Thermodynamic properties of Laves phases in the Mg-Al-Ca system at finite temperature from first-principles

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Abstract

First-principles calculations are employed to investigate the structural and thermodynamic properties of binary Laves phases (C14, C15 and C36 structures) in the Mg-Al-Ca system. The enthalpies of formation at 0 K are predicted. The vibrational contributions to Helmholtz free energy for the stable C14-Mg 2Ca and C15-Al 2Ca phases are determined using both first-principles phonon calculations and Debye-Grüneisen model. The predicted thermodynamic properties of the stable phases, including enthalpy, entropy, bulk modulus, heat capacity, and thermal expansion coefficient, agree well with available experimental data. For the other nonstable phases, the thermodynamic properties are estimated by Debye-Grüneisen models of Moruzzi et al. and of Wang et al. The entropies predicted from these two Debye models have a general agreement with about ±0.5 J/mol K differences for all the three structures.

Original languageEnglish (US)
Pages (from-to)17-23
Number of pages7
JournalIntermetallics
Volume22
DOIs
StatePublished - Mar 1 2012

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Thermodynamic properties
Enthalpy
Entropy
Temperature
Free energy
Specific heat
Thermal expansion
Structural properties
Elastic moduli

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

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title = "Thermodynamic properties of Laves phases in the Mg-Al-Ca system at finite temperature from first-principles",
abstract = "First-principles calculations are employed to investigate the structural and thermodynamic properties of binary Laves phases (C14, C15 and C36 structures) in the Mg-Al-Ca system. The enthalpies of formation at 0 K are predicted. The vibrational contributions to Helmholtz free energy for the stable C14-Mg 2Ca and C15-Al 2Ca phases are determined using both first-principles phonon calculations and Debye-Gr{\"u}neisen model. The predicted thermodynamic properties of the stable phases, including enthalpy, entropy, bulk modulus, heat capacity, and thermal expansion coefficient, agree well with available experimental data. For the other nonstable phases, the thermodynamic properties are estimated by Debye-Gr{\"u}neisen models of Moruzzi et al. and of Wang et al. The entropies predicted from these two Debye models have a general agreement with about ±0.5 J/mol K differences for all the three structures.",
author = "Hui Zhang and Shunli Shang and Yi Wang and Long-qing Chen and Zi-kui Liu",
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T1 - Thermodynamic properties of Laves phases in the Mg-Al-Ca system at finite temperature from first-principles

AU - Zhang, Hui

AU - Shang, Shunli

AU - Wang, Yi

AU - Chen, Long-qing

AU - Liu, Zi-kui

PY - 2012/3/1

Y1 - 2012/3/1

N2 - First-principles calculations are employed to investigate the structural and thermodynamic properties of binary Laves phases (C14, C15 and C36 structures) in the Mg-Al-Ca system. The enthalpies of formation at 0 K are predicted. The vibrational contributions to Helmholtz free energy for the stable C14-Mg 2Ca and C15-Al 2Ca phases are determined using both first-principles phonon calculations and Debye-Grüneisen model. The predicted thermodynamic properties of the stable phases, including enthalpy, entropy, bulk modulus, heat capacity, and thermal expansion coefficient, agree well with available experimental data. For the other nonstable phases, the thermodynamic properties are estimated by Debye-Grüneisen models of Moruzzi et al. and of Wang et al. The entropies predicted from these two Debye models have a general agreement with about ±0.5 J/mol K differences for all the three structures.

AB - First-principles calculations are employed to investigate the structural and thermodynamic properties of binary Laves phases (C14, C15 and C36 structures) in the Mg-Al-Ca system. The enthalpies of formation at 0 K are predicted. The vibrational contributions to Helmholtz free energy for the stable C14-Mg 2Ca and C15-Al 2Ca phases are determined using both first-principles phonon calculations and Debye-Grüneisen model. The predicted thermodynamic properties of the stable phases, including enthalpy, entropy, bulk modulus, heat capacity, and thermal expansion coefficient, agree well with available experimental data. For the other nonstable phases, the thermodynamic properties are estimated by Debye-Grüneisen models of Moruzzi et al. and of Wang et al. The entropies predicted from these two Debye models have a general agreement with about ±0.5 J/mol K differences for all the three structures.

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