Effects of Cu Addition on the Microstructures and Properties of WC-12Co Cemented Carbides Additively Manufactured by Laser Powder-Bed Fusion

The preparation of WC-Co cemented carbides by laser-based additive manufacturing (AM) is challenging, as the resulting products are often plagued by crack and pore defects. In this study, Cu-doped WC-12Co cemented carbides were successfully prepared by laser powder-bed fusion (LPBF). The effects of LPBF parameters and Cu doping on the defects, microstructures, and properties of the WC-12Co cemented carbides were analyzed. It was found that the laser scanning speed had a significant effect on the density of the AM specimen, and that the doping of Cu reduced cracks. A slow scanning speed and small amounts of Cu dopant were found to be conducive to the manufacturing of highly dense WC-12Co-xCu AM specimens. The microstructure of LPBF-prepared WC-12Co-xCu cemented carbides contained alternating coarse- and fine-grained regions. Cu doping reduced the size of the W2C phase, caused the W1-xC phase to disappear, significantly reduced grain sizes, and increased the number of low-angle grain boundaries. Cu doping also reduced microhardness; the microhardness of the WC-12Co-3Cu specimen that was prepared using a laser scanning speed of 500 mm/s was 25.45% lower than that of WC-12Co. However, compressive strength was significantly increased by Cu doping; the compressive strength of the WC-12Co-3C specimen was 36.20% higher than that of WC-12Co. The wetting angle initially increased (up to a peak of 154 degrees with 2 wt.% Cu) and then decreased with increasing Cu content. The maximum wetting angle was similar to 5.7 times that of the undoped AM specimen.