Effect of current annealing treatment on magnetic properties of Gd-Al-Co-Fe metallic microfibers

• Published in: Journal of alloys and compounds 2021-02, Vol.855, p.157231, Article 157231
• Main Authors: Liu, Jingshun, Huang, Meifang, Wu, Mengjun, Zhang, Yun, Cao, Guanyu, Li, Ze, Chen, Hongneng, Yu, Tianchi, Wang, Xufeng, Liu, Rui, Qu, Guanda, Pang, Mengyao, Shen, Hongxian
• Format: Article
• Language: English
• Subjects: Aluminum; Annealing; Annealing current intensities; Cobalt; Curie temperature; Gadolinium; Gd-Al-Co-Fe metallic Microfibers; Iron; Low temperature; Magnetic anisotropy; Magnetic properties; Magnetocaloric effect (MCE); Maximum magnetic entropy change (ΔSmmax); Microfibers; Nanocrystals; Refrigerant capacity (RC); Refrigerants; Refrigeration; Residual stress
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.157231

Herein, the influence of annealing current intensities on magnetic properties of Gd-based microfibers was systematically investigated. The experimental results indicated that the as-prepared microfibers have amorphous structure and excellent thermal-stability, and the Curie temperature TC of which slightly change before and after annealing. The general magnetic physical magnitudes (Ms, Mr, μ0Hc and μm) of microfibers increase firstly and then decrease with the rising of annealing current intensities, and those of the microfibers annealed at 90 mA microfibers are more obvious (Ms = 255 A m2/kg and μm = 0.38 ± 0.01). Similarly, the magnetocaloric parameters of microfibers also increase firstly and then decrease with the rising of current intensities. At 5 T of magnetic field change μ0ΔH, the maximum magnetic entropy change ΔSmmax and refrigerant capacity RC of 90 mA annealed metallic microfibers are 12.77 J/(kg·K) and 906 J/kg, respectively, and which remarkably increased in compared with the as-prepared state, respectively. From the microstructural evolution perspective, a certain intensity current annealing induces the tendency of micro-regional clusters and nanocrystals, forming atomic ordered regions, and the internal residual stress release with a reduction of magnetic anisotropy. Meanwhile, the magnetic ordering and the critical magnetic-moment rotational driving-force were changed after Fe-doping, resulting in effective improvement of refrigerant capacity. Accordingly, the current-annealed Gd-Al-Co-Fe microfibers can be adopted as low-temperature magnetic refrigeration working-medium, which also provides a theoretical foundation for magnetic refrigeration technology application. Magnetocaloric properties of Gd-Al-Co-Fe metallic microfibers current-annealed at 90 mA are significantly improved according to the microstructural evolution and magnetic ordering modulation. [Display omitted] •Effects of current annealing intensities on the magnetic properties were investigated in detail.•MCE characteristics of Gd-Al-Co-Fe microfibers could be obviously improved at 90 mA.•Magnetocaloric mechanism is illustrated by the perspective of structural evolution and magnetic ordering transformation.