Long term coarsening of γ′ precipitates in a Ni-base superalloy

The mechanical properties of a Ni-based superalloy strongly depend on the distribution and size of the precipitate particle γ′ phase: Ni3(Al, Ti). Such particles grow during the initial heat treatment and it is very important to predict the kinetic growth owing to their technological application at high temperatures. In this work, we performed analysis of particle coarsening in IN-713C during long ageing times at constant temperature, given an initial size and volume fraction distribution of the γ′ precipitate phase, and the evaluation of two different heat treatments through the microstructure analysis and γ′ morphology. We found that for short ageing times, t < 2500 h, the coarsening can be approximated by a linear volumetric growth as predicted by Lifshitz, Slyozov and Wagner (LSW) theory. For a time greater than 2500 h the growth rate of γ′ precipitate shows an asymptotic behaviour in both heat treatments.