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Simulation of the Effect of Cooling Rate and Chemical Composition on the Atomic Structure of Bulk Metallic Glass Iron-Phosphorus and Nickel-Phosphorus

Hosseinzadeh, Danial | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53202 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Tavakoli, Rouhollah
  7. Abstract:
  8. bulk metallic glass Unlike metal materials that have a crystalline structure, amorphous glass is an amorphous material with an irregular atomic structure that simultaneously has the same physical properties as metals. Due to the absence of crystal defects such as dislocation and grain boundaries, these materials show unique mechanical properties such as high strength and elastic strain, abrasion resistance and proper corrosion. However, their plastic deformation is heterogeneous, concentrated, and accompanied by sudden failure. Unlike metals, these materials do not have a long-range crystalline order, and their atomic structure includes short-range and mid-range order. The short-range order of atomic in these materials has a great impact on the ability to the deformation of these materials before failure. Nickel-phosphorus and iron-phosphorus binary systems are bulk metallic glasses of metal-quasi-metallic glass that, unlike systems containing metal elements, such as copper-zirconium, have been less studied. The purpose of this study is to investigate the short-range order of atomic in two systems of nickel-phosphorus and iron-phosphorus. Since in metal systems the chemical composition and cooling rate have a significant effect on the local atomic structure, in this study the effect of these two parameters is investigated by simulation of molecular dynamics. The glass transition temperature,atomic pair distribution function and Voronoi Analysis were used to investigate. The results of this study showed that the glass transition temperature and localized atomic structure are a function of chemical composition and cooling rate. In addition, unlike metal-metal systems where the local structure of icosahedral is the dominant structure and determines the properties, in these two systems local structures with less order and symmetry are the dominant structures
  9. Keywords:
  10. Molecular Dynamic Simulation ; Bulk Metallic Glass ; Short-Range Order ; Atomic Structure ; Crystalline Structure ; Cooling Rate ; Binary System

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