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Grain Boundary Segregation in Zr‐, B‐ and C‐Doped Mo

Published online by Cambridge University Press:  02 July 2020

M. K. Miller
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6136
E. A. Kenik
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6136
K. F. Russell
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6136
A. J. Bryhan
Affiliation:
Applied Materials, Santa Clara, CA, 95054
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Abstract

Molybdenum-based alloys possess a unique combination of physical properties including high strength at elevated temperatures, high thermal conductivity, low coefficient of thermal expansion, and excellent performance in neutron flux environments. However, welds in commercial grade molybdenum alloys typically exhibit low (∼3%) ductility which limits their application. Bryhan has shown that controlled additions of substitutional and interstitial alloying elements can provide almost 20% elongation from gas-tungsten arc welds in 6.35-mm-thick material. Therefore, molybdenum alloys may be considered for use in fusion reactors and other high temperature applications.

The molybdenum alloy was vacuum arc-cast with 0.16 at % Zr intended to getter the O (250 appm) and N (178 appm) impurities together with 53 appm B and 96 appm C intended to strengthen the grain boundaries. The 4-pass welding process was performed on a 6.35-mm plate in a controlled atmosphere chamber where the O, N and water vapor impurity levels were < 10 wppm each.

Type
Applications of Microscopy: Surfaces/Interfaces
Copyright
Copyright © Microscopy Society of America 2001

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References

1. Bryhan, A. J., Joining of Molybdenum Base Metals and Factors Which Influence Ductility, WRC Bulletin 312, Feb. 1986, ISSN 0043-2326.Google Scholar

2. Miller, M. K., Atom Probe Tomography: Analysis at the Atomic Level, Kluwer Academic/Plenum Press, 2000, New York, NY.Google Scholar

3. Research at the Oak Ridge National Laboratory SHaRE User Facility was sponsored by the Division of Materials Sciences and Engineering and the Office of Fusion Energy Sciences, U.S. Department of Energy, under contract number DE-AC05-00OR22725 with UT-Battelle, LLC.