Comparison on the magnetic properties and phase evolution of melt-spun SmCo7 ribbons with Zr and Hf substitution

The magnetic properties, phase evolution and microstructure of melt-spun SmCo7−xHfxCy and SmCo7−xZrxCy (x = 0–0.4; y = 0 and 0.1) ribbons have been investigated. The phase transformation and microstructure of the ribbons with Hf substitution are similar to those with Zr. The ribbons with Hf substitution and a slight C addition exhibit a much higher coercivity and energy product than the Zr and C-containing ribbons, because Hf substitution is more effective in increasing the anisotropy field of 1:7 phase than Zr substitution.