Superelasticity and cryogenic linear shape memory effects of CaFe2As2

Date
2017-10-20
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Goldman, Alan
Sypek, John
Yu, Hang
Dusoe, Keith
Canfield, Paul
Drachuck, Gil
Patel, Hetal
Giroux, Amanda
Goldman, Alan
Kreyssig, Andreas
Canfield, Paul
Bud’ko, Serguei
Weinberger, Christopher
Lee, Seok-Woo
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Ames Laboratory
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Physics and Astronomy
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Ames LaboratoryPhysics and Astronomy
Abstract

Shape memory materials have the ability to recover their original shape after a significant amount of deformation when they are subjected to certain stimuli, for instance, heat or magnetic fields. However, their performance is often limited by the energetics and geometry of the martensitic-austenitic phase transformation. Here, we report a unique shape memory behavior in CaFe2As2, which exhibits superelasticity with over 13% recoverable strain, over 3 GPa yield strength, repeatable stress–strain response even at the micrometer scale, and cryogenic linear shape memory effects near 50 K. These properties are acheived through a reversible uni-axial phase transformation mechanism, the tetragonal/orthorhombic-to-collapsed-tetragonal phase transformation. Our results offer the possibility of developing cryogenic linear actuation technologies with a high precision and high actuation power per unit volume for deep space exploration, and more broadly, suggest a mechanistic path to a class of shape memory materials, ThCr2Si2-structured intermetallic compounds.

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