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

Abstract

The effects of Cr substitution on the formation, structure and magnetic properties of Sm 2(Fe, Cr) 17C x compounds have been systematically studied on arc-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) 17C x carbides. The minimum Cr amount for Sm 2Fe 17− y Cr y C 2 to form an almost single 2 : 17 phase is around y = 2 and the maximum carbon amount for Sm 2Fe 15Cr 2C x to remain in a single 2 : 17 structure is around x = 2. Magnetic measurements reveal that the Cr substituted Sm 2(Fe, Cr) 17C x carbides have a strong uniaxial magnetocrystalline anisotropy with anisotropy fields higher than 90 kOe obtained in Sm 2Fe 15Cr 2C 2 and Sm 2Fe 14Cr 3C 2 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) 17C x ribbons produced by the melt-spinning technique. The highest coercivity of 13.2 kOe has been obtained in Sm 2Fe 15Cr 2C 2 ribbons spun at 52 m/s and annealed at 750°C for 20 min.