Development of a material composition for effective room temperature magnetocaloric effect based on Fe-B-Zr precursor amorphous alloy

Abstract

We proposed a material composition based on Fe_81-xNb_xB₂Co₂Cr₅Zr₁₀ alloys to effectively balance the cooling efficiency and cost of consumption in magnetic refrigerators. Fe_81-xNb_xB₂Co₂Cr₅Zr₁₀ alloy ribbons were prepared by using a melt-spinning method and their magnetocaloric effect (MCE) was investigated through the measurements of magnetization. The Curie temperature (T_C) was successfully adjusted from 320 K (x = 0) to room temperature (298 K) with an Nb substitution (x = 2) to Fe. Besides a small hysteresis loss (coercive field about 0.005 T), its maximum magnetic entropy change (|ΔS_m|_max) was 1.0 J·kg⁻¹·K⁻¹ at 298 K under a magnetic field gradient (µ₀ΔH) of 1.2 T and deduced to be 2.8 J·kg⁻¹·K⁻¹ with a µ₀ΔH = 1.2 T. Moreover, this composition alloy exhibits a considerable refrigerant capacity (96.9 J·kg⁻¹) for µ₀ΔH = 1.2 T. The trade-off between the lowering T_C to room temperature, small hysteresis loss, and decline of |ΔS_m|_max can be attributed to the micro-alloyed composition with Nb. Due to these criteria characteristics for MCE materials, the Fe₇₉Nb₂B₂Co₂Cr₅Zr₁₀ composition alloy can be a potential material for magnetic refrigerant at room temperature.