Abstract We report direct evidence of tensile superelasticity in micron-sized specimens of a Fe–Ni–Co–Al–Ti–B shape memory alloy. Dog-bone-shaped micro-tensile specimens were fabricated by focused ion beam milling and tested in situ under a scanning electron microscope. The corrected stress–strain curves exhibit clear hysteresis loops and superelastic strains up to ~ 4.5%, demonstrating stable transformation-mediated superelasticity at the micron scale. Both the critical transformation stress (~ 1.2 GPa) and the stress hysteresis (~ 1 GPa) are greatly enhanced compared with the bulk, reflecting pronounced size effects. These findings extend size-dependent transformation studies to precipitation-strengthened Fe-based shape memory alloys and highlight their potential for microactuators and other small-scale functional applications.
Xu et al. (Tue,) studied this question.