Investigation of the surface characteristics of WC–Co structures under Local E-beam irradiation via experiments and molecular dynamics simulations

Abstract

We investigated the atomic structural variations on the free surface of tungsten carbide-cobalt (WC–Co) through both experiments and molecular dynamics simulations under electron beam (e-beam) irradiation. Initially, e-beam experiments were conducted to compare cobalt dissociation and elucidate its physical implications. Subsequently, molecular dynamics simulations qualitatively reproduced the evaporation phenomena that occurred over the free surfaces of the five WC–Co structures. The nano-polycrystalline structure and configurations featuring a small cobalt (Co) surface exhibited a comparatively low number of escaped Co atoms, attributed to their relatively high area/perimeter ratio. This study subsequently investigated the impact of e-beam treatment on the randomness of atomic arrangements and mechanical properties by assessing variations in local entropy and von Mises stress distributions at different positions and in different simulation states. Position-dependent von Mises stress, interatomic potential, and local entropy profiles, reproduced profiles with the same dataset, and two-dimensional colored maps at various simulation states were generated to illustrate individual variations and correlations between local entropy and von Mises stress to demonstrate instability of atomic structures. Our study demonstrated that e-beam treatment influenced the atomic structural instability and mechanical characteristics quantitatively.