Microstructure characteristics and formation mechanisms of in situ WC cemented carbide based hardmetals prepared by selective laser melting

Selective Laser Melting (SLM) of W-Ni-graphite powder mixture was performed to prepare in situ WC/Ni2W4C(M6C) cemented carbide based hardmetals. The WC phase was developed via a multi-laminated growth mechanism and it experienced block-shaped-triangle-elliptical morphological change on decreasing the linear energy density. The amount of the formed M6C increased and its structure changed from a granular form to a ring shape at a lower laser energy input. SLM-processed cemented carbide based hardmetals possessed a high densification level of 96.3% and a maximum microhardness of 1870.9 HV0.1. The dominant metallurgical mechanisms behind the microstructural developments were also proposed.