9510259 Daw This work investigates the fine structure of dislocations in the FeAl and NiAl pseudobinary systems. Specifically, it studies the details of dislocations and dislocation reactions in these compounds, using both atomistic (embedded- atom and tight-binding/density-matrix methods) and anisotropic continuum calculations. The investigator will explore four key features: (1) the core structure and mobility of a<111> dislocations; (2) the source of the yield strength anomaly; (3) the mechanism of the slip transition; and (4) deformation mechanisms above the slip transition. He is closely coordinating this theoretical work with the experimental efforts of Prof. Mike Mills of The Ohio State University. Such work will help to determine strategies for obtaining improved low-temperature ductility and high- temperature strength in these compounds. %%% This project theoretically investigates the properties of a class of intermetallic compounds, namely, iron-aluminum and nickel-aluminum. These materials are of considerable technological interest due to their attractive high- temperature properties and excellent oxidation and corrosion resistance (that is, they keep from rusting or breaking down). Applications include aerospace turbines, semiconductor coatings, and automotive components. In particular, the investigator will look at linear defects in these materials called dislocations that are responsible for many of the properties of interest. Once scientists better understand the dislocations, then they can develop better strategies in obtaining improved properties. The investigator is closely coordinating this theoretical work with the experimental efforts of Prof. Mike Mills of The Ohio State University. ***
