Effect of process parameters on the microstructure and mechanical properties of Ta-10W alloy produced via electron beam powder bed fusion

Electron beam powder bed fusion (EB-PBF) is advantageous for additive manufacturing of tantalum-tungsten (Ta-W) alloys, offering advantages such as in-situ heat treatment and reduced residual stresses. However, controlling the microstructure and mechanical properties through process parameter optimization remains a significant challenge. This work studied the influence of process parameters on the microstructure and mechanical properties of the EB-PBFed Ta-10W alloy. The results reveal a distinct transition in melt pool morphology and surface quality governed by scanning speed, while volumetric energy density (VED) dictated the defect mode (Lack of Fusion (LoF) vs. keyhole). A unique scanning speed-dependent texture transition was observed: high scanning speed promoted a shift from <001>//BD to <110>//BD texture, whereas low scanning speed favored strong <001>//BD columnar growth. Mechanically, the as-built samples exhibited excellent compressive ductility (>70% strain) but severe tensile brittleness (<0.5% elongation) in the transverse direction due to residual stress and defect sensitivity. Annealing at 1300 °C significantly restored tensile ductility (up to 12% elongation) primarily through residual stress relief and dislocation recovery, rather than pore closure. This work demonstrates that optimizing scanning strategies to control texture and employing post-thermal treatments are crucial for achieving high-performance Ta-10W components via EB-PBF.