Interfacial Layer Formation during Hot Dip Galfan Alloy

Galfan alloy coatings were prepared by reduction method with different hot-dip time. SEM was used to observe the microstructure of Galfan coating and EDS, XRD and TEM were used to analyse the formation of interfacial layer as a function of hot-dip time. The results show that the interfacial layer consists of two layers, and the microstructure is loose grains. The grain changes from equiaxed into sheet or strip as the reaction time increases. The interfacial layer contains \mathrmFeAl_3 and \mathrmFe_2 \mathrmAl_5 \mathrmZn_x. \mathrmFe_2 \mathrmAl_5 has a orientation relationship of (0 \overline2 \overline1)_\mathrmFA / /(110)_\mathrmFe and 02 \overline4_\mathrmFA / /0 \overline1 \overline1_\mathrmFe with Fe substrate. During initial immersion phase, \mathrmFeAl_3 is preferentially formed on the substrate. As the dip time increases, \mathrmFe_2 \mathrmAl_5 appears, and the amount of \mathrmFe_2 \mathrmAl_5 increases.