Generation of Long Time Creep Data of Refractory Alloys at Elevated Temperatures (Ninth Quarterly Report, June 26, 1965-September 26, 1965)

Space electric power systems depend upon the use of refractory metals in a variety of component areas. A critical property parameter in the design of these systems is the long-time creep strength at very low partial pressures of oxygen and nitrogen. Since contamination of refractory metal alloys can occur under conditions of 10-6 Torr, vacuums better than 10-8 Torr must be used to obtain creep measurements which are employed in the design of space components. The purpose of this program is to generate long-time creep data on selected refractory alloys which have potential use in advanced power systems. Emphasis has been placed on testing sheet alloys which can be employed for cladding or tubing applications and on forgeable, high-strength turbine alloys. The design of the creep test units capable of operating at vacuums less that 1 x 10-8 Torr and temperatures up to 3200°F has been previously described. This report presents a summary of the creep data obtained to date on tungsten, tungsten-25% rhenium, Sylvania A, molybdenum-base alloys TZC and TZM, columbium-base alloys Cbl32M and AS-30, and the tantalum alloy T-222.