Tailored refractory W-alloys for fusion-based additive manufacturing

Additive manufacturing (AM) of refractory tungsten (W) alloys has been limited by their high melting point, intrinsic brittleness, and poor printability. With increasing demand for refractory materials in extreme and high-temperature environments, laser powder bed fusion (L-PBF) AM has emerged as a promising route for fabricating W-based components, provided the alloys 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 using CALPHAD and coupled heat-transfer-material-flow simulations to enhance printability while achieving superior mechanical properties. Owing to the highly non-equilibrium nature of L-PBF, the process produces rapidly solidified microstructures that differ significantly from equilibrium conditions. In conventional W-Cr alloys, spinodal decomposition dominates microstructural evolution; however, under the high cooling rates of L-PBF, this decomposition is restricted to a limited fraction, primarily in the mid-section of the build. This study demonstrates that the spinodal fraction can be effectively tuned through optimization of AM process parameters and post-processing heat treatments, enabling improved strength-ductility synergy. The results establish a pathway for designing AM-compatible refractory alloys tailored to application-specific requirements.