The misorientations between FCC and BCC crystals are characterized according to the common lattice correspondence relationships in terms of their parallelism conditions. Individual variants of the six models, namely the Bain, Kurdjumov-Sachs, Nishiyama-Wassermann, Pitsch, Greninger-Troiano and inverse Greninger-Troiano relations, are identified and represented in both pole figure form and in Rodrigues-Frank space with respect to various coordinate frames. In this way, the relations between the variants of these models are clarified. / The orientations of the kamacite (BCC) lamellae transformed from a single prior-taenite (FCC) grain in the Gibeon meteorite were measured by analyzing the electron backscatter diffraction patterns. The local misorientations between individual FCC and BCC crystals along their common interfaces were computed and are compared with the common lattice correspondence relationships. The orientation relations between the alpha and gamma phases in the plessite regions are also characterized. The Neumann bands (mechanical twins) and their orientation variations within individual kamacite lamellae were studied and analyzed. / A Nb-bearing TRIP steel was control rolled and a certain amount of austenite was retained through appropriate heat treatment. EBSD measurements were conducted on specimens deformed to various reductions and the textures (ODF's) of both the gamma and alpha phases were obtained from the measured data points. The orientations of the bainite formed within individual prior-austenite grains are compared to those expected from the common correspondence relationships and the average orientation of the prior-austenite grain. The crystallography of the bainite laths within a single packet is also characterized. / The orientations of the bainite formed from individual prior-austenite grains are analyzed with respect to their parent orientations. The occurrence of variant selection at the grain scale was examined using a dislocation-based model. The model considers the role of the slip systems that were active during prior deformation, as well as those of in-plane reaction, cross-slip and the partial dislocations that are linked to specific variants. In this model, the K-S and N-W correspondence relations are united through the dissociation of perfect dislocations. The variants in more than 70% of the grains examined are reasonably well predicted by this model.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85916 |
| Date | January 2005 |
| Creators | He, Youliang, |
| Publisher | McGill University |
| 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 | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Mining, Metals and Materials Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002271892, proquestno: AAINR21653, Theses scanned by UMI/ProQuest. |
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