Thermodynamics Research Center / ThermoML | Thermochimica Acta

Thermodynamic modeling of the Co Hf system supported by key experiments and first-principles calculations

Lu, X.[Xingxu], Liu, S.[Shuhong], Cheng, K.[Kaiming], Tang, Y.[Ying], Ou, P.[Pengfei], Nash, P.[Philip], Sundman, B.[Bo], Du, Y.[Yong], Zheng, F.[Feng]
Thermochim. Acta 2015, 608, 49-58
ABSTRACT
Phase equilibria and thermodynamic properties of the Co Hf system were investigated via calorimetric measurements, first-principles calculations and thermodynamic modeling. Heat contents of Co2Hf and CoHf2 were measured by drop calorimetry from 300 to 1200 C. The enthalpy of formation for Co23Hf6 at 0 K was computed via first-principles calculations. Based on the experimental measurements and firstprinciples calculations from the present work and the literature, the Co Hf system was assessed by means of CALPHAD (CALculation of PHAse Diagram) approach. The excess Gibbs energy of solution phases was modeled with Redlich Kister polynomial. Sublattice models were employed to describe the homogeneity ranges of Co2Hf, CoHf and CoHf2. The order disorder transition between B2 (CoHf) and A2 (bHf) phases was taken into account in the current optimization. Using the optimized parameters, glass forming range (GFR) of the Co Hf amorphous alloys was predicted to be 15 75 at.% Hf, which is in satisfactory agreement with the experimental observation.
Compounds
# Formula Name
1 Co cobalt
2 Hf hafnium
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • 2
  • Molar enthalpy, kJ/mol ; Crystal of intercomponent compound 1
  • Temperature, K; Crystal of intercomponent compound 1
  • Pressure, kPa; Crystal of intercomponent compound 1
  • Mole fraction - 2; Crystal of intercomponent compound 1
  • Crystal of intercomponent compound 1
  • Drop calorimetry
  • 10
  • POMD
  • 1
  • 2
  • Molar enthalpy, kJ/mol ; Crystal of intercomponent compound 2
  • Temperature, K; Crystal of intercomponent compound 2
  • Pressure, kPa; Crystal of intercomponent compound 2
  • Mole fraction - 2; Crystal of intercomponent compound 2
  • Crystal of intercomponent compound 2
  • Drop calorimetry
  • 10