Tailored Refractory W-Alloys for Fusion-Based Additive Manufacturing

Additive manufacturing (AM) of refractory tungsten (W) alloys has been restricted by their high melting point, inherent brittleness, and poor printability. As the demand for refractory metals in high-temperature and extreme environments grows, laser powder bed fusion (L-PBF) AM has emerged as a promising method to fabricate W-based components, provided alloys that can be designed for crack-free, dense printing. To address these challenges, a W-Cr-C alloy was designed and developed for L-PBF AM by CALPHAD and heat transfer–material flow simulations to enhance printability and exhibit superior mechanical properties. L-PBF AM is a highly non-equilibrium process that produces rapidly solidified microstructures. In conventional W-Cr alloys, spinodal decomposition dominates the microstructural evolution. In this study, post-heat treatments were employed to control spinodal features and enhance the strength-ductility synergy of L-PBF AM printed W-alloy. Although the high cooling rates in L-PBF restrict spinodal decomposition to a small fraction, this fraction can be effectively tuned through AM process parameters optimization and post-process heat treatments. By engineering a hierarchical microstructure to enhance strength, while incorporating appropriate alloying elements to improve ductility, the mechanical performance of L-PBF fabricated W-alloys can be significantly enhanced. This approach establishes a pathway for the design of refractory alloys compatible with AM and optimized for application-specific requirements.