INTERMETALLIC DISILICIDES AND TITANIUM ALUMINIDES - A NEW CLASS OF STRUCTURAL HIGH-TEMPERATURE MATERIALS UNDER THE ASPECT OF THEIR HIGH-TEMPERATURE OXIDATION RESISTANCE

The light weight intermetallics TiAl and TiSi2 are interesting materia ls for application in fast moving components like gas turbine blades e tc. at high temperatures. Oxidation behavior is a major issue under th ese conditions and in the paper possibilities are discussed how to imp rove the oxidation resistance in air of these alloys in the temperatur e range 700-900 degrees C for TiAl and 1000-1100 degrees C for TiSi2. In both cases a nitrogen effect exists for air oxidation by which prot ective oxide scale formation is impeded. Suppressing TiN-formation and stimulating the formation of continuous Al2O3 or SiO2 barriers for Ti Al or TiSi2, respectively, by preoxidation in N-free atmospheres or by the chlorine effect are the keys to improved oxidation resistance.