Kinetic Monte Carlo Simulations of Precipitation

Abstract

We present some recent applications of the atomistic diffusion model and of the kinetic Monte Carlo (KMC) algorithm to systems of industrial interest, i.e. Al‐Zr‐Sc and Fe‐Nb‐C alloys, or to model systems. These applications include study of homogeneous and heterogeneous precipitation as well as of phase transformation under irradiation. The KMC simulations are also used to test the main assumptions and limitations of more simple models and classical theories used in the industry, e.g. the classical nucleation theory.

Transmission Electron Microscopy and Nano‐Precipitation

“…Atom Probe Tomography and Small-Angle X-ray Scattering), and also predicted by kinetic Monte Carlo (KMC) calculations, [17] all these results being obtained in the perimeter of the CPR 'Pré-cipitation'. [18] …”

“…[9] These systems have then been experimentally characterized by APT, [21,22] Small-Angle Neutron Scattering, [23] TEM and associated techniques, [24] and partly investigated by atomistic simulation, i.e. kinetic Monte Carlo (KMC) (see [17] ).…”

Modeling Microstructure and Irradiation Effects

“…Following the suggestion of Reference 21, we use the term MFRT here. KMC methods can be applied to objects (OKMC [22][23][24] ), events (EKMC [25,26] ), or atoms (AKMC [27][28][29][30][31][32][33][34][35][36] ) in a specific volume. Both KMC and MFRT can be globally defined as coarse-grained models, because atoms are not explicitly treated in either except in the atomistic (or lattice) KMC, i.e., the AKMC.…”

“…In Reference 173, spatial correlations were shown to strongly influence the cluster size distributions in the long term. KMC methods can be applied to study the evolution of systems of mobile species, such as atoms in atomistic KMC [27][28][29][30][31][33][34][35][36]222] or larger defects, formed, for instance, under irradiation in so-called coarser-grained KMC models. [22][23][24][25][26]223] Many coarse-grained KMC models were formulated to describe the long-term evolution of the primary damage produced by irradiation.…”

“…Pareige and co-workers investigated ordering and phase separation in NiCrAl alloys, which are model systems of Ni-based superalloys used in the aerospace industry. [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.…”