Analysis of High Temperature Oxidation Process and Mechanism of Heterogeneous Titanium Alloy

This study explores the differences in oxidation color, oxidation products, and high-temperature oxidation resistance between TA1 and Ti-6Al-4V (TC4) titanium alloys following a 50 h oxidation treatment at 450 °C and 750 °C. A combination of analytical techniques—optical microscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and micro-Vickers hardness testing—was employed to characterize the morphology of the oxide layers, elemental distribution, phase composition, and microhardness variations. The results reveal that at 450 °C, both alloys develop relatively compact oxide films. TA1 exhibits a yellow–gray coloration, while TC4 displays a characteristic blue–violet interwoven color. At 750 °C, however, the oxide layers become porous and prone to spallation, with a brown appearance and predominance of TiO2. XPS analysis confirms that Ti4+ (TiO2) is the dominant oxidation state on both alloy surfaces at 750 °C, with TC4 showing a significantly higher content of Al2O3. Microhardness measurements indicate that high-temperature oxidation increases the hardness of both alloys, with TC4 consistently exhibiting higher hardness than TA1. TC4 demonstrates superior oxidation resistance: at 450 °C, it forms a denser oxide layer with lower oxygen uptake, while at 750 °C, its oxide layer thickens more significantly, likely due to increased brittleness and spallation. This study underscores the profound impact of high-temperature oxidation on the microstructure and mechanical properties of titanium alloys and highlights the critical role of oxide layer density and stability in determining oxidation resistance. These findings provide valuable insights for the application of TA1 and Ti-6Al-4V alloys in high-temperature environments.