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.

Research highlights▶ Novel in situ WC-based hardmetals were prepared by Selective Laser Melting. ▶ Laser processed hardmetals had high densification rate and microhardness. ▶ Interesting evolutions of microstructures of in situ phases were disclosed. ▶ Metallurgical mechanisms behind microstructural developments were proposed.