High-temperature thermal analysis of the systems LaF3-YF3, SrF2-YF3 and MgF2-YF3.
Nafziger-RH; Lincoln-RL; Riazance-N
J Inorganic Nuclear Chem 1973 Feb; 35(2):421-426
Thermal analysis experiments have established high-temperature phase relations in three systems containing YF3 having potential use as fluxes for electroslag melting of reactive metals. The LaF3-YF3 system is characterized by (1) a eutectic occurring at 81 wt percent YF3 and approximately 400 deg C below the LaF3 melting point, (2) a low-temperature hexagonal compound, (3) an extensive LaF3 solid solution, and (4) limited YF3 solid solution. A hexagonal compound with a range of composition, and whose x-ray lattice parameters increase with increasing SrF2 content, is stable in equilibrium with liquid in the SrF2-YF3 system, resulting in the presence of two eutectics. A small liquidus-curve maximum occurs in the region where an extensive fluorite solid solution is the primary phase. No discernible solid solubility of SrF2 in YF3 was detected. The MgF2- YF3 system contains one eutectic with limited terminal solid solution and a possible low-temperature compound. Due primarily to higher liquidus temperatures, systems containing LaF3 possess a wider range of suitable electroslag fluxes than do systems containing YF3. However, an optimum combination of high liquidus temperature and low electrical conductivity indicates that selected compositions containing relatively low YF3 in these systems may provide useful fluxes. Compounds present in systems containing YF3 would probably not find uses in the electroslag process because of their relatively low stability temperatures.
Yttrium-compounds; Thermal-effects; Thermal-reactions; Metal-compounds; Metals; Lanthanum-compounds; Strontium-Compounds; Magnesium-compounds
OP; Journal Article
Journal of Inorganic and Nuclear Chemistry