Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10672457 | Ultramicroscopy | 2015 | 7 Pages |
Abstract
The evolution of phase separation and ordering processes determines the structure and properties of Ni-based superalloys. Here we use atom probe tomography to clarify the origin of γ particles occurring in ordered (L12) γⲠprecipitates in a Ni86.1Al8.5Ti5.4 alloy. Particularly, we elucidate the evolution from nanoscaled Ni-rich heterogeneities (Ni-rich clusters) to γ spheres and then γ plates inside γⲠprecipitates from the compositional and the thermodynamic point of view. We find that Ni supersaturation of γⲠprecipitates is relieved by formation of Ni-rich clusters, which results in an energetically more favorable state. Subsequently, coalescence introduces necking between the Ni-rich clusters and leads to the formation of γ particles. Our results demonstrate that phase separation of γⲠprecipitates is characterized by different stages with various governing driving forces.
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
F. Vogel, N. Wanderka, Z. Balogh, M. Ibrahim, P. Stender, G. Schmitz, T. Fedorova, J. Banhart,