Dr. Fadi Abdeljawad
Associate Professor
Department of Materials Science and Engineering
Lehigh University
Abstract
Nearly all structural and functional materials are polycrystalline systems; they are composed of differently oriented crystalline grains that are joined at internal interfaces, termed grain boundaries (GBs). It is well accepted that GBs play a critical role in controlling the observable properties of engineering materials. In this presentation, which is delivered in two parts, we present our recent work dealing with interfacial dynamics during processing treatments and under operating environments.
We first start by examining a GB-driven instability that has direct implications to additively manufactured lattice materials. We demonstrate using theoretical, computational, and experimental studies a morphological instability, in which a polycrystalline micro- or nano-rod breaks up at GBs into an array of isolated domains. We show that GBs play a destabilizing role in which the critical wavelength for the instability decreases with the increase in GB energy. Computational studies predict temporal evolution of interfacial profiles in quantitative agreement with experimental observations on microrods.
We then direct our attention to the role of GB chemistry in controlling coarsening processes in nanocrystalline (NC) alloys. Of particular interest is GB solute drag which occurs when alloying elements segregate to GBs hindering boundary motion. With the aid of a recently developed model, we show that GB solute drag exhibits a self-similar behavior, in which the maximum drag scales with the boundary heat of mixing. A new drag-velocity relation is proposed and used to explain recent experimental observations of sluggish grain growth in engineering alloys.
About Fadi Abdeljawad
Dr. Fadi Abdeljawad is an Associate Professor in the Department of Materials Science and Engineering at Lehigh University. Prior to joining Lehigh in 2023, he was an Assistant-then-Associate Professor (2018-2023) at Clemson University. From 2014-2018, Dr. Abdeljawad was a Staff Scientist in the Computational Materials and Data Science Department at Sandia National Laboratories. He obtained his M.A. (2010) and Ph.D. (2014) from Princeton University. He is a recipient of the Army Research Office Young Investigator Program (YIP) Award; TMS Early Career Faculty Fellow Award; and Ralph E. Powe ORAU DOE Award. Abdeljawad’s research, which is funded by DOD, DOE, NSF, and U.S. National Laboratories, is focused on microstructure formation and evolution, interface physics, and mechanics. His work has been featured in journals such as Physical Review Letters, Nano Letters, Applied Physics Letters, and Nanoscale.
