Al₃Ti, Al₅CuTi₂, and Al₆₆Mn₁₁Ti₂₃, intermetallic matrices reinforced with 30, 40, and 50 volume % TiB, have been produced by XD<sub>™</sub> processing and densified into bulk form by powder metallurgy techniques. The compressive flow behavior of the Al₃Ti and Al₅CuTi₂, composites have been evaluated at temperatures ranging from 1000°C to 1200°C and strain rates of 0.0001 and 0.001 sec⁻¹. The results have been analyzed by a correlation to the resulting microstructure, especially with regards to the intermetallic matrix composition, TiB₂ size, and interparticle spacing. The results of these analyses are applied to a constitutive equation based upon the flow stress equation.
It has been shown that at in this temperature regime, all deformation occurs within the intermetallic matrix. This is substantiated by the lack of TiB₂-dependent behavior with variations in volume percentage of reinforcement. In all cases, the composites are readily deformed at relatively low loads. The average strain-rate sensitivity values were 0.349 for the Al₃Ti-based composites, and 0.247 for the Al₅CuTi₂, variants. The average activation energies were calculated to be 485 kJ/mol and 920 kJ/mol for the Al₃Ti-and Al₅CuTi₂-matrices, respectively. The structure constant was calculated based upon these values. The Zener-Hollomon parameter was used to plot the flow stress along lines of constant temperature and strain rate, and serves as one type of constitutive equation. In addition, the flow stress was evaluated as a function of the strain rate and temperature. These models were found to provide adequate correlation to the measured flow behavior. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/45422 |
| Date | 01 November 2008 |
| Creators | Marte, Judson Sloan |
| Contributors | Materials Science and Engineering |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xii, 84 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 35950272, LD5655.V855_1996.M3758.pdf |
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