Abstract
Polycrystalline nickel superallyos used in aero-engine disc applications can often possess a bimodal gamma prime microstructure, for example in NI115 and Rene 80. During heat treatment and service the gamma prime distribution can evolve, with consequent effects on the creep behaviour. Here a modified LSW coarsening model is presented to model the effect of heat treatment and service conditions on the precipitate distribution. The distribution is then used in a physically-based, phenomenological creep model, based on the work of Dyson and McLean, to predict the effect of heat treatment on the creep behaviour. The results are compared to experiment for creep tests and heat treatments performed on NI115.