Nanocrystalline electrodeposited Ni: microstructure and tensile properties

The microstructure of commercially available nanocrystalline (nc) electroplated Ni foils is studied by means of Xray diffraction and transmission electron microscopy. It is shown that the microstructure is inhomogeneous and batch-dependent. Tensile properties at strain rates between 10(-5) and 10(3) s(-1) are studied and compared with the results of coarse-grained Ni. Data on strength, strain-rate sensitivity and work hardening are presented. At the highest strain rates, shear banding with local grain growth is observed in the nc structure. It is also suggested that the differences found in nc Ni for 3 and 20 mm tensile specimens are the size effects related to the inhomogeneous microstructure. (K) 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.