Evaluation of residual stresses in Ti-Ni-Ta-Si surface alloy fabricated on TiNi-substrate subjected to electron-beam treatments

Abstract

In the work the Ti-Ni-Ta-Si surface alloy (SA) fabricated through additive thin-film electron-beam (ATF-EB) synthesis using TiNi substrate was studied by XRD method. The post synthesis treatments of the [Ti-Ni-Ta-Si]SA was carried out by pulsed low-energy (∼30 keV) high-current (∼25 kA) electron beam (LEHCEB) treatments at the same energy density (ES=1.7 J/cm2) and different numbers of pulses n=10 and 15. The numerical evaluations of residual stresses formed in the near-surface layer of TiNi substrate after ATF-EB synthesis of the [Ti-Ni-Ta-Si]SA were performed before and after additional LEHCEB treatments. The residual compressive stresses in the B2 (TiNi) phase, occurred due to the formation of the [Ti-Ni-Ta-Si]SA on TiNi substrates, show the value of σI∼–550 MPa. Additional LEHCEB treatments lead to the reduction of the value of residual stresses down to σI∼–450 MPa.