Alkaline‐Earth‐Fluoride—LaF 3 Systems with Implications for Electroslag Melting

Liquidus and solidus curves in the systems CaF 2 ‐LaF 3 , SrF 2 ‐LaF 3 , BaF 2 ‐LaF 3 , and MgF 2 ‐LaF 3 under ½ atm helium pressure were determined by thermal analysis as an aid in the selection of suitable fluxes for electroslag melting of reactive metals. The systems CaF 2 ‐LaF 3 , SrF 2 ‐LaF 3 , and BaF 2 ‐LaF 3 each contain (1) one eutectic, (2) no intermediate phases, and (3) two solid solutions whose lattice parameters vary linearly with composition. The liquidus curves in the systems SrF 2 ‐LaF 3 and BaF 2 ‐LaF 3 exhibit maxima. The system MgF 2 ‐LaF 3 is of the simple eutectic type with no detectable terminal solid solutions. The smallest temperature interval observed between a fluoride‐flux liquidus and the melting point of Ti occurs at the dystectic composition in the system SrF 2 ‐LaF 3 . Differences in density between metal and flux are more favorable in the system BaF 2 ‐LaF 3 than in pure LaF 3 . These observations suggest potential advantages of using fluxes from the systems studied for electroslag melting of reactive metals.