材料期刊网

The hot deformation process of cast Pr_(19)Fe_(74.5)B_5Cu_(1.5) magnets were studied.It is found that the easy-axes are aligned parallel to the compressive strain direction in vari- ous hot deformation process.During hot deformation,the crushing of Pr_2Fe_(14)B matrix grains and the relative slip and rotation between the grains take place and the Pr-rich melt is squeezed out of the magnet,leading to a fine,dense and well-aligned microstruc- ture in the fully-deformed magnets.Magnetic properties of B_r=990 mT,_iH_c=880 kA/m and(BH)_m=191 kJ/m~3are obtained.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 boundaries.The increasing remanence is resulted primarily from the develop- ment 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 the good easy-axis alighnment and high magnetic properties.