Enthalpies of formation of liquid binary (copper + iron, cobalt, and nickel) alloys
- National Univ. of Lesotho (South Africa). Dept. of Chemistry
- Donbass State Mechanical Engineering Academy, Kramatorsk (Ukraine). Dept. of Technology and Apparatuses of Cast Manufacture
The enthalpies of formation of liquid binary (Cu + Fe, Co, Ni) alloys are studied by direct reaction calorimetry in the whole range of compositions at 1873, 1823, and 1753 K, respectively. The integral molar enthalpies of mixing are found to be positive in all three systems with the maximum values approaching 10.8 {+-} 0.7 kJ/mol{sup {minus}1} at x{sub Fe} = 0.43, 7.1 {+-} 0.9 kJ/mol{sup {minus}1} at x{sub Co} = 0.55, and 3.7 {+-} 0.5 kJ/mol{sup {minus}1} at x{sub Ni} = 0.53. Partial molar enthalpies at infinite dilution constitute 59.4 {+-} 3.3 kJ/mol{sup {minus}1} for iron, 44.3 {+-} 4.1 kJ/mol{sup {minus}1} for cobalt, and 14.9 {+-} 2.2 kJ/mol{sup {minus}1} for nickel in liquid copper. Similar values for copper in liquid iron, cobalt, and nickel are 36.6 {+-} 3.9, 45.3 {+-} 6.0, and 17.7 {+-} 4.4 kJ/mol{sup {minus}1}, respectively. The results are compared with the thermodynamic data available in literature and discussed in connection to the equilibrium-phase diagrams. In particular, decreasing from Cu-Fe to Cu-Ni liquid alloys positive values of the excess thermodynamic functions of mixing are fully in accord with the growing stability of phases in these systems. The excess entropies of mixing are estimated by combining the established enthalpies with carefully selected literature data for the excess Gibbs functions. Analysis of possible contributions to the enthalpies of mixing indicates that the experimentally established regularity in {Delta}H values along the 3d series is likely to arise from the difference in d-band width and d-electron binding energy of the alloy constituents.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 585994
- Journal Information:
- Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science, Vol. 28, Issue 6; Other Information: PBD: Dec 1997
- Country of Publication:
- United States
- Language:
- English
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