Abstract
Simulations of displacement cascade annealing were carried out using object kinetic Monte Carlo based
on an extensive MD database including various primary knock-on atom energies and directions. The sensitivity
of the results to a broad range of material and model parameters was examined. The diffusion
mechanism of interstitial clusters has been identified to have the most significant impact on the fraction
of stable interstitials that escape the cascade region. The maximum level of recombination was observed
for the limiting case in which all interstitial clusters exhibit 3D random walk diffusion. The OKMC model
was parameterized using two alternative sets of defect migration and binding energies, one from ab initio
calculations and the second from an empirical potential. The two sets of data predict essentially the same
fraction of surviving defects but different times associated with the defect escape processes. This study
provides a comprehensive picture of the first phase of long-term defect evolution in bcc iron and generates
information that can be used as input data for mean field rate theory (MFRT) to predict the microstructure
evolution of materials under irradiation. In addition, the limitations of the current OKMC model
are discussed and a potential way to overcome these limitations is outlined.
