Shape memory behavior of a Ni3Ta alloy pre-deformed in compression

Shape memory behavior of a Ni3Ta shape memory alloy pre-deformed in compression up to 1% was studied by dilatometry. Dilatation characteristics were measured for non-deformed as well as pre-deformed polycrystalline and single crystal alloys from the room temperature to 950 °C. Shape recovery processes in the polycrystalline sample occur at room temperature where the martensite exists and then continue during the phase transformation from M → A. However, the major part of the compression pre-deformation is relaxed at high temperatures in the austenite region. This shape recovery process is associated with the elongation of the sample. Only small changes in length were found for the single crystal sample after pre-deformation and a single thermal cycle. Compression deformation increases the TWSME in the polycrystalline alloy and decreases the TWSME in the single crystal alloy.