Interaction between interstitial carbon atoms and a ½ 〈1 1 1〉 self-interstitial atoms loop in an iron matrix: a combined DFT, off lattice KMC and MD study

Abstract

A static and kinetic study of the interaction between a 19 ½ 〈1 1 1〉 self-interstitial atoms loop and C atoms in body-centred cubic iron is presented in this work. An empirical potential matching the density functional theory calculations is used to study the static properties of the system. The usual kinetic Monte-Carlo (KMC) on-lattice restriction is not valid when the material is highly distorted, especially in the presence of a dislocation loop. Therefore, the dynamics of the system are investigated using both molecular dynamics simulations and k-ART, a self-learning/off-lattice atomic kinetic monte-carlo. The presented work is thus a full study of the C-loop and the C2-loop systems. A good agreement is observed between the statics and the kinetics (e.g. the discovery of a zone of stability of the C atom around the Fe cluster where the C can almost freely move), even though the kinetics show some unexpected behaviours of the studied systems. The pinning time of the loop induced by the C atoms is also estimated.

Initial Stage Carbonization of γ-Fe(100) Surface in C2H2 under High Temperature: A Molecular Dynamic Simulation

“…Regarding to the previous work on Fe-C alloy by MD simulations, most of them focused on the carbon diffusion in bcc or fcc iron [7][8][9][10][11]. The mutual effects between carbon interstitial and defects in iron have been intensely studied [12][13][14][15][16][17][18][19]. Furthermore, some of them were well devoted to the phase transformation mechanisms in Fe-C alloys [20][21][22][23][24].…”

Investigating the kinetics of the formation of a C Cottrell atmosphere around a screw dislocation in bcc iron: a mixed-lattice atomistic kinetic Monte-Carlo analysis

“…K-ART is based on the open-ended event searching method ART nouveau, a very efficient method for exploring the local energy landscape (Mousseau and Barkema 1998), (Barkema and Mousseau 1996), (Malek and Mousseau 2000) and NAUTY (McKay 1981), a topologicalanalysis library for event classification. K-ART can correctly predict the kinetics of distorted systems such as C diffusion close to dislocation loops (Candela et al 2018), vacancy and C interaction in bulk Fe (Restrepo et al 2016) and long-time relaxation after ion-bombardment (Béland et al 2013). Treatment of distorted or disordered environment is costly, however, every step requires thousands of force evaluations, reducing k-ART's efficiency for systems with a large number of mobile defects.…”