Titanium Aluminide and TiAl matrix composites reinforced with alumina fibers (PRD166) were fabricated by powder metallurgy. During isothermal oxidation at 950 and 1070 OC, composites containing PRD166 fibers exhibited larger weight gains than monolithic TiAI; the composites showed evidence of oxidation along the perimeter of the fibers. A fiber reaction, which was observed after oxidation in ai...

Diffusion couples of pure Ti and polysynthetically twinned (PST) TiAl (49.3 at.% Al) were prepared by high vacuum hot-pressing, with the bonding interface perpendicular to the lamellar planes. Diffusion experiments were carried out by annealing the couples in the same furnace at 650, 700 and 850oC for various times. The cross-section of the couple was studied using scanning electron microscopy ...

The low temperature deformation microstructure of TiAl is dominated by the presence of stacking fault dipoles [I]. Two different faulted dipole geometries have been proposed in the literature [2,3], and the existence of both types of faulted dipoles have been verified in the present study with comparisons to computer simulated images. These comparisons suggest that extrinsic stacking faults in ...

Gamma titanium aluminide (γ-TiAl) is considered a high-performance, low-density replacement for nickel-based superalloys in the aerospace industry due to its high specific strength, which retained at temperatures above 800 °C. However, low damage tolerance, i.e., brittle material behavior with propensity rapid crack propagation, has limited application of γ-TiAl. Any cracks introduced during ma...

Abstract In their temperature window of application, TiAl alloys typically fail in a semi-brittle manner. For this material class, the Griffith concept, developed initially for ideal brittle materials, has to be adapted by additional dissipative contributions fracture resistance: plastic deformation, crack bridging, work deform and shear ledges, bifurcation. These terms resistance induce pronou...

The oxidation resistant light weight aluminides: NiAl and TiAl with ordered