High temperature isothermal oxidation behavior of electron beam melted multi-phase gamma-TiAl alloy

Abstract

The gamma-TiAl alloys fabricated by additive manufacturing have gathered significant attention in recent years due to their unique microstructural features and properties. However, the oxidation kinetics of additively manufactured gamma-TiAl alloys have not been studied thoroughly. Herein, the TNM-B1 alloy was fabricated with the help of electron beam melting (EBM) for the first time and tested for 100 h over a temperature range of 800 degrees C-1000 degrees C; this was aimed at investigating its isothermal oxidation kinetics. Subsequently, the exposed samples were systematically analyzed to study the oxide scales, which was achieved with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Spallation was observed at 900 degrees C and 1000 degrees C after an exposure of 30 h and 5 h, respectively. The results showed that the oxide comprises alternative layers of Al2O3, TiO2, and mixture phases. The oxidation resistance of the EBM-processed TNM-B1 alloy was observed to be superior to those of the conventionally processed TNM-B1 and other gamma-TiAl alloys. Finally, the significance of a fine fully lamellar microstructure on the oxidation kinetics of TNM-B1 alloy was explained.