Deformability and nanostructuring of TiNi shape-memory alloys during electroplastic rolling

Electropulse current effects during cold rolling on deformability, nanostructure formation and mechanical behavior in coarse-grained (CG) and ultrafine-grained (UFG) TiNi alloys enriched by nickel are investigated. An ultrafine-grained sample processed by cold rolling with current has a fracture strain (e = 1.91) which is higher than that without a current (e = 0.59). As a result of cold rolling with a current and a subsequent annealing at 400–450 °C, nanostructure is formed in both alloys, which leads to a significant enhancement of yield and ultimate stresses. It is shown that the efficiency of electroplastic rolling depends on the purity of the alloys.