The Mechanical Properties and Microstructure of Nanostructured Cu with a Flexible Random Distribution of Multimodal Grain Size Prepared by a Combination of Electrodeposition and Recrystallization Annealing

A bulk nanostructured (NS) Cu with a flexible random distribution of multimodal grain size ranging from 1.12 μm to 30 nm was fabricated here by annealing a pre-designed heterogeneous layered structure Cu template fabricated by electrodeposition where the small grains with average grain size of about 40 nm and a large grain size with near micron scale distribute alternately according to the layer thickness ratio of about 4:1 along the deposition direction. Such a heterogeneous NS Cu exhibits a remarkable large strain hardening ability in tensile deformation, which results in a superior combination of high ductility of elongation to failure of near 40% and moderated strength of yield strength of about 470 MPa. Several strengthening effects brought by such a heterostructure, including producing more effective dislocation activity, the inhibition of local plastic flow and the release of local stress concentration, have been suggested to contribute to a more durable strain hardening ability and excellent mechanical properties of NS Cu. In addition, the morphology of fracture and deformation surface is captured to analyze the difference in the mechanical behavior of the NS Cu with random distribution of multimodal grain size by comparing with other structure Cu.