Annealing behavior of nickel electrodeposited from sulfamate bath at different temperatures

Nickel electrodeposits oil copper plates were prepared from a sulfamate bat h at a current density of 200A m(-2). The bath temperature was vaned from 3 0 to 60 degreesC at increments of 10 degreesC. The recrystallization behavi or was studied via the microstructural characterization of Ni deposits afte r 1 h of annealing at temperatures ranging from 200 to 600 degreesC at incr ements of 100 degreesC. In addition, optical metallography and cross-sectio nal transmission electron microscopy (TEM) were used to characterize the mi crostructure of Ni deposits. The texture of Ni deposit was determined by co nventional X-ray diffraction method. Ni deposited at 50 degreesC exhibited a weak [110] texture, whereas Ni plated at temperatures lower than 40 degre esC displayed a strong [100] texture. The microstructural and hardness chan ges of Ni deposits upon annealing differed for the deposits with different textures. After annealing at temperatures higher than 300 degreesC, the rec rystallized nuclei were observed on the [110]-oriented deposits, which cont ained high-density dislocations and numerous twins. An equiaxed grain struc ture was observed Tor the Ni deposits annealed at 600 degreesC. Conversely, for [100]-oriented deposits, which contained less lattice defects, the rec overy and grain growth prevailed in the absence of pronounced recrystalliza tion after 1 h of annealing at temperatures up to 600 degreesC, when the [1 00]-oriented deposits still retained their well-defined columnar grain stru cture. The different annealing behaviors associated with the distinct textu red Ni deposits could be explained by their different lattice defects. That is, the population density of twins associated with the as-deposited Ni ma rkedly affected the feasibility of the formation of twin-free recrystallize d nuclei.