Centre d’Élaboration de Matériaux et d’Etudes Structurales (UPR 8011)


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Understanding the elementary mechanisms of stress induced grain boundary migration

 

N. Combe (SiNano), M. Legros (PPM), F. Mompiou (PPM)

 

Context

Nanocrystalline metals have outstanding mechanical properties but elementary mechanisms are far from being understood as well as their ductility. Since several years, research efforts concentrate on specific grain boundary mechanisms such as stress assisted grain growth or grain boundary sliding. A better knowledge of these mechanisms is a necessary prerequisite for designing improved nanostructured materials either for microelectronics (thin films) or structural applications.

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Gauche : Image MET issue d’une séquence in-situ montrant une disconnection (marche de 2 nm) à l’interface entre deux grains (G1-G2). A droite, simulation atomistique montrant la nucléation d’une paire de disconnections le long du joint de grain.

 

Objectives

In this project, we will combine numerical simulations and in-situ transmission electron microscopy (TEM) experiments for identifying the elementary mechanisms at atomic scale, with a particular attention to the role of interfacial defects called disconnections. We will restrict our objectives to the study of simple metals either polycrystalline thin films or modeled bicrystals. We will carry out in-situ experiments from which the nucleation, dynamics of disconnections and their interactions with dislocations will be observed. The detailed atomic mechanisms as well as the energetics (disconnection nucleation and migration activation energies) will be investigated by Molecular Dynamics simulations using the Nudge Elastic Band method.

 

Ressources

Microscopy, and sample preparation services, regional computing facilities at CALMIP