Cause of the Failure of Sintered Blanks of Ring Nd–Dy–Fe–Co–B Magnets with a Radial Texture

—The problem of destruction of blanks of ring Nd–Dy–Fe–Co–B magnets with a radial texture and different cobalt and dysprosium contents is considered. The cause of the failure of radial rings after sintering consists in the presence of the (Nd, Dy)(Fe,Co) 4 B phase, which is characterized by a high linear thermal expansion coefficient. It is shown that the contribution of the (Nd, Dy)(Fe, Co) 4 B phase to the saturation magnetization can be neglected. The identified phase is found to have a compensation temperature of 100 K.