Enhanced hardness and toughness in WC/W2C-Ni-Cu composites fabricated by selective laser melting

Dual-grain WC/W2C-Cu-Ni composites were fabricated by selective laser melting using a mixture of Ni-coated WC-W2C and CuNi powders. The phase composition and microstructure of the processed composites were investigated by X-ray diffraction, scanning electron microscopy, electron backscattered diffraction and transmission electron microscopy techniques. The results revealed that the microstructure of composites was consisting of both partially melted WC-W2C particles and nano-WC grains evenly distributed in the CuNi binder phase. The existence of WC1-x phase was detected between nano-WC and CuNi phases. An interface formed between protruding parts, existing around the partially melted WC-W2C particle, and CuNi resulted in the increase of the contact area and bonding strength between the partially melted WC-W2C particles and the matrix. The mechanical properties (hardness, bending strength and toughness) of the composites processed in this research were investigated and compared to those of parts fabricated by pressureless infiltration. The dual-grain structure of the composites enhanced their mechanical properties compared to those of traditional WC composites processed by a pressureless infiltration method.