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Oxygen induced chemical ordering and ultrafine lamellar structure formation in a Ti-48 at. % Al alloy

Published online by Cambridge University Press:  11 February 2011

Williams Lefebvre ,
Annick Loiseau  and
Alain Menand
Williams Lefebvre
Affiliation:
Groupe de Physique des Materiaux, UMR CNRS 6634, Institut des Matériaux de Rouen, UFR, Sciences et Techniques, Technopôle du Madrillet, 76801 Saint Etienne du Rouvray, FRANCE
Annick Loiseau
Affiliation:
Laboratoire d'Etude des Microstructures, UMR CNRS-ONERA, ONERA, BP 72, 29 av. de la Division Leclerc, 92322 Châtillon, FRANCE
Alain Menand
Affiliation:
Groupe de Physique des Materiaux, UMR CNRS 6634, Institut des Matériaux de Rouen, UFR, Sciences et Techniques, Technopôle du Madrillet, 76801 Saint Etienne du Rouvray, FRANCE
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Abstract

Influence of oxygen on the microstructure development of a Ti-48 at. % Al alloy has been investigated by means of transmission electron microscopy and 1D atom probe. Oxygen is found to significantly increase the temperature of the α → α2 chemical ordering reaction. As a consequence, above a critical oxygen content, the α → α2 transformation is substituted to the α → γm massive transformation when the Ti-48 Al alloy is quenched from the single a-phase field. In such a case, our pervious work has shown that the alloy exhibits a fully (α2 + γ) ultrafine lamellar structure. The present work gives a complete description of the ultrafine lamellar structure formation which, in opposition to the classical lamellar structure formation, involves an intragranular nucleation and growth of the γ phase within the α2 matrix.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 753: Symposium BB – Defect Properties and Related Phenomena in Intermetallic Alloys , 2002 , BB3.6
Copyright
Copyright © Materials Research Society 2003

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References

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