PREPARATION OF YTTRIUM METAL BY REDUCTION OF YTTERIUM TRIFLUORIDE WITH CALCIUM

3 The preparation of yttrium metal by the reduction of yttrium trifluoride with calcium is described. Alternate methods employing the formation of a low melting Y-Zn or Y-Mg intermediate alloy are evaluated and data on chemical and microscopic purity of the resulting metal are presented. INTRODUCTION The purpose of this investigation was to explore the possibilities of developing new methods for the preparation of yttrium metal. Daane and Spedding (1) have reduced yttrium trifluoride with calcium by heating the mixture in a tantalum crucible above 1500°C. Yields of greater than 99% were obtained and a tantalum contamination of 0.05 to 0.1 weight per cent was reported. Trombe and Mahn (2) prepared yttrium metal by a high temperature electrolysis of YCl~. The reduced metal dissolves in a molten magnesium-cadmium cathode, forming a ternary alloy containing approximately 24 w/o Y, 56 w/o Mg and 20 w/o Cd. This alloy is heated to 1200°C in an argon atmosphere and all of the cadmium and a major portion of the magnesium is distilled off, leaving a residue of ,yttrium metal. Two methods of preparing yttrium metal by the reduction of YF3 with calcium have been investigated. One of these . methods is a bomb reduction process in which ZnF2 is added to the reduction charge. The reduction of the ZnF2 witn calcium supplies additional heat to the system, enabling the zinc to alloy with the yttrium to form a lower melting massive alloy. This alloy is immiscible with the molten slag product. The zine may then be volatalized from the yttrium by heating in vacuo with a sponge product ,resulting.