Phase transformations of severely plastically deformed Ti–Ni–Pd high-temperature shape memory alloys

Severe plastic deformation of a Ti50Ni25Pd25 high-temperature shape memory alloy yields a nanoscale mixture of an amorphous phase and retained lamellae of the parent B19 martensite. The thermal stability of the deformed martensite is significantly enhanced. Upon heating, B2 austenite occurs within the martensite and by crystallization of the amorphous phase, concomitant with recovery and the formation of an ultrafine grained structure. In the small grains, the B2 austenite to B19 martensitic transformation is shifted to lower temperatures and incomplete.