The initial corrosion behavior of Al–Cu–Li bicrystals: effect of misorientation and precipitates

Al–Cu–Li bicrystals with different misorientation gradients were prepared to study the effect of misorientation and precipitates on the initial corrosion behavior of the Al–Cu–Li alloy by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion testing, and electrochemical testing. The results show that the initial corrosions were generated on the matrix rather than on the grain boundary for the as-quenched alloy. The effect of grain boundary misorientation on the corrosion rates of the as-quenched alloy is very limited. On the other hand, for the aged alloy, the initial corrosions were generated on the grain boundaries, which suffer more severe corrosion than the matrix. Meanwhile, the corrosion of high angle grain boundary (HAGB) is more severe than that of low angle grain boundary (LAGB) for the aged alloy. These results are associated with the high number density of the continuously distributed precipitates on grain boundaries.