Enhancement of the magnetic refrigerant capacity in partially amorphous Fe70Zr30 powders obtained by mechanical alloying

After mechanical alloying Fe70Zr30 composition from pure starting powders, an amorphous phase with Curie temperature TC = 244 K and an intermetallic compound (that should be non-stoichiometric Zr-rich fcc Fe2Zr phase) with TC = 355 K are formed. Residual α-Fe crystallites are also found. The multiphase character of this system yields a non-monotonic dependence of the magnetocaloric effect (characterized by the refrigerant capacity, RC) on the fraction of phases. Among the samples studied in this work, RC is enhanced for samples with the highest fraction of intermetallic compound, although the maximum magnetic entropy change monotonically decreases with the increase of the fraction of this phase. This behaviour agrees with the predicted one for biphasic systems.