Enhanced high-temperature oxidation resistance of additively manufactured CoCrNi medium-entropy alloy via in-situ alloying with nitrogen

Enhancing the oxidation resistance of additively manufactured alloys is critical for high-temperature applications. Here, we show that nitrogen doping significantly improves the oxidation performance of a selective laser melted CoCrNi medium-entropy alloy at 1000 °C. Through detailed kinetic analysis and microstructural characterization, we elucidate a diffusion-controlled mechanism by which interstitial nitrogen governs oxidation behavior. The nitrogen-doped alloy exhibits a thinner oxide scale, suppressed formation of spinel phases, a denser oxide structure, and a more stable interface with smoother elemental gradients. This work establishes interstitial nitrogen doping as an effective strategy for engineering oxidation-resistant alloys.