Development of Anisotropic Misch-Metal-Fe-B Melt-Spun Magnets and its Application to Plastic Magnets

人们已经认识到，开发混合稀土在电工材料中的应用领域对于有效地消耗自然资源具有重要意义。我们研制出了能量积大于8 MGOe的MM-Fe-B各向同性快淬磁体。其成本性能（以单位能量产品成本衡量）与钡铁氧体磁体相当。在本研究计划中，努力开发c轴取向技术，以获得更高的性价比永磁体。(1)在熔体淬火工艺的各种参数中，熔体喷射到旋转轮上时的温度是影响R2 Fe 14 B四元化合物c轴取向的最重要的参数。当温度保持在熔点以上200度时，在自由表面和轮表面上都可以获得3度分散范围内的大多数完美的c轴取向。(2)取向层厚度在自由表面为15 μ m，在砂轮表面为5 μ m。中间层具有较少取向的结构。(3)添加第四元素如Ta和Zr改善了c轴取向。前者和前者的元素是有效的定向在自由和轮表面，分别。(4)伴随着c轴取向，晶粒尺寸趋于粗化。为了获得高的结晶度，控制材料在晶界处的沉淀是必要的。

It has been recognized that development of application field of misch metal (MM) to electrical materials is of great importance with respect to effective consumption of natural resources. We developed the MM-Fe-B isotropic melt-spun magnets with the energy product more than 8MGOe. Its cost-performance (measured with cost per energy product) is comparable to that of Ba ferrite magnets. In this research program, effort was made to develop the c-axis orientation technique for higher cost-performance permanent magnets.(1) Among various parameters of melt-quenching technique, the temperature of the melt when ejected onto the rotating wheel is the most important one affecting the c-axis orientation of the R2Fe14B tetragonal compounds. When the temperature is kept 200 degree higher than the melting point, mostly perfect c-axis orientation within 3 degree dispersion was available on both the free and wheel surfaces.(2) The thickness of orientated layer is 15 mu m on the free surface and 5 mu m on the wheel surface. The intermediate layer has the less oriented structure.(3) Addition of fourth elements such as Ta and Zr improve the c-axis orientation. The former and former elements are effective on the orientation at free and wheel surfaces, respectively.(4) Accompanied by the c-axis orientation, grain size tends to be coarse. To obtain the high coercivity, control of the materials precipitaing at the grain boundary seems necessary.