The Pu-Ta (Plutonium-Tantalum) system

The assessed Pu--Ta phase diagram is shown. An enlargement of the region from 0-2 at.% Ta is shown. The solubility of Ta in liquid Pu was measured at selected temperatures between 700-950 deg C. The solubility of Ta in liquid Pu at 1000 and 2000 deg C was reported, referring to unpublished work at Los Alamos National Laboratory. It was proposed that the phase diagram was a simple eutectic, although it was noted that no eutectic microstructure was observed in Pu--Ta alloy samples after solidification and that the slight lowering of the melting temperature of Pu (which would be indicative of a eutectic reaction close to pure Pu) could have been the result of the presence of small amounts of impurities. Recently, the Pu--Ta system was reviewed and it was assessed to be a simple eutectic reaction very close to 100% Pu and at 640 deg C.