Oxidation kinetics of Ti6Al4V alloy deposited by wire arc additive manufacturing using argon gas as processing atmosphere

Ti6Al4V alloy is currently the most common metal alloy of the α+β phase type, its application is increasing as it has excellent properties at elevated temperatures. The main users of Ti6Al4V alloy are industries like of aerospace, naval, and biomedical; therefore, Ti6Al4V alloys one of the most studied material worldwide. One of the great advantages that Ti6Al4V alloy offers is the possibility of manufacturing components in situ by means of additive technologies.. Similar studies, in additive manufacturing, have reported the formation of titanium oxide on the surface of the material, followed by an oxygen-enriched region called "α-case". By means of thermogravimetric analysis, the oxidation effect on the surface of Ti6Al4V samples, obtained by wire arc additive manufacturing as well as samples from conventional manufacture, were studied. Argon gas, with an oxygen partial pressure of 1x10-5 atm, was used as the oxidation atmosphere within a range of 550°C to 950°C and oxidatión times of 60 min and 180 min. For the oxidation reaction, the kinetic analyses led to calculate the activation energy as 250 kJ/mol and 166 kJ/mol for the Ti6Al4V alloy processed by conventinal and additive manufacturing, respectively. The results of the of thermogravimetric analysis were fitted to a parabolic-type kinetic model. Furthemore, a mathematical model was proposed to predict the oxidation kinetics. The experimental data were fitted to the mathematical model in the range of 750 - 950°C for Ti6Al4V alloy by wire arc additive manufacturing. The oxidized microstructures were analized by optical and electronic microscopy finding α-case on the surface of the samples.