skip to main content

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

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.
 [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:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0022-3115
Grant/Contract Number:
AC52-07NA27344; 13-SI-002
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 479; Journal Issue: C; Journal ID: ISSN 0022-3115
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND RUEL MATERIALS; powder processing; alloys; rapid solidification; solidification microstructure