Microstructural evolution and mechanical characterization of a WC-reinforced CoCrFeNi HEA matrix composite

Prior research has shown that high entropy alloys (HEAs) can exhibit strong combinations of mechanical properties. However, the specific effects of adding ceramic reinforcements to HEAs remain unclear. Established knowledge includes the general understanding of HEA microstructures and their behavior under stress. No prior work had resolved how WC additions influence carbide formation and mechanical performance in HEA matrices. This uncertainty drove the need to explore microstructural evolution and mechanical behavior in WC-reinforced HEA composites. The gap motivated a detailed investigation into phase interactions and property enhancements. Existing studies suggest that carbide phases can improve hardness and strength in alloys. But the exact relationship between WC content and mechanical response in HEA composites remains unexplored. This work aims to address that gap through controlled experimentation and characterization.

The aim of this study is to evaluate how adding WC to a CoCrFeNi HEA matrix affects microstructure and mechanical properties. The specific problem involves understanding the formation of carbide phases and their influence on hardness and strength. The motivation stems from the need to develop materials suitable for high-stress structural applications. The study focuses on the interaction between WC and the HEA matrix during arc melting. It seeks to quantify how WC content affects carbide formation and mechanical outcomes. The researchers propose that WC additions may enhance both strength and ductility in HEA composites. The study also aims to assess the feasibility of using WC as a reinforcement in HEA matrices. By controlling WC content, the researchers hope to identify optimal compositions for structural use.

The study used arc melting under argon to synthesize HEA-WC composites with varying WC content. X-ray diffraction was employed to identify phase changes in the composites. Scanning electron microscopy with energy dispersive spectroscopy analyzed microstructural evolution. The researchers focused on chromium diffusion and carbide formation at the matrix-WC interface. Mechanical properties were evaluated using hardness and yield strength measurements. The study compared base HEA samples with WC-reinforced versions. The process involved controlled additions of WC to the CoCrFeNi matrix. The team used standardized testing protocols to ensure accurate mechanical characterization.

X-ray diffraction revealed the presence of fcc and carbide phases in HEA-WC composites. Scanning electron microscopy showed chromium diffusion from the matrix to WC particles. The amount of alloyed carbide increased with higher WC content in the matrix. The HEA-20wt.% WC sample had a hardness of 593 HV, compared to 180 HV for the base HEA. Yield strength increased from 278 MPa to 1098 MPa with 20 wt.% WC addition. Ductility remained high, with ~50% strain for 10 wt.% WC and ~20% for 20 wt.% WC. The study found a direct correlation between WC content and mechanical performance. These results suggest that WC reinforcement can significantly enhance HEA properties.

The authors state that WC additions to HEA matrices lead to increased hardness and yield strength. They propose that carbide formation at the matrix-WC interface contributes to these improvements. The study suggests that WC-reinforced HEAs may offer excellent mechanical properties for structural use. The researchers note that higher WC content correlates with greater mechanical performance. They observe that ductility remains acceptable even at 20 wt.% WC addition. The findings suggest that WC can act as an effective reinforcement in HEA composites. The authors propose that these composites may provide a balance of strength and ductility. They conclude that WC-reinforced HEAs have potential for demanding structural applications.