Microstructure, mechanical properties and oxidation behavior of the TiAl(Si,Ag) coating on near-α titanium alloy

In order to improve oxidation resistance of TIMETAL834, protective coating based on γ-TiAl intermetallic alloy with Si and Ag admixtures was produced by magnetron sputtering. Analytical scanning and transmission electron microscopy were used for detailed analyses of a microstructure and chemical composition of the coating. It was found that the coating contains two sublayers with different microstructure and morphology. Energy-dispersive synchrotron radiation diffraction was applied for stress analysis. The results show that there are tensile residual stresses present within the TIMETAL834 substrate and compressive residual stresses within the γ-TiAl sublayer. It was established that the surface treatment applied in this work essentially improves the alloy oxidation resistance.