Study on constraint transformation behavior of TiNi alloy

The constraint transformation behavior of 7% strained TiNi alloy was investigated, and the experimental results show that the recovery stress formed at the first constraint transformation thermal cycling is the highest, and then decreases with increasing the constraint transformation thermal cycling number. It is indicated that the recovery strain of deformed TiNi alloy is decreased with increasing the constraint transformation thermal cycling number by forming the internal plastic deformation, which results in the decrease of the recovery stress. The reverse transformation start temperature A(s)' of the deformed TiNi alloy at the first constraint transformation thermal cycling is elevated to a higher temperature, but it nearly returns to the original value of undeformed one at subsequent constraint transformation thermal cycling. and does not change with increasing the constraint transformation thermal cycling number.