Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10620171 | Acta Materialia | 2013 | 11 Pages |
Abstract
The expeditious development of novel cobalt-base γ-γⲠalloys as possible next generation superalloys critically depends on achieving a comprehensive understanding of the coarsening kinetics of ordered γⲠprecipitates. This paper discusses the coarsening of L12 ordered Co3(W, Al) precipitates in a model ternary Co-10Al-10W (at.%) alloy during isothermal annealing at 800 and 900 °C. The experimentally determined temporal evolution of average size of the γⲠprecipitates suggests classical matrix diffusion limited Lifshitz-Slyozov-Wagner coarsening at both temperatures. The γⲠcoarsening rate constants have been determined using a modified coarsening rate equation for non-dilute solutions. Furthermore, using the Cahn-Hilliard formulation for interfacial energy, the γ/γⲠinterfacial energies at the respective annealing temperatures have been correlated to the concentration profile across the interface that has been experimentally determined using atom probe tomography. The calculated interfacial energies are in comparable range with those observed in nickel-base superalloys. Additionally, this analysis has permitted, for the first time, the determination of the gradient energy coefficient for γ/γⲠinterfaces in Co-base alloys, a critical input for phase-field and other simulation models for microstructural evolution.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
S. Meher, S. Nag, J. Tiley, A. Goel, R. Banerjee,