(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 研究一级时效、两级时效和多级时效处理对Sm(CoFe0.20Cu0.12Zr0.03)7.5磁性能的影响，并引入扩散长度探讨材料时效处理动力学机制。结果表明，一级时效处理的温度越高，材料的扩散系数DT1越大，达到某一特定扩散长度所需的时间越少，即磁体达到矫顽力峰值所需的时间越短。在连续降温处理过程中，达到某一特定扩散长度所需的时间与降温幅度和扩散系数有关，Cu原子的扩散长度是连续降温时效处理过程的主要影响因素。Sm2Co17型永磁材料的典型显微结构是由2׃17R主相和1׃5胞壁相所组成的胞状结构以及片状结构构成。当一级时效温度T1和二级时效温度T2固定时，达到特定扩散长度所须的时间与这2个温度下磁体的扩散系数成反比。Cu原子沿片状相的扩散速率比沿晶内体扩散速率大，当磁体内片状相含量较多时，Cu原子的扩散系数可大大增加，可有效缩短扩散所需时间。
关键字: 稀土永磁；时效处理；胞状结构；扩散长度
（State Key Laboratory of Powder Metallurgy, Central South University,Changsha 410083, China）
Abstract:The magnetic properties and one-step aging, two-step aging and multilevel aging treatment of Sm(CoFe0.20Cu0.12Zr0.03)7.5 were investigated, and the kinetic mechanism was analysed by inducing diffusion length. The results show that the higher the first step aging temperature, the larger the diffusion coefficient DT1 and the shorter the time necessary to achieve a certain diffusion length, which implies the shorter the time to reach the coercivity peak value. During the continuous cooling treatments, the time necessary to achieve a certain diffusion length is related to the temperature decreasing rate and diffusion coefficient, and the diffusion length of Cu is the main factor, respectively. The microstructure of Sm2Co17-based rare-earth permanent magnets consists of 2׃17R main phase, 1׃5 cell boundary phase and lameller phase. When the aging temperature T1 and T2 are fixed, the time necessary to achieve a certain diffusion length is inverse-proportional to the diffusion coefficient. Because the diffusion rate of Cu in the lameller phases is larger than that in the grains, the diffusion coefficient of Cu can be increased with increasing the content of lameller phase, and the diffusion time can be shortened effectively.
Key words: rare-earth permanent magnets; aging treatment; cellular structure; diffusion length
