Microstructure and Kinetics of the Ordering Transformation in Iron–Cobalt Alloys,FeCo,FeCo–0.4%Cr,FeCo–2.5%V

Abstract

Ordering in FeCo, FeCo–0.4Cr, and FeCo–2.5V is studied using X-ray diffraction, saturation magnetization, and optical and electron microscopy. The kinetics of the disorder to order transformation on isothermal heat-treatment of quenched alloys are determined over the temperature range 250–600°C. Between 500 and 600°C alloys order by a homogeneous process followed by coalescence of antiphase domains. Below ∼430°C FeCo and FeCo–0.4Cr order by nucleation and growth of ordered regions at grain boundaries, this mechanism does not occur in FeCo–2.5V. The grain-boundary ordered regions exhibit a faceted morphology.