Molecular Dynamics Analysis of Temperature Dependence of Liquid Metal Diffusivity

Abstract

The diffusivities of liquid Al, Co, Mg, Ni, and Pb have been calculated with molecular dynamics (MD)-based on semiempirical potentials derived from the second-moment approximation to the tight binding method (TBM-SMA). The liquid structure in terms of pair distribution function described in the present work agrees well with the available experimental data. The diffusion coefficients derived agree well with a limited number of experimental measurements. The calculated diffusivities were also compared with the predictions of available diffusion models, including the activated state model, the moving oscillator model, the density fluctuation model, the free volume model, and the scaling law proposed by Dzugutov. The present work substantiates the density fluctuation model, suggesting that diffusivity D possesses a square proportionality of temperature T 2 . It is concluded that diffusion is materialized in liquid metals through continuous movements of individual atoms over a small distance as a result of local density fluctuations rather than through discrete jumps of atoms over an interatomic distance.

Atomistic simulation of self-diffusion and interfacial diffusion of liquid lead

“…Molecular dynamics simulation results conform to Mathiak et al's experimental results [10] and Yang's simulation results' tendency [9]. Mathiak et al carried out space-lab experiments studies overcoming convection influence caused by the gravity.…”

“…Using molecular dynamics method, Chamati et al [5] researched iron self-diffusion using embedded-atom model (EAM) potential, and Wang and Ni [6][7][8] researched thermal conductivity of germanium and uranium dioxide thin film which showed feasibility of molecular dynamics simulation method to research the material properties. Yang et al [9] simulated self-diffusion coefficient of liquid lead using molecular dynamics simulation method with temperature of 600 K to 2000 K. The work concluded that diffusion is materialized in liquid metals through continuous movements of individual atoms over a small distance as a result of local density fluctuations, rather than through discrete jumping of atoms over an inter atomic distance. Mathiak et al [10] carried out experimental research in the case of overcoming gravity and the results showed a substantial increase in the accuracy of experimental results.…”

Development of an atomic mobility database for liquid phase in multicomponent Al alloys: focusing on binary systems

“…As showni nT able 1, only theoretically predicted selfdiffusion coefficients via MD method exist for liquid Mg. The reported self-diffusion coefficientsf rom Yange ta l. [17], Protopapas et al [14] and Alemany et al [18] agree well with each other, while the values reported by Li et al [19] and Wax et al [20] are larger and smaller than the data from Refs. [14,17,18], respectively.…”

PbTe formation by swift heavy ion beam induced interface mixing of Te/PbO bilayer

“…This value is seven to eight orders of magnitude higher than the diffusivity D $ 10 À10 -10 À11 cm 2 /s [42] of Pb and Te in PbTe in solid state, even at a temperature very close to the melting temperature, which indicates that the diffusion must have taken place in the liquid state. The value of diffusivity of Pb in liquid state is $1.5 Â 10 À4 cm 2 /s [43], which indicates that the estimated inter-diffusion coefficient during transient melt phase is higher by approximately two orders of magnitude than the reported value of diffusivity of Pb in liquid state. Thus, the possibility of diffusion in solid state is ruled out by the large values of the inter-diffusion coefficient, giving the clue that the SHI induced ion beam mixing is due to an inter-diffusion during a transient molten state [21,22,27,44,45].…”