Thesis
Defects in metals and simulation of mechanical properties by means of nanoindentation
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/105611
Abstract
Simulations of radiation damage in metals are of real interest when it comes to specifying the effect of radiation in terms of creation of defects such as vacancies, interstitials and dislocations. Molecular Dynamics is a helpful tool in modeling the process of radiation damage in metals on the small scale, since in MD we have a time scale comparable to the real time scale of radiation damage in metals. Zirconium is an important metal for nuclear applications such as for cladding fuel elements; it has a low absorption cross section for neutrons. We have modeled radiation damage in Zr using the PKA method or Displacement cascades that lead to the creation of defects which evolve with time and lead to changes in microstructure and macroscopic properties. Dependence on temperature and on the energy of the primary knocked on atom were studied; vacancies are the main defects generated for PKA energies ranging from 0.5 to 2 kev, and after around 5 ps of the excitation of the PKA the number of defects starts to stabilize. In addition, to characterize the effect of defects on the mechanical properties of metals, we have done molecular dynamics simulations of nanoindentation on Iron with vacancies and dislocations separately inside the metal, the effect of indenter velocity and the numbers of vacancies and dislocations on yield load were also studied; the main results concerning the effect of vacancies and dislocations is that they both lower the yield load of the material during nanoindentation, and a higher concentration of vacancies will cause a higher deviation from the yield point with no vacancies following a weak power law relationship.
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Details
- Title
- Defects in metals and simulation of mechanical properties by means of nanoindentation
- Creators
- Elias K. Njeim
- Contributors
- David F. Bahr (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525377701842
- Language
- English
- Resource Type
- Thesis