Phase-field modeling of bimodal microstructures in nickel-based superalloys

✍ Scribed by G. Boussinot; A. Finel; Y. Le Bouar

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 420 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.10.039

✦ Synopsis

The phase-field approach is used to study the formation and ageing of bimodal microstructures in a model Ni-based superalloy. Particular attention is paid to the definition of interfacial energies in the presence of elastic strain fields and to the incorporation of these energies in the phase-field formalism. During a two-step annealing procedure, our model predicts the formation of large anisotropic c 0 precipitates (called secondary precipitates) and small, almost isotropic c 0 precipitates (called tertiary precipitates). Finally, the phase-field model is used to characterize the ageing of tertiary precipitates. In agreement with experiments, we show that the mean size of the tertiary precipitates first grows as t 1=3 and finally reaches a plateau. This peculiar behavior is explained using phase-field simulations with prescribed geometries and with the development of a simple analytic model.