Effect of reaction temperature and holding time on the interfacial microstructure of Al–Si–Mg/Cu bimetals manufactured by hot-dip aluminizing

Abstract

This study investigates the effects of reaction temperature and holding time on intermetallic compounds (IMCs) at the Al–Si–Mg/Cu bimetals interface fabricated by hot-dip aluminizing. Previous research has demonstrated that the presence of IMC layers in Al–Si–Mg/Cu bimetals significantly increased the interface hardness. This study aims to achieve a continuous change in hardness at the interface by forming Cu3Al layers, thus exhibiting the lowest hardness and highest ductility among the Al–Cu IMCs. The thickness and morphology of the Al–Cu IMC layer depend on the reaction temperature and holding time. Al–Cu intermetallic phases with higher Cu contents, such as Cu3Al, Cu9Al4, Cu3Al2, CuAl, and CuAl2, were closer to the Cu surface. The formation of Cu3Al leads to continuous changes in the hardness of the Cu and IMC layers. Furthermore, the growth kinetics of IMCs and their formation mechanisms are discussed. The results indicate that hot-dip aluminizing is an effective method for controlling the composition and thickness of the IMC layer to achieve a continuous change in the interfacial hardness.