Enhanced tensile ductility in an electrodeposited nanocrystalline Ni

A sheet of fully dense nanocrystalline (nc) Ni with a thickness of 350 μm was obtained by a direct-current electrodeposition method. The nc Ni has an average grain size of 40 nm and an evident {200} texture as revealed by X-ray diffraction analysis. TEM observations show that the microstructure of the nc Ni consists of the grain clusters of about 150-300 nm surrounding by nano-grains of about 10-20 nm. Moreover, the clusters are also composed of the nano-grains of about 30-50 nm possessing the small misorientation angles. The room temperature tensile test performed at a strain rate of 1.04×10^-3s^-1indicates that the nc Ni has a combination of high tensile strength of 1220 MPa and enhanced elongation to failure of 7.2%. The optimized mechanical properties of our nc Ni is discussed by connected with its special micro-structures.