MSE Colloquium: Joshua Kacher, Understanding degradation and failure mechanisms by multiscale and in situ electron microscopy

Joshua Kacher

Abstract

Mechanical deformation and failure processes such as fatigue crack formation and ductile fracture are inherently multiscale processes, ranging from nanoscale crack nucleation mechanisms to collective dislocation interactions ranging across hundreds of microns. Understanding these processes requires multiscale characterization approaches that reflect the nature of the processes. Advances in electron detector technology, including the advent of direct-electron detectors, and increases in computational processing capacity have transformed electron microscopy-based characterization into a big-data analytics tool capable of multimodal image acquisition and high-resolution property mapping. This includes the ability map out the three-dimensional elastic strain tensor, crystal rotations, and dislocation density at length scales ranging from nanometers to hundreds of microns. BREAK In this talk, I will discuss the work my group is doing in applying advanced multiscale and in situ electron-microscopy based characterization techniques to understand mechanical deformation and corrosion mechanisms. I will focus my results on two materials applications: understanding the influence of second phase particles in ductile failure of Al alloys and determining the role of microstructure on the local corrosion sensitivity of Al alloys.
 

Bio

Josh Kacher joined the School of Materials Science and Engineering at Georgia Institute of Technology in 2015. Prior to joining the faculty at Georgia Tech, he was a post-doctoral research scholar at the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory and completed his Ph.D. at the University of Illinois at Urbana Champaign under the advisement of Ian Robertson. He is the recipient of a 2015 DOE Early Career Research Award, a 2017 ONR Young Investigator Award, and a 2021 NSF CAREER award. His primary research interests are in relating the performance of materials in extreme environments to their microstructure and processing history. This includes understanding how environmental factors such as elevated temperature or corrosive elements affect the mechanical properties and failure modes of materials. These phenomena are investigated primarily using novel in situ and multiscale transmission and scanning electron microscopy techniques.
 

 kacherlab.gatech.edu

This presentation will be in-person. If you are unable to attend, you can attend virtually using this Zoom link.

Zoom link

Password: 126701