SKM 2023 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 36: Data Driven Materials Science: Big Data and Work Flows – Microstructure-Property-Relationships (joint session MM/CPP)

MM 36.8: Talk

Thursday, March 30, 2023, 12:15–12:30, SCH A 251

Accurate thermodynamic properties of bcc refractories through Direct Upsamling — •Axel Forslund, Jong Hyun Jung, Prashanth Srinivasan, and Blazej Grabowski — Institute for Materials Science, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart

The outstanding high-temperature properties of the bcc refractory elements make them important in many industrial and scientific applications. Accurate thermodynamic data of unary bcc refractories are a requisite, for example, when used as end members for phase diagrams of high entropy alloys. In this work, we have calculated thermodynamic properties of the four bcc refractory elements V, Ta, Mo and W up to the melting point with full DFT accuracy with the newly developed Direct Upsampling method. We present highly converged Gibbs energy surfaces, from which accurate temperature dependence of heat capacity, thermal expansion coefficient and bulk modulus can be derived. We show their convergence with respect to fitting polynomial order and volume-temperature-grid density. Some group trends are observed, related to the electronic densities of states. In our analysis, we also estimate the contribution from thermal vacancies based on a single high-temperature calculation of the vacancy formation free energy. Further, our results are analysed in terms of homologous temperature for the elements of which a theoretical melting point (connected to the specific exchange correlation functional used) is known. The homologous temperature dependence of the calculated properties show a remarkable agreement with experiments.