Theoretical Investigation of Phase Stability in Non-Magnetic Copper-Nickel Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Theoretical Investigation ◽  
Phase Stability ◽  
Nickel Alloys ◽  
Tight Binding ◽  
Enthalpies Of Mixing ◽  
Ni Alloys ◽  
Copper Nickel ◽  
Densities Of States

AbstractThe phase stability of non magnetic Cu-Ni alloys is studied within a tight binding framework. Densities of states, enthalpies of mixing and ultimately the phase diagram are computed and compared to experimental data.

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

THERMODYNAMIC CALCULATION OF PHASE DIAGRAM AND PHASE STABILITY WITH NANO-SIZE PARTICLES

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2645-2650 ◽  
Author(s):  
XING JUN LIU ◽  
CUI PING WANG ◽  
JIAN ZHONG JIANG ◽  
IKUO OHNUMA ◽  
RYOSUKE KAINUMA ◽  
...  
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Phase Stability ◽  
Interfacial Energies ◽  
Pure Metals ◽  
Predicted Values ◽  
Fcc Phase ◽  
Size Of Particles ◽  
Nano Size ◽  
Good Agreement

In the present paper, the surface tensions and interfacial energies for pure metals and alloys for different structures were predicted by combining with the evaluated thermodynamic parameters in the framework of the CALPHAD (Calculation of Phase Diagrams) method. It is shown that the calculated results are in good agreement with the existing experimental data. On the basis of the predicted values of surface tension and interfacial energy, the phase stability and phase diagram with nano-size particles can be calculated by considering the Gibbs-Thomson equation. The calculated results for pure Fe indicate that the fcc phase is more stable with the decreasing of size of particles, which is in agreement with the experimental data reported, and the phase diagram with nano-size particle can be calculated.

THEORETICAL STUDY OF PHASE FORMING, MAGNETIZATION AND LATTICE VIBRATIONS OF Fe23-xTxB6(T = Cr, Mn, Ni, C), Fe23 C6, Fe23B6 AND Fe23CB6

2013 ◽  
Vol 27 (12) ◽  
pp. 1350050 ◽  
Author(s):  
XIAO-XU WANG ◽  
PING QIAN ◽  
ZHI-WEI AN ◽  
YA-PING LI ◽  
ZHEN-FENG ZHANG ◽  
...  
Keyword(s):  
Theoretical Investigation ◽  
Phase Stability ◽  
Theoretical Study ◽  
Magnetic Moments ◽  
Site Preference ◽  
Vibrational Modes ◽  
Lattice Vibrations ◽  
Lattice Constants ◽  
Densities Of States ◽  
Prototype Structure

We present a theoretical investigation on the phase stability, site preference and lattice constants of Fe 23-x T x B 6( T = Cr , Mn , Ni , C ), Fe 23 C 6 and Fe 23 CB 6. The calculated results show that in Fe 23-x T x B 6 the Cr , Mn or Ni atoms prefer 4a sites. Fe 23 CB 6 may form with Cr 23 C 6 prototype structure, and the carbon atoms are positioned at 4a sites. The calculated lattice constants are found to agree with report in literatures. We have calculated the magnetic moments of Fe 23 C 6, Fe 23 B 6 and Fe 23 CB 6 compounds. Furthermore, the total and partial phonon densities of states are evaluated first for these compounds. The analysis of the inverted potentials explains qualitatively the contributions of different atoms to the vibrational modes.

Theoretical Investigation of Phase Stability in Ti-V and Ti-Cr Substitutional Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Phase Diagrams ◽  
Theoretical Investigation ◽  
Phase Stability ◽  
Effective Pair ◽  
Structure Description ◽  
Substitutional Alloys ◽  
Pair Interactions

AbstractThe phase stability of Ti-V and Ti-Cr alloys is examined within the context of an electronic structure description. Energies of mixing, effective pair interactions, and phase diagrams are computed and compared to available experimental data. A metastable distorted B2 type of structure is predicted in near equiatomic Ti-Cr.

Monte Carlo Simulations of Surface Segregation in Cu Ni Alloys

1992 ◽  
Vol 291 ◽  
Author(s):  
A. Pasturel ◽  
V. Drchal ◽  
J. Kudrnovsky ◽  
P. Weinberger
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Surface Segregation ◽  
Tight Binding ◽  
Electronic Structure Calculations ◽  
Orbital Method ◽  
Ni Alloys ◽  
Composition Profiles ◽  
Structure Calculations

ABSTRACTA new method coupling electronic structure calculations with Monte Carlo simulations has been developed to determine surface compositions in Cu-Ni alloys. The calculations are based on an effective Ising model with parameters as defined within the framework of the Generalized Perturbation Method (GPM) and as calculated by means of the tight-binding version of the linear muffin-tin orbital method. The composition profiles are obtained for the fcc(OOl) surface for three bulk compositions, namely Cu75Ni25, Cu50Ni50, and Cu25Ni75 and compared with available experimental data.

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.

scholarly journals Segregation of copper to the surface of copper-nickel alloys

1984 ◽  
Vol 30 (12) ◽  
pp. 7278-7280 ◽  
Author(s):  
P. A. Dowben
Keyword(s):  
Nickel Alloys ◽  
Copper Nickel
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