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Rapid Synthesis of Nanostructural Intermetallics and their Bulk Properties

Published online by Cambridge University Press:  10 February 2011

S. M. Pickard
Affiliation:
Materials Science and Engineering Department, The University of Michigan, Ann Arbor MI 48109
A. K. Ghosh
Affiliation:
Materials Science and Engineering Department, The University of Michigan, Ann Arbor MI 48109
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Abstract

A rapid physical vapor deposition process (PVD) utilizing a high speed rotating substrate and small substrate-to-source spacing has been used to produce bulk sheet of Ti-Al alloys in the compositional range Ti-12% Al to Ti-75% Al1 at a rate of 1–3 μm/minute. Microstructural architectures produced by the method comprise of either fully homogenous phase mixtures of nano-grains, or nanolaminated material, depending on the substrate rotational rate, with lower rotational rate producing a layered microstructure. Defect populations within the as-deposited material are characterized by TEM and SEM, and hot pressing consolidation of the as-deposited material, which retains a grain size < 1000 nm, has been investigated. While indentation hardness of α2+γ(2 phase) alloys exceeded 7 GPa, brittle failure occurred in the elastic regime at nominally lower tensile stress than that for conventionally produced alloys containing Nb and Cr as solute elements. α2+γ alloys can exhibit tensile elongations of more than 100% at 850°C with retention of fine grain size. Elevated temperature failure occurs by the formation of voids in regions of compositional variability in the composite where single phase α2-Ti3Al structure was present.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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