POINT-DEFECT CONCENTRATIONS AND HARDENING IN BINARY B2 INTERMETALLICS

Point defect hardening in binary B2 intermetallic compounds with the a nti-structure defect structure (FeCo and AuZn) and the triple defect s tructure (NiAl, FeAl, and CoAl) was investigated. Thermodynamic modeli ng combined with experimental measurements of lattice parameters and b ulk densities were used to establish point defect concentrations as Fu nctions of composition and temperature. Microhardness measurements wer e made on samples of varying compositions and quenching temperatures. Solution hardening rates of vacancies were found to be significantly l arger than those of anti-site defects. II was possible to relate the h ardening rates of anti-site defects to the magnitude of the lattice di lation. This suggests that the elastic size effect was the primary har dening mechanism. No such correlation was found for vacancies. (C) 199 7 Acta Metallurgica Inc.