Effects of crystallization treatment on the structure and magnetic properties of Gd65Fe25Zn10 alloy ribbons for magnetic refrigeration

Highlights: • Gd₆₅Fe₂₅Zn₁₀ alloys were prepared by melt-spinning followed by crystallization annealing. • T_C is close to room temperature for as-annealed Gd₆₅Fe₂₅Zn₁₀ alloys. • RC for Gd₆₅Fe₂₅Zn₁₀ as-annealed alloys is higher than that of Gd₅Si₂Ge₂ alloy. • Large (−ΔS_M)^max and negligible losses make the studied alloys suitable for magnetic refrigerant. The structure and magnetic properties of Gd₆₅Fe₂₅Zn₁₀ alloy ribbons prepared by melt-spinning followed by crystallization annealing were investigated. In the as-spun ribbons, there is a small amount of α-Gd nanocrystalline existed in the amorphous matrix. After crystallization treatment, besides the pre-precipitated α-Gd phase, GdFe₂ and GdZn crystalline phases precipitated in turn in the amorphous matrix. The Curie temperature (T_C) of the fully amorphous matrix is ∼250 K. Owing to α-Gd nanocrystalline precipitated in the amorphous matrix, a second order magnetic transition occurs near 288 K for both the as-spun and the as-annealed Gd₆₅Fe₂₅Zn₁₀ ribbons. For a field change of 2 T, the maximum magnetic entropy change (−ΔS_M)^max for the as-spun and as-annealed ribbons are 1.56–2.31 and 3.83–4.06 J/(kg·K), while the values of refrigeration capacity (RC_FWHM) are 224.0–387.0 and 149.5–158.0 J/kg, respectively. The as-spun Gd₆₅Fe₂₅Zn₁₀ ribbons display relatively low (−ΔS_M)^max but the largest RC_FWHM value due to the wide (−ΔS_M) versus T curve peak. With negligible thermal/magnetic hysteresis losses, relative large (‒ΔS_M)^max and its peak temperature near room temperature, the Gd₆₅Fe₂₅Zn₁₀ alloy ribbons can be used as the potential magnetic refrigeration material working at room temperature.