DEVELOPMENT OF CORROSION-RESISTANT NIOBIUM-BASE ALLOYS

The hot-water corrosion resistance and mechanical properties of niobium and a number of its alloys were evaluated relative to their usefulness in pressurized-water thermal reactors. Unalloyed niobium was found to be rapidly attacked by 600 and 680 deg F water and 750 F steam. A number of alloying additions were found which markedly improve the corrosion resistance of niobium. Of these, binary and ternary combinations of chromium, molybdenum, titanium, vanadium, and zirconium were among the most effective. Many of these alloys exhibited as low or lower weight gains than those obtained for Zircaloy-2 under similar test conditions. Most of the niobium-base alloys tested for strength exhibited excellent resistance to creep at temperatures up to 1200 deg F under stresses through 20,000 psi. (auth