Design and fabrication of a cryogenic magnetocaloric composite by spark plasma sintering based on the RAl2 Laves phases (R= Ho, Er)

Abstract

We report the design and fabrication of a highly dense (>97%) two-phase magnetocaloric composite operating in the cryogenic temperature range based on the binary Laves phases HoAl2 and ErAl2 with a nearly table-like magnetic entropy change curve ΔSM(T) at 2 T. Such particular ΔSM(T) dependence was obtained, from the individual ΔSM(T) curves of the precursors, for the composition 28 wt% (ErAl2) + 72 wt% (HoAl2). This composition was selected to make a composite by spark plasma sintering from homogeneously mixed melt-spun ribbons of both intermetallic compounds. The calculated and experimental ΔSM(T) curves obtained for the as-sintered composite were found to be similar. Our results highlight the potential of this processing metallurgical technique for producing two-phase active magnetic regenerators with a designed entropy change curve for specific magnetic refrigeration applications.