Mechanical properties, intergranular corrosion behavior and microstructure of Zn modified Al–Mg alloys

The effects of the alloying elements Zn on the mechanical properties, intergranular corrosion behavior and microstructure of Al–Mg alloys have been examined. The type, morphology and distribution of the precipitates both at the grain boundary and in the matrix were systematically observed by optical microscopy and transmission electron microscopy. Integrated intergranular corrosion test and transmission electron microscopy results indicated the stable ternary Al–Mg–Zn phase precipitated at grain boundary rather than Al–Mg binary phase with Zn addition to Al–Mg alloy, and discontinuously precipitated at the grain boundary. Also, the area fraction of Al–Mg–Zn phase at the grain boundary decreased with an increase in the Zn content. The intergranular corrosion resistance and strength of the alloy enhanced by Zn addition. In grains, the amount of Al–Mg–Zn phase and Al–Mg increasing with Zn content increases. The Al–Mg phase was found to be nucleation at preexisting Al–Mn phase. Finally, detailed explanation for controlling and optimizing the microstructure in the Zn modified alloy was discussed.