First Principles Calculation of Phase Stability of High Temperature Intermetallic Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
J. Mikalopas ◽  
P.A. Sterne ◽  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
First Principles ◽  
Strong Dependence ◽  
Cluster Variation Method ◽  
First Principles Calculation ◽  
Variation Method ◽  
Many Body ◽  
Coherent Phase Diagram ◽  
Cluster Variation ◽  
The Many ◽  
Many Body Interactions

ABSTRACTOne way to calculate the coherent phase diagram of an alloy based on first principles methods is to compute the ground state total energy for various ordered configurations, from which many-body interactions can be calculated and employed in a thermodynamic model. If the Connolly and Williams method (CWM) is used to extract the many-body interactions from the calculated total energies, the resulting many-body interactions can exhibit a strong dependence on the choice of ordered configurations and multi-site clusters, and the accuracy and convergence of the CWM energy expansion is not assured. To overcome this difficulty, a successful systematic method for implementing the CWM is proposed. This approach is applied to a study of the fcc-based Ni-V and Pd-V substitutional alloys and these interaction parameters together with the cluster variation method (CVM) are used to calculate phase diagrams.

A First Principles Examination of Phase Stability in Fcc-Based Ni-V Substitutional Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
J. Mikalopas ◽  
P.E.A. Turchi ◽  
M. Sluiter ◽  
P.A. Sterne
Keyword(s):  
Phase Stability ◽  
Ground State ◽  
First Principles ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Many Body ◽  
Cluster Variation ◽  
Many Body Interactions ◽  
Ground State Energies ◽  
Substitutional Alloys

AbstractThe phase stability of fcc-based Ni-V substitutional alloys is investigated using linear muffin-tin orbitals total energy (LMTO) calculations. The method of Connolly and Williams (CWM) is used to extract many body interactions from the ground state energies of selected ordered configurations. These interactions are used in conjunction with the cluster variation method (CVM) to calculate the alloy phase diagram. The dependence of the interactions on the choice of configurations used to calculate them is examined.

scholarly journals Towards the First-Principles Investigation of Ordering Dynamics

2005 ◽  
Vol 475-479 ◽  
pp. 3075-3080 ◽  
Author(s):  
Tetsuo Mohri ◽  
Munekazu Ohno ◽  
Ying Chen
Keyword(s):  
First Principles ◽  
Coarse Graining ◽  
Cluster Variation Method ◽  
Field Method ◽  
Energy Functional ◽  
First Principles Calculation ◽  
Phase Field Method ◽  
Variation Method ◽  
Gradient Energy ◽  
Cluster Variation

Phase Field Method (PFM) is hybridized with Cluster Variation Method (CVM) to investigate the ordering dynamics of L10-disorder transition at atomistic and microstructural scales simultaneously. For this, coarse graining operation is attempted on the inhomogeneous free energy functional of CVM. The resultant gradient energy coefficient is found out to be dependent on temperature and order parameters, which is in marked contrast to a conventional PFM formalism. Electronic structure total energy calculations for Fe-Pd system are incorporated to the hybridized scheme and the first principles calculation of microstructural evolution process is attempted.

First-principle Thoery of Phase Stability, Phase Equilibria and Phase Transition of Ordered Compounds

2006 ◽  
Vol 980 ◽  
Author(s):  
Tetsuo Mohri
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Future Prospect ◽  
Cluster Variation Method ◽  
First Principles Calculation ◽  
Variation Method ◽  
Cluster Variation ◽  
The Stability ◽  
Noble Metal Alloys ◽  
Alloy Systems

AbstractFirst-principles theory of alloys is based on electronic structure calculation at the ground state and statistical mechanics calculation at finite temperatures. The former clarifies the stability of an ordered compound against competing phases and the latter is employed mainly to derive a phase diagram. The author performed a series of first-principles investigations on binary alloy systems including noble metal alloys, semiconductor alloys and Fe-based alloy systems by combining FLAPW electronic structure total energy calculations with Cluster Variation Method. Recently, the theoretical framework is extended even to calculate microstructural evolution process. By exemplifying Fe-based alloy systems, the progress of the first-principles calculation is reviewed and future prospect is discussed.

Thermodynamics of (Zn,Fe)S sphalerite. A CVM approach with large basis clusters

2000 ◽  
Vol 64 (5) ◽  
pp. 923-943 ◽  
Author(s):  
A. I. Balabin ◽  
R. O. Sack
Keyword(s):  
Long Range ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Nearest Neighbour ◽  
Many Body ◽  
Mean Values ◽  
Equilateral Triangles ◽  
Cluster Variation ◽  
Long Range Ordering ◽  
Many Body Interactions

AbstractWe have developed a cluster variation method (CVM) model based on cuboctahedral and octahedral basis clusters containing 13 and 6 atoms, respectively, and applied it to the analysis of the thermodynamic mixing properties of (Zn,Fe)S solid solutions. The model, in which the internal energy of the lattice is approximated by next to nearest neighbour (nnn) pair interactions and many-body interactions associated with nearest neighbour (nn) equilateral triangles, describes the FeS contents of sphalerites equilibrated with pyrrhotite and pyrite, and with pyrrhotite and iron metal within experimental uncertainties. The model predicts moderate deviations from ideality; the mean values of the Lewis and Randall activity coefficient of FeS and ZnS are, 1.48 and 1.03, respectively. Predictions of the model are in qualitative agreement with cell-edge data. The model also predicts that sphalerites undergo long-range ordering to lower-symmetry structures at temperatures only slightly below those investigated experimentally, a result in agreement with inferences from an existing Mössbauer investigation of synthetic sphalerites.More realistic models in which interactions are ascribed to larger species (nn triangular and centred square species) predict that such long-range ordering occurs at even higher temperatures and underscore the need for better characterization of the structures of (Zn,Fe)S minerals.

Accurate First Principles Calculation of Many-Body Interactions

1991 ◽  
Vol 5 (1) ◽  
pp. 57-71 ◽  
Author(s):  
Gregory J. Tawa ◽  
Jules W. Moskowitz ◽  
Paula A. Whitlock ◽  
Kevin E. Schmidt
Keyword(s):  
First Principles ◽  
First Principles Calculation ◽  
Many Body ◽  
Many Body Interactions

scholarly journals First-Principles Study of Intermetallic Phase Stability in the Ternary Ti-Al-Nb Alloy System

1994 ◽  
Vol 364 ◽  
Author(s):  
Mark Asta ◽  
Alim Ormeci ◽  
John M. Wills ◽  
Robert C. Albers
Keyword(s):  
First Principles ◽  
Intermetallic Phase ◽  
Alloy System ◽  
Cluster Variation Method ◽  
Ternary Alloys ◽  
Interaction Parameters ◽  
Variation Method ◽  
Cluster Variation ◽  
The Stability ◽  
Alloy Thermodynamic

AbstractThe stability of bcc-based phases in the Ti-Al-Nb alloy system has been studied from first-principles using a combination of ab-initio total energy and cluster variation method (CVM) calculations. Total energies have been computed for 18 binary and ternary bcc superstructures in order to determine low temperature ordering tendencies. From the results of these calculations a set of effective cluster interaction parameters have been derived. These interaction parameters are required input for CVM computations of alloy thermodynamic properties. The CVM has been used to study the effect of composition on finite-temperature ordering tendencies and site preferences for bcc-based phases. Strong ordering tendencies are observed for binary Nb-Al and Ti-Al bcc phases as well as for ternary alloys with compositions near Ti2AlNb. For selected superstructures we have also analyzed structural stabilities with respect to tetragonal distortions which transform the bcc into an fcc lattice. Instabilities with respect to such distortions are found to exist for binary but not ternary bcc compounds.

First-Principles Theory of Alloy Phase Diagrams

1988 ◽  
Vol 141 ◽  
Author(s):  
Alex Zunger ◽  
L. G. Ferreira ◽  
S.-H. Wei
Keyword(s):  
Phase Diagrams ◽  
First Principles ◽  
Low Temperatures ◽  
Local Density ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Interaction Energies ◽  
Ordered Structures ◽  
Cluster Variation ◽  
Dependent Interaction

AbstractTemperature-composition phase diagrams of alloys are calculated by a new method combining (i) first principles total energy calculations (at T=0) for ordered structures, using the local density formalism, with (ii) finite-temperature statistical-mechanics approach (the Cluster Variation Method) to the solution of the multi-spin Ising model, using volume-dependent interaction energies obtained from (i). Novel features, including the appearance of metastable long-range ordered compounds at low temperatures are discovered.

scholarly journals A First-Principles Study of the Phase Stability of FCC-Based Ti-Al Alloys

1992 ◽  
Vol 278 ◽  
Author(s):  
Mark Asta ◽  
Didier De Fontaine ◽  
Mark Van Schilfgaarde ◽  
Marcel Sluiter ◽  
Michael Methfessel
Keyword(s):  
Phase Stability ◽  
First Principles ◽  
Cluster Variation Method ◽  
Stability Study ◽  
Al Alloys ◽  
Variation Method ◽  
Orbital Method ◽  
Temperature Phase ◽  
Full Potential ◽  
Cluster Variation

AbstractIn this paper we present results of a first-principles phase stability study of fcc-based Ti-Al alloys. In particular, the full-potential linear muffin tin orbital method has been used to determine heats of formation and other zero-temperature properties of 9 fcc ordered superstructures as well as fcc and hcp Ti, and fcc Al. From these results a set of effective cluster interactions are determined which are used in a cluster variation method calculation of the thermodynamic properties and the composition-temperature phase diagram of fcc-based alloys.

First-principles study of phase stability of Ti–Al intermetallic compounds

1993 ◽  
Vol 8 (10) ◽  
pp. 2554-2568 ◽  
Author(s):  
Mark Asta ◽  
Didier de Fontaine ◽  
Mark van Schilfgaarde
Keyword(s):  
Intermetallic Compounds ◽  
Phase Stability ◽  
First Principles ◽  
Experimental Studies ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Orbital Method ◽  
Temperature Phase ◽  
Full Potential ◽  
Cluster Variation

Thermodynamic and structural properties of fcc- and hcp-based Ti–Al alloys are calculated from first-principles and are used to perform an ab initio study of phase stability for the intermetallic compounds in this system. The full potential linear muffin tin orbital method is used to determine heats of formation and other zero-temperature properties of 9 fcc- and 7 hcp-based intermetallic compounds, as well as of elemental fcc and hcp Ti and Al. From the results of these calculations, sets of effective cluster interactions are derived and are used in a cluster variation method calculation of the solid-state portion of the composition-temperature phase diagram for fcc- and hcp-based alloy phases. The results of our calculations are compared with those of experimental studies of stable and metastable phases in the Ti–Al system.

Sign in / Sign up

Export Citation Format

Share Document