Formation of Σ3{110} incoherent twin boundaries through geometrically necessary boundaries in an Al-8Zn alloy subjected to one pass of equal channel angular pressing

Abstract

For coarse grained (CG) alloys with high stacking fault energies (SFEs), like aluminum, deformation twins can rarely form. Here, we report that Σ3{110} incoherent twin boundaries (ITBs) could be generated in a CG Al-8Zn alloy by one pass of ECAP. A systematic investigation shows that the Σ3{110} ITBs are formed by gradual evolution from geometrically necessary boundaries (GNBs) delineating deformation bands (DBs) by lattice rotation via <111>-twist CSL boundaries. This is a new deformation mechanism in Al alloys, which has never been reported.