The effect of Cu addition and solution heat treatment on the microstructure, hardness and tensile properties of Al-15%Mg2Si-0.15%Li composite

This study has been carried out to investigate the effect of Cu addition (0.1-3 wt%) on the microstructure, hardness and tensile properties of Al-15%Mg2Si-0.15%Li in-situ metal matrix composite before and after solutionizing heat treatment. It was found that the presence of Cu at higher concentrations (>1 wt%) results in the formation of hard Cu-rich intermetallics segregated in cell boundaries which intensifies ultimate tensile strength (UTS) values, but reduces elongation percentage (El%). Further results revealed that solution heat treatment partially dissolves different types of intermetallics which leads to proper distribution of such hard particles and ductility enhancement. The study of the fracture surfaces of the heat treated specimens via scanning electron microscopy (SEM) revealed fine dimples which are the main characteristic of ductile fracture mode.