Coarsening of coherent precipitates γ′ in alloys such as Ni-based alloys has been studied extensively not only for its practical significance in the design of engineering alloys but also in an effort to understand the phenomenon of coarsening. However, a complete understanding of the role of the multiple factors that can affect the coarsening kinetics in such systems is still lacking. Although some advances have been made through computer simulations, studying experimentally the influence of the volume fraction of the second phase and that of coherency strains on the kinetics of coarsening has been particularly challenging. This paper will highlight some of the issues that are relevant to the study of coarsening in multi-component alloy systems. Recent results obtained for the kinetics of coarsening of γ′ precipitates in different alloys within the Ni-Al-Si system will be presented. Compositions of these alloys have been chosen so as to vary both the magnitude and the sign of coherency strains between the precipitate and the matrix. Some anomalies related to the composition dependence of the kinetics of coarsening will be highlighted. This paper will conclude with a discussion on the role of the volume fraction of the second phase and coherency strains in contributing to these anomalies and identify directions for future work.
- Coarsening kinetics
- Coherency strains
- Intermetallic compounds
- Ni-based superalloys
- Small-angle neutron scattering