Structure and magnetic properties of MnAl/α-Fe nano-composite powders prepared by high-energy ball milling

Novel nano-composite powders composed of hard-magnetic Mn54Al46 and soft-magnetic alpha-Fe were prepared by high-energy ball milling. The effect of alpha-Fe and preparation conditions on the structure and magnetic properties of the composite powders has been investigated. The epsilon-MnAl transforms to gamma-MnAl, tau-MnAl, and beta-phase under ball milling and annealing. The saturation magnetization and coercivity of the two-phase samples decrease with increasing temperature for the tau-phase decomposes at elevated temperatures. With increasing iron content, the coercivity decrease first and then increase up to 0.33 T when the Fe content is 10 wt%. Further addition of the magnetically soft iron phase would result in a decrease of the coercivity.