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2016-12-23Bibliographically approved
3. Soft magnetic Fe-Ni-B-Nb glassy metals
Open this publication in new window or tab >>Soft magnetic Fe-Ni-B-Nb glassy metals
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

The influence of partial substitution of Fe with Ni on Fe72-xNixB24Nb4 glassy alloys with 0≥ x ≤14 on glass forming ability, thermal stability, magnetic behavior and electrical transport properties was investigated systematically. Ni substituted alloys were found with improved glass forming ability and glassy rods of at least half millimeter were fabricated for all studied compositions. Saturation magnetization decreased linearly from 133 to 115emu/g as a result of substitution for Ni concentration of 2-14%. Contrary to that Curie temperature increased linearly with substitution and as a result, highest value of 606K was achieved for 14% of Ni. As-quenched ribbon samples showed very soft magnetic behaviors with lowest coercivity of ~0.26Oe for alloy system of Ni~8%. Effect of thermal treatment on structural evolution as well as on magnetic properties was investigated for glassy alloy of Fe60Ni12B24Nb4 and a direct correlation was found. Low-field magnetic study revealed magnetic softening behavior followed by magnetic hardening and was attributed to structure relaxation and partial devitrification into nanocrystalline state of the amorphous precursors. Electrical transport properties of as-quenched glassy ribbons were found rather weak temperature dependent with positive temperature coefficient of resistivity in temperature range of 77-300K. Electrical resistivity of the studied glassy alloy was observed to decrease significantly by factor of two with the addition of Ni content for x~2- 14. 

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101831 (URN)
Projects
Hero-m
Funder
Vinnova
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved
4. Magneto-Thermo-Gravimetric technique to investigate the structural and magnetic properties of Fe-B-Nb-Y Bulk Metallic Glass
Open this publication in new window or tab >>Magneto-Thermo-Gravimetric technique to investigate the structural and magnetic properties of Fe-B-Nb-Y Bulk Metallic Glass
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2009 (English)In: 13TH INTERNATIONAL CONFERENCE ON RAPIDLY QUENCHED AND METASTABLE MATERIALS, 2009, 012074- p.Conference paper, Published paper (Refereed)
Abstract [en]

Magneto-thermo-gravimetric (MTG) technique is highly informative about the changes in the magnetic state, as well as structural changes in a system, which cannot be often noticed in calorimetric measurements. We demonstrate the versatility of this technique in determining the magnetic transition temperature, and the subsequent crystallization process in a (Fe(0.72)B(0.24)Nb(0.04))(95.5)Y(4.5) Bulk Metallic Glass (BMG). MTG and DSC analyses were carried out at the heating rate of 0.67 K/s from RT similar to 1170 K. As a result of the repeated MTG measurements, a magnetic 2(nd) amorphous phase was observed in the BMG sample, which could be the first measurement for the Magnetic Short Range Ordering (MSRO). Consequently, the MTG measurement is proved as the most convenient method for determining the various structural and magnetic transitions in a glassy material.

Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 144
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101991 (URN)10.1088/1742-6596/144/1/012074 (DOI)000271827100074 ()2-s2.0-80052821307 (Scopus ID)
Conference
13th International Conference on Rapidly Quenched and Metastable Materials, AUG 24-29, 2008, Dresden, GERMANY
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-06 Last updated: 2012-09-06Bibliographically approved
5. Effect of Ni-substitution on glass forming ability, mechanical, and magnetic properties of FeBNbY bulk metallic glasses
Open this publication in new window or tab >>Effect of Ni-substitution on glass forming ability, mechanical, and magnetic properties of FeBNbY bulk metallic glasses
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2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 1, 013505- p.Article in journal (Refereed) Published
Abstract [en]

We present a method to identify bulk glass forming ability by partial substitution of Fe by Ni in FeBNbY based amorphous alloy ribbons and as a consequence obtain enhanced mechanical and soft magnetic properties of bulk glassy rods of diameter as large as 4.5 mm. A detailed investigation of thermal, mechanical, and magnetic properties of (Fe0.72-x NixB0.24Nb0.04)(95.5)Y-4.5 alloys (with x similar to 0.02, 0.04, 0.06, 0.08, 0.1) was carried out. The supercooled regime (Delta T-x) and other glass forming parameters, e. g., reduced glass transition temperature (T-rg), the gamma (gamma) parameter, etc., were found to be enhanced due to the Ni substitution resulting in improvement of glass forming ability (GFA). The maximum values of such parameters (Delta T-x similar to 94 K, T-rg similar to 0.644, and gamma similar to 0.435) were obtained for the alloy with x similar to 0.06, making it possible to cast cylindrical rods with 4.5 mm diameter for this composition. Nanoindentation studies on glassy rods also point out that (Fe0.66Ni0.06B0.24Nb0.04)(95.5)Y-4.5 alloy exhibit the maximum value of hardness (H similar to 12 GPa) as well as elastic modulus (E similar to 193 GPa) among all of these samples. In addition to these, that particular sample shows the lowest room temperature coercivity (H-c similar to 210 mOe). By annealing at 823 K, H-c can be further reduced to 60 mOe due to its structural relaxation. We attribute the improved soft magnetic and mechanical properties of as-quenched (Fe0.66Ni0.06B0.24Nb0.04)(95.5)Y-4.5 alloy to higher packing density attained due to its large glass forming ability.

Keyword
Alloys, Amorphous alloys, Magnetic properties, Mechanical properties, Niobium
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101835 (URN)10.1063/1.4772753 (DOI)000313329000022 ()2-s2.0-84872089597 (Scopus ID)
Projects
Hero-m
Funder
Vinnova
Note

QC 20120906. Updated from manuscript to article in journal.

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2017-12-07Bibliographically approved
6. Exchange bias in amorphous Fe-B-Nb thin films
Open this publication in new window or tab >>Exchange bias in amorphous Fe-B-Nb thin films
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Amorphous thin films of Fe-B-Nb alloy prepared by Pulse Laser Deposition (PLD) have been studied for their magnetic properties. Films of different thicknesses (200-400nm) were cooled from room temperature down to 5K at remnant state of magnetization (MR) and inplane magnetic hysteresis loops were measured at different temperatures (5-300K). At room temperature, soft ferromagnetism was observed while hysteresis loops revealed a shift from origin by giving rise to the exchange bias anisotropy at liquid helium temperatures. The magnitude of this shift, anisotropy, decreased exponentially by increasing temperature and fully disappears at ~30K. The significant shift of the hysteresis loops observed at liquid helium temperatures after cooling from MR and strong irreversibility between zero field cooled (ZFC) and field cooled (FC) magnetization curves probed under different magnetic fields (5-20Oe) reveal the presence of spin-disorder phase, which influences significantly the low temperature behavior in the present amorphous thin films. 

National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-101836 (URN)
Projects
Hero-m
Funder
Vinnova
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved
7. Magneto-Optical properties of amorphous Fe-B-Nbthin films
Open this publication in new window or tab >>Magneto-Optical properties of amorphous Fe-B-Nbthin films
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Optically highly transparent, soft ferromagnetic thin films of Fe-B-Nb alloy grown on quartz by Pulse Laser Deposition (PLD) were investigated for structural, optical and magneto-optical properties.  All deposited films revealed fully amorphous structure with very uniform thickness and surface morphology.  Optical transmittance of 8 and 11nm thick films were found more than 60% over the entire visible regime (400-700nm). Verdet constant (V) and saturation Faraday rotation angle (θf) of studied films were increased linearly as a function of wavelength (λ) and  considered appreciably high as compared to the reported  magneto-optic materials, for example, 11nm thick film showed θf = 11.8deg/μm and V=21.4deg/Oe cm at λ=611nm. The combination of optical and magneto-optical properties with state of art fabrication process makes this kind of amorphous films interesting for optical telecommunication technology. 

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-101837 (URN)
Note

Qc 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved
8. Spin-Reorientation Transition in Fe-Ni-B-Nb thin films
Open this publication in new window or tab >>Spin-Reorientation Transition in Fe-Ni-B-Nb thin films
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Spontaneous perpendicular magnetization manifested by transcritical loops and stripe domain magnetic pattern have been observed for nanocrystalline film (~408nm) of Fe-Ni-B-Nb alloy grown by pulse laser deposition (PLD) which, otherwise, could not be seen for thinner films (≤100 nm) and at low temperatures (≤225K). Thermal treatment of thicker films (408nm) was found to affect the global magnetic behaviors by transforming transcritical loops to simple square type. Temperature dependence of magnetization M (T) and AC susceptibility measurement revealed that intergranular amorphous matrix gets magnetically order/disorder as a function of temperature by giving rise to different global magnetic behaviors at different temperatures.    

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-101838 (URN)
Projects
Hero-m
Funder
Vinnova
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved
9. Low temperature magnetic hardening in nanocrystalline Fe-Ni-B-Nb thin films
Open this publication in new window or tab >>Low temperature magnetic hardening in nanocrystalline Fe-Ni-B-Nb thin films
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Low temperature magnetic properties of nanocrystalline FeNiBNb thin films grown by Pulse Laser Deposition (PLD) were investigated. Temperature dependence of magnetization M (T) revealed that weak ferromagnetic amorphous matrix gets magnetically order/disorder and as a consequence, system inters into different state of magnetization by giving rise to interesting global magnetic behaviors. Sample exhibits threefold coercive behavior with the evolution of temperature (5-300K).  Magnetic hardening was observed below 25K and attributed to evolution of spin-glass like state of the system. 

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-101839 (URN)
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved
10. Distinct Plasticity of Biocompatible Ti-Zr-Cu-Pd-Sn Bulk Metallic Glass
Open this publication in new window or tab >>Distinct Plasticity of Biocompatible Ti-Zr-Cu-Pd-Sn Bulk Metallic Glass
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

We have developed Ti-Zr-Cu-Pd-Sn bulk metallic glass without toxic elements which exhibits distinct plasticity (~12.6%) by revealing strain hardening before failure. Specimens performed under compression tests do not show any crystalline phases which usually enhance plasticity by branching or restricting the rapid propagation of shear bands. Along with excellent mechanical properties alloy exhibits appreciably high bulk forming ability, GFA, with large supercooled regime (~56K) and as a consequence cylindrical rods of at least 7mm were fabricated directly by Cu-mold casting. The combination of such mechanical properties and appreciably high bulk forming ability makes it a potential candidate for biomedical applications.   

National Category
Other Materials Engineering Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101840 (URN)
Projects
Hero-m
Note

Submitted to Applied Physics Letter (2012)

QS2012

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-07Bibliographically approved
11. Excellent bulk forming ability and high plasticity of Biocompatible Titanium based bulk metallic glasses
Open this publication in new window or tab >>Excellent bulk forming ability and high plasticity of Biocompatible Titanium based bulk metallic glasses
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

A series of bulk glassy alloys of Ti-Zr-Cu-Pd-Sn composition without toxic elements (Ni, Be, Al) were investigated that revealed excellent bulk forming ability by exhibiting large supercooled regions (ΔTx≥56K), high values of  reduced glass transition temperature (Trg ≥0.56) and the γ parameter (γ ≥ 0.39). As a consequence of large ΔTx≈70K glassy rods of at least 14mm diameter of Ti38.5Zr11.2Cu33.2Pd14.3Sn2.8 (Ti15) alloy were fabricated by direct Cu-mold casting. Uniaxial compressive test performed at room temperature showed high fracture strength (≥2070MPa) and good plasticity (≥5.8%) for all studied alloys. High bulk forming ability along with excellent plasticity (~6.8%) of Ti38.5Zr11.2Cu33.2Pd14.3Sn2.8 (Ti15) alloy as compare to other toxic free titanium based bulk metallic glasses (BMGs) makes it a potential candidate for biomedical application point of view. 

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101842 (URN)
Note

QC 20120906

Available from: 2012-09-06 Created: 2012-09-05 Last updated: 2012-09-06Bibliographically approved

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