Effect of isothermal aging process on the microstructure of grain boundary regions in Sm(Co, Fe, Cu, Zr)z magnets

2:17-type SmCo permanent magnets have been widely applied in applications under elevated temperature due to their good magnetic properties and excellent thermal stability [1]- [5]. It is confirmed that complete cellular nanostructure in grain boundary regions is very important for improving the magnetic properties of the magnets. In this study, the effect of isothermal aging process on the microstructure of grain boundary regions is systematically investigated. As the isothermal aging duration increases from 30 to 720 minutes, the number of 1:5H cell boundary phase in grain boundary regions is reduced, which leads to incomplete cellular nanostructure. However, the grain size is getting increase, results in the decrease of grain boundaries, which has a positive effect on the squareness. Meanwhile, the coercivity is enhanced with the isothermal aging duration increase. The above findings deepen our understanding of the correlation between isothermal aging process and cellular nanostructure of grain boundary regions, and is beneficial to provide potential considerations for the preparation of high performance magnets.