Radiation Effects in Metals

After thermalization, the defects begin to migrate, recombine, cluster, or precipitate provided the temperature is high enough to activate the motion of point defects. The various possible processes depend on defect concentration and their spatial distribution as well as on defect mobility and their interaction energies. As in non-metallic crystals, internal and external surfaces act as sinks for at least a part of the radiation induced defects in metals. 

The first two terms in the bracket correspond to the customary chemical free energy density and the gradient energy respectively. The third term takes into account the ballistic flux. D is the Darken interdiffusion coefficient (Eqn. (4.78)), but adapted to the radiation induced increased defect concentration of the alloy. 

An interesting result has been obtained after the introduction of the regular solution model [C. Wagner (1952)] into Eqn. (13.12). The free energy f(NA, T)m of the alloy under irradiation equals the free energy / of the alloy without irradiation but at an increased temperature, that is, f(NA, T)kl = f(NA, T+ AT). AT is found to be 

Equation (13.13) suggests that the steady state of the alloy under irradiation is the same as that of the non-irradiated alloy at T+AT. Explicitly, one obtains 

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