具有永磁性能的SmCo₂纳米晶合金化合物的制备与表征

来源期刊：金属学报2010年第8期

论文作者：梁海宁 宋晓艳 张哲旭 卢年端 刘雪梅 张久兴

文章页码：973 - 978

关键词：Sm-Co合金； 纳米晶合金； 相稳定性； 显微结构； 磁性能

Key words：Sm-Co alloy； nanocrystalline alloy； phase stability； microstructure； magnetic properties

摘    要：结合高能球磨和放电等离子烧结技术,通过非晶合金粉末在烧结致密化的同时发生完全纳米晶化的机制,制备出了致密的SmCo₂纳米晶合金块体材料,其平均晶粒尺寸约22 nm.对SmCo₂纳米晶合金化合物的显微组织、晶体结构和相组成等的表征和分析表明,SmCo₂纳米晶合金在室温下不能以单相的形式存在,发生分解形成SmCo₃,Sm₉Co₄和SmCo₂多相共存的合金体系;而粗晶合金可以SmCo₂单相在室温下稳定存在.结合纳米晶热力学计算阐释了粗晶合金和纳米晶合金的相稳定性及其转变规律.对磁性能的测定表明,与同种成分粗晶合金只有微弱的磁性能相比,SmCo₂纳米晶合金表现出明显的永磁特性,且具有良好的综合磁性能.

Abstract: The nanocrystalline SmCo₂ bulk alloy with an average grain size of about 22 nm was prepared by combining high-energy ball milling and spark plasma sintering (SPS),in preparation the amorphous alloy powder obtained by milling was densified and crystallized during the SPS process. The microstructure,crystal structure and phase structure of such SmCo₂ were determined.These results show that the nanocrystalline SmCo₂ is not able to exist stably as a single phase at room temperature and decomposes into SmCo₃ and Sm_gCo₄ phases,different from the conventional coarsegrained SmCo₂ phase,which exists stably at room temperature.Phase stability and transformation behavior have been explained by the nanoscale thermodynamic simulation.Comparing with the coarsegrained SmCo₂ with very weak magnetic properties,the nanocrystalline SmCo₂ exhibits remarkable permanent magnetism and good overall magnetic properties.