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The Influence of Film-Substrate and Internal Interfaces on the Strength and Ductility of <001> Oriented B2 NiAl-Based Alloys

Published online by Cambridge University Press:  10 February 2011

A. Misra ,
J. T. Kim  and
R. Gibala
A. Misra
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109–2136
J. T. Kim
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109–2136
R. Gibala
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109–2136
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Abstract

The effects of surface films and second phase interfaces on the room temperature ductility of <001> oriented β (B2) NiAl-based alloys were investigated. Significant reduction in flow stress and enhancement in plasticity, as compared to the monolithic β phase, were seen in both film-coated and ductile γ (fcc)/γ' (Ll2) second-phase-containing alloys. The constrained deformation at the film/substrate and interphase interfaces was effective in nucleating mobile a<100> dislocations in the β phase even though the loading axis was approximately parallel to <001>. For the case of film-coated NiAl single crystals deformed in compression, a micro-kinking model is proposed to explain the propagation of a<001> dislocations generated at the film/substrate interface. For multiphase β/γ+γ' alloys where 10–12% tensile ductility was observed, the role of crystallographic orientation relationships in promoting slip transfer is highlighted. In these multiphase alloys, the intrinsic tensile ductility of β phase by {011}<100> slip when deformed approximately along the <001>β orientation is explained using lattice rotation concepts.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 458: Symposium W – Interfacial Engineering for Optimized Properties , 1996 , 203
Copyright
Copyright © Materials Research Society 1997

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References

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