Magnetic Properties and Microstructural Modifications of Sm-Co-Hf Alloy Ribbons by B Addition

Microstructure optimization is highly desirable for improving the magnetic properties of permanent magnetic materials. To optimize the microstructure and hence the magnetic properties of Hf-added Sm-Co alloys, SmCo6.8Hf0.2Bx(x = 0-0.5) ribbons were fabricated by rapid solidification method and high intrinsic coercivity and low-temperature coefficients were obtained in SmCo6.8Hf0.2B0.4 alloy ribbons. HfB2 phase formed in the alloys which acted as grain boundary pinning center for improving the intrinsic coercivity. The grain boundary pinning enhanced greatly as a result of HfB2 phase formation, the initial magnetic susceptibility decreased, and an enhanced impediment effect is observed during magnetization process. SmCo6.8Hf0.2B0.4 alloy ribbons depicted best magnetic properties of intrinsic coercivity, H-cj = 1630 kA/m and remanence, J(r) = 0.52 T. The temperature coefficient of coercivity, beta = - 0.16%/degrees C was obtained in the temperature range of 27-400 degrees C, while an intrinsic coercivity of 497 kA/m at 500 degrees C showed the high-temperature stability of these alloys.

Automated summary

Microstructure optimization is crucial for improving the magnetic properties of permanent magnetic materials. In this study, Hf-added Sm-Co alloys were fabricated and it was found that the addition of Hf can optimize the microstructure and magnetic properties. Among the alloys, SmCo6.8Hf0.2B0.4 ribbon exhibited the best magnetic properties, with high coercivity and low temperature coefficient.