| Changes in transformation behaviour and transformation temperatures of Ti-49Ni-1Cu and Ti-46Ni-4Cu shape memory alloys due to thermal cycling under constant load have been investigated by means of electrical resistivity measurements and thermal cycling tests under constant load. Transformation behaviour of thermomechanically treated Ti-49Ni-1Cu alloy was B2-B19` under the applied stress of 110 MPa and not changed with increasing thermal cycling number. On the other hand, under the applied stress of 50 MPa, it was B2-R-B19` and changed into B2-B19` with increasing thermal cycling number. In solution treated Ti-Ni-Cu alloys, the B2-B19` transformation start temperature decreased under the applied stress of 50 MPa, while was almost unchanged under the applied stress of 110 MPa with increasing thermal cycling number. In thermo-mechanically treated Ti-Ni-Cu alloys, however, it rised with increasing cycling number, irrespective of the amount of applied stress. |
|
