CONTENTS SUMIMAIY . cvtenirneeieuientioes e enseetesssestanssescessssessssnatesentessersesssusssssasersonsensessensensnsessssssssssessesssssssenes ] I P OAU CION. . ettt st eeteesiseesaee e sbe e saesassenessassasssestosaessnssseeatessasnssssasesnnssaessrants 1 Materials, Methods, and Apparatus .....cccceveiiiccesese et st s ss e 2 General Discussion of the System LiF-UF ,-ThF, and the Limiting Binary Systems .c.eeeviveieeceiicttninnnese it scetessresssstsseseesrastessssessssessasssensestsssnense 2 The 20 Mole % LiF Join and the LiF.4UF ,-LiF-4ThF, (ss) Fractionation Paths ...ttt eesseeceteessassssesseessessssessaessssaessseses 20 P At e e e b s sa e sa e s bt s e e a s e sars s b et et s aeseen savRaarabenarsaten 21 The 53.8 Mole % LiF Join and the 7LiF-6UF4—7LiF-6ThF4 (ss) Fractiongtion Paths ...t scseeniste et e sresaensesssasseresessssssassenssasss nsenassos 21 The 75 Mole % LiF Join and the 3LiF-ThF, (ss) Fractionation Paths......cccoovenirnerncnnc. 21 Relations Between the Solid SolUtionS ... cuiieeeuinienrcctnice e e sve st esnaaes 31 ACKNOWIEAGMENTS ... .ottt rte e sttt e sieerbe e e sert e ses eraesbe s st esen sasbeesaensene 34 APPENAIX .cueerinriiieiiiciiriinierereeteeesitassreesresesaesstessasts s aes s sssassensaessasre seresssars senesenesatesessraeneeannrases 43 ORNL-2719 Chemistry-General TID-4500 (14th ed.) Contract No. W-7405-eng-26 REACTOR CHEMISTRY DIVISION PHASE EQUILIBRIA IN THE SYSTEMS UF —ThF , AND LiF-UF -ThF C. F. Weaver R. E. Thoma H. Insley H. A. Friedman This document has been reviewed and is determined to be DATE ISSUED AUl L4 1959 OAK RIDGE NATIONAL LABORATORY Ock Ridge, Tennessee operated by UNION CARBIDE CORPORATION for the U.S. ATOMIC ENERGY COMMISSION PHASE EQUILIBRIA IN THE SYSTEMS UF ,~ThF ; AND LiF-UF ;-ThF C. F. Weaver R. E. Thoma SUMMARY As part of a study of materials potentially useful as fluid fuels for high-temperature reactors, equilibrium diagrams for the condensed systems UF,-ThF, and LiF-UF ,-ThF, have been de- termined. Both thermal analysis and quenching techniques were used, with phase identification accomplished by petrographic and x-ray diffraction analysis. A complete series of solid solutions without maximum or minimum is formed by UF, and ThF,. The system LiF-UF,-ThF, contains no ternary compounds but does contain four ternary solid solutions. The compounds LiF+-4ThF, and LiF+-4UF, form a continuous series of solid solutions, as do the compounds 7LiF <6 ThF, and 7LiF-6UF,. A series of solid solutions exists having compositions at 33Y% mole % LiF between LiF-2ThF, and 23 mole % UF,. Another series of solid solutions exists having compositions at 75 mole % LiF between 3LiF+-ThF, and 15.5 mole % UF ;. Seven primary-phase fields appear in the system, those which are solid solutions being indicated by (ss): LiF, 4LiF-UF4, 3LiF-Th(U)F, (ss), 7LiF-6ThF ,~7LiF-6 UF, (ss), LiF-2Th(U)F (ss), LiF+4ThF ,-LiF-4UF, (ss), and UF ,-ThF, (ss). Phase relations were established trom the liquidus to about 300°C. The three invariant points which occur are the following: peritectic, 19 mole % UFA, 18 mole % ThF,, 609°C; peri- tectic, 20.5 mole % UF4, 7 mole % ThF ,, 500°C; and eutectic, 26 .5 mole % UF4, 1.5 mole % ThF4, 488°C. The solid phases taking part in the invariant reactions are the following: peritectic point at 609°C: LiF'4ThF4—LiF~4UF4 (ss) containing 28 mole % UF,, LiF:2Th(U)F, containing 23 mole % UF,, and 7LiF« ThF ,—7LiF.6UF, con- taining 23 mole % UF ,; peritectic point at 500°C: LiF, 7LiF«6ThF ~7LiF.6UF, (ss) containing 31 mole % UF,, and 3LiF-Th(U)F, (ss) containing 15.5 mole % UF,; eutectic point at 488°C: 4LiF-UF4, LiF, and 7LiF+6 ThF4—7LiF-6UF4 (ss) containing 42.5 mole % UF . The refractive indices of the ternary solid solutions were determined as functions of compo- sition and used for an optical analysis of the solid solutions when they occurred with other phases. This information made possible the H. Insley H. A. Friedman construction of tie lines, fractionation paths, and compatibility triangles for the three ternary invariant points. INTRODUCTION Several years ago, R. C. Briant of the Oak Ridge National Laboratory suggested the use of a molten mixture of UF, and ThF, together with fluorides of alkali metals and beryllium fluoride or zirconium fluoride as a potential fuel for a high-temperature, low-pressure nuclear reactor.! A systematic study at ORNL during the past several years has developed molten salt mixtures whose chemical and physical properties seem to suit them for use as fuels in U235 burner re- actors,2 in plutonium burner reactors, and in one-region U233 breeder reactors and as blankets in two-region U233 breeder reactors. Nuclear reactor designs have been proposed which would utilize mixtures of Li’F, BeF,, ThF,, and UF, as fuels.3-3 Little is known concerning the phase relation- ships of the system LiF-Ber-UF4-ThF4 except that solid solutions involving LiF, UF,, and ThF, occur as primary and secondary phases at low UF, and ThF, concentrations. Phase diagrams of the limiting binary systems LiF-BeF (ref 6), LiF-UF, (ref 7), and LiF-ThF, (ref 8) YA, M. Weinberg and R. C. Briant, Nuclear Sci. and Eng. 2, 797-803 (1957). 2E. S. Bettis et al., Nuclear Sci, and Eng. 2, 804-825 (1957). 3J. K. Davidson and W. L. Robb, A Molten Salt Thorium Converter for Power Production, KAPL-M- JKD-10 (1956). 4L. G. Alexander et al., ‘‘Conceptual Design of a Power Reactor,”” chap 17 of Fluid Fuel Reactors, Addison-Wesley, Reading, Mass., 1958, 5L. G. Alexander, ‘‘Nuclear Aspects of Molten-Salt Reactors,’’ chap 14 of Fluid Fuel Reactors, Addison- Wesley, Reading, Mass., 1958. ¢R. E. Thoma, Pbhase Diagrams of Nuclear Reactor Materials, ORNL-2548, 7C. J. Barton et al., J]. Am, Ceram. Soc. 41(2), 63-69 (1958). 8R. E. Thoma et al., ‘‘Phase Equilibria in the Fused Salt Systems LiF-Thl"'4 and NaF-ThF4," J. Pbys. Chem. (in press). have been published. The systems BeF,-UF, (ref 9) and LiF-BeF,-UF, (ref 10) have been investigated at the Mound Laboratory., Results of phase equilibrium studies of the systems BeF,- ThF, and LiF-BeF,-ThF, will soon be reported by the authors. Preliminary diagrams of these systems are in the literature.'1+12 The system Bef ,-UF ,-ThF, has not, to our knowledge, been investigated. The remaining systems, UF“-ThF4 and LiF-UF ,-ThF,, are the subject of this report. Preliminary diagrams of these systems have been reported by the authors.'2:13 As is to be expected from the known similarities in the parameters of the unit cells of ThF4 and UF4 (refs 14 and 15), a salient characteristic of the condensed systems UF,-ThF, and LiF-UF,-ThF, is the extensive formation of solid solutions. MATERIALS, METHODS, AND APPARATUS The lithium fluoride used in this investigation was reagent grade, obtained from Foote Mineral Company and from Maywood Chemical Works. The thorium tetrafluoride was obtained from lowa State College and from National Lead Company. The wuranium tetrafluoride was obtained from Mallinkrodt Chemical Works. No appreciable impurities were found in the uranium tetrafluoride or thorium tetrafluoride by spectrographic, x-ray diffraction, or microscopic analysis. The phase equilibria data were obtained by thermal analysis of slowly cooled melts and by identifying the phases present in mixtures which had been equilibrated and quenched. Because uranium and thorium fluorides are easily converted ). F. Eichelberger, E. F. Joy, E. Orban, T. B. Rhinehammer, and P. A. Tucker, unpublished work. 10, F, Eichelberger, D. E. Etter, C. R. Hudgens, L. V. Jones, T. B. Rhinehammer, P. A, Tucker, and L. J. Wittenberg, unpublished work. 1w, R. Grimes et al., '"Chemical Aspects of Molten- Fluoride Reactor Fuels,’”’ chap 12 of Fluid Fuel Re- actors, Addison-Wesley, Reading, Mass., 1958, 12”Sl.npplement to ‘Phase Diagrams for Ceramists’’’ (compiled by M. Levin and H. F. McMurdie), American Ceramics Society, Inc., Easton, Pa. (in press). ]3R. E. Thoma et al., MSR Quar. Prog. Rep. Jan 31, 1958, ORNL.2474, p 81, 'I4W. H. Zachariasen, X-Ray Diffraction Studies of qagzjg)ellaneous Uranium Compounds, MDDC-1152 (June 155, J. Katz and E, Rabinowitch, The Chemistry of Uranium, NNES VIHI-5, McGraw-Hill, New York, 1951. to oxides or oxyfluorides at elevated temperatures, it was necessary to remove small amounts of water and oxygen as completely as possible from the starting materials. To facilitate the removal of these substances, ammonium bifluoride was added to the mixtures of lithium fluoride, thorium fluoride, and uranium fluoride before initial heating in the thermal analysis experiments, While the mixtures were being heated the water was evaporated from the system, The oxides were converted by reaction with the ammonium bifluoride to products which have not yet been identified but which are likely to be ammonium fluometallates.'6+17 Upon further heating, the “ammonium fluometallates’® decomposed to form the metal fluorides. These same mixtures were later used in the quenching experiments, The phases were identified by petrographic and x-ray diffraction techniques. These methods for characterizing phases, as well as a description of the apparatus used for preparing and annealing samples, were reported previously,”+8:18-21 GENERAL DISCUSSION OF THE SYSTEM LiF-UF ,-ThF, AND THE LIMITING BINARY SYSTEMS The phase diagram of the condensed ternary system LiF-UF4-ThF4 is shown in Fig. 1, and a photograph of a three-dimensional model22 of the system is shown in Fig. 2. The associated binary systems are shown in Figs. 3-5. One metastable compound (3LiFoUF4) and three incongruently melting compounds (4LiF-UF4, 7LiF-6UF,, and LiF.4UF,) are formed in the system LiF-UF ,. Optical properties, except those of 3LiF-UF4, and x-ray diffraction data for these ;gmsza Quar. Prog. Rep. April 30, 1959, ORNL-2723, p 93. 17, J. Sturm, Oak Ridge personal communication. 8¢, J. Barton et al., J. Phys. Chem. 62, 665 (1958). 19R. E. Thoma et al.,, J. Am. Ceram. Soc. 42(1), 21-26 (1959). 20H. A. Friedman, Techniques for Phase Ceram. Soc. (in press). 21p, A. Tucker and E. F. Joy, Am. Ceram. Soc. Bull. 36(2), 52-54 (1957). Model constructed by C. Johnson, summer participant ot ORNL, 1958. National Laboratory, **Modifications of Quenching Equilibrium Studies,”” J. Am. ThE, (AL UNCLASSIFIED ORNL-LR-DWG 28245AR2 PRIMARY-PHASE AREAS (@) UF,-ThE, (ss) (b) LiF-4UF,-LiF-4ThF, (ss) () LiF-2Th(UIF, (ss) (d) 7LiF-6UF,-7LiF-6ThE, (ss) (e) 3LiF-Th(U)F, (ss) (f) LiF TEMPERATURE IN °C COMPOSITION IN mole %% LiF- 4ThE, LiF'2ThF4 P87 N AN 7LiF-6ThF, P 762 A \ (b P 597 Ay £ 565 00 3LiF-ThF4 £ 568 A A S pAY o) Q P 609 @)\ 3 0 AD\, B RS 6o T NP 500 % 25 W\ T O \ o) \ \\ , VAR ARWNAN Y 845 aLiF-UF,” £500" '£490 P 610 PTT5 LiF-4UF 7LiF-6UF, Fig. 1. The System LIF-UF4-TI1F4. UNCLASSIFIED PHOTO 32550 + ® TLiF-gu, Lif +71k. if 6'."‘ ]h’“‘“‘ + LF-4uf, UF4UE, + u, (¢ LiF-4UF, 300 TLF-8UF, Fig. 2. Three-Dimensional Model of the System LiF-UF,-ThF,. TEMPERATURE (°C) TEMPERATURE (-C) UNCLASSIFIED ORNL —LR-DWG 17457 1100 / A {000 / 200 v : / 700 \ / 600 \ / u~ 500 \/ 5 u yod © < 4LiF UF4/ = W ~ - 400 LiF 10 20 30 40 50 60 70 80 90 UF, UF, (mole %) Fig. 3. The System LiF-UF .. UNCLASSIFIED ORNL-LR-DWG 26535A el T T T T 1 & | i N ‘ 5 UNCLASSIFIED ORNL~-LR-DWG 27913R 1050 ! R ! 1200 | : 950 ———-L—u—r-—--wa E | ! [L - o ‘ l ‘ 4 T T 1100 tremmme '~ LiQuID 1 | f 1 T & ‘"%, $ i | 850 ha——— : ; A“,k*l-__. U SUN— 2 \T 1 T / \ { 51000 |- -~—*LIQUID + ThE, - UF, SOLID SOLUTION : ui 750 ——1 /- —— o . ; ; \ ‘ / = 900 |-— — A-j«‘m-;,-ug, SOLID SOLUTION ; i | | . - | N\ ! NN RS S I T . ! : 850 P\ g . soo L IS N N N VY cun m iR 4_ T, 10 20 30 40 50 60 70 80 90 UF, 550 F—F = e RIS y 3LiF-ThE,—| 7LiF -6ThE,— LiF-2ThE, — E - | UFy {mole %) i : 250 | I l LiF 10 20 30 40 50 60 70 80 90 ThE‘ ThE, (mole %) Fig. 4. The System LiF-ThF, Fig. 5. The System ThF4-UF4. compounds are shown in Tables 1 and 2, re- A complete series of solid solutions without spectively. The compound 4LiF-UF, has a lower maximum or minimum is formed in the system limit of stability at 470°C. The compositions and UF ,-ThF,. The optical properties of these solid temperatures of the three peritectic invariant solutions are shown in Table 1 and Fig. 6. The . points and the eutectic invariant point are (1) peritectic: 26 mole % UF ,, 500°C; (2) eutectic: NeLASSFED 27 mole % UF,, 490°C; (3) peritectic: 40 mole % ' ORNL-LR—DWG 279145 - UF,, 610°C; (4) peritectic: 57 mole % UF,, 775°C. | A | One congruently melting compound (3LiF-ThF4) and three incongruently melting compounds (7LiF-6 ThF,, LiF2ThF,, ond LiF.4ThF,) are formed in the system LiF-ThF ,. Optical properties and x-ray diffraction data for these compounds are shown in Tables 1 and 2, respectively. The compositions and temperatures of the three peri- tectic and two eutectic invariant points and one congruent melting point are (1) eutectic: 23 mole | [ % ThF,, 565°C; (2) congruent melting point: 25 rag b | | x mole % ThF,, 573°C; (3) eutectic: 29 mole % The 20 4%‘: (mo!e?)eo 80 U ThF,, 568°C; (4) peritectic: 30.5 mole % ThF,, 4 7 597°C; (5) peritectic: 42 mole % ThF4, 762°C; Fig. 6. Indices of Refractlon vs Composition for ThF ;- (6) peritectic: 58 mole % ThF,, 897°C, UF, (ss), INDEX OF REFRACTION Table 1. Optical Properties of LiF-UF4, LiF-ThF4, and UF4-ThF4 Solid Phases® Compound Optical Character Sign Optic Angle N,or N, N, or N.y 4LiF.UF, Biaxial + 45° 1.460 1.472 7LiF-6UF4 Uniaxial - 1.554 1.551 LiF-4UF, Biaxial - 10° 1.584 1.600 3LiF~ThF46 Biaxial - 10° 1.480 1.488 7LiF-6ThF4 Uniaxial + - 1,502 1.508 LiF«2ThF, Uniaxial - 1.554 1.548 LiF«4ThF 4" Biaxial - 10° 1.528 1.538 UF4-ThF4 (ss€) (70% UF ) Biaxial - 60° 1.536 1.586 (60% UF ) Biaxial - 60° 1.530 1.580 (50% UF ) Biaxial - 60° 1.516 1.566 (40% UF ;) Biaxial - 60° 1.510 1.560 % Data taken from R. E. Thoma et al., *Phase Equilibria in the Fused Salt Systems LiF-ThF4 and NaF-ThF4," J. Pbys, Chem, (in press); H. Insley et al., Optical Properties and X-Ray Diffraction Data for Some Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct. 23, 1956); and L. A. Harris, G. D. White, and R. E. Thoma, ** Analysis of the Solid Phases in the System LiF-ThF4," J. Pbys., Chem. (in press). . bThis routinely observed biaxiality appears to be produced by strain in the 3Li|=-'l'hl=4 and LiF-4ThF4 crystals, inasmuch as the crystal type is tetragonal as determined by x-ray diffraction measurements, ©Solid solution. Table 2. X-Ray Diffraction Patterns for the Solid Phases Occurring in the Systems LiF-ThF, ond LiF-UF ;* 3LiF-ThE, TLiF-6THF, LiF-2ThE, LiF 4ThF, ALiF-UF, ILiF-UF, TLiF-6UF, LiF-4UF, &) 1, 4R v, AR) 1, 4R i, 4R) i, 4R 1”1, AR) 1, 4R) i, 6.42 00 607 15 7.97 5 8.4 3 567 0 49 0 66l 6 102 8 a.46 00 591 20 637 0 776 3 546 25 480 15 597 20 633 12 4.37 00 536 % 39 00 651 5 513 70 44 100 582 15 607 5 2.62 8 5.5 15 3.8 65 580 25 493 00 4.34 00 5.2 % 573 2 3.09 55 495 325 5 482 5 4ss VI X 15 515 0 a9 8 2.866 0 485 20 3 5 4m 70 444 00 39 8 465 0 470 2 2.788 0 475 00 297 0 3.8 00 42 7 340 80 437 13 425 %0 2.542 2% 400 85 282 25 240 0 382 0 340 10 395 55 3.88 2 2.327 0 392 15 2675 7 325 0 355 0 304 25 385 13 37 100 2,189 0 374 15 2528 0 292 25 203 0 207 50 368 0 352 %0 2,104 65 355 65 2338 5 282 2% 289 25 2.4 80 3.49 B 306 8 2,071 2% 344 o 2s 85 2,603 10 2866 3 27m 3 33 9 343 8 2,036 0 33 70 2053 0 2398 0 2747 0 259 B 3s 70 306 12 1.959 3.2 60 200 65 2137 25 2468 o 2169 15 3.07 0 284 40 1933 60 303 00 1787 7 205 35 2398 20 2.083 s 29 95 27l 55 1.877 25 284 35 L0 10 2000 0 2= @ 2085 s 27 0 2542 8 7 25 2747 25 1689 5 2018 0 216 5 194 50 2707 3 2.3% 10 1,743 % 257 20 1603 5 2005 B 2,074 0 1913 25 2542 25 2300 10 1.701 35 243 0 1509 5 9w 0 202 20 1860 0 2350 13 2.2 8 1.66) o 239 10 1.820 0 1872 0 L75 25 228 25 2.000 10 1.618 0 2302 20 1778 3 1.83% 25 1723 2% 2.264 13 2088 3 1.547 I/ 237 20 1.725 5 1.685 25 2184 o 206 &0 1.520 35 2008 5 1719 5 1.662 8 2097 B e 50 2.001 15 1.666 5 1.646 0 2,060 30 1.888 2 1.892 55 1.605 5 1.599 8 2.047 5 1819 8 1.859 15 1.595 5 1.993 B 1767 25 1.804 15 1.563 5 1972 2 1.680 15 1.947 25 1.653 20 1.924 15 1.600 20 1.909 30 1.854 a5 1.825 2 1773 2 1,757 2 1.709 15 1.680 15 1.625 15 1.579 25 1.562 8 *Dota taken from R, E. Thoma et al., *Phoso Equilibrium in the Fused Salt Systems LiF-ThF , and NoF-ThF " . Phys. Chem. (in pross); H. Insloy et al., Optical Properties and X-Ray Diffraction Data for Some Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct, 23, 1956); L. A. Harris, G. D. White, and R. E. Thoma, *‘Anclysis of the Solid Phoses in the Systom LiF-ThF ' J. Pbys. Chem. (in press); and L. A. Harris, Crystal Structures of 7:6 Type Compounds of Alkali Fluorides with Uranium Tetrafluoride, ORNL CF.58.3.15 {March 6, 1958). - equilibrium phase diagram is based on the thermal analysis data shown in Table 3 and the results of quenching studies shown in Table 4, The system LiF-UF ,-ThF, contains no ternary compounds but does contain four ternary solid solutions. The compounds LiFotiTI*aF“--LiF-AUF4 form a continuous series of solid solutions, as do the compounds 7LiF-6ThF4-7LiF-6UF4. A series of solid solutions exists having compo- sitions at 331/3 mole % LiF between LiF.2ThF, and 23 mole % UF4. Another series of solid solutions exists having compositions at 75% LiF between 3LiF-ThF4 and 15.5 mole % UF4. The joins containing these solid solutions are described in detail in sections below. Seven primary-phase fields appear in the system: LiF, 4LiF.UF, 3LiF-ThF, (ss), 7LiF«6 ThF ,— JLiF-6UF, (ss), LiF2ThF, (ss), LiF-4ThF ,- LiF-4UF4 (ss), and ThF4-UF4 (ss). Phase re- lations were established from the liquidus to about 360°C. Three invariant points occur: peri- tectic: 20.5 mole % UF4, 7 mole % ThF,, 500°C; eutectic: 26.5 mole % UF4, 1.5 mole % ThF4, 488°C; peritectic: 19 mole % UF,, 18 mole % ThF,, 609°C. The reactions which take place at Table 3. Thermal Analysis Data for the Systems UF4-TI1 F4 and LiF-Th F4-UF4* Interpretation Key | = liquidus a = boundary between UFA-Th F4 (ss) and LiF+4UF ,~LiF-4Th F4 (ss) primary-phase fields b=4LiF.U Fq decomposition ¢ = boundary between LiF°2ThF4 (ss) and LiF°4UF4-LiF'4Th Fy (ss) primary-phase fields d = ternary eutectic e= LiF, 3Li|""°T|'1F4 (ss), 7LiF-6UF4-—7LiF'6Th F4 (ss) peritectic f = boundary between 3LiF+*Th F4 (ss) and 7LiF°6UF4-7LiF°6Th Fy (ss) primary-phase fields g = boundary between LiF and 7LiF'6UF4-7LiF°6Th F4 (ss) primary-phase fields h = liquid disappearance at { i= 3Li|'-'°ThF4 (ss) exsolution k = liquid disappearance at m m = boundary between LiF and 3LiF*Th F4 (ss) primary-phase fields s = solidus Composition Temperature Interpretation Composition Temperature Interpretation (mole %) (°C) (mole %) (°c) UF4-ThF4** LiF-Tl1F4-UF4 70-30 1025 20-10-70 747 1023 750 1005 20-20-60 965 1 985 951 | 60-40 1051 | 780 a 1045 | ' 785 a 1010 20-30-50 982 | 993 941 | 955 825 a 50-50 1085 | 817 a 1080 | 20-40-40 805 a 1050 | 795 a 1035 20-50-30 915 1017 837 a 1005 832 a 990 825 a 985 20-60-20 835 a 40-60 1040 | 832 a 1035 20.70-10 855 a 1022 860 a 1005 33)4-33)4-33), 859 o 990 846 a 960 830 a 815 a LiF-ThF“-UF4 815 a 20-10-70 962 | 33),-46%-20 478 b 960 | 430 *In general, more than one thermal analysis was made for each nominal composition, All the thermal breaks are listed, but it is not intended to imply that they all occurred on a single cooling curve, The variation in temperatures associated with the same phenomenon is believed to be caused by supercooling effects. **Each of these slowly cooled melts contained only one phase according to x-ray diffraction and petrographic analysis, indicating that there is no miscibility gap in the system UFA-Th F4. 8 13 Table 3 (continued) Composition Temperature . Composition Temperature . (mole %) (°C) Interpretation (mole %) (°C) Interpretation 33)%-46%-20 320 40-30-30 823 300 470 b 33%-51%-15 890 a 458 b 870 a 40-40-20 902 852 a 902 33),-56%-10 91 | 861 l 961 | 860 1 875 a 590 875 a 588 665 c 467 b 663 c 423 960 | 40-50-10 865 ] 956 | 860 | 875 a 855 1 875 a 675 c 695 c 675 c 692 c 50-10-40 755 | 35-20-45 895 | 755 ! 893 I 482 d 805 a 480 d 805 a 420 800 a 428 799 a 50-15-35 635 480 d 483 d 423 482 d 35-45-20 928 430 928 50-25-25 803 l 850 a 490 d 850 a 490 d 845 a 451 845 a 442 40-10-50 840 l 53.8-6.2-40 720 | 840 | 715 | 777 482 d 777 450 475 b 53.8-10-36.2 717 ! 445 717 | 40-20-40 825 | 481 d 800 445 790 53.8-11.2-35 730 | 782 625 467 b 490 d 428 485 d 40-30-30 863 | 441 853 1 430 825 53,8-13.2-33 725 ! Table 3 {continued) 10 Composition Temperature ] Composition Temperature ] (mole %) ©C) Interpretation (mole %) (°C) Interpretation . 53.8-13.2-33 725 I 57-15-28 467 b 487 d 57-21.5-21.5 717 | 485 d 690 436 481 d 53.8-15-31.2 726 I 481 d 718 | 458 485 d 458 455 57-26-17 708 ! 53.8-18.2.28 740 | 707 | 740 | 496 e 485 d 495 e 485 d 485 d 446 485 d 53.8-23.1-23.1 773 | 427 770 l 57-28-15 733 | 485 d 733 ! 437 500 e 53.8-30-16.2 766 I 499 e 7351 ! 480 d 498 e 480 d 485 d 417 468 b 57-30-13 748 | 53.8.36.2-10 763 | 748 762 I 515 f 517 f 514 f 515 f 487 d 447 485 d 57-4-39 666 ! 422 663 | 57-32-11 750 550 750 535 687 1 493 g 686 | 493 g 521 f 488 d 521 f 480 d 58+22.20 725 | 57-10-33 688 ! 725 I 687 l 490 d 491 d 442 490 d 58-24.18 715 I 470 b 715 ! 470 b 495 e 57-15-28 705 | 480 d 705 I 430 492 g 60-5-35 625 I © 487 d 620 | 483 d 489 d Table 3 (continued) Composition Temperature ] Composition Temperature ) (mole %) °0) Interpretation (mole %) ©0) Interpretation 60-5.35 488 d 60-30-10 685 | 450 670 445 665 435 527 f 60-10-30 655 | 525 f 655 | 420 490 d 60-35-5 726 | 489 d 718 I 489 d 546 f 475 b 546 f 475 b 62-10.28 618 1 465 615 1 462 545 60-15-25 670 | 535 670 | 492 g 490 d 491 g9 489 d 485 d 458 470 b 451 62-20-18 650 | 445 650 ! 60-20-20 678 I 497 678 | 495 495 g 495 495 9 485 d 490 d 485 d 490 d 440 465 b 62.28-10 687 465 b 685 458 675 I 445 665 | 445 587 60-22.18 685 | 525 f 685 | 410 550 t 62.33-5 704 I 495 703 | 492 545 f 485 d 543 f 485 d 64-24-12 652 467 b 625 60.25-15 710 533 f 657 525 f 657 525 f 508 e 523 f 483 d 64-31.5 673 | 470 b 669 | 60-30-10 690 | 544 t 1 Table 3 (continued) Composition Temperature Interoretation Composition Temperature Int toti (mole %) (°C) P (mole %) °C) nterpretation 64-31.5 543 f 69-27-4 540 f 525 69-29.2 612 66-24-10 622 611 620 558 f 567 | 557 f 528 f 70-10.20 495 f 523 h 495 f 517 h 487 d 6629-5 640 I 485 d 640 | 477 b 536 f 462 b 535 f 70.20-10 544 f 530 h 540 f 525 h 524 h 67-26-7 615 521 h 615 520 h 547 f 520 h 542 f 430 68-17-15 592 | 415 592 | 70.24.6 575 | 543 f 575 | 530 f 549 f 512 h 540 f 511 h 70.5-12,5-17 500 e 487 i 500 e 487 i 475 b 430 475 b 68-24-8 610 455 607 450 540 | 442 536 | 441 530 f 400 520 f 70.5-17-12.5 525 f 500 e 520 f 69-4.27 490 9 515 h 487 ] 511 h 480 d 511 h 478 d 475 b 472 b 471 b 467 b 442 445 439 425 71-1.28 507 | 420 489 d 69-27-4 604 | 475 b 600 | 545 549 f 71.2.27 484 d 12 Table 3 (continued) Composition Temperature . Composition Temperature . o Interpretation o Interpretation (mole %) (°C) {mole %) ("C) 71.2.27 475 b 72-8-20 516 | 475 b 508 | 448 508 | 71.5.24 488 d 492 d 485 d 490 d 485 d 450 483 d 72-10-18 560 452 500 e 442 475 b 440 428 435 72-11.17 512 | 71.24.5 560 | 501 e 558 l 500 e 545 h 461 b 544 h 456 535 h 72-12-16 517 | 71.5-1-27.5 484 d 515 | 484 d 508 | 470 b 489 d 455 485 d 71.5-2.26.5 504 441 487 d 428 475 b 72.18-10 530 | 467 b 527 | 451 472 b 72-1.27 762 425 469 b 72,5-1.26.5 480 d 467 b 475 d 463 b 467 b 72.2.26 475 b 467 b 475 b 450 450 73-2-25 485 d 430 476 b 72.3.25 658 475 b 484 d 433 475 b 73-11-16 517 I 462 b 5N f 444 500 e 428 484 d 72-4.24 504 482 d 490 d 469 b 487 d 460 b 445 73-12.15 514 | 72-6-22 487 d 503 e 482 d 477 480 d 477 13 Table 3 (continued) Composition Temperature . Composition Temperature (mole %) (°c) Interpretation (mole %) (°C) Interpretation 73-12-15 460 75-15.10 535 | 439 525 m 415 525 m 412 75-20.5 555 | 73-15.12 517 | 555 | 515 | 550 | 510 f 75-23-2 803 507 f 563 | 505 e 532 s 390 77-15.8 645 74-20+6 535 f 546 | 535 f 545 | 74-24-2 555 f 540 k 553 f 538 k 465 i 77-19-4 575 460 i 575 75-5-20 535 550 | 528 | 550 i 526 | 538 k 489 d 80-10.10 755 487 d 748 445 493 i 431 490 i 75-10-15 535 | 428 527 | 80-15.5 625 | 512 k 625 | 507 k 541 k 442 541 k 432 430 75-12-13 524 I 420 521 [ 415 75-15.10 740 14 s Table 4, Thermal-Gradient Quenching Results for the ThF4-UF4 Liquidus and the LiF-Th F4-U F4 Liquidus? Compos ition Liquidus (mole %) Tempoerafure Primary Phase (°C) UF ,-ThF, 40-60 1053 + 4 UF,-ThF, (ss?) 50-50 1062 £ 3 UF ,-ThF, (ss) 60.40 1053 £ 4 UF - ThF, (ss) 70.30 1053+ 4 UF,-ThF, (ss) UF ,-ThF ,-LiF | 2.23.75 5723 3LiFsThF , (ss) 2-24.74 5623 3LiF*ThF, (ss) 2.2969 594 %3 TLiFs6ThF ,~TLiF+6UF , (ss) 4-19.77 567 £3 LiF 4-27-69 5986 TLiFs6 ThF ,~7 LiF*6UF , (ss) 5.15.80 615+3 LiF 5.19-76 5622 3LiF*ThF (ss) 5.20.75 5623 3LiF*ThF, (ss) 5:24-71 56513 TLiF*6ThF ,~7LiF+6UF , (ss) 22-6.72 504 + 4 LiF 23.1.23.1-53.8 744 %3 LiFedThF ,~LiF*4UF (ss) 24-4-72 495 2 LiF + 7LiFs6 ThF ,~7LiF*6UF , (ss) 25.2.73 49112 LiF + 7LiFs6 ThF ;~TLiF*6UF , (ss) 25-3.72 49512 LiF + 7LiFs6 ThF ,~7LiF+6UF , (ss) 25.25-50 806 13 LiF*4ThF ,~LiF*4UF (ss) 26-2-72 496 12 LiF + 7LiF*6ThF ,~7LiF*6UF ; (s5)° 26,5-1-72,5 495 +2 4LiFeUF, + 7LiFs6ThF ~7LiF*6UF , (ss) 26.5-2-71.5 504 2 4LiF°UF , + 7LiF*6ThF ~7LiF+6UF (ss) 27-1.72 49112 4LiFeUF , + TLiFs6 ThF ,~7LiF*6UF , (ss) 27.2.71 49512 LiF + 7LiF*6ThF ,~7LiF*6UF , (ss) 27.5.1-71.5 49512 4LiFsUF , + 7LiF*6 ThF ,~7LiF-6UF , (ss) 28.1.71 508 £ 2 TLiF+6ThF ,~7LiF*6UF, (ss) 28-10.62 615+3 LiFedUF ,~LiF*4ThF (ss) 28-18.2.53.8 729 %3 LiF+4UF ,~LiF*4ThF (ss) 30.10-60 6332 LiF+4UF ,~LiF*dThF (ss) 30-30-40 859 + 1 LiF+4UF ,~LiFe4ThF, (ss) 30-50-20 968 + 4 UF 4-Th Fq (ss) Table 4 (continued) 1 ] 16 Composition Liquidus (mole %) Tem%erafure Primary Phase -G UF4-ThF4-LiF 31.2-15-53.8 736 +3 LiFe4u F4-Li Fe4Th F4 (ss) 33-10.57 687 3 LiF+4U F4-LiF°4Th F4 (ss) 33-13.2.53.8 7233 LiF°4UF4-Li F*4Th F4 (ss) 5.26-69 581 12 7LiF+6Th F4-7Li F~6UF4 5:29-66 64513 LiFs2ThF , (ss) 5-31-64 66713 LiF+2Th F4 (ss) 5-33-62 70413 LiF2Th F4 (ss) 5-35-60 7143 LiFe2Th F4 (ss) 6-24-70 55512 7LiF*6Th F4—7LiF-6U F4 (ss) 72667 6125 7LiF+6Th F4--7LiF06UF4 (ss) 8-15-77 54813 LiF + 3LiF+Th F4 (ss) 10-10-80 649 3 LiF 10-15-75 547t 3 3LiF«Th F4 (ss) 10-16.74 55512 3LiFsTh F4 (ss) 10-18-72 54412 3LiF+Th Fgq (ss) + 7LiFe6Th F4-7Li F°6UF4 (ss) 10-20-70 57719 7LiFe6Th F“--7LiF'6UF4 (ss) 10-24.66 596+ 3 7LiF+6Th F4-7LiF-6UF4 (ss) 10-26-64 6003 7LiF6Th F4-7Li F-6UF4 (ss) 10-36.2-53.8 7701 3 LiFedThF ,~LiF+4UF , (ss) 772 £ 2 LiFe4Th F,~LiF-4U Fq (ss) 10.50.40 880 12 LiFe4Th F4-LiF'4U Fa {ss) 107020 101316 UF“-ThF4 (ss) 12-15.73 53313 3LiFTh F4 (ss) 12.5-17.70.5 56513 7LiF*6Th F4—7LiF~6U F4 (ss) 13-12.75 528 3 3LiFeTh Fgq (ss) 15-12.73 52312 LiF + 3LiFsTh F4 (ss) 5283 LiF+3LiF-ThF4 (ss) 151768 587 £ 2 7LiF*6Th F4-7LiF-6U F4 (ss) 16-11-73 519 £2 3LiF~ThF4 (ss) 161272 5283 7LiF+6Th F4-7LiF-6U Fq (ss) 16.2-30-63.8 777 13 LiF+4ThF ,~LiF+4UF ; (ss) 17-11.72 532+2 7LiF~6ThF4-7LiF-6UF4 (ss) + 3LiF'ThF4 (ss) 17-12,5.70.5 547 +3 7LiF+6Th F4-7Li F-tSUF4 (ss) Table 4 (continued) Composition Liquidus (molo %) Tem;;erofure Primary Phase (°C) UF ,~ThF ,-LiF 18-10-72 511 12 3LiF+ThF, (ss) 18-18-64 61214 7LiF+6ThF ,~TLiF-6UF (ss) 18-20-62 634 4 LiFe2ThF (ss)° 18-22-60 680 1 3 LiFedThF ,~LiF*4UF , (ss) 20-8-72 508 +2 3LiFsThF, (ss)° 20-20-60 637 £2 LiFedThF ,—LiF+4UF , (ss) 20-40-40 862 3 LiF+4ThF ,~LiF+4UF , (ss) 20-45-35 892 +2 UF ,~ThF , (ss) 20-60-20 1011 £3 UF ,~ThF , (ss) 21.5-21.5.57 736 12 LiFed4 ThF ,~LiF+4UF , (ss) 35-5-60 630 £ 3 LiFs4UF ,~LiF*d4ThF , (ss) 35-11.2-53.8 72913 LiF*4UF ,~LiF+4ThF (ss) 35-15.50 780 + 3 LiFedUF ,~LiF4ThF, (ss) 39.4.57 625 £2 LiF+4UF ,~LiF+-4ThF (ss) 40-6.2-53.8 717 £3 LiFedUF ~LiF+4ThF (ss) 40-10.50 76714 LiFedUF ,~LiF*4ThF, (ss) 40-20-40 82914 LiF*4UF ,~LiF+d4ThF , (ss) 40-40-20 972+ 3 UF ,-ThF, (ss) 50-10-40 808 * 3 LiFe4UF ,~LiF+4ThF , (ss) 50-30-20 968 * 4 UF ,~ThF , (ss) 60-20-20 960 1 2 UF 4~ThF, (ss) 70-10-20 963 +3 UF ,~ThF,, (ss) %The uncertainty in temperatures in this table indicates the temperature differences between the quenched samples. bSolid solution, “Most of the phases were identified by optical microscopy; in addition, this phase was identified by x-ray dif- fraction. these invariant points are the following: The peritectic at 609°C - LiF-4UF4-LiF-4ThF4 (ss) + liquid == 7LiF.6 ThF ,~7LiF6UF , (ss) + LiF:2ThF , (ss) The peritectic at 500°C 3LiF-ThF, (ss) + liquid == 7LiF.6UF ,~7LiF«6ThF, (ss) + LiF The eutectic at 488°C Liquid = LiF + 3LiF-ThF4 (ss) + + 7LiF-6UF4--7LiF-6ThF4 (ss) The equilibrium phase diagram in Fig. 1 is based on the thermal analysis data shown in Table 3 and the results of quenching studies shown in Table 4 and in the appendix. The re- sults of quenching experiments, excluding liquidus 17 temperature and compositions, which aid in locating the invariant points and in describing the invariant reactions are shown in Table 5. The peritectic or eutectic nature of the invariant reactions is further confirmed by the construction of compatibility triangles and observing the position of these triangles relative to their invariant points. Because this system contains several series of extensive ternary solid solutions, it cannot be completely described without knowledge of the composition of the crystalline phase or phases at equilibrium at any temperature and composition. (The phrase ‘‘ternary solid solution’’ as used in this report implies that the solid solution compo- sition lies within the system LiF-UF,.-ThF . Table 5. Invariant-Point Data? for the System LiF-ThF ,-UF, Quench Composition Temperature? (mole %) ':OC) Phases® Above Temperature Phases® Below Temperature Tl'nF4 UF4 6 22 495 2 Liquid + LiF Liquid+LiF+7LiF-6UF4— 7LiF°6ThF4 (ss) 492 2 Liquid + LiF + 7LiF-6UF ,~ LiF? + 7LiF-6U|':4-7LiF°6T|'|F4 (ss)d 7LiF~6ThF4 (ss) 8 20 502 £ 2 Liquid + 3LiF°ThF4 (ss)d Liquid + 3LiF-T|'|F4 (ss)+ 7LiF-6UF4- 7LiF°6'|'|'|F4 (ss) 498 +2 Liquid-i-:?oLiFoThF4 (ss)+7LiF-6UF4— LiF +3LiFoThF4 (ss)+7LiF°6UF4— 7LiF°6ThF4 (ss) 7LiF+-6ThF , (ss) 10 18 502 +2 Liquid + 3LiF'ThF4 (ss) LiF + 3LiF-ThF4 (ss) + 7LiF-6UF ,~ 7LiF-6'|'|'|F4 (ss) 489 +2 Liquid + 3LiF+ThF , (ss) + 7LiF+6UF ,~ LiF+3LiF-ThF4 (ss) + 7LiF+6UF ,— 7LiF-6ThF4 (ss) 7LiF-6ThF , (ss) 1 16 510 £2 Liquid + 3LiF:ThF (ss) Liquid+3LiF-ThF4 (ss) + 7LiF-6UF ,— 7LiF-6ThF4 (ss) 506 +2 Liquid + 3LiF-ThF, (ss)+7LiF-6UF4- Liquid -*-3LiF-ThF4 (ss) + 7LiF+6UF ,~ 7LiF-6T|'|F4 (ss) 7LiF-6ThF, (ss) + LiF [inclusions in 3LiF-ThF , (ss)] 496 +3 Liquid + 3LiF-T|'1F4 (ss) + 7LiF-6UF4— Liquid + fBLiF-ThF4 (ss) + 7LiF-6UF4— TLiF-6ThF, (ss) + LiF [inclusions in TLiF«6ThF (ss) + LiF 3LiF-ThF, (ss)] 492 +2 Liquid + 3Lii"'-T|-|F4 (ss) + 7LiF-6UF ,— 3LiF°ThF4 (ss) + 7LiF+6UF ,— 7LiF-6ThF4 (ss) + LiF 7LiF°6ThF4 (ss) + LiF 11 17 501 3 Liquid + 7LiF-6UF4-7LiF°6ThF4 (ss)+ Liquid + 7LiF-6Ul"'4—7LiF~6ThF4 (ss) + 3Lil=-Thi"'4 (ss) 3LiF°ThF4 (ss) + LiF 497 13 Liquid + 7LiF-6UF4—7LiF-6ThF4 (ss) + 7Lil'-'°6UF4-7LiF°6ThF4 (ss) + 3LiF-ThF4 (ss) + LiF 3LiF'ThF4 (ss) + LiF 12 15 511 3 Liquid + 3LiF-'l'hF4 (ss) Liquid + 7LiF-6UF4—7LiF-6ThF4 (ss) + 3LiF~ThF4 (ss) 502 £3 Liquid + 7LiF-6U F“—7LiF-6ThF4 (ss) + 7LiF°6UF4—7Li|':-6ThF4 (ss) + 18 3LiF-ThF , (ss) 3LiF"|'|1F4 {(ss) + LiF ;; 1% Table 5 (continued) Quench Composition T b emperature Phases® Above Temperature Phases® Below Temperature (mole %) ©Q) ThF, UF, 12 16 523 £2 Liquid + 7LiF°6UF4--7LiF-6ThF4 (ss) Liquid + 7LiF-6UF ,~7LiF+-6ThF , (ss) + LiF-ThF, (ss) 504 £3 Liquid + JLiF+-6UF ,~7LiF-6ThF , (ss) + JLiF-6UF ,~7LiF-6ThF , (ss) + LiF 3LiF-ThF,, (ss) 1 26.5 490 £ 3 7Li F'6ThF4 {ss) 12 487 £2 TLiF-6ThF 4 (ss) 1 27.5 485 +3 (ss) 1 28 490 £ 3 485+3 TLiF+6UF ,~TLiF-6ThF , (ss) + ALiF-UF , + LiF(?) + liquid(?) Liquid + LiF+4UF ,~LiF+-4ThF , (ss)? 615 + 4 Liquid + LiF-2ThF (ss)? Liquid + LiF-4UF ,~LiF-4ThF, (ss)? 24 18 640 +3 22 20 615 14 Liquid + 4LiF-UF, + 7LiF-6UF4_ Liquid + 4l.iF~UF4 + 7LiF.6UF4_ 4LiF-UF , + 7LiF-6UF4-7LiF-6ThF4 Liquid + 7LiF.6U F4'—-7LiF~6ThF4 (ss) 4LiF-UF4 + 7LiF~6UF4—7LiF'6ThF4 (ss) + LiF 4LiF-UF4 + 7LiF-6UF4--7LiF'6ThF4 (ss) + LiF 4LiF',UF4 + 7LiF°6UF4—7Li F-6ThF4 (ss) + LiF 4LiF-UF , + 7LiF-6UF4-7LiF'6ThF4 (ss) + LiF(?) + liquid(?) 7LiF-6UF4«7LiF-6ThF4 (ss) + 4LiF.UF, + LiF Liquid + LiF-2ThF, (ss)? Liquid + 7LiF+6UF (~7LiF-6ThF , (ss)? Liquid + 7LiF-6UF ;~7LiF+6ThF , (ss)? 2For liquidus data near invariant points see Table 4. bThe uncertainty in temperatures indicates the temperature differences between the quenched samples. ©Only phases found in major quantity are given. Minor quantities of other phases resulting from lack of complete reaction between solids or from trace amounts of oxide impurities are not noted. Glasses or poorly formed crystals assumed to have been produced during rapid cooling of liquid were found in those samples for which the observed phase is indicated as *‘liquid."”’ dMost of the phases were identified by optical microscopy. In addition, this phase was identified by x-ray dif- fraction. Each of the solid solutions in this system, how- ever, may be formed from mixtures of two end members and in this sense form a binary series.) In general, in any series of complete solid solution the physical properties (e.g., density, optical properties, x-ray diffraction patterns, etc.) of the individual members show a continuous change between those of the end members. Hence a determination of refractive indices of a number of samples of known compositions in the solid solution series provides a method of establishing in the ternary system tie lines between the compo- sition of crystals in this solid solution series with the liquid with which it is in equilibrium. In the case of the system LiF-ThF,-UF, the determination of refractive indices of the members of each of the four ternary solid solution series present provides a particularly good method of establishing tie lines, because the refractive indices of the end members of each series are so different that a good degree of precision can be obtained. Once the tie lines are established for a primary- phase areaq, the fractionation paths may be drawn. Fractionation paths in four of the primary-phase areas of system LiF-UF,-ThF, are shown in 19 Fig. 7. The compounds LiF and 4LiF.UF, do not form solid solutions. Consequently, the tie lines, equilibrium paths, and fractionation paths for their primary-phase areas can be drawn directly from Fig. 1, and the case is trivial. The fractionation paths for the UF 4~ ThF (ss) primary- phase area cannot be drawn from Fig. 1. From Fig. 6 it can be seen that the indices of refraction for UF ,-ThF , (ss) do not always change rapidly enough with respect to composition to allow a high degree of precision in tie-line de- terminations. Consequently, no attempt was made to determine the fractionation paths in this primary-phase area. ThF, LiF- 4ThF, LiF-2ThF, =4 7LiF-6ThFq P g THE 20 MOLE % LiF JOIN AND THE LIF°4UF4-LIF°4TI1F4 (ss) FRACTIONATION PATHS A diagram of the 20 mole % LiF join is shown in Fig. 8 and is based on the thermal analysis data in Table 3 and the results of quenching studies in Tables 4, 6, and 7. The join contains the LiF04U|:4--L|'F-4ThF4 (ss) series, whose members are green, are biaxial negative, and have optic angles of approximately 10° The indices of refraction of these solid solutions shown in Fig. 9 and Table 8 vary almest linearly with UF, concentration, UNCLASSIFIED ORNL-LR-DWG 35505R LiF 3 AV UF, VRV % = NV VIRLVIIRY. 7LiF-6UFR, P LiF - QUF, Flg. 7. Fractionation Paths. 20 — e — e - UNCLASSIFIED ORNL-LR-DWG 27915AR o THERMAL BREAKS | | | © QUENCH DATA SEPARATING REGIONS (a@)(4}(c) AND (d) 1100 | THE SYMBOLS BELOW INDICATE CHANGES WITH DECREASING TEMPERATURE o (a) TO {5) © (5 TO (o) e (c) TO (0} e (8) TO (&) (@) - 1000 L\?\ ) T ——— \J\J»\:i g '\JN} 4 w I3 3 () g LIQUID + UF, — ThF, ss g, 900 T = o ~ I|.|ouu)+ UFy~ThF, ss +LiF-4UF, —=LiF -4 ThF, 55 \t‘\i!\: & Z) I3 “ 800 - —— {d) E e, Lif - 4UF, —LiF - 4ThF, ss 700 ) 10 20 30 40 50 60 70 80 UF, (mole %) Fig. 8. The Join LiF-4UF4-LiF'4ThF4. UNCLASSIFIED ORNL-LR-DWG 27916R .62 1.60 g £ 158 = a” y INDEX OF L~ o REFRACTION\S/‘// )/fl = 1.56 ' ; ° o~ INDEX OF i REFRACTION o ,54l e z V/ 1.2 1,50 (o] 10 20 30 40 50 €0 70 80 UF, (mole %) Fig. 9. Indices of Refraction vs Composition for LiF-4UF4—LiF-4TI-|F'4 (ss). The fractionation paths for the LiF-4UF,- LiF-4ThF, (ss) primary-phase area shown in Fig. 7 are based on the tie-line data in Table 7. They tend to parallel the system LiF-ThF, over most of the LiF.4UF ,~LiF.4ThF, (ss) primary- phase area, and they change from this pattern only at the higher UF , concentrations. THE 33)% MOLE % LiF JOIN AND THE LiF-2Th(U)F, (ss) FRACTIONATION PATHS A diagram of the 33, mole % LiF join is shown in Fig. 10 and is based on the thermal analysis data in Table 3 and the results of quenching studies in Tables 4, 9, and 10. The join contains the LiF.2Th(U)F , (ss) series, whose members are green and are uniaxial negative. The indices of refraction of these solid solutions shown in Fig. 11 and Table 11 vary linearly with UF, concen- tration. The maximum extent of LiF2Th(U)F (ss) at the solidus is 23 mole % UF4. The fractionation paths for LiFoZTh(U)F4 (ss) primary-phase area shown in Fig. 7 are based on the tie-line data in Table 10. The fractionation paths tend to parallel the system LiF-ThF, over the entire primary-phase area. THE 53.8 MOLE % LiF JOIN AND THE TLiF<6UF4~7LiF-6ThF , (ss) FRACTIONATION PATHS A diagram of the 53.8 mole % LiF join is shown in Fig. 12 and is based on thermal analysis data in Table 3 and the results of quenching studies in Tables 4, 12, and 13. The join contains the 7LiF-6UF4-7LiF-6ThF4 (ss) series, whose members are green and are uniaxial. Their indices of refraction, shown in Fig. 13 and Table 14, vary linearly with UF, concentration. There should be one composition which is practically isotropic, since the ordinary and extraordinary indices of refraction cross. Actually there is a range of compositions in the midportion of the series which have a birefringence too low to be observed. . : The fractionation paths for the 7LiF-6ThF4- 7LiF~6UF4 primary-phase area shown in Fig. 7 are based on the tie-line data in Table 13. They parallel the system LiF-ThF, over most of the 7LiF-6UF4-—7LiF-6ThF4 primary-phase area and change from this pattern only at the higher UF4 concentrations. THE 75 MOLE % LIiF JOIN AND THE 3LiIF UF4 ThF4 (*C) N, (mole % UF4) 2 29 586-591 1.508 5.5 4 27 558-592 1.510 7 5 24 558-563 1.510 7 5 29 557-605 1.512 9 5 31 599 1.512 9 5 33 584-599 1.512 9 5 35 601 1.512 9 6 24 553 1.512 9 7 26 550607 1,510 7 10 20 546-568 1.516 12.5 10 24 576-593 1.516 12,5 10 26 597 1.515 12 12.5 17 536-562 1.524 19.5 13 30 578-610 1.518 14.5 15 17 585 1.520 16 15 25 532-606 1.519 15 . 15 28 578-610 1.520 16 16 12 525 1.524 19.5 17 12.5 521-547 1.525 20.5 . 17 26 578-610 1,522 18 18 18 554-608 1.520 16 18 20 601-612 1.522 18 554-608 1.522 18 18 22 521 1.524 19.5 607 1.522 18 608 1.522 18 18 24 532-612 1.522 18 20 20 520-620 1.526 21.5 20 22 612 1.524 19.5 532 1.526 21.5 21.5 21.5 596-607 1.526 21.5 25 15 528-609 1.532 26.5 601 1.534 28.5 510-612 1.532 26.5 26.5 2 497 1.548 41 27 2 493 1.550 42.5 28 1 497 1.550 42.5 28 10 608 1.534 28.5 544 1.536 30 30 10 609 1.536 30 ’ 528 1.538 32 33 10 596-601 1.540 34 . 35 5 528-604 1.544 37.5 606 1.544 37.5 510 1.546 39 39 4 553-609 1.547 40 30 Table 14. Optical Properties for 7LiF-6UF ,~7LIF-6ThF, (ss) Index of UF4 Content Refraction, Birefringence (mole %) N w 10 1.514 0.003 16.2 1.522 Low 23.1 1.528 Very low 1.529 Very low 1.530 Very low 3]02 10538 Very low 36.2 1.540 Low 1.542 Low UNCLASSIFIED ORNL-LR-DWG 27918R2 1.62 » 160 S o Q 1.58 < - @ N, =ORDINARY INDEX OF REFRACTION v N, =EXTRAORDINARY INDEX OF REFRACTION\\ T 456 w - 5 P > W 1.54 = ’-,-/ - —-’//f’ 1/ 1.50 &= ] 5 10 {5 20 25 30 35 40 45 UF4 (mole o/o) Fig. 13. Indices of Refraction vs Composition for 7|..iF-6ThF4—7LiF~6UI"'4 (ss). studies in Tables 4, 15, and 16. The join con- tains the 3LiF:ThF, (ss) series, whose members are green, biaxial negative, and have optic angles of approximately 10° The indices of refraction of these solid solutions shown in Fig. 15 and Table 17 vary linearly with UF, concentration. The maximum extent of 3LiF-Th(U)F4 (ss) is 15.5 mole % UF . The fractionation paths for 3LiF-Th(U)F4 (ss) primary-phase area shown in Fig. 7 are based on the tie-line data in Table 16. RELATIONS BETWEEN THE SOLID SOLUTIONS Compatibility Triangles Since the composition of each of the phases in equilibrium at each of the invariant points has been determined, this information can be used to construct the compatibility triangles associated with the invariant points. Figure 16 shows these triangles and is based on the tie-line data in Table 18. The position of the invariant-point compositions relative to their compatibility triangles indicates that the invariant points at 609, 500, and 488°C are peritectic, peritectic, and eutectic, re- spectively. These conclusions are in agreement with those in the section ‘‘General Discussion of the System LiF-UF ,-ThF, and the Limiting Binary Systems,’’ this report. The direction of decreasing temperature along the boundary line between the primary-phase areas of 7LiF-6Ul":4—7LiF-6ThF4 (ss) and LiF.4UF - LiF-tlThF4 (ss) is difficult to determine because the temperature variation along this boundary line is less than 5°C. The relative directions of the tie lines from the 609°C invariant point to the corners of the associated compatibility triangle (Fig. 16) indicate, however, that this boundary temperature decreases in the direction of the ternary invariant composition, Subsolidus TwoePhase Regions For a point representing a specified composition in any two-phase subsolidus region in the system LiF-UF -ThF ,, the tie line connecting the compo- sitions of the two phases in equilibrium at that point must be a straight line passing through the point, This fact provides a method for checking the accuracy of the refractive index curves (Figs. 8, 11, 13, and 15) of the ternary solid solutions, Tie-line data are given in Table 19 for the following regions: LiF + 3LiF-Th(U)F, (ss) LiF + 7LiF6ThF ,—7LiF-6UF , (ss) 3LiF-Th(U)F, (ss) + 7LiF-6ThF ,~7LiF -6UF, (ss) The ends of these tie lines and the corresponding points of nominal composition are shown (Fig. 17) to be nearly colinear. 31 32 TEMPERATURE (°C) 575 550 525 500 475 450 (a) (6) (c) {(d) (e) () UNCLASSIFIED ORNL-LR-DWG 35503R LIQUID + 3LiF - ThF, ss LiF + LIQUID LiF + 3LiF - ThF, ss +LIQUID LiF + 7LiF - 6 ThE, — 7LiF - 6UF, ss + LIQUID 4LiF-UF, + LIQUID + LiF 4LiF-UF, + LIQUID (g) 4LiF-UR + 7LiF-6ThF, ~7LiF -6UF, ss + LIQUID (A) 3LiF-ThF, ss (/) 3LiF - ThF, ss + 7LiF - 6ThF, — 7LiF - 6 UF; ss + LiF (/) LiF + 7LiF - 6 ThF,— 7LiF - 6 UF, ss (k) LiF + 4LiF +UF, + 7LiF -6 ThF, — 7LiF - 6 UF, ss (/) 4LiF-UF,+ 7LiF-6ThF,— 7LiF - 6 UF, ss o A THERMAL DATA ® QUENCH DATA O TIE LINE DATA LIQUID (2) ‘-‘-.___J___—_————_? NG (e) ¢ @ T (4) () () Lo [~ / IR \ !\(/) 10 15 20 25 UF, (mole %) Fig. 14. The 75 Mole % LiF Section, (U Table 15. Thermal-Gradient Quenching Data for the 75 Mole % LiF Join? U F4 Content Temperofureb (molo %) °c) Phases® Above Temperature Phases® Below Temperature 2 5544 Liquid + 3LiFsThF , (ss) 3LiFThF , (ss) 5 533 +3 Liquid + 3LiF*ThF , (ss) 3LiFThF , (ss) 460 + 29 3LiFeThF (ss)° LiFeThF ,° + 7Li F6UF ,~ 7LiF6ThF, (ss)? 10 51510 Liquid + 3LiFTh F4 (ss) 3LiF°ThF4 (ss) 49315 3LiF+ThF, (ss)€ 3LiF+ThF, (ss)€ + LiF + 7LiF+6UF 4~ TLiF6ThF, (ss) 13 506 * 3 Liquid + 3LiFsThF (ss) 3LiFeThF , (ss) 49113 3LiF*ThF, (ss)f 3LiF+ThF, (ss)® + LiF + 7LiF6UF ;~7LiF*6ThF, (ss) 15 5003 Liquid (traces) + LiF (traces) + LiF + 3LiF*Th F4 (ss)+ 7Li F'6UF4-— 3LiF6ThF, (ss)? 7LiF*6ThF (ss) 480 +2 LiF + 3LiF-ThF , (ss)€+ 7LiF«6UF,— LiF + 7LiFs6UF ;~7LiF*6ThF, (ss)® TLiF6ThF, (ss)€ 20 5035 Liquid + LiF Liquid + LiF + 7LiF6UF .~ 7LiF*6ThF, (ss)€ 491 %2 Liquid + LiF + 7LiF-6UF ,~ LiF + 7LiF*6UF ,~7LiF*6 ThF, (s5)° 7LiF<6Th F4 (ss) 4506 Table 4 for liquidus values. The uncertainty in temperatures indicates the temperature differences between the quenched samples. cOnly phases found in major quantity are given. Minor quantities of other phases resulting from lack of complete reaction between solids or from trace amounts of oxide impurities are not noted. Glasses or poorly formed crystals assumed to have been produced during rapid cooling of liquid were found in those samples &r which the observed phase is indicated as *‘liquid."’ This exsolution was observed by using xeray diffraction technique only. ®Most of the phases were identified by optical microscopy; this phase was also identified by x-ray diffraction, 33 Table 16. Tie-Line Data for 3LIF-ThF, (ss) Primary-Phase Area Quench Composition Temperature Index of Solid Solution (mole %) Range Refraction, Composition UF, T, (°C) N., (mole % UF ) 2 24 559 1.490 2.0 5 19 560 1.490 2 10 16 535 1.496 6.5 12 15 530 1.495 6.0 15 12 514-.525 1.500 10.0 16 1n 513 1.500 10.0 18 10 504-510 1.500 10.0 20 8 504 1.503 12.5 UNCLASSIFIED ORNL-LR-DWG 31217R2 1.540 £ 1.530 — e | P4 2 1.520 MAXIMUM EXTENT OF — = o 3LiFThF, = SOLID SOLUTION @ : j W 1.510 T 4.6 L 4 g 1.500 FRQCT\O Y \ ) w _——_-'_'—-‘"_'——-L'-f_ 2 <) UF, CONTENT {mole %) Fig. 15. Indices of Refraction vs Composition for 3LIF°TI1F4 (ss). Isothermal Sections The equilibrium-phase behavior of a ternary system involving solid solutions can be clearly and unambiguously described only by an extensive series of isothermal sections, An abbreviated series of such sections for the system LiF-UF - ThF , is presented in Figs. 18 through 21. These 34 Table 17. Refractive Indices for 3LiF-ThF, (ss) UF4 Content Refractive Indices (mole %) N, N'y 2 1.482 1.490 S 1.486 1.494 10 1.492 1.498 13 1.496 1.503 15 1.498 1.507 show the polyphase equilibria for all compositions at the temperatures specified. ACKNOWLEDGMENTS It is a pleasure to acknowledge the assistance of T. N. McVay, who was responsible for all the refractive index measurements in the system UF ,-ThF, and a portion of the petrographic phase identification in the system LiF-UF,-ThF,. In addition we are especially grateful to R, F. Newton, F. F. Blankenship, and J. E. Ricci for helpful advice concerning many phases of the investigation. 'y {e 1Y [ 3 UNCLASSIFIED ORNL-LR~-DWG 35504 ThF, LiF - 2ThF, 7LiF - 6ThF, ~—609°C 3LiF - ThF4 (c) LiF 4LiF - UF,, 7LIF - 6UF, LiF - 4UF, UF, Fig. 16. Compatibility Triangles in the System LiF-UF4-ThF4. 35 Table 18. Compatibility Triangle Data Quench Composition Phases Present* Refractive Indices of Solid Solution Composition (mole %) of Solid Solution (mole % UF)) UF, ThF, Ne N., T4 27 1 7LiFo6UF4—7LiFo6ThF4 (ss) 1.550 42,5 4LiF-UF4 LiF 28 1 7Lti6UF4-—7LiF-6ThF4 (ss) 1.550 42.5 4LiF-UF4 LiF 26,5 1 7LiF-6UF4--7LiF-6ThF4 (ss) 1.550 42,5 4LiF-UF‘4 LiF 27 2 7LiF‘6Ul':4—7LiF-6TI'|F4 (ss) 1.550 42,5 4LiF-UF4 LiF 15 10 7LiFo6UF4--7Li!’-6Thl’=4 (ss)** 1.538 1.506 32 Z!Lil"'-'l'hF4 (ss)** 1.506 15 LiF 17 LA 7LiF-6UF4—7LiF~6ThF4 (ss) 1.536 30 3LiF-ThF4 (ss) 1.504 13.5 LiF 20 8 7LiF06UF4—7LiF-6ThF4 (ss)** 1.537 31 3LiF-T|'|F4 (ss)** 1.504 13.5 LiF 18 10 7LiF‘6UF4-7LiF-6ThF4 (ss) 1.536 30 3LiF-ThF4 (ss) 1.504 13.5 LiF 18 22 LiF-4UF4-LiF-4ThF4 (ss) 1.558 28 LiF-2ThF4 (ss)** 1.564 23 7LiF-6UF4-7LiF-6ThF4 (ss)** 1.524 23 *Only phases found in major quantity are given. Minor quantities of other phases resulting from lack of complete reaction between solids or from trace amounts of oxide impurities are not noted. Glasses or poorly formed crystals assumed to have been produced during rapid cooling of liquid were found in those samples for which the observed phase is indicated as **liquid.”’ **Most of the phases were identified by optical microscopy; this phase was also identified by x-ray diffraction. 36 [ Taoble 19, Subsolidus Two-Phase Reglons Quench . . Com‘:’os‘:fion Refruct.we Indl.ces Composition Phases Present* of Solid Solution of Solid Solution {mole %) N N (mole % UF4) UF, ThF, Y @ 4 19 LiF :‘SLiF-ThF4 (ss)** 1.493 4 5 15 LiF 3LiF-ThF4 (ss)** 1.495 6.5 8 15 LiF 3LiF-ThF4 {ss)** 1.498 9 10 10 LiF 7LiF-6UF4,-7LiF-6ThF4 (ss)** 1.528 22 15 10 LiF 7LiF°6U|"'4—7Li|=°6T|'\|:4 (ss) 1.524 28 20 5 LiF** 7LiF.:6UF ,~7LiF-6ThF, (ss)** 1.542 36 22 6 LiF=** 7LiFo6UF4—7LiF'6ThF4 {ss)** 1.542 35.5 24 4 LiF** 7LiF°6UF4—7LiF-6ThF4 (ss)** 1.546 39.5 25 3 LiF 7LiF-6UF4—7LiF-6ThF4 (ss) 1.548 41 26.5 2 LiF 7LiF-6UF4-7LiF-6ThF4 (ss) 1,548 41 4 27 3LiFoThF4 (ss)** 1.490 2 7LiF-6UF4--7LiF-6ThF4 (ss)** 1.510 7 5 24 3LiF°ThF4 (ss) 1.492 3 7LiF-6UF4--7LiF-6ThF4 (ss) 1.512 9 5 29 3LiFoThF4 (ss) 1.490 2 7LiF-6UF4.-7LiF-6ThF4 (ss) 1.512 9 10 16 :*!LiF-ThF4 (ss) 1.498 8 7LiF-6UF4--7LiF-6Th|"'4 {(ss) 1.528 23.5 é 24 I*!LiF-ThF4 (ss) 1.494 5 7LiF-6UF4—7LiF'6ThF4 (ss) 1.514 10 10 18 3Li|="l'h|=4 (ss) 1,498 8 7LiF-6UF4—7LiF-6ThF4 (ss) 1.526 21.5 10 20 3LiF-ThF4 {ss) 1.496 6.5 7LiF'6UF4—7LiF-6ThF4 (ss) 1.522 18 12 15 3LiF-ThF4 (ss) 1.500 10 7LiF-6UF4—7LiF-6ThF4 {ss) 1.530 25 12.5 17 3LiF.ThF4 (ss) 1.496 6.5 7LiF~6UF4--7LiF-6ThF4 (ss) 1.528 23,5 17 12.5 3LiF-ThF4 (ss) 1.504 13 7LiF-6UF4—7LiF'é'l'hl"'4 {ss) 1.532 26.5 *Only phases found in major quontity are given. Minor quantities of other phases resulting from lack of complete reaction between solids or from trace amounts of oxide impurities are not noted. Glasses or pocrly formed crystals assumed to have been produced during rapid cooling of liquid were found in those samples for which the observed phose is indicoted as ““liquid.”’ **Most of the phases were identified by optical microscopy; this phase was also identified by x-ray diffraction. 38 UNCLASSIFIED ORNL—LR—DWG 35740R 3 50% ThF, 7LiF-6ThF, ® PHASE COMPOSITION A QUENCH COMPOSITION 3LiF - ThF, -— -— —— e - - - - — —— =3 —— - — UF, 7 LiF - UF, Fig. 17. Subsolidus Tle Lines. 1) Q) » UNCLASSIFIED ORNL—LR—DWG 35742 4 (@) CONTAINS: 1) LiF-4 ThFy— LiF-4UFfF,ss 2) LiF-2ThF,ss 3) 7LiF- 6 ThF, — 7 LiF-6UF,ss 4) LIQuUID LiF - 4ThF4 — —) 'y . . %o, LiF -2ThE », e q 5 . < o <. e < [ ] “ 9\ . v .o ® x < .. P/\ /d\ e A ‘(} ® 'é(\ fa)l o. 'éf\ > * P\P\G (’,&\ LS c’“ .o <. _‘\’ . p‘%‘ P /4}9% N ¢ A g 7 e » 66)( Za “ 77 % %\ /c) P% ..// .. % r 7 e V4 o. /7 2oy % Y4 ¢ ° / 7 r-} <, . Ay ,/ // < > * /7 e 3 ‘ /7 A= . / A %P\ % /// ® S?\ . [} /I/ "\.o P “ .. x = .. <. © [ A A% . LIQUID C s Tx% & s % / AN C'“ 4 . Lif < o - . N P‘p N\ 0. ‘5&‘ .. » ° . LIQUID < '. Lif \/ \ \/ VALV V \V4 LV UF, 7LiF-6UF4 LiF-4UF4 Fig. 18. 609°C Isothermal Section. 39 UNCLASSIFIED ORNL—LR—DWG 35744 TLiF +6ThFq g < (@) CONTAINS: " s 1) 7LiF- 6UF, — 7LiF- 6 ThF,ss ° % 2) 3LiF- Thi,ss -.’\A 3) LiF ® °, “a 4) LIQUID .o '0" e o (b) CONTAINS: ® “ 'x 1) TLIF- 6UF, ~7LiF-6ThF, ss % <. 2) LiF- 4UFy ~LiF-4ThF,ss . ‘5@ 3) LiF-2 ThF,ss e A 0. 5‘\ .. ?% , 3LiF-ThFss + '..(b),/ SLIF-ThGy A 7LiF- 6UF, —TLiF- 6UF, ss " o. ° (’2\ [ ‘. - ® . % < ® .o "\ .. .. ‘? .. ”/¢. 6‘/; . ”’ -~ [} LiIF + ‘. e % o [ ] o [ 3LiF- ThF, ss . P o % . 4” // ¢ . PR ® - (@) PR % p(, - _ e -~ - LIQUID + “ % P O\ TLiF- 6UF, — o =7 =="" LiF+LIQUID ¢\ 7LiF-6ThFyss 2 - - 7LiF- 6UF, Fig. 19. 500°C Isothermal Section. « UNCLASSIFIED ORNL—LR—DWG 35738 ThE, 73 (o) CONTAINS: . 1) TLiF- 6UF, — 7LiF: 6 ThF,ss * & : ‘ AN 3) LiF e <. 4) LIQUID e ® 0 ‘.. %) (b) CONTAINS: <\ * ® o 1) 7LiF-6UF, —7LiF-6ThF, ss [ . %4\ 2) LiF - 4UF, —LiF- 4 ThF, ss [ '.. /%“ 3) LiF- 2ThF, ss ¢ v 3LiF-ThR, ss + o % 7LiF- 6UF, —7 LiF- 6ThF, ss % (5) o 1IN : v 3LIF -ThR, 4 ./A . s <. . o < [ ] .’. .o 6&’(\ [ ] e ;" e \ L] b - : . o C. LiF + ° =% = . ™ e o — L ashas™ SLIF-ThRyss % =TT N s~ - % % i P *®y // 3LiF- ThF,s55 + - o ¥ 7 4 . e X o7 TLIF-6UF, — _ - % ,7 TLiF -6 ThEF, s5 LiF + = -’ .= e C 7T HLF T TLiF-B8UR, — 7LiF-6ThF, ss . ;\\ P - * < - - e 1 ///,/’// —————— — ::_.:_-:.—:-". ¥ //’/ ——————————— -— "'"'-.-.---- .. 6’(\ ,/ —————————— - - - > Lip &2l o= = = TN V@) e \/ \/ \/ VAP 4 Lif - UF, Fig. 20. 488°C Isothermal Section. 41 UNCLASSIFIED ORNL—LR—DWG 35739 ThF, (o) CONTAINS: 1) LiF- 4UF, —LiF - 4ThF, ss 2) 7 LiF-BUF, — 7TLiF- 6 ThF, ss 3) LiF- 2 ThF, LiF - 4 ThE, #— FraThg A (5) CONTAINS: <. % 1) 7LiF- 6UF, ~ 7 LiF+ 6 ThF, ss <\ o . ‘> % 2) 3L1F‘ThF455 X %\0. 3) LiF LiF-2Thf RN A R N E) o 3 % >\ (c) CONTAINS: . [} A S %% %G 1) 3LiF-ThF,ss . o % 6‘\0 ] . 4 A ‘(\ /\.. > .. d:p 2) LlF C ok S e X ST % 7% 23 = @A?\m .o /,// .° . 7 LiF -6ThE, X / 2 9 Py ’;“ 0// / .. 64\ o.. I /(a)// x (o. )?\ / A ° .. / // <. “ .. (’K\ " 7 DA =, / 3LiF- ThF, ss® ‘1, % % _ 4% e ’, =\ e P +7LiF-6UFR=% 4 VS o 3LIF-ThE ¢ 7LIF-6ThFgss _:./’ C ol .o _________ Pl ) C} .o {cypr L ° ‘5’/\ < ® / ’ .. ‘5Pd‘ ¢ )y -7 . 7% // /// .. '{‘p .O 7/ i L . / P LiF + i * Y -7 TLiF-6UF, —7LiF-6ThFss ¢ . e ° . /7 7 0. [ -~ ® LiF &~ AV vV \V, VARV V V */ \Y/ UF, 7 LiF - BUF, LiF -4UF, 42 Fig. 21. 450°C Isothermal Section. » [ Appendix MISCELLANEOUS THERMAL-GRADIENT QUENCHING RESULTS FOR THE SYSTEM LiF-UF-ThF, Composition 7LiF-6T|1F4 (ss) Temperature? (mole %) ©c) Phases® Above Temperature Phases® Below Temperature UF, ThF4 2 24 522 + 4 Liquid + 3LiF- ThF4 (ss) Liquid + 3LiF-ThF4 (ss) + 7LiF°6UF4— 7LiF'6ThF4 (ss) 2 29 563 £3 Liquid + 7LiF'6UF4—7LiF*6T|‘|F4 (ss) Liquid + 7LiF-6UF4-—7LiF°6ThF4 (ss) + 3LiF-Th|"'4 (ss) 3 19 561 3 Liquid + LiF Liquid + LiF + 3LiF-T|'|F4 (ss) 4 19 53217 Liquid + LiF + 3LiF°ThF4 (ss) LiF + 7LiF°6UF4—7Li|':-6ThF4 (ss)¢ 4 27 555 4 Liquid + 7LiF-¢$UF4—7LiF°6ThF4 (ss) LiF + 3LiF~ThF4 (ss) + 7LiF°6UF4- 7LiF-6'|'h|"'4 (ss) 548 +4 Liquid + 7Lil=-6UF=4—7LiF-6T|'|F4 (ss) + 7LiF~6UF4-7LiF-6ThF4 (ss) + 3LiF°T|1F4 (ss) 3LiF'ThF4 (ss) 5 15 556 4 Liquid + LiF Liquid+LiF+3LiF-ThF4 (ss) 540 £3 Lic;uid+LiF+3LiF°ThF4 (ss) LiF+3LiF°ThF4 (ss)€ 462 +3 LiF + 3LiF'T|'\F4 (ss) LiF + 3LiF°ThF4 (ss) + 7LiF°6UF4- 7LiF°6ThF4 (ss) 5 19 558 +2 Liquid + 3LiF-ThF4 (ss) Liquid + 3LiF-ThF4 (ss) + LiF 5 24 555 +3 Liquid + 7LiF°6UF4--7LiF-6ThF4 (ss) Liquid + 3LiF-ThF4 (ss) + 7LiF°6UF4— 7LiF-6ThF4 (ss) 549 +3 Liquid + 3LiF-T|'|F4 (ss) + 7LiF-6UF4- 7LiF'6UF4-7LiF-6ThF4 (ss) + 7Li|='6ThF4 {ss) 3LiF°T|1F4 (ss) 5 26 558 +2 Liquid + 7LiF°6UF4—7LiF~6ThF4 (ss) Liquid + 3LiF°ThF4 (ss) + 7LiF'6UF4- 7LiF-6ThF4 (ss) 546 +2 Liquid + 7LiF'6UF4--7LiF-6ThF4 (ss) + 7LiF-6UF4—7LiF'6ThF4 (ss) + 3Lif"'-ThF4 (ss) 3LiF-'I'|'|F4 (ss) 5 29 615 t3 Liquid + LiF°2ThF4 (ss) Liquid + LiF'2ThF4 (ss) + 7LiF+-6UF ,— 7LiF-6ThF4 (ss) 605 +3 Liquid + LiF-2ThF4 (ss) + 7LiF+6UF ,— Liquid + 7LiF'6UF4--7LiF-6ThF4 (ss) 7LiF-6ThF4 (ss) 557 £3 Liquid + 7LiF°6UF4-—7LiF-6ThF4 (ss) Liquid + 7Li|"'°6UF4—7LiF-6ThF4 (ss) + 3Li|"'°'|'hF4 (ss) 547 £ 3 Liquid + 7LiF-6U F4-7LiF-6ThF4 (ss) + 7LiF°6UF4—7LiF-6ThF4 (ss) + 3LiF-ThF4 (ss) 3LiF-ThF4 (ss) 5 31 609 4 Liquid + LiF'2ThI'-'4 (ss) Liquid + LiF+2ThF , (ss) + 7LiF-6UF4- 7LiF'6ThF4 (ss) 602 +3 Liquid + LiF'ZThF4 (ss) + 7LiF+6UF ,— Liquid + 7LiF«6U F4—7Lil'-'-6'|'hF4 (ss) 43 Appendix (continued) Composition Temperature® (mole %) (°C) Phasesb Above Temperature Phasesb Below Temperature UF, ThF4 5 33 605 £3 Liquid + LiF+2ThF ; (ss) Liquid + LiF-2ThF4 (ss) + 7LiF'6UF4-— 7Lil""6Tl'||"'4 (ss) 599 +3 Liquid + LiF-2ThF4 (ss) + 7LiF°6UF4— Liquid + 7LiF-6UF4--7LiF-6ThF4 (ss) 7Li|:°6'|'h!'-'4 (ss) S 35 605 +4 Liquid + LiF-IZThF4 {ss) Liquid + 7LiF'6UF4—7LiF°6'|'hF4 (ss) 6 24 551 £3 Liquid + 7LiF-6UF4—7LiF-6ThF4 (ss) Liquid + 3LiF:ThF , (ss) + 7LiF-6U F4— 7LiF°6ThF4 (ss) 541 3 Liquid+3LiF-ThF4 (ss) + 7LiF+6UF ,~ 3LiF-ThF4 (ss) + 7LiF-6UF - 7LiF-6ThF4 (ss) 7LiF-6ThF4 (ss) 7 26 547 3 Liquid + 7LiF-6UF4-7LiF°6ThF4 (ss) Liquid + 3LiF'ThF4 (ss) + 7LiF-6UF4- 7LiF'6ThF4 (ss) 8 15 517 £3 Liquid-i-LiF=1-3Li|:~'l'hl'-'4 (ss) LiF+3LiF-ThF4 (ss) 480 2 LiF + 3LiF-ThF4 (ss)€ LiF + 3LiF-ThF4 (ss) + 7LiF+6UF ,~— 7LiF-6ThF4 (ss) 10 10 528 =3 LiF + liquid Liquid-&-Li[""+3Li|"'-'l'hF4 (ss) 488 +3 Liquid + LiF +3LiF-ThF4 (ss) 7LiF°6UF4---7LiF-6T|'\F4 (ss)€ + LiFS + 3LiF-'|'|'\F4 (ss)© 464 £3 LiF€ + 3LiF-ThF, (ss) + 7LiF+-6UF ,— LiF€ + 7LiF-6UF ,~7LiF-6ThF (ss)® 7LiF~6T|'|F4 (ss)€ 10 16 533 2 Liquid + 3LiF-T|'|F4 (ss) Liquid + ?»LiF-ThF4 (ss) + 7LiF°6UF4—- 7LiF-6ThF4 (ss) 10 18 5132 Liquid + 3LiF-ThF , (ss) + 7LiF-6UF4— 7LiF'6UF4—7LiF-6ThF4 (ss) + 7LiF-6ThF4 (ss) 3LiF-ThF4 (ss) 10 20 543 +3 Liquid + 7LiF'6UF4—7LiF‘6ThF4 (ss) Liquid + 3LiF°ThF4 (ss) + 7LiF-6UF ,~ 7|..iF°6ThF4 (ss) 538 £ 2 Liquid + 7LiF°6UF4—7LiF-6ThF4 (ss) + 7LiF°6UF4—7LiF~6ThF4 (ss) + f.*lLiF-ThF4 (ss) 3LiF-ThF4 (ss) 10 70 889 4 Liquid + UI""‘—ThF4 (ss) LiF°4UF4—LiF'4ThF4 (ss) 11 32 612 3 Liquid + LiF'2T|'\F4 (ss)® Liquid+LiF°2ThF4 (ss)c+7LiF-6UF4— 7LiF°6ThF’4 (ss)® 607 £3 Liquid + LiF°2ThF4 (ss) + 7LiF+-6UF ,~ Liquid + 7LiF-6UF4—7LiF'6ThF4 (ss) 7LiF‘6ThF4 (ss) 12 15 525 2 Liquid + 3Li|:"°'|'|'\|:4 {ss) Liquid + 3LiF°ThF4 {ss) + 7LiF°6UF4- 7LiF-6ThF4 (ss) 505 £2 Liquid + 7Li|=°6UF4-7LiF-6T|1F4 (ss) + 7LiF-6UF4-7LiF-6ThF4 (ss) + 3LiF-ThF , (ss) 3LiF-ThF , (ss) 12.5 17 532 +4 Liquid + 7LiF'6UF4-7LiF-6ThF4 (ss) Liquid + 3LiF-ThF, (ss) + 7LiF-6UF ,- 44 7LiF~6'|'hF4 (ss) (13 Appendix (continued) Composition Temperature? (mole %) (°C) Phases? Above Temperature Phases? Below Temperature UF4 ThF, 12.5 17 514 3 Liquid + 7LiF<6U F4-7LiF~6ThF4 (ss) + 7Lii:-6UF4-7LiF'6T|'|F4 (ss) + 3LiF-ThF4 (ss) 3LiF-ThF4 (ss) 13 30 688 +2 Liquid + LiF-4UF ,~LiF-4ThF (ss)€ Liquid + LiF-2ThF (ss)© 612 £3 Liquid + LiF'2ThF4 (ss)€ Liquid + 7LiF-6UF4—-7LiF-6ThF4 (ss)€ 15 12 511 £3 Liquid-}-3LiF'ThF4 (ss) Liquid+3LiF°ThF4 (ss)+7LiF~6UF4— 7LiF-6ThF4 (ss) 15 25 612 4 Liquid + Lil:-2ThF4 (ss) Liquid + 7LiF°6UF4—7LiF-6ThF4 (ss) 529 +4 Liquid + 7LiF-6UF4—7LiF-6ThF4 (ss) Liquid + 3LiF-T|'\F4 (ss) + 7LiF°6UF4— 7LiF-6ThF4 (ss) 15 28 680 +3 Liquid + LiF°4UF4—LiF-4ThF4 (ss) Liquid + LiF-2ThF4 (ss) 617 £3 Liquid + LiF-2ThF4 (ss) Liquid + LiF~2ThF4 (ss) + 7LiF'6UF4— 7Lil"'~6ThF4 (ss) 612 +3 Liquid + LiF-2ThF4 (ss) + 7LiF-6UF4- Liquid + 7LiF°6UF4—7Lil"'-6'l'hl=4 (ss)€ 7LiF-6ThF4 (ss) 16 11 510 £2 Liquid + 3LiF-ThF , (ss) Liquid + 3Lil"'°"|"hF4 (ss) + 7LiF'6UF4— 7LiF-6ThF4 (ss) 501 t8 Liquid + 3Lil".ThF4 (ss) + 7LiF°6UF4— Liquid + 3LiF-T|'|F‘1 (ss) + 7LiF°6UF4— 7LiF°6'l'hF4 (ss) 7LiF-6ThF4 (ss) + LiF 492 +2 Liquid + 3LiF"ThF4 (ss) + JLiF-6UF ,— 3LiF-ThF4 (ss) + 7LiF-6UF ;- 7LiF°t€"|"hF'4 (ss) + LiF 7LiF°6ThF4 (ss) + LiF 16 12 523 £2 Liquid + 7LiF°6UF4-7LiF°6ThF4 (ss) Liquid + 3LiF°ThF4 (ss) + 7LiF'6UF4— 7LiF°6ThF4 (ss) 17 11 499 5 Liquid-i-7LiF~6UF4—7LiF-6ThF4 (ss)+ LiF +3Lil='T|'||':4 (ss)+7LiF-6UF4— 3LiF"l'hF4 (ss) 7LiF°6ThF4 (ss) 17 12.5 519 3 Liquid + 7Lii"'-6UF4—7LiF°6ThF4 (ss) Liquid + :?«LiF-ThF4 (ss) + 7LiF°6UF4-— 7LiF’6ThF4 (ss) 507 +3 Liquid + 7LiF-6UF4-7LiF°6ThF4 (ss) + 7LiF-6U|"'4—7Lil'-'-6'|'hF4 (ss) + 3Li|:-ThF4 (ss) 3LiF-ThF4 (ss) 490 +3 7LiF-6U F4—7LiF-6ThF4 (ss) + 3LiF+ThF, (ss) + 7LiF-6UF ,~ 3LiF-ThF‘1 (ss) 7LiF°6ThF4 (ss) + LiF 17 26 660 £3 Liquid + Lil'=-4UF4—LiF-4T|1F4 (ss) Liquid + LiF'2'l'hF4 (ss)€ 617 =3 Liquid + LiF:2ThF, (ss) Liquid + LiF°2ThI'-"4 (ss)€ + TLiF+6UF ,~7LiF-6ThF (ss)° 612 4 Liquid + LiF'2ThF4 (ss) + Liquid + 7LiF-6UF4--7LiF-6ThF4 (ss) 7LiF'6U|"'4—7LiF°6ThF4 (ss)¢ 18 10 502 2 Liquid + 3LiF:ThF , (ss) Liquid + 3LiF°ThF4 (ss) + 7LiF°6UF4- 7LiF'6ThF4 (ss)€ 45 Appendix (continued) Composition Temperature? (mole %) (°C) Phases? Above Temperature Phases? Below Temperature UF4 ThF4 18 10 489 2 Liquid + 3LiF'-ThF4 (ss) + 7LiF°6UF4— 7LiF-6UF4-7LiF-6ThF4 (ss) + 7LiF-6T|'1F4 (ss) 3LiF-TI1F4 (ss) + LiF 18 20 637 13 Liquid + LiF-4UF4—LiF-4ThF4 (ss)€ Liquid + LiF-2ThF‘1 (ss) 615 +4 Liquid + LiF-2ThF4 (ss)® Liquid + 7LiF~6U|:4~-7LiF-6ThF4 (ss) 612 4 Liquid + LiF-2ThF4 (ss) Liquid + 7LiF-6UF4—7LiF-6ThF4 (ss) 18 22 634 4 Liquid + LiF°4U|':4-LiF-llThF4 (ss) Liquid + Lil"'-2T|'|l'-'4 (ss) 626 £3 Liquid + LiF-4UF4-LiF°4ThF4 (ss) Liquid + LiF-2ThF"4 (ss)© 612 £3 Liquid + LiF-2ThF (ss)® Liquid + 7LiF+6UF ,~7LiF-6ThF, (ss)® 612 +4 Liquid + LiF-2ThF , (ss)© Liquid + 7LiF<6UF ,~7LiF+6ThF (ss)€ 20 8 502 +2 Liquid + 3LiF-ThF4 (ss) Liquid + 3LiF-ThF4 (ss) + 7LiF+-6UF ,— 7LiF~6ThF4 (ss) 498 +2 Liquid + 3LiF-ThF4 (ss) + 7LiF-6UF4- LiF + 3LiF.ThF , (ss) + 7LiF-6UF ,~ 7LiF-6ThF4 (ss) 7LiF-6ThF4 (ss) e 20 20 620 £3 Liquid + LiF'4UF4—LiF-4ThF4 (ss) Liquid + 7LiF-6UF4--7LiF°6T|'|F4 (ss)® 517 £2 Liquid + 7LiF-6UF4—7LiF'6ThF4 (ss) Liquid + 3LiF-ThF4 (ss) + 7LiF+6UF ,— . 7LiF-6ThF4 (ss) v 20 45 883 +2 Liquid + UFA-ThFA (ss) Liquid + LiF-4UF4—LiF-4ThF4 (ss) 21.5 21.5 610 £3 Liquid + LiF-4UF4-LiF~4ThF4 (ss) Liquid + 7LiF°6UF4-7LiF-6ThF4 (ss)© 22 6 495 12 LiF + liquid LiF + liquid + 7LiF+6UF ,— 7LiF-6ThF4 (ss) 487 £2 LiF+|iquid+7LiF-6UF4-— 7LiF'6UF4—7LiF-6T|1F4 (ss)€ + LiF¢ TLiF-6ThF (ss)© 24 4 488 +2 7LiF«6U l""‘--7LiF-6ThF4 (ss) + LiF + 7LiF-6UF4—7LiF’-6ThF4 (ss) LiF + liquid 25 2 487 £ 2 Liquid + LiF + 7LiF-6UF ,— LiF + 7LiF°6UF4-—7LiF-6ThF4 (ss) 7LiF-6Th F4 (ss) 25 3 491 3 Liquid + LiF + 7LiF'6UF4- LiF + 7LiF-6UF4-7LiF-6ThF4 (ss) 7Lii'-'-6ThF4 (ss) 25 15 615 +3 Liquid + LiF-AUF“—LiF-ciThF4 (ss) Liquid + 7LiF-6UF4--7LiF~6ThF4 (ss) 613 +2 Liquid + LiF-4UF4—LiF-4ThF4 (ss) Liquid + 7LiF°6UF4—7LiF-6ThF4 (ss) 607 6 Liquid + LiF°4UF4—LiF-4Th F4 (ss) Liquid + 7LiF°6UF4-7LiF-6ThF4 (ss) 26 2 489 12 Liquid + LiF + 7LiF-6UF4— LiF + 7LiF'6UF4—7LiF-6ThF4 (ss)© 7Li|"'°6'|'hF4 (ss)€ 26.5 2 495 £2 Liquid + 7LiF+-6U F4—7LiF-6ThF4 (ss) Liquid + LiF + 7LiF+-6UF ,— JLiF<6ThF ; (ss) 490 +3 Liquid+LiF+7LiF'6UF4-— LiF+7LiF-6UF4--7LiF-6'|'hl"4 (ss) 46 7LiF«6Th F4 (ss) Appendix (continued) Composition a (mole %) Temperature ©C) Phases? Above Temperature Phases? Below Temperature UF, ThF, 28 10 610 £3 Liquid + LiF'4UF'4-—LiF-dThF4 (ss) Liquid + 7LiF'6UF4-7LiF-6ThF4 (ss) 30 10 611 £2 Liquid + LiF-4UF ,~LiF+4ThF (ss) Liquid + 7LiF-6UF ,~7LiF-6ThF , (ss) 30 50 827 5 Liquid + UF ,-ThF, (ss) Liquid + UF ,-ThF, (ss) + LiF-4UF ;- LiF-4ThF , (ss) 33 10 604 +3 Liquid + LiF-4UF ,~LiF-4ThF , (ss) Liquid + 7LiF+6UF ,~7LiF:6ThF, (ss) 33), 33% 862%2 Liquid + UF-ThF (ss) Liquid + LiF+4UF ,—LiF-4ThF, (ss) 39 4 612 3 Liquid + LiF-4UF ,~LiF+4ThF , (ss) Liquid + 7LiF+6UF ;~7LiF+-6ThF , (ss) 45 20 859 +3 Liquid + UF ,-ThF , (ss) Liquid + LiF-4UF ,~LiF+-4ThF , (ss) %The uncertainty in temperatures indicates the temperature differences between the quenched samples. bOnIy phases found in major quantity are given. Minor quantities of other phases resulting from lack of complete reaction between solids or from trace amounts of oxide impurities are not noted. Glasses or poorly formed crystals assumed to have been produced during rapid cooling of liquid were found in those samples for which the observed phase is indicated as ‘‘liquid.” “Most of the phases were identified by optical microscopy; in addition, this phase was identified by x-ray diffrac- tion. 47 C. E. Center Biology Library Health Physics Library Central Research Library Reactor Experimental Engineering Library Laboratory Records Department . Laboratory Records, ORNL, R.C. . A. M, Weinberg L. B. Emlet (K-25) J. P. Murray . J. A, Swartout . E.H. Taylor E. D. Shipley S. C. Lind M. L. Nelson C. P. Keim . J. H. Frye, Jr. 38. R. S. Livingston 39. H. G, MacPherson 40. F. L. Culler 41. A. H. Snell 42. A. Hollaender 43, M. T. Kelley 44, K. Z. Morgan 45, C. F. Weaver 46. A. S. Householder 47. C. S. Harrill 48, C. E. Winters 49. H. E. Seagren 50. D. Phillips 51. F. C. VonderLage 52, D. S. Billington 53. J. A. Lane 54, M. J, Skinner 55. W. H. Jordan 56. G. E. Boyd 57. C. J. Barton 58. J. P. Blakely 59. M. Blander 60, F. F. Blankenship 61. C. M. Blood 62, S. Cantor 63. R. B. Evans 64. H. A. Friedman 65. R. A, Gilbert 66. W.R. Grimes INTERNAL DISTRIBUTION 67, 68. 69. 70. 71, 72, 73. 74, 75. 76. 77. 78. 79. 80. 81. 82-91. 92, 93. 94, 95, 96. 97. 98. 99. 100. 101, 102, 103. 104, 105. 106. 107. 108, 109. 110, 111, 112, 113. 114, 115, 116. 117. 118, 119, 120. 121, 122, ORNL-2719 Chemistry-General TID-4500 (14th ed.) H. Insley F. Kertesz S. Langer R. E. R. E. Moore G R L. J. J. R. N. R. B. v, R. G. M. S. R. A. G. M. A, L. R. G. W, A, L. F. E. R. R. W, R. J. A, W. D. R. J. G. W. H. H. . J. F G. D. H. J. V. A, J. T. E. M. A. Da E. S. P, T. J. G. R. w. D. P. A, R. S. P. A. K. B. C. S. F. E. E. T. l. H. E. F L. Meadows Nessle . Newton Overholser Redman Shaffer Sheil Smith Strehlow Sturm Watson Bredig tz Minturn Dworkin Smith Robinson Miller Alexander Dickison Keilholtz Bettis Milford Charpie Ergen Lindaver White Ferguson Blanco Long Cathers Carr, Jr. Goeller McDuffie Marshall 49 138, 139, 138. 139. 140-142, 143, 144, 145-631. 123. J. S. Gill 131, P. M. Reyling 124, L. O. Gilpatrick 132. J. Ricci (consultant) 125, C. F. Baes 133. C. E. Larson (consultant) 126. B. A. Soldano 134. P. H. Emmett (consultant) 127. W. E. Browning 135. H. Eyring (consultant) 128. M. J. Kelly 136. G. T. Seaborg (consultant) 129. J. O. Blomeke 137. ORNL - Y-12 Technical Library 130. G, C. Williams Document Reference Section EXTERNAL DISTRIBUTION Division of Research and Development, AEC, ORO Oak Ridge Institute of Nuclear Studies University of Cincinnati (1 copy each to H. S. Green, J. W. Sausville, and T. B. Cameron) Division of Research and Development, AEC, ORO Odk Ridge Institute of Nuclear Studies University of Cincinnati (1 copy each to H. S. Green, J. W, Sausville, and T. B. Cameron) E. F. Osbormn, Pennsylvania State University G. W. Morey, 5806 Bradley Blvd., Bethesda, Md. Distribution as shown in TID-4500 (14th ed.) under Chemistry-General category (19 4]