Nanocomposites for High-Temperature Nozzles in Rocket Engines

"Materials used for the rocket-engine nozzles, hot-gas valves and turbopump blades, require high elevated-temperature tensile and creep strength, ductility, hardness, and fracture toughness as they operate at temperatures (¿¿ 2200K) well above the meltingpoints of state-of-the-art intermetallics and superalloys. Current techniques to manufacture W-Re-0.32HfC and W-Re-ThO2 alloys include sintering of elemental powders and arc and electron-beam melting of presintered tungsten-rhenium alloys. These methodsresult in exaggerated grain growth thereby severely impairing these alloys¿_ high-temperature properties. The objective of this Phase I effort is to select and manufacture nanocrystalline W-Re alloys with nanosize HfC,TiB2, and ThO2 dispersoids, whichwill exceed or meet the performance characteristics of the conventionally sintered alloys. These composite powders will be rapidly hot-consolidated to near-theoretical density at substantially lower processing parameters enabling considerable savings inmanufacturing and processing costs. The manufactured components are expected to be extremely ablation and erosion-resistant in various operating environments. Phase I will focus on research and development for optimization of the synthesis,consolidation, and characterization while Phase II will concentrate on optimization of process-structure-property-performance parameters and building and testing of the prototypes resulting in a stand