|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Advanced Thermo-mechanical Characterization of Materials with Special Emphasis on In Situ Techniques
||Crystal Size and Temperature Effects on the Transformation in Deformation Modes in Twin Oriented Mg Single Crystals
||Gi-Dong Sim, Kelvin Y. Xie, Kevin J. Hemker, Jaafar A. El-Awady
|On-Site Speaker (Planned)
We present a comprehensive study to understand crystal size and temperature effects on the transformation in deformation modes in twin oriented Mg single crystals. Single crystal micropillars with size ranging from 2 to 23 μm were fabricated, then tested by in-situ SEM nanoindentation. First, we discuss crystal size effect on the transformation of deformation mechanisms at room temperature. The experiments reveal two regimes of size effects: (1) single twin propagation, where a typical “smaller the stronger” behavior was dominant in pillars ≤ 18 μm in diameter, and (2) twin-twin interaction, which results in anomalous strain hardening in pillars > 18 μm. In the second part, we report temperature effect (room temperature, 100oC, and 150oC) on the deformation mechanism at a fixed crystal size (6 μm). Unusually high flow stress was observed at 100oC while twinning still governs plasticity. Surprisingly, at 150oC, we observed strain softening due to dislocation-mediated plasticity.
||Planned: Supplemental Proceedings volume