Nanoindentation into a high-entropy alloy – An atomistic study

The plastic response of a high-entropy alloy is explored by means of simulated nanoindentation tests. We compare nanoindentation into the Cantor alloy – an equi-atomic CoCrFeMnNi fcc solid solution – with that into an elemental Ni fcc single crystal. Using molecular dynamics simulation, strong differences in the plastic behavior are identified. While the total length of the dislocation network in the Cantor alloy is higher than in Ni, the size of the plastic zone is considerably restricted. Dislocations are more localized in the Cantor alloy, both during indentation, but also during retraction of the indenter; emission of prismatic loops is absent in the Cantor alloy. Besides dislocation-mediated plasticity, considerable twinning occurs. No amorphization could be observed. These simulation results are in good qualitative agreement with our current knowledge of plasticity in high entropy alloys.