Patent Number: 049869574
Section: description

EXAMPLE I Table I lists several examples of alloys of the present invention, along with three entries at the bottom of the table which are Zircaloy 2 alloys in three different cold-rolled and heat treated states. These alloys were tested in water containing 8 ppm oxygen at 288.degree. C. and 1500 psig, conditions similar to a reactor operating temperature and pressure but absent the radiation, to evaluate the resistance to uniform corrosion. It can be seen from the results in Table I that the tested alloys of the present invention exhibit excellent resistance to uniform corrosion. Although tested for much longer periods of time, the tested alloys of this invention exhibited corrosion rates comparable to those of the Zircaloy 2 specimens. None of the specimens tested under these conditions exhibited any sign of the formation of nodular corrosion products. TABLE I ______________________________________ UNIFORM CORROSION TEST IN WATER AT 288.degree. C., 1500 psig, 8 ppm OXYGEN Weight Gain Elapsed Time Sn Cu Ni Fe (mg/dm.sup.2) (Hours) ______________________________________ 1.5 0.1 0.1 0.1 25 14,849 1.0 0.1 0.1 0.1 25 14,849 2.0 0.1 0.1 0.1 25 14,849 1.59 0.11 0.11 0.13 27 13,309 1.61 0.13 0.13 0.14 21 5,077 Z2 (Zircaloy 2, cross-rolled 11.0 1,000 commercial plate) 13.2 1,700 Z2 with 750.degree. C./16 hr. anneal 11.0 1,000 15.0 1,700 Z2 with Beta Quench 15.0 1,000 17.0 1,700 ______________________________________ EXAMPLE II Table II reports the results of tests conducted to determine the susceptibility of the alloys of the present invention to nodular corrosion. The tests were performed using steam at 510.degree. C. and 1500 psig. In the laboratory, these same test conditions induce the formation of the nodular corrosion product on Zircaloy alloys which have been given a 750.degree. C./48 hour anneal, and is also identical to the nodular corrosion found on sometimes Zircaloy after being used in reactor service. For purposes of comparison, the weight gains of annealed Zircaloy samples under the same test condition were on the order of several thousand milligrams per square decimeter. The tests in Table II were also performed on samples in various cold-reduced and heat treated states. The results in Table II provide an indication that the corrosion resistant properties of these alloys are relatively insensitive to the heat treatment state of the specimen. However, alloys having the solute composed of copper and nickel preferably are heat treated. Some compositions were tested using specimens in cold-rolled plate form, both with and without a subsequent anneal. Two compositions were tested only after having been cold-reduced and annealed. The 750.degree. C. anneal for 48 hours, which all of the tested samples were subjected to, is the heat treatment which strips the Zircaloy 2 alloy of its resistance to nodular corrosion under the laboratory steam tests. All of the weight gains recorded in Table II are far superior to the results obtained when sensitized Zircaloy 2 annealed at 750.degree. C. for 48 hours is tested. Most of the tested alloys of the present invention produced weight gains of less than 100 milligrams per square decimeter, and one produced a weight gain of 107 mg/dm.sup.2. As previously mentioned, weight gains reported in tests of sensitized Zircaloy specimens under the same test times and conditions are in the order of several thousand milligrams per square decimeter. In addition to the reduced weight gains evidenced in the alloys of the present invention, none of these alloys showed any sign of formation of nodular corrosion products. Under the test conditions, these alloys clearly provide improvement in resistance to nodular corrosion. TABLE II ______________________________________ WEIGHT GAIN AFTER EXPOSURE TO STEAM AT 510.degree. C. 1500 psig FOR 24 HOURS Weight Gain (mg/dm.sup.2) Zr Alloy Composition Cold Rolled 0.1" Plate Weight/Percent 750.degree. C./48 hr. Sn Cu Ni Fe As Rolled Anneal ______________________________________ 1.5 0.2 0.1 865 87 1.5 0.1 0.2 367 107 1.5 0.1 0.1 0.1 58 70 1.5 0.08 0.08 0.08 61 76 1.5 0.12 0.12 0.12 53 69 1.0 0.1 0.1 0.1 52 69 2.0 0.1 0.1 0.1 60 81 1.61 0.13 0.13 0.14 * 78 1.59 0.11 0.11 0.13 * 65 ______________________________________ *Not tested.