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通过基于密度泛函理论(DFT)的第一性原理计算了纯金属Al和Al Mg合金在(111)[112]滑移系的层错能和孪晶形变能,分析了Mg含量、占位对层错能和孪晶形变能的影响.计算选用了局域密度近似(LDA)和广义梯度近似(GGA PW91)2种近似方法,发现GGA PW91所获得的层错能与实验结果符合较好,研究结果表明,纯Al的层错能高于孪晶形变能,随着孪晶层厚度的增加孪晶形变能略有提高,6层呈完全镜面对称孪晶有的孪晶形变能最低:Mg含量增加使Al-Mg合金的层错能、变形孪晶形变能明湿降低;Mg在Al-Mg合金中占位对结合能和形成热的影响很小,当Mg处于层错层时略使层错能和孪晶形变能提高.
The stacking fault energy and twin deformation energy of pure Al and Al Mg alloys in (111) [112] slip system were calculated by the first principle based on density functional theory (DFT). The effects of Mg content, On the stacking fault energy and twin deformation energy.Selecting two kinds of approximate methods of local density approximation (LDA) and generalized gradient approximation (GGA PW91), we found that the stacking fault energy obtained by GGA PW91 is in good agreement with the experimental results The results show that the stacking fault energy of pure Al is higher than that of twin, and the twin deformation can be slightly increased with the thickness of twinned layer. The increase of Mg content makes the Al-Mg alloy layer delamination energy and the deformable twin deformation dewetting wetly; Mg has little effect on the binding energy and heat of formation in the Al-Mg alloy. When Mg is in the staggered layer So that stacking fault and twin deformation can be improved.