Department Seminar with Sai Mu: Exploring Electron Scattering and Lattice Vibrations in Disordered Concentrated Solid Solution and High Entropy Alloys

Date/Time
Date(s) - 21 Oct 2019
3:10 PM - 4:00 PM

Location
1213 Hoover Hall

Speaker: Sai Mu, Postdoctoral Research Associate at the University of California at Santa Barbara

Title: Exploring Electron Scattering and Lattice Vibrations in Disordered Concentrated Solid Solution and High Entropy Alloys

Abstract: Today, disordered alloys are commercially ubiquitous and underpin virtually all advanced technologies – energy, transportation, construction, communication, medicine. Most importantly, recently discovered maximally disordered alloys – High Entropy Alloys (HEAs), and their cousins general multicomponent concentrated solid solution alloys (CSAs) – exhibit exceptional physical properties, resulting in the emergence of a new paradigm. Understanding how chemical complexity influences the underlying electronic and vibrational properties of such complicated alloys is the subject of this talk. I will discuss two topics regarding HEAs and CSAs. In the first work, using ab-initio electronic structure methods for describing the effects of disorder on the underlying electron glue responsible for cohesion, and electrical resistivity as an arbiter, the electron scattering mechanisms of maximally disordered alloys are delineated and the dominant one is identified1,2,3. In another work, we explore the pure effect of force constant disorder on lattice vibrations and phonon scattering in CSAs4. We reveal that the large, and heretofore unrecognized, impact of local chemical environments on the distribution of the species-pair-resolved force constant can dominate the phonon scattering. The physics revealed here has broad implications and paves the way on the alloy design towards targeted properties – such as energy dissipation, phase stability, mechanical property – based on the exploitation of extreme compositional complexity.

Bio: Sai Mu is a postdoctoral research associate in the field of condensed matter theory and materials science at the University of California at Santa Barbara. Mu received the Ph. D in physics from the University of Nebraska-Lincoln in 2014 and the B. S. in physics from Beihang University in 2008. 

Seminar Host: Duane Johnson

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