铸造Pr—Fe—B磁体的热压变形研究

研究了铸造Pr_(19)Fe_(74.5)B_5Cu_(1.5)磁体的热压变形过程,结果表明,无论经受何种变形方式,磁体易轴001]总是沿压缩变形方向取向排列,随着热压变形的进行,磁体发生Pr_2Fe_(14)B主相晶粒的碎化和晶粒间相对滑动和转动,以及富Pr液相被挤出,最终形成细小、致密的取向组织,磁性能提高到B_r=990mT,i_H_c=880kA/m和(BH)_m=191kJ/m~3矫顽力的提高归因于主相晶粒碎化和富Pr相在晶间均匀连续分布,剩磁的提高则主要由已碎化晶粒在变形中相对滑动和转动所形成的易轴取向排列以及主相晶粒的致密化贡献,变形充分而缓慢应是获得较强易轴取向和较高磁性能的重要条件。

HOT DEFORMATION OF CAST Pr-Fe-B MAGNETS

Whatever the cast Pr_(19)Fe_(74.5)B_5Cu_(1.5) magnet deforms in various processes, its easy-axes are aligned parallel to the compressive strain direction. During hot deformation, the crushing of Pr_2Fe_(14)B matrix grains, the relative slip and rotation between the grains and the squeezing out of Pr--rich melt of the magnet take place. Then a fine, dense and well--aligned microstructure may be formed in the fully deformed magnets with improved properties, B_r=990 mT, _iH_c=880 kA / m and (BH)m=191 kJ / m~3. The increase of coercivity is attributed to the fine Pr_2Fe_(14)B grains and the thin Pr--rich phase layer continuously distributed at the grain bounbaries. The increasing remanence is resulted primarily from the development of the easy--axis alignment as well as from the densification of the Pr_2Fe_(14)B matrix. The easy--axis alignment is developed by the relative slip and rotation of the crushed Pr_2Fe_(14)B grains. A full and slow hot deformation is necessary for a good easy--axis alignment and high magnetic prop- erties.