Fick's first law is modified with an additional term df(x)/dx to describe the segregation phenomenon,f(x)is a local,analytical function related to the depth profile at equilibrium.It thus can be determined experim...Fick's first law is modified with an additional term df(x)/dx to describe the segregation phenomenon,f(x)is a local,analytical function related to the depth profile at equilibrium.It thus can be determined experimentally by depth profiling technique.Segregation starting in an initially homogeneous solid is described by an inhomogeneous diffusion equation on the half-infinite domain.Segregation with and without formation of overlayer suggests different boundary conditions.The solution for the Ansatz f(x)=as exp(-x/d_(s))is in perfect agreement with experimental results on sulphur segregation to the surface of titanium.Independent from the detailed kinetics,activation energy can be inferred from the surface concentration evolution under different temperatures.For sulphur segregation in titanium,E_(act)=718 meV/atom.展开更多
基金Supported by the Volkswagen Foundation,Hannover,Germany.
文摘Fick's first law is modified with an additional term df(x)/dx to describe the segregation phenomenon,f(x)is a local,analytical function related to the depth profile at equilibrium.It thus can be determined experimentally by depth profiling technique.Segregation starting in an initially homogeneous solid is described by an inhomogeneous diffusion equation on the half-infinite domain.Segregation with and without formation of overlayer suggests different boundary conditions.The solution for the Ansatz f(x)=as exp(-x/d_(s))is in perfect agreement with experimental results on sulphur segregation to the surface of titanium.Independent from the detailed kinetics,activation energy can be inferred from the surface concentration evolution under different temperatures.For sulphur segregation in titanium,E_(act)=718 meV/atom.
文摘1 Introduction Today’s business process management (BPM)systems have evolved to provide rich and sophisticated tooling and runtime support for subject
