Computational Design of Oxidation and Creep-Resistant Niobium Superalloys for High Temperature Turbine Applications

Rising natural gas prices, concerns about CO2 and NOx emissions, and a desire to efficiently utilize coal resources have increased interest in Integrated Gasification Combined Cycle (IGCC) and other advanced power plant technologies that promise to be environmentally friendly, to emit lower levels of pollutants, and to provide efficiencies that are significantly better than current technologies. In order to meet long-term IGCC power-plant goals (e.g. efficiency > 50%), gas turbine firing temperatures need to be higher than 1500C (2372F), which corresponds to turbine metal surface temperatures between 1100C and 1500C. This temperature range is beyond the limits of current nickel-based superalloys (which begin to melt at ~ 1250C), thus necessitating the need for a new class of superalloys that can operate at such temperatures while retaining sufficient strength, creep-resistance, fatigue-load-resistance, and other properties. Niobium ¿ which has a melting temperature of 2467C, is inherently ductile, and has a low density ¿ would be an attractive candidate for replacing nickel in turbines, provided that its limitations with respect to oxidation and creep-resistance can be solved. This project will design and develop oxidation- and creep-resistant niobium-based superalloys for high temperature turbine applications at 1300C and above. Commercial Applications and other Benefits as described by the awardee:The new niobium-based superalloys would enable the development of turbines for high-efficiency, zero-emission, coal-fired power plants. The technology also would be applicable to the development of advanced aerospace engines, providing performance increases and cost savings to the aerospace industry