Directional annealing studies on rapidly solidified Sm–Co–Nb–C alloys

Abstract In this paper, a process that develops texture in nanocrystalline permanent magnet alloys is presented. An originally isotropic material is passed through a high up-temperature gradient, inducing directional grain growth. Texture development by directional annealing of melt-spun Sm 12 Co 88 , (Sm 12 Co 88 ) 99 Nb 1 , (Sm 12 Co 88 ) 99 C 1 , and (Sm 12 Co 88 ) 98 Nb 1 C 1 alloys was examined. Samples directionally annealed were compared with conventionally annealed samples. Strong (0 0 6) in-plane texture was observed by X-ray diffraction in Sm 12 Co 88 and (Sm 12 Co 88 ) 99 Nb 1 alloys and the anisotropy was corroborated by magnetic measurements (magnetic texture ∼20–53%). Directional annealing produced only slight texture in the (Sm 12 Co 88 ) 99 C 1 and (Sm 12 Co 88 ) 98 Nb 1 C 1 alloys. The development of texture is critically dependent on annealing temperature, the up-temperature gradient, translational velocity, and alloy composition. The activation energy for anisotropic grain growth was estimated to be ∼28 and ∼42 kJ mol −1 for Sm 12 Co 88 and (Sm 12 Co 88 ) 99 Nb 1 , respectively. These results indicate that directional annealing as a route to texture development in nanocrystalline permanent magnet alloys is a feasible process.