Regular Article

Reactive spark plasma sintering of UAl_x + Al powder mixtures, prospects for manufacturing targets for ⁹⁹Mo production

¹ CEA, DES, IRESNE, DEC, Cadarache, F-13108 Saint-Paul-Lez-Durance, France
² Korea Atomic Energy Research Institute, 111 Daedeok-Daero 989 Beon-Gil, Daejeon, Yuseong-Gu 34057, Republic of Korea
³ Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes – UMR6226, F-35042 Rennes, France

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 25 August 2025
Received in final form: 10 December 2025
Accepted: 16 December 2025
Published online: 11 February 2026

Abstract

A U + 5 wt.% Al powder (written U-5Al), manufactured by centrifugal atomization, was used in this study to assess the feasibility of densifying UAl_x + 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 UAl_x/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 UAl_x) 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.