Research on high‐performance NdFeB magnets

Abstract

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 Nd2Fe14B, Nd1.1Fe4B4 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 Nd2Fe14B and the Nd1.1Fe4B4 phase. The residual flux density (Br) of Nd‐Fe‐B magnets increases in proportion to the increase in the among of the Nd2Fe14B phase. By contrast, the intrinsic coercivity (iHc) declined because of a decrease in the amount of the Nd1.1Fe4B4 and the Nd‐rich phase. As a result, new high‐performance Nd‐Fe‐B magnets with the maximum energy product of above 366 kJ/m3 (46 mgOe) have been developed by means of controlling the component ratios of these phases in Nd‐Fe‐B magnets.