Special Seminar: Promoting beneficial complexion transitions—Using defects to make better materials

Timothy Rupert, Associate Professor, Materials Science & Engineering, University of California - Irvine

Monday, January 14, 2019, 3:30–4:30pm

Rm. 100 (Spanos Auditorium), Cummings Hall

Doped interfaces can have intriguing structures and, in some cases, thermodynamically-stable interfacial states can form. In this talk, we explore the usage of such “complexions” in nanostructured metal alloys, with a focus on how these features can be used to solve long-standing challenges concerning limited ductility and thermal stability. Atomistic simulations are used to identify the effects of chemistry, temperature, and boundary character on grain boundary structural transitions, as well as understand how these features impact plasticity and fracture. Experimental validation is provided by high resolution transmission electron microscopy on specially-designed thin film samples that systematically explore these variables, as well as nanocrystalline alloys produced through powder metallurgy. Micron-scale experiments are then used to quantify the effect of doping on mechanical behavior, showing that strength, strain-to-failure, and failure mode can be controlled with the addition of segregating dopants. Finally, we extend the concept of complexions to line defects, showing that dislocations can also sustain a number of interesting nanoscale phases. As a whole, this work lays the foundation for the engineering of defect structure to design better materials.

About the Speaker

Professor Tim Rupert is an Associate Professor of Materials Science and Engineering at the University of California, Irvine, with a joint appointment in Mechanical and Aerospace Engineering. He received a BS/MS in mechanical engineering from Johns Hopkins University in 2007 and a PhD in materials science and engineering from MIT in 2011. Professor Rupert’s research focuses on uncovering new structure-property relationships in nanomaterials for structural and energy applications, as well as increasing the reliability and lifetime of these materials. To achieve their research goals, his lab uses a combination of computational and experimental techniques. In recent years, Prof. Rupert has received an NSF CAREER Award, a DOE Early Career Research Program Award, an ARO Young Investigator Program Award, a Hellman Fellowship, and the ASM International Bradley Stoughton Award for Young Teachers.  He serves on the editorial boards of Materials Science and Engineering A, Metallurgical and Materials Transactions A, and Scientific Reports.

For more information, contact Holly Buker at +1 (603) 646-3546 or holly.a.buker@dartmouth.edu.