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

A large adiabatic temperature change (Delta T-ad) is a prerequisite for the application of elastocaloric refrigeration. Theoretically, a large volume change ratio (Delta V/V-0) during martensitic transformation is favorable to enhance Delta T-ad. However, the design or prediction of Delta 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 Delta V/V-0 is still urgently desirable. In this work, a first-principles-based method was proposed to estimate Delta V/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 Delta V/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(Mn28.5Cu4.5)(In14Ga3) was fabricated experimentally. At room temperature, a huge Delta 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 Delta V/V-0 to promote the design of advanced elastocaloric refrigerants. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, a first-principles-based method was used to estimate Delta V/V-0 for Ni-Mn-based alloys, and the substitution of Ga for In was found to effectively increase the value of Delta V/V-0 for Ni-Mn-In alloys. By reducing the negative contribution of magnetic entropy change and introducing strong crystallographic texture, an outstanding elastocaloric prototype alloy, Ni-50(Mn28.5Cu4.5)(In14Ga3), was successfully fabricated, exhibiting a huge Delta T-ad of -19 K and a large specific adiabatic temperature change of 67.8 K/GPa at room temperature. The proposed first-principle-assisted framework opens up possibilities for efficient tailoring of Delta V/V-0 and the design of advanced elastocaloric refrigerants.