On the relationship between the entropy and enthalpy of interfacial segregation

The general relationship between the excess entropy and enthalpy of segregation is elucidated in terms of basic thermodynamical principles applied to the bulk-interface equilibrium. The linearity reported in several studies of different grain boundary or surface orientations in alloys is accounted for in case at some temperature, the excess entropy varies much more strongly than the ideal solution configurational contribution to the segregation entropy. The theoretical analysis done for monolayer segregation (e.g., of non-metal impurity), shows that the linear relationship can be explicitly quantified by means of a quasi-isotropic interfacial segregation level and the corresponding temperature, and without introducing significant error in case of multilayer segregation