材料期刊网

Ferromagnetic Mn-Al powders were produced by a gas-atomization method followed by heating treatment. The gas-atomized powders were E >-phase, which is a high temperature phase in the Mn-Al system. The E >-tau phase transformation took place by subsequent heat treatment at temperatures from 500 to 700 A degrees C. The gas-atomized powders with a smaller particle size formed the tau-phase faster and thus exhibited better magnetic properties. On the other hand, the annealing temperature and time similarly played important roles in determining the magnetic properties of the products. The Mn-Al powders of 25-38 mu m annealed at 550 A degrees C for 120 min exhibited a high coercivity of 3.2 kOe with a remanence of 38 emu/g.