ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Coupled atomistic-FEM analysis of light elements at dislocation cores

The influence of light elements on the mobility of dislocations and thus on the deformation behaviour of a material strongly depends on the details of the interatomic interactions, which makes an atomistic modelling with reliable potentials (BOP, TB, DFT) desirable. At the same time we can only understand the atomistic mechanisms properly if the deformation is modelled with sufficient cell size and realistic boundary conditions. To fulfill both requirements, a coupling scheme between an atomistic and a continuum regime will be implemented, in which the atomistic region will contain the dislocation core and the continuum region can accommodate long range stresses and will be used to impose realistic external loads on the system.

FEM representation of a screw dislocation. Different colours mark different displacements along z.

Currently the coupling is established using empirical potentials and the IMD code, to allow a quick assessment of relevant situations (edge and core dislocations with straight and kinked dislocation lines) and gain experience with deformation simulations in 2D and 3D. In a later stage the atomic interactions shall be represented by bond-order potentials or even ab-initio to get a realistic description of Fe-C and Fe-H interactions.

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