Abstract
The most important requirements for a structural material are high strength, ductility, and crack resistance. It is well known that strength of most crystalline materials can be drastically improved by scaling down their microstructural elements (i.e. crystal grains) to the nanoscale. Unfortunately, it often makes the materials signi?cantly less ductile and less crack resistant. One of a few classes of materials exhibiting less ductility drop is a group of metal-metal multilayered composites with a sub-100nm layer thickness (metal-metal nanolaminates). It is known that strength and plasticity of such nanolaminates can be improved if their layers can easily slide (shear) at the interface. However, the role of the interface shear during crack propagation in the nanolaminates is not well understood.This research aims to reveal whether the interface shear is bene?cial to crack resistance of the nanolaminates and understand the interplay between the interface shear e?ects and other microstructural factors in?uencing the fracture in Cu/Nb nanolaminates, which are the most studied among nanolaminates exhibiting interface shear. Engineering the interface is especially attractive in this class of nanomaterials as their interfaces can be rather easily engineered (via known fabrication methodologies or other defect engineering means) to achieve certain mechanical performances of the materials.The results reveal that low interface shear strength can be utilized to improve fracture resistance in the studied nanolaminates, though weak grain boundaries can suppress the interface shear and the associated crack resistance improvement. This knowledge can be used to further optimize the nanolaminate fabrication process and achieve a good strength, ductility, and crack resistance at the same time.