Homogenization treatment and microstructure of semicontinous casting ingot of 2D70 heat-resistance aluminum alloy

The constituents of the semicontinuous casting ingot of 2D70 heat-resistance aluminum alloy and homogenization treatment were studied by optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), differential scanning calorimetry(DSC) and X-ray diffraction analysis (XRD). The results indicate that the semicontinuous casting ingot of 2D70 aluminum alloy presents a dendritic microstructure with severe segregation. The phases of the nonequilibrium eutectic are α(Al)+ θ(Al2Cu) + S(Al2CuMg) whose overheating temperature is 505.4°C. The volume fraction of hard dissolve phases such as Al7Cu2Fe, Al7Cu4Ni and Al9FeNi changes a little below 530°C. The reasonable homogenization treatment process of the alloy is (490°C, 16 h) +(520°C, 16 h).