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

Abstract

• An efficient first-principle-based computational method to predict ΔV/V 0 is proposed • The substitution of Ga for In is beneficial to increase ΔV/V 0 and ∆S vib • The substitution of Cu for Mn is beneficial to reduce ∆M and ∆S mag • A large transformation entropy change is obtained of the proposed alloy • The studied alloy exhibits excellent elastocaloric properties at room temperature A large adiabatic temperature change (∆ T ad ) is a prerequisite for the application of elastocaloric refrigeration. Theoretically, a large volume change ratio ( ∆V/V 0 ) during martensitic transformation is favorable to enhance ∆ T ad . However, the design or prediction of ∆V/V 0 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/V 0 is still urgently desirable. In this work, a first-principles-based method was proposed to estimate ΔV/V 0 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/V 0 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 Ni 50 (Mn 28.5 Cu 4.5 )(In 14 Ga 3 ) was fabricated experimentally. At room temperature, a huge ∆ T ad 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/V 0 to promote the design of advanced elastocaloric refrigerants.