Thermal and stress-induced martensitic transformations in NiFeGa single crystals under tension and compression

Heat treatment and stress state effects on the martensitic transformation in [0 0 1] and [1 2 3] oriented single crystal Ni54Fe19Ga27 alloys are determined. Characteristic temperatures increase for longer aging times and higher hold temperatures. The non-aged [0 0 1] crystals exhibit the smallest stress hysteresis and lowest critical stress in tension. The experimental results are interpreted based on the role of ordering and the second phase on changes in transformation temperatures and hysteresis.