An enhanced diffusion of 59Fe radiotracers in relaxed amorphous samples, under 400keV proton irradiation, was investigated as a function of the duration and temperature of diffusion and of the proton flux. It was found that steady-state conditions were always achieved, that the diffusivity enhancement was proportional to the proton flux, that 59Fe diffusivity obeyed Arrhenius laws with or without irradiation, and that irradiation increased the pre-exponential factor but did not change the diffusion enthalpy. The results were explained in terms of a direct diffusion mechanism whose operation was restricted to unrelaxed spots that were embedded in an otherwise relaxed amorphous matrix. The only effect upon diffusion of low energy-transferring irradiation was an increase in the unrelaxed-spot concentration, to above its thermodynamic equilibrium value in the absence of irradiation.

P.Scharwächter, W.Frank, H.Kronmüller: Zeitschrift für Metallkunde, 1996, 87[11], 892-7