Temperature Dependence of Pseudoelasticity and Shape Memory Effect in Fe₃Ga Single Crystals with D0₃ Structure

Abstract

Pseudoelastic behavior and shape memory effect in D0₃-ordered Fe–24.4at%Ga single crystals deformed at different temperatures were investigated focusing on the microstructure and dislocation configuration. High strain recovery ratios more than 80% could be obtained at temperatures between −100 and 100°C. In particular, perfect pseudoelasticity appeared in the crystals deformed at room temperature. During unloading, antiphase boundaries (APB) left behind 1/4‹111› superpartial dislocations pulled back the superpartials resulting in the pseudoelasticity. In addition, Fe₃Ga single crystals compressed at −150°C demonstrated shape memory effect during heating to room temperature. On the other hand, the recovery ratio decreased with increasing deformation temperature up to 300°C and remained constant at about 10%. The L1₂ phase precipitating during deformation, dislocation configuration associated with 1/4‹111› superpartials connected by two kinds of APB and relaxation of the APB were found to strongly influence the pseudoelasticity and shape memory effect in Fe₃Ga single crystals.