混合合金法添加Ga对Nd—Dy—Fe—Co—B烧结磁体的磁性和微观结构的影响

对用混合合金法制备的Nd7.69Dy6.62Fe64.33Co14.83B6.53/Ga烧结磁体的磁性和微观结构进行了研究。结果表明：添加0.5%（质量分数）的Ga后；磁体的iHc由1232kA/m升高到1819kA/m，在200℃放置0.5h后的磁通不可逆损失由33.3%下降到5%以下，当Ga的添加量达到1.0%左右时，Ga的作用达到最大值，微观结构分析表明，不添加Ga磁体的晶粒边界，尤其是晶界角隅处多呈现弯曲和凹凸不平的形状，添加Ga磁体的晶粒边界则呈现平滑和近似直线的形状，烧结过程中Ga原子置换Nd2Fe14B相中Fe原子形成Nd2Fe14-xGaxB相，与此同时，被置换的Fe原子进入液相与富和Nd相、富B相反应形成新的Nd2Fe14B（或Nd2Fe14-xGaxB）相，这是导致磁体的磁性和微观结构发生变化的主要原因。

EFFECT OF Ga ADDITION ON THE MAGNETIC PROPERTIES AND MICROSTRUCTURE OF Nd-Dy-Fe-Co-B SINTERED MAGNET PREPARED BY BLENDING METHOD

The effect of gallium added by blending method on the magnetic properties, thermal stabilities and microstructures of Nd769Dy6.62Fe64.33Coi4.83B6.53 sintered magnets was investigated. The experimental results show that, by adding 0.5 (mass fraction, %)Ga, the i H c is increased from 1232 to 1819 kA/m and the irreversible loss of open flux after exposed at 200 ~C for 0.5 h is reduced from above 33% to below 5%. The addition of proper amount Ga can also enhance (BH)max because of the formation of newborn Nd2Fe14-xGaxB hard phases. Microstructure analysis indicates that the grain boundaries of Ga-free Nd-Fe-B magnets appear to be uneven. On the other hand, the boundaries of Ga-containing magnets appear preferentially in straight and smooth shape.