TY - JOUR

T1 - First-principles calculations and thermodynamic re-modeling of the Hf-W system

AU - Lieser, Alyson C.

AU - Zacherl, Chelsey L.

AU - Saengdeejing, Arkapol

AU - Liu, Zi Kui

AU - Kecskes, Laszlo J.

N1 - Funding Information:
The financial support from U.S. Army Research Laboratory under contract W911NF-08-2-0064 is greatly appreciated. First-principles calculations for this work were carried out on the LION clusters at the Pennsylvania State University supported by the Materials Simulation Center and the Research and Computing Cyberinfrastructure and in part through instrumentation funded by the National Science foundation grant OCI-0821527 . The authors would like to thank Dr. Shun-Li Shang for the use of his scripts.

PY - 2012/9

Y1 - 2012/9

N2 - 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.

AB - 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.

KW - Debye-Grüneisen model

KW - First-principles calculations

KW - Hafnium

KW - Special quasirandom structures

KW - Thermodynamic modeling

KW - Tungsten alloys

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U2 - 10.1016/j.calphad.2012.04.005

DO - 10.1016/j.calphad.2012.04.005

M3 - Article

AN - SCOPUS:84862509484

VL - 38

SP - 92

EP - 99

JO - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry

JF - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry

SN - 0364-5916

ER -