The direct Monte Carlo method for calculating alloy phases

Conference · Sun Nov 01 00:00:00 EST 1992

OSTI ID:10180433

Faulkner, J S; Horvath, E A; Wang, Yang ^[1]; Stocks, G M ^[2]

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1. Florida Atlantic Univ., Boca Raton, FL (United States)
2. Oak Ridge National Lab., TN (United States)

Theories exist for predicting the structure of an alloy on the assumption that the energy of the alloy can be obtained from an Ising model Hamiltonian. It is not necessary to introduce interatomic potentials if the Monte Carlo method is used for thermodynamics. {delta}H is calculated directly from the electronic structure of the alloy using the embedded cluster method (ECM) of alloy theory. ECM is based on the coherent potential approximation (CPA) for the electronic states of random substitutional alloys. A version of the theory was developed within the context of the tight-binding model. Cray ymp calculations were made for a 50 - 50 Pd - Rh fcc alloy; electronic energies were obtained using an ECM based on KKR-CPA programs. The top of the miscibility gap is predicted to be at 1415 K. The order parameter vs T graph shows a critical temperature just above 1200 K. Calculations in the grand canonical mode are underway. The calculations are for the fcc lattice, but the bcc lattice is also considered. There are other methods, such as the Harris approximation, that will improve the energy calculations. 4 figs, 15 refs. (DLC)

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400; FG05-89ER45392
• OSTI ID: 10180433
• Report Number(s): CONF-9206202-2; ON: DE93000436
• Resource Relation: Conference: NATO advanced study institute on statics and dynamics of alloy phase transformations,Rhodes (Greece),21 Jun - 3 Jul 1992; Other Information: PBD: [1992]
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
MONTE CARLO METHOD
PHASE DIAGRAMS
PALLADIUM ALLOYS
RHODIUM ALLOYS
ISING MODEL
HAMILTONIANS
ENERGY
ELECTRONIC STRUCTURE
TEMPERATURE RANGE 1000-4000 K
FCC LATTICES
BCC LATTICES
BINARY ALLOY SYSTEMS
360102
665000
STRUCTURE AND PHASE STUDIES
PHYSICS OF CONDENSED MATTER