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Characteristic variation of spark plasma-sintered Ta compacts

In the present study, we applied the SPS process to obtain a tantalum (Ta) compact for a sputtering target. Sintered Ta compacts were characterized with respect to microstructure, relative density, Vickers hardness and phase composition of the inside and the surface. By radio frequency (RF) thermal plasma treatment, a spherical ultra-fine Ta powder was obtained; however, the oxygen content increased due to severe passivation during powder handling. Higher sintering temperature and the RF plasma treatment increased the densification of the sintered compact and also the Vickers hardness. From XRD analysis, only Ta was identified in the cross section of compacts, and TaC formed by the reaction between Ta and the graphite mould was found in the surface of the compacts. The evacuation of the chamber and the reduction by the graphite mould promote the purification of the compact.