NEEP 541 – Diffusion Fall 2003 Jake Blanchard

Outline Diffusion of point defects Mechanisms Vacancy Interstitial Etc.

Diffusion of Defects Defect motion is the key to many aspects of radiation damage The motion allows clustering, leading to larger defects that are better able to affect macroscopic properties Defect diffusion can generally be described by Fick’s law

Fick’s Law

Fick’s Law g=geometry factor =jump frequency G=free energy H=enthalpy S=entropy

Diffusion Mechanisms There are many ways for defects to diffuse Vacancy Direct interstitial Indirect interstitial Kick-out Frank-Turnbull other

Vacancy

Direct Interstitial

Indirect interstitial

Kick-Out

Frank-Turnbull

Direct Exchange Other similar mechanisms exist