Orientation dependence of the surface segregation kinetics in single crystals

Abstract

Experimental results are presented that support an earlier hypothesis that the bulk diffusion near surfaces is orientation dependent. From a literature study, the calculated surface energy of the (110) surface is higher than that of the (111) surface in fcc crystals, which could lead to different values of the bulk vacancy formation energy. This energy term determines the equilibrium bulk vacancy concentration and consequently also the bulk diffusion coefficient. Experimental surface segregation results were obtained for Cu(0.1%Sb) crystals for the said (110) and (111) surfaces using the linear heating method. The results, D110 > D111, confirm the assumptions, and the order of magnitude experimental values of the activation energies are compatible with the calculated surface energies from the literature. Copyright © 1999 John Wiley & Sons, Ltd.