High-Temperature Oxidation of Double-Glow Plasma Tantalum Alloying on γ-TiAl

A Ta-modified layer was prepared on γ-TiAl by double-glow plasma surface metallurgy technique. Based on the results of high-temperature oxidation tests at 700, 800, and 900 °C, we studied the morphology, depth profile, and phase of γ-TiAl and Ta-modified layer by scanning electron microscopy, energy spectrum analysis, and X-ray diffraction analysis. Results showed that the Ta-modified layer was tightly bonded to the substrate without voids and cracks, consisting of the α-Ta outer layer and inner diffusion layer. It was found that the isothermal oxidation kinetic curves of the TiAl with the Ta-modified layer followed the parabolic rate law. Ta element promoted the diffusion of Al and formation of uniformly mixed Al2O3/Ta2O5 films, which prevented the inward diffusion of oxygen and help to the improved high-temperature oxidation resistance.