Shape Recovery Forces of Ti - Ni - Cu Shape Memory Alloys
허경철Gyeong Cheul Hur, 김유영Yoo Young Kim, 남태현Tae Hyun Nam
Abstract
Shape recovery force of Ti-50.2Ni and Ti-(50-X)Ni-XCu(at%)(X=5-20) shape memory alloys was measured by means of constant temperature tensile tests. Shape recovery force is almost independent of deformation temperature when deformation was made at temperatures below martensitic transformation start temperarure, Ms. However, it decreases significantly with rising deformation temperature when deformation was made at temperatures above Ms. In Ti-50.2Ni and Ti-45Ni-5Cu alloys whose transformation behaviour is B2(cubic)-B19`(monoclinic), shape recovery force increases with increasing prestrain from 2% to 4%, while keeps almost constant in Ti-Ni-Cu alloys whose Cu-content is above 10at% in which transformation occurs from B2 to B19(orthorhombic). The maximum shape recovery force decreases with increasing Cu-content.