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Interfacial Structure and Lattice Mismatch in Lamellar TiAl Alloys

Published online by Cambridge University Press:  22 February 2011

Dennis M. Dimiduk ,
Yongqian Sun  and
Peter M. Hazzledine
Dennis M. Dimiduk
Affiliation:
Wright Laboratory, Materials Directorate, Wright Patterson AFB, OH 45433
Yongqian Sun
Affiliation:
Department of Materials, University of Oxford, Oxford, 0X1 3PH, UK
Peter M. Hazzledine
Affiliation:
UES, Inc., Dayton, OH, 45432
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Abstract

The gamma lamellae in TiAI alloys are rotated relative to each other approximately by multiples of 60˚ so that close packed planes and directions nearly align. However, the deviations caused by the tetragonality of the lattice are important in determining the structure of the interfaces and the internal stresses in the lamellae. These, in turn, strongly affect the mechanical properties of the alloys. In this paper two new electron optical techniques are used to quantify the deviations from pure twist boundaries (1) selected area diffraction from two adjacent twin-related lamellae permits c/a to be measured with high precision, (2) convergent beam diffraction is used to measure tilt components of lamellar boundaries and also rotations of vectors within the lamellar boundaries. The results are discussed in connection with the weak beam observations of interface dislocation structures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 364: Symposium L – High-Temperature Ordered Intermetallic Alloys–VI , 1994 , 599
Copyright
Copyright © Materials Research Society 1995

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