Nanoindentation Creep Behavior of Hexagonal Close-Packed High-Entropy Alloys

The effects of maximum load and loading rate on the creep behavior of the single-phase hexagonal close-packed structured GdHoLaTbY alloy at room temperature were investigated by nanoindentation. The hardness, creep depth, creep rate, and stress exponent strongly dependent on the maximum load and loading rate. The creep behavior of the alloy at different maximum loads shows a significant indentation size effect. The creep behavior is dominated by free diffusion at the sample surface at low load retaining loads and by dislocation sliding at high load retaining loads. The creep behavior of the current alloy is greatly sensitive to the indentation loading rate at different loading rates. High loading rates give rise to stress fields with high dislocation density and high strain gradients, which results in a large stress index during the loading retention stage.