Virginia Tech
Effects of Carbon on Fracture Mechanisms in Nanocrystalline BCC Iron - Atomistic Simulations
Abstract
dc:description.abstractAtomistic computer simulations were performed using embedded atom method interatomic potentials in α-Fe with impurities and defects. The effects of intergranular carbon on fracture toughness and the mechanisms of fracture were investigated. It was found that as the average grain size changes the dominant energy release mechanism also changes. Because of this the role of the intergranular carbon changes and these mechanisms compete affecting the fracture toughness differently with changing grain size. Grain boundary accommodation mechanisms are seen to be dominant in the fracture of nanocrystalline α-Fe. To supplement this work we investigate grain boundary sliding using the Σ = 5,(310)[001] symmetrical tilt grain boundary. We observe that in this special boundary sliding is governed by grain boundary dislocation activity with Burgers vectors belonging to the DSC lattice. The sliding process was found to occur through the nucleation and glide of partial grain boundary dislocations, with a secondary grain boundary structure playing an important role in the sliding process. Interstitial impurities and vacancies were introduced in the grain boundary to study their role as nucleation sites for the grain boundary dislocations. While vacancies and H interstitials act as preferred nucleation sites, C interstitials do not.
Degree
thesis:*- Name thesis:degree_name
- Ph. D.
- Level thesis:degree_level
- doctoral
- Discipline thesis:degree_discipline
- Materials Science and Engineering
- Department dc:contributor.department
- Materials Science and Engineering
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 2004
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Hyde, Brian
- Chair dc:contributor.committeechair
-
- Farkas, Diana
- Committee members dc:contributor.committeemember
-
- Corcoran, Sean G.
- Batra, Romesh C.
- Reynolds, William T. Jr.
- Kampe, Stephen L.
Subjects
dc:subject × 6Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
Identifiers
dc:identifier.*- Dc Identifier Other
- etd-04262004-153825
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/27315