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Analysis of Cavitation in a Near-γ Titanium Aluminide During High-Temperature/Superplastic Deformation

Published online by Cambridge University Press:  10 February 2011

Carl M. Lombard
Affiliation:
Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/MLLM, Wright-Patterson Air Force Base, OH, 45433
Amit K. Ghosh
Affiliation:
Univ. of Michigan, Dept. of Materials Science & Engineering, Ann Arbor, MI, 48109
S. Lee Semiatin
Affiliation:
Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/MLLM, Wright-Patterson Air Force Base, OH, 45433
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Abstract

The superplastic flow behavior of a near-γ titanium aluminide (Ti-45.5Al-2Cr-2Nb) is determined under uniaxial tension in as-rolled or rolled-and-heat treated conditions (1177°C/4 hr or 1238°C/2 hr). Cavitation characteristics, including cavity growth rates, are established via isothermal, constant strain rate tests conducted at 10−4 to 10−2 s−1 and temperatures between 900°C and 1200°C. Differences in cavitation as a function of initial structure, strain, strain rate and temperature are noted. Cavity growth is found to be largely plasticity controlled. Experimental growth rates are compared with equations that predict rates as a function of strain rate sensitivity. Although the equations assume no coalescence and no nucleation of new cavities, which are experimentally observed, they are useful in predicting actual growth rates.

Type
Research Article
Copyright
Copyright © Materials Research Society 2000

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