Deformation induced grain boundaries in commercially pure aluminium

Abstract The structure of commercially pure aluminium processed by equal channel angular extrusion at room temperature, to an equivalent strain up to 8, was studied by transmission electron microscopy. Attention was paid to the structure evolution of the generated boundaries. Three types of boundaries were found, namely polygonized dislocation wall, partially transformed boundary, and grain boundary. By increasing strain, polygonized dislocation walls transform firstly into partially transformed boundaries, then into grain boundaries. Dissociation of lattice dislocations is suggested to cause the transformation to occur. At equivalent strain equal to 8, most of the generated boundaries transform into grain boundaries.