Hf、CNTs混合掺杂对纳米晶Sm5Co19合金结构和磁性能的影响

对制备出纳米晶组织的Sm_5Co_(19)Hf_(0.4)合金和Sm_5Co_(19)Hf_(0.4)CNTs_(0.4)合金的显微组织、晶体结构和磁性能等进行了系统表征分析。结果表明:Hf元素和碳纳米管(CNTs)的混合添加不引起Sm_5Co_(19)合金Ce_5Co_(19)型结构发生相分解,且使纳米晶组织中的晶粒变得细小,晶粒尺寸均匀分布。能谱分析表明,添加的CNTs进入纳米晶Sm_5Co_(19)Hf_(0.4)CNTs_(0.4)合金的晶界区域,产生晶界钉扎作用,显著提高纳米晶Sm_5Co_(19)合金的矫顽力。晶体结构精修表明,Hf元素进入纳米晶Sm_5Co_(19)合金晶胞结构的Sm空位,导致晶格参数a、b、c均减小,而轴比c/a增加,使Hf掺杂的纳米晶合金的磁晶各向异性增大,具有提高纳米晶合金的矫顽力的作用。本研究结果对设计制备具有高磁晶各向异性、高内禀矫顽力的Sm-Co基合金具有明确指导意义。

Effect of Alloy Structure and the Magnetic Mix Doping Hf Elements and CNTs on Nanocrystalline Sm5Co19 Alloy

In this study, permanent magnetic nanocrystalline Sm₅Co₁₉Hf_0.4 alloy and Sm₅Co₁₉Hf_{0. 4}CNTs_{0. 4} alloy with high room-temperature coercivity were produced. The microstructure, crystal structure and magnetic were studied. The results show that the Hf elements and CNTs mixed added did not lead to phase decomposition of Ce₅Co₁₉ type structure, meanwhile the microstructure possess fine grain size and uniform distribution. Energy Dispersive X-ray Spectrometry (EDX) analysis confirmed that CNTs move into grain boundaries of the nanocrystalline Sm₅Co₁₉Hf_0.4CNTs_0.4alloy, which can improve the coercivity of the nanocrystalline Sm₅Co₁₉ alloy for the grain boundary pinning effect. Rietyeld refinement showed that Hf comes into the Sm vacancy decreasing the lattice parameters and increasing the axial ratio c/a , which furtherly enhance the magnetocrystalline anisotropy , thus strengthen the coercivity of nanocrystalline alloy. In this paper, the results of the study can promote the design of Sm-Co alloy with high magnetocrystalline anisotropy and intrinsic coercivity.