Tungsten Fiber Reinforced Oxidation Resistant Columbium Alloys

High-strength, oxidation-resistant composites were developed for use in turbine engines at 2000F. A composite system with columbium alloy matrices and tungsten filaments was selected and evaluated for oxidation resistance and mechanical properties. These composites were intended for use in the coated condition with the oxidation-resistant matrix providing fail-safe protection. The coated composite with 27 volume percent reinforcement had excellent stress-rupture strength (100-hour rupture strength of 25 ksi at 2200F), elevated-temperature strength (33 ksi at 2600F), and isothermal-oxidation life (>1100 hours at 2000F). However, both the fail-safe life(e.g., 50 one-hour cycles at 2000F) varied with the composition of the matrix. With continued work, it should be possible to tailor the properties of this composite system so that desired properties can be optimized for specific high-temperature applications. (Author)