Microstructural and mechanical characterization of a stainless-steel wire mesh–reinforced Al-matrix composite

Bimatallic components for lightweight design

Abstract

The microstructure and mechanical properties of stainless-steel AISI 304 wire mesh–reinforced AlSi9Cu-matrix composite specimens obtained by gravity casting were investigated. Optical and scanning electron microscope analyses were carried out on samples in both as-cast and solution heat treated conditions. The obtained results showed the absence of intermetallic phases at the insert/Al-matrix interface but even a significant fraction of lack-of-filling defects as well as lack-of-bonding areas that weekend the interface itself. The solution heat treatment, on the other hand, induced the precipitation of a thick and brittle intermetallic layer in the areas where a metallurgical bonding formed during casting. Moreover, the silicon particle spheroidization, improved the ductility of the matrix. The resulting microstructure allowed to obtain a slight improvement of elongation at failure of the compound casting compared to that of the aluminum alloy. Finally, basing on the obtained results, improvements are suggested that take into account both the preconditioning of the reinforcement surface and its geometry.