ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Onset of plasticity under nanoindentation: influence of the interatomic potential

Date: 27.10.2008
Place: International Conference on Multiscale Materials Modelling, Tallahassee, Florida, USA

Gerolf Ziegenhain, Physics Department, Technical University Kaiserslautern, Kaiserslautern, Germany
Alexander Hartmaier
Herbert Urbassek, Technische Universität Kaiserslautern, Kaiserslautern, Germany

In recent years the computer power has become large enough to solve Newton's equations of motion for a large number of particles numerically. This enables us to simulate the plastic behavior of materials on the atomistic scale. Using the molecular dynamics method we investigate specifically the onset of plasticity under nanoindentation. In order to understand the atomistic plasticity and ductility of metals we address the question which microscopic properties are of importance for modelling plastic behavior. The microscopic properties - such as the cohesive energy, the elastic moduli, and the energy of point, line and planar defects - are determined through the potentials. Focussing on fcc materials, we investigate different pair and many-body potentials with respect to plasticity. It turns out that the dislocation nucleation under the indenter does not depend on the unstable stacking fault energy, which however governs the behavior of fully developped plasticity. Embryonic plasticity is dominated by crystal structure alone; it is well described even by simple pair potential.

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