Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:
Diffusionless transformations are those in crystalline solids in which atoms move cooperatively and virtually instantaneously, and in doing so, alter the volume and shape of the crystal, and thereby the crystal structure. The martensitic transformation, perhaps the most recognized of diffusionless transformations, gives rise to two classes of material response: a shape memory effect, which is stimulated by changes in temperature, and superelasticity, in which the solid reversibly transforms between crystal structures via strain. The volume change that accompanies the martensitic transformation also gives rise to strain mismatch between grains, which in brittle solids produces cracks that lead to failure. To avoid brittle failure in such systems, microstructural design plays a critical role. In this work we chose ceria-stabilized zirconia to explore microstructural strategies to circumvent brittle failure during such transformations, and have exposed these materials to mechanical compression and thermal treatments. Both shape memory and superelasticity could be examined through manipulation of the ceria content. Rather than relying solely on X-ray diffraction to track the degree of transformation, Raman spectroscopy was used to supplement XRD studies with differing length scales of analysis. It is anticipated that by coupling our understanding of martensitic transformations with zirconia-based microstructural design, opportunities for high-temperature actuation and energy damping are possible.

More about the Speaker:

Katherine T. Faber is the Simon Ramo Professor of Materials Science at Caltech. She earned her PhD in materials science and engineering from the University of California, Berkeley. Prior to joining Caltech, she held appointments at the Ohio State University and Northwestern University. Professor Faber is a fellow of the American Academy of Arts and Sciences, a Distinguished Life Member of the American Ceramic Society, and a fellow of ASM International. Among her awards are the Society of Women Engineers Distinguished Educator Award, the John Jeppson Award and the W. David Kingery Award, both of the American Ceramic Society, and the Edward DeMille Campbell Memorial Lecture of ASM International. She served as president of the American Ceramic Society in 2006–07. While at Northwestern University, she co-founded and co-directed the Northwestern University/Art Institute of Chicago Center for Scientific Studies in the Arts, where advanced materials characterization and analytical techniques are used in support of conservation science. Her research interests include the fracture and toughening of brittle materials, ceramics for energy-related applications, including thermal and environmental barrier coatings for power generation, porous solids for filtration and flow, and cultural heritage science.