Stress corrosion cracking (SCC), liquid metal embrittlement, and corrosion fatigue cracking mechanisms can be evaluated by measuring grain boundary misorientations along the crack path or the crystallography of fracture surface facets. The crystallographic orientation of individual grains can be measured with back Laue, Kikuchi, selected area channelling pattern (SACP), or electron back scatter pattern (EBSP) techniques. EBSPs are unique since a large statistical sampling of individual grains or subgrains as small as a micrometer in diameter can be probed on single large samples.For intergranular fracture, low angle and coincident site boundaries (twins as an example) are typically SCC resistant compared to general high angle grain boundaries. This observation, important for modeling fracture or improving microstructural performance, can be identified by sampling boundaries in the matrix and along the fracture path with EBSP or SACP techniques.Transgranular fatigue mechanisms, dramatically influenced by the test environments for Al-Li-Cu alloys as shown in Figures 1a and b, can be identified my measuring fracture facet crystallographic orientations.
Controllable fatigue cracking mechanisms of copper bicrystals with a coherent twin boundary
