Point defect concentrations and hardening in binary B2 intermetallics

Point defect hardening in binary B2 intermetallic compounds with the anti-structure defect structure (FeCo and AuZn) and the triple defect structure (NiAl, FeAl, and CoAl) was investigated. Thermodynamic modeling combined with experimental measurements of lattice parameters and bulk densities were used to establish point defect concentrations as Functions of composition and temperature. Microhardness measurements were made on samples of varying compositions and quenching temperatures. Solution hardening rates of vacancies were found to be significantly larger than those of anti-site defects. II was possible to relate the hardening rates of anti-site defects to the magnitude of the lattice dilation. This suggests that the elastic size effect was the primary hardening mechanism. No such correlation was found for vacancies. (C) 1997 Acta Metallurgica Inc.