Durable elastocaloric alloys for wide-temperature range cooling

Abstract

Solid-state elastocaloric refrigeration offers a zero global warming potential (GWP) potential alternative to vapor-compression systems, and also enabling efficient cooling for cryogenic applications, yet its practical deployment is constrained by the absence of high-performance elastocaloric materials with wide operational windows and extreme durability. Here, we report a polycrystalline titanium alloy (Ti-24Nb-4Zr-8Sn in wt%, Ti2448) that achieves elastocaloric effect with quasi-adiabatic temperature changes up to 4.2 K, across a wide temperature range from 298 to 38 K, with extrapolated reaching down to 1.59 K. The observed elastocaloric effect is attributed to a competition between phase transition entropy of BCC and orthorhombic phases and elastic entropy, as revealed by in-situ neutron and synchrotron X-ray diffractions. Critically, Ti2448 exhibits a tensile fatigue life exceeding 500,000 cycles at 137 K and combined with much higher corrosion resistance than commercial Ti-Ni alloys, the prototype of elastocaloric materials. Unlike complex single-crystal counterparts limited to lab-scale synthesis, Ti2448 leverages industrial-scale manufacturability, enabling its deployment as a candidate material for wide temperature cooling.