Effect of Cu Substitution and Heat Treatment on Phase Formation and Magnetic Properties of Sm(12)Co(88−x)Cu(x) Melt-Spun Ribbons

The phase structure and microstructure of Sm(12)Co(88−x)Cu(x) (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 Sm(12)Co(88−x)Cu(x) (x = 0) as-cast alloy contains Sm(2)Co(17) and Sm(5)Co(19) phases, while the Sm(12)Co(88−x)Cu(x) (x = 2) as-cast alloy is composed of Sm(2)Co(17), Sm(2)Co(7) and Sm(Co, Cu)(5) phases. Sm(2)Co(17) and Sm(Co, Cu)(5) phases are detected in Sm(12)Co(88−x)Cu(x) (x = 4, 6, 8, 10) as-cast alloys. Meanwhile, Sm(12)Co(88−x)Cu(x) ribbons show a single SmCo(7) 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 Sm(2)Co(17) and Sm(Co, Cu)(5) phases. The magnetic measurements of Sm(12)Co(88−x)Cu(x) 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 Sm(12)Co(88−x)Cu(x) 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.