MSE Colloquium - Prof. Jeffery Rickman
Date: February 10, 2012 from 2:00 pm to 3:00 pm EST
Location: Room 214 S. W. Mudd
Contact: For further information regarding this event, please contact Wesley Hattan by sending email to wjh2121@columbia.edu or by calling 2128547860.
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Jeffrey M. Rickman
Dept. of Materials Science and Engineering and Dept. of Physics, Lehigh University

"The Role of Obstacles in Diffusive Transport and Defect Mobility

The presence of obstacles, such as oversized solute and precipitates, can hinder the motion of extended defects and the diffusion of matter in solids, thereby altering mechanical and transport properties. In this talk we employ computer simulation, analytical methods and experiment to investigate two illustrative examples, namely the hindrance of dislocation loop motion and the blocking of grain-boundary diffusion in ceramic oxides by dopants. In the first example we describe the effects of defects on dislocation mobility via level-set dislocation dynamics simulation and numerical coarse graining, and in the second example we examine the impact of isovalent dopants on diffusion and diffusional creep in alumina via simulation and experiment.  In both cases computer simulations provide useful insights into the underlying mechanisms governing defect motion and transport.