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

摘要

The reactivity between #gamma#-SiC whiskers andan aluminium alloy (Al-Cu-Mg), both present in a metal matrixcomposite, has been studied when such matrix is in molten state.Using mainly transmission electron microscopy (TEM) andelectron micro-diffraction (ED), the nature and morphology of thereaction products generated at the #gamma#-SiC/aluminiuminterface, when this last melts under different condition whichsimulate casting and welding procedures for metal matrixcomposites, have been characterised. Both the formation ofAl_4C_3 aggregates with platelet morphology generated bydissolution-reaction mechanisms, and aciculate crystals of thesame carbide form by complete dissolution of the #gamma#-SiCwhiskers and later Al_4C_3 precipitation into the moltenaluminium. Ternary Al-Si carbides with high chemical stabilityhave been also identified by TEMED (#gamma#-Al_4SiC_4),being its formation related with higher energetic conditions thanfor the Al_4C_3.