钕铁硼永磁合金烧结过程中的晶粒聚集长大及对磁性能的影响

The Grain Aggregation and Growth and its Effect on the Magnet Property of the Nd-Fe-B Permanent Alloy in the Sintering

研究了钕铁硼永磁合金烧结过程中的晶粒聚集长大现象。结果表明:合金粉末在强磁场下成型时的取向导致磁体烧结时形成织构,那些较早结合的、晶粒位向非常一致的、晶界上无第二相的晶粒合并形成尺寸较大的晶粒吞食周围的小晶粒,形成异常粗大的晶粒,即发生了晶粒的聚集长大,晶粒的聚集长大导致矫顽力的明显降低,对取向度略有改善,因而剩余磁感应强度稍有提高,但最大磁能积降低。低钕、低氧含量、富钕相分布不均匀的钕铁硼永磁合金在较高温度下烧结时容易发生晶粒的聚集长大。

The grain aggregation and growth of Nd-Fe-B permanent magnet alloy in the sintering are studied, it turns out when its shaping, the orientation of the alloy powder in the powerful magnetic field results in the texture in the sintering. Those grains that combine earlier and have almost the same orientation combine to bigger grains. They eat the smaller grains around, forming the preternatural big grains. This makes an apparent decrease of the coercive force, and also gives a modification to the orientation. So the remained magnetic induction intensity is improved slightly, but the maximum magnetic energy product decreases. The aggregation and growth of grains in the Nd-Fe-B permanent magnet alloy with the lower Nd, lower oxygen, and the uneven distribution of rich Nd happen easily in higher temperature.