Effects of processing parameters on densification behavior, microstructure evolution and mechanical properties of W–Ti alloy fabricated by laser powder bed fusion

Abstract Tungsten and its alloys have been widely used in various industries such as nuclear energy, medical shielding, rocket nozzle. However, the intrinsic high melting point and high ductile-to-brittle transition temperature (DBTT) normally limit their further applications. In this work, the transition element Ti modified W alloy was processed by laser powder bed fusion (LPBF) additive manufacturing process with different laser processing parameters. The densification behavior, microstructure evolution, and mechanical performance of LPBF-processed W–Ti samples were systematically investigated through the optimization of laser processing parameters. It indicated that the highest relative density of 99.1% without obvious pores and balling phenomenon were obtained at the applied energy density of 848 J/mm3 with laser power of 350 W and scan speed of 275 mm/s. The typical microstructure of LPBF-processed W–Ti alloy could be divided into two main regions including W bulk region and W dendrite region with the chemical compositions of W–Ti solid solution, which was caused by the significant difference of melting point between W and Ti. The high microhardness of 731 HV0.2 and compressive performance (σbc = 1719 MPa, δ = 24.7%) were achieved. Compared with pure tungsten samples of our previous work (902 MPa), the compressive strength of W–Ti alloy by LPBF displayed significant improvement of 90%, which could be attributed to the increased densification level and solid solution strengthening mechanism. These findings provided the knowledge of the relationship between laser processing parameters and properties of LPBF-processed W–Ti alloy, further providing reference values applicable for development of W-based alloys by laser additive manufacturing.