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 aluminium alloy composite (AA2009) reinforced with 15% volume in SiC whiskers, under high energy fusion conditions. The composite was subjected to melting 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 main microstructural factor, which controls the weldability of this kind of composite, having more influence than the actual interfacial reactivity. Under the highest welding inputs applied, the formation of both a binary aluminium carbide (Al4C3) and a ternary one (β-Al4SiC4) was detected in the top of the molten pools. It is observed that these ternary carbides are harder and more chemically stable than the Al4C3, which is formed at lower temperatures.