Recent progress in high temperature permanent magnetic materials

Permanent magnetic materials capable of operating at high temperature up to 500°C have wide potential applications in fields such as aeronautics,space,and electronic cars.SmCo alloys are candidates for high temperature applications,since they have large magnetocrystalline anisotropy field(6–30 T),high Curie temperature(720–920°C),and large energy product([200 kJám-3)at room temperature.However,the highest service temperature of commercial 2:17type SmCo magnets is only 300°C,and many efforts have been devoted to develop novel high temperature permanent magnets.This review focuses on the development of three kinds of SmCo based magnets:2:17 type SmCo magnets,nanocrystalline SmCo magnets,and nanocomposite SmCo magnets.The oxidation protection,including alloying and surface modification,of high temperature permanent magnets is discussed as well.