| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond V
|
| Presentation Title |
The Role of Enthalpy, Configurational Entropy, and Vibrational Entropy in Mixing Ultrahigh Temperature Ceramics |
| Author(s) |
Xiaochuan Tang, Gregory Thompson, Christopher R. Weinberger |
| On-Site Speaker (Planned) |
Christopher R. Weinberger |
| Abstract Scope |
One area of application of high entropy materials is in ultrahigh temperature ceramics. Two main classes of these materials are transition metal carbides, with the rocksalt structure, and the transition metal diborides, with the AlB2 structure. However, there are gaps in our understanding of the thermodynamics of mixing of these complicated compounds. Thus, to explore how these materials might mix and what affects their mixing, we have utilized density functional theory calculations to determine the enthalpies of mixing, coupled with the quasi-harmonic approximation to obtain finite temperature free energies. These calculations elucidate the roles of atomic mismatch on enthalpies of formation and the competition between enthalpy, configurational entropy and vibrational entropy – all of which dominate in some regimes of composition and temperature space. These calculations and insights allow us to predict utilize the CALPHAD method to predict phase diagrams and temperatures for pure solid solutions. |