Refractory Metal Alloyed Powders by Volatile Halide-Liquid Metal Reaction

Abstract

The use of a modified Kroll-type of process for the production of intermetallic compounds in the Nb-Sn and Ti-Al systems is considered. Modifications to the standard Kroll process are necessary to allow for sequential reaction of metal product and excess metallic reducing agent after the initial reduction of the volatile chloride. The Nb-Sn system is considered first and it is shown that control of chloride vapour pressure and temperature of reaction may be used to control the morphology of the intermetallic products. The Ti-Al system is considered as a second example. It is shown that an analojous process to that used for Nb-Sn compounds may be used for the titanium aluminides. Again, it is demonstrated that control of reaction temperature and chloride vapour pressure can be used to control the norphology of the particulate product. However, care must be taken to avoid contamination with lower chlorides in the Ti-Al system.