Título

First Principles Calculations of Alloy Phase Diagrams by Statistical Moment and Cluster Variation Methods

First Principles Calculations of Alloy Phase Diagrams by Statistical Moment and Cluster Variation Methods

Autoria

MASUDAJINDO, K.; HUNG, VU VAN; KIKUCHI, R.

MASUDAJINDO, K.

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HUNG, VU VAN

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KIKUCHI, R.

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DOI

10.5151/2594-5327-4115

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Resumo

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 of alloy systems are derived explicitly in closed analytic forms. The configurational entropy term is taken into account using the cluster variation method (CVM). The applications of the present combined scheme are given both for the phase separation and order-disordered alloys. For phase-separating binary alloys like CuAg and AgPd systems, the change of lattice constant with the composition and the reduction of the transition temperature are shown in detail. For the calculations of order-disordered alloys, we investigate the effects of thermal lattice vibration on the long range order (LRO) parameter and order-disorder transition temperatures. In addition, we also calculate the phase diagrams of the binary alloys like CuAg, CuAu and NiAl systems.

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 of alloy systems are derived explicitly in closed analytic forms. The configurational entropy term is taken into account using the cluster variation method (CVM). The applications of the present combined scheme are given both for the phase separation and order-disordered alloys. For phase-separating binary alloys like CuAg and AgPd systems, the change of lattice constant with the composition and the reduction of the transition temperature are shown in detail. For the calculations of order-disordered alloys, we investigate the effects of thermal lattice vibration on the long range order (LRO) parameter and order-disorder transition temperatures. In addition, we also calculate the phase diagrams of the binary alloys like CuAg, CuAu and NiAl systems.

Palavras-chave

statistical moment method, anharmonicity of thermal lattice vibration, Helmholtz free energy, grand potential order-disorder transition, cluster variation method

statistical moment method, anharmonicity of thermal lattice vibration, Helmholtz free energy, grand potential order-disorder transition, cluster variation method