Hybrid manufacturing by 3D printing: A facile route to fabricate high-performance complex parts of low-fluidity high-entropy alloys

For low-fluidity alloys such as TiNb-rich high-entropy alloys, casting parts with complex geometry normally encounter the forming problems like incomplete filling, shrinkage cavities and porosity. Additive manufacturing (AM) is suitable for fabricating those complex parts. However, for the regular portion of a complex part such as the disc of an impeller, AM is not a cost-optimal choice. This work proposes a facile route to fabricate high-performance parts with complex geometry, in which the portion with regular geometry is cast whereas the complex portion that requires high performance is additively manufactured. The results show that the failure always occurs in the cast portion of the hybrid manufactured sample rather than at the interface between the AM portion and the cast one. The strong interfacial bonding is quite different from the welding joint which is commonly the weak link. Moreover, compared with the cast portion with coarse equiaxed grains, the equiaxed fine-grained AM portion exhibits higher strength without sacrificing ductility. Hybrid manufacturing does not introduce weakness, but rather can strengthen the targeted portion by a reasonable structural design.