Mechanical Properties of Nanocrystalline Nominally Multilayered Hexagonal Cobalt Electrodeposit

The microstructure and mechanical properties of electrodeposited nanocrystalline cobalt were investigated and compared to cobalt electrodeposits produced under waveforms that would result in a nominal multilayered material by alternating electrodeposition conditions in the same electrolytic solution.;All sample types were of the hexagonal crystal structure and a preferred orientation was prominent with the introduction of nominal multilayers, in which the basal plane preferentially was oriented parallel to the surface of the deposit. Transmission electron microscopy was used to compare the starting microstructure and post-failure microstructure of cobalt electrodeposits. Tensile tests were performed at a strain rate of 5 x 10-4 s -1 and microhardness tests were performed under a 100g load. The average hardness, yield, ultimate tensile and fracture strengths increased when the electrodeposited cobalt followed a nominal multilayered pulse train. Tensile elongation for cobalt electrodeposits with 100 nm nominal layer thicknesses are more than twice that observed for monolithic cobalt.