高磁能积2:17型钐钴永磁材料的新进展

The 2:17-type Sm-Co-Fe-Cu-Zr magnets are the strongest high temperature permanent magnets, which have been found wide applications in high-technologies and national defense. Early invesitgations have shown that raising Fe content can allow magnets obtain higher theoretical energy product. Therefore, the development of Fe-rich magnets with higher maximum energy product can not only facilitate the utilizations in more miniaturized magnet-associated devices, but also significantly reduce the production cost, which has been one of the important directions in the field of Sm-Co-based permanent magnets. In this work, based on the magnetic performance bottleneck for fabricating high energy product Sm-Co-based magnets, we briefly summarize the recent research advances of the Fe-rich magnets. Focusing on the origin that it is difficult to form complete nanocellular structure in Fe-rich magnets, new approaches have been developed to enhance their magnetic properties, including the new powder fabrication technologies such as hydrogen crushing and jet milling, the new heat-treating procedures including intermediate heat treatment, pre-aging, and multi-stage aging treatment, and the dual-alloy technology to opitimze the cellular nanostructure. With these new technoclogies, the obtained maximum energy product has exceeded 35 MGOe. High-performance sintered magnets with maximum energy product above 30 MGOe and coercivity above 30 kOe have also been successfully developed in China. Based on these advances, the fundamental issues to be solved to develop magnets with higher magnetic performance are also suggested.