块状纳米晶SmCo5烧结磁体的结构及其磁性能

采用放电等离子烧结(SPS)技术制备致密块状纳米晶SmCo5烧结磁体,研究磁体的结构和磁性能.XRD结果表明:球磨粉末基本为非晶结构,烧结磁体具有CaCu5结构.TEM结果表明:磁体获得晶体均匀分布的组织结构,平均晶粒尺寸约为30 nm.电子选区衍射(SAED)分析表明:磁体主相为SmCO5相.室温时磁体的矫顽力高达2.28 MA/m,而剩磁比Mr/Ms高达0.7,并通过剩磁曲线-M-H及其变化趋势,说明在纳米晶之间存在强烈的晶间交换耦合作用.烧结磁体具有良好的高温性能,773 K时其矫顽力为0.72 MA/m,矫顽力温度系数β为-0.146%/K.

Structure and magnetic properties of bulk nanocrystalline SmCo5 sintered magnet

The bulk nanocrystalline SmCo5 sintered magnet was prepared by spark plasma sintering technique (SPS). The structure and magnetic properties of the magnet were studied. XRD patterns show that the mill powder exhibits amorphous structure and the magnet exhibits CaCu5 structure. TEM observation indicates that the microstructure of the magnet is composed of SmCo5 single phase grains with an average grain size of 30 nm. The magnetic measurement shows that the coercivity of the magnet reaches as high as 2.28 MA/m. The high ratio Mr/Ms of 0.7 demonstrates the existence of strong intergrain exchange coupling among the nanograins. The magnet exhibits a good thermal stability with coercivity of 0.72 MA/m at 773 K, and the coercivity temperature coefficient β of -0.146%/K.