Dislocation-stacking fault interactions in a nanostructured Al alloy processed by severe plastic deformation

Experimental observations on dislocation-stacking fault (SF) interactions in nanostructured (NS) Al and Al alloys have received very limited attention albeit some available theoretical studies using molecular dynamic simulations in the published scientific literature; consequently, the effect of the SFs on strength and ductility remains poorly understood. In an effort to address this question, the present study reports a type of configurations comprising one or several full dislocation(s) and a SF in a NS Al alloy processed by high-pressure torsion. The configurations were identified and studied using high resolution transmission electron microscopy. The calculations reveal that the two partial dislocations enclosing the SF generate high magnitudes of components of stress in the position of the full dislocation(s), indicative of strong full dislocation-SF interactions. This finding suggests the potential of the SFs to enhance both strength and ductility of NS Al and Al alloys by impeding dislocation slip and entrapping dislocations.