Preparation and Characterization of WC-AlCoCrFeNi_2.1 Cemented Carbide

WC based cemented carbide are widely utilized in critical applications such as cutting tools and drilling tools due to their high hardness and wear resistance. However, conventional cemented carbide suffers from inherent limitations in corrosion resistance and high temperature resistance, which greatly restrict their application scenarios. The development of high-performance binders for WC-based alloys represents a crucial technological breakthrough for engineering applications of new-generation advanced cemented carbides. High-entropy alloys, with their compositional diversity, demonstrate potential as binder phases for cemented carbides owing to their capability of achieving superior property combinations. This study employs AlCoCrFeNi_2.1 high-entropy alloy as the binder phase to fabricate WC-AlCoCrFeNi_2.1 cemented carbide via spark plasma sintering. The investigation systematically examines the effects of sintering temperature and binder phase content on the microstructure and mechanical properties of WC-AlCoCrFeNi_2.1 cemented carbide. The inhibition mechanism of AlCoCrFeNi_2.1 binder phase on WC grain growth is elucidated. The main research content and conclusions are as follows.

WC-AlCoCrFeNi_2.1 mixed powders with binder phase contents of 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.% were fabricated by mechanical alloying. The WC-AlCoCrFeNi_2.1 cemented carbide was subjected to spark plasma sintering at different temperatures to investigate the effects of sintering temperature and binder phase content on its mechanical properties and microstructure.

After sintering, XRD results revealed that the cemented carbide primarily consisted of WC and FCC phases. As the sintering temperature increased, the diffraction peak intensity of the WC phase gradually increased while its width decreased. Additionally, higher binder phase content led to stronger FCC phase diffraction peaks in the microstructure. Within the sintering temperature range of 1100 ℃ to 1200 ℃, the relative density of WC-10AlCoCrCuFeNi_2.1 cemented carbide significantly improved from 95.60% to 97.58%. Further temperature increases resulted in negligible density changes. With rising sintering temperature, the grain size of WC-10AlCoCrCuFeNi_2.1 cemented carbide gradually increased; however, excessively high temperatures induced abnormal grain growth As the sintering temperature increases, the hardness of the WC-10AlCoCrCuFeNi_2.1 cemented carbide first rises and then declines, reaching a maximum value of 2264.61 HV₁ at 1200 ℃. The fracture toughness of the carbide decreases with increasing sintering temperature, with the highest value being 10.51 MPa·m^1/2 at 1200 ℃. As the binder phase content increased, the relative density of WC-AlCoCrCuFeNi_2.1 cemented carbide progressively rose from 95.51% (5 wt.%) to 99.76% (20 wt.%), while the grain size gradually decreased. With the increase in binder phase content, the hardness of WC-AlCoCrCuFeNi_2.1 cemented carbide first increases and then decreases, peaking at 2264.6 HV₁ when the binder phase content is 10 wt.%. Before the binder phase reaches 10 wt.%, the hardness is primarily influenced by grain size, increasing as the grain size decreases. When the binder phase exceeds 10 wt.%, the content of the soft and tough phase increases, and its effect outweighs that of grain size, leading to a reduction in hardness. The fracture toughness gradually improves with the increase in binder phase (which acts as the soft and tough phase), reaching a maximum of 12.06 MPa·m^1/2 at a binder phase content of 20 wt.%. The WC-AlCoCrCuFeNi_2.1 cemented carbide exhibits optimal comprehensive mechanical properties at a sintering temperature of 1200 ℃ and a binder phase content of 10 wt.%. Under these conditions, the hardness is 2264.6 HV₁, and the fracture toughness is 10.51 MPa·m^1/2..

Synergistic enhancement of hardness and toughness in WC-HEA composites is achievable by optimizing sintering temperature and binder content. The optimal parameters (1200 ℃, 10% HEA) balance grain refinement, thermal stress mitigation, and phase distribution, providing strong foundation for developing high-performance WC-HEA cemented carbides.