Recent experimental evidence has shown that even face-centered cubic materials that were not normally associated with deformation twinning, such as Al, would twin given a sufficiently high stress concentration such as at a crack tip. A computational study was made here of the atomic structures that formed at the tips of atomically sharp cracks in Al single crystals under loading. The simulations were carried out by using the quasi-continuum method; a mixed continuum and atomistic approach. A variety of loading modes and orientations were examined. It was found that for certain combinations of loading mode and orientation, deformation twinning did occur at Al crack tips in agreement with experimental observation. For other configurations, either dislocation emission or in one case the formation of an intrinsic–extrinsic fault pair was observed. It was also found that the response at the crack tip could depend on the crack-tip morphology in addition to the applied loading and crystallographic orientation.

Deformation Twinning at Aluminum Crack Tips. S.Hai, E.B.Tadmor: Acta Materialia, 2003, 51[1], 117-31