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Molecular Dynamics Simulation of Thin Film Growth and Nucleation Processes of Rapid Solidification of Aluminum in Nano-Scale

Solhjoo, Soheil | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41277 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Simchi, Abdolreza; Ashuri, Hossein
  7. Abstract:
  8. In this project, the melting, solidification and remelting processes and also, the epitaxial growth of thin molten layer on the solidified crystalline substrate is studied using molecular dynamics simulation for the aluminum as an instance for the fcc metals. Sutton-Chen potential is used for energy calculations; the modified version of verlet algorithm is used for determination of position and velocity of atoms; and the berendsen algorithms are used as thermostat and barostat. The effects of pressure and temperature changing rate on the melting and crystallization temperatures and the crystal structure are investigated. The crystal structure of the system is examined using radial distribution function. The melting and solidification temperatures studied using heat capacity values and mean square displacement plots. The results showed that increasing the heating rate and pressure increase the melting point. The solidification products may have a crystal or amorphous structure depend on the cooling rate and the pressure; higher cooling rates under lower pressures decrease the ability of the system to solidify with a crystal structure. The results show that the remelting temperature depends on the crystal structure besides the temperature changing rate and pressure. In the epitaxial growth simulations, the effects of thickness of the molten nanolayer, temperature of the susbtrate and the direction of growth on the growth velocity are examined. Increasing the thickness of the molten nanolayer, the temperature of the substrate and the density of planes in the direction of growth decreases the velocity of epitaxial growth
  9. Keywords:
  10. Molecular Dynamic Simulation ; Melting ; Solidification ; Electroslag Refining ; Pressure ; Temperature Changing Rate ; Epitaxial Growth

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