Influence of Ni content on microstructure of W–Ni alloy produced by selective laser melting

• Different Ni content W–Ni parts were produced via selective laser melting.
• The influence of Ni content on the microstructure evolution was studied.
• The micro hardness variation of as-built parts was investigated methodically.
• The forming mechanism on SLM of W–Ni particles was studied and explained.

W–Ni alloy parts were produced with selective laser melting (SLM) and the influence of the Ni content on the microstructure evolution and microhardness was investigated methodically. The resultant microstructure of the SLM specimens with a Ni content of 10 wt.%, 20 wt.% and 40 wt.% exhibited bar-shaped structures, dendrites and honeycomb structures respectively. It was found that a higher Ni content decreased the melt viscosity and increased the densities of W–Ni parts. The microhardness decreased on the other hand with increasing Ni content. The microstructure formed in the SLM process was characterized by a mixture of typical liquid phase sintering (LPS) microstructure and W dendritic structure. This revealed that the forming mechanism of the SLM process on W–Ni particles was a combination of LPS and partial melting of W particles. The microstructure showed that SLM process improved the bonding ability of the powder particles and therefore enhancing the mechanical properties.