INFLUENCE OF MINOR ELEMENTS ON OXIDATION BEHAVIOR OF TIAL INTERMETALLIC COMPOUND

The influence of chlorine, sodium and oxygen in TiAl on oxidation beha vior has been studied by using reactive-sintered Ti-33.5 mass%Al-2.5 m ass%Mn made from various raw powders. As the chlorine content in react ive-sintered TiAl-Mn increases, the mass gain after the oxidation test at 1223 K for 86.4 ks decreases. The TiAl-Mn containing more than 500 ppm chlorine has excellent oxidation resistance owing to the protecti ve Al2O3 film formed on the surface at an early stage of oxidation. Ch lorine in the TiAl-Mn exists as NaCl particles which are introduced fr om the Ti powder produced by the Hunter method. Moreover, halogen such as fluorine and bromine has been found to improve the oxidation resis tance of TiAl-Mn.