Localized corrosion of friction stir welded Al–Cu–Li alloy: The influence of grain-stored energy on grain boundary micro-chemistry
Yuheng Li, Yuchen Wang, You Lv, Yanyan Li, Bing Liu, Zehua Dong, Xinxin Zhang
Abstract
In the present study, friction stir welding (FSW) was conducted on an Al–Cu–Li alloy, resulting in significant variations of precipitation and grain-stored energy across the weldment, with the highest corrosion susceptibility showing in the thermomechanically affected zone (TMAZ). Localized corrosion in TMAZ initiates in form of intergranular corrosion (IGC) before propagating into grain interiors. Close examination reveals that IGC preferentially attacks boundaries of high misorientations in areas of high stored energies. The dependency of IGC susceptibility on grain boundary misorientation and the peripheral stored energy is associated with the distribution of Cu/Li-rich precipitates and segregations at grain boundaries across TMAZ.