HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY STUDIES OF DISLOCATION CORES IN METALS AND INTERMETALLIC COMPOUNDS

Considerations for the observation and analysis of dislocation cores in metals and intermetallics using high-resolution transmission electron microscopy are discussed. Specific examples treated are Lomer and 60 degrees dislocations in aluminum and a[011] edge dislocations in NiAl. The effect of thin-foil geometries on the structure and images of these dislocation cores is modeled using the Embedded Atom Method and image simulations. Some generalizations based on these calculations are discussed. Comparison of observed and simulated images enables determination of the spreading of the edge component of the cores, both in and out of the glide plane, which can have significant implications for the modeling of macroscopic behavior.