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

Abstract

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 ζ-FeZn13, δ1p-Fe13Zn126 and δ1k-FeZn6.67 phases but also Γ1-Fe11Zn40 and Γ-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 ζ-FeZn13, δ1p-FeZn10, δ1k-FeZn7, Γ-Fe3Zn10 and Γ1-Fe5Zn21 phases when the heat treatment duration increased.