Potentiostatic versus galvanostatic electrodeposition of nanocrystalline Al-Mg alloy powders

Nanocrystalline supersaturated dendritic Al-Mg powders were electrodeposited using potentiostatic and galvanostatic techniques under equal-charge conditions. In potentiostatic deposition morphology depended on applied potential: featherlike at lower and globular at higher potentials. Galvanostatic deposits yielded both morphologies at any current density. Morphological evolution was observed in galvanostatic deposits from featherlike to globular. Independent of deposition technique face-centered cubic Al(+Mg) phase with similar to 7 atom% Mg (featherlike) with/without similar to 20 atom% Mg (smooth globular) composition formed at lower applied/realized potentials (or deposition rates). Higher applied/realized potentials showed hexagonal close packed Mg(+Al) phase with similar to 80 atom% Mg (rough globules) over smooth globules. Potentiostatic and galvanostatic deposits were compared for their morphologies, phases, and compositions.