Deformation behavior of micron-sized polycrystalline gold particles studied by in situ compression experiments and frictional finite element simulation

• Mechanical properties of micron-sized polycrystalline gold particles
• In situ SEM testing of a statistical significant particle ensemble
• Elastic-perfectly plastic deformation behavior obtained from FEM
• Detailed analysis of deformation modes
• Interfacial friction affects deformation behavior.

We present a combined experimental and finite element study on the deformation behavior of micron-sized polycrystalline gold particles. This study enables detailed insights into the underlying deformation mechanisms of the particles. Scanning electron microscope supported in situ uniaxial compression experiments of the single spherical polycrystalline gold particles were performed in the size range of 1 μm by using a custom built manipulation device. By testing a large number of particles stress–strain data and information on the particle morphology were obtained with statistical significance. The experimentally observed stress–strain behavior and the geometric shape of the stressed particles were found to be in excellent agreement with the elastic-perfectly plastic finite element model accounting for frictional effects at the contact interfaces. A significantly increased yield strength compared to bulk gold was found — grain size strengthening according to the Hall–Petch relation was identified as the main hardening mechanism. Hardness was found to vary with strain — an effect related to the altering geometric shape of the particles during compression. Comparison to a frictionless finite element model revealed the necessity of considering the effect of friction. These findings are not restricted to gold particles, but should be applicable to a wide range of elastic-perfectly plastic materials.

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