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X-Ray Scattering from Highly Distorted Lattices Undergoing Phase Separation

Published online by Cambridge University Press:  26 February 2011

Satish I. Rao ,
C.H. Wu  and
C.R. Houska
Satish I. Rao
Affiliation:
Department of Materials Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
C.H. Wu
Affiliation:
Department of Materials Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
C.R. Houska
Affiliation:
Department of Materials Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
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Abstract

Calculations by Krivogtaz [1] dealing with quasiline formation in highly distorted lattices undergoing phase separation have been extended for randomly arranged particles. Qualitative experimental evidence from powder patterns, already in the literature for Cu-Be,Ni-Be,Cu-Ti and Nimonic alloys[2-5], have demonstrated the existence of quasilines. This extended calculation deals with ellipsoids of revolution and allows one to examine different shapes and transformation strains in an anisotropic medium. it is shown that the precipitate transformation strains play a very important role in shaping the Bragg-like profiles. This is most obvious in the intermediate stage which includes Bragg scattering from the lattice, regular static diffuse scattering and the quasiline. For precipitate sizes associated with maximum age hardening, all three normally become scrambled into a broad assymetrically shaped Bragg-like peak. However, a comparison of the theoretical calculations with experimental data from an age hardened Cu-Be alloy shows qualitative agreement, which we believe is due to the non-random nature of precipitation in this system.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 209: Symposium K – Defects in Materials , 1990 , 77
Copyright
Copyright © Materials Research Society 1991

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References

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