INFLUENCE OF 2ND-PHASE MORPHOLOGY AND TOPOLOGY ON MECHANICAL AND FRACTURE PROPERTIES OF AL-SI ALLOYS

Mechanical behaviour of eutectic Al-Si alloys with different Si partic le 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 pr operties. The heat treatment was used to transform a percolated struct ure of Si platelets and needles into an ensemble of well separated sph eroidised particles. Different modes of fracture were observed dependi ng on the particle morphology and on the testing temperature. The as-c ast specimens appeared to be softer and showed higher ductility than t hose with spheroidised particles. (C) 1997 Elsevier Science S.A.