Magnetocaloric effect of Fe-RE-B-Nb (REÂ =Â Tb, Ho or Tm) bulk metallic glasses with high glass-forming ability

The magnetocaloric effect of (Fe0.71RE0.05B0.24)96Nb4 (RE = Tb, Ho and Tm) bulk metallic glasses (BMGs) of diameters up to 6.5 mm were attained by 4.8 at.% RE alloying. The Curie temperature (TC) of Tm doped alloy, being the highest among these alloys, deviates from typical relationship between TC and de Gennes factor. Its unique electronic structure has been suggested to attribute to the observed trend. Furthermore, Tm doped alloy presents the largest peak magnetic entropy change (|ΔSMpk|) of 1.21 J kg−1 K−1 for an applied field of 1.5 T, which compares favorably with those of other Nanoperm-type alloys. The phenomenological universal curve for ΔSM demonstrates that alloys exhibit similar critical exponents at TC. This family of heavy RE doped Fe-based BMGs is potential candidate used as bulk magnetic refrigerants with the final required shapes.