Influence of the picosecond defect distribution on damage accumulation in irradiated α-Fe

The importance of the defect distribution produced in the first few picoseconds of a collision cascade on long-term damage evolution is studied with molecular dynamics and kinetic Monte Carlo (KMC) methods. Three different interatomic potentials are used to obtain the primary damage produced by energetic recoils in alpha-Fe. Contrary to previous results, a dependence of cluster-size distribution with recoil energy is obtained. Moreover, large variations in this distribution are observed depending on the interatomic potential. Using the results for 50 keV collision cascades, damage accumulation is modeled with KMC. The accumulation rate of damage visible under transmission electron microscopy predicted by KMC depends significantly on the database used for cascade damage and, therefore, on the interatomic potential. Based on these results, we show that the comparison of cluster-size distributions with experiments can be used to test the reliability of interatomic potentials.