高丰度稀土永磁合金相平衡及微观组织与磁性能研究

结合广西稀土矿产资源优势，针对储量丰富的La、Ce、Y等高丰度稀土在永磁材料中的有效应用，推动稀土资源的平衡高值利用，本项目采用关键实验与热力学计算相结合的方法，测定高丰度稀土RE-Fe-B(RE=La, Ce, Y)合金的相平衡，确定高丰度稀土RE-Fe-B合金体系的相图热力学参数。采用扩散偶技术、电子探针微区成分分析及Boltzmann-Matano方法，测量高丰度稀土RE-Fe-B(RE=La, Ce, Y, Nd)合金中相关相的互扩散系数。利用获得的相图热力学参数和扩散动力学参数，计算多元高丰度稀土合金的稳定/亚稳相平衡信息以及合金中各相的成分随温度和时间的变化关系，设计制备高丰度稀土永磁合金样品，在实测合金样品的相结构、相转变、微观组织及内禀磁性能的基础上，探讨合金成分、微观组织结构与合金磁性能的相互作用关系，为研究开发高性能的高丰度稀土永磁材料提供实验数据和理论依据。

In this project, microstructure and magnetic properties of permanent alloys containing abundant rare elements (e.g. La, Ce, Y) are studied using thermodynamic calculation and diffusion kinetic modeling with the key alloy experiments. Phase equilibira of the RE-Fe-B(RE=La,Ce,Y) ternary systems including isothermal sections at different temperatures, vertical sections and liquidus projections are measured experimentally through key alloy experiments and diffusion couple technique. Thermodynamic parameters of all phases in the RE-Fe-B ternary systems are optimized based on the measured phase diagram data and thermodynamic information using the CALPHAD method and then thermodynamic database of the RE-Fe-B ternary systems are developed. On the other hand, using diffusion couple technique with electronic microprobe analysis (EMPA), interdiffusion coefficients of components in the RE-Fe-B(RE=La,Ce,Y,Nd) alloys were determined by means of the Boltzmann-Matano method. Through thermodynamic calculation and diffusion kinetic modeling using thermodynamic parameters and diffusion data, stable/metastable phase equilibira information on multi-component RE-Fe-B alloys and the relation of phase composition with temperature and time were obtained, which is fundamental to design and prepare novel Nd-Fe-B based permanent alloys containing abundant rare elements such as La, Ce and Y. Furthermore, structural transitions and intrinsic magnetic properties such as coercivity, remanent magnetization and maximum energy product of Nd-Fe-B alloys containing abundant rare elements are studied. Based on the thermodynamic calculation and diffusion kinetic modeling of the RE-Fe-B alloys, the relationships among the composition, crystal structure, phase transformation and magnetic properties of the alloys are elucidated, which is fundamental and of importance for developing novel Nd-Fe-B based permanent materials containing abundant rare elements.