ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Deformation and fracture at grain boundaries: Can we include atomistic effects in mesoscale descriptions via a few physical parameters?

Date: 20.06.2017
Place: 14th International Conference on Fracture, Ixia, Greece

Rebecca Janisch
Mansour Kanani
Xueyong Pang
Arshad Tahir
Alexander Hartmaier

We investigate the mechanical properties of interfaces via ab-initio density functional theory calculations as well as molecular dynamics simulations using embedded atom method type potentials. The goal is to develop a scale-bridging model of their effect on the deformation behaviour of microstructures, which captures the relevant processes on the microscopic scale and describes their effect by characteristic parameters that are passed on to the next higher length scale. In this work such parameters are identified from ab-initio density functional theory calculations of the response of grain boundaries to a tensile or shear load, e.g. the work of separation and strength of an interface, or the shape parameters of the energy barriers for interfacial sliding. The main achievements so far are a) the formulation of a physics based potential for interfaces under a three-dimensional load, from which constitutive relationships can be derived, b) the inclusion of segregation and co-segregation effects, and c) the correlation of fundamental properties that can be obtained from quasistatic ab-initio calculations (and define the coupling potential) with the atomistic mechanisms. It will be discussed to what extent this relation between the features of the energy landscape and the actual deformation process justifies a description of constitutive relationships based on the simplified interplanar potential.

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