Morphology of silicon grain boundaries in Sr-modified Al-Si eutectic alloys by HREM

Crystallographic changes in the Σ3〈110〉/{111}, Σ3〈110〉/{112} and Σ9〈110〉/{112} boundaries induced by th presence of strontium in the silicon phase of Sr-modified Al-Si alloys have been studied by high-resolution electron microscopy. The Σ3 boundaries possessing {111} and {112} planes in the pure silicon phase often exhibit asymmetric morphologies in the Sr-modified phase. Interaction of various Σ3〈110〉/{111} boundaries results in both Σ3〈110〉/{112} and Σ9〈110〉/{112} boundaries. The resulting Σ9 boundaries also show asymmetrical inclination.