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Microstructure and Mechanical Properties of Ll2-Structure Alloys Based on Al3Zr

Published online by Cambridge University Press:  26 February 2011

J. H. Schneibel  and
W. D. Porter
J. H. Schneibel
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, TN 37831
W. D. Porter
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, TN 37831
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Abstract

The tetragonal compound Al3Zr can be transformed into the cubic Ll2 structure by additions of Cr, Fe, Ni or Cu. This result is interpreted in terms of Pettifor's structure map. The transformation is accompanied by substantial softening. The significant porosity of cast buttons which develops during the homogenization required to produce the Ll2 structure is attributed to the Kirkendall effect. Al-5.5Fe-25Zr (at. %) specimens with the Ll2 structure can be deformed at room temperature in compression, and their yield stress has been determined as a function of temperature. Al-Fe-Zr is nevertheless a brittle material. This is illustrated for Al-Fe-V-Zr Ll2-structure compound, the fracture toughness of which is only slightly higher than that of sintered SiC. Evidence is presented to suggest that Ll2 formation is accompanied by an increase in toughness. Significant improvements in the mechanical properties of Al3Zr-type alloys may possibly be achieved by improved processing.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 133: Symposium H – High-Temperature Ordered Intermetallic Alloys III , 1988 , 335
Copyright
Copyright © Materials Research Society 1989

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References

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