Magnetocaloric effect in rare earth-based bulk metallic glasses

Magnetocaloric effect (MCE) of rare earth-based bulk metallic glasses (BMGs) and the influences of applied field, structural change induced by microalloying, aging and crystallization on the MCE are systematically investigated. For all the as-cast alloys the magnetic entropy changes (−ΔSm) compare favorably with that of pure Gd metal, some are even better. Our results indicate that the BMGs and corresponding composites induced by partial crystallization be attractive candidate for magnetic refrigerants in Ericsson-cycle. Aging and partially crystallization of Gd-based BMGs lead to the reduction of both the transition temperature and the peak value of the magnetic entropy change. However, unusual table-like shapes of the MCE are observed for the crystallized samples over wide temperature range. Although the short-range structural change due to long time aging has observable effect on MCE, the structural change induced by microalloying has less influence on MCE compared with that of some crystalline materials. The possible reasons for the good MCE in these BMGs are discussed. It is found that the field dependence of magnetic entropy change follows a power law but the exponents near the transition temperature deviate from the mean field picture, and the random magnetic anisotropy has obvious effect on the field dependence of the magnetic entropy change.