Analysis of the precipitation process of the intermetallic phases in a high-temperature Fe–Ni austenitic alloy

The influence of prolonged ageing on the precipitation process of the intermetallic phases and carbides in a high-temperature austenitic Fe–Ni alloy has been studied. The samples were subjected to a solution heat treatment at 980 °C for 1 h and water quenched, and then aged at 715 °C for 0.5–500 h. The samples were analysed using transmission electron microscopy (TEM) and X-ray diffraction. Direct measurements on the electron micrographs allowed to calculate the structural parameters of the γ′ phase: mean diameter, volume fraction, and mean distance between the particles.