Interstitial solid strengthening is an effective strategy to harden metallic materials, however, it
usually deteriorates the ductility. Here, we report that addition of carbon into the medium-
entropy NiCoCr alloy successfully enhances the strength at no expense of ductility. It was
found that up to 0.75 at.% carbon was completely solid-solutionized in (NiCoCr) 100-x C x
(x= 0, 0.10, 0.25, 0.50 and 0.75 at.%) without formation of any carbides. With the increase of
carbon content from 0 to 0.75 at.%, the yield and fracture strength were increased from 242 …