Self-organized alloy microstructures for extreme environments

with Paul Bellon
Donald W. Hamer Professor, Materials Science and Engineering at Illinois
Dec 2, 2022, 10:10 AM

Materials are commonly subjected to external forcing, for instance plastic deformation during fabrication and shaping, and irradiation during service life in nuclear reactors. While such nonequilibrium forcing can introduce detrimental evolution of material properties, it also creates opportunities for the dynamical stabilization of novel microstructures via self-organization. In particular, ion irradiation and plastic deformation can result in the stabilization of intragranular and grain boundary nanoprecipitates with finite steady-state size. These nanoprecipitates can impart radiation resistance by providing a large and stable density of interfacial sites for point defect elimination, while at the same time improving mechanical properties. Atomistic simulations and phase field modeling of these non-equilibrium metallic alloys are employed to map out the domains of stability of various steady states. Self-organization is found to result from the competition between antagonistic dynamical processes, and in simple cases, self-organization is rationalized as driven by effective free energies and effective interface energies. Simulations and modeling results are compared with experiments on model Cu-based and Al-based alloys. It is shown that self-organization, and self-adaptation, can lead to significant improvements for microstructural stability in extreme environments.

Pascal Bellon is the Donald W. Hamer Professor in the Department of Materials Science and Engineering at Illinois. In 1996, after working as a research scientist at CEA-Saclay, France, he joined the Department of Materials Science and Engineering at the University of Illinois at Urbana-Champaign as a tenure-track Assistant Professor, and was then promoted to Associate Professor in 2002 and Full Professor in 2009. He received an NSF CAREER award in 1998. He was named a Racheff faculty scholar in 2012 and he was inducted as the Donald W. Hamer Professor at Illinois in 2016. Dr. Bellon served as interim Department Head in Materials Science and Engineering at Illinois in 2019. His research focuses on materials driven into non-equilibrium states by external forcing such as irradiation by energetic particles and plastic deformation, and how nanoscale self-organization can improve their performance in service via self-adaptation. The research combines experiments, including nanoscale characterization by transmission electron microscopy and atom probe tomography, atomistic simulations and continuum modeling.