A Comparison of Niobium Alloys C103 and Nb521

C103 (Nb-10Hf-1Ti [wt%]) has been the dominant niobium alloy in United States aerospace applications due to its well-established record (excellent weldability, room temperature formability, and adequate high-temperature strength. However, Nb521 (Nb-5W-2Mo-1Zr [wt%]) offers significantly increased strength at elevated temperatures. Compared to C103, Nb521 has been reported to have 2-3 times higher tensile strength at 1600°C. This improvement comes alongside good conventional manufacturability and promising printability using powder-based additive manufacturing (AM) techniques. This study investigates the high-temperature mechanical properties of C103 and Nb521 produced via laser powder-bed fusion (L-PBF). Uniaxial tensile testing was conducted in a high-vacuum environment at various temperatures to quantify their performance. Microstructural analysis was performed to correlate the observed mechanical behavior with the underlying grain structure and precipitates. The results provide a metallurgical understanding of how the differing chemical compositions of C103 and Nb521 influence their high-temperature properties. This work highlights the need for further research and development of Nb-based alloys produced via AM to achieve even greater performance and meet the evolving challenges of the future aerospace industry.