Natural mechanism of the broadened Snoek relaxation profile in ternary body-centered-cubic alloys

Abstract

The natural mechanism of the broadened Snoek relaxation peak in the ternary bcc alloy system has been investigated by an embedded-cell model of statistical mechanical treatment. In this method, interstitial sites of different geometries (octahedral, tetrahedral, etc.) in bcc crystals are considered and further distinguished by element species and atomic arrangements within their first shell of the neighbors. Following these preconditions, the interstitial site occupancies, the spatial configurations, and the transition probabilities of the interstitial atoms are concretely calculated for the ternary bcc alloy system, and all possible elementary relaxation processes contributing to the broadened Snoek peak are physically described with the determined activation energy and peak temperature for each elementary process. Using this approach for Snoek peak deconvolution, the broadened Snoek peak of the ternary bcc alloy can be resolved into several elementary Debye peaks, which correspond to the concrete relaxation mechanism. In the present study, this method is successfully applied to analyze the natural mechanism of experimentally observed Snoek relaxation in Nb-Ti-O systems.