The Effect of Low-Temperature Heat Treatment on the Superelasticity in Ti–50.6 at % Ni Single Crystals

Abstract

As a result of low-temperature aging at 573 K for 1.5 h of Ti–50.6 at% Ni [001]-oriented single crystals quenched from 1253 K, a high-strength state is obtained due to the precipitation of Ti₃Ni₄ nanoscale particles (d < 10 nm). The aging leads to the development of the B2–B19' martensitic transformation through an intermediate R phase, a reduction in the B19' martensite formation temperatures by 40–60 K, an increase in the strength properties of the B2 phase from 730 to 2100 MPa, and an extension of the superelasticity interval ΔT_SE in compression from ΔT_SE = 60 to 170 K (compared to quenched crystals).