Unusual pseudoelastic behaviour of Fe3Ga shape memory alloys

Abstract

Pseudoelastic behaviour of Fe-23.8at%Ga single crystals compressed with different loading axes at room temperature was examined focusing on the activated deformation mode. In the crystals, {101} <111> slip and {211} <111> twin were mainly activated depending on the loading axis. Pseudoelastic behaviour of the crystals depended strongly on the deformation mode. If {101}<111> slip was operative, sole and paired 1/4<111> superpartial dislocations moved dragging antiphase boundaries (APB). During unloading, the APB pulled back the superpartials due to its tension resulting in pseudoelasticity. In contrast, twinning and untwinning of {211}<111> pseudo-twins also led to large strain recovery accompanying a serrated flow during loading and unloading. It is suggested the energy of the pseudo-twin interface was the driving force for the twinning pseudoelasticity. © 2009 IOP Publishing Ltd.