Mn-Bi Magnetic Powders With High Coercivity and Magnetization at Room Temperature

Mn₅₅ Bi₄₅+ xat.% Mn (x=0, 7 and 11) magnetic powders were prepared by low energy ball milling technique. The x-ray diffraction pattern showed that the samples mainly contain over 90% of the low temperature Mn-Bi phase forx= 0and 7 with a very small amount of Bi phase. Microstructural analysis showed that the amount of sub-micron particles increases with milling time. The milling time dependent magnetic properties were studied for all the compositions. An intrinsic coercivity( Hci)of 12.2 kOe, remanent magnetization(4 π Mᵣ)of 7.1 kG, and energy product( BH)ₘₐₓof 11 MGOe have been obtained for the 8 hours milledMn₅₅ Bi₄₅+7at.% Mn sample. These Mn-Bi powders have potential use as precursor for rare earth free permanent magnets.