Surface Analyses of High-Temperature Oxidized In Situ Synthesized Ti-40Al-2.0C Composites

Abstract

With the reaction between titanium (Ti) sponge, high purity aluminum (Al) and TiC/Al inter-alloy, non-consumable arc melting technique has been successfully used in situ synthesize Ti matrix composites of Ti-40Al-2.0C. The composites oxidized at 700~900°C for different time in static air. The influences of oxidation time and temperature to oxidation kinetics of composites were analyzed. The surface morphologies and components of the oxidation scales were examined by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). The results show that the isothermal oxidation kinetic curves of composites mainly follow parabolic rate law. When the composites oxidized at low temperature for short time, the color of oxidation surface is olivine which is similar to the color of the matrix and the oxides exist in non-uniform mixture state of Al2O3and TiO2. While the composites oxidized at high temperature for long time, the color of oxidation surface is deep yellow and the oxides are mainly columnar hexagonal TiO2.