Gd-Dy-Al-Co bulk metallic glasses with large magnetic entropy change and refrigeration capacity

Novel Gd_56-xDy_xAl₂₄Co₂₀ (x = 0, 14, 17) bulk metallic glasses (BMGs) were prepared by copper mold casting. They exhibit magnetic entropy changes (ΔS_M) comparable to that of Gd₅₃Al₂₄Co₂₀Zr₃ BMG and crystalline Gd. Moreover, these glassy alloys have broad entropy change peaks, resulting in the refrigeration capacities of 751.4 J kg^-1, 702.8 J kg ^-1, and 682.3 J kg^-1 for Gd₅₆Al ₂₄Co₂₀, Gd₄₂Dy₁₄Al ₂₄Co₂₀, and Gd₃₉Dy₁₇Al ₂₄Co₂₀ at 5 Tesla. The large magnetocaloric effect makes these BMGs attractive candidates as magnetic refrigerant in temperature range of 50-140 K. It is also found that the Curie temperature of this kind of metallic glass linearly declines with the increase of Dy. The ΔS_M of metallic glasses reaches maximum at certain content of Dy. These findings are expected to provide a meaningful guidance for the composition design of rare earth based glassy alloys for refrigeration application.