Application of grazing incidence wide-angle X-ray scattering to characterise mechanically plated coatings

Post-mechanical plating heat treatment on zinc and zinc-tin coatings resulted in the formation of an iron-zinc-rich intermetallic layer between the substrate and the coatings, while the outer coating layer became tin-rich in the case of heat-treated zinc-tin coatings. The novel use of grazing incidence wide-angle X-ray scattering detected not only zeta-FeZn13, delta 1p-Fe13Zn126 and delta 1k-FeZn6.67 phases but also Gamma 1-Fe11Zn40 and Gamma-Fe4Zn9 phases due to the higher resolution and signal-to-noise ratio of synchrotron X-ray diffraction (XRD) compared to traditional XRD. Microstructure evolution models during the heat treatment of mechanically plated zinc and zinc-tin coatings are proposed. The formation of iron-zinc intermetallic phases was in the sequence of zeta-FeZn13, delta 1p-FeZn10, delta 1k-FeZn7, Gamma-Fe3Zn10 and Gamma 1-Fe5Zn21 phases when the heat treatment duration increased.