The influence of Zn addition on microstructure of an Al-1.7 Cu-4.0 Li-0.4 Mg alloy

Abstract

The tensile properties and corrosion behaviours of an ageing Al-1.7 Cu-4.0 Li- 0.4 Mg alloys (in at. %) with or without 0.3 Zn addition were investigated by detailed microstructure evolution using TEM and STEM. Herein, the Zn addition to the Al-1.7 Cu-4.0 Li- 0.4 Mg ageing alloy is determined as a convincing approach to optimising the strength-corrosion resistance balance. With Zn addition, the increasing quantity of T1 phase in grain led to the increase of the tensile property of the Al-1.7 Cu-4.0 Li- 0.4 Mg alloy. While the studied alloy with Zn addition possessed preferable corrosion resistance in respect of intergranular corrosion (IGC) depth reducing. Moreover, the emergence of Zn elements in the coarse phases at grain boundary (GB) may decrease the potential differences between the precipitates at GB and free precipitation zone (PFZ), which could increase corrosion resistance. Keywords: Al-1.7 Cu-4.0 Li- 0.4 Mg alloy, Zn addition, Tensile properties, Corrosion behaviours, Microstructure characteristics, Electrochemical features