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Title: Theoretical investigation of phase stability in non-magnetic Fe-V substitutional alloys

Abstract

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. 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. 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. Main features are as follows: Element and structure specific Slater-Koster parameters are used and lattice parameter effects are incorporated through scaling. 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, t{sub 2g} and e{sub g} 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 structuremore » calculation with inclusion of ODD effects. Effective pair interactions, as defined within the Generalized Perturbation Method (GPM), 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) in the tetrahedron approximation. 11 refs., 4 figs., 1 tab.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (USA)
Sponsoring Org.:
DOE/DP
OSTI Identifier:
6292378
Report Number(s):
UCRL-JC-104593; CONF-901105-84
ON: DE91006711
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Fall meeting of the Materials Research Society, Boston, MA (USA), 24 Nov - 1 Dec 1990
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 74 ATOMIC AND MOLECULAR PHYSICS; IRON ALLOYS; PHASE STABILITY; VANADIUM ALLOYS; BCC LATTICES; CONFIGURATION INTERACTION; ELECTRONIC STRUCTURE; ALLOYS; CRYSTAL LATTICES; CRYSTAL STRUCTURE; CUBIC LATTICES; STABILITY; 360102* - Metals & Alloys- Structure & Phase Studies; 640302 - Atomic, Molecular & Chemical Physics- Atomic & Molecular Properties & Theory

Citation Formats

Sluiter, M, and Turchi, P E.A. Theoretical investigation of phase stability in non-magnetic Fe-V substitutional alloys. United States: N. p., 1990. Web.
Sluiter, M, & Turchi, P E.A. Theoretical investigation of phase stability in non-magnetic Fe-V substitutional alloys. United States.
Sluiter, M, and Turchi, P E.A. 1990. "Theoretical investigation of phase stability in non-magnetic Fe-V substitutional alloys". United States. https://www.osti.gov/servlets/purl/6292378.
@article{osti_6292378,
title = {Theoretical investigation of phase stability in non-magnetic Fe-V substitutional alloys},
author = {Sluiter, M and Turchi, P E.A.},
abstractNote = {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. 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. 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. Main features are as follows: Element and structure specific Slater-Koster parameters are used and lattice parameter effects are incorporated through scaling. 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, t{sub 2g} and e{sub g} 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. Effective pair interactions, as defined within the Generalized Perturbation Method (GPM), 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) in the tetrahedron approximation. 11 refs., 4 figs., 1 tab.},
doi = {},
url = {https://www.osti.gov/biblio/6292378}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 18 00:00:00 EST 1990},
month = {Tue Dec 18 00:00:00 EST 1990}
}

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