Effects of casting parameters and impurity concentrations on as-cast U-10Mo

This work investigates the effects of casting parameter changes on as-cast uranium-10 wt% molybdenum (U-10Mo) alloys on a 1-2 kg scale. A commercial tilt-pour vacuum induction melting system was utilized to study the effects of casting atmosphere, total heating time, hold time at maximum temperature, mold temperature, and crucible type on as-cast U-10Mo impurities and dendrite size. Fourteen plates of differing geometry were cast and analyzed for carbon, oxygen, hydrogen, and nitrogen impurities, as well as molybdenum content. Primary dendrite lengths (PDL) in the microstructure are quantified. A statistical evaluation was performed to identify key carbon and oxygen relationships with operating parameters, impurities, and PDL. Additional factors investigated include crucible material, time at maximum temperature, and total heating time. Zirconia crucibles reduced carbon content on average by 35 % over traditional graphite crucibles. There was statistically relevant associations between carbon and oxygen content, oxygen content and maximum temperature hold time, mold temperature and PDL, and between PDL, maximum temperature hold time, and mold temperature.