Microstructure and magnetic properties of anisotropic Mn-Bi powder prepared by low energy ball milling assisted with polyvinylpyrrolidone

The excellent anisotropic Mn55Bi45 powder was prepared by arc melting and surfactant-assisted low-energy ball milling (LEBM). The microstructure and magnetic properties of the alloy were investigated. The ionic polyvinylpyrrolidone (PVP) was selected as a surfactant. The results show that the addition of PVP can improve the low-temperature phase (LTP) content and magnetic properties of the Mn55Bi45 alloy. The coercivity (H-cj) of the anisotropic Mn55Bi45 powder is 14.7 kOe, the maximum energy product ((BH)(max)) is 7.1 MGOe and the saturation magnetization (M-s) is 57.5 emu/g when it is 10 wt% PVP and after 3 h ball milling. The angle dependence of coercivity shows that mechanism of anisotropic Mn-Bi alloy follows to the Stoner-Wohlfarth model.