New strategy for strength and ductility synergy enhancement in Ta-12W refractory alloy: selective laser melting + rolling + inter-pass electrical treatment

Vollständiger Abstract

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Abstract Tantalum-tungsten alloys are critical for extreme aerospace applications. However, oxidation sensitivity and processability limitations associated with conventional manufacturing routes severely constrain the mechanical performance and manufacturability of tantalum-tungsten alloys. This study proposes a new process for fabricating Ta-12W alloys using “selective laser melting + rolling + inter-pass electrical treatment” (ET-AMR), which achieves a synergistic enhancement of both strength and ductility. First, a substrate with fine grains, high density, complete element diffusion, and no segregation was fabricated using selective laser melting technology. Subsequent multi-pass rolling refined the microstructure and stored substantial deformation energy along the columnar grain growth direction. Inter-pass electrical treatment facilitated dislocation disentanglement, alleviated stress concentration, and induced strain delocalization. The combined effect of rolling and pulsed current effectively repaired internal pores and cracks, reducing porosity from 0.15% to 0.002% and significantly improving material densification. Specific annealing procedures further enhanced the mechanical properties and grain evolution behavior of the Ta-12W alloy, with tensile strength increasing by 63% and elongation approximately 3.3 times higher than that of the as-built state, reaching 986 MPa and 14.8%, respectively. After annealing, coarse–fine grain heterostructures and subgrain–recrystallized heterostructures were formed, while columnar grains were transformed into layered equiaxed grains along the build direction. During plastic deformation, the heterogeneity in grain size and type led to dislocation pile-up, further enhancing heterogeneous deformation-induced strengthening and promoting a synergistic increase in ductility under high strength. This study provides new insights into the high-performance fabrication and development of tantalum-tungsten alloys.