Untitled

Abstract

Alloying based on Al-Li alloys plays an important factor for an adjustment of microstructure as well as corrosion behavior. In this study, we mainly focus on microstructural evolution of Al-4.5Cu-1Li-0.4Mg-0.4Ag-0.4Mn-0.5Zn alloy during homogenization and aging treatment. Microstructure and composition of the homogenized alloys and aged alloys were investigated. The homogenized alloys were mainly composed of Al(α), Al 7 Cu 4 Li, Al 3 Li and Al 2 CuLi precipitates. All precipitates coarsened with increase of homogenization temperature and holding time. Peak-age could realize when the homogenized and solution-treated alloy was aged at 120 °C for 4 hours and then 180 °C for 10 hours. The peak-age alloy was mainly composed of Al 2 CuLi, Al 20 Cu 2 Mn3 and Cu-rich precipitates. In the 0.5% NaCl solution, corrosion potential and corrosion current density of the peak-age alloy were -573 mV and 1.028 μA/cm 2 , respectively. And the overage alloy had more positive current potential of -557 mV and higher corrosion density of 4.487 μA/cm 2 . In the 3.5% NaCl solution, Tafel polarization of the peak-age alloy revealed the corrosion potential and corrosion current density to be -611 mV and 2.005 μA/cm 2 , respectively. The over-age alloy had more negative corrosion potential of -653 mV.