| About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Continuous Phase Transformations
|
| Presentation Title |
Cluster Variation Model of Phase Behavior in Heusler-forming Alloy Systems |
| Author(s) |
Michael Widom |
| On-Site Speaker (Planned) |
Michael Widom |
| Abstract Scope |
Energetics of chemical order in many alloys may be approximated by simple model Hamiltonians containing “clusters” of atoms. Each cluster contributes a certain energy that that can be fit to first principles calculations. The Cluster Variation Method represents the entropy in terms these clusters, and then varies cluster frequencies to minimize the free energy. This type of generalized mean field theory is convenient for exploring complex alloy phase diagrams. We apply the method to analyze phase transformation pathways in the family of Heusler compounds. The Heusler structure arises from a sequence of symmetry-breaking chemical ordering transitions on a body-centered cubic lattice, eventually leading to a set of four interpenetrating simple cubic sublattices; a total of eight distinct structures interpolate between the fully disordered BCC phase and the fully ordered quaternary Heusler. We discuss specific cluster-based models to represent specific phases and their transformations in several Heusler-forming compounds. |
| Proceedings Inclusion? |
Planned: |