Interdisciplinary Seminar in Nonlinear Science

Title: Control of binary alloy crystal growth patterns
Speaker: Wolfgang Losert
Speaker Info: University of Maryland
Brief Description:
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Alloys exhibit a large range of complex structures on a micrometer to mm scale, which influence important material properties such as strength or stiffness. Our approach to microstructure control is based on in situ dynamical selection of a pattern during crystallization. Using laser or UV light to locally perturb a transparent model alloy, we can alter the growth dynamics and guide the crystal toward new stable microstructures. For example, during directional solidification of a binary alloy, we can trigger a transition from a stable cellular microstructure to a stable dendritic microstructure. We also use perturbations to quantify, how stable a microstructure is. Theoretical calculations of response functions of the pattern and phase-field model simulations are key to interpreting our results. I will also show in-situ measurements of three-dimensional crystal growth patterns obtained with a two-photon confocal microscope.
Date: Friday, April 5, 2002
Time: 2:00PM
Where: Tech M416
Contact Person: Paul Umbanhowar
Contact email: umbanhowar@northwestern.edu
Contact Phone: 847 467-7291
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