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Deformation Mechanisms Responsible for the Creep Resistance of Ti-Al Alloys

Published online by Cambridge University Press:  15 February 2011

M. A. Morris  and
T. Lipe
M. A. Morris
Affiliation:
Institute of Structural Metallurgy, University of Neuchâtel, Av. Bellevaux 51, 2000 Neuchâtel, SWITZERLAND.
T. Lipe
Affiliation:
Institute of Structural Metallurgy, University of Neuchâtel, Av. Bellevaux 51, 2000 Neuchâtel, SWITZERLAND.
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Abstract

Two γ-based Ti-Al alloys with similar grain sizes and, respectively, lamellar and duplex microstructures have been creep tested at 700°C and constant stresses ranging between 280 and 430 MPa. TEM observations have confirmed that the duplex alloy deforms by extensive mechanical twinning whose density increases with applied stress and increasing strain. The new twin interfaces subdivide the γ grains throughout the primary stage of creep. At the onset of the minimum creep rate, the twin interfaces in the duplex alloy behave in the same way as the γ/γ or the α2/γ interfaces in the lamellar alloy. However, single dislocations were also present and it appears that in both alloys the deformation process is controlled by the accumulation and emission of dislocations from the different interfaces.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 460: Symposium Z – High-Temperature Ordered Intermetallic Alloys VII , 1996 , 275
Copyright
Copyright © Materials Research Society 1997

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