A powder X-ray diffraction study of two aluminum-lithium based alloys
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Authors
Wang, Te-Kang
Subjects
Aluminum-Lithium Alloys
Microstructural development
X-ray Diffraction
Microstructural development
X-ray Diffraction
Advisors
Fox, Alan G.
Date of Issue
1991-03
Date
March 1991
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The microstructures of solution treated, quenched and aged A1-2.5 wt. %Li and A1-2.0 wt.%Li-2.76 wt.%Mg-1.03 wt.%Cu alloys were studied by powder X- ray diffraction. The as-quenched alloys showed extensive X-ray line broadening due to particle size effects and the intensity measurements indicated a significant amount ordering in the as-quenched state. These results were interpreted using a 'spinodal ordering' model which suggests that A1-Li-based alloys order during quenching and then spinodally decompose into regions of order and disorder so that the final microstructure comprises small ordered regions (size 40 nm) in a disordered matrix Studies on the aged A1-2.5 wt.%Li alloy indicated that after initial short-time aging, particle growth follows Ostwald ripening kinetics in agreement with previous work. Studies on the aged quaternary alloy indicated that T1 and S phases grow in this system so that precipitates are not a dominant strengthening mechanism in this alloy.
Type
Thesis
Description
Series/Report No
Department
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
54 p.;28 cm.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
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.