The structure and physical-mechanical properties of Ti-Ni-Ta-based surface alloy synthesized on the NiTi-substrate through additive thin-film electron-beam method have been studied. The synthesis of the surface alloy was carried out by 30-fold alternation of operations of deposition of a dopant film (Ti60Ta40 (at.%), ~50 nm thick) and liquid-phase mixing of the film/substrate using a pulsed low-energy high-current electron beam. It was found that Ti-Ni-Ta-based surface alloy, whose thickness is ~1.8 μm, has an amorphous structure. It has been established that the surface alloy has ~2 and ~1.5 times higher values of microhardness HOP and elastic modulus EOP compared to the initial NiTi-substrate, but parameter of plasticity δh and shape recovery ratio η close to the substrate. It is shown that the nature of the change in physical-mechanical properties in Ti-Ni-Ta-based surface alloy and the transition zone depends on the number and thickness of the sublayers, as well as on the structural states of the phases in the sublayers. The evaluation of the mechanical compatibility of the surface alloy with the NiTi-substrate is given.

The physical-mechanical properties (microhardness, Young’s modulus, plasticity characteristic, shape recovery ratio) of the synthesized layers of Ti-Ni-Nb-based surface alloys of ~2 μm thickness, formed on the surface of NiTi alloy by the additive thin-film electron beam method were investigated by the instrumented indentation. It was found that the change in physical-mechanical properties in the synthesized surface alloys based on Ti-Ni-Nb is due to their layered structure. In particular, it is due to the thickness of the sublayers, their phase composition, and the structural states of the phases (nanocrystalline and amorphous). It was established that high strength and elastic-plastic parameters of the outer layer and a monotonic change in the physical-mechanical properties from the surface to TiNi substrate are provided in the surface Ti-Ni-Nb alloy with a lower volume fraction of the amorphous phase in the synthesized layers. It was found that the multilayer structure of the surface Ti-Ni-Nb alloy and the monotonically change in the physical-mechanical properties to the substrate ensure high mechanical compatibility of the synthesized layers of surface alloys with the TiNi substrate.