Interfacial reactions in an Al-Cu-Mg (2009)/SiCw composite during liquid processing - Part II - Arc welding

This paper reports a study of the interfacial reactions occurring in an alu minium alloy composite (AA2009) reinforced with 15% volume in SiC whiskers, under high energy fusion conditions. The composite was subjected to meltin g processes that simulated a secondary composite manufacture technique such as arc welding. The different reaction mechanisms between the SiC whiskers and both the molten aluminium and their alloying elements (Cu, Mg, and Fe) are discussed. The high aspect ratio (l/d) of the reinforcement is the mai n microstructural factor, which controls the weldability of this kind of co mposite, having more influence than the actual interfacial reactivity. Unde r the highest welding inputs applied, the formation of both a binary alumin ium carbide (Al4C3) and a ternary one (beta -Al4SiC4) was detected in the t op of the molten pools. It is observed that these ternary carbides are hard er and more chemically stable than the Al4C3, which is formed at lower temp eratures. (C) 2001 Kluwer Academic Publishers.