The density functional theory and pseudopotential method are used to study mechanical properties of nanoscale cobalt binder layers epitaxially crystallized between WC(100) surfaces. It has been shown that the tensile strength of an epitaxial cobalt binder layer is twice larger than that of single crystal, but the shear module is six times less. The hardness of an epitaxial cobalt binder layer can significantly exceed the hardness of bulk cobalt.