Tensile creep deformation and fracture behaviors of the lamellar TiAl alloy of elemental powder metallurgy
- Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Materials Science and Engineering
- Inha Univ., Inchon (Korea, Republic of). Dept. of Metallurgical Engineering
- Pohang Univ. of Science and Technology (Korea, Republic of). Center for Advanced Aerospace Materials
The creep behaviors of the lamellar structured gamma TiAl alloys processed by castings, wrought and P/M using pre-alloyed powder have been reported. However, so far there has been no report on the creep behaviors of the gamma TiAl alloy processed by a hot extrusion of a blended elemental powder mixture. As such, the need to examine the creep behavior of this alloy has prompted the current research. The creep deformation mechanism based on the activation energy and stress exponent is discussed. In addition, the results of microstructural observations with TEM and optical microscope in the condition of beginning of secondary stage and creep fracture are also presented. Under the basis of the measured apparent activation energy and TEM observation for the dislocation structure, the creep deformation of the EPM alloy under the conditions of 150--250 MPa/775--900 C is assumed to be progressed by the dislocation glide in the {gamma} lath but is considered to be controlled by the dislocation climb. However, in condition of 100--150 MPa/800 C, it is suggested that the diffusional creep dominates the creep deformation rather than dislocation motion. Pore formation and coalescence at the lamellar grain boundaries having the normal direction to the tensile stress axis are observed to be the cause of the creep fracture.
- OSTI ID:
- 509163
- Journal Information:
- Scripta Materialia, Vol. 36, Issue 11; Other Information: PBD: 1 Jun 1997
- Country of Publication:
- United States
- Language:
- English
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