A U + 5 wt.% Al powder (written U-5Al), manufactured by centrifugal atomization, was used in this study to assess the feasibility of densifying UAlx + Al powder mixtures by Spark Plasma Sintering (SPS) and obtaining a final composition with a minimum content of UAl2 that meets specifications of targets for 99Mo production. The microstructure of the U-5Al powder was studied first and mainly consists of a mixture of UAl2 primary dendrites and α-U phase. Three SPS conditions differing in terms of UAlx/Al volume ratio and dwell time at 800 K were tested. The sintered discs were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. A very quick transformation of the U-5Al particles into a mixture of aluminides (UAl2 + UAl3 + UAl4, referred to UAlx) was evidenced: only a few minutes were sufficient to transform the U-based particles into a mixture of aluminides containing about 80 wt.% of UAl3. According to these first tests, this new highly versatile manufacturing process could advantageously replace the conventional method of producing targets, subject to technical adjustments and parametric studies.
Iltis et al. (Wed,) studied this question.