Mesoscopic-and macroscopic-level plastic deformation and fracture of ion-modified Ni50Ti40Zr10 alloy with the shape-memory effect

The influence of the ion-modified surface layer on the ductility, shape-memory effect, and mesoscopic structure of the surface of fracture was studied for Ni₅₀Ti₄₀Zr₁₀ alloy. It was found that ion implantation increases the microhardness of the surface layer about 1 μm thick but makes the bulk of the alloy more ductile. The mesoscopic structures of the fracture surfaces of the initial and implanted specimens suggest the formation of a specific layer immediately under the irradiated surface. Its thickness is a multiple of the grain size of the B2 phase. The mesorelief of this layer and its ductile properties differ from those of the nonirradiated specimens. After such a surface treatment, the shape memory effect parameters do not degrade, and the temperature cycling resistance is even improved.