Influence of the stress field due to pressurized nanometric He bubbles on the mobility of an edge dislocation in iron

Abstract

Voids and He bubbles are strong obstacles to dislocation, which induce hardening and loss of ductility. In Fe, molecular dynamics simulation is used to investigate the basic mechanisms of the interaction between a moving edge dislocation and a void or He bubble, as a function of its He content, temperature, interatomic potentials and interaction geometry. Different interatomic potentials for Fe–Fe and Fe–He interactions are used. It appears that temperature eases the dislocation release, due to the increased mobility of the screw segments appearing on the dislocation line upon bowing from the void or He bubble. The mobility includes the cross-slipping of these segments, which leads to the formation of a jog. It appears that the He bubble induces an inhomogeneous stress field in its surroundings, which strongly influences the dislocation passage depending on the geometry of the interaction.

Keywords:

• molecular dynamics
• dislocations
• strengthening mechanisms
• iron

Acknowledgements

This work, supported by the European Communities under the contract of Association between EURATOM and Confédération Suisse, was carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission. The Paul Scherrer Institute is acknowledged for the overall use of the facilities.