Ultrahigh-Vacuum Creep Behavior of Columbium and Tantalum Alloys at 2000 degs and 2200 degs F for Times Greater Than 1000 Hours
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER
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Creep tests of 1000 hours and greater were conducted at 2000 degrees and 2200 degrees F on six commercially available refractory alloys at pressures of 10 exp -8 to 10 exp -9 torr. The creep behavior of three columbium alloys, FS-85 Cb 28Ta 10W 1Zr, D-43, Ch 10W 1Zr 0.1C, and Cb-752 Cb 10W 2.5Zr, and three tantalum alloys, T-222 Ta 9.6W 2.4Hf 0.01C, T-111 Ta 8W 2Hf, and Ta-10W 90Ta 10W was determined stress-to-density ratios of 2.6x10exp 4 and 1.3x10exp 4 inches, respectively, at 2000 degrees and 2200 degrees F. Comparison of creep behavior on the density-compensated basis shows that the tantalum alloy T-222 was the most creep resistant material evaluated. A total creep strain of only 0.1 percent resulted from testing this alloy for 5000 hours. The relative order of creep resistance, on a density-compensated basis, was the same for the materials evaluated at 2000 degrees and 2200 degrees F T-222, Ta-10W, D43, FS-85, T-111, and Cb-752.
- Metallurgy and Metallography