Microstructure and magnetocaloric properties of partially crystallized Gd 60 Co 30 Fe 10 amorphous alloy prepared by different solidification cooling rates

The Gd 60 Co 30 Fe 10 alloy ribbons with different solidification cooling rates were prepared by modifying the melt-spinning speed of 6.0, 12.5, 25.0 and 50.0 m·s −1 . With cooling rate decreasing, the (Fe,Co) 5 Gd and hcp-Gd nanocrystalline was in situ precipitated among the amorphous matrix, which resulted in the composition change of the amorphous phase. Because of the only slight amount of crystalline phase in Gd 60 Co 30 Fe 10 alloys, the magnetic and magnetocaloric properties mainly depend on the amorphous phase, and all the magnetic entropy change versus temperature (|Δ S M |– T ) curves are table-like, indicating the suitability for Ericsson cycle. The magnetic transition temperature of the Gd 60 Co 30 Fe 10 alloy at a melt-spinning speed of 6.0 m·s −1 shifted obviously to the lower value with the applied magnetic fields increasing. The peak value of magnetic entropy change (|Δ S M pk |) is 2.19 J·kg −1 ·K −1 at 217 K under the magnetic field change of 0–2 T, and the table-like region is 200–230 K. It was proved that the moderate reduction of the cooling rate will not deteriorate the magnetocaloric performance of the Gd 60 Co 30 Fe 10 ribbons seriously. 摘要 使用熔体旋淬法, 通过调节辊轮转速为6.0, 12.5, 25.0 和 50.0 m·s −1 , 制备了不同冷却速度的Gd 60 Co 30 Fe 10 合金条带。随着冷却速度的降低, (Fe,Co) 5 Gd和hcp-Gd纳米晶从非晶基体中原位析出, 使非晶相的成分发生变化。由于析出的晶相含量较低, 因此整个样品的磁性能和磁热性能主要取决于非晶相, 磁熵变温变 (|Δ S M |-T) 曲线均呈平台型, 表明其适用于Ericsson循环。辊轮转速为6.0 m·s −1 时制备的Gd 60 Co 30 Fe 10 合金的磁转变温度随着外加磁场的增加明显向低温偏移, 在磁场变化为0-2 T的条件下, 217 K时磁熵变峰值 (|Δ S M pk |) 为2.19 J·kg −1 ·K −1 , 平台区为200-230 K。本研究证明适度的降低冷却速度, 不会使Gd 60 Co 30 Fe 10 合金条带的磁热性能表现严重恶化。