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ChBE Seminar Series: In-situ TEM Studies of High Entropy Nanomaterials Speaker: Reza Shahbazian-Yassar, professor of mechanical and materials engineering, University of Illinois at Chicago Abstract:
High entropy materials are emerging materials with significant increase in their configurational entropy making them very stable in extreme service conditions. Despite such tremendous potential, it is not clear how these materials behave under reactive gaseous or liquid environment and/or at elevated temperatures. This presentation will summarize the recent efforts of this PI and the team of his collaborators on nanoscale dynamic imaging of high entropy nanoparticles under high temperatures, oxidative, and reductive gases. Initially, we studied the behavior of Fe0.28Co0.21Ni0.20Cu0.08Pt0.23HEA nanoparticles (NPs) in air environment by in situ gas-cell TEM. We found that the oxidation of HEA NPs is governed by Kirkendall effects where the oxidation rate is significantly lower than monometallic or binary alloys. In another in-situ gas-cell TEM study, we investigated the behavior of high entropy alloy nanoparticles under hydrogen (H2) environment. It was noticed that the reduction reaction front was at the external surface of the oxide layer that was present on the surface of high entropy nanoparticles. During reduction, the oxide layer enlarged and transitioned into porous structures. Revealing the oxidative and reductive behavior of HEA NPs facilitates the development of advanced multicomponent alloys for applications targeting structural alloys, high temperature materials, corrosion-resistive materials, hydrogen embrittlement protection, and catalytic oxidation or hydrogenation. These studies are utmost importance for the promising applications of high entropy materials in catalysis, electronics, structural mechanics, and energy storage. Biography:
Dr. Reza Shahbazian-Yassar is a professor in the Department of Mechanical and Materials Engineering at the University of Illinois, Chicago. He received his PhD in Materials Science from Washington State University in Pullman, WA, and then started his career at Michigan Technological University in 2007 as an assistant professor. Later, he was promoted to Henes Chair Professor of Nanotechnology. Shahbazian-Yassar has published more than 240 papers in journals such as Science, Nature Nanotechnology, Nature Energy, Nature Communications, PNAS, and many more. He served as the President for Midwest Microscopy Society, is a member of Steering Committee for ASME NanoEngineering for Energy Committee, and the former chair of the Advanced Characterization, Testing, and Simulation (ACTS) Committee at The Materials Society (TMS). He is also on Editorial Board for Metallurgical and Materials Transactions A (MMTA). This Event is For: Campus
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