Phase Diagram of Ni-Pt from Linear Muffin-Tin Orbitals Total Energy Calculations

1991 ◽  
Vol 253 ◽  
Author(s):  
C. Amador ◽  
W. R. L. Lambrecht ◽  
B. Segall
Keyword(s):  
Phase Diagram ◽  
Effective Interaction ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Ordered Structures ◽  
Atomic Sphere ◽  
Sphere Approximation ◽  
Total Energies ◽  
The Difference ◽  
Cluster Variation

ABSTRACTProgress in the calculation of the phase diagram of the Ni-Pt compounds from "first-principles" is reported. Our procedure consists of: (1) calculating total energies for ordered structures as a function of volume and including internal relaxations by means of the linear muffin-tin orbitals method within the atomic sphere approximation; (2) mapping these results onto an Ising model with effective interaction parameters; and (3) calculating the phase diagram by means of the cluster variation method. We identify the elastic energy related to the difference in the Ni and Pt lattice constant as one of the major problems in this system and discuss the convergence of the cluster expansion of the energy.

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.

Glass Transition within the Cluster Variation Approximation

2007 ◽  
Vol 26-28 ◽  
pp. 723-726
Author(s):  
Tetsuo Mohri
Keyword(s):  
Phase Diagram ◽  
Free Energy ◽  
Glass Transition ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Cluster Variation ◽  
Ordering Transition ◽  
Limiting Case ◽  
The Ideal

The detailed behavior of the free energy of Cluster Variation Method in the vicinity of spinodal ordering transition is examined. The generalized phase diagram proposed in the previous study is modified and spinodal ordering transition is reinterpreted as a limiting case of the ideal glass transition.

LMTO/CVM and LAPW/CVM Calculations of the Nial-Niti Pseudobinary Phase Diagram

1990 ◽  
Vol 213 ◽  
Author(s):  
Benjamin P. Burton ◽  
Jean E. Osburn ◽  
Alain Pasturel
Keyword(s):  
Nearest Neighbor ◽  
Equations Of State ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Two Phase ◽  
Pairwise Interactions ◽  
Phase Fields ◽  
Pseudobinary Phase Diagram ◽  
Total Energies ◽  
Cluster Variation

ABSTRACTLinear Muffin Tin Orbital and Linearly Augmented Plane Wave calculations of equations of state were performed for observed and hypothetical ordered structures in the NiAl-NiTi system. Total energies were parameterized in both the Connolly-Williams and ∈-G approximations, and the resulting parameters were used to calculate theoretical phase diagrams by the cluster variation method. Third nearest neighbor Al-Ti pairwise interactions are predicted to be strongly repulsive, and to be a major cause of observed B2+L21 two phase fields.

Phase Stabilities in Some B2 Type Ordered Ni-Al-X Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
Tetsumori Shinoda ◽  
Y. Mishima ◽  
T. Suzuki
Keyword(s):  
Free Energy ◽  
Chemical Potential ◽  
Cluster Variation Method ◽  
Phase Region ◽  
Variation Method ◽  
Isothermal Phase Diagram ◽  
B2 Phase ◽  
The Difference ◽  
Cluster Variation ◽  
Ordered State

AbstractThe difference in developing of solubility lobe (s.l.) of B2 phase from the B2 NiAl point on each isothermal phase diagram of Ni-Al-Co, Ni-Al-Fe and Ni-Al-Mn is expected to be explained in terms of the pattern of free energy minimum (f.e.m.) line in the B2 phase region of these phase diagrams. To calculate such the f.e.m. line, a simple way has been proposed based on the tetrahedron approximation of the cluster variation method (CVM) making use of a relationship to correlate the conventional chemical potential of a species with some kinds of the CVM variables. The calculated results show that the f.e.m. line well reflects the solubility lobe developing of the B2 phase for both Ni-Al-Fe and Ni-Al-Co while some disagreement arises with Ni-Al-Mn. The results also show a theoretical possibility of transition from the high ordered state B2 to a low ordered one under a relatively low temperature regime so far as the present free energy model are concerned.

Modeling of Antiphase Boundaries in L12 Structures

1986 ◽  
Vol 81 ◽  
Author(s):  
J.M. Sanchez ◽  
S. Eng ◽  
Y.P. Wu ◽  
J.K. Tien
Keyword(s):  
Antiphase Boundary ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Bulk Alloy ◽  
Antiphase Boundaries ◽  
Ordered Structures ◽  
Wetting Transitions ◽  
Ordered Alloys ◽  
Disordered Layer ◽  
Cluster Variation

AbstractThe thermodynamic properties of conservative (111) antiphase boundaries in L12 ordered structures are modeled using the tetrahedron approximation of the cluster variation method. The concentration and long-range order parameter profiles are determined as a function of temperature and composition of the bulk alloy. Characteristic wetting transitions, with a macroscopic disordered layer growing from the antiphase boundary as the transition temperature is approached, are found for all cases investigated. The effectof antiphase boundaries on the disordering of ordered alloys and on the gliding of superdislocations are discussed.

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