Microstructural Evolution of High Purity Al-Cu-Mg Alloy during Homogenization

Abstract

The microstructure, composition distribution and phase evolution of a high-purity Al-Cu-Mg alloy under homogenization were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and differential scanning calorimeter (DSC). The results show that severe dendritic segregation exists in Al-Cu-Mg alloy ingot. There are a lot of eutectic phases at grain boundary and the primary phases at grain boundary are Al2Cu and Al2CuMg. The primary phases dissolve into the matrix gradually during homogenization with increasing temperature and holding time, which can be described by a constitutive equation in exponential function. The optimum parameter of homogenization is 500°C for 18 h, which is consistent with the result of homogenization kinetic analysis.