Dispersion Strengthened Refractory Metal Claddings for NTP

Nuclear Thermal Propulsion (NTP) has been identified as a critical technology needed for human missions to Mars due to its high specific impulse (Isp). An essential aspect of the program is to develop a robust, stable fuel element. The current element configuration is comprised of a cermet fuel (i.e., Mo-UN) and refractory metal claddings (Mo or Mo-W). Due to high temperature exposure, significant grain growth can occur resulting in undesirably large Mo and Mo-W grains. To address this concern, dispersion strengthened alloys are needed to minimize grain growth in both the claddings and cermet matrix. Recently, Plasma Processes has developed innovative dispersion strengthened Mo-Re and W-Re alloys for high temperature applications. These alloys have shown significant improvements in grain refinement, mechanical properties, and performance. However, Re is not desired for NTP. Therefore, during this effort, dispersion strengthened Mo and Mo-W alloys will be developed. Emphasis will be placed on the development of a stable dispersion strengthening phase (thermodynamic and neutronic), and techniques to assure uniform distribution within the refractory metal matrix. To aid in this development, Plasma Processes will partner with the University of Tennessee. Material for characterization and preliminary mechanical properties testing will be produced using innovative Vacuum Plasma Spray forming, and a dispersion strengthened Mo cladding will be produced to demonstrate proof-of-concept. During Phase II, the dispersion strengthened alloys will be optimized and extensive properties testing will be performed.nbsp; Both Mo and Mo-W will be included in Phase II. Feedstock powder will also be produced for alternative fabrication techniques such as Spark Plasma Sintering (SPS) to allow the fabrication of fine-grained cermet fuel. Dispersion strengthened Mo and Mo-W claddings and cermet segments will be produced and delivered to NASA for testing in CFEET and NTREES during Phase II