The Oxidation Behaviour of TiC Matrix Ni{sub}3Al and Fe40Al Toughened Composites at High Temperatures

摘要

High temperature oxidation of TiC ceramic matrix Fe40Al and Ni{sub}3Al toughened composites (Fe40Al/TiC, Ni{sub}3Al/TiC) of different TiC contents, made by pressureless melt infiltration, was investigated. Oxidation experiments were conducted in air for up to 65 hours at 700-1100°C. Weight gains of the composites showed that Fe40Al/TiC is more oxidation resistant than Ni{sub}3Al/TiC ones. SEM/EDS and X-ray diffraction showed that the dense oxidation layers of the two types of composites are mainly composed of crystalline TiO{sub}2. The growth of the oxidation layer follows parabolic passive oxidation kinetics, the calculated values of the activation energy of the oxidation mechanism being 270-280kJ.mol{sup}(-1) and 240-250kJ.mol{sup}(-1) for Fe40Al/TiC and Ni{sub}3Al/TiC, respectively. Al{sub}2O{sub}3 and Ni-rich phases were also detected in the oxidation layer of Fe40Al/TiC and Ni{sub}3Al/TiC, respectively.