Title

FIRST PRINCIPLES CALCULATIONS OF ALLOY PHASE DIAGRAMS BY COMBINED STATISTICAL MOMENT AND CLUSTER VARIATION METHODS: HIGH TEMPERATURE BCC TA-W AND MO-TA ALLOYS

FIRST PRINCIPLES CALCULATIONS OF ALLOY PHASE DIAGRAMS BY COMBINED STATISTICAL MOMENT AND CLUSTER VARIATION METHODS: HIGH TEMPERATURE BCC TA-W AND MO-TA ALLOYS

Authorship

MASUDA-JINDO, K.; HUNG, VU VAN; TURCHI, P.E.A.

MASUDA-JINDO, K.

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HUNG, VU VAN

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TURCHI, P.E.A.

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DOI

10.5151/2594-5327-2005-14336-0139

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Abstract

The thermodynamic quantities of metals and alloys are studied using the moment method in the quantum statistical mechanics, going beyond the quasi-harmonic approximations. Including the power moments of the atomic displacements up to the fourth order, the free energies and the related thermodynamic quantities are derived explicitly in closed analytic forms. The configulational entropy term is taken into account by coupling the moment expansion scheme with the cluster variation method (CVM). The melting transitions of TaW alloys are also investigated within the framework of Statistical Moment Method. The energetics of the binary (Ta-W and Mo-Ta) alloys are treated within the framework of the first-principles TB-LMTO method coupled to CPA and GPM (generalized perturbation method). The equilibrium phase diagrams are calculated for the refractory Ta-W bcc alloys.

The thermodynamic quantities of metals and alloys are studied using the moment method in the quantum statistical mechanics, going beyond the quasi-harmonic approximations. Including the power moments of the atomic displacements up to the fourth order, the free energies and the related thermodynamic quantities are derived explicitly in closed analytic forms. The configulational entropy term is taken into account by coupling the moment expansion scheme with the cluster variation method (CVM). The melting transitions of TaW alloys are also investigated within the framework of Statistical Moment Method. The energetics of the binary (Ta-W and Mo-Ta) alloys are treated within the framework of the first-principles TB-LMTO method coupled to CPA and GPM (generalized perturbation method). The equilibrium phase diagrams are calculated for the refractory Ta-W bcc alloys.

Keywords

Statistical moment method; Cluster variation method; Tight-binding LMTO; Coherent potential approximation; Alloy phase diagram; Ta-W alloy

Statistical moment method; Cluster variation method; Tight-binding LMTO; Coherent potential approximation; Alloy phase diagram; Ta-W alloy