Microstructure dependence of grain boundary corrosion in oriented aluminum bicrystals

The dislocation densities of the tilt boundaries were observed and measured on a set of samples of aluminum bicrystals with [110] symmetric tilt boundaries. The variation of the dislocation density with grain boundary misorientation was obtained. It showed that dislocation density increased along with the increment of misorientation and the density minimum emerged at CSL (Coincidence-Site-Lattice) boundaries, which indicated that the atoms of CSL boundary structure have higher mating degree of order. In addition, the corrosion depths of the grain boundaries were measured in the oriented aluminum bicrystals, showing that the corrosion depth was found to increase with grain boundary misorientation of the bicrystals, except at the CSL boundaries where the corrosion depth reduced to a minimum. The variation of dislocation density with misorientation is entirely coincide with that of grain boundary corrosion. The results showed that the microstructure, such as dislocation density, has great contribution to the grain boundary corrosion. It seems to be the microstructure dependence of grain boundary corrosion in oriented aluminum bicrystals.