Mechanical Testing Studies on Niobium-1%zirconium in Association with Its Application as Cell Wall Material in an AMTEC Based Radioisotope Space Power System

A new generation of radioisotope space power systems based on AMTEC (Alkali Metal Thermal to Electrical Conversion) technology is presently being developed. The future application of this technology, as the electrical power system for outer planet deep space missions, is ultimately dependent on it being robust enough to withstand the mission’s operational environments (high temperatures, dynamic loadings, long mission durations etc). One of the critical material selections centers on the cell wall whose physical and chemical properties must provide it with sufficient strength and material compatibility to successfully complete the mission.

Niobium-1%zirconium has been selected as the cell wall material for application in the new radioisotope space power system being developed as part of the ARPS (Advanced Radioisotope Power System) program being supported by the U.S. Department of Energy and NASA. The emphasis of this paper is on the determination of some of the mechanical properties of niobium-1%zirconium as a function of test atmosphere and test temperature. Nb-1%Zr test samples and tensile bars were fabricated and exposed to various high-temperature heat treatments under either vacuum or argon gas containing low concentrations of oxygen. The results show a measurable change in various mechanical and physical properties of Nb-1%Zr as a function of time at temperature and test atmosphere.