TEMPERATURE-DEPENDENCE OF BUBBLE STRUCTURE IN 316L-STAINLESS-STEEL IRRADIATED WITH 2.5 MEV HE IONS

In this work, specimens of 316L stainless steel were implanted with 2. 5 MeV He+ ions at constant temperatures of 25 degrees C, 200 degrees C , 300 degrees C, 400 degrees C, 500 degrees C, 550 degrees C, and step -wise variant temperatures of 25 degrees C/600 degrees C and 300 degre es C/550 degrees C, respectively. The dose and dose rate were 2.5 x 10 (21) He ion/m(2) and 3.2-3.8 x 10(16)He ion/m(2)/s for each implantati on. Bubble structures were investigated with creels-section transmissi on electron microscopy (XTEM). The temperature dependence of the measu red number density and mean size of bubbles exhibited two distinctly d ifferent regimes with a transition occurring at 300-400 degrees C. The apparent activation energies suggest that bubble formation is control led by diffusion of He atoms or He clusters in the high temperature re gime, and by an athermal process in the low temperature regime. Cold w orking of the material had observable effects on bubble formation only in the high temperature regime. Under the varying temperature conditi ons, bubble formation was influenced strongly by the temperature of th e first implantation, even if its dose was low. (C) 1998 Elsevier Scie nce B.V. All rights reserved.