The quenching, fracture and aging treatment of radially oriented Sm_2Co_(17) ring magnets were investigated. The results indicate that the ring magnets have obvious anisotropy of thermal expansion, which easily leads ...The quenching, fracture and aging treatment of radially oriented Sm_2Co_(17) ring magnets were investigated. The results indicate that the ring magnets have obvious anisotropy of thermal expansion, which easily leads to the splits of the magnets during quenching. The fracture is brittle cleavage fracture. The difference (?a) of the expansion coefficient reaches the maximum value at 800-850 ℃. So, various quenching processes at different steps are adopted in order to reduce the splits. When the magnets are aged, 1:5 phase precipitates from the 2:17 matrix phase and forms a cellular microstructure with 2:17 phase. BHmax and JHc reach the maximum value 226 kJ/m3 and 2 170 kA/m after being aged at 850 ℃ for 4 h and 8 h, respectively. The aging treatment at 850 ℃ has little influence on remanence(Br), which can always keep a high value (≥1.0 T). Through appropriate heat treatment, the ring magnets have uniform cellular microstructure and excellent magnetic properties: Br≥1.0T, JHc≥2 100 kA/m, BHmax≥220 kJ/m3.展开更多
基金Project(20040008015) supported by the Specialized Research Fund for the Doctoral Program of Higher EducationProject supported by the Program for New Century Excellent Talents in University, China
文摘The quenching, fracture and aging treatment of radially oriented Sm_2Co_(17) ring magnets were investigated. The results indicate that the ring magnets have obvious anisotropy of thermal expansion, which easily leads to the splits of the magnets during quenching. The fracture is brittle cleavage fracture. The difference (?a) of the expansion coefficient reaches the maximum value at 800-850 ℃. So, various quenching processes at different steps are adopted in order to reduce the splits. When the magnets are aged, 1:5 phase precipitates from the 2:17 matrix phase and forms a cellular microstructure with 2:17 phase. BHmax and JHc reach the maximum value 226 kJ/m3 and 2 170 kA/m after being aged at 850 ℃ for 4 h and 8 h, respectively. The aging treatment at 850 ℃ has little influence on remanence(Br), which can always keep a high value (≥1.0 T). Through appropriate heat treatment, the ring magnets have uniform cellular microstructure and excellent magnetic properties: Br≥1.0T, JHc≥2 100 kA/m, BHmax≥220 kJ/m3.
