Heterogeneous GdTbDyCoAl high-entropy alloy with distinctive magnetocaloric effect induced by hydrogenation

Developing novel magnetocaloric materials is of great significance for the applications of magnetic refrigeration. In this study, we designed a heterogeneous rare-earth-based high-entropy alloy (HEA) comprising amorphous matrix, local crystal-like cluster and nanocrystalline dihydride with average size of 7.5 nm through isothermal hydrogenation. This heterogeneous structure can significantly tune the magnetocaloric effect of alloy. After hydrogenation, the predominant exchange interaction transforms from ferromagnetic to antiferromagnetic with the disappearance of spin-glass-like behavior, and a complete second-order magnetic transition is obtained. Compared with the Gd20Tb18Dy18Co20Al24 high-entropy metallic glass with a small number of nanocrystals, the maximum magnetic entropy change of the hydrogen-containing HEA is increased from 8.8 to 13.6 J kg(-1) K-1 under applied magnetic field change of 5 T accompanying unobvious hysteresis and decreased magnetic transition temperature from 59 to 8 K, which is more promising as magnetic refrigerant at cryogenic temperature. This work provides a novel concept of designing heterogeneous structure in terms of special cluster and preferential nanocrystalline to modulate the properties of metallic glasses. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.

Automated summary

This study developed a heterogeneous high-entropy alloy with a designed structure through isothermal hydrogenation, which effectively modulated the magnetocaloric effect of the alloy. The hydrogenated alloy exhibited a complete second-order magnetic transition and transformed its predominant exchange interaction from ferromagnetic to antiferromagnetic. Compared with other high-entropy alloys, the hydrogen-containing alloy showed a higher magnetic entropy change and a lower magnetic transition temperature, making it more suitable as a magnetic refrigerant at cryogenic temperatures.