Influence of Dislocation Density and Distribution on the Aging Behavior of 6061 Al-SiCw Composites
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Authors
Dutta, I.
Bourell, D.L.
Subjects
Advisors
Date of Issue
1990
Date
Publisher
Pergamon Press
Language
Abstract
Precipitation hardening metal-matrix composites (MMCs) are known to age more rapidly than the unreinforced matrix alloys. It has been proposed that the accelerated aging is due to some dislocation defect mechanism which enhances nucleation, growth or both. Theoretical Avrami-type precipitation curves were generated assuming dislocation density dependent nucleation only and dislocation density dependent nucleation and growth. Curves were generated for both uniform dislocation density (to model cold work) and a dislocation density gradient (to model MMCs). These theoretical results were compared to precipitation curves generated by differential scanning calorimetry of unstrained and plastically strained unreinforced 6061 Al and 10 vol.% SiC whisker reinforced 6061 Al MMC. It was found on aging that β′ precipitation in the MMC initiates earlier and is completed later than in the unreinforced alloy with the same amount of plastic work as the composite. The reaction rate order for β′ precipitation was also determined from the calorimetric studies. These experimental results were interpreted in terms of the theoretical calculations. It is concluded that the matrix dislocation density distributions of metal-matrix composites can strongly influence macroscopically observed nucleation and growth rates.
Type
Article
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
DARPA /ARO
Funding
DARPA /ARO No . N00014-84-K-0687
Format
9 p.
Citation
Dutta, I., and D. L. Bourell. "Influence of dislocation density and distribution on the aging behavior of 6061 AlSiCw composites." Acta Metallurgica et Materialia 38.11 (1990): 2041-2049.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.