Zinc alloy offers superior sacrificial protection to steel as the alloy dissolves more slowly than pure zinc.
The degree of protection and the rate of dissolution depend on the alloying metal and its composition. In
this work, the physico-chemical characterization of zinc–nickel electrodeposits obtained from an alkaline
bath is carried out and a description of the structural and thermodynamic properties of these alloys is
proposed.
Contrary to the common acceptance, XRD spectra and DSC thermal analysis show that the electrodeposited
c alloy has to be regarded as a metastable phase, whose atomic arrangement is different from
that of the equilibrium c intermetallic compound. A model for atomic distribution in the electrodeposited
alloy is proposed.
The Gibbs free-energy function for the electrodeposited phase has been evaluated and the metastable
boundaries of the single-phase and two-phase fields have been calculated. Reasonable agreement is
found with experimental values reported in the literature for Zn–Ni coatings with different composition