Segregation to boundaries and interfaces in solids

The basic principles of equilibrium (ES) and nonequilibrium segregation (NES) to boundaries and interfaces in solids as a function of heat treatment are reviewed. Various models used to describe the thermodynamics and kinetics of both processes are outlined and an attempt is made to emphasise the relative merits of each of the models. The importance of vacancy-driven effects in this kind of segregation is stressed. Experimental verification of the models is sought through a discussion of the amassed data on segregation. Equilibrium segregation and NES are treated in turn and a critical appraisal is made of the models in the light of experimental results. The experimental section emphasises the need for much greater investment currently because the only techniques capable of measuring the fine scale segregation effects being considered are sophisticated and expensive methods like field emission gun scanning electron microscopy, Auger electron spectroscopy, and atom probe field ion microscopy. Radiation induced segregation is described. The importance of the strong interstitial binding with impurities in this mechanism is mentioned. The results of various models proposed are compared with experimental findings and the relative advantages of the various models are discussed. Finally, there is a short section on high strain rate induced NES. (C) 1996 The Institute of Materials and ASM International.