Abstract
The graphene (Gr) can effectively confine the dislocation propagation, allowing for the pronounced strengthening effect. However, due to the technical limitations of atomic resolution, an in-depth understanding regarding the potential strengthening mechanisms at atomic level is still insufficiently comprehended. In this paper, molecular dynamics (MD) simulations were performed to investigate dislocation-Gr interactions and strengthening mechanisms in FeNiCrCoCu high-entropy alloy (HEA)/Gr nanopillars. The hindrance of Gr sheet to mobile dislocations was demonstrated to promote the onset of massive immobile dislocations, especially the Stair-rod dislocation which gave rise to the remarkable strengthening effect. The immobile Hirth, 1/3<110> and 1/6<301> dislocations exerted the subsidiary effect on strengthening the composite pillars. Meanwhile, the diminished dislocation length induced by dislocation reactions and the absorption effect to mobile dislocations was verified to endow a more appreciable dislocation starvation for composite pillars which was conducive to forming more Stair-rod dislocations. In addition, the results also confirmed that the reduction in Gr diameters would directly weaken the pillars attributing to the fact that the Gr edges acted as a dislocation source. These findings may contribute to the design of HEA/Gr composites toward better mechanical properties.
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