Zn–Fe multilayered alloy coatings produced by electrodeposition

Abstract

Zn–Fe multilayered alloy coatings were deposited on mild steel substrates using the dual bath electrodeposition technique. The produced coatings consisted of alternate Zn–1 wt% Fe and Zn–10 wt% Fe alloy sub-layers. Their periodicity length (total thickness of two adjacent alternate sub-layers) ranged between 2 and 8 μm. The surface and the cross-sectional morphology of those coatings were studied with the aid of a metallurgical microscope and a scanning electron microscope. The crystal structure of the electrodeposited multilayered coatings was investigated using an X-ray diffractometer. The Zn–1 wt% Fe and Zn–10 wt% Fe alloy sub-layers consisted of two phases: the η-phase (Zn–Fe solid solution) and the δ1-phase (intermetallic FeZn7). A microhardness tester equipped with a Vickers intender was used to examine the microhardness of the produced coatings. It was found that the microhardness increased with the decrease of periodicity length, following a modified Hall–Petch relationship.