Investigation of thermal equilibrium defects in Fe-5.2 at.% Cr solid solution

The Mossbauer spectra of Fe-57 were measured for the thermal equilibrium bcc Fe0.948Cr0.052 solid solution being at temperature ranging from 300 to 1100 K. The obtained data were analysed in terms of concentration of unoccupied sites in the 14-site surroundings of an 57 Fe Mossbauer probe in the sample. It turned out that the analysis can be successfully performed when the temperature of the sample does not exceed 900 K, i.e. when probabilities of formation of "clear" (Schottky) vacancies as well as vacancies forming the separate interstitial-vacancy (Frenkel) pairs are negligibly low. At the same time the analysis showed that concentration of vacancies detected by the nuclear probe increases with temperature very rapidly-at the rate of about 10(-4) K-1. The result supports our earlier findings obtained for the quenched samples of the same alloy that the Mossbauer probe is sensitive to a possible thermal distortion of the crystalline lattice. (C) 2003 Elsevier B.V. All rights reserved.