Effect of Ti-Ni-Ta-Based Surface Alloys on the Deformation Behavior and Superelasticity of Nickel Titanium Alloy Under Torsion Tests

The studies have been conducted on the effect of Ti-Ni-Ta-based surface alloys on the deformation behavior and superelasticity of TiNi alloy under torsional tests. The synthesis of the Ti-Ni-Ta-based surface alloys was carried out by 20- and 30-fold alternation of operations of deposition of a dopant film (Ti70Ta30 and Ti60Ta40 at.%, respectively, ~50 nm thick) and liquid-phase mixing of the film/substrate using an electron-beam. Based on the obtained results, the following conclusions were made. It has been found that the electron-beam synthesis of the Ti-Ni-Ta-based surface alloys does not have a critical effect on the integral inelastic properties of the TiNi-substrate, but on the contrary, leads to an increase in the strength characteristics, and to an increase in the accumulation and recovery of inelastic deformation. Subsequent heating of TiNi samples with Ti-Ni-Ta-based surface alloys to the temperature T ≅ 323 K after the cyclic torsional tests leads to recovery of the accumulated deformation.