Non-equilibrium segregation in metals and alloys

Abstract

The phenomenon of non-equilibrium segregation of solute and impurity atoms at interfaces in quenched materials is defined and the driving force and kinetics of the segregation are shown to differ significantly from those of reversible equilibrium segregation. Large point defect supersaturations are produced during quenching, irradiation and sintering, and both enrichment and depletion of solute atoms at interfaces, associated with the flow of point defects to sinks, have been observed. Some of the quantitative and qualitative experimental data on non-equilibrium segregation are described and the current understanding of the mechanisms and kinetics are summarized. Finally, some of the practical implications of non-equilibrium segregation, in terms of the effects on the deformation, fracture and mechanical properties, corrosion behaviour and structural stabilities of quenched and irradiated metals and alloys, are outlined and possible methods of inhibiting segregation are suggested.