Consulting scientist, Metallurgy and Composites Laboratory, Lockheed Palo Alto Research Laboratories, Palo Alto, Calif.
Analytical engineer, United Aircraft Corp., Hartford, Conn.
Uncoated Ta-17W and C129Y alloys and coated Ta-10W, C103, and C129Y alloys have been evaluated for short-time creep behavior at 2600 to 3200°F. The time for creep strains of up to 2 percent has been measured and the results have been used to derive empirical equations that predict short-time creep life in this temperature range. The equations give estimates of the time-to-creep strains of up to 2 percent at stress levels that will produce the maximum strain in 60 min or less. Silicide-base coatings appear to add to the creep strength of coated Ta-10W but have little added effect on the strength of the columbium-base alloys. The creep behavior of coated metals can be analyzed by the same empirical methods as those used for uncoated substrates. The results show that commercially available silicide coatings protect the substrate from oxidation with creep strains of up to 2 percent on exposures of 1 to 1½ h in this temperature range.
Paper ID: JTE10116J