Additive Manufacturing of Refractory Metal Alloys for Nuclear Thermal Propulsion Components

For long duration deep space missions nuclear thermal propulsion (NTP) enable much superior propulsion capability compared to chemical propulsion, reduces travel time for deep space missions, and circumvents the primary concern of crew exposure to hazardous deep space radiation. A critical requirement for specific components of such reactors is the high temperature capability of structural materials to withstand temperatures greater than 1500 K over long durations. Certain refractory metal alloys are prime candidates for such applications due to their low creep rates, strength retention at high temperatures, and no embrittlement due to irradiation. However, the primary challenge associated with such alloys is their low room temperature ductility and extreme difficulty in manufacturing these alloys to desired shapes and with intricate features. To address this challenge GeoPlasma Research proposes to develop the necessary refractory metal feedstocks and a corresponding low temperature Fused Deposition Modeling (FDM) Additive Manufacturing (AM) technology that will overcome the problems associated with traditional manufacturing of refractory alloys and enable manufacturing of NTP components. During Phase 1 GeoPlasma Research will concentrate on refractory alloys dispersion strengthened by thermodynamically stable phases. The competitive advantage of the proposed GeoPlasma Research technology includes combination of a high strength refractory metal feedstock and an AM technology that circumvents the issues such as cracking from thermal stresses associated with more traditional laser or electron beam AM technology.nbsp; In addition, the AM technology circumvents microstructural modifications during the build process by avoiding melt solidification of the powder feedstock. Such a cradle to grave process from development of refractory alloy feedstocks to finished products will enable NASArsquo;s NTP requirements for deep space mission.