ISOTHERMAL AND CYCLIC OXIDATION OF TIAL COMPOSITES

Titanium Aluminide and TiAl matrix composites reinforced with alumina fibers (PRD166) were fabricated by powder metallurgy. During isothermal oxidation at 950 and 1070-degrees-C, composites containing PRD166 fibers exhibited larger weight gains than monolithic TiAl, the composites showed evidence of oxidation along the perimeter of the fibers. A fiber reaction, which was observed after oxidation in air, is believed to result from internal oxidation. The reaction was suppressed by heat treating in vacuum and increasing the aluminum content of the matrix. The oxide adherence on TiAl was improved by the addition of alumina (PRD166) fibers.