TiC reinforcement particles were incorporated into a Ti-6 %Al-4%V matrix and processed by two powder metallurgy techniques, namely elevated temperature pressureless sintering and hot deformation-assisted sintering (also known as hot pressing). For these composites, processing by sintering alone necessitated high temperatures (>1500°C) for near-complete density consolidation, whilst the conditions for temperature and hold time were reduced (i.e. 1000°C and 1/2 hour) through deformation-assisted sintering. During high temperature processing in the absence of deformation, considerable coarsening of the lamellar matrix microstructure occurred. The interfacial reaction between the reinforcement and matrix was characterized by in situ neutron diffraction sintering studies at temperatures between 1100°C and 1350°C. Initial reaction occurred by carbon diffusion from the TiC particle to the titanium alloy, as evidenced through the increase in the lattice parameter of the matrix phase with holding time at the various sintering temperatures. Beyond the carbon solubility limit of the matrix phase, a stable stoichiometric phase formed as shown by the appearance of distinct peaks in the neutron diffraction patterns. Room temperature lattice parameter measurement gave a value of 4.290 A with a fractional occupancy of carbon of 0.45 +/- 0.04, which corresponds to a stoichiometry of Ti2C. For the various isothermal sintering temperatures, change in the Ti2C volume fraction with hold time was determined and growth of this interfacial phase was reasoned to occur by carbon diffusion from the TiC particles, through the reaction zone and to the Ti-6%Al-4%V alloy. Transformation of the entire TiC particle to Ti2C occurred in the composites sintered at 1500°C. For the composites processed by sintering only, the mechanical properties determined by shear punch testing indicated that the strength and ductility are limited at low temperature sintering because of high por
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36729 |
| Date | January 1999 |
| Creators | Wanjara, Priti. |
| Contributors | Yue, Steve (advisor), Drew, Robin (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 Mining and Metallurgical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001744967, proquestno: NQ64690, Theses scanned by UMI/ProQuest. |
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