Effect of tungsten, molybdenum and silicon additions on the creep resistance of a gamma titanium aluminide alloy

Conference · Sun Dec 31 00:00:00 EST 1995

OSTI ID:225148

Seo, D Y; Bieler, T R ^[1]; An, S U ^[2]; Larsen, D E ^[3]; Bhowal, P; Merrick, H ^[4]

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1. Michigan State Univ., East Lansing, MI (United States). Dept. of Materials Science and Mechanics
2. KIST, Seoul (Korea, Republic of). Advanced Analysis Center
3. Howmet Corp., Whitehall, MI (United States)
4. Textron Lycoming, Stratford, CT (United States)

Alloy development programs involving gamma titanium aluminide alloys have mainly focused on increasing room temperature ductility, but this has been achieved at the expense of creep properties. Since recent engine tests have been successful with materials having a ductility of about 1.5%, this study focuses on the effects of W, Mo and Si additions. The creep rate is reduced by a factor of 30 at 760 C (1,400 F). Microstructure studies described below show that 0.2--2 {micro}m precipitates form during primary creep deformation and these precipitates interfere with dislocation mobility. These precipitates contain higher concentrations of W and Mo than found in the matrix, but they have a crystal structure that correlates with the Ti{sub 5}Si{sub 3} crystal structure. In addition, a substantial fraction of initial creep strain is accommodated by formation of mechanical twins parallel to lamellar planes that refine the lamellar spacing, and these also initiate mechanical twinning in the equiaxed grains.

• OSTI ID: 225148
• Report Number(s): CONF-950201-; ISBN 0-87339-304-X; TRN: IM9621%%78
• Resource Relation: Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society (TMS), Las Vegas, NV (United States), 12-16 Feb 1995; Other Information: PBD: 1995; Related Information: Is Part Of Gamma titanium aluminides; Kim, Y.W. [ed.] [UES, Inc., Dayton, OH (United States). Materials and Processes Div.]; Wagner, R. [ed.] [GKSS Research Center, Geesthacht (Germany). Inst. for Materials Research]; Yamaguchi, Masaharu [ed.] [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering]; PB: 1023 p.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
33 ADVANCED PROPULSION SYSTEMS
TITANIUM ALLOYS
MICROSTRUCTURE
CREEP
ALUMINIUM ALLOYS
NIOBIUM ALLOYS
MANGANESE ALLOYS
INTERNAL COMBUSTION ENGINES
MATERIALS
TUNGSTEN ADDITIONS
MOLYBDENUM ADDITIONS
SILICON ADDITIONS
INTERMETALLIC COMPOUNDS
SAMPLE PREPARATION
CASTING
HOT PRESSING
HEAT TREATMENTS
PRECIPITATION
DISLOCATIONS
STRAINS
LAMELLAE
TWINNING
TRANSMISSION ELECTRON MICROSCOPY
ELECTRON DIFFRACTION