Transformation sequence in severely cold-rolled and annealed Ti50Ni50 alloy

Transformation sequence of Ti50Ni50 shape memory alloy after 35% cold-rolling and subsequent recrystallization annealing have been investigated. Four transformation sequences of Stages I–IV on different annealing conditions are proposed. Stage I corresponds to an incomplete transformation, whereas Stage II represents the four-step MST with two large and two small peaks associated with B2 → R → B19′ transformation of large grains in the specimen center and that of small grains near the rolling surface, respectively. Stages III and IV are the complete B2 ↔ R ↔ B19′ and B2 ↔ B19′ transformation sequences, respectively.