Kinetics of α’-phase nucleation during thermal aging of Fe–22% Cr alloy

Abstract

The initial stage of phase separation of binary Fe–22 at % Cr alloy during thermal aging at 500°C is studied at the atomic-scale level by atom probe tomography. Upon the behavior analysis of pair-correlation function of chromium atoms, long-range correlations typical of spinodal decomposition are observed at short aging times, which disappear 25 h after aging. The analysis of 3D atomic maps shows that Cr-rich regions form at the initial steps of decomposition, where the chromium concentration increases with an increase in the aging time. At the aging time of ~100 h, the chromium concentration in the center of these regions reaches 80 at %, which corresponds to the α' phase.