The effect of hydrogen on shape memory effect and superelasticity in single-phase nickel titanium single crystals

The effect of hydrogen on temperature dependences of axial stresses $\sigma_{cr}(T)$, shape memory effect, and superelasticity of $[\bar{1}11]$-oriented Ti–50.7% Ni (at%) alloy single crystals has been studied under tensile strain in a single-phase state. It is established that the level of $\sigma_{cr}(M_s)$ and $\sigma_{cr}$(B2) stresses is determined by the state of hydrogen (in solid solution or titanium hydride particles) in the initial B2 phase. Superelasticity up to 2.0–2.5% occurs when hydrogen is present in the solid solution.