In this thesis, molecular dynamics simulations were performed to characterize the atomic motions governing grain boundary migration in a series of [001] twist boundaries. Particularly, migrations of a =36.87 5, a =22.63 13 and a =40.23 general high angle [001] twist boundaries driven by stored elastic energy in fcc Ni were investigated. Atomic motions during migration were identified as the combination of single atom jump and string-like cooperative atomic motions. The simulation results confirmed that the collective 4-atom shuffle motion was the rate controlling atomic motion during the migration of 5 twist boundary. As grain boundary local symmetry decreasing, string-like cooperative atomic motions became increasingly important. Eventually, both random single atom jump and string-like cooperative motions became dominant during the migration of general non- twist boundary. Furthermore, simulations showed that activation energy for grain boundary migration was well correlated with the average string length occurring within boundary. / Materials Engineering
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/608 |
| Date | 11 1900 |
| Creators | Yan, Xinan |
| Contributors | Zhang, Hao ( Chemcial and Materials Engineering), Tian Tang ( Mechanical Engineering), Adrian Gerlich ( Chemical and Materials Engineering) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 2779972 bytes, application/pdf |
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