b'Combinatorial and HighDemonstrated proof-of-principle blazes trail for computational materials Throughput Materialsengineering tools to help nuclear structural materials discovery and to reduce time and cost for irradiations in the Advanced Test Reactor.Synthesis to Advance Nuclear Materials Discovery R esearchers developed and demonstrated combinatorial workflows for structural materials discovery and neutron irradiation testing of structural materials. Using modern computational materials engineering tools to explore the complex composition space provided by the class of alloys known as multi-principal element alloys. Multiple compositions were selected for rapid fabrication in a fast-to-fail approach. This approach avoided the historical and time intensive iterative approach and allowed for rapid down selection of candidate PROJECT NUMBER:materials. Samples were also fabricated by both spark plasma sintering and arc 20A44-046 melting to provide further comparison of rapid fabrication techniques. Baseline characterization of the candidate materials selected and fabricated confirmed TOTAL APPROVED AMOUNT:modeling predictions, thus validating the use of the modeling tools for alloy design $1,486,000 over 3 years and initial selection. The presence of deleterious brittle phases, extremely high PRINCIPAL INVESTIGATOR:hardness, and poor ductility were found in some of the initially selected alloys. Jason Schulthess The modeling tools were then used to modify the compositions to obtain a softer major phase with a dispersed hard phase to enhance mechanical properties while CO-INVESTIGATORS: maintaining the potential for high temperature creep resistance. Evander Evans Chambers, INLThomas Maddock, INL A standard capsule for structural materials irradiation in the Advanced Test Reactor Frank Liou, Missouri University of(ATR) was developed and demonstrated by irradiating 240 specimens from 16 Science and Technology material compositions selected during the initial material discovery phase. While Joseph Newkirk, Missouristructural materials testing has previously occurred in ATR, the capsule design University of Science and Technology and fabrication process usually takes years to complete. To decrease the cost and time associated with future materials testing in ATR, the standard capsule was COLLABORATORS: designed to hold multiple specimen geometries and allow use in virtually any ATR CalNano, Inc. irradiation position. The standard capsule features locking endcaps that connect Central Valley Machine and lock together to form the capsule stack, eliminating the need for a basket and maximizing the quantity of specimens that are contained in the capsule. A thermal model was developed that requires only minimal changes to update the material properties and heating rates for new experiments. A key outcome is two additional irradiation experiments that are using the standard capsule design.20'