Atomic-scale investigation of the mechanical properties of WC grains and interfaces in cemented carbide WC-Co

High demands are imposed on the surface quality of machined WC-Co and binderless WC. An in-depth comprehension of microstructures should be enhanced, as their behaviors determine the quality of the ultimate machined surface. In this paper, the mechanical properties of WC are acquired through nanoindentation, and the mechanical properties of its typical crystallographic planes are acquired via molecular dynamics indentation simulation. The underlying deformation mechanisms are elucidated. Representative interfaces, including grain boundary (GB) and phase boundary (PB) models, are constructed. The corresponding GB energy and shear strength are obtained and compared. Firstly, it has been found that the plastic deformation on both typical crystallographic planes of WC crystals is primarily mediated by slip systems involving the {101¯0} planes and < 112¯0 > direction, where dislocations and stacking faults nucleate and propagate. The indentation simulation can provide complementary perspectives to nanoindentation technology at smaller scales. Then, it is found that the shear strength of the GBs mainly depend on the crystallographic alignment across the GB and the density of covalent bonds formed. The shear strength of the WC/Co PBs is still considerably lower than that of most WC/WC GBs. The details revealed in this study can contribute to the work of experts in material design, material synthesis and mechanical processing.