Al-Mg-Si合金GP区及β相界面电子结构分析

Analysis of Interface Electron Structures of GP Zones and β Phase in Al-Mg-Si Alloy

关键词:  Al-Mg-Si合金  GP区  β相  界面电子结构

Key words:  Al-Mg-Si alloy  GP zones  β phase  interface electron structures

摘要:

运用EET理论对Al-Mg-Si合金GP区(L₁₀型,下同)、β相(Mg₂Si)与基体的界面电子结构进行计算,着重从界面电子角度反映时效过程中GP区、β相与基体的界面结合性质、界面原子状态变化及界面对合金有关力学性能的影响,并分析原子状态变化的原因。结果表明:Al-Mg-Si合金GP区与基体界面电子密度在一级近似下连续,GP区粒子易于长大,而β相不连续,抑制了β相再结晶晶粒的长大,但它在高应力下呈现连续,从而提高合金变形抗力。当界面最稳定时,GP区与基体界面的结合强于β相与基体界面的结合,当界面处于非稳定的临界状态时,与最稳定状态相比,GP区与基体界面结合能力下降,而β相升高。最稳定状态下的界面与体内各原子杂阶相比,GP区界面各类原子杂化能级总体上升,β相界面各类原子状态没有变化;当基体界面电子密度由最小值过渡到最大值时,GP区与β相中Si原子的杂阶均降低;GP区界面处基体Al原子的杂阶不变,但β相界面处基体Al原子的杂阶上升。

Abstract:

The electron structures of the interface between GP zone with L₁₀ structure (the same in later) and the matrix and the interface between β phase and the matrix in Al-Mg-Si alloy were calculated using the Empirical Electronic Theory in solid and molecules (EET).The interaction properties of the interface between GP zone and the matrix and the interface between β phase and the matrix, the changes of states of interface atoms, the effects of interfaces on mechanical properties during aging and the reason of atomic states change were analyzed based on interface electronic theory.The results suggest that the electron density of the interface between GP zone and the matrix is coherent under the first order approximation, thus particles of GP zone are prone to growing, while β phase is not coherent, which will restrain recrystalization particles of β phase from growing, however β phase is coherent to enhance resistance to deformation of the alloy under high stress.The interaction of the interface between GP zone and the matrix is stronger than the interaction of β phase and the matrix when the interface is in the steadiest state.When the interface is in the critical metastable state, the bond ability of GP zone and the matrix will decline, however the bond ability of β phase and the matrix will increase comparing with the steadiest state.The atomic hybridizations of GP zone interface increase and the atomic hybridization of β phase interface stayed unchanged comparing with atomic hybridization of the matrix in the steadiest state.When the electron densities of the matrix change from the smallest to the largest, both Si atom hybridization of GP zone and β phase decrease, the hybridizations of Al atoms in GP zone interface won't change, but the hybridizations of Al atoms in β phase interface will increase.