Non-isothermal oxidation and ignition prediction of Ti-Cr alloys
(1. National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084, China;
2. Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys,
Beijing Institute of Aeronautical Materials, Beijing 100095, China)
2. Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys,
Beijing Institute of Aeronautical Materials, Beijing 100095, China)
Abstract: The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influencing mechanism of chromium on the oxidation resistance of Ti-Cr alloys was discussed. The results show that the oxidation resistance of the alloys decreases with Cr below a critical chromium content wC and increases above wC; above 1000 K, the oxidation kinetics obeys parabolic rule and titanium dominates the oxidation process; after oxidation, the oxygen-diffusing layer is present in the alloy matrix, the oxide scale is mainly composed of rutile whose internal layer is rich in chromium, and chromium oxides separated out from TiO2 near the alloy-oxide interface improve the oxidation resistance. Ignition of metals and alloys is a fast non-isothermal oxidation process and the oxidation mechanism of Ti-Cr alloys during ignition is predicted.
Key words: Ti-Cr alloy; non-isothermal oxidation; thermogravimetric analysis (TGA); oxide scale microstructure; ignition