Cerium-based RCo5 (R = Ce, La0.35Ce0.65, and misch-metal) type nanocrystalline hard magnetic materials with high coercivity

摘要

Nanocrystalline R Cosub5/sub ( R = Ce, Lasub0.35/subCesub0.65,/sub and misch-metal noted as MM) ribbons with hexagonal crystal structure and an average grain size of 5 nm have been prepared via a one-step melt-spinning technique. Coercivity as high as 13.0, 13.8, and 10.9 kOe has been obtained at 300 K for the CeCosub5/sub, Lasub0.35/subCesub0.65/subCosub5/sub, and MMCosub5/sub ribbons, respectively. High thermal stability is also achieved as shown by the high coercivity of 9.3 kOe, 10.2 kOe, and 8.8 kOe at 400 K for CeCosub5/sub, Lasub0.35/subCesub0.65/subCosub5/sub, and MMCosub5/sub ribbons, respectively. The coercivity mechanism is studied by magnetization analysis and microstructural observations. The nanocrystalline grains promote a strong exchange interaction, as indicated by the positive δM and the relatively high remanence ratio (～0.8). In addition, the temperature dependence of coercivity of R Cosub5/sub ribbons shows the low coercivity temperature coefficient of ?0.2% to ?0.25%/K.