Coarsening kinetics of γ′ precipitates in the commercial nickel base Superalloy Rene 88 DT

Rene 88 DT samples were subjected to different cooling rates after it supersolvus treatment, and aged for varying periods of time from 25 to 200 h at 760 degrees C. Primary and secondary gamma' precipitate sizes were measured after each heat treatment. Coarsening rate constants Were calculated and reported based on the measured precipitate sizes. When describing the change in radius (r) as a function of time (1). fits between the experimental results and analysis were investigated for two types Of functional relationships. r(3) vs. t and r(2) vs. I. The experimental rate constants derived front this analysis were compared with analytical values deduced front two different models: volume diffusion and bulk diffusion through the interface. The applicability of the two mechanisms for gamma' coarsening is discussed based upon the comparison between the analytically derived and experimentally observed values of these rate constants. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.