Microstructurally Tailored High Temperature Metal Matrix Composites for Advanced Turbines

Successful development of advanced turbine engines will depend heavily upon rapid development of new, reliable, lightweight metal matrix composites (MMC's) having unprecedented high temperature properties. Recent developments in the manufacture of MMC's by vapor deposition methods offer the prospect of producing polyphase microcomposite precursors in the form of continuous monofilaments or thin monotapes. In these continuous processes, the reinforcing elements are uniformly coated with matrix materials in exact proportions to obtain precisely the volume fraction required in the final composite. These precursor materials are microcomposites of the final structural material and require only the application of appropriate heat and pressure for consolidation into useful engineering forms. Phase I will demonstrate a novel microlayering approach that results in silicon carbide reinforced titanium aluminide alloy composites with significantly improved toughness. Thin gauge composite panels will be consolidated, and characterized and preliminary process/structure/property relationships will be developed to establish their potential for structural use in turbine engine hot-section components. Phase II will refine the process, introducing diffusion barriers and optimizing design of composite microstructure and consolidation protocols, and a prototype structural component will be demonstrated. These new MMC's will find near-term application as combustor liners in advanced turbines and, soon after, in rotor components. In aircraft turbines, weight savings of more than 50% offer dramatic improvements in fuel economy. In land turbines, increasing inlet temperatures only 100¿F can produce 5% efficiency improvements significantly lowering energy costs.