Reactive diffusion between solid Fe and liquid Zn at 723 K

Reactive diffusion between solid Fe and liquid Zn was experimentally examined using Fe/Zn diffusion couples prepared by an immersion technique. Using this technique, a pure iron sheet was immersed in a molten pure Zn bath with a constant temperature of T=723 K (450 degrees C) for various times up to t=7.2x10(3)s (2 h). The microstructure of the cross section of the Fe/Zn diffusion couple was observed by scanning electron microscopy, and the chemical composition of each phase was determined by electron probe microanalysis. Interface concentrations of Fe for the zeta-FeZn13 and delta-FeZn7-10 phases at the zeta/delta interface, c(zeta delta) and c(delta zeta), and for the liquid-Zn (L) phase at the zeta/L interface, c(L zeta), determined from the diffusion couples were found to be extremely higher than the corresponding equilibrium values, especially in the early stage of t<300 s, and the difference gradually decreased during immersion. The deviations from the equilibrium values for the c(zeta delta) and CL were proportional to the interduffusion flux across the; phase layer.