Phase constituent in as-cast microstructure and microstructure of the semi-continuous 2D70 aluminum alloy in as-cast

normal homogenization and high temperature homogenization were observed by optical microscope（OM）

SEM（scanning electron microscope）

EDS（energy dispersive spectrum）

XRD（X-ray diffraction）and DSC（differential scanning calorimetry）.The results reveal that as-cast microstructure of the alloy is composed of Al2CuMg

Al2Cu

Al9FeNi

Al7Cu2Fe

Al7Cu4Ni phase

presenting amounts of non-equilibrium eutectic phases.DSC and XRD analysis indicate that after one-step homogenization treatment

Al2CuMg phase can be dissolved into the alloy with the presence of some high melting point eutectic phase

and the initial melting temperature of Al2Cu phase is increased

which provides a base for two-stage homogenization treatment.Eutectic phase with melting point is fully dissolved into the alloy after two-sage homogenization treatment.In addition

change of Al9FeNi

Al7Cu2Fe

Al7Cu4Ni phase in the ingot is not observed during homogenization process.