Glass forming ability and critical exponents in Hf-Modified Fe-Zr-B-Cu amorphous alloys for near room temperature magnetocaloric application

Abstract

Rare earth free magnetocaloric materials have emerged as a potential candidate for application in magnetic refrigeration presented in this work. A systematic investigation of Hafnium (Hf) substitution effects on the structural, thermal, magnetic, and magnetocaloric properties of rare earth free Fe-Zr-B-Cu alloys, synthesized via arc melting and melt spinning is reported in the present work. Comprehensive characterization using X-ray diffraction, differential scanning calorimetry, and vibrating sample magnetometry reveals enhanced magnetocaloric performance, with magnetic entropy change ≈ 1.856 J/kg K, 1.767 J/kg K, full-width at half-maximum () of 12.59 K, 31.98 K, and relative cooling power ≈ 23.36 J/kg, 56.50 J/kg under 2.5 T for Fe88Zr3Hf4B4Cu1,Fe88Zr1Hf6B4Cu1 alloys respectively. The analysis of critical exponents substantiates the occurrence of a second-order phase transition from paramagnetic to ferromagnetic at = 293 K for Fe88Zr3Hf4B4Cu1 alloys and = 303 for Fe88Zr1Hf6B4Cu1 alloys, in accordance with the mean-field model and the Widom scaling relation. These findings demonstrate the potential of Hf substitution in optimizing magnetocaloric properties and elucidating critical behavior, paving the way for advanced magnetic refrigeration materials.