Remarkable wear resistance in ceramic-metal composites with composition gradients and regionalized heterostructures

Ceramic–metal composites undergo a predominant mode of wear failure known as brittle intergranular fracture caused by strain localization. In this work, we report for the first time the employment of heterostructures to alter the failure mode of frictional interfaces within such composites. We achieve this by integrating fine-grained tungsten carbide (WC)/graphene nanoplates (GNPs) into the surface layer of coarse-grained WC–11 wt%Co cemented carbides, constructing a gradient heterostructure that simultaneously possessed fine-grained, binder phase, GNPs composition gradients, and regionalized heterostructure of coarse and fine grains. This structure yielded extraordinary wear resistance, outperforming gradient-structured cemented carbides and decreasing the wear rate of the WC-11 wt% Co cemented carbides surface by an order of magnitude. The multi-typed gradient structure improved the resistance of the composite to frictional loads along with fracture resistance. During dry sliding, the heterostructure facilitated strain hardening and transfer by activating dislocations and stacking fault networks. Moreover, the pilling ups of high-density geometrically necessary dislocations of types $\left(a\right)$, $\left(c\right)$, and $\left(a+c\right)$ within the constrained coarse-grained WC increased the strain tolerance and promoted plastic deformation uniformity. This synergistic effect enabled the frictional interface to accommodate elastoplastic deformation induced by frictional stresses, thereby preventing localized brittle fractures. The proposed approach paves a novel pathway for designing wear-resistant ceramic–metal composites.