Interaction between interstitial Frank loops and edge dislocations on a Fe-10Ni-20Cr: a molecular dynamics study

Interaction between interstitial Frank loops and edge dislocations on a Fe-10Ni-20Cr: a molecular dynamics study.
J.B. Baudouin¹, G. Monnet¹, M. Perez², C. domain¹ and A. Nomoto^3
1Electricité de France – MMC, av. des Renardières, F-77818 Moret sur Loing, France

²Université de Lyon – INSA Lyon – MATEIS – UMR CNRS 5510 – F69621 Villeurbanne – France

³Central Research Institute of Electric Power Industry – 2-11-1, Iwado Kita, Komae-shi, Tokyo 201-8511, Japan
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Austenitic stainless steels are used in nuclear industry as internal structures in nuclear light-water type reactors. Once in service, these structures undergo harsh conditions of usage as neutron irradiation, corrosion and mechanical stress act simultaneously. Understanding deformation mechanisms in irradiated materials is required to optimize the lifetime of nuclear reactors. This study is dedicated to the understanding of edge dislocation motion in a Fe-10Ni-20Cr (model AISI 316L stainless steel). Molecular dynamic simulations are performed based on a recently developped FeNiCr EAM potential. Stacking fault energy and elastic constants are well reproduced and FCC phase is stable in the temperature range 0-900K. First, the core structure of the dislocation has been investigated. The dislocation splits into two partials, whose distance depends on the stacking fault energy (fixed for a given alloy composition) and the external applied stress. It has been shown that only two components of the stress tensor influence the motion of the two partials. The second part is focused on the friction stress. Quantitative effect of alloying elements on friction stress of screw and edge dislocations are measured. Finally, reaction paths between Frank loop of interstitials and an edge dislocation were studied. Two diameters of Frank loops have been investigated where the small one is supposed to reproduce black dot defects. We found that edge dislocation shears Frank loop into three main reaction pathways. It appears that the variant and the size of the Frank loop influence strongly the reaction. The resulting interaction with the Frank loop seems to be strongly affected by the alloying elements distribution.