Point defects in B2-type intermetallic compounds

Recent development in investigations of point defect structure in B2-type intermetallics is surveyed, mainly focusing on those by authors’ group. Systematic X-ray and neutron diffraction experiments showed that B2 alloys exhibit hybrid defect behavior, i.e. four kinds of defects (antisite defects and vacancies) generally coexist in this type of materials. Careful density measurements strongly suggest that constitutional vacancies do not exist even in NiAl. A thermodynamic model based on the Bragg–Williams method reproduces well the observed trends in B2 NiAl and FeAl alloys.