### Abstract

An integrative approach coupling first-principles calculations and the CALculation of PHAse Diagram (CALPHAD) method provides a more thermodynamically accurate model of the Hf-W system when compared to previous models. A two-sublattice model is used for describing the solid solubility of the HfW _{2} Laves phase. The modeling of the Laves phase includes input from first-principles total energy calculations and predictions of finite temperature properties from the Debye-Grüneisen model. In addition, first-principles calculations performed on hcp and bcc special quasirandom structures (SQS) predicted a positive enthalpy of mixing in both solid solution phases. Predicting the finite temperature properties of bcc SQS with the Debye-Grüneisen model was necessary to balance the positive, asymmetric enthalpy of mixing found in the bcc solid solution. The model produced by the coupling of CALPHAD modeling with first-principles calculations agrees well with experimental data. It also reproduces the Hf-W phase diagram with fewer parameters than previous models, which were created without the aid of first-principles calculations.

Original language | English (US) |
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Pages (from-to) | 92-99 |

Number of pages | 8 |

Journal | Calphad: Computer Coupling of Phase Diagrams and Thermochemistry |

Volume | 38 |

DOIs | |

State | Published - Sep 1 2012 |

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### All Science Journal Classification (ASJC) codes

- Chemistry(all)
- Chemical Engineering(all)
- Computer Science Applications

### Cite this

*Calphad: Computer Coupling of Phase Diagrams and Thermochemistry*,

*38*, 92-99. https://doi.org/10.1016/j.calphad.2012.04.005