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Subboundary Characterization and Creep Deformation in Investment Cast Ti-48Al-2Nb-2Cr

Published online by Cambridge University Press:  22 February 2011

Zhe Jin
Affiliation:
Los Alamos National Laboratory, Materials Science and Technology Division, Los Alamos, NM 87545, U.S.A.
Thomas R. Bieler
Affiliation:
Michigan State University, Department of Materials Science and Mechanics, East Lansing, MI 48824, U.S.A.
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Abstract

Subgrain boundaries (subboundaries) in a creep deformed investment cast Ti-48Al-2Nb-2Cr specimen were characterized. A multi-stress drop test was performed at temperature 765 °C and stresses from 276 MPa to 103 MPa. The stress exponent n = 7. Subboundaries were observed both in equiaxed γ grains and within γ laths in lamellar grains. Dislocations within the subboundaries are characterized to be ordinary 1/2<110] dislocations. Subboundaries are found to occur on many crystallographic planes and no preferred crystallographic planes are found for subboundary formation in the crept TiAl specimen. Misorientations across the subboundaries are less than 1°. Analysis of subboundary formation mode indicates that the creep deformation in TiAl is pure metal type.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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