Study Of The Phase Diagram Zn-Fe-Mo System At The Zn-rich Corner And The Determination Of The Liquid Diffusion Coefficient Al In Molten Zn

Continuous galvanizing has a widespread application in modern industry.There are many alloying elements,such as Mn,Cr,Ti,Si,Al and Mo,in high-strength steels. The surface reaction is affected by these alloy elements.When exposed to molten Zn, Fe and Mo dissolve from the substrate and diffuse into the bath.The Zn-Fe-Mo ternary system is important to analyze the alloying elements' role in hot-dip galvanizing.Al is one of the most widely used alloying elements in the hot-dip galvanizing process.To analyze the development of Fe₂Al₅ layer in the hot-dip coatings and the rate-limiting process of the interface reaction,the determination of Al diffusivity in liquid Zn is necessary.This work will improve quality of galvanized products and promoting the development of continuous galvanizing industry.By means of optical microscopy,SEM-EDS analysis and X-ray diffraction,the 450℃isothermal section of the Zn-Fe-Mo system was experimentally determined in the present work.Experimental results show that the 450℃isothermal section of the Zn-Fe-Mo system consists of nine ternary phase regions;Liq.+MoZn₂₂+ζ,δ+MoZn₂₂+MoZn₇,ζ+δ+MoZn₂₂,δ+MoZn₂₂+Mo,δ+Mo+μ,δ+Γ₁+μ,Γ+μ+Γ₁ andΓ+μ+α-Fe.No ternary phase was found.The phase diagram was drew with the experiment data above.By experimental measurements and data analysis,the diffusivity of Al in liquid Zn was determined using liquid diffusion couples at 450℃.Based on the model of the half-infinitude diffusion,the concentration gradient of Al in diffusion coatings was calculated using software written specifically for this research.