Shape memory effect and pseudoelasticity of TiPt

Martensitic transformation behavior and shape memory properties of Ti-50at%Pt were investigated using high-temperature X-ray diffractometry and loading-unloading compression tests. The structure of the parent and martensite phases was identified as B2 and B19, respectively. Changes in the lattice parameters of the martensite phase were investigated as a function of temperature. Applying the lattice parameter changes, the volume strain between B19 and B2 phases at 1473 K was estimated at 2.5%. The compression test was carried out at room temperature and at 1123 K. Strain was precisely measured using a strain gage for the test at room temperature and a CCD camera for the test at 1123 K. Strain recovery was observed during unloading at room temperature and at 1123 K, which was below the martensite temperature. Shape recovery was investigated for the samples tested at room temperature and at 1123 K by heating at 1523 K for 1 h. It was found that the strain recovery rate was 30-60% for the samples tested at room temperature and about 11% for the samples tested at 1123 K.