Seven Years of Uranium Alloy Development at Weldon Spring, 1959/1966. Page: 40 of 47
This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
at 600*C. produced rod shaped precipitates both within the grains and at the
grain boundaries. These precipitates had a particular orientation with respect
to the important crystallographic planes of the uranium lattice and appeared to
grow at dislocations associated with slip twinning planes of the uranium matrix.
This was an interesting observation suggesting that there might indeed be some
possible effects of precipitates on dislocation motion.
Another study, this time of UAl2, was made as an aid to the program to define
the equilibrium diagrams of the quaternay system, U-Fe-Si-Al. The electron probe,
as has been mentioned earlier, had been unable to determine the limit of solid
solubility of aluminum in the uranium matrix because of a fine precipitate
existing throughout the samples. A transmission picture with the electron
microscope showed that the precipitate was very fine indeed,'-but the X-ray
diffraction data purporting to identify its structure proved to be perplexing.
The interpretation of the Laue pattern indicated that the compounds should be
UAl3, whereas the content of aluminum in the sample (2,000 ppm) was about 1% of
the minimum quantity of aluminum necessary for the existence of UAl3 (at least
as far as our present knowledge of the binary diagram is concerned). Confusion
with some other structure isomorphous with UAl3 did not appear to be a hopeful
explanation as the only such structure known is an antimony compound which does
not appear likely in this circumstance. This confusion is, therefore, still
unresolved and deserves further work.
Mechanisms of Mechanical-Flow in Uranium
Further experience with the microscope was gained in examining the structures
at high magnification existing in uranium tensile specimens after fracture at
three temperatures. namely, 25, 300, and 5000C.29,34 Definite differences in
the mechanics of flow were observed. The room temperature sample showed that
deformation had been by the formation of twins and by concentration of dis-
locations. It was possible to define the twinning and reciprocal twin planes
from the x-ray diffraction pattern in relation to the axis of the specimen and
the calculated amount of shear. At 300*C., flow also took place by twinning
and the number of dislocations visible was very much less. At 500"C., however,
the deformation was by slip with the crystal sections on either side of the
slip bands remaining relatively unchanged in orientation. The slip bands
themselves were revealed in sufficient detail to show the density of
dislocations within them.
To date, the ambition of observing the actual motion of dislocations when under
stress and thermal gradient has not been experimentally achieved. The experi-
mental details of applying a stress to a foil sufficiently thin to be trans-
lucent to electrons have not been successfully resolved. It does appear,
however, that this is a fruitful area for further work and that experiments of
this nature are necessary if a true understanding of the resistance to swelling
under irradiation is to be achieved.
Here’s what’s next.
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Fellows, J. A. Seven Years of Uranium Alloy Development at Weldon Spring, 1959/1966., report, January 1, 1966; Weldon Spring, Missouri. (https://digital.library.unt.edu/ark:/67531/metadc1033773/m1/40/: accessed March 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.