The Role of Crystallographic Defects in Ceramic Superplasticity

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NON-TECHNICAL DESCRIPTION: This project studies how defects in materials (primarily misaligned atoms in a line or at a boundary) can be deliberately introduced to make ceramic materials ductile at high temperatures. Potential economic savings are possible for the ceramics industry in the U.S. for use in shape-forming complex oxide ceramic components at high temperatures while retaining excellent room temperature mechanical properties. This research helps train a diverse cohort of graduate and undergraduate students and provides the basis for a new graduate course on Grain Boundaries and Interfaces in Materials that will be introduced into the curriculum. TECHNICAL DETAILS: In addition to promoting possible commercial applications of superplastic forming by designing new superplastic ceramics, this research will contribute to understanding the fundamental deformation mechanisms operative in mullite and mullite composites at high temperatures. For the first time the dislocation structure and slip system will be determined for mullite, a material proposed for use in high temperature structural applications due to its excellent thermal stability, high thermal shock resistance, and low thermal conductivity. Students will be trained in the advanced techniques of high resolution atomic force microscopy (AFM) and focused ion beam (FIB) instrumentation to study relative grain boundary sliding and the role of interfacial defects.