Thursday, 4 October 2018: 08:40
Universal 10 (Expo Center)
Microstructure of a metal determines its properties. A major effort in the field of additive manufacturing (AM) of metals is
controlling and predicting the microstructure. Nanotwinned (nt)-metals exhibit superior mechanical and electrical properties compared to their coarse-grained and nano-grained counterparts. nt-metals have a unique microstructure with grains that contain a high density of layered nanoscale twins divided by coherent twin boundaries (TBs). These metals often show higher strength and ductility compared to their nanocrystalline counterpart, since TBs can effectively block dislocation motion. These metals show more resistance to electromigration, which is a common problem for metals at the nano/ microscale. nt-metals in film and bulk forms are obtained using physical and chemical processes including pulsed electrodeposition (PED), plastic deformation, recrystallization, phase transformation, and sputter deposition. However, currently, there is no process for 3D printing (AM) of nt-metals. Given their unique properties, it is desirable to establish an AM process for nt-metals. We developed a new process for 3D printing of nt-metals, termed localized PED (L-PED). We demonstrate microscale 3D printing of nt-Cu with high density of coherent TBs using this process. This cost-effective process, which is performed at ambient environment, enables direct printing of 3D microscale structures of pure metals with nanoscale twins. The 3D printed nt-Cu is fully dense, with low to none impurities, and low microstructural defects, and without obvious interface between printed layers, which overall result in good mechanical and electrical properties, without any postprocessing steps.
controlling and predicting the microstructure. Nanotwinned (nt)-metals exhibit superior mechanical and electrical properties compared to their coarse-grained and nano-grained counterparts. nt-metals have a unique microstructure with grains that contain a high density of layered nanoscale twins divided by coherent twin boundaries (TBs). These metals often show higher strength and ductility compared to their nanocrystalline counterpart, since TBs can effectively block dislocation motion. These metals show more resistance to electromigration, which is a common problem for metals at the nano/ microscale. nt-metals in film and bulk forms are obtained using physical and chemical processes including pulsed electrodeposition (PED), plastic deformation, recrystallization, phase transformation, and sputter deposition. However, currently, there is no process for 3D printing (AM) of nt-metals. Given their unique properties, it is desirable to establish an AM process for nt-metals. We developed a new process for 3D printing of nt-metals, termed localized PED (L-PED). We demonstrate microscale 3D printing of nt-Cu with high density of coherent TBs using this process. This cost-effective process, which is performed at ambient environment, enables direct printing of 3D microscale structures of pure metals with nanoscale twins. The 3D printed nt-Cu is fully dense, with low to none impurities, and low microstructural defects, and without obvious interface between printed layers, which overall result in good mechanical and electrical properties, without any postprocessing steps.