Surface effects and statistical laws of defects in primary radiation damage: Tungsten vs. iron

¹ Department of Physics, University of Helsinki - P.O. Box 43, FI-00014 Finland
² Departamento de Fisica Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante Alicante E-03690, Spain

Received: 16 June 2016
Accepted: 11 August 2016

Abstract

We have investigated the effect of surfaces on the statistics of primary radiation damage, comparing defect production in the bcc metals iron (Fe) and tungsten (W). Through molecular dynamics simulations of collision cascades we show that vacancy as well as interstitial cluster sizes follow scaling laws in both bulk and thin foils in these materials. The slope of the vacancy cluster size distribution in Fe is clearly affected by the surface in thin foil irradiation, while in W mainly the overall frequency is affected. Furthermore, the slopes of the power law distributions in bulk Fe are markedly different from those in W. The distinct behaviour of the statistical distributions uncovers different defect production mechanisms effective in the two materials, and provides insight into the underlying reasons for the differing behaviour observed in TEM experiments of low-dose ion irradiation in these metals.