Ti–Ni–Ta-based surface alloy synthesized on the TiNi-substrate through electron-beam method: structure and physical-mechanical properties

The structure and physical-mechanical properties of Ti–Ni–Ta-based surface alloy synthesized on the TiNi-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 (Ti$_{60}$Ta$_{40}$ (at.%), $\sim$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 $\sim$1.8 $\mu$m, has an amorphous structure. It has been established that the surface alloy has $\sim$2 and $\sim$1.5 times higher values of microhardness $H_{OP}$ and elastic modulus $E_{OP}$ compared to the initial TiNi-substrate, but parameter of plasticity $\delta_h$ and shape recovery ratio $\eta$ 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 TiNi-substrate is given.