Investigation of isothermal oxidation performance of TiAl alloys sintered by different processing methods

Abstract

The production of TiAl alloys can be a discouraging task owing to their low ductility at room temperature. However, the development of novel methods that are alternative to traditional methods for producing TiAl alloys is a fundamental aspect for structural applications in the automotive and aerospace industries. Resistance sintering method enables the production of TiAl alloys, thanks to a combination of remarkable attributes such as shorter sintering time, fast heating rates. This method is promising under circumstances where the rapid densification, short sintering time and low cost becomes a great advantage. The objective of the following work was to compare the isothermal oxidation performance of TiAl alloys produced by resistance sintering (RS) and pressureless sintering (PS) methods. After oxidation at 900 °C for 200 h, the final weight change of RSed alloy (6.36 mg/cm2) was lower than that of PSed alloy (8.92 mg/cm2). X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were performed to characterize the oxidized alloys. Analyses results show that the oxidation products were TiO2 and Al2O3 oxides, the oxide scale of both alloys are composed a multilayered structure. The relatively continuous Al2O3 layer formed on the scale of RSed alloy played a major role in enhancing the oxidation resistance of the alloy.