The banded structure of Ni-P electrodeposits

The banded structure observed in metallographically polished and etched cross sections of Ni-P electrodeposits consisting of alternate dark and light layers parallel to the surface was investigated. The dark bands were attributed to a galvanic attack by the etchant at locations where the phosphorus content of the deposit changed relatively abruptly with thickness. A mechanism for the development of the compositional changes is proposed. Pulsed plating was found to eliminate the banded structure, but had little effect on the fracture strength and ductility.