Periodic preferential etching of electrodeposited nanocrystalline nickel-iron alloys

This thesis is the first in-depth study of a recently reported type of mesoscale structure in electrodeposited nanocrystalline Ni-Fe alloys, observed as a periodic banded structure in etched cross-sections. To investigate the mesoscale structure, three aspects of banding in these alloys were examined: the first involved characterization of the mesoscale structure in depth in one electrodeposit (Ni-53%Fe) to determine the mechanisms of banding; the second involved the examination of the banded structure in other electrodeposited nanocrystalline Ni-Fe alloys for potential use in nanopatterning applications; the third involved the examination of the thermal stability of the bands. The combined effect of periodic variations in alloy composition and impurities resulted in non-homogeneous corrosion of the alloy. Examination of other Ni-Fe alloys found that the most regular banded structure is in Ni-7.5%Fe. It was also observed that the banded structure in Ni-Fe alloys of high iron content have increased thermal stability.