Papers by Keyword: Surface Diffusion

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Authors: Howatchinou Tossoukpe, François Valdivieso, Julien Bruchon, Sylvain Drapier
Abstract: This paper presents a level set framework for the modelling of doping effect during surfacediffusion phenomena in a granular packing. The molecular flux of the doped compound is related tothe chemical potentials of all the diffusion species. The evolution of the grain compact is simulatedin three dimensions, based on the resulting kinetic law relating the surface diffusion velocity to thethermodynamic driving force. An anisotropic adaptive mesh, based on the level set function propertiesis used to refine the mesh in the surroundings of the grain surface. The simulations have been perfomedby using parallel computing strategy.
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Authors: Jun Jie Shen, Kenichi Ikeda, Satoshi Hata, Hideharu Nakashima
Abstract: The creep deformation in pure aluminum was investigated using helicoid spring samples at room temperature, 298 K, and σ < 1.19 MPa. It was found that the stress exponent is n = 0, which means the creep behavior in this region is independent on applied stress but some physical properties of materials. The creep behavior was suggested to be controlled by surface diffusion based on the strongly effect of surface area on creep behavior only in this creep region (n = 0). The threshold creep rate, , called intrinsic deformation limit, decided by surface diffusion was suggested. This discovery provided a new perspective to understand the extremely slow deformation in the nature.
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Authors: Evgenii V. Pustovalov, Alexander F. Fedorets, Vladimir V. Tkachev, Vladimir S. Plotnikov
Abstract: The structure of electrolytically deposited nanocrystalline alloys of the CoP-CoNiP systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures from 150°C to 300°C. Structural and compositional inhomogeneities were found in the CoP-CoNiP alloys, while the local changes in composition were found to reach 15 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface. It was determined that the local diffusion coefficient ranged from 1.2 to 2.4 10−18 m2/s, which could be explained by the surface diffusion prevalence. The data gathered in these investigations can be further used to predict the thermal stability of CoP-CoNiP alloys.
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Authors: Duo Zhang, Lin Zhang
Abstract: The geometry structure and adsorption energy of Cu cluster adsorbed on Au (010) surface were affected by both the height of adsorption site and temperature. The height of adsorption site has major impact on the geometry structure and adsorption energy of the cluster when the temperature is low; while it has minor impact on the geometry structure and adsorption energy of the cluster at higher temperature. The adsorption energy is relevant to the atom number of the first layer on the surface vector of the clusters.The structural of Cu clusters on Au surface and its diffusion properties were studied in this paper by molecular dynamics simulation method and computer graphics techniques. The interaction potential between atoms is adopted by EAM form proposed by Johnson, simulation adopted by canonical ensemble of molecular dynamics method, and computer simulation was adopted to simulate the atomic structure of copper clusters of different amounts of atomic layers at different temperature during heating process. Moreover the analysis of the distribution function and the mean square displacement curve were performed by two representativ kinds of copper clusters Cu55, Cu201.
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Authors: Simon P.A. Gill, Paul E. Spencer
Abstract: A kinetic Monte Carlo (KMC) model for surface diffusion on a 2D lattice is proposed. An equivalent continuum cellular automaton (CA) model is derived from this. These models are shown to produce similar results at high temperatures. A hybrid KMC-CA model is derived which consistently allows material to transfer between a deterministic CA model and a stochastic KMC model concurrently embedded within it. The quality of the model is demonstrated by simulating the flattening of a sinusoidal surface profile and the evolution of an elliptical body into a circular one.
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Authors: Alexander Tarasenko, Lubomir Jastrabik, F. Nieto, C. Uebing
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