ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORr
proposed use of zirconium metal as o scavenger (to
replace most of the hydrogen processing) has shown
promise on a small scale; and rapid electrolytic
deposition of iron and nickel from the ZrFd-base
mixtures appears to be feasible. It is anticipated
that the price of purified tdaZrF, and NaF-ZrF,-UF,
mixtures may be halved in the next few months,
SOLID PHASE STUDIES IN THE NaF-ZrFA-UF,
SYSTEM
C, J. Barton
R. E, Moore R. E. 'I'homa
Materials Chemistry Division
G. D, White, Metallurgy Division
H. Insley, Consultant
Studies of the NoF-ZrF,-UF, system were initi-
ated after the solid phase studies In tho NaF-ZrF,
binmy system were coinpleted. The solid phases
present in both the slowly cooled and the quenched
samples were studied by x-ray diffraction and
petrographic analysis techniques. I'he study of
the NaF-UF, system was suspended, except for
some visual-observation experiments, iind will be
resumed when time permits.
Visual-observation experiments (cf. section below
61
on Visual Observation of Melting Temperatures in
the NoF-UF, System"), together with petrographic
studies of slowly cooled NaF-UF, compositions,
demonstrated that the compound previously desig-
nated1t283 as NaUF5 is a congruently melting com-
pound Na,U8F, that is anologclus to the Na,Zr,F,
c~mpound.~ Quenching experiments wibh ternary
compositions on the join Na,LI,F, l-Nn9Lr8F4
show that this join comprises a completely (or
nearly completely) miscible series, with liquidus
temperatures descending from 722°C at the uranium
compound to 520°C. at the zirconium compo~nd.~
Earlier thermal analysis data and filtration experiment~~'~
demonstrated hat there is another
series af complete solid solutions along the join
. . .
'W. R. Grimes et a/., ANP Quar. PTog. Rep. Mar. 10,
1951, ANP-60, p 129.
2W. H. Zochariasen, /. Am. Chhpn. SOC. 70, 2147 (1948).
3C. A. Kraus, Phuse Dingroins of Some Complex Salts
of Urmzium with Halides o the Alkali and Alkaline Earth
Mctds, 14-251 (July 1, 19 A 3).
,R. E. Thomn, et al., ANP ua7. Prog. Rep. June 10,
1954, ORNL-1729, Fig. 4.1, p $1,
J. BQF?rJn, 5. A. Royer, and R. J. seil, ANP ~ m 7 .
5 ~ .
Piog. Rep. Dec. 10, 1953, ORNL.-1649, pp 50 and 55.
6C. J. Bartan and R. J, Sheil, ANP qua^. Prog. Rep.
Mar. 10, 1954, ORNL-1692, p 54.
54
Na3UF -Na3ZrF7, with the high liquidus tempera-
ture (8JO°C) at the zirconium compound and the low
liquidus temperature (628OC) at the uranium eom-
p~uwd. In order to study equilibrium relationships
in the region between these two solid solution joins,
a series af nine compositions equally spaced along
the Na,ZrF,-No,lJF, join was prepared. Phase
annlyses on completely crystallized preparations
of these compositions indicate that Na,ZrF6 and
Na2UF6 do not exist in equilibrium with each other
and with liquid, Instead, the join between Na,ZrF,
and Na2UF6 crosses :he two three-phase triangles
huving their canimon base oil the Ma,ZrF7-Na9U,F,
line and their apexes at Na,ZrF6 and Na,UF,.
Quenching experiments are being made for estab-
lishing liquidus relationships and boundary curves
in this area.
Four ternary mixtures were prepared in order to
obtain a preliminary indication of equilibrium rela-
tionships in other parts of the system. The com-
positions of these mixtures are given in Table 5.1.
Identification, by x-ray diffraction and petrographic
techniques, of the phases in completely crystal-
lized preparations uf the mixtures indicated that the
compound N O ~ Z ~ occupies ~ F , ~ a small primary
phase area contiguous to the primary phase fields
of the NaqZr,F4 ,-NarU8F4 and the ZrF,-UF,
solid solution series. It also appears that the
primary phase field of the ZrF,-UF, solid solution
series is contiguous to the primary phase field of
the Na9ZrgF4,-Na9UBFdl solid solution series
along ths greater part of the boundary curve that
enters the ternaiy system at the Na9U,F,l-UF,
eutectic (42 mole 5% NaF-58 mole % UF, melting
paint 680°C), follows approximately the 50 mole %
NaF ioiri for most of its course, and leaves the
ternary system at the Na,Zr,F,,-Nn,Zr,F ,9 eutec-
tic (approximate!y 50 mole % NaF--50 mole 76
ZrF,, melting point 510°C). 7he mixtures listed
in Table 5.1 will be used for quenching experiments
Sample ......
Designation NQF
.................. ~~
Composition (mole %)
Zr F, F4
T I 45 53 a
T2 41 55 4
T3 42 48 10
T4 48 39 13