Influence of carburization on oxidation behavior of High Nb contained TiAl alloy

• Solid carburization treatment was applied to Ti–45Al–7Nb–0.3W alloy.
• The carburization layer consisted of nano-structured carbide phases.
• Oxidation resistance was significantly improved by carburization.

In this work, surface carburization has been performed on Ti–45Al–7Nb–0.3W alloy. The isothermal oxidation behavior of the alloy has been investigated in static air at 950 °C for 100 h. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied to study the microstructural evolution. The results reveal that the carburized layer, with a thickness of 7.4 μm, is composed of nano-structured Ti2AlC and Ti3AlC phases. The oxidation weight gain of the carburized TiAl is half of that of the bare TiAl. The oxide scale of the carburized TiAl is compact without delamination and spallation. The inward diffusion of oxygen atom was hindered due to the existence of the carburized layer. Therefore, the carburization process is an effective and feasible treatment to improve the oxidation resistance of high Nb contained TiAl alloys.