Abstract
The effect of Cu addition on the microstructural evolution and mechanical properties of hypoeutectic Al-10Mg_2Si alloys was investigated. It was found that Cu addition could effectively refine the primary a-Al grain. Simultaneously, the coarse eutectic Mg_2Si was also modified to be fine coral-like. The constitutional supercooling and the multiple nanosized precipitating layers at the edge of the eutectic Mg_2Si cause the branching and refining of the eutectic Mg_2Si through effectively restricting the growth of eutectic Mg_2Si, while the Cu-rich clusters and nanosized precipitates on the surface of the end of the eutectic Mg_2Si prevent the diffusion of the solute atoms such as Al, Mg and Si, and the growth of eutectic Mg_2Si grains is physically limited, resulting in the decrease of the length of eutectic Mg_2Si. The strength and ductility of the Cu-added Al-10Mg_2Si alloys were simultaneously improved, and the fracture failure mode transforms from brittle failure to ductile failure. The mechanism of mechanical properties enhanced by Cu addition was discussed.
NSTL
Elsevier