Microstructural characterization of as-cast and homogenized 2D70 aluminum alloy

Abstract

The microstructure of the as-cast 2D70 aluminum alloy and its evolution during homogenization were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The results indicate that the microstructure of the as-cast 2D70 aluminum alloy mainly consists of the dendritic network of aluminum solid solution and intermetallic compounds (Al 2CuMg, Al 2Cu, Al 9FeNi, Cu 2FeAl 7, and Al 7Cu 4Ni). After conventional homogenization, Al/Al 2CuMg eutectic phases are dissolved into the matrix, and a small amount of high melting-point eutectic Al/Al 2Cu phases exist in the matrix, resulting in an increase in the starting melting temperature. Under double homogenization, the high melting point Al/Al 2Cu phases are dissolved, and no obvious change is observed for the size and morphology of Al 9FeNi, Cu 2FeAl 7, and Al 7Cu 4Ni compounds.