定向凝固NdFeB永磁合金中包晶相的取向生长研究

发布时间：2019-03-17 15:11

【摘要】：选取NdFeB稀土永磁合金作为研究对象,采用Bridgman定向凝固工艺,将Bitter粉纹磁畴图像与X射线衍射分析方法相结合,系统研究定向凝固过程中金属间化合物包晶相Nd2Fe14B(T1相)的生长形态及取向变化规律。研究表明:定向凝固过程中包晶T1相的形态及择优生长方向与合金成分及凝固速率有关。凝固速率较低时(小于10μm·s-1),包晶T1相以典型的小平面方式生长,表现出强的晶体学特性。随着凝固速率增大,T1相晶粒逐渐细化,T1相生长界面出现粗糙化趋势;Nd11.76Fe82.36B5.88合金在1μm·s-1凝固速率下,T1相的易磁化轴[001]方向几乎沿热流方向,这与T1相沿a轴[100]方向择优生长的传统解释有很大不同;Nd13.5Fe79.75B6.75合金中T1相的轴向择优取向随凝固速率的增加逐渐偏离c轴而转向a轴,其原因可能是凝固速率的增加引起T1相沿[100]和[001]方向的生长驱动力即生长速率的改变。
[Abstract]:The NdFeB rare earth permanent magnet alloy was selected as the research object. Bridgman directional solidification process was used to combine the Bitter powder grain domain image with X-ray diffraction analysis method. The growth morphology and orientation of intermetallics peritectic phase Nd2Fe14B (T1 phase) during directional solidification were studied systematically. The results show that the morphology and preferred growth direction of peritectic T1 phase during directional solidification are related to the composition and solidification rate of the alloy. When the solidification rate is low (less than 10 渭 m 路s-1), the peritectic T1 phase grows in a typical small plane mode, showing strong crystallographic characteristics. With the increase of solidification rate, the grain size of T1 phase becomes finer gradually, and the growth interface of T1 phase tends to be roughened. At the solidification rate of 1 渭 m 路s-1, the easy magnetization axis [001] of T1 phase almost follows the direction of heat flow, which is quite different from the traditional explanation of preferred growth of T1 phase along a axis. The axial preferred orientation of T1 phase in Nd13.5Fe79.75B6.75 alloy gradually deviates from c axis and turns to a axis with the increase of solidification rate. The reason may be that the growth driving force of T1 phase along the directions of [100] and [001] is changed due to the increase of solidification rate.
【作者单位】：西安科技大学材料科学与工程学院;西北工业大学凝固技术国家重点实验室;
【基金】：国家自然科学基金项目(51201130) 西安科技大学博士启动基金项目(2012QDJ015)资助
【分类号】：TG132.27

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