Yield strength increase of a CoCrNi medium entropy alloy by interstitial nitrogen doping at maintained ductility

Moravcik, I. and Hadraba, H. and Li, L. and Dlouhy, I. and Raabe, D. and Li, Z.

Volume: 178 Pages: 391-397
DOI: 10.1016/j.scriptamat.2019.12.007
Published: 2020

We show that interstitial nitrogen doping improves the tensile properties of a CoCrNi alloy. A material with 0.5 at% interstitial nitrogen was compared to a nitrogen-free CoCrNi alloy. The nitrogen-doped variant has a stable, single-phase face-centered cubic (FCC) lattice structure without nitrides, also after different annealing treatments (800–900 °C, 10 and 30 min). The nitrogen caused an increase in yield strength by 24–33% at identical ductility compared to the nitrogen-free material with similar grain size. The strengthening effect of nitrogen was explained in terms of the simultaneous increase of the lattice friction stress and of the Hall-Petch coefficient. © 2019

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