A study of the effect of ageing temperature on phase separation in Fe45%Cr alloys

Atom probe and position-sensitive atom probe microanalyses have been performed to examine the microstructures resulting from spinodal decomposition in a series of FeCr alloys thermally aged at 400°C. A comparison with microstructures from Fe45%Cr alloys aged at 500°C showed that the activation energy for diffusion was approximately 2.3 eV. The increase in the scale and composition of the αα′ domains was measured as a function of ageing time for both heat treatment temperatures. These parameters were also related to the increase in microhardness and development of interface structure between the domains. Simulations using the dynamic Ising model show that the interfaces between the α and α′ phases should be smoother at lower ageing temperatures for a given scale of decomposition. A comparison between the experimental results and simulations is discussed.