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Some Characteristics of Al12Mo in Aluminum Annealed After Implantation with Molybdenum

Published online by Cambridge University Press:  26 February 2011

L. D. Stephenson
Affiliation:
U. S. Army Construction Engineering Research Laboratory, 2902 Newmark Drive, Champaign, IL 61820
J. Bentley
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P. 0. Box X, Oak Ridge National Laboratory, Oak Ridge, TN 37831
R. B. Benson Jr
Affiliation:
North Carolina State University, Department of Materials Engineering, 229 Riddick Hall, Raleigh, NC 27695
G. K. Hubler
Affiliation:
Condensed Matter and Radiation Sciences Division, Naval Research Laboratory, 4555 Overlook Drive S. W., Washington, DC 20375
P. A. Parrish
Affiliation:
Defense Advanced Research Projects Agency, 1400 Wilson Boulevard, Arlington, VA 22209
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Abstract

The characteristics of A112Mo formed in aluminum annealed after implantation with selected maximum molybdenum concentrations were examined by analytical electron microscopy techniques. The A112MO was isolated as the only precipitate in the microstructure for maximum as-implanted molybdenum concentrations up to 11 atomic percent. The morphology of the A112MO can be selected by choosing the maximum as-implanted molybdenum level over the same concentration range. A predominantly lamellar A112MO precipitate structure formed when aluminum was annealed at 550°C after implantation with maximum molybdenum concentrations in the range of 3.3 - 4.4 at.%. The orientation of the body centered cubic (bcc) A112Mo precipitate with respect to the face centered cubic (fcc) matrix can be expressed as (123)p || (002)m and [301]p || [310]m. An explanation for the experimentally observed orientation relationship was developed based on the characteristic relationships between the bcc A112MO precipitate and the fcc matrix. A continuous film of A112MO formed in the surface modified region when aluminum was annealed after implantation with maximum molybdenum concentrations in the approximate range of 8-11 at.%. The microstructure of the A112Mo film was found to depend on the annealing temperature. A granular film formed after annealing at 550°C whereas a mottled film formed after annealing at 400°C. Sequential annealing experiments revealed that the mottled film transforms to a granular film which indicates the mottled film is metastable.

Type
Research Article
Copyright
Copyright © Materials Research Society 1985

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References

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