LONG-TERM COARSENING OF GAMMA' 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 gamma' phase: Ni -3(Al, Ti). Such particles grow during the initial heat treatment and it is very important to predict the kinetic growth owing to their tech nological application at high temperatures. In this work, we performed analysis of particle coarsening in IN-713C during long ageing times a t constant temperature, given an initial size and volume fraction dist ribution of the gamma' precipitate phase, and the evaluation of two di fferent heat treatments through the microstructure analysis and gamma' morphology. We found that for short ageing times, t < 2500 h, the coa rsening 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 gamma' precipitate shows an asymptotic beha viour in both heat treatments.