Excellent elastocaloric and mechanical performance in Mn-doped Co-V-Ga as-cast polycrystalline alloy with simple preparation

With the rapid development of solid-state refrigeration technology, elastocaloric materials face higher re-quirements, such as a higher elastocaloric effect (eCE), better mechanical properties, and simpler and faster large-scale preparation. In this work, we propose a composition design strategy for Mn-doped Co-V-Ga shape memory alloys, which can enhance both the eCE and the mechanical properties. We combine first-principles calculations and experiments to demonstrate this strategy. Our results reveal that the lattice distortion caused by the difference in atomic radii produces a solid-solution-strengthening effect within the alloy, impeding dislocation motion and significantly improving the mechanical properties. Through composition optimization, the low-cost Co51.7V31.3Ga14.75Mn2.25 as-cast polycrystalline alloy exhibits a large adiabatic temperature change (ATad) of-11.2 K at room temperature, while its maximum compressive strength and strain can reach up to 1859 MPa and 26% at room temperature, respectively. Importantly, the alloy exhibits excellent cycle stability, and its ATad does not decay after 100 loading and unloading cycles, indicating that it has the potential for practical application. Further comparison with the annealed sample shows that the secondary defects deteriorate the ATad of the alloy. Our research provides an effective strategy for the simple, rapid and large-scale production of as-cast eCE alloys.