Helium bubble nucleation in bcc iron studied by kinetic Monte Carlo simulations

Binding of HenV clusters to α-Fe grain boundaries

“…Ascertaining the reactions that occur and quantifying their energetics are important for a fundamental understanding of how point defects, impurities, substitutional atoms, and helium atoms interact in the single crystal lattice of a-Fe. Furthermore, this information is useful for models that explore the kinetics of He diffusion, trapping (clustering), and detrapping (emission), such as rate theory models, [32][33][34][35] kinetic Monte Carlo models, 36,37 and/or phase field models. 38,39 The grain boundary itself and its atomic configuration within these alloy systems plays a significant role in trapping point defects and various atomic species.…”

Multiscale Materials Modeling of Structural Materials for Next Generation Nuclear Reactors

“…The kinetic Monte Carlo model (Deo, Srivilliputhur et al 2006;Deo, Okuniewski et al 2007;Deo, Srinivasan et al 2007) consists of helium interstitials on the octahedral sublattice and vacancies on the bcc iron lattice. The migration of the free (not clustered) helium is shown in figure 5(a) and that of the vacancies and self interstitial atoms is shown in Figure 5(b).…”

“…The dependence on irradiation dose (expressed as dpa) of the defect cluster density (N) and the defect diameter (d) are taken from atomic level kinetic Monte Carlo (kMC) simulations and experimental observations (Deo et al 2006;Deo, Baskes et al 2007) The kMC model takes atomic level information of the migration energies and jump attempt frequencies of irradiation induced defects (interstitials, vacancies) and transmutation products (e.g., helium under high energy proton irradiation), and evolves the microstructure according to the rates of migration of these defects. The defects are allowed to cluster, and new irradiation damage is introduced during the simulation according to the irradiation dose rate.…”

Modeling Microstructure and Irradiation Effects

“…[30] In Al alloys, the introduction of transition elements such as Mn, Zr, or Sc leads to the formation of ordered precipitates, which increase the tensile strength and inhibit recrystallization, and Clouet et al investigated the formation of L12 precipitates in Al-Zr-Sc alloys [36,256,257] by means of a pair bond AKMC model. The behavior of He in Fe has also been investigated using this technique: the nucleation of He bubbles in bcc Fe was modeled by Deo et al, [258] and He-bubble migration in bcc Fe by Morishita et al [259] Figure 5 represents the microstructure of an Fe alloy containing 1.12 pct at. Mn and 0.73 pct at Ni at 9.3 9 10 À3 dpa after being neutron irradiated at 573 K (300°C) under a rate of 5.8 9 10 À5 dpaAEs À1 .…”