Study Of Microstructure Of The Hot-dipped Aluminum Coating On Steel And Effect Of Rare Earth (La)

Hot-dip aluminizing is a technology that integrates with strengthening, protection and decoration on the surface of iron and steel. It can intensify a lot of properties of iron and steel in corrosion resistance, resistance to heat and oxidation resistance at high temperature, decrease the economic loss by corrosion and abrasion, prolong the life of ferrous products greatly and bring good benefits. In this paper, effect of rare earth elements on kinetics of hot dip aluminizing was studied, the microstructure of hot dip aluminizing was studied by TEM. Some performance of hot dip aluminizing was explained through the microstructure.The cross section microstructure and composition of coating hot-dipped with Aluminum were analyzed by TEM . The results show that the microstructure of coating are respectively amorphous, nano-crystalline,Fe-2Al₅,FeAl₂,FeAl,Fe3Al,AlFe3C0.5 from surface to inner coating. There are spinodal decomposition structures in amorphous, nano-crystalline , Fe-2Al₅ and FeAl₂ . The wavelengths of spinodal decomposition at initial stages were analysed by the theory of static lattice waves. There wavelengths were gradually augment from 0.63nm to 10.6nm from surface to inner coating. there are not spinodal decomposition structures in FeAl,Fe3Al,AlFe3C0.5. The Al₄C₃ phases in hot-dipped aluminum steel were club-shaped and approximately rounded. The Al₄C₃ phases existed in hot-dipped aluminum steel as twins. And the 180o secondary rotary twins with (003)as twin surface ,...