Effect of the Surface Oxide Layer on Shape Memory Effect and Superelasticity of [011]-Oriented Ti-50.1Ni Single Crystals

Effect of the surface oxide layer on shape memory effect (SME) and superelasticity (SE) after marforming (deformation in martensitic state, followed by annealing at 713 K for 0.5 h an inert helium gas dry air) was investigated Ti-50.1Ni (at.%) single crystals, oriented along [011]-direction, under compression. Quenched [011]-oriented crystals alloy experience a one-stage B2-B19′ transformation (MT) without SE Marforming leads to two-stage B2-R-B19′ MT creates conditions SE. A thin TiO2 170 nm thick formed sample upon air. In with layer, maximum value reached 4%, SME 2.4 2.6%, respectively. Appearance air: (i) reduces stresses B2-phase 50 MPa from Md 473 K; (ii) decreases Θ = dσ/dε 6.5 GPa 2.0 (iii) does not affect values.