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The Influence of Solid Solutions on Flow Behavior in -γ-TiAl

Published online by Cambridge University Press:  10 February 2011

C. Woodward
Affiliation:
Materials Research Division, UES Inc, Dayton, OH 45432
S. A. Kajihara
Affiliation:
Materials Research Division, UES Inc, Dayton, OH 45432
S. I. Rao
Affiliation:
Materials Research Division, UES Inc, Dayton, OH 45432
D. M. Dimiduk
Affiliation:
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB OH 45433-6533
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Abstract

Modifications of alloy chemistry are often used to tailor the intrinsic flow behavior of structural materials. Models of solution strengthening, high temperature yield stress and creep must relate the effects of chemistry to the mechanisms that influence these material properties. In ordered alloys, additional information regarding the crystallographic site occupancy of ternary elements is required. In this study relaxed structures and energies for intrinsic and substitutional point defects are calculated using a first principles plane-wave-pseudopotential method. Calculated defect energies are used to predict the density and site preferences of solid-solutions (Si, Cr, Nb, Mo, Ta and W) in ³TiAl. Size and modulus misfit parameters are calculated and the interaction of these defects with a dissociated ordinary screw dislocation evaluated within anisotropic elasticity theory. The derived interaction strength is then related to solid-solution strengthening for these defect centers. Predicted solid-solution effects are in good agreement with experimental observations for the binary alloy.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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