Superelasticity and Cryogenic Linear Shape Memory Effects of CaFe2As2

TL;DR

This paper reports a novel shape memory behavior in CaFe2As2, demonstrating superelasticity and cryogenic shape memory effects through a reversible phase transformation, with potential applications in cryogenic technologies and space exploration.

Contribution

It introduces a new shape memory material, CaFe2As2, exhibiting superelasticity and cryogenic shape memory effects via a reversible phase transformation mechanism.

Findings

Over 13% recoverable strain achieved

Cryogenic shape memory effects near 50 K observed

High yield strength over 3 GPa demonstrated

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 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.