Cu含量对2:17型SmCo永磁体磁畴结构和矫顽力的影响

Effects of Cu on Domain Structures and Intrinsic Coercivity of 2:17-Type SmCo Permanent Magnets

采用粉末冶金的方法制得2：17型SmCo永磁体，通过对磁体进行X射线衍射（XRD）、振动样品磁强计（VSM）和磁力显微镜（MFM）等分析，较为系统地研究了Cu含量对Sm（CobdlFe0.20CuxZr0.03）75（x=0．06，0．08）永磁体的磁畴结构及矫顽力的影响。研究结果表明，2：17型SmCo永磁体属于多磁畴晶体，其磁畴结构主要表现为波纹畴结构，磁畴宽度约1～2μm，畴宽远小于晶粒尺寸。Cu含量对磁体的X射线衍射谱没有明显影响，但对磁畴宽度和内禀矫顽力。Hc影响很大，且磁畴宽度与内禀矫顽力iHc。具有一定的对应关系。磁体的X射线衍射谱上显示了2：17相和1：5相特征峰，没有出现会影响磁体磁性能相的特征峰。Cu含量增大，X射线衍射谱并未出现明显的变化。随Cu含量增加，磁体磁畴宽度由2μm减小到1μm，1：5胞壁相的畴壁能降低，内禀矫顽力i以相应增大，表明畴壁钉扎是吸引型钉扎。内禀矫顽力iH。在室温时为2473kA·m^-1，到450℃时减小为457kA·m^-1，热激活能是内禀矫顽力；H。随温度升高而逐渐降低的主要因素。高温下Cu含量越高的磁体的2：17主相和1：5胞壁相间畴壁能差越大，从而使矫顽力随温度的升高衰减减缓。

The effects of Cu content on the domain structures and the intrinsic coercivity of 2： 17-type Sm（ CbalFe0.20CuxZr0.03 ）7.5 （x = 0.06, 0. 08） magnets prepared by powder metallurgy process were systematically studied by X-ray diffractometry（ XRD）, vibra- tion sample magnetometer（VSM） and magnetic force microscopy（MFM）. The results showed that 2： 17-type SmCo permanent magnets had multi-domain structures, which were mainly corrugated domains with the width of 1 - 2 μm and far thinner than the cell size. Cu content had little effects on XRD measurements, but had obvious effects on the width of the domain and the intrinsic coercivity iHc. Meanwhile, there was the corresponding relation between the width of the domain and the intrinsic coercivity iHc. There were 2：17 and 1 ： 5 phases but no characteristic peaks of hazardous phase for magnetic properties on the X-ray spectrum and no significant changes on the X-ray spectrum when Cu content increased. With raising Cu content, the width of the domain changed from 2 to 1 μm and the domain wall energy of 1：5 boundary phase decreased while the intrinsic coercivity iHc increased which indicated the attractive domain wall pinning. The intrinsic coereivity was 2473 kA.m^-1 at room temperature and 457 kA.m^-1 at 450 ℃ and the thermal activation energy was the main factor which led to the reduction of the intrinsic coercivity iHc. At high temperature, the higher the Cu content was, the greater the energy difference was between 2：17 phase and 1：5 phase, thus caused slower decrease of the intrinsic coercivity iHc with temperature increasing.