Title page for ETD etd-05242002-141644


Type of Document Master's Thesis
Author Latapie, Antoine Nicolas
Author's Email Address alatapie@vt.edu
URN etd-05242002-141644
Title Molecular Dynamics Investigation on the Fracture Behavior of Nanocrystalline Fe
Degree Master of Science
Department Materials Science and Engineering
Advisory Committee
Advisor Name Title
Farkas, Diana Committee Chair
Corcoran, Sean Gerald Committee Member
Reynolds, William T. Jr. Committee Member
Keywords
  • molecular statics
  • computer simulation
  • fracture toughness
  • iron
  • Fe
  • fracture
  • alpha iron.
  • nanocrystalline
  • crack propagation
  • molecular dynamics
Date of Defense 2002-05-20
Availability unrestricted
Abstract
Crack propagation studies in nanocrystalline alpha-iron samples with grain sizes ranging from 6 to 12 nm are reported at temperatures ranging from 100K to 600K using atomistic simulations. For all grain sizes, a combination of intragranular and intergranular fracture is observed. Mechanisms such as grain boundary accommodation, grain boundary triple junction, grain nucleation and grain rotation are observed to dictate the plastic deformation energy release. Intergranular fracture is shown to proceed by the coalescence of nanovoids formed at the grain boundaries ahead of the crack. The simulations also show that at an atomistic scale the fracture resistance and plastic deformation energy release mechanisms increase with increasing temperature. Finally a softening of the material occurs with decreasing grain size. The elastic properties are found to decrease and the fracture resistance to increase with decreasing grain size.
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