Systems-Based Design of Ferritic-Martensitic Superalloys for Generation IV Nuclear Reactors

78198S Future nuclear reactors (Generation IV) will operate at higher temperatures to allow for increased economic and energy efficiency, as well as to support thermochemical hydrogen production. Ferritic-martensitic alloys are attractive materials for this application, due to their resistance to void swelling under irradiation. However, currently available alloys do not have the necessary combination of creep resistance and corrosion resistance above 650¿C. Therefore, advanced alloys must be developed and qualified to operate at temperatures of 650 - 750¿C, while in contact with liquid metal coolants and exposed to high radiation levels. This project will develop a systems-based, computational approach that utilizes available thermodynamic and kinetic multi-component databases to design 9 ¿ 12% Cr steels capable of performing in this harsh operating environment. In Phase I, promising creep-resistant alloy systems will be identified by surveying the creep strengthening efficiency of potential precipitate phases, including novel coherent phases. For selected alloy concepts, relevant process-structure and structure-property models will be utilized for computational alloy design. Then, prototype alloys will be prepared to evaluate microstructural stability. High temperature tensile testing and short-time creep rupture tests will be conducted in preparation for creep studies in Phase II. Commercial Applications and Other Benefits as described by the awardee: The proposed ferritic superalloy would allow Generation IV nuclear reactors to operate at higher temperatures, allowing these reactors to produce hydrogen for fuel-cell powered transportation. The same alloys also could allow commercial natural gas and coal fired power plants to operate at higher temperatures, thereby improving the energy and economic efficiency of electricity generation.