Kinetics of Oxidation of Binary Ti-Cu Alloys in the 600–800 °C Temperature Range

The oxidation behaviour of Ti alloys is a crucial aspect for structural components operating at high service temperature. The aim of this study is to identify the oxidation kinetics and mechanism of binary Ti-Cu alloys with a progressively higher amount of Cu with the alloys having a α + β lamellar structure. It is found that all the alloys followed a non-ideal (i.e., n ≠ 2) parabolic relationship, as controlled by anionic oxygen diffusion, with a distinct effect from both oxidation temperature and alloy chemistry. Specifically, faster oxidation kinetics are found both at higher temperatures and for higher Cu contents, resulting in the formation of thicker oxide scale layers. The oxidation mechanism primarily entails the formation of the stable TiO2 rutile polymorph. However, transitions through metastable phases (e.g., anatase) and texturing of rutile are also revealed as dictated by the composition of the alloy at specific oxidation temperature/time pairs.