Bulk density and dilatometer measurements were carried out on stoichiometric material in order to determine the thermal vacancy concentrations as a function of time and temperature. For temperatures of 600C and below, the specimen bulk density or length were found to depend upon the heat treatment history, and were not unique functions of the temperature. This path-dependence suggested a lack of active sources and sinks for thermal vacancies at temperatures below about 600C.

On the Path Dependence of the Thermal Vacancy Concentration in Stoichiometric FeAl. J.H.Schneibel, P.R.Munroe: Intermetallics, 2004, 12[1], 111-5