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

Abstract

Mn55Bi45+x at.% 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 for x = 0 and 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 πMr) of 7.1 kG, and energy product (BH)max of 11 MGOe have been obtained for the 8 hours milled Mn55Bi45+7 at.% Mn sample. These Mn-Bi powders have potential use as precursor for rare earth free permanent magnets.