Sources of variability in grain boundary segregation

Abstract

This paper considers the sources of variability in segregation to random high angle grain boundaries. The variation in segregation to most grain boundaries is within ±30% of an average value. However, the composition of some boundaries is even farther away from the average. Although deviation in fracture path, bulk chemical inhomogeneities, and a lack of equilibrium can contribute to the variation, analysis of the data clearly shows that differences in grain boundary structure must play a role. The cause of the relationship between structure and segregation is discussed in terms of chemical bonds that are formed between the segregant and the metal atoms comprising the boundary. Finally, it is shown that variation in segregation in a single boundary is not as great as the variation among grain boundaries.