Ta-alloying for the construction of fully eutectic structure to enhance the broad-temperature tribological performance of CoCrFeNi high-entropy alloy: A systematic study on compositional and structural evolutions

The CoCrFeNi-based high-entropy alloys (HEAs) often suffer from significant wear at high temperatures due to their low strength and thermal softening behavior. Introducing an eutectic structure into the alloy is an effective strategy to address above problem. However, the wear mechanisms associated with the evolution of structure/temperature are not yet well understood. In this work, a CoCrFeNiTa_0.4 alloy was fabricated using arc melting based on the design of a eutectic structure. The excellent resistance to softening of the eutectic structure imparts to the alloy enhanced wear resistance across a broad temperature range. Particularly at 800 °C, the synergistic effect of the dense oxide layer and the eutectic structure in reducing friction and wear results in a wear rate as low as (1.6±0.10)×10^-6 mm³·N^-1·m^-1. The structural and chemical evolution of the alloys during high-temperature friction processes was systematically investigated, and the results drawn provide certain insights for the design of high-temperature wear-resistant CoCrFeNi series alloys.