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Events for November 05, 2019
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Mork Family Department of Chemical Engineering and Materials Science Seminar - Distinguished Lecture Series
Tue, Nov 05, 2019 @ 04:00 PM - 05:20 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Speaker: Professor Jason R. Trelewicz, Department of Materials Science and Chemical Engineering. Stony Brook University
Talk Title: Controlling the Stability and Radiation Tolerance of Nanocrystalline Alloys
Abstract: Stable nanocrystalline phases leveraging grain boundary segregation are being realized in a myriad of alloy systems and driving advances in the design of bulk nanocrystalline materials. However, augmenting the chemical state of the grain boundaries for stabilization purposes can also have marked impacts on their structure and in turn, the performance of the material in extreme environments. In this presentation, we explore nanoscale grain boundary engineering approaches for the design of tungsten as a plasma facing material for fusion reactors. Dopant species and concentrations are first identified through lattice Monte Carlo modeling and used to guide powder metallurgy synthesis of ternary nanocrystalline tungsten alloys. Through synchrotron x-ray diffraction and small angle x-ray scattering experiments, we select optimized alloy chemistries containing nanoscale compositional heterogeneities for enhanced stability and sinterability. In light of these results, we then probe the effect of grain boundary doping on the coupling between microstructural evolution and irradiation damage state using in situ heavy ion irradiation experiments. Defect evolution is mapped up to 20 dpa and bridged to high-dose stability using ex situ experiments up to 400 dpa. The addition of grain boundary dopants is shown to stabilize the nano-alloy against irradiation induced grain growth, which is correlated to evolving defect state out to the maximum dose of 400 dpa. Mechanistic insights on the role of grain boundaries in damage accumulation are gained using molecular dynamics displacement cascade simulations, demonstrating that the grain boundary character and damage proximity govern the balance between defect formation, migration, and recombination.
Host: Dr. Hodge
Location: John Stauffer Science Lecture Hall (SLH) - 102
Audiences: Everyone Is Invited
Contact: Karen Woo/Mork Family
