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Chromium alloys; Cobalt alloys; Entropy; High-entropy alloys; Iron alloys; Manganese alloys; Reduction, Comprehensive energy; Discharging process; Dislocation mobility; Dislocation motion; Dissolved hydrogen; Hydrogen charging; Hydrogen concentration; Hydrogen reduction, Nanoindentation
Abstract:
The variations in the pop-in behavior of an equiatomic CoCrFeMnNi high-entropy alloy under different hydrogen charging/discharging conditions were characterized via in-situ electrochemical nanoindentation. Results show that hydrogen accumulatively reduces both pop-in load and width, among which the reduction of pop-in width is more noticeable than that of pop-in load. Moreover, the hydrogen reduction effect on both pop-in load and width is reversible when hydrogen is degassed during anodic discharging process. Particularly, the hydrogen-reduced pop-in width was studied in detail by a comprehensive energy balance model. It is quantitatively shown that the dissolved hydrogen enhances lattice friction, leading to an increased resistance to dislocation motion. As a result, fewer dislocations can be generated with a higher hydrogen concentration, causing a smaller pop-in width. This is the first time that the pop-in width indicated dislocation mobility under hydrogen impact is quantitively revealed. © 2021
