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ANP PROJECT PROGRESS REPORT
THE SYSTEM RLF-UF,
H. A, Friedman
R. E. Moore
The system RbF-UF, has been investigated
recently because of its importance in the qua-
ternary fuel fystem NaF-RbF-ZrF,-UF,. The
earlier work of Blakely et aL3 has been largely
confirmed by thermal analyses of slowly cooled
melts. In addition to the compounds originally
reported, however, there is an incongruent com-
pound 7RbF-6UF4.
Quenching experiments on the system are now
under way, but the work is not yet far enough
advanced to warrant presenting a phase diagram of
the system, Petrographic examinations of a
series of quenched samples containing 33.3 mole
% UF, indicated that a rapid inversion of the
compound 2RbF*UF, occurs at some temperature
below 572°C. The congruent melting point of
RbF*UF, (727OC) was confirmed by petrographic
examination of a series of gradient-quenched
samples containing 50 mole % UF,. The compo-
sition of an incongruent compound previously
thought to be RbFJUF, has now been established
as RbF*3UF4 by the observation of single-phase
material in a series of equilibrated and quenched
samples containing 75 mole % UF,. This phase
is not stable above 714OC. In mixtures Con-
taining between 50 and 100 mole % UF, two
phases, in addition to RbF4UF4, have been
observed in both slowly cooled and quenched
samples. One phase contains more than 80 mole
% UF ,while the other phase contains between
50 and166.7 mole % UF,.
THE SYSTEM RLF-ZrF,
R. E. Moore
Several revisions have been made in the tenta-
tive diagram presented previously for the RbF-
ZrF, system.4 The revised diagram is given in
Fig. 2.1.4.
Visual observation experiments have shown that
the eutectic between 2RbF*ZrF, and SRbFJZrF,
contains about 42 mole % ZrF, and melts at about
41OOC. Results of quenching experiments had
indicated previously that the eutectic contained
3J. P. Blakely et ale, ANP Quar. Prog. Rep. June 10.
1951, ANP-65, p 87, Fig. 4.1.
A. Friedman and R. J. Sheil, ANP Qum. Prog.
Rep. March 10, 1956, ORNL-2061, p 72, Fig. 4.1.
84
38 mole % ZrF, and melted at 375OC. It is now
apparent that 375OC is the lowered rapid inversion
temperature of 2RbF*ZrF, rather than the eutectic
temperature. In the region between 37 and 44.5
mole % ZrF, 2RbF*ZrF, appears optically to be
like quench growth at all temperatures above the
lowered inversion temperature. This accounts for
the misinterpretation of the quenching data.
Petrographic examination of a series of samples
containing 48.3 mole % ZrF, established that
5RbF4ZrF4 is the primary phase; the iiquidus
temperature is about 396OC, and the solidus
temperature is 390°C. Thus, the eutectic between
5RbF4ZrF4 and RbFOZrF, contains about 48.5
mole % ZrF, and melts at 390OC.
Examinations of slowly cooled preparations have
shown the existence of a compound containing
more than 50 mole % ZrF,. This compound has
been tentatively identified as RbF-2ZrF4 by the
observation of nearly single-phase material in a
series of equilibrated and quenched samples
containing 66.7 mole % ZrF,. This compound
melts incongruently to ZrF, and liquid at 447OC.
THE SYSTEM NaF-RbF-ZrF,
R. E. Cleary5 H. A. Friedman
A phase diagram of the fuel solvent system
NaF-RbF-ZrF,, based on thermal analysis of
slowly cooled melts, differential thermal analysis,
and quenching experiments, is shown in Fig. 2.1.5.
Some of the compatibility triangles and quasi-
binary mixtures were reported previously.6 The
present status of the information on the com-
patibility triangles, eutectics, peritectics, and
boundary curves is shown in Fig. 2.1.5. The
locations of the eutectics and the exact paths of
the boundary curves are not considered to be
final in this diagram; they are contingent on
confirmation by quenching experiments.
The phase relationships of the recently dis-
covered compound RbF-2ZrF4 in the ternary
system have not yet been determined. The ter-
nary compounds of the solvent system are:
NaF-RbF-ZrF,, which melts congruently at 615OC;
3NaF*3RbF4ZrF4, which melts incongruently at
45OoC; and NaF*RbF.2ZrF4 which melts congru-
ently at 4600C. A fourth ternary compound with
W
*
50n assignment from Pratt 8, Whitney Aircraft.
'He A. Friedman, ANP Quar. Pmg. Rep. March 10.
1956, ORNL-2061, P 72. -61
0