Diffusion Mechanisms
Vacancy diffusion - involves the interchange of an atom with a neighbouring vacant site
- Depends on concentration of vacancies
- Both self diffusion and impurity diffusion operate by this mechanism (e.g. Cu or Zn in brass)
Interstitial diffusion - involves the migration of impurity atoms from one interstitial site to another
- Generally faster than vacancy diffusion because small, impurity atoms are more mobile (e.g. C, N in steel)