Anisotropy of interfacial segregation: grain boundaries and free surfaces

Solute segregation was measured at both the {013} grain boundary and the (013) free surface of the same sample of an Fe-6at%Si alloy containing traces of P and S at 873 K. Large phosphorus enrichment and silicon depletion characterize the grain boundary segregation whereas no sulfur was detected there. On the other hand, pronounced sulfur segregation was observed at the surface accompanied by weak enrichments of phosphorus and silicon. Qualitative differences between both types of segregation behavior are considered as a generalized anisotropy of interfacial segregation.