Significant enhancement of the corrosion performance of Ti-6Al-3Nb-2Zr-1Mo alloy via carbon addition in reducing acid environment

•The corrosion behavior of novel Ti-6Al-3Nb-2Zr-1Mo-xC alloys is investigated.•The corrosion resistance is significantly improved by the addition of C.•The C has few impacts on cathodic reaction but vital effects on anodic process.•The addition of C notably alleviates the corrosion of the prior-β grain boundaries.•The α phase acts as the preferential dissolution location compared to β phase.