Effect of a Si Additive on an Al Grain Boundary: A First-Principles Investigation

The electronic structure of an Al grain boundary (GB) with Si as an additive has been investigated by a first-principles method. Si has been found to increase the charge density around itself and along the GB, and such increase can be enhanced with increasing Si concentration. Same effect occurs when Si is added in an Al GB with segregated Na impurity. The results suggest a possible strengthening effect of Si on the Al GB, and Si thus can be a good candidate additive for suppressing the Al intergranular embrittlement caused by impurity segregation.