Electronic Structure and Phase Stability Properties of Ai-Li Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
Antonios Gonis ◽  
Patrice E.A. Turchi ◽  
Marcel Sluiter ◽  
Frank J. Pinski ◽  
Duane D. Johnson
Keyword(s):  
Phase Diagram ◽  
Electronic Structure ◽  
Perturbation Method ◽  
Multiple Scattering ◽  
Phase Stability ◽  
First Principles ◽  
Potential Approximation ◽  
Effective Interactions ◽  
Lattice Constants ◽  
Effective Cluster

AbstractRecently, the phase diagram of AI-Li alloys was calculated with the use of the Connolly-Williams method. In an effort to test the validity and to supplement the results of that study, equilibrium lattice constants and effective cluster interactions have been obtained using the generalized perturbation method within the first-principles multiple-scattering formalism of the Korringa-Kohn-Rostoker coherent-potential approximation. The implication of these effective interactions to the phase stability of these alloys is discussed.

A Comparative First Principles Study of Phase Stability in Ni-Ti and Ni-Al Alloys Around Equiatomic Composition

1990 ◽  
Vol 186 ◽  
Author(s):  
P.E.A. Turchi ◽  
M. Sluiter ◽  
F.J. Pinski ◽  
D.D. Johnson
Keyword(s):  
Electronic Structure ◽  
Internal Energy ◽  
Phase Stability ◽  
First Principles ◽  
Al Alloys ◽  
Equiatomic Composition ◽  
Potential Approximation ◽  
Dependent Part ◽  
Substitutional Alloys ◽  
Effective Cluster

AbstractElectronic structure and phase stability properties of Ni-Ti and Ni-Al around equiatomic composition are investigated with a first principles approach. The study is based upon the generalized purturbation method applied to the Korringa-Kohn-Rostoker multiple scattering formulation of the coherent potential approximation. Within this framework, effective cluster interactions which build up the configuration-dependent part of the internal energy are calculated. The strength of ordering tendencies in both bcc-based substitutional alloys is compared and contrasted in terms of hybridisation effects, in relation with experimental evidences.

First-Principles Study of Phase Stability in Pd-Rh Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
D.D. Johnson ◽  
P.E.A. Turchi ◽  
Marcel Sluiter ◽  
D.M. Nicholson ◽  
F.J. Pinski ◽  
...  
Keyword(s):  
Phase Separation ◽  
Phase Stability ◽  
First Principles ◽  
Ternary Addition ◽  
Potential Approximation ◽  
Effective Interactions ◽  
Reference Medium ◽  
Random Alloy ◽  
Substitutional Alloys ◽  
Effective Cluster

We present a study of the mixing energies and the effective cluster interactions which form the configurational part of the internal energy of Pd-Rh substitutional alloys. We discuss the tendency towards phase-separation and more generally phase stability. The effects of a substitutional ternary addition on the tendencies toward order or phase-separation are also reported. The Korringa-Kohn-Rostoker Coherent-Potential Approximation (KKR-CPA) is used to investigate the electronic structure effects and energetics of the random alloy. Moreover, we use the Generalized Perturbation Method (GPM), using the KKR-CPA random alloy as a reference medium, to investigate the effective interactions which determine phase stability. We briefly comment on other factors which may give important contributions to the total free-energy of the alloy. We also contrast the GPM with the Connolly-Williams approach for calculating phase diagrams from first-principles. Finally, we explore the inadequacies of the frozen-potential and Harris approximations to the energetics of alloying.

Effective Interactions Approach to Phase Stability in Alloys Under Irradiation

1998 ◽  
Vol 538 ◽  
Author(s):  
Raúl A. Enrique ◽  
Pascal Bellon
Keyword(s):  
Phase Diagram ◽  
Phase Stability ◽  
Kinetic Monte Carlo ◽  
Theoretical Frameworks ◽  
Effective Interactions ◽  
Dynamical Phase ◽  
Thermodynamic Potentials ◽  
Simple Kinetic Model ◽  
Kinetic Monte Carlo Simulations ◽  
Competing Dynamics

AbstractPhase stability in alloys under irradiation is studied considering effective thermodynamic potentials. A simple kinetic model of a binary alloy with phase separation is investigated. Time evolution in the alloy results from two competing dynamics: thermal diffusion, and irradiation induced ballistic exchanges. The dynamical (steady state) phase diagram is evaluated exactly performing Kinetic Monte Carlo simulations. The solution is then compared to two theoretical frameworks: the effective quasi-interactions model as proposed by Vaks and Kamishenko, and the effective free energy model as proposed by Martin. New developments of these models are proposed to allow for quantitative comparisons. Both theoretical frameworks yield fairly good approximations to the dynamical phase diagram.

The stability, electronic structure, elastic and metallic properties of manganese nitrides

RSC Advances ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 1620-1627 ◽  
Author(s):  
Ran Yu ◽  
Xiaoyu Chong ◽  
Yehua Jiang ◽  
Rong Zhou ◽  
Wen Yuan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Phase Stability ◽  
First Principles ◽  
First Principles Calculations ◽  
The Stability

The phase stability, electronic structure, and elastic and metallic properties of manganese nitrides (Mn4N, Mn2N0.86, Mn3N2, and MnN) were extensively studied by first principles calculations.

Statics of Phase Transformation in Ni-Al, Ni-Ti And Cu-Zn: a First Principles Study

1991 ◽  
Vol 246 ◽  
Author(s):  
P. E. A. Turchi ◽  
M. Sluiter
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Mean Field ◽  
Potential Approximation ◽  
Chemical Order ◽  
Field Approach ◽  
First Order ◽  
Displacive Transformation ◽  
B2 Phase ◽  
Structure Properties

AbstractWe show that the interplay between electronic structure properties, crystalline effects and local chemical order is quite distinct for Ni-Al, Ni-Ti and Cu-Zn, although they all exhibit a first order displacive transformation upon cooling from a high temperature partially ordered B2 phase. For this purpose, electronic structure and phase stability properties of these three alloys are investigated with a first principles approach. The study is based upon the Generalized Perturbation Method applied to the Korringa-Kohn-Rostoker multiple scattering description of the Coherent Potential Approximation, and temperature effects are taken into account within a generalized mean field approach.

scholarly journals Theoretical Investigation of Phase Stability in Non-Magnetic Fe-V Substitutional Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
Electronic Structure ◽  
Phase Stability ◽  
Tight Binding ◽  
Variation Method ◽  
Equiatomic Composition ◽  
Bcc Lattice ◽  
Slow Kinetics ◽  
Four Levels

The assessed phase diagram of Fe-V exhibits a continuous high temperature bcc solid solution intersected at lower temperatures by a complex sigma phase centered around equiatomic composition [1]. Slow kinetics of the bcc to sigma transformation make it possible to retain the bcc solid solution at low temperature. It has been observed that this metastable solid solution has a tendency to order with a CsCl type structure (B2) below 970 K [1,2]. As a first attempt to describe this behavior from an electronic structure approach, this paper will study the phase stability on the bcc lattice using a realistic tight-binding Hamiltonian. Details of the tight-binding description have been given elsewhere [3]. Main features are as follows: Element and structure specific Slater-Koster parameters are used [4] and lattice parameter effects are incorporated through scaling [5]. Charge transfer is set to zero by rigidly shifting the onsite energies of one constituent. The Coherent Potential Approximation (CPA) is invoked with four levels corresponding to states with s, p, t2g and eg like symmetry. Effects of off-diagonal disorder (ODD) have not been included, instead, an average alloy Hamiltonian was defined using the Slater-Koster parameters of the components weighted by concentration. At equiatomic composition the effect of this approximation has been evaluated by repeating the electronic structure calculation with inclusion of ODD effects (see also [6]). Effective pair interactions, as defined within the Generalized Perturbation Method (GPM) [7], have been computed and have been used to evaluate the ground states of configurational order on the bcc lattice in the Fe-V system. Furthermore, the theoretically derived energetic properties have been used to determine the phase diagram pertaining to the (metastable) bcc lattice with the Cluster Variation Method (CVM) [8] in the tetrahedron approximation

Sign in / Sign up

Export Citation Format

Share Document