The Effect of Thermomechanical Treatment on the Structure and Mechanical Properties of the Ti49.5Ni50.5 Shape-Memory Alloy

The effect of thermomechanical treatment on the structure and phase transformations of the Ti–50.5 at % Ni shape-memory alloy was studied. The data on the specific features of mechanical properties and character of fracture in the initial ultrafine-grained (UFG) alloy were gained by tension tests in combination with optical and electron microscopy and X-ray diffraction analysis. The UFG alloy structure was created by multipass plastic rolling deformation. The alloy was established to have high levels of its mechanical properties (ultimate strength of up to 1400 MPa at a relative elongation of more than 25%) due to the revealed effect of a complex reaction: recrystallization with the formation of a UFG structure and associated highly dispersed heterogeneous decomposition.