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Title: Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

Abstract

X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. Themore » application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and measures its thickness. • The ∼ 1 micrometer thickness of the eutectic lamella correlates to the cooling rate.« less

Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
22403534
Resource Type:
Journal Article
Journal Name:
Materials Characterization
Additional Journal Information:
Journal Volume: 95; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1044-5803
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ALUMINIUM; ALUMINIUM BASE ALLOYS; COMPUTERIZED TOMOGRAPHY; COPPER; COPPER ALLOYS; DENDRITES; EUTECTICS; IMAGES; MICROSTRUCTURE; NANOSTRUCTURES; RESOLUTION; SOLIDIFICATION; X RADIATION; X-RAY RADIOGRAPHY

Citation Formats

Patterson, B.M., E-mail: bpatterson@lanl.gov, Henderson, K.C., Gibbs, P.J., Imhoff, S.D., and Clarke, A.J. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures. United States: N. p., 2014. Web. doi:10.1016/J.MATCHAR.2014.06.004.
Patterson, B.M., E-mail: bpatterson@lanl.gov, Henderson, K.C., Gibbs, P.J., Imhoff, S.D., & Clarke, A.J. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures. United States. doi:10.1016/J.MATCHAR.2014.06.004.
Patterson, B.M., E-mail: bpatterson@lanl.gov, Henderson, K.C., Gibbs, P.J., Imhoff, S.D., and Clarke, A.J. Mon . "Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures". United States. doi:10.1016/J.MATCHAR.2014.06.004.
@article{osti_22403534,
title = {Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures},
author = {Patterson, B.M., E-mail: bpatterson@lanl.gov and Henderson, K.C. and Gibbs, P.J. and Imhoff, S.D. and Clarke, A.J.},
abstractNote = {X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and measures its thickness. • The ∼ 1 micrometer thickness of the eutectic lamella correlates to the cooling rate.},
doi = {10.1016/J.MATCHAR.2014.06.004},
journal = {Materials Characterization},
issn = {1044-5803},
number = ,
volume = 95,
place = {United States},
year = {2014},
month = {9}
}