Enhancement of wear resistance in Mo-based composites through moderate addition of (Hf0.25Ta0.25Nb0.25Ti0.25)C high entropy ceramics

Abstract

Abstract

Molybdenum alloys offer excellent high-temperature properties but suffer from poor wear resistance, which limits their use in severe friction and high-load environments. In this study, different concentrations of (Hf 0.25 Ta 0.25 Nb 0.25 Ti 0.25 )C High entropy carbides (HECs) were doped into the pure molybdenum (Mo), and their wear resistance was investigated and compared with pure Mo under different loads, utilizing XRD, SEM, TEM, EBSD, surface hardness testing, and surface profilometry for comprehensive characterization. Surprisingly, at a load of 30 N and 40 N, the 3% HECs doped sample exhibits a lower wear rate of 0.75 × 10 -7 mm 3 /N·m and 1.37 × 10 -7 mm 3 /N·m, which reduced by 52.8% and 28% compared to pure Mo samples. However, when the load increases to 50 N, the wear resistance of HECs doped samples is even worse than that of pure Mo sample. The superior wear resistance under low loads is attributed to the dispersion strengthening effect induced by HECs doping, which enhances the surface hardness and increases the dislocation density. In contrast, the deterioration in wear resistance under high loads is attributed to the detachment and fragmentation of ceramic particles, which transition from reinforcing agents to abrasive third-body wear particles, thereby accelerating material removal. The strategy proposed herein holds substantial promise for enhancing the wear resistance of molybdenum and its alloys.