Bubble Formation in Zr Alloys under Heavy Ion Implantation

We report here the results of a study conducted to examine the effect of Kr ion irradiation on bubble formation in Zr alloys. We used the H?EM/Tandem facility at Argonne National Laboratory to irradiate several Zr alloys, including Zircaloy-2 and k d o y 4 , at temperatures from 300 to 800 C and to doses up to 2 x 10'6ion.cm-2. Both in-situ irradiation of thin foils as well as irradiation of bulk samples with an ion implanter were used in this study. For the thin foil irradiations, a distribution of small bubbles in the range of 30-100 8, was found, at all temperatures with the exception of the Cr-rich Valloy where bubbles of 130 A were found. The irradiation of bulk samples at high temperature (700-800 C) produced large faceted bubbles (up to 300 A) after irradiation to 2 x 1OI6 ion.cm-'. The results are examined in the context of existing models for bubble formation and growth in other metals.