Dynamics of twinning during compression of Mg micropillars

Session

Poster Session Three

Authors

Petr Harcuba (1), Kristian Mathis (1), Michal Knapek (1), Dávid Ugi (2)

Affiliations

1. Charles University, Faculty of Mathematics and Physics, Department of Physics of Materials
2. Loránd Eötvös University, Department of Materials Physics

Keywords

Micropillar, Micro-indentation, Acoustic emmision, Twinning,

Abstract text

Micro-deformation testing has recently gained far-reaching scientific importance as it provides intrinsic information on the dynamics of plastic deformation which is concealed when bulk materials are tested. In this work, single-crystal Mg micropillars favourably oriented for mechanical twinning were tested in compression with concurrent scanning electron microscopy imaging and acoustic emission measurement. A custom-made micropillar tester, having high spatial and force resolution, together with a novel pillar fabrication process, were used to fully exploit the potential of in-situ SEM testing. Micropillars with a rectangular cross-section of 10 μm were fabricated on the edge of the sample, which could be effectively tested using the micro-testing device in-situ in SEM chamber. It was shown that the nucleation and growth of twins are repeated until the twins form throughout the whole micropillar, from top to bottom. Afterwards, the thickening and coalescence of all these twins take place until the entire micropillar volume is twinned. Simultaneous acoustic emission measurement shows outstanding sensitivity and enable exceptional spatiotemporal resolution of the experiment. In addition, a line-by-line analysis of the scanning electron microscopy images was employed to reveal the twin lateral growth rates, which were shown to be on the order of 10⁻⁵–10⁻⁴ m/s.