Solid-Phase Reactions in Mechanically Activated Nanocrystalline Fe–Cr Alloys upon Thermal Treatment

X-ray diffraction and Mössbauer spectroscopy are used to study solid-phase reactions that occur in Fe–Cr nanocrystalline alloys during heat treatment. Upon the isochronous annealing of mechanically alloyed Fe–Cr powders, the nanostructural state is retained for all samples up to a temperature of 700°C. Fe(80)Cr(20) alloy tends to separate throughout the range of annealing temperatures. The annealing of all samples in the temperature range of 400–500°C results in separation into iron-enriched and chromium-enriched regions. A change in the trend toward short range ordering is observed in the samples of Fe(70)Cr(30) and Fe(60)Cr(40) at annealing temperatures above 500°C. Annealing samples of Fe(52)Cr(48) at temperatures above 600°C results in the formation of the σ-phase.