Phase formation and transformation in mechanically alloyed iron-rich Sm-Fe-C is the principal subject of this thesis. Ternary Sm-Fe-C is a complicated system. The strategy was therefore to start with a binary system. A series of mechanically alloyed R$ sb2$Fe$ sb{17}$ powders were investigated for a better understanding of both the Sm-Fe alloy system in general and the Sm$ sb2$Fe$ sb{17}$ compound in particular. The objective was to learn (1) what is the steady-state in the mechanically alloyed R$ sb2$Fe$ sb{17},$ and (2) how the 2-17 structure is formed from the mechanically alloyed precursors. Phase formation and transformation in the mechanically alloyed Sm$ sb2$Fe$ sb{17}$C$ sb{x}$ with various carbon contents was then studied. The objective in this case was to learn (1) how the 2-17 structure with interstitial carbon is formed, (2) what is the maximum C content in the 2-17 structure, the critical content $x sb{c},$ and (3) what phase(s) is (are) formed with $x>x sb{c}.$ / Phase transformation from Sm$ sb2$Fe$ sb{17}$C$ sb{x}$ to Sm$ sb2$Fe$ sb{14}$C was the second subject for study. As required by this study, the grain refinement process was investigated first. The objective was to prepare the nanocrystalline Sm$ sb2$Fe$ sb{17}$C$ sb{x}$ with various grain sizes. Emphasis was on the ball milling of Sm$ sb2$Fe$ sb{17}$/graphite mixture in the hope of forming a nano-scale mixing of Sm$ sb2$Fe$ sb{17}$ and graphite by ball milling. Solid-solid reaction between the Sm$ sb2$Fe$ sb{17}$ and graphite leading to the formation of nanocrystalline Sm$ sb2$Fe$ sb{17}$C$ sb{x}$ was then studied. The phase transformation from Sm$ sb2$Fe$ sb{17}$ was carried out with nanocrystalline Sm$ sb2$Fe$ sb{17}$C$ sb{x}$ samples. Samples prepared by other methods were also studied. The objective was to learn (1) what the transformation product is and (2) what the kinetics of the phase transformation and its grain size dependence are. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.42089 |
| Date | January 1997 |
| Creators | Mao, Ou. |
| Contributors | Strom-Olsen, J. O. (advisor) |
| 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 Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001564949, proquestno: NQ30331, Theses scanned by UMI/ProQuest. |
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