Size dependent strength, slip transfer and slip compatibility in nanotwinned silver

Perfect slip transfer through single coherent Sigma 3 twin boundaries is known to be a cross-slip-like mechanism occurring at low stresses, which is expected to strongly depend on material properties like stacking fault energy. In the present study, we extend the argument of perfect slip transfer to (i) multiple closely spaced coherent twin boundaries in a nanotwinned thin film and (ii) to materials with very low stacking fault energy. The slip transfer is indicated by the continuity of slip steps and observed across up to 100 coherent Sigma 3 boundaries. The study addresses size scaling due to multiple weak obstacles for dislocation motion and discusses the underlying deformation mechanisms. The importance of strain compatibility is further extended to incoherent twin boundaries. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd.