Effects of Homogenization Temperature on Microstructure of 2A66 Al-Cu-Li Alloy

Abstract

The microstructure evolution during homogenization of 2A66 Al-Cu-Li alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). The results showed that the dendritic segregation can be found in the ingot of experimental alloy. Numerous eutectic phases can be observed in the grain boundary, and the distribution of the main elements along the interdendritic region varied asymmetrically. It was found that the main secondary phase was Al2Cu. Differential scanning calorimeter (DSC) results showed that the over-burnt temperature of 2A66 Al-Cu-Li alloy was 515°C. With the increase of homogenization temperature in the area of 480°C~510°C, the boundaries of experimental alloy became sharp and the most of secondary phase dissolved into the matrix. The experimental alloy heat treated at 520°C was over-burnt. The Al3Zr precipitated and α (Al) super-lattice was observed by TEM in the experimental alloy after homogenization.