A first-principle assisted framework for designing high elastocaloric Ni–Mn-based magnetic shape memory alloy

A large adiabatic temperature change (∆Tad) is a prerequisite for the application of elastocaloric refrigeration. Theoretically, a large volume change ratio (∆V/V0) during martensitic transformation is favorable to enhance ∆Tad. However, the design or prediction of ∆V/V0 in experiments is a complex task because the structure of martensite changes simultaneously when the lattice parameter of austenite is tuned by modifying chemical composition. So far, the solid strategy to tailor ∆V/V0 is still urgently desirable. In this work, a first-principles-based method was proposed to estimate ΔV/V0 for Ni–Mn-based alloys. With this method, the substitution of Ga for In is found to be an effective method to increase the value of ΔV/V0 for Ni–Mn–In alloys. Combined with the strategies of reducing the negative contribution of magnetic entropy change (via the substitution of Cu for Mn) and introducing strong crystallographic texture (through directional solidification), an outstanding elastocaloric prototype alloy of Ni50(Mn28.5Cu4.5)(In14Ga3) was fabricated experimentally. At room temperature, a huge ∆Tad of -19 K and a large specific adiabatic temperature change of 67.8 K/GPa are obtained. The proposed first-principle-assisted framework opens up the possibility of efficiently tailoring ∆V/V0 to promote the design of advanced elastocaloric refrigerants.