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Atomistic-Continuum Modeling Of Dislocation Interaction With Y2O3 Particles In Iron

Oxide dispersion strengthened (ODS) steels are promising candidates for applications in fusion and fission rectors. Y2O3 particles dispersed in an iron matrix drastically improve the strength without adverse effects on ductility. We investigate here details of the dislocation core structure in Y2O3 precipitates, and at the interface between the iron matrix and the Y2O3 precipitate. We also simulate dislocation interaction with nano-size Y2O3 precipitates. It is shown that the γ-surface energies on planes between oxygen atoms and metallic atoms are extremely high, and that dislocations in an iron matrix cannot penetrate into Y2O3 particles. Three-dimensional parametric dislocation dynamics simulations of the interaction between an edge dislocation and an Y2O3 particle are carried out. The results show that the critical resolved shear stress (CRSS) has a strong dependence on the lattice mismatch Y2O3 particles and the iron matrix, and that it is lower than analytically calculated values of the Orowan stress.

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