17Nanocrystalline Zn-Ni alloys were proposed from a new developed 18 5,5'-dimethylhydantoin (DMH)-based bath as replacement of Zn and Cd coatings due 19 to their excellent corrosion resistance and environmental friendly properties. However, 20 the mechanism of better corrosion performance of Zn-Ni samples compared with Zn 21 and Cd coatings was rare to be investigated. In the present study, the corrosion 22 36 impedance spectra (EIS) confirm the above facts that Zn-Ni alloys have better 37 corrosion resistance than Zn and Cd coatings, which can be used as the best 38 alternative to Zn and Cd coatings. 39