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

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 [Formula: see text] ≈ 1.856 J/kg K, 1.767 J/kg K, full-width at half-maximum ([Formula: see text]) of 12.59 K, 31.98 K, and relative cooling power [Formula: see text] ≈ 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 [Formula: see text] = 293 K for Fe₈₈Zr₃Hf₄B₄Cu₁ alloys and [Formula: see text] = 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.