Effect of Mg on the sintering of Al-Mg alloy powders by pulse electric-current sintering process

Utilization of deoxidization mechanism of magnesium (Mg) is an effective method to remove the oxide films at aluminum (Al) alloy powder surface in pulse electric-current sintering (PECS) process. The continuous amorphous oxide film at Al alloy surface are broken and removed by deoxidization of Mg. Crystalline particles of MgAl2O4 or MgO, or both of them, are formed, which depend on Mg content in Al alloy powder and sintering temperature. After that the metal/metal contact is caused, and solid state sintering of Al alloy powder is facilitated. The electrical resistivity and tensile properties of powder compacts are improved by Mg addition. Based on the analyses of electrical resistivity, tensile properties and microstructures of the sintered specimens, optimum amount of Mg addition to improve the sintering properties of Al powder is determined to be 0.3-2.5 mass%.