Strong and Ductile Electroplated Heterogeneous Bulk Nanostructured Nickel

Porosity-free bulk nanostructured nickel cannot be fabricated by conventional electroplating due to hydrogen bubbling at the cathode. Here, we developed a cathode-rotating electroplating technique to remove the bubbles in order to obtain millimeter-scale nanostructured nickel rods with low porosity. The grain sizes ranged from 20 to 300 nm. The range produced by the new technique was broader than those that have been reported. The heterogeneous microstructure contributed to high work hardening rate, yield strength, and ductility of the rods in tension. The ductility was larger than electroplated thin nickel film with comparable ultimate strength in the literature. Dislocations accumulated at pre-existing twins, grain boundaries, and at the grain interior mediated the plastic deformation of the rods.