High-Temperature Oxidation Behavior of Plasma Surface Nb-Cr-(Si) Alloying System on γ-TiAl

The Nb-Cr-(Si) alloy system has attracted extensive attention from researchers due to its excellent oxidation resistance at high temperature. In this paper, a surface Nb-Cr-(Si) coating was prepared on the γ-TiAl by double glow plasma surface alloying (DGPSA). The oxidation behaviors of Nb-Cr-(Si) coating at 700-900 °C were investigated in detail. The low oxygen permeability of the Cr₂Nb phase improved the oxidation resistance during the initial stage of oxidation. Higher Cr content accelerated the transformation of the non-protective oxide Nb₂O₅ to CrNbO₄ in the oxide scale, avoiding the occurrence of “pesting” and inhibiting the internal diffusion of oxygen. The oxidation growth rate of the Nb-Cr-(Si) coating was only 1/16 that of γ-TiAl after oxidation at 800 °C for 100h. The Nb-Cr-(Si) coating improved the oxidation resistance of γ-TiAl effectively.