Ti-content and annealing temperature dependence of transformation behavior of TiXNi(92-XCu8 shape memory alloys

Ti-content and annealing temperature dependence of the transformation behavior of TiXNi(92-X)Cu8.0 (at,%) (X = 49.0–5l.0) alloys was investigated by varying the annealing temperature from 573 to 1273 K. It was found that the peak temperature of B2–B19 transformation (O*) increases with increasing annealing temperature from 673 to 873 K for all of the alloys. With annealing at temperatures above 873 K, the influence of annealing on O* depends on Ti-content. In the range of 50.4–51.0 at.% Ti, O* shows little dependence on annealing temperature. In the range of 49.3–50.2 at.% Ti, O* firstly decreases and then keeps constant with increasing annealing temperature. For the alloy of 49.0 at.% Ti, O* continuously decreases with increasing annealing temperature from 873 to 1273 K. On the basis of the above data, a partial phase diagram of Ti-Ni-8.0Cu (at.%) was proposed. The transformation hysteresis also showed unique Ti-content and annealing temperature dependence.