High-temperature deformation behavior of a gamma TiAl alloy—Microstructural evolution and mechanisms

  • Jeoung Han Kim
  • Young Won Chang
  • Chong Soo Lee
  • Tae Kwon Ha
Article

Abstract

The present investigation was carried out in the context of the internal-variable theory of inelastic deformation and the dynamic-materials model (DMM), to shed light on the high-temperature deformation mechanisms in TiAl. A series of load-relaxation tests and tensile tests were conducted on a fine-grained duplex gamma TiAl alloy at temperatures ranging from 800 °C to 1050 °C. Results of the load-relaxation tests, in which the deformation took place at an infinitesimal level (ε ≅ 0.05), showed that the deformation behavior of the alloy was well described by the sum of dislocation-glide and dislocation-climb processes. To investigate the deformation behavior of the fine-grained duplex gamma TiAl alloy at a finite strain level, processing maps were constructed on the basis of a DMM. For this purpose, compression tests were carried out at temperatures ranging from 800 °C to 1250 °C using strain rates ranging from 10 to 10−4/s. Two domains were identified and characterized in the processing maps obtained at finite strain levels (0.2 and 0.6). One domain was found in the region of 980 °C and 10−3/s with a peak efficiency (maximum efficiency of power dissipation) of 48 pct and was identified as a domain of dynamic recrystallization (DRx) from microstructural observations. Another domain with a peak efficiency of 64 pct was located in the region of 1250 °C and 10−4/s and was considered to be a domain of superplasticity.

Keywords

Material Transaction Power Dissipation Inelastic Deformation Intergranular Crack TiAl Alloy 

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Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2003

Authors and Affiliations

  • Jeoung Han Kim
    • 1
  • Young Won Chang
    • 1
  • Chong Soo Lee
    • 1
  • Tae Kwon Ha
    • 2
  1. 1.the Center for Advanced Aerospace Materials and the Department of Materials Science and EngineeringPohang University of Science and TechnologyPohangKorea
  2. 2.the Research Institute of Industrial Science and TechnologyPohangKorea

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