9408552 Clemens The purpose of this research is to investigate and optimize the strengthening mechanisms in epitaxial metal multilayers. A previous grant developed the capability for growing and structurally characterizing epitaxial (001) oriented FCC/BCC superlattices by sputter deposition. Hardnesses of these materials were investigated and enhancements nearly 300% found over the rule of mixtures. This remarkable phenomenon is the subject of this continued program. Using singly-oriented, epitaxial films, both the mismatch and relative thickness of layers are varied to deduce plastic flow mechanisms. Structural characterization involves high resolution cross-section transmission electron microscopy of as-deposited and deformed materials so that the atomic scale defects responsible for deformation can be identified. This information is incorporated into the modeling component of the program, which utilizes both continuum and atomistic approaches. %%% One result of this program will be metal films of unusually high hardness. These films could find applications in semiconductor, information storage, and coatings technologies. In addition, this program should develop fundamental understanding about plastic deformation in layered materials and ultra-thin films. ***
