Strengthening effect of high-entropy alloys endowed by monolayer graphene

HC Xie and ZC Ma and W Zhang and HW Zhao and LQ Ren, MATERIALS TODAY PHYSICS, 27, 100800 (2022).

DOI: 10.1016/j.mtphys.2022.100800

The graphene (Gr) can effectively confine the dislocation propagation, allowing for the pronounced strength-ening 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, mo-lecular 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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