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A systematic DFT-based analysis of binary phase diagrams in the Bragg-Williams approximation

Mauro Palumbo, Ruhr-Universität Bochum, Bochum, Germany

Jörg Koßmann, Ruhr-Universität Bochum, Bochum, Germany

Gabriele Cacciamani, University of Genoa, Genoa, Italy

Suzana Fries, Ruhr-Universität Bochum, Bochum, Germany

Thomas Hammerschmidt, Ruhr-Universität Bochum, Bochum, Germany

Time & Place
  • Date: 07.09.2014
  • Time:
  • Place: TOFA 2014, Brno, Czech Republik

Abstract

DFT calculations of the enthalpy of formation have become a standard method in materials science and they are widely applied in CALPHAD modelling of phase diagrams. A CALPHAD assessment can benefit in many ways from using DFT results, as shown for example in some recent works1-3.

In this work we have systematically analysed several binary systems of interest for Ni- and Co-based superalloys, using DFT calculations at 0 K. Using a simple Bragg-Williams approximation, we have computed temperature-dependent stable and metastable phase diagrams without fitting parameters. We discuss features of experimental phase diagrams which are captured in our approach but also potential pitfalls, including the effect of computational settings on the final results4. We also discuss benefits for thermodynamic modelling of metastable phases.

This work is part of the collaborative research center SFB/TR 103.

References:

1. M. Palumbo, T. Abe, C. Kocer, H. Murakami, H. Onodera, CALPHAD, 34 (2010) 494
2. M. Palumbo, L. Battezzati, A. Pasturel, S. Gottlieb-Schönmeyer, W. Assmus, CALPHAD 33 (2009) 511-516
3. G. Cacciamani, A. Dinsdale, M. Palumbo, A. Pasturel, Intermetallics 18, 6 (2010) 1148
4. M. Palumbo, S. G. Fries, T. Hammerschmidt, T. Abe, J.-C. Crivello, A. Breidi, J-.M. Joubert, R. Drautz, Computational Materials Science, 81 (2014) 433

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