b'Nanostructured Composite Alloys for Extreme EnvironmentsPrincipal Investigator: Osman AnderogluTeam Members/ Collaborators: N. Mara, M. Radhakrishnan, M. Knezevic, J. Gigax, and N. Lienvironments such as fast reactor clad-ding applications. Nanolayered (20-600 nm individual layer thickness) Cu/Nb and Zr/Nb composites were produced using innovative accumulative roll bonding (ARB) technique. Mechanical property and thermal stability studies were performed up to 600C followed by microstructural characterization. The selected alloys were irradiated up to 200 dpa using 5 MeV self-ions at 400-600C. High dose irradiations were performed for the first time on these Figure 1. A photograph of theO alloys as part of the project. Remarkable ne of the aims of the Fuel as-rolled h = 200nm ARB Cu/ Cycle R&D (FCRD) program isstability under irradiation was shown. Nb. A ruler measured in inches isto develop cladding materialsFindings show an innovative approach included for scale for production of advanced alloys for for very high burn up. This can be accomplished with materials that candemanding applications. The study on withstand very high irradiation doses.model bilayers indicates possibility of Conventional ferritic/martensiticproducing cladding materials both for steels are one of the candidate alloyssafer operation of current operating show significant embrittlement at lowreactors as well as new alloys for other temperatures (400C) and swellingdemanding environments of future For the first time,at medium temperatures (~450C)advanced reactors.accumulative rolldepending on the dose. A non-conven- Accomplishments:bonding processed bulktional promising alternative is nanolay- ARB processing of Cu/Nb and Zr/nanolayered compositesered composite alloys. Thanks to a veryNb nanocomposites down to 20nm showed remarkablehigh density of stable interfaces whichindividual layer thickness including void swelling resistanceprovides recombination sites for irradia- cross-rolling to change the interface at very high irradiationtion induced point defects these alloysstructure at the same layer thickness doses (200-450 dpa,show remarkable radiation resistance.was accomplished (N. Mara, J. Cheng, 400-600C). Furthermore, they can be designed forU of Minnesota; Danial Savage, Marko envisioned medium (coolant, tempera- Knezevic, U of New Hamshire) while ture, etc.) so that they can perform ina new ARB processing capability was the extreme environments. also established at UNM (O. Anderoglu, Project Description: M. Radhakrishnan). After processing, The objective of this proposal is tomicrostructure characterization develop extreme performance bulkincluding scanning electron micros-nanocomposite alloys that can withstandcopy , detailed texture analysis using very high irradiation doses at elevatedneutron diffraction and transmission temperatures for demanding nuclearelectron microscopy (TEM) were 112 2021|AFC ACCOMPLISHMENTS'