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Dynamics of Laves Phase Intersections in a Concentration Gradient

Published online by Cambridge University Press:  21 February 2011

C. W. Allen
C. W. Allen*
Affiliation:
Department of Metallurgical Engineering and Materials Science, University of Notre Dame, Notre Dame, IN 46556
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Abstract

In the approximate interval 850–1150C, the Laves phase TiCr2 exhibits several composition dependent structures, ranging from two layer hexagonal (2H), denoted C14, to face-centered cubic, denoted C15, for Ti-deficient and Ti-excess material, respectively. Intermediate stacking variants such a dihexagonal (4H), denoted C36, may also exist. The Laves phase band in a Ti-Cr microdiffusion couple is examined in cross-section TEM at ambient temperature, after a 1000 C anneal. The band consists of very faulty hexagonal material, at least in part reflecting rapid shear transformation on cooling; in addition the cubic phase is present, in some instances within the same grain as the hexagonal phase. The cubic/hexagonal interfaces are approximately parallel rather than perpendicular to the bulk diffusion direction. Due to a difference in Ti and Cr fluxes, there is a gradual transformation of cubic to hexagonal by a shear mechanism. A model for the mobility of the hexagonal/cubic interface in a concentration gradient is proposed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 39: Symposium G – High-Temperature Ordered Intermetallic Alloys I , 1984 , 141
Copyright
Copyright © Materials Research Society 1985

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References

REFERENCES

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