Actual Yield Stress in Ti_49.3Ni_50.7 (at.%) Alloy in the State As Received from the Manufacturer

The development of inelastic and plastic strains is studied for Ti_49.3Ni_50.7 (at.%) alloy samples with the structure of high-temperature B2 phase in the state as received from the manufacturer under torsion. It has been established that when the strain of the samples, specified by torsion, is equal to 10.6%, the value of the accumulated plastic strain is 0.35%. Therefore, the actual yield stress of the Ti_49.3Ni_50.7 (at.%) alloy samples is localized at the end of the pseudo-yield plateau on the stress-strain dependence rather than at the end of the strain hardening stage, as previously thought. The results presented in the work should be taken into account in the practical use of the alloy with this composition as products for technical and medical purposes that experience tensile, bending, and torsional deformations.