The effect of flux on ion irradiation-enhanced precipitation in AISI-316L: an in-situ TEM study

Thin foils of AISI 316L stainless steel were irradiated in-situ in a transmission electron microscope (TEM) with 325 keV Xe ions at 550 °C at three different fluxes to study flux effects. The kinetics of the radiation-enhanced precipitation (REP) and the evolution of the precipitates were found to be correlated with the irradiation flux. At lower fluxes (1 and 2 × 10 ¹² ions∙cm ⁻²∙s ⁻¹), cascade mixing played an important role in the accumulation of point defects within the austenite matrix, facilitating the formation of clusters which act as sinks for heterogeneous nucleation of precipitates with high areal density. At the highest flux (4 × 10 ¹² ions∙cm ⁻²∙s ⁻¹) the cascade mixing favours the recombination of vacancies and interstitials which supresses the growth of existing precipitates beyond a certain total damage level. The results agree with a previous radiation-enhanced precipitation model proposed by Wiedersich, Okamoto and Lam and further studied by Bruemmer, but a small modification is proposed when the flux is close to the vacancy-interstitial recombination limit.