Enhancement of local anti-demagnetization ability of permanent magnet by selected area grain boundary diffusion toward high-speed motors

The working environment of permanent magnets in high-speed motors is harsh, because they are seriously affected by multi-physical fields such as temperature, stress, weak magnetic control field, etc., and irreversible demagnetization is easy to occur under the extreme working conditions. In this work, a model of high-speed Interior Permanent magnet Motor is established, the easy demagnetization area of the permanent magnet is simulated by electromagnetic and thermal simulations to determine, and its local anti-demagnetization optimization is performed. Dy/Tb co-infiltration is carried out in the easy demagnetization region of the permanent magnets, and the process of selective zone diffusion is analyzed based on the principle of selective zone grain boundary diffusion. Through microscopic observation and macroscopic magnetic performance test, the effect of local anti-demagnetization performance enhancement of the optimized permanent magnets is verified. The results show that the magnetic properties of the optimized permanent magnets are obviously improved after the optimization of the selected zones. The present approach is important for the follow-up less heavy-rare-earth research of permanent magnet and its application in high-speed motors.