Effect of Cu Substitution and Heat Treatment on Phase Formation and Magnetic Properties of Sm12Co88-xCux Melt-Spun Ribbons

The phase structure and microstructure of Sm12Co88-xCux (x = 0, 2, 4, 6, 8, 10; at.%) as-cast alloys and melt-spun ribbons prepared via the arc-melting method and melt-spun technology were studied experimentally by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The results reveal that the Sm12Co88-xCux (x = 0) as-cast alloy contains Sm2Co17 and Sm5Co19 phases, while the Sm12Co88-xCux (x = 2) as-cast alloy is composed of Sm2Co17, Sm2Co7 and Sm(Co, Cu)(5) phases. Sm2Co17 and Sm(Co, Cu)(5) phases are detected in Sm12Co88-xCux (x = 4, 6, 8, 10) as-cast alloys. Meanwhile, Sm12Co88-xCux ribbons show a single SmCo7 phase, which is still formed in the ribbons annealed at 1023 K for one hour. After annealed at 1123 K for two hours, cooled slowly down to 673 K at 0.5 K/min and then kept for four hours, the ribbons are composed of Sm2Co17 and Sm(Co, Cu)(5) phases. The magnetic measurements of Sm12Co88-xCux ribbons were performed by vibrating sample magnetometer (VSM). The results exhibit that the maximum magnetic energy product ((BH)(max)), the coercivity (H-cj) and the remanence (B-r) of the Sm12Co88-xCux ribbons increase generally with the increase in Cu substitution. In particular, the magnetic properties of the ribbons annealed at 1123 K and 673 K increase significantly with the increase in Cu substitution, resulting from the increase in the volume fraction of the formed Sm(Co, Cu)(5) phase after heat treatment.

Automated summary

The phase structure and microstructure of Sm12Co88-xCux alloys and ribbons were studied experimentally, and the results showed that the Cu substitution had a significant effect on the phase composition and crystal structure of the alloys. Magnetic measurements indicated that the magnetic properties of the ribbons were improved with the increase in Cu substitution.