| EPSRC Reference: |
EP/C015649/1 |
| Title: |
Atomistic simulation of gamma/alpha2 interfaces and dislocations relevant to lamellar titanium aluminides |
| Principal Investigator: |
Finnis, Professor MW |
| Other Investigators: |
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| Department: |
Sch of Mathematics and Physics |
| Organisation: |
Queen's University of Belfast |
| Scheme: |
Postdoctoral Mobility PreFEC |
| Starts: |
01 August 2005 |
Ends: |
31 July 2006 |
Value (£): |
62,381
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| No relevance to Underpinning Sectors |
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Summary on Grant Application Form |
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Alloys based on the aluminides of titanium have been investigated extensively in recent years as candidate materials for a variety of high-temperature structural applications. Because of their low density, exceptionally high strength, hardness, creep and corrosion resistance at high temperatures, titanium aluminides are attractive candidates for applications in advanced aerospace engine and airframe components. TiAl alloys for high temperature applications usually have the form of lamellar structures composed of gamma-TiAl and alpha2-Ti3Al phases. They have higher specific strength than Ni based superalloys but their tensile strength is not as high and further improvement of their strength is necessary for them to replace Ni based alloys. The mechanical properties of the titanium aluminides are very sensitive to the microstructure. It is known that refinement of the lamellar size is a promising way of generally improving the yield strength of TiAl alloys, however this is does not work when the lamellae are too thin. The reasons for this are still speculative, but it is suspected that the absence of misfit dislocations when the lamellae are sufficiently thin may reduce the power of the boundaries to block slipping dislocations. The present proposal takes the first steps towards an understanding of the variation of yield strength with lamellar size based on atomistic modelling. We shall make use of the recently derived bond-order potentials for the Ti-Al system since these are physically motivated many-atom potentials that for the first time account well for the properties of both TiAl and Ti3Al. We shall study the structures and energies of gamma-alpha2 interfaces using molecular statics. This will include simulations with and without misfit dislocations, and with stoichiometry variations at the interface. Then we shall study the structures of dislocation cores. In the final part of this preliminary study, if time permits we shall examine the ideal friction stress of the bulk dislocations. An important aspect of this project, which will also be accomplished within the allotted year, is the transfer of skills in atomistic simulation with the latest physically based models to the named PDRA who is coming across from the Engineering Department for this purpose. He will be able to share with the physicists his knowledge of the engineering problems and the techniques of continuum modeling used by the engineers, in which he is expert.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.qub.ac.uk |