1991 Volume 32 Issue 10 Pages 885-897
Misorientation-dependent intergranular stress-corrosion-cracking (SCC) in a series of alpha Cu–Al alloy bicrystals is reviewed, with the focus on the authors’ work. The research programme employing precisely oriented bicrystals would lend much to the understanding of intergranular SCC depending on the structure and energy of a grain boundary.
The susceptibilities of the symmetrical tilt and twist boundaries to SCC are strongly dependent upon the misorientations. Susceptibility minima are present at several angles which yield a relatively higher planar density of coincidence-site lattice points at the boundaries. Grain-boundary energy cusps have been often observed at these angles in some face-centred cubic metals in the literature.
A stress field generated as a result of the interaction between lattice dislocations and a grain boundary may reduce the SCC resistance of the boundary. It becomes evident that the susceptibility is suddenly decreased as the misorientation decreases from approximately 20° to 15°. This is highly likely due to the increase of dislocations which do not interact with a grain boundary and can pass through the boundary.
It can be said that the observed variation in the susceptibility to intergranular SCC with misorientation is mainly correlated with the boundary structure, energy, and the dislocation behaviour at the boundary.
