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Mg-Al alloy is popular for its high specific stiffness and specific strength. therefore, the tendency is focus on the improvement of that by alloying process. However, the research in the aging precipitation, especially in early stage, is insufficient.In this paper,the solution treatment of Mg-Al alloy(content of Al is 3wt%、6wt%、9wt%) is carried out at 420℃for 48h.. and then the aging precipitation of the alloy in different temperature. the tendency of aging precipitation(aging kinetics curve) is analysis by conductivity of all samples. through HRTEM, the precipitation process is followed: SSSS (Super Saturated Solid Solution)→Al2Mg(the early stage aging precipitation)→Al12Mg17(the later stage aging precipitation)The main precipitation Al2Mg occurs in the sample(AZ31and AZ61) by electron beam bombardment,and the Al12Mg17 in AZ91. the associated phase is different and show a certain relationship as followed: AZ31:Al2Mg+Mg2Zn11 AZ61:Al2Mg+Mg7Zn3 AZ91:Al12Mg17+Al57Mn12In order to explain the experimental phenomena in theory, the computer simulation is conducted in electron-atom level by MS (Materials Studio and Materials Explorer)soft. The thermodynamic simulation give the different precipitation energy, free energy, zero point energy, enthalpy, entropy and so on in different crystal face. And the simulation result show that (1120),(1121) is the habit plane of precipitation. And the addition of Al、Zn、Mn、Zr、Ca would show a obvious influence on the alloy system. Just for the elements change the distribution of electron cloud, TDOS, PDOS, the property of the alloy is influenced by electronegativity of trace element, atomic radius, the stability of alloy system.
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