Toward Control of Microstructure in Microscale Additive Manufacturing of Copper Using Localized Electrodeposition

The progress in microscale additive manufacturing (mu-AM) of metals requires engineering of the microstructure for various functional applications. In particular, achieving in situ control over the microstructure during 3D printing is critical to eliminate the need for post-processing and annealing. Recent reports have demonstrated the possibility of electrochemical mu-AM of nanotwinned metals, in which the presence of parallel arrays of twin boundaries (TBs) are known to enhance mechanical and electrical properties. For the first time, the authors report that the microstructure of metals printed using the microscale localized pulsed electrodeposition (L-PED) process can be controlled in situ during 3D-printing. In particular, the authors show that through electrochemical process parameters the density and the orientation of the TBs, as well as the grain size can be controlled. The results of the in situ SEM microcompression experiments on directly 3D-printed micro-pillars show that such control over microstructure directly correlates with the mechanical properties of the printed metal.