Studies on the formation, structure and magnetic properties of Cr substituted Sm-2(Fe,Cr)(17)C-x compounds

The effects of Cr substitution on the formation, structure and magnetic properties of Sm-2(Fe, CT)(17)C-x compounds have been systematically studied on are-melted and melt-spun samples using XRD, TEM and magnetic measurements. It has been found that Cr substitution is an effective way to form the Sm-2(Fe, Cr)(17)C-x carbides. The minimum Cr amount for Sm2Fe17-yCryC2 to form an almost single 2:17 phase is around y=2 and the maximum carbon amount for Sm2Fe15Cr2Cx to remain in a single 2:17 structure is around x=2. Magnetic measurements reveal that the Cr substituted Sm-2(Fe, Cr)(17)C-x carbides have a strong uniaxial magnetocrystalline anisotropy with anisotropy fields higher than 90 kOe obtained in Sm2Fe15Cr2C2 and Sm2Fe14Cr3C2 carbides. However, both the Curie temperature and the magnetization are found to decrease with Cr substitution. High coercivity can be obtained in Sm-2(Fe, Cr)(17)C-x ribbons produced by the melt-spinning technique. The highest coercivity of 13.2 kOe has been obtained in Sm2Fe15Cr2C2 ribbons spun at 52 m/s and annealed at 750 degrees C for 20 min.