Interaction of Tantalum with Reinforcements in Γ TiAl
Lavernia, E. J.
Evidence suggests that tantalum alloying additions can segregate to fiber or reaction zone interfaces in TiAl. The behavior depends on the reinforcing material being studied. Inhomogeneities in tantalum concentration in TiAl owing to segregation are a matter for concern. Other refractory metal additions may also segregate, since they behave similar to tantalum. Samples of Ti-47Al-2Ta with a few reinforcing fibers were hot isostatically pressed. The fibers used were Al2O3-ZrO2 and Si3N4, uncoated and coated with TiC or TiB2. These samples were heated for times up to 500 h at 982 °C in order to simulate potential use temperatures and times. Backscattered scanning electron microscopy, energy dispersive X-ray analysis and electron microprobe analysis were used for the examination. Results include a sixfold increase in tantalum at the interface between a TiB2 coating on a Si3N4 fiber and the matrix, while an uncoated fiber shows an increasing tantalum content in the fiber and reaction zones.
J. W. Newkirk and D. C. Dixon, "Interaction of Tantalum with Reinforcements in Γ TiAl," Materials Science and Engineering: A, Elsevier, May 1992.
The definitive version is available at http://dx.doi.org/10.1016/0921-5093(92)90267-5
Materials Science and Engineering
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