Evidence for domain wall pinning by a magnetic grain‐boundary phase in sintered Nd‐Fe‐B based permanent magnets

Low‐field thermomagnetic analysis of sintered Nd(Dy)‐Fe(Co)‐B magnets provides new evidence that the high coercivity near room temperature is due to the pinning of residual domain walls in a ferromagnetic grain‐boundary phase. The temperature where MHc drops to near zero appears to be the Curie point of that phase. It is 50–80 °C below the Tc of the 2‐14‐1 matrix.