FACTORS AFFECTING THE COMPATIBILITY OF LIQUID CESIUM WITH CONTAINMENT METALS

Mechanisms associated with the corrosive attack of refractory metal alloys and superalloys by liquid cesium have been investigated. The superalloys, Haynes-25 and TD-Nickel, were exposed at 1800F and the refractory metal systems, Mo-12Ti, Cb-1Zr, Ta-10W and Cb-25Ta12W-12Zr were exposed at 2100F and 2500F. Pure nickel and pure zirconium were employed as dissimilar metal additions in some tests. Boiling reflux tests of each alloy candidate were performed. In the case of the refractory alloys, the boiling temperatures were 2100 and 2500F, while 1800F was the test temperature employed for Haynes-25 and TD-Nickel capsules. The Haynes-25 and the TD-Nickel show some dissolution in cesium, and a measurable amount was experienced by Mo-12Ti at 2500F. The tantalum and columbium alloys show little in the way of cesium attack at 2100F. Metal solubility studies showed the solubility of the refractory metals columbium and molybdenum to be approximately 10-20 ppm at 2500F. Synergistic effects appear to control solubility in some cases.