MICROSTRUCTURE AND GROWTH KINETICS OF ALLOY LAYER IN THE Fe- Zn SYSTEM

From the moment of immersion, the reaction between molten zinc and solid iron starts forming intermetallic phases. This diffusion controlled process is responsible for the final phase composition of zinc coating. Several samples were created by hot-dipping at various immersion times at T = 723 K (450 degrees C). Dipping times were divided into two groups. Short term immersion for studying early stages of phase nucleation and growth and long term immersion for observing later phase change and quasi-equilibrium states. For characterization of phases present an EDX was used to determine iron concentration across the alloy layer. After metallographic preparation each phase layer thickness was carefully measured all along with the total thickness of the alloy layer. Results of these measurements were compared with the latest findings. Keeping the same conditions of immersion and only changing the duration allowed us to estimate nucleation and growth kinetics of the layer forming process.