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Title: Size-dependent microstructures in rapidly solidified uranium-niobium powder particles

Abstract

The microstructures of rapidly solidified U-6wt%Nb powder particles synthesized by centrifugal atomization were characterized using scanning electron microscopy and transmission electron microscopy. Observed variations in microstructure are related to particle sizes. All of the powder particles exhibited a two-zone microstructure. The formation of this two-zone microstructure is described by a transition from solidification controlled by internal heat flow and high solidification rate during recalescence (micro-segregation-free or partitionless growth) to solidification controlled by external heat flow with slower solidification rates (dendritic growth with solute redistribution). The extent of partitionless solidification increased with decreasing particle size due to larger undercoolings in smaller particles prior to solidification. The metastable phases that formed are related to variations in Nb concentration across the particles. Lastly, the microstructures of the powders were heavily twinned.

Authors:
 [1];  [1];  [2];  [3];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Korea Atomic Energy Research Institute, Daejeon (Republic of Korea)
  3. Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1297650
Alternate Identifier(s):
OSTI ID: 1326700
Report Number(s):
LLNL-JRNL-679130
Journal ID: ISSN 0022-3115
Grant/Contract Number:  
AC52-07NA27344; 13-SI-002
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 479; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND RUEL MATERIALS; powder processing; alloys; rapid solidification; solidification microstructure

Citation Formats

McKeown, Joseph T., Hsiung, Luke L., Park, Jong M., Ryu, Ho J., Turchi, Patrice E. A., and King, Wayne E. Size-dependent microstructures in rapidly solidified uranium-niobium powder particles. United States: N. p., 2016. Web. https://doi.org/10.1016/j.jnucmat.2016.06.023.
McKeown, Joseph T., Hsiung, Luke L., Park, Jong M., Ryu, Ho J., Turchi, Patrice E. A., & King, Wayne E. Size-dependent microstructures in rapidly solidified uranium-niobium powder particles. United States. https://doi.org/10.1016/j.jnucmat.2016.06.023
McKeown, Joseph T., Hsiung, Luke L., Park, Jong M., Ryu, Ho J., Turchi, Patrice E. A., and King, Wayne E. Tue . "Size-dependent microstructures in rapidly solidified uranium-niobium powder particles". United States. https://doi.org/10.1016/j.jnucmat.2016.06.023. https://www.osti.gov/servlets/purl/1297650.
@article{osti_1297650,
title = {Size-dependent microstructures in rapidly solidified uranium-niobium powder particles},
author = {McKeown, Joseph T. and Hsiung, Luke L. and Park, Jong M. and Ryu, Ho J. and Turchi, Patrice E. A. and King, Wayne E.},
abstractNote = {The microstructures of rapidly solidified U-6wt%Nb powder particles synthesized by centrifugal atomization were characterized using scanning electron microscopy and transmission electron microscopy. Observed variations in microstructure are related to particle sizes. All of the powder particles exhibited a two-zone microstructure. The formation of this two-zone microstructure is described by a transition from solidification controlled by internal heat flow and high solidification rate during recalescence (micro-segregation-free or partitionless growth) to solidification controlled by external heat flow with slower solidification rates (dendritic growth with solute redistribution). The extent of partitionless solidification increased with decreasing particle size due to larger undercoolings in smaller particles prior to solidification. The metastable phases that formed are related to variations in Nb concentration across the particles. Lastly, the microstructures of the powders were heavily twinned.},
doi = {10.1016/j.jnucmat.2016.06.023},
journal = {Journal of Nuclear Materials},
number = C,
volume = 479,
place = {United States},
year = {2016},
month = {6}
}

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