Novel precipitate–microstructural architecture developed in the fabrication of solid copper components by additive manufacturing using electron beam melting

The fabrication of Cu components by additive manufacturing using electron beam melting (EBM) from low-purity, atomized Cu powder containing a high density of Cu2O precipitates exhibits a novel example of precipitate–dislocation architecture. Such architectures are seen by optical metallography, and scanning and transmission electron microscopy, to consist generally of equiaxed precipitate–dislocation cell-like arrays (1–3 μm) in the horizontal reference plane perpendicular to the build direction with elongated or columnar-like arrays extending from ∼12 to >60 μm in length and corresponding spatial dimensions of 1–3 μm. The hardnesses for these architectures ranged from ∼HV 83 to 88, in contrast to the original Cu powder microindentation hardness of HV 72 and the commercial Cu base plate hardness of HV 57. These observations illustrate the prospect for creating some form of controlled microstructural architecture by EBM parameter alternation or optimization.

► In this study we have fabricated copper monoliths by electron beam melting.
► We observe columnar Cu2O (Cuprite) precipitates which extend in the build direction.
► These precipitates are interconnected by dislocations and exhibit 2 μm spatial arrays.
► These spatial columns of precipitates and elongated copper grains occur by a directional solidification process.