Nd-Fe-B系磁石の高性能化

抄録

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, Nd_1.1Fe₄B₄ and Nd-rich phase at 938K. When sintering temperature is raised above 1, 273K, a remarkable shrinking occures because of an increase in the amount of a liquid phase which is supplied by a reaction between Nd₂Fe₁₄B and Nd_1.1Fe₄B₄ phase. The residual flux density (B_r) of Nd-Fe-B magnets increases in proportion to the increase in the amount of the Nd₂Fe₁₄B phase. On the contrary, the intrinsic coercivity (_iH_c) declined because of a decrease in the amount of the Nd_1.1 Fe₄B₄ and the Nd-rich phase. As a result, new high-performance Nd-Fe-B magnets having the maximum energy product of above 366kJ/m³ (46 MGOe) has been developed by means of controlling the component ratios of these phases in Nd-Fe-B magnets.