Al晶界的第一性原理拉伸试验

基于密度泛函理论和局域密度近似的第一性原理方法，进行了Al晶界的第一性原理拉伸试验.得到Al晶界的理论拉伸强度为9.5 GPa，对应的应变为16%.根据价电荷密度、键长和原子构型随应变的变化，我们证实断裂发生在晶界面，其特征是所有界面键的断裂.同时还发现在周围原子键的数目减少的情况下，界面重构的Al-Al原子键具有共价键的性质.因此Al晶界依然保持着较高的界面强度.关键词：Al晶界第一性原理拉伸试验理论拉伸强度

First-principles computational tensile test on an Al grain boundary

Using a first-principles total energy method based on density functional theory within local density approximation, we have performed a first-principles computational tensile test (FPCTT) on an Al grain boundary. The theoretical tensile strength of the Al grain boundary is calculated to be 9.5 GPa at the strain of 16%. Based on the valence charge density, bond length and atomic configuration evolution with increasing strain, we demonstrate that the fracture occurs at the grain boundary interface,characterized by breaking of the grain boundary interfacial-reconstructed bonds. We further found that, because of the reduced number of the nearest neighbor of Al atoms in the grain boundary, these interfacial-reconstructed bonds have similar features to covalent bonds, which results in rather high grain boundary strength in comparison with the Al bulk.