Influence of second-phase morphology and topology on mechanical and fracture properties of Al-Si alloys

Mechanical behaviour of eutectic Al-Si alloys with different Si particle topology and morphology modified by heat treatment has been studied. The alloy chosen was a model system for understanding the influence of morphological and topological features on macroscopic mechanical properties. The heat treatment was used to transform a percolated structure of Si platelets and needles into an ensemble of well separated spheroidised particles. Different modes of fracture were observed depending on the particle morphology and on the testing temperature. The as-cast specimens appeared to be softer and showed higher ductility than those with spheroidised particles.