MateriAlZ Seminar: Naresh Thadhani
Friday, January 21, 2022, 11 a.m. MST
Naresh Thadhani
Professor and Chair, School of Materials Science & Engineering
Georgia Tech
"Probing Materials In Dynamic High-Pressure Environment Using X-ray Phase Contrast Imaging"
Zoom Link | Passcode: 699823
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ABSTRACT
Exploring materials in dynamic high-pressure environments is a research frontier that is attracting significant interest because of exciting materials science opportunities, combined with the immense challenges it poses with such studies. During dynamic high-pressure shock compression materials are exposed to states that allow studies in regimes not easily accessible by other methods. Under such conditions, materials undergo chemical changes creating new compounds through novel chemistries, physical changes forming metastable high-pressure phases, and mechanical changes through unique deformation and failure processes. Probing changes in materials in real-time and determining the effects of microstructure on underlining mechanisms is challenging due to the inability of conventional diagnostics to monitor dynamic events with nano- to micro-second time resolution and micro- to mesoscale spatial resolution. This presentation will review the use of X-Ray Phase Contrast Imaging (X-PCI) as an in-material diagnostic to determine the effects of process-inherent heterogeneities on the high-pressure shock-compression response of AM-fabricated high-solids (Silica particles) filled polymer composites. By tracking features across the observed shock front with ~154 ns time resolution and 2.45-micron spatial resolution of the X-PCI, we can determine the shock velocity versus particle velocity equation of state (EOS). The interior deformation fields in the samples are also quantified using digital image correlation (DIC) analyses performed on the X-PCI images providing an assessment of the average strain fields inside the polymer composite under shock-compression loading. The overall results demonstrate the utility and effectiveness of “in-material” X-PCI probing to determine the equation-of-state and interior strains associated with shock compression of heterogeneous materials.
BIO
Naresh Thadhani is Professor and Chair of the School of Materials Science and Engineering at Georgia Tech (GT). He joined the GT faculty in 1992, after six years working in the Center for Explosives Technology Research at New Mexico Tech and two years as a post-doc at CalTech. He received his B.E. from Malaviya National Institute of Technology in Jaipur, India, M.S. from South Dakota School of Mines, and Ph.D. from New Mexico Tech, all in Metallurgical Engineering. Dr. Thadhani’s research focuses on fundamental mechanisms of high-pressure, shock-induced physical, chemical, and mechanical changes and the deformation and fracture response of metals, ceramics, polymers, and composites, subjected to ballistic impact and high-strain-rate loading. He has advised 15 visiting scientists/post-docs; 33 Ph.D. and 19 M.S degree students; and mentored about 100 undergraduate researchers, with sponsored research funding exceeding ~$18M. He is a recipient of the 2018 TMS Leadership award, a Fellow of ASM International and American Physical Society, and the Academician of EuroMediterranean Academy of Arts & Sciences.