Investigation on melting characteristics, mechanical properties and microstructure of Ta-W alloy fabricated via LPBF

Ta-W refractory alloys have attracted increasing attention for extreme applications owing to the excellent high-temperature performance. Laser powder bed fusion (LPBF) overcomes the challenges of manufacturing complex Ta-W structures. However, the high melting point and limited laser absorption hinder stable forming during LPBF processing. This paper investigated the effects of laser power and scanning speed on melt-pool morphology, two-phase region and track stability based on single-track melting and printing, and a stable single-track processing window of 200-250 W and 400-500 mm/s was identified. The forming behavior of the Ta-5W alloys was further evaluated based on volume energy density (VED), although similar VED values resulting from different power-velocity combinations produced different defect morphologies. Microstructural observations indicated that cooling variations caused by scanning speed affect grain morphology, while variations in recrystallization behavior induced by laser power resulted in local residual stresses. The Ta-5W alloy fabricated under optimized parameters of 250 W and 500 mm/s achieved a tensile strength of 667.3 MPa and an elongation of 20.51%. This study provides a process window and analytical foundation for the fabrication of Ta-W refractory alloys using LPBF.