The Fall 2023 MatSE 590 for graduate students consists of an exciting and jam-packed schedule. MATSE 590 is a colloquium (1-3 credits) consist of a series of individual lectures by faculty, students, or outside speakers.
Graduate students will receive a weekly email with information via @psu.edu email. Graduate students are required to attend all 590 Seminars. If you have any questions, please email GradOffice@matse.psu.edu.
Program overview presented by Prof. John Mauro
CAPS (Counseling & Psychological Services)
September 14, 2023 - "Nanotwin Formation in Thin Metal Films"
Shefford P. Baker, Associate Professor of Materials Science and Engineering, Cornell University
Abstract
FCC metal films produced by atom-by-atom deposition methods can be formed with dense arrays of parallel coherent twin boundaries (CTB’s) having average spacings in the nanometer regime. These nanotwinned structures have been of great interest due to their expected exceptional properties. However experimental control of average CTB spacing has yet to be demonstrated and existing models provide conflicting predictions. We have simulated nanotwin formation during layer-by-layer growth as a function of deposition rate and temperature using a kinetic Monte Carlo (KMC) approach. To obtain good statistics, simulations must run from nucleation, growth, and island interaction to layer completion many times. To facilitate this, we developed a simplified code that, while inaccurate, nonetheless retains enough essential physics that we are able to describe in detail both how the CTB spacing should vary with rate and temperature and the failure of experiments to produce repeatable trends. As a bonus, we present a possible explanation for a phenomenon where one grain can be full of nanotwins while its nominally identical neighbor has none. Use of this simple KMC model provides a very different perspective on nanotwin formation than has been previously presented. A critique of the nanotwin literature and comments on the effective practice of science may be of particular interest to students.
Biographical Information
Shefford P. Baker is on the faculty in Materials Science and Engineering at Cornell University. His research focuses interactions among stresses, structure, and mechanical performance of materials, particularly those having critical length scales in the nanometer regime. His interests include relating processing to structure, defects, and stresses in thin films including texture and phase transformations; structure, composition, and deformation mechanisms in silicate glasses; defects and nanomechanical behavior in biogenic minerals and their synthetic analogs; nanocontact mechanics; and structure and deformation in advanced metals. Baker is a Fellow of the Materials Research Society and is a past President and Publications Committee Chair of that organization. He created a Master of Engineering Program in MSE at Cornell with a unique professional development component and has won several teaching awards at Cornell. He holds a PhD in Materials Science and Engineering from Stanford University, and was a staff scientist and the Max Planck Institute for Metals Research in Stuttgart before joining Cornell.
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