The depth distribution of void swelling produced by 5 MeV Ni ions

Abstract

Abstract The depth distribution of void swelling has been measured in alloys bombarded with 5 MeV Ni ions. At 625°C there is a 50 nm void-free zone at the surface, and an additional 50 nm zone in which the swelling is reduced due to surface proximity. The observed swelling profiles are compared with predictions based on the calculated displacement profile and earlier swelling data obtained by TEM analysis in the peak damage region or by step height measurements. Analysis of the effects of variation in displacement rate along the ion range, similar to the analysis of Garner and Guthrie, shows that extreme variations of the swelling profile will be produced at bombardment temperatures far removed from the peak swelling temperature. Ignoring displacement rate effects will result in an error of less than 15% if the bombardment temperature is no more than 25°C higher or 50°C lower than the peak swelling temperature, but the error will increase rapidly outside that temperature range. Anomalously high swelling is observed in some alloys in a sub-surface region located 0.1 to 0.3 μm from the surface.