Effect of Processing Parameters on the Anisotropic Properties of 93W-5Ni-2Fe Alloys Fabricated via Laser Powder Bed Fusion

It can be highly challenging to manufacture W-Ni-Fe alloys with excellent performance using laser powder bed fusion (LPBF) technology. Unlike previous research, this paper examines how processing parameters affect the anisotropic properties of the LPBF tungsten alloys across a wider range of conditions. A 93W-5Ni-2Fe alloy with a density exceeding 98% was achieved within a laser power range of 300–325 W. Densification can be notably enhanced by decreasing the scanning speed and hatch distance. Two density peaks appeared in the VED range of 417–541 J/mm³ and 833–972 J/mm³, which were attributed to the difference in scanning speed or hatch distance. The microstructure of the LPBF tungsten alloy in the horizontal and vertical sections showed dense equiaxed grains and large columnar grains, respectively. The formation of columnar grains was due to the layer-by-layer deposition of the molten pool during the LPBF process, resulting in two different crack patterns, cross-, and vertical cracks, on the horizontal and vertical sections. The microhardness on the vertical section of the LPBF tungsten alloy showed greater volatility, which was attributed to the thermal gradient in the printing direction. The laser power (300–400 W) did not seem to have a positive effect on the microhardness of the LPBF tungsten alloy. The microhardness on the horizontal and vertical sections reached the maximum values at VED of 417 J/mm³, 618, and 640 HV, respectively. The anisotropy of the microhardness of the LPBF tungsten alloy was quantitatively analyzed, and the difference in microhardness between the horizontal and vertical sections was within 22%. This study serves as a valuable reference for the laser manufacturing of tungsten alloys.