Superplastic behavior in a powder-metallurgy TiAl alloy with a metastable microstructure

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Superplasticity in a powder-metallurgy TiAl alloy (Ti-47Al-2Cr-2Nb) with a metastable microstructure has been studied. Samples were tested at temperatures ranging from 650 to 1100{degrees}C, and at strain rate ranging from 10{sup -6} to 10{sup -4} s{sup -1}. An elongation value of over 300 obtained at a strain rate of 2 x 10{sup -5} s{sup -1} and at a temperature as lo as 800{degrees}C, which is close to the ductile-to-brittle-transition temperature. This is in contrast to the prior major observations of superplastic behaviors in TiAl in which typical temperatures of 1000{degrees}C have usually been required for superplasticity. It is proposed that ... continued below

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Nieh, T.G.; Hsiung, L.M. & Wadsworth, J. December 1, 1997.

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Superplasticity in a powder-metallurgy TiAl alloy (Ti-47Al-2Cr-2Nb) with a metastable microstructure has been studied. Samples were tested at temperatures ranging from 650 to 1100{degrees}C, and at strain rate ranging from 10{sup -6} to 10{sup -4} s{sup -1}. An elongation value of over 300 obtained at a strain rate of 2 x 10{sup -5} s{sup -1} and at a temperature as lo as 800{degrees}C, which is close to the ductile-to-brittle-transition temperature. This is in contrast to the prior major observations of superplastic behaviors in TiAl in which typical temperatures of 1000{degrees}C have usually been required for superplasticity. It is proposed that the occurrence of superplasticity at 8000{degrees}C in the present alloy is caused by the presence of a B2 phase. During superplastic deformation (grain boundary sliding), the soft P grains accommodate sliding strains to reduce the propensity for cavitation at grain triple junctions and, thus, delays the fracture process. The final microstructure consists of stable, equiaxed y+a{sub 2} grains.

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27 p.; Other: FDE: PDF; PL:

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OSTI as DE98054503

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  • 3. international workshop on ordered intermetallic alloys and composites, Hongzhon (China), 5-10 Apr 1998

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  • Other: DE98054503
  • Report No.: UCRL-JC--129442
  • Report No.: CONF-9804102--
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 328524
  • Archival Resource Key: ark:/67531/metadc689097

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • December 1, 1997

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  • July 25, 2015, 2:20 a.m.

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  • Aug. 4, 2016, 7:07 p.m.

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Nieh, T.G.; Hsiung, L.M. & Wadsworth, J. Superplastic behavior in a powder-metallurgy TiAl alloy with a metastable microstructure, article, December 1, 1997; California. (digital.library.unt.edu/ark:/67531/metadc689097/: accessed December 11, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.