Nanoscale serration and creep characteristics of Al0.5CoCrCuFeNi high-entropy alloys

Highlights: • Nanoindentation tests were performed in the Al_0.5CoCrCuFeNi HEA RT and 200 °C. • Serrated plastic flow was found at both temperature. • Serrated flow was analyzed by the mean-field theory. • Creep behavior was dominated by the glide-climb mechanism. • The creep simulation was performed based on viscoplastic model. Nanoindentation tests were performed to investigate the nano-scale plastic deformation in the Al_0.5CoCrCuFeNi high entropy alloys at room temperature (RT) and 200 °C, respectively. Serrated plastic flow, manifested as discrete bursts of plasticity on the load-displacement curves, was observed for both temperatures during the loading period, and its behavior and dependence on the temperature was analyzed from the experimental perspective. Creep occurred during the nanoindentation holding period and exhibited very large stress exponent, implying that the dislocation glide-climb is the dominant mechanism. The creep simulations with a two-layer viscoplastic model further revealed that the deformation at a higher temperature (e.g., 200 °C) featured a greater and faster-growing plastic zone underneath the indenter, implying more pronounced dislocation activities.