DEFORMATION AND TRANSITION BEHAVIOR ASSOCIATED WITH THE R-PHASE IN Ti-Ni ALLOYS.

Abstract

Deformation behavior associated with the R-phase (rhombohedral phase) transition and the subsequent martensitic transforation was studied systematically in Ti-Ni alloys by tensile testing over a wide temperature range covering below M//f to above T prime //R (22 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 thermomechanical treatment. As a result precipitates and/or dislocations were revealed in the specimens in which the R-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 the R-phase transition and the martensitic transformation.