Mechanical alloying and milling of Al-Mg alloys

Solid solubility extension of Mg in Al was achieved for the binary Al-Mg system in the range of 10-40 at.% Mg by mechanical alloying of elemental powder mixtures and by mechanical milling of pre-alloyed ingots. No indication for the formation of the equilibrium phases (beta-Al(3)Mg(2) and gamma-Al(12)Mg(17)) after milling was observed. The cell parameters of the solid solutions increase linearly with increasing Mg content with a slope that depends on the processing route used. During heating, the Al(Mg) solid solutions prepared from the different starting materials display a complex behavior characterized by several exothermic events. At low temperatures, an increasing amount of Mg is rejected from the solid solution with increasing temperature. At higher temperature, the beta'-phase, a hexagonal intermediate phase with approximate composition Al(3)Mg(2), is formed. The beta'-phase most likely serves as precursor for the formation of the equilibrium beta-Al(3)Mg(2) phase, which occurs in the following exothermic event. (C) 2008 Elsevier B.V. All rights reserved.