Tensile strain-induced softening of iron at high temperature
2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 16654Article in journal (Refereed) Published
In weakly ferromagnetic materials, already small changes in the atomic configuration triggered by temperature or chemistry can alter the magnetic interactions responsible for the non-random atomicspin orientation. Different magnetic states, in turn, can give rise to substantially different macroscopic properties. A classical example is iron, which exhibits a great variety of properties as one gradually removes the magnetic long-range order by raising the temperature towards its Curie point of T-C(degrees) = 1043 K. Using first-principles theory, here we demonstrate that uniaxial tensile strain can also destabilise the magnetic order in iron and eventually lead to a ferromagnetic to paramagnetic transition at temperatures far below T-C(degrees). In consequence, the intrinsic strength of the ideal single-crystal body-centred cubic iron dramatically weakens above a critical temperature of similar to 500 K. The discovered strain-induced magneto-mechanical softening provides a plausible atomic-level mechanism behind the observed drop of the measured strength of Fe whiskers around 300-500 K. Alloying additions which have the capability to partially restore the magnetic order in the strained Fe lattice, push the critical temperature for the strength-softening scenario towards the magnetic transition temperature of the undeformed lattice. This can result in a surprisingly large alloying-driven strengthening effect at high temperature as illustrated here in the case of Fe-Co alloy.
Place, publisher, year, edition, pages
2015. Vol. 5, 16654
Other Natural Sciences Physical Sciences
IdentifiersURN: urn:nbn:se:uu:diva-268399DOI: 10.1038/srep16654ISI: 000364383700001PubMedID: 26556127OAI: oai:DiVA.org:uu-268399DiVA: diva2:878510
FunderSwedish Research CouncilSwedish Research Council FormasEU, European Research CouncilSwedish e‐Science Research CenterGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyEU, European Research CouncilEU, European Research Council, TAMOP 4.2.4.A/2-11-1-2012-0001