Modelling the nucleation, growth and coarsening kinetics of γ (D022) precipitates in the Ni-base Alloy 625

Alloy 625 is susceptible to significant precipitation hardening through the formation of gamma '' (D0(22)-NbNi3) particles. These precipitates can form both during manufacture and in high temperature service and, consequently, the accurate prediction of their behaviour is crucial. To this end, a model is presented here which describes gamma '' precipitation in Alloy 625, encompassing the concurrent nucleation, growth and coarsening of different particles and allowing for the particles to be shape changing. This model is calibrated with respect to the experimentally measured aspect ratio evolution observed at 650 degrees C. The resultant outputs for interfacial energy, particle size distribution and number density are in agreement with experimental data for a simulation of 1000 h at 650 degrees C. Crown Copyright (C) 2016 Published by Elsevier Ltd on behalf of Acta Materialia Inc. All rights reserved.