First-principles phase diagram calculations for the HfC-TiC, ZrC-TiC and HfC-ZrC solid solutions

Published

December 10, 2009

Author(s)

Benjamin P. Burton, G. Steinle-Neumann, A, van de Walle

Abstract

We report first principles phase diagram calculations for the quasibinary systems HfC-TiC, TiC-ZrC and HfC-ZrC. Plane-wave pseudopotential methods were used to compute formation energies for superstructures of various bulk compositions, which were used as a basis for fitting cluster expansion Hamiltonians; both with- and without approximations for excess vibrational free energies, F_vib. Significant miscibility gaps are predicted for the systems TiC-ZrC and HfC-TiC, with consolute temperatures in excess of 2000 K. The HfC-ZrC system is predicted to be completely miscibile down to 185K. F_vib calculated reductions in T_C are ~20%, ~7% and ~0%, for HfC-TiC, TiC-ZrC and HfC-ZrC, respectively. Predicted miscibility gaps are: almost symmetric for HfC-TiC; asymmetric for TiC-ZrC; and symmetric for HfC-ZrC.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Volume

80

Pub Type

Journals

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Keywords

first principles, phase diagram calculation, vibrational free energy, vibrational entropy, refractory carbides, HfC, TiC, ZrC, HfC-TiC, TiC-ZrC, ZrC-TiC.

Citation

Burton, B. , Steinle-Neumann, G. , , A. and Walle, V. (2009), First-principles phase diagram calculations for the HfC-TiC, ZrC-TiC and HfC-ZrC solid solutions, Physical Review B (Condensed Matter and Materials Physics), [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=902397 (Accessed December 11, 2024)