Physical-mechanical properties of surface layers of NiTi alloy depending on the number of pulses of electron beam

Abstract

The paper presents analysis of the research data on investigation of physical-mechanical properties of NiTi alloy after microsecond low-energy high-current pulsed electron beam treatment depending on the number of pulses of electron beam. Investigation of physical-mechanical properties (Young’s modulus EIT, dynamic hardness HIT, plasticity characteristic δН, and shape recovery ratio η) of NiTi surface before and after electron beam treatment was held by method of instrumented nanoindentation test. As a result electron beam modification of the surface of NiTi alloy leads to a change in the strength and plasticity characteristics in depth from the irradiation surface. The hardening of the surface layer reaches a depth of up to ∼500 nm at n = 5 (HIT ≈ 60 GPa), and up to ∼1000 nm at n=15 (HIT ≈ 100 GPa). At a depth of more than ∼1500 nm, the value of parameter of shape recovery ratio η decreased by ∼5–10%, which is due to the hardening of the modified surface layers of NiTi alloy.