The formation mechanism of 1:5H phase in Sm(Co, Fe, Cu, Zr)z melt-spun ribbons with high iron content

Abstract

The formation of 1:5H phase in Sm (Co, Fe, Cu, Zr)z melt-spun ribbons with high iron content has been investigated. The precipitation of the Zr-rich 2:7R phase is restrained in the boundaries of 2:17H grains for the as-spun ribbon. After aging treatment, only 2:17R phase with planar 1:3R phase occurs, which results in a lower coercivity of around 1.03kOe. After solid solution treatment of the as-spun ribbon, 2:17R phase with lower ordered state together with minor 2:17H phase is obtained. In addition, the ribbon after solid solution consists of large numbers of 2:17R nanotwins. When different twin variants with various stacking sequence encounter each other, those areas which are rich in Sm will act as the nucleation centers of 1:5H phase during aging. The pinning strength for the magnetic domain walls is enhanced, thus leading to a much higher coercivity of 6.16 kOe. These results may provide guidance for high performance 2:17R SmCo permanent magnets with high iron content.