Characterizing Microstructure Evolution and Correlated Properties of an Al–Mg–Si Alloy during Nonisothermal Aging

The microstructure evolution, mechanical properties and corrosion properties of Al–Mg–Si alloy during nonisothermal aging (NIA) were studied. The results show that as the aging time increases, the hardness, electric conductivity and the intergranular corrosion (IGC) resistance of the alloy increase, which relates to changes of microstructures. GP zones are primary formed in the initial heating stage. In the cooling stage, high-density, needle-like β" are main precipitates. The alloy through NIA treatment exhibits excellent mechanical properties and satisfactory corrosion resistance, resulting from the combination effects of the growth of original β" in the heating stage, the new formation of fine β" phase and the coarsening grain boundary precipitates during the cooling process.