Interstitial migration energy

Self-Diffusion by the Interstitialcy Mechanism. If their formation energy is not too large, the equilibrium population of self-interstitials may be large enough to contribute to the self-diffusivity. In this case, the self-diffusivity is similar to that for self-diffusion via the vacancy mechanism (Eq. 8.19) with the vacancy formation and migration energies replaced by corresponding self-interstitial quantities. The... 

APB converts these into <121> shear planes. It would also obviously be desirable to calculate the activation energies for interstitial migration down the APBs. This is at present beyond the scope of our calculations, although developments in the field may soon render such calculations feasible. 

In polyclusters, atoms can diffuse on vacant cavities, viz., regular vacancies, interstitial holes in the LRC bulk, and partial vacancies or vacant coincident sites at the boundaries. Since the formation and migration energies of regular... 

The temperature dependence of the diffusion coefficient will depend on the diffusion mechanism. If diffusion occurs interstitially, the temperature dependence of D will include only the migration energy term, Ai/, since the probability of the site adjacent to an interstitial atom being vacant is 1.0. 

The same arguments apply to interstitials. In pure metals of simple (f.c.c. or b.c.c.) crystal structure, the structure and properties of interstitials are well-known for example, in many f.c.c. metals, it consists of a dumbbell oriented in a <1 OOHype direction, with a large formation energy (several eV) and a small migration energy (typically 0.2 eV). In intermetallic compounds, the structure of interstitials is generally not known in some cases, several types of complex defects occur... 

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