Ti-content dependence of shape memory characteristics of Ti-Ni-Cu alloy ribbons

摘要

Transformation behavior, shape memory characteristics and superelasticity of Ti-(40-x)Ni-10Cu(at%)(x=0～2) alloy ribbons were investigated. All ribbons showed the two-stage B2-B19-B19' transformation behavior. The temperature gap between Ms'(the B2-B19 transformation start temperature) and Ms(the B19-B19' transformation start temperature) was large(～ 40 K), which was ascribed to internal stress fields around dislocations introduced by melt spinning. Ti_2Ni particles were observed in Ti-39Ni-10Cu and Ti-38Ni-10Cu alloy ribbons, while they were not found in a Ti-40Ni-10Cu alloy ribbon. Volume fraction of Ti_2Ni particles increased from 3 % to 12 % with increasing Ti-content from 51 at% to 52 at%. Both Ms and Ms' decreased with increasing Ti-content, which was ascribed to formations of Ti_2Ni particles resulting in a decrease in Ti-content of matrix. Ti-(40-x)Ni-10Cu alloy ribbons showed perfect shape memory effect and superelasticity. The transformation hysteresis associated with the B2-B19 transformation was 6-10 K depending on Ti-content.