The Mechanical Research Of Solid State Phaes Transformation And Its Effects On Properties In Al-Cu-Mg Alloy

Al-Cu-Mg alloys have excellent performances, such as high specific strength, high specific modulus, good corrosion resistance and high temperature properties. They are widely used in aerospace as a new kind of structural material. However, the study for the microscopic mechanism of structure and properties in Al-Cu-Mg alloys is still in exploration stage now.The valence electron structures and interface electron structures in all kinds of segregating cells and part of precipitate phases during aging in Al-Cu-Mg alloys were analyzed systematically using the Empirical Electronic Theory in solid and molecules (EET) and improved TFD method by Cheng Kaijia. The research work made it possible to further study as theoretical method. The main contents of this paper are as follows:Firstly, the models for valence electron structures of phases in Al-Cu-Mg alloys were established. There are five kinds of cells in Al-Cu-Mg alloys: α-Al cell; Al-Cu cell; Al-Mg cell; Al-Cu-Mg cell and all kinds of cells containing vacancies. The valence electron structures of above cells were calculated based on the average atom model. The results suggest that there are more valence electrons in ternary segregating cells, which can strengthen the matrix. Especially, the energy level of solute atom is lower in the segregating cells containing vacancy, thus the free energy is lower too, and so the embryos or precursor structure will first form in the segregating cells containing vacancies.Secondly, the valence electron structures of G.P.B zone, S" phase and S phase in supersaturated solid solution during aging were calculated in Al-Cu-Mg alloys. The phase transformation from GP.B zone to S" phase was interpreted reasonably based on valence electron structures. And then,...