Unraveling the mechanical anisotropy in Sm2Co17-type permanent magnets

Under high-impact or vibration conditions, Sm 2 Co 17 -type permanent magnets exhibit pronounced mechanical anisotropy and a tendency to fracture, which severely compromises their service life and operational reliability. To probe this behavior, rectangular samples were wire-cut from the same magnet. One group of samples had their long sides aligned parallel to the c -axis, while the other group was oriented perpendicular to it. Fracture analysis revealed that the surface parallel to the c -axis exhibited more river-like patterns and cleavage steps. Vickers indentation test further showed that the average length of major cracks on this surface was shorter, and more micro-cracks formed at the indentation edges. Significant anisotropy was observed in the grain size, the number of low-angle grain boundaries (LAGBs), and the formation of shear bands on the surfaces perpendicular and parallel to the c -axis. Specifically, the surface parallel to the c -axis displayed smaller grain size, a higher density of LAGBs, and a greater propensity to form shear bands under applied load. These microstructural features contributed to enhanced flexural strength and improved deformation capability. This study provides important insights into the microstructural deformation mechanisms underlying the mechanical anisotropy of Sm 2 Co 17 -type permanent magnets.