Corrosion Resistance of Titanium Aluminide Layers on Two Phase (α+β) Ti6Al4V Titanium Alloy

The paper presents results of investigations into the structure and corrosion resistance of Ti-Al diffusion layers produced on two phase (a+b) Ti6Al4V alloy by Chemical Vapour Deposition (CVD). The process was carried out in aluminium chloride (AlCl3) mixed with argon atmosphere. Surface topography and microstructure characterization of the coatings were examined by scanning electron microscopy (SEM). The local chemical composition witch 1 μm lateral resolution was measured via EDS. The phase content was investigated by X-ray diffraction and analysis of the chemical composition of the surface by XPS. Corrosion resistance was tested using the potentiodynamic method in 0.1M Na2SO4 and 0.1M H2SO4 solutions at the room temperature. Their resistance to high temperature at atmospheric pressure was tested by 24-hours cycling to 700°C. The results indicate that the layers produced on the Ti6Al4V titanium alloy exhibit a very good adhesion combined with exceptional corrosion resistance, especially high at high temperatures.