Radiogenic silicon precipitates in neutron irradiated aluminum

A theory of precipitation of radiogenic Si in Al is developed. The aim of this study is to predict quantitatively the variation of microstructural parameters such as precipitates number and sizes dependently on irradiation parameters. Analogy with deposition of thin films and formation of silver halides is discussed. A model for the precipitation of radiogenic Si in Al is developed on the basis of the theory of Ostwald-ripening in precipitation processes with constant rate addition of monomers. The model predicts that after the precipitation process enters the 'late' stage, the number of precipitates depends only on the ratio between the thermal and fast neutron fluxes but not on the absolute values of flux and fluence. A quantitative interpretation of the spectral effect, suggested by Farrell [Mater. Res. Soc. Symp. Proc. 373 (1995) 165] is given. The predictions of the model are compared with experimental results.