UNUSUALLY HIGH VACANCY CONCENTRATIONS IN NI3SB

The structure of the intermetallic alloy Ni3Sb (the high-temperature p hase) has been studied by means of neutron diffraction. Alloys with Ni contents between 71 and 75 at.% were examined at temperatures ranging from 600 to 1000 degrees C. The results confirm DO3 structure as well as the existence of vacancy concentrations of up to 20% of the Ni sit es. The high number of vacancies certainly plays a crucial role in sta bilizing the DO3 phase; it is also held responsible for the extraordin arily high Ni diffusivity values found in tracer diffusion studies.