Superelasticity by introductions of Cr into the Ti-Zr-Nb-Sn strain glass alloy toward the elastocaloric application

Abstract

In this study, new superelastic Ti-18Zr-9 Nb-2Sn-(1−2)Cr (at%) alloys were fabricated by an arc melting method and annealed at different temperatures for 0.6 ks to obtain β-titanium elastocaloric materials. Their phase constituents, strain glass transition behavior, superelasticity, and textural characteristics were analyzed by X-ray diffraction, dynamic mechanical response, tensile tests, and electron back-scattered diffraction, respectively. The strain glass transition behavior exhibited a dependence on the Cr doping content and annealing temperature: 1 at% Cr reduced the transition temperature T0 of the sample by about 50 K, while T0 decreased gradually from 242 K to 218 K with the annealing temperature. A highly dominant {111}β< 110 >β texture and high-density fine subgrains were obtained in the Ti-18Zr-9 Nb-2Sn-1.5Cr alloy annealed at 923 K. The sample had a superelastic strain of 3.80 % and critical stress of 520 MPa. Finally, a stable and reproducible adiabatic temperature change of 4.20 K was obtained at room temperature.