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Grain Growth in Sintered Uranium Dioxide: II, Columnar Grain Growth
Author(s) -
MacEWAN J. R.,
LAWSON V. B.
Publication year - 1962
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1962.tb11027.x
Subject(s) - uranium dioxide , sublimation (psychology) , materials science , temperature gradient , void (composites) , uranium oxide , pellets , grain boundary , grain growth , melting point , nucleation , composite material , sintering , mineralogy , oxide , uranium , crystallography , grain size , metallurgy , microstructure , chemistry , psychology , physics , organic chemistry , quantum mechanics , psychotherapist
Evidence is presented which shows that columnar grains can be induced to grow in high‐density sintered uranium dioxide specimens by applying a steep temperature gradient at temperatures above 1700°C but below the melting point of 2800°C. Columnar growth apparently is a result of the migration of large transverse voids, whose individual widths define the cross sections of the grains, up a temperature gradient by a sublimation process. The grains grown by this process have a (111) preferred orientation along their columnar axis. A consequence of such void migration in operating fuel elements containing solid UO 2 pellets is the formation of a central void bounded by a region of oxide exhibiting columnar growth.