The influence of precipitates on the indentation creep behavior of (CoCrFeNi)₉₄Ti₂Al₄ alloy

This study investigates the influence of precipitate size on the room-temperature indentation creep behavior of (CoCrFeNi)₉₄Ti₂Al₄ high-entropy alloy by using nanoindentation system equipped with Berkovich diamond indenter combined with microstructural characterization. Nano-hardness, creep displacement, and creep strain rate of specimens with different sizes of nanoscale precipitates were analyzed under conditions of a 20 mN peak load and a 0.5 mN/s loading rate. Results show that precipitate refinement enhances the alloy hardness and reduces the total creep depth, while the steady-state creep rate increases slightly with an insignificant increment. When the testing conditions (loading rate and peak load) were changed, although the trend of inhibiting total creep displacement by precipitate refinement remained unchanged, the effect of precipitate refinement on the steady-state creep rate was not significant. Additionally, creep analysis using a spherical indenter were conducted to calculate the creep stress exponent n . Results showed that the precipitate-containing alloy exhibited a higher n value than the precipitate-free alloy, with dislocation creep identified as the dominant deformation mechanism in both cases. This study enables rapid screening of materials via nanoindentation creep, provides deeper mechanistic insights into the creep deformation of precipitation-strengthened high-entropy alloys, and establishes a theoretical framework for property optimization.