Simulation of radiation damages in molybdenum by combining molecular dynamics and OKMC

Abstract

In this paper, radiation defects in bcc molybdenum with the primary knock-on atom (PKA) energies of 2–40 keV are simulated by the molecular dynamics. The binding energy of single point defect-to-defect clusters increases with the cluster size. The stability and mobility of point defects and defect clusters are analyzed. The interstitial-type clusters are found to be easily migrating along the direction with low barriers (0.01–0.10 eV). Then, the object kinetic Monte Carlo is used to gain insight into the long-term defect evolution in the cascade. The simulation results indicate that Stage I almost occurs at annealing temperature of 100 K, which corresponds to the correlated recombination resulting from the motion of small interstitial clusters (n ≤ 2). The formation of substage partly as result of the small vacancy clusters motion. At about 460 K, the Stage II starts because of uncorrelated recombination due to an emitting mechanism of larger clusters. Size distribution of the clusters at the cascade quenching stage is positively correlated with the PKA energies, affecting notably the subsequent annealing process.