Effect of Deformation and Heat Treatment on Microstructure of Al-Mg-Si-Cu Alloy Containing Zr

The microstructure of Al-0.8Mg-1.0Si-0.8Cu-0.3Mn-0.5Fe-0.15Zr alloy sheets during processing and after T6 heat treatment were studied by optical microscopy(OM), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and X-ray diffraction (XRD) analysis. The results indicate that with the increase of deformation, the grains became more and more small and flat during hot rolling. Meanwhile, the quantity of recrystallized grains increased significantly. After cold rolling the coarse second phases fragmented, and the precipitations mainly existing in alloy sheet were Mg2Si, Al9Fe0.84Mn2.16Si, Al8Fe2Si, AlCu and Al3Zr. After T6 heat treatment, grains in the alloy were refined and close to equiaxed, and the precipitation phase sorts did not change except AlCuMgSi phase in comparion with the alloy after cool rolling.