Atomic scale analysis and phase separation understanding in a thermally aged Fe–20 at.%Cr alloy

Abstract Fe–Cr model alloys are of interest for understanding of phase separation in structural material for fusion or fission reactors. This motivated the quantitative study of the phase separation in a thermally aged (773 K) Fe–20 at.%Cr alloy using a Tomographic Atom Probe. It is shown that the chromium content in the α ′ phase evolves with ageing time synonymous of a non-classical nucleation mechanism. The overlap of the nucleation and coarsening regimes is observed. A non-steady coarsening regime occurs before 1067 h of ageing. The solubility limit at 773 K is found to be 14 at.%. A maximum concentration of (83 ± 1) at.% is observed for the Cr-concentration in α ′ precipitates.

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