Laser Powder Bed Fusion Additive Manufacture Nb1Zr Development

Next generation fission and fusion nuclear reactors require materials that can withstand operating temperatures greater than 500 °C, neutron irradiation doses of up to 200 displacements per atom (dpa), and potentially corrosive coolants such as the alkali liquid metals sodium, lithium, and NaK (Na33K eutectic alloy). Refractory alloys, such as Nb1Zr (Nb-1wt%Zr) and Molybdenum alloy TZM (Mo-0.5wt%Ti-0.08wt%Zr) have been traditionally considered viable candidates for advanced fission and fusion reactor concepts. However, it is relatively difficult to generate complex geometries of interest from these alloys using traditional manufacturing methods. In addition, there needs to be a concentrated effort to address refractory metal challenges at elevated temperature operation. In order to generate complex geometries of interest, modern manufacturing techniques are considered to increase the technological readiness level (TRL), cost-effectiveness, and schedule savings. This work focused on the continued development of laser powder bed fusion (L-PBF) additive manufacturing (AM) to improve both design flexibility, evaluate microstructure and properties, and ultimately accelerate the TRL and qualification of these processes and alloys for components to potentially be put into service. Niobium alloy Nb1Zr was identified through a down-selection process outlined in previous reports as a candidate to develop in L-PBF AM. Historically, Nb1Zr had been explored for high temperature fast spectrum fission reactors for both terrestrial and space applications. Molybdenum alloy TZM has also been considered for these reactor concepts due to exceptional high-temperature strength, creep resistance, and stability under irradiation. L-PBF AM of TZM has previously been investigated at LANL under the Microreactor program, NASA, ORNL, and in academia. However, due to the crack prone nature of TZM, L-PBF AM of TZM resulted in significant microcracking and additional development is required to pur. Authors: Mireles, Omar Roberto [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0009000770075234); Kanies, Bryant Alan [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000282327941); Brand, Michael J. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000314437097); Montoya, Robin Adriana [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000347225285). DOE Contract: 89233218CNA000001. Subjects: 36 MATERIALS SCIENCE; 42 ENGINEERING; Additive Manufacturing; Laser Powder Bed Fusion; Nb1Zr