Oxidation and corrosion protection by halide treatment of powder metallurgy Ti and Ti6Al4V alloy

• Simple halide treatment with NH4Cl was carried out on Ti6Al4V alloy.
• High temperature oxidation and electrochemical corrosion were evaluated.
• Improvement in high temperature oxidation resistance was observed.
• Improvement in corrosion resistance was observed for samples treated at 200 °C.

The aim of this work is to study the effect of halide treatment in powder metallurgy Ti–6Al–4V alloy, in order to improve high temperature oxidation and electrochemical corrosion resistance. Halide treatment was performed by immersing samples in a powder mixture containing 3 wt% NH4Cl, at 200 °C and 950 °C. Oxidation resistance was assessed by exposure to 600 °C for 300 h. The microstructure and phase constitution of the formed oxide layers was characterized. Corrosion resistance in aircraft simulated environment was evaluated with electrochemical impedance spectroscopy. Notable improvement in oxidation and corrosion resistance was observed for samples treated at 200 °C.