Using first-principles results to calculate finite-temperature thermodynamic properties of the Nb-Ni mu phase in the Bragg-Williams approximation
2006 (English)In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 86, no 12, 1631-1641 p.Article in journal (Refereed) Published
Results of first-principles (FP) total energy calculations for 32 different configurations of the mu phase in the binary system Nb-Ni are used in the compound energy formalism (CEF) to model finite-temperature thermodynamic properties. A comparison with Cluster Expansion Hamiltonian-Cluster Variation Method (CEH-CVM) calculations indicates that the CEF describes temperature-dependent site occupancies as well as the CEH-CVM within the temperature range of interest for applications. This suggests that the Bragg-Williams-Gorsky approximation (BWGA) used in the CEF is sufficient to describe site occupancies and thermodynamics of the mu phase. A phase diagram is calculated using the mu phase description derived in the present work together with a previous Calphad description for the other phases of this system. The FP-CEF approach significantly improves the description of the thermodynamic properties as a function of composition compared to the Calphad procedure generally used up to now.
Place, publisher, year, edition, pages
2006. Vol. 86, no 12, 1631-1641 p.
configurational heat-capacity, composition-dependence, system, alloys, equilibria, calphad
IdentifiersURN: urn:nbn:se:kth:diva-15640DOI: 10.1080/14786430500437488ISI: 000237083900002ScopusID: 2-s2.0-33646518858OAI: oai:DiVA.org:kth-15640DiVA: diva2:333682
QC 201005252010-08-052010-08-05Bibliographically approved