IMPROVED ZIRCONIUM ALLOYS. Quarterly Report, January 1, 1963-March 31, 1963

On the basis of 4800 hr exposure to 680 l F water, a number of ternary compositions were shown to have corrosion resistance superior to Zircaloy-2. In addition, the strength and hydrogen pickup properties of the alloys were generally improved over Zircaloy-2. The promising alloys were based on the binary materials Zr- 1Sb, Zr- 1Cr, Zr0.5Nb, and Zr-0.5Sn to which small percentages of Te, Ge, Cr, or Fe were added. At present, 680 l F water corrosion data for an exposure time of 5000 hr are available for the modified ternary alloys. Development of materials for potential service in 750 and 900 l F steam proceeded in a manner similar to that for 680 l F water application. On the basis of corrosion resistance and strength, the alloys Zr3Cr- 1Fe, Zr-3Cr- 0.25Te, and Zr- 1V- 1Fe were considered highly promising and initially acceptable. However, hydrogen pickup properties, which were about the same as Zircaloy-2, were judged as unacceptable. In an attempt to improve this characteristic as well as to further enhance corrosion resistance and strength, an additional series of ternary alloys was prepared. The compositions studied in 900 l F steam did not exhibit satisfactory corrosion resistance. (P.C.H.