Effects of hot-dip galvanizing and aluminizing on interfacial microstructures and mechanical properties of aluminum/iron bimetallic composites

In this paper, the aluminum/iron bimetallic composites were successfully fabricated using ZL114A alloy and gray cast iron by hot-dip galvanizing and aluminizing method, and the effects of the hot-dip galvanizing and aluminizing on interfacial microstructures and mechanical properties of the aluminum/iron bimetallic composites were investigated. Without the application of the hot-dip galvanizing and aluminizing, the gaps and oxide films were formed at the interface between the aluminum and the iron, resulting in a poor mechanical bonding without a reaction layer between the aluminum and the iron. In the case of the hot-dip galvanizing and aluminizing, a relatively uniform and compact reaction layer that mainly consisted of Fe2Al5, τ10-Al9Fe4Si3, FeAl3, τ5-Al8Fe2Si and τ6-Al4.5FeSi intermetallic compounds was formed between the aluminum and the iron. The curved interface had a thicker reaction layer up to about 53 μm compared to the straight interface with an average thickness of approximately 25 μm. The average nano-hardnesses of the straight and curved interfaces between the aluminum and the iron reached respectively 10.79 and 10.49 GPa, which were obviously higher than those of the iron and aluminum base metals, especially the aluminum base.