Development and characterization of CoCrFeNi high entropy alloy composites reinforced by B4C ceramic particles

Abstract

To address the challenge of the low yield strength of single-phase FCC high-entropy alloys (HEAs), developing high-performance HEA composites has emerged as a promising strategy for enhancing the mechanical properties of HEAs. In this study, we propose a novel CoCrFeNi-based HEA composites incorporating a small amount of B₄C ceramic particles. The influence of varying B₄C ceramic particle content on the microstructure evolution and mechanical properties of CoCrFeNi(B₄C)_x HEAs was systematically investigated. Microstructure analysis reveals that increasing the B₄C ceramic particles promoted the precipitation of M₇C₃ carbides at grain boundaries, resulting in a dendritic microstructure. Mechanical testing demonstrated a significant improvement in yield strength and Vickers hardness, attributed to the synergistic strengthening of solution and precipitation strengthening. Furthermore, the microhardness of the M₇C₃ carbides increased from 12.1 GPa to 15.5 GPa with higher B₄C ceramic particle content, highlighting the contribution of these carbides to the overall hardness of the composite. This design strategy exploits the synergy between the metal matrix and ceramic reinforcements, improving mechanical performance and offering new possibilities for the development of advanced materials for demanding industrial applications.