Research on high‐performance NdFeB magnets

The effects of the constituent phase of Nd‐Fe‐B magnets on sintering behavior are investigated. In the case of Nd‐Fe‐B magnets, a liquid phase forms by ternary eutectic reaction of Nd 2 Fe 14 B, Nd 1.1 Fe 4 B 4 and Nd‐rich phase at 938 K. When the sintering temperature is raised above 1273 K, a remarkable shrinking occurs because of an increase in the amount of liquid phase which is supplied by the reaction between the Nd 2 Fe 14 B and the Nd 1.1 Fe 4 B 4 phase. The residual flux density ( B r ) of Nd‐Fe‐B magnets increases in proportion to the increase in the among of the Nd 2 Fe 14 B phase. By contrast, the intrinsic coercivity ( i H c ) declined because of a decrease in the amount of the Nd 1.1 Fe 4 B 4 and the Nd‐rich phase. As a result, new high‐performance Nd‐Fe‐B magnets with the maximum energy product of above 366 kJ/m 3 (46 mgOe) have been developed by means of controlling the component ratios of these phases in Nd‐Fe‐B magnets.