Enhanced mechanical properties of columnar grained-nanotwinned Cu films on compliant substrate via multilayer scheme

The columnar-grained nanotwinned (cg-nt) Cu films exhibit high strength but low ductility. By introducing the nanocrystalline Cr layers into cg-nt-Cu films forming Cu/Cr nanostructured multilayers, it is found that the number of twins per grain in Cu as well as the twins density decreases with reducing Cu layer thickness, which are analyzed by “growth accident” related twins formation models. The suppression of twin formation via multilayer scheme significantly enhanced the ductility of cg-nt-Cu films without sacrificing their strength.