Papers by Author: Jeffrey Wadsworth

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Authors: Jeffrey Wadsworth, M. Cobian
Abstract: As we enter the 21st century, we confront three global challenges that can be resolved only with forefront science and technology: growing demands for energy, the adverse effects of climate change, and emerging threats to national and global security. Materials science is critical to the fields of research, development, and application that are essential to meeting these challenges. The increasing globalization of scientific research and technology development presents its own challenges at the national level, but also opens the way to new opportunities for fruitful collaboration in materials science.
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Authors: Oleg D. Sherby, Jeffrey Wadsworth
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Authors: Oleg D. Sherby, Manuel Carsí, Woo Jin Kim, Donald R. Lesueur, Oscar A. Ruano, C.K. Syn, Eric M. Taleff, Jeffrey Wadsworth
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Authors: Oleg D. Sherby, T.G. Nieh, Jeffrey Wadsworth
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Authors: Oleg D. Sherby, T.G. Nieh, Jeffrey Wadsworth
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Authors: T.G. Nieh, Jeffrey Wadsworth
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Authors: Oleg D. Sherby, Jeffrey Wadsworth, D.R. Lesuer, C.K. Syn
Abstract: The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usually illustrated to show a linear change in the c and a axes with an increase in carbon content from 0 to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linear relationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure is the stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change in the c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increases with further increase in carbon content. An identical observation is noted in quenched Fe-N steels. This discontinuity is explained by a change in the transformation process. It is proposed that a two-step transformation process occurs in the low carbon region, with the FCC first transforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structure transforms to the BCT structure. The results are explained with the Engel-Brewer theory of valence and crystal structure of the elements. An understanding of the strength of quenched iron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based on interstitial solutes and precipitates.
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Authors: T.G. Nieh, Jeffrey Wadsworth
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