Atypical intrinsic Elinvar behavior of β Ti–22Nb–6Zr alloy in high and wide temperature range

The Elinvar behavior of Ti–22Nb–6Zr shape memory alloy was studied to determine the mechanism of such behavior and find the way to control this effect. The temperature dependences of elastic properties were studied using torsional pendulum experiments. The stability of phase composition was evaluated by X-ray diffraction analysis. Compression mechanical testing and classical atomistic simulations were used to confirm the obtained results on the macroscopic and atomic levels. The heating/cooling rate of ≥9 °C/min allows realization of the two-way Elinvar behavior in the 150–550 °C range with a temperature coefficient of f_r2 ∼10−5 °C−1; this behavior is stable, repeatable, and independent of the β-phase state, whether the alloy has a polygonized dislocation substructure or a recrystallized structure. The study concludes that the Elinvar behavior observed is an intrinsic property of BCC β-phase.