Recovery kinetics in stages IDand IEof irradiated metals—one-dimensional versus three-dimensional interstitial migration

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Abstract
It is shown that at early times t the rate dc/dt of a diffusion-controlled bimolecular reaction A + B → C obeys the relationship dc/dt = - √D/nt cog(ro) provided that the probability g(r0) to find at t = 0 particles A and B at the distance of reaction, r 0, is finite (D = sum of the diffusivities of A and B, c = atomic fraction of A or B, co = value of c at t = 0). Since this result is independent of whether the particles diffuse in one or three dimensions, the observation that the early portion of the recovery stage ID of electron-irradiated copper follows this law cannot be exploited to discriminate between the migration of crowdions or three-dimensionally diffusing interstitials. Computer simulations show that a separation of uncorrelated recovery (Stage IE) from correlated recovery (Stage ID) occurs not only for interstitial migration in three dimensions but also for the migration of a mixture of off-line and on-line crowdions. Henee, a discrimination between the current models of radiation damage in metals based on an analysis of the recovery kinetics in the Stage ID/IE regime appears hardly feasible.