The hardness–toughness trade-off relationship is an essential challenge when creating high-performance WC–Co hardmetals. In this work, by combining plasma milling and low-pressure sintering, a dual-scale plate-like WC–8Co hardmetal is fabricated. The hardmetal simultaneously exhibits ultra-high strength (1701 kgf/mm²) and fracture toughness (21.77 MPa*m^1/2), with bimodal grain size distributions of plate-like WC with average diameter of 1.1 μm and 1.4 μm, respectively. This breaks the normal trade-off relationship between the strength and the fracture toughness, which is because of the enhancement of crack propagation resistance owing to the synergetic effect of the plate-like WC and the bimodal grain structure. Existing models for hardness and fracture toughness prediction are invalid for WC–Co hardmetals with oriented plate-like WC grains. Modified models, based on the Lee-Gurland hardness model and the Ravichandran fracture toughness model, are developed by inducing factors R, which is the proportion of the WC(0001) plane in the indented plane, and can be determined by XRD analysis, to represent morphology features of WC. The modified models are universal and can reliably predict the hardness and fracture toughness of WC–Co hardmetals with both equiaxial and plate-like WC grains.

在制造高性能 WC-Co 硬质合金时，硬度-韧性权衡关系是一项基本挑战。在这项工作中，通过结合等离子铣削和低压烧结，制造了一种双尺度板状 WC-8Co 硬质合金。硬质合金同时表现出超高强度（1701 kgf/mm ²）和断裂韧性（21.77 MPa*m ^1/2)，具有平均直径分别为 1.1 μm 和 1.4 μm 的板状 WC 的双峰粒度分布。这打破了强度和断裂韧性之间正常的权衡关系，这是因为板状WC和双峰晶粒结构的协同作用提高了裂纹扩展阻力。现有的硬度和断裂韧性预测模型对具有取向板状 WC 晶粒的 WC-Co 硬质合金无效。修正模型，基于 Lee-Gurland 硬度模型和 Ravichandran 断裂韧性模型，通过引入因素 R（即 WC(0001) 平面在压痕平面中的比例）开发，并且可以通过 XRD 分析确定，以代表WC的形态特征。