稀土Sm-Co基永磁合金相图及微观组织与磁性能构效关系研究

针对储量丰富的Ce、Y等高丰度稀土在稀土高温Sm-Co永磁材料中的有效应用，推动稀土资源的平衡高值利用，本项目采用关键合金和扩散偶实验与相图热力学计算、扩散动力学模拟相结合的方法，确定稀土RE-Co-Fe/Cu/Zr（RE=Sm, Ce, Y）合金体系的相图以及体系中各相的扩散系数和原子移动性参数，建立Sm-Co基合金体系相图热力学数据库和扩散动力学数据库。基于所构建的相图热力学数据库和扩散动力学数据库，利用相场模拟计算，研究高丰度稀土及过渡族金属对稀土Sm-Co基永磁合金时效析出的胞内主相与胞壁强化相原子的分布情况及胞状组织微观结构变化的影响规律。在此基础上，优化设计多元稀土Sm-Co基永磁合金样品，实测合金的相结构、相转变、微观组织以及内禀磁性能，探讨合金微观组织结构变化与磁性能的构效关系，为研究开发高温稀土永磁材料提供实验数据和理论依据。

Sm-Co-based permanent magnets with better temperature stability and corrosion resistance as well as superior magnetic properties have been used widely in the industrial applications. In this project, the microstructure and magnetic properties of Sm-Co-based permanent alloys containing abundant light rare elements (e.g. Ce, Y) and transition metals (e.g. Fe, Cu, Zr) are studied using thermodynamic and calculation, diffusion kinetic modeling and phase field method with the key experiments. Phase equilibira of the RE-Co-Cu/Fe/Zr (RE=Sm,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-Co-Cu/Fe/Zr (RE=Sm,Ce,Y) ternary systems are optimized based on the measured phase diagram data and thermodynamic information using the CALPHAD method and then thermodynamic database of the the RE-Co-Cu/Fe/Zr (RE=Sm,Ce,Y) ternary systems are developed. On the other hand, using diffusion couple technique with electronic microprobe analysis, interdiffusion coefficients of components in the Sm-Co-based 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 of multi-component Sm-Co-based alloys and the relation of phase composition with temperature and time were obtained, which is significant to design the compositions of Sm-Co-based permanent alloys. Furthermore, intrinsic magnetic properties (e.g. coercivity, remanent magnetization and maximum energy product) of Sm-Co-based alloys are studied. Based on thermodynamic and diffusion kinetic calculations and phase field modeling of Sm-Co-based alloys, the relationships among the composition, phase transformation, microstructure and magnetic properties of the alloys are elucidated, which is fundamental and of importance for developing novel Sm-Co-based high temperature permanent magnets.