Magnetic properties of Mn–Al–C alloy powders produced by mechanical grinding

The saturation magnetization of the milled powders gradually decreased as the milling time increased due to the transformation of the magnetic τ phase into the amorphous phase. On the other hand, the coercivity of the milled powders increased to a peak value of 4.35kOe, then decreased with increasing milling time. When the amorphous powders were annealed at relatively high temperatures, the annealed powders consisted mostly of the magnetic τ phase. The optimally annealed Mn–Al–C–Ni powders exhibited a high remanence of 60emu∕g with a coercivity of 1.95kOe, which is comparable to those of the gas-atomized Mn–Al–C–Ni powders.