PROPERTIES OF ORDERED INTERMETALLIC ALLOYS - 1ST-PRINCIPLES AND APPROXIMATE METHODS

Intermetallic alloys which can be made ductile at low temperatures and strong at high temperatures are of great value as materials for curre nt and future high technology applications. Computational physics is a useful tool for locating candidate materials. The current generation of first-principles techniques can be used to study ordered phases of candidate materials. The results of these calculations may be used to construct highly accurate model potentials which can then be used to s tudy systems containing thousands of atoms, including impurities, void s, defects and cracks. First-principles calculations are used to compu te the elastic constants of a wide range of monatomic metals and order ed binary intermetallic alloys. The results are usually within 10% of the experimentally determined values. We also examine some of the high melting temperature A15 compounds. Total energy calculations for a si mplified model of an antiphase boundary are presented. These results c an be used to calibrate model potentials for use in studying the energ y of isolated defects. Finally, we study the possibility of using the Harris functional to speed total energy calculations.