Rate and environmental effects on fracture of a two-phase TiAl-alloy |
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Authors: | K S Chan Y -W Kim |
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Affiliation: | (1) Southwest Research Institute, 78228-0510 San Antonio, TX;(2) Material Research Division, Universal Energy Systems, 45432-1894 Dayton, OH |
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Abstract: | The influence of strain rate and environment on the fracture behavior of a two-phase TiAl-alloy, Ti-47Al-2.6Nb-2(Cr + V),
heat-treated to a nearly fully lamellar microstructure has been studied by performing conventional tensile, compression, and
fracture toughness tests in air, argon, and vacuum at 25 °C and 800 °C. Both tensile and compression tests were conducted
at strain rates of 1 × 10−3 and 1 × 10−5 s−1, and fracture toughness tests were performed under displacement rates of 0.25 to 2.5 mm/min. In addition,in situ fracture toughness tests were conducted at slow rates both in vacuum and in air. The results indicated that both strain rate
and environment affected the tensile stress-strain behavior and ductility and the fracture resistance of the TiAl-alloy at
800 °C. In contrast, neither the tensile ductility nor the fracture toughness was significantly affected by the environment
at ambient temperature. For compression in air, the stress-strain behavior was insensitive to both strain rate and test temperature
within the conditions tested. Studies of fracture surfaces revealed that low tensile ductility in this alloy at ambient temperature
is associated with the tendency to delaminate alongγ/γ andγ/α
2 interfaces.
formerly with Metcut-Materials Research Group, Wright-Patterson AFB, Dayton, OH 45433-0511 |
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