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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 2: Focus: Dislocations in Ceramics: Mechanics, Structures and Functionality (joint session KFM/MA)

KFM 2.4: Hauptvortrag

Montag, 27. März 2023, 15:55–16:25, POT 51

Plastic properties of MgO : Insights from numerical modeling — •Philippe Carrez — Université de Lille, F-59000 Lille, France

Plastic properties of crystalline materials depend not only on the nature of the defects present in the crystal but also and more substantially on their mobilities and mutual interactions. This is typically the case for the creep properties of magnesium oxide (MgO), which has been the subject of numerous investigations over the years. Yet, the atomistic details of dislocation-point defects, dislocation-dislocation or dislocation-grain boundary interactions remain poorly described.

Nowadays, numerical modeling offers the possibility of modeling mechanical properties from the description of the elementary mechanisms of plasticity. As an example, we will discuss the interaction between 1/2<110>{110} dislocations and point defects in MgO. We will show how the edge dislocation core, within a region across the glide planes that expands over several Burgers vector, is a sink for vacancies, and thus enhances the pipe diffusion at moderate temperature. At higher temperature, point-defect absorption or emission along the dislocation lines allow the dislocation climb mechanism and can impact creep properties of MgO. We will thus show how atomic-scale simulations can elucidate the atomic configurations of the various jog configurations structure and give access to their formation energies.