This award from the U.S.-Argentina Cooperative Science Program supports research in materials science to be conducted by Dr. Diana Farkas of Virginia Polytechnic Institute in collaboration with Dr. E.J. Savino and Dr. R. Pasianot of the National Atomic Energy Commission (CNEA) of Argentina. The goal of the project is to carry out computer simulation of defect structure in intermetallic alloys. The project continues an active collaboration in the area of theoretical models for radiation - enhanced diffusion. The project focuses on the development of empirical potentials of many body type suitable for computer simulation of extended defects in ordered alloys. These interatomic potentials will be applied to the simulation of point defects in pure metals and alloys and extended defects (grain boundaries and dislocations) in pure metals and in alloys and the interaction of these two types of defects. ***//