Reactivity on alpha-SiC whiskers and aluminium in liquid processing of metalic matrix composite materials

The reactivity between alpha-SiC whiskers and an aluminium alloy (Al-Cu-Mg) , both present in a metal matrix composite, has been studied when such matr ix is in molten state. Using mainly transmission electron microscopy (TEM) and electron microdiffraction (ED), the nature and morphology of the reacti on products generated at the alpha-SiC/aluminium interface, when this last melts under different condition which simulate casting and welding procedur es for metal matrix composites, have been characterised. Both the formation of Al4C3 aggregates with platelet morphology generated by dissolution-reac tion mechanisms, and aciculate crystals of the same carbide form by complet e dissolution of the alpha-SiC whiskers and later Al4C3 precipitation into the molten aluminium. Ternary Al-Si carbides with high chemical stability h ave been also identified by TEM-ED (beta-Al4SiC4), being its formation rela ted with higher energetic conditions than for the Al4C3.