Influence of Fe substitution on thermal stability and magnetocaloric effect of Gd60Co40-x Fe x amorphous alloy

Highlights: • The Fe replacement is adverse to thermal stability of Gd₆₀Co_40-xFe_x glassy alloy. • Table-like magnetocaloric effect was obtained in alloys with x = 10, 15 and 20. • Above phenomenon is due to local structural inhomogeneity in the amorphous matrix. • The power law and universal behavior of magnetic entropy change were constructed. A series of Gd₆₀Co_40-xFe_x (x = 0, 5, 10, 15, 20) amorphous ribbons were synthesized by melt-spinning method, and the addition of Fe is detrimental for thermal stability as well as glass forming ability of the alloys. With the increasement of Fe content, the magnetic transition temperature increases firstly and then decreases with the peak of 239 K obtained in Gd₆₀Co₃₀Fe₁₀, while the magnetic entropy change |ΔS_M| reduces gradually. This phenomenon is possibly caused by variation of predominant exchange interaction from ferromagnetic to ferrimagnetic. Among these alloys, Gd₆₀Co₃₀Fe₁₀, Gd₆₀Co₂₅Fe₁₅ and Gd₆₀Co₂₀Fe₂₀ represent table-like magnetocaloric effect of 4.4 ± 0.1 Jkg⁻¹K⁻¹, 4.0 ± 0.1 Jkg⁻¹K⁻¹ and 3.8 ± 0.1 Jkg⁻¹K⁻¹ in wide temperature ranges of 201–238 K, 178–228 K and 178–218 K under an applied field H of 5 T, which is probably ascribed to the local structural inhomogeneity in the amorphous matrix. This hypothesis could be confirmed by the deviation of exponent n (|ΔS_M| ∝ Hⁿ) and the universal behavior of |ΔS_M|-T curves. The present study is expected to enhance the knowledge about the influence of additional elements on magnetocaloric effect and improve the performance of amorphous refrigerants in the Ericsson-cycle near room temperature.