Influence of hydrogen on incipient plasticity in CoCrFeMnNi high-entropy alloy

Abstract The influence of hydrogen on the onset of plastic deformation in a CoCrFeMnNi high-entropy alloy (HEA) was examined through the analysis of the load at which first pop-in during spherical nanoindentation experiments occurs on hydrogen-charged and subsequently aged specimens. Results reveal that the dissolved hydrogen lowers the plastic flow resistance, indicated by the shear yield strength, τ y , by modifying defect formation energies. Aging, subsequent to charging, leads to recovery of τ y , but only partially. The results are discussed in terms of the vacancy-mediated dislocation nucleation, which is supported by the estimated activation volume for deformation.