Oxidation of in situ synthesized TiC particle-reinforced titanium matrix composites

The oxidation behavior of TiC particle reinforced titanium matrix composites (TMCs) was studied in a temperature range 550-650 degrees C in atmosphere. The in situ oxidation observation at the very initial stage was investigated by high-temperature optical microscopy in air. The oxide layer of long-term oxidation behavior was examined by scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy unit (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The oxidation kinetics follows a parabolic rate law. The oxidation rate decreases gradually as the oxidation proceeds. The oxidation of the composite took place firstly on Ti because of the higher reactivity of Ti and O-2 than that of TiC and O-2. However, the TiC reinforcement can decrease the overall oxidation rate at 550, 600, and 650 degrees C. It is attributed to the formation of thin and dense oxidation, the enough strong interface cohesion between reinforcements and the titanium matrix alloy. (c) 2005 Elsevier B.V. All rights reserved.