Temperature Dependence of Twinning Pseudoelasticity in Fe₃Ga Single Crystals

Abstract

Temperature dependence of twinning pseudoelasticity in D0₃-ordered Fe₃Ga single crystals was examined. In the crystals annealed in the D0₃ single-phase region, 2.2^T-type pseudo-twins were frequently introduced during loading at and below room temperature. Since the pseudo-twins had a high energy compared with a perfect twin, the untwinning took place during unloading to decrease their energy resulting in the twinning pseudoelasticity. Moreover, the twinning pseudoelasticity became more dominant with decreasing temperature, in contrast to that based on dislocation motion. In particular, high strain recovery during unloading was observed even at −180°C. Furthermore, the formation and annihilation stresses of the pseudo-twins were almost constant irrespective of deformation temperature at and below 100°C. This means that high driving force for the twinning pseudoelasticity was preserved even at low temperatures.