单相铸锭制得高剩磁Sm_2Co_(17)基永磁合金磁性能和微观结构

The magnetic properties and microstructure of Sm_2Co_(17)-type sintered permanent magnetic alloy with high remanence made of single-phase ingot

研究了用均质化处理后铸锭制成的名义成分为Sm(CobalFe0.245Cu0.07Zr0.02)7.8(原子分数%)的Sm_2Co_(17)基烧结永磁合金不同等温退火热处理温度Tia(785,800,815,830℃)的磁性能和微观结构。结果显示,随着Tia从785℃增加到830℃,磁体的剩磁Br(～1.157T)基本保持不变,内禀矫顽力Hcj呈现出先增大后减小的变化规律。TEM观察结果显示等温退火热处理温度分别为785℃和815℃时的终态磁体的微观结构有如下区别:胞状微结构的平均尺寸不同,785℃的终态磁体的胞状微结构的平均尺寸约115nm,而815℃的终态磁体的胞状微结构的平均尺寸约82nm;另外,1∶5H胞壁相所占的体积分数不同,785℃的终态磁体中1∶5H胞壁相所占的体积分数明显小于815℃的终态磁体中的。这是内禀矫顽力Hcj在815℃时达到极大值的两个主要原因。

The magnetic properties and microstructures of Sm2Co17-based sintered permanent magnet annealed at different isothermal annealing temperatures Tia(785,800,815,830℃),made of as-homogenized ingot,with the nominal composition Sm(CobalFe0.245 Cu0.07 Zr0.02)7.8(atom fraction%),have been investigated.The results showed that,with the isothermal annealing temperatures increasing from 785℃to 830℃,the remanence Bralmost keeps constant(~1.157 T),the intrinsic coercivity Hcjfirst increases,and then decreases.TEM images indicate that there are two differences between the microstructures of the final state magnet annealed at 785℃ and 815℃,respectively:firstly,the average cell size of the final magnet annealed at 785℃is about 115 nm,while that of the final magnet annealed at 815℃is about 82 nm;secondly,the volume fraction of 1∶5 Hcell boundary phase of the final magnet annealed at 785℃is smaller than that of the final magnet annealed at 815℃.These two reasons above areconsidered to be two main reasons accounting for the maximum Hcjof the final state magnet annealed at 815℃.