A new Sm(Co,Fe,Cu)^sub 4^B/Sm^sub 2^(Co,Fe,Cu)^sub 7^ cell structure with the coercivity of up to 5.01?T

• Published in: Journal of magnetism and magnetic materials 2018-07, Vol.458, p.66
• Main Authors: Chi, Xiang, Li, Ying, Han, Xu-hao, Duan, Xiu-li, Sun, Ji-bing, Cui, Chun-xiang
• Format: Article
• Language: English
• Subjects: Alloys; Annealing; Cobalt; Coercivity; Fine structure; Grain boundaries; Intermetallic compounds; Iron; Magnetic anisotropy; Magnetic properties; Magnetism; Microstructure; Phase composition; Trace elements
• ISSN: 0304-8853; 1873-4766

A new Sm(Co,Fe,Cu)4B/Sm2(Co,Fe,Cu)7 cell structure is found, and its phase composition, microstructure and magnetic properties are investigated. Particularly, the atom structure of main phase is analyzed by extended X-ray absorption fine structure. It was found that as-spun SmCo2.94FeCu0.06B ribbons were composed of amorphous phase and approximate equiaxed Sm(Co,Fe,Cu)4B nanocrystallines. The high disorder of the nanocrystallines leads to the low magnetic anisotropy. After the as-spun ribbons were annealed at 800 °C for 30 min, the amorphous phase disappeared completely. The short rod-shaped Sm(Co,Fe,Cu)4B grains have a staggered distribution accompanied by ∼8 vol% lamellar Sm2(Co,Fe,Cu)7 phase at grain boundaries, and the new cell/cell-wall-type Sm(Co,Fe,Cu)4B/Sm2(Co,Fe,Cu)7 microstructure is produced. The annealed ribbons show an ultra-high coercivity of up to 5.01 T at room temperature, 40.64 T at 5 K (obtained by extrapolating), and estimated to be ∼ 41.96 T at 0 K. The microstructureal models of both ribbons are created and the coercivity mechanism is discussed in detail.