Microstucture evolution and interfacial properties in the Fe–Pb system

Abstract

Fe-rich Fe-Pb alloys were synthesized from elemental powders for studying the grain boundary wetting by the liquid phase and for studying the effect of dispersed insoluble inclusions of a liquid phase on microstructure evolution. From the atomic force microscopy analyses of the grain boundary grooves formed at the sample surface, the grooving mechanisms in pure Fe, Fe in contact with Pb vapor, and Fe in contact with liquid Pb were identified, and the interface diffusion coefficients were determined. It was demonstrated that the wetting of grain boundaries in Fe by liquid Pb is imperfect. For the first time, an anomaly of the surface self-diffusion coefficient of Fe below the Curie temperature was observed (magnetic effect for the surface diffusion). Based on the diffusion coefficients measured, the interaction of moving grain boundaries with the liquid Pb particles was quantitatively analyzed. The theoretically predicted limiting grain size in the Fe-Pb alloy after stagnation of the normal grain growth was in a good agreement with the experimental observations.