Abstract
Fe specimens containing 0.3-0.9 mass% Si were annealed in Pb-Zn melt at 733K. Formation and growth kinetics of Fe-Zn alloy layer on the surfaces of the specimens was examined. A Fe-Zn alloy layer with a continuous and protective structure was formed in the melt containing less than 40 mass% Zn. The Fe-Zn alloy layer consists of δ1 and ζ phases, its thickness increases with annealing time according to a parabolic rate law. A fragmentary δ1 layer composed of small discrete δ1 crystals embedded in a matrix of the η phase was formed in the melt containing more than 40 mass% Zn. Although a coherent δ1 layer exists between the fragmentary δ1 layer and the substrate of the specimen, its thickness is very thin. The Pb-Zn layer on the surface of the alloy layer can be removed if the specimen is immersed in pure Zn melt, but the fragmentary δ1 layer is formed after a short time immersion even though the Fe-Zn alloy layer with the continuous and protective structure previously exists on the surface of the specimen.
