Correlation of microstructure and magnetic properties in Sm(CobalFe0.1Cu0.1Zr0.033)6.93 magnets solution-treated at different temperatures

• Published in: Rare metals 2019-01, Vol.38 (1), p.20-28
• Main Authors: Xu, Cheng, Wang, Hui, Zhang, Tian-Li, Popov, Alexander, Gopalan, Raghavan, Jiang, Cheng-Bao
• Format: Article
• Language: English
• Subjects: Biomaterials; Cellular structure; Chemistry and Materials Science; Coercivity; Energy; Magnetic properties; Magnetism; Magnets; Materials Engineering; Materials Science; Metallic Materials; Microstructure; Nanoscale Science and Technology; Phase transitions; Physical Chemistry; Powder metallurgy; Precipitates; Recoil; Zirconium
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-018-1182-z

The correlation of microstructure and magnetic properties in Sm(Co bal Fe 0.1 Cu 0.1 Zr 0.033 ) 6.93 magnets solution-treated at different temperatures was systematically investigated. It is found that the magnets solution-treated at 1219 °C possess a single 1:7H phase, exhibiting the homogeneous cellular structure during further aging treatment, leading to the optimum magnetic properties. However, for the magnets solution-treated at 1211 and 1223 °C, 2:17H or 1:5H secondary phase will also form besides 1:7H main phase, which cannot transform into cellular structure, thus deteriorating the magnetic properties greatly. The irreversible magnetization investigations with recoil loops also propose a non-uniform pinning in the magnets induced by the secondary precipitates. At proper solution temperature, Zr is supposed to occupy the Fe–Fe dumbbell sites in the form of Zr-vacancy pairs, leading to the minimum c / a ratio and thus stabilizing the 1:7H phase. Finally, Sm(Co bal Fe 0.1 Cu 0.1 Zr 0.033 ) 6.93 magnets with the maximum energy product and intrinsic coercivity at 550 °C up to 60.73 kJ·m −3 and 553.88 kA·m −1 were prepared by powder metallurgy method.