Self-diffusion and impurity diffusion of fee metals using the five-frequency model and the Embedded Atom Method

1989 ◽  
Vol 4 (1) ◽  
pp. 102-112 ◽  
Author(s):  
J. B. Adams ◽  
S. M. Foiles ◽  
W. G. Wolfer
Keyword(s):  
Experimental Data ◽  
Transition Metals ◽  
Activation Energies ◽  
Embedded Atom Method ◽  
Vacancy Mechanism ◽  
Frequency Model ◽  
Self Diffusion ◽  
Embedded Atom ◽  
Diffusion Rates ◽  
Jump Frequencies

The activation energies for self-diffusion of transition metals (Au, Ag, Cu, Ni, Pd, Pt) have been calculated with the Embedded Atom Method (EAM); the results agree well with available experimental data for both mono-vacancy and di-vacancy mechanisms. The EAM was also used to calculate activation energies for vacancy migration near dilute impurities. These energies determine the atomic jump frequencies of the classic “five-frequency formula,” which yields the diffusion rates of impurities by a mono-vacancy mechanism. These calculations were found to agree fairly well with experiment and with Neumann and Hirschwald's “Tm” model.

Vacancy diffusion along twist grain boundaries in copper

1991 ◽  
Vol 6 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Miki Nomura ◽  
Sing-Yun Lee ◽  
James B. Adams
Keyword(s):  
Grain Boundaries ◽  
Activation Energies ◽  
Vacancy Formation ◽  
Embedded Atom Method ◽  
Vacancy Diffusion ◽  
High Angle ◽  
Self Diffusion ◽  
Embedded Atom ◽  
And Migration ◽  
Formation Energies

Vacancy diffusion along two different high-angle twist grain boundaries (Σ5 and Σ13) was studied using the Embedded Atom Method (EAM). Vacancy formation energies in all the possible sites were calculated and found to be directly related to the degree of coincidence with the neighboring crystal planes. Optimal migration paths and migration energies were determined and found to be very low. The activation energies for self-diffusion at the boundaries were found to be less than half of the bulk value.

Calculation of Phonon Dispersion for 3d Transition Metals Cr and Fe by Modified Analytic Embedded Atom Method

2011 ◽  
Vol 411 ◽  
pp. 532-536
Author(s):  
You Xie ◽  
Jian Min Zhang
Keyword(s):  
Experimental Data ◽  
Transition Metals ◽  
Phonon Frequency ◽  
Phonon Dispersion ◽  
Phonon Dispersion Curve ◽  
Embedded Atom Method ◽  
Body Centered Cubic ◽  
Phonon Dispersion Curves ◽  
Embedded Atom ◽  
Good Agreement

The modified analytical embedded atom method is applied to calculate the phonon dispersion of body-centered cubic 3d transition metals Cr and Fe along five symmetry directions [q 0 0], [1 q q], [q q q], [q q 0] and [1/2 1/2 q]. Our results of phonon dispersion curves are in good agreement with the available experimental data. For the two transition metals Cr and Fe, along the same direction, a similar phonon dispersion curve is obtained in spite of the phonon frequency decreases for Cr and Fe due to the atom mass increases. There are no experimental results for comparison along the directions [1 q q] and [1/2 1/2 q], further experimental measurement are needed.

APPLICATION OF THE EAM POTENTIALS TO THE STUDY OF DIFFUSION COEFFICIENTS OF LIQUID NOBLE AND TRANSITION METALS

2002 ◽  
Vol 16 (25) ◽  
pp. 3837-3846 ◽  
Author(s):  
A. Z. ZIAUDDIN AHMED ◽  
G. M. BHUIYAN
Keyword(s):  
Experimental Data ◽  
Solid State ◽  
Diffusion Coefficients ◽  
Noble Metals ◽  
Packing Fraction ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Atomic Transport ◽  
Liquid Transition ◽  
Variational Calculations

The embedded atom method (EAM) potentials, originally proposed for solid state calculations, have been applied to investigate the atomic transport property namely the diffusion coefficients of liquid Ni, Cu, Ag and Au. Two different liquid state theories, specifically the linearized Weeks–Chandler–Andersen (LWCA) theory and the Gibbs–Boguliubov variational method (GB) are used to evaluate the packing fraction near melting temperature. Calculated values for the diffusion coefficients are compared with the available experimental data. Results of variational calculations are found to be better in agreement. Results of calculations also allow us to conclude that the concerning EAM potentials are transferable to the study of atomic transport properties of liquid transition and noble metals.

Self-Diffusion in Nano-ZnO

2010 ◽  
Vol 307 ◽  
pp. 27-35
Author(s):  
S.S. Kanmani ◽  
K. Ramachandran
Keyword(s):  
Isotope Effect ◽  
Zno Nanoparticles ◽  
Reaction Coordinate ◽  
Vacancy Mechanism ◽  
Nano Zno ◽  
Self Diffusion ◽  
Jump Frequencies

Self-diffusion, both cationic and anionic, in ZnO nanoparticles was studied here in accord with reaction coordinate theory. The jump frequencies at various temperatures were computed. The isotope effect revealed that self-diffusion occurred mainly via a vacancy mechanism in nano ZnO; a result not previously reported in the literature.

MONTE CARLO SIMULATION OF THE SURFACE SEGREGATION OF Au75Pd25 AT (110) SURFACE USING AN ANALYTIC EMBEDDED ATOM METHOD

2007 ◽  
Vol 14 (03) ◽  
pp. 411-417 ◽  
Author(s):  
YU CHEN ◽  
SHUZHI LIAO
Keyword(s):  
Experimental Data ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Surface Segregation ◽  
Embedded Atom Method ◽  
Depth Profiles ◽  
The Third ◽  
Embedded Atom ◽  
Reconstructed Surface ◽  
Concentration Depth Profiles

The surface concentrations and concentration depth profiles to the (110) surface of an Au 75 Pd 25 alloy is studied by modified analytical embedded atom method (MAEAM) with the Monte Carlo simulations. The results indicate that Au enriched in the two topmost layers, but depleted in the third layer. The Au concentration in the non-reconstructed surface is less than that in the reconstructed surface. Au concentration in third layer of reconstructed surface, which is more agreement with experimental data in present simulations, is about 63% 61% and 55%, at 800K, 600K and 400K respectively. Thus the present simulations are helpful for a better understanding of surface segregation of AuPd alloys.

Self-diffusion along twist grain boundaries in Cu

1992 ◽  
Vol 7 (12) ◽  
pp. 3202-3212 ◽  
Author(s):  
Miki Nomura ◽  
James B. Adams
Keyword(s):  
Experimental Data ◽  
Grain Boundaries ◽  
Reasonable Agreement ◽  
Polycrystalline Material ◽  
Twist Angle ◽  
Vacancy Diffusion ◽  
High Angle ◽  
Self Diffusion ◽  
Diffusion Rates ◽  
Formation Energies

In a previous paper we studied vacancy diffusion in two high-angle twist grain boundaries in Cu, using the EAM. In this paper, we discuss vacancy diffusion along four additional twist grain boundaries, from 8.8–43.6°. Vacancy formation energies in all the possible sites were calculated (0.14–1.42 eV) and found to be directly related to the degree of coincidence with the neighboring crystal planes. The optimal migration paths were found to coincide with the screw dislocations which comprise the boundary. Vacancy migration energies were found to be low (0.02–0.52 eV). The activation energies for self-diffusion at the boundaries were found to be less than half of the bulk value, in general agreement with experiment. Calculated diffusion rates, δD, for medium-high angle twist grain boundaries were in reasonable agreement with experimental data for polycrystalline material. Diffusion rates were found to decrease with increasing twist angle, in contrast with two sets of conflicting experimental data.

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