Atom scale study of cracks in the carbide phase of WC–Co alloys

Abstract

ABSTRACT In this study, cracks propagating in WC grains are investigated at the atom scale along the [0001] axis. A brittle crack, characterised by cleavage along {1, 0, −1, 0} prismatic facets and the absence of dislocations is observed. The crack follows a zig-zag path allowing a higher deformation energy to be absorbed by the crystal. A ductile crack is also characterised. The plastic zone is limited and contains mainly multipoles consisting in unextended dislocations. The crack path is tortuous and delineated by dislocation arrangements sometimes involving extended dislocations. Close to the crack tip, the fracture is discontinuous and nanocracks occur at the level of dislocation arrangements. These dislocation configurations could provide crack nucleation sites for the crack propagation.