From abrasive to glaze: evolution of wear mechanisms in TiC-modified CoCrFeMnNi high-entropy alloys from room temperature to 900 °C

Motivated by the imperative for enhanced wear resistance in high-temperature applications such as aerospace, this paper presents a comprehensive investigation into the temperature-dependent wear mechanisms of spark-plasma-sintered CoCrFeMnNi high-entropy alloy (HEA) composites reinforced with titanium carbide (TiC). Five compositions containing 0–50 wt% TiC were evaluated by X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, mechanical testing, and elemental mapping. The 15 wt% TiC composite (H15) exhibited the optimal combination of hardness and compressive yield strength. Ball-on-plate wear tests against Si₃N₄ counterbodies were performed from room temperature (RT) to 900 °C, demonstrating superior wear resistance across this broad temperature range with wear rates of 10⁻⁶ to 10⁻⁵ mm³/Nm. At RT-300 °C, mild abrasive and oxidative wear prevailed, controlled by uniform dispersion of TiC and Cr₇C₃ particles. At 600 °C, a discontinuous oxide-carbide layer forms on the wear surface, while a fine-grained layer develops in the subsurface region. This dual structure effectively suppresses delamination, enabling moderate oxide adhesion to the Si₃N₄ ball while maintaining a low wear rate. At 900 °C, a dense, continuous oxide glaze, comprising Mn-rich and Cr-rich sublayers, acted as a self-lubricating barrier, reducing wear-track dimensions by over 60 % compared to non-TiC HEA and lowering the coefficient of friction. These findings provide the first end-to-end mapping of tribological regimes in TiC reinforced HEAs, offering design guidelines for oxide-glaze engineering in advanced wear-resistant alloys.