Deformation and transition behavior associated with theR-phase in Ti-Ni alloys

Deformation behavior associated with theR-phase (rhombohedral phase) transition and the subsequent martensitic transformation was studied systematically in Ti-Ni alloys by tensile testing over a wide temperature range covering belowM _f to aboveT′ _R (>A_f). Since the deformation and transition characteristics showed a strong dependence on thermo-mechanical treatment and Ni-content, internal structures were examined by electron microscopy in specimens with various Ni-content and thermo-mechanical treatment. As a result precipitates and/or dislocations were revealed in the specimens in which theR-phase transition occurs. Based on the above results, the effects of thermo-mechanical treatment and Ni-content on the deformation and transition characteristics were clarified for both theR-phase transition and the martensitic transformation.