Magnetic Properties and Phase Transformation of Sm-Fe-Co-X (X = Ga, V, B, Si, and Ti) Permanent Magnetic Materials

The magnetic properties and phase transformation of Sm(Fe0.8Co0.2)11X (X = Ga, V, B, Si, and Ti) were investigated. The Sm(Fe0.8Co0.2)11X ribbons were produced by rapid solidification process, and their phase transformation and magnetic properties were analyzed using DSC and VSM. It was confirmed that the melt-spun amorphous phase was converted to the ɑ-Fe phase, then to TbCu7-type phases, and finally to the ThMn12-type phase. Magnetic property measurements show that the coercivities of the Sm(Fe0.8Co0.2)11X ribbons vary with the compositions. The Ti substituted sample has the highest concentration of ThMn12-type phase across all annealing temperatures and the corresponding coercivity is also the highest among the samples. The squareness, Mr/Ms, of the samples shows that the trends follow the degree of crystallinity of the ThMn12-type phase, so that higher concentrations of hard magnetic phase result in the enhanced squareness.