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R. E. Thoma, C. F. Weaver, H. bisley and H. A. Friedman
Nuclear Science and Engineering | Volume 19 | Number 4 | August 1964 | Pages 406-411
Technical Paper | doi.org/10.13182/NSE64-A18996
Articles are hosted by Taylor and Francis Online.
The equilibrium phase diagram of the condensed system NaF/BeF2/ThF4 is presented. Liquid/solid phase transitions were found in the temperature range from ∼300 to 1100 C. The phase diagram of the system is based on data obtained from thermal analysis and thermal-gradient-quenching experiments; phase identifications were made employing the polarizing light microscope and the x-ray diffractometer. Thirteen crystalline phases are precipitated as primary phases from molten NaF/BeF2/ThF4 solutions: 4NaF-ThF4, 7NaF·2ThF4, 2NaF·ThF4, 3NaF·2ThF4, α- and β -NaF·ThF4, NaF-2ThF4, 2NaF·BeF2, NaF·BeF2, NaF·BeF2, ·3ThF4, NaF, BeF2, and ThF4 solid solution. The character, location, and temperature of the fourteen invariant and singular points in the system were established. The ternary system is comprised of two subsystems, NaF/2NaF·ThF4/2NaF·BeF2 and 2NaF·ThF4/ThF4/BeF2/2NaF·BeF2, separated by the quasibinary section, 2NaF·BeF2/2NaF·ThF4. The lowest liquidus temperatures in the respective subsystems were found at the eutectics, 72NaF/22BeF2/6ThF4 (mole %), m.p. 509 C, and at 55NaF/43BeF2/2ThF4 (mole %), m.p. 320 C.
