A first report on the creep deformation and damage behavior of a fine grained fully transformed lamellar gamma TiAl alloy
- Metals Technology, Inc., Northridge, CA (United States)
- AF Material Command/USAF, Tokyo (Japan). AFOSR/Asian Office of Aerospace Research
Gamma TiAl is a strong candidate material for the replacement of many Ni-based superalloys in advanced gas turbine jet engines. Although gamma TiAl is targeted specifically as a high temperature material, it must also be able to demonstrate reasonable toughness such as measured by impact resistance and must demonstrate reasonable crack growth resistance under cyclic deformation conditions. Of course the main attractive feature of gamma TiAl is that its high temperature creep deformation resistance and damage tolerance is high. There are three basic microstructures which may be produced in gamma TiAl depending on composition and heat treatment. These microstructures and their corresponding properties have recently been discussed extensively by Huang and Hall and Huang. Briefly, the three microstructures are a duplex microstructure consisting of a mixture of lamellar grains containing alternate laths of alpha-2 (Ti{sub 3}Al) and gamma (TiAl) and equiaxed primary gamma grains, a fully transformed structure consisting only of coarse (d > 500{micro}m) lamellar grains and a single phase gamma structure consisting only of equiaxed gamma TiAl grains. In a recent article on microstructure-property tradeoffs in wrought TiAl, Huang has suggested that an optimum balance of each of the properties cited above may be obtained by producing a fully transformed lamellar structure but with a finer grain size than those produced by heat treatment of the two phase TiAl alloys above the alpha transus. Preliminary investigations of the uniaxial tensile properties and the fracture toughness of a fine grained fully transformed TiAl alloy Ti-48Al-2Mn-2Nb have demonstrated very promising results. However, the high temperature creep deformation and damage behavior of this material has yet to be evaluated. The intent of this paper is to present a first report on the high temperature creep deformation and damage behavior of the fine grained fully transformed Ti-48Al-2Mn-2Nb alloy.
- OSTI ID:
- 231091
- Journal Information:
- Scripta Metallurgica et Materialia, Vol. 30, Issue 2; Other Information: PBD: 15 Jan 1994
- Country of Publication:
- United States
- Language:
- English
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