A novel approach for increasing radiation resistance of multicomponent alloys using synergistic solutes

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NON-TECHNICAL SUMMARYMaterials employed in current nuclear reactors suffer from detrimental evolutions triggered by their continuous exposure to irradiation by energetic particles, resulting in limited service life. The research explores a novel approach to dramatically suppress the kinetics of some of these evolutions through minor addition of alloying elements. Since it is now known that addition of one solute can only imperfectly meet the many functions required for that goal, here a combination of synergistic elements is pursued. Atomistic simulations and modeling are used to identify the most effective combination of such alloying elements, and nanoscale experiments are designed to test and validate the proposed approach on model metallic alloys, including Cu-based alloys. This research impacts broadly the development of alloy design strategies for new materials that are critical to advanced energy technologies. The program supports the development of workforce in the Science, Technology, Engineering and Math fields by supporting two graduate students and several undergraduate students. The research is integrated with undergraduate education by developing modeling modules and by implementing active learning techniques in the courses taught by the PIs.TECHNICAL SUMMARYThis fundamental research investigates the use of solute additions for trapping point defects toward the design of radiation resistant alloys. The motivation stems from the recognition that the sustained fluxes of point defects to sinks such as grain boundaries and dislocations is the main factor contributing to the long-term degradation of materials during irradiation. In alloys, moreover, defect fluxes often couple to chemical fluxes, resulting in irradiation-induced segregation or even precipitation at sinks. An attractive solution is to increase point-defect recombination by adding point defect-trapping solutes. The challenge is to identify the best solutes that can trap point defect efficiently, without being progressively removed from the matrix by solute drag due to defect fluxes. The proposed research introduces the novel idea of using synergistic solutes to meet these multiple requirements, employing first principles calculations to determine solute-point defect interactions and self-consistent mean-field theory to calculate defect and solute transport coefficients. The experimental program aims at measuring directly the effect of solute on the overall vacancy diffusion and on solute drag. This is achieved by measuring the broadening and the drift of thin marker layers placed at strategic positions in a Cu thin film using atom probe tomography. The proposed experimental program is complemented by kinetic Monte Carlo simulations. The broader impact of the research includes the development of alloy design strategies for new materials that are critical to advanced energy technologies. The project will also establish an international collaboration with Dr. T. Schuler, from CEA, France, on the modeling of point defects and solute coupled transport. In addition, research and teaching will be integrated by developing computational modules for undergraduate courses and by mentoring undergraduate students through research experiences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.