Hardening Mechanisms upon Profuse Twinning in Pure Magnesium

Oppedal, A. L., El Kadiri, H., Tomé, C. N., Baird, J., Vogel, S. C., Kaschner, G. C., & Horstemeyer, M. (2011). Hardening Mechanisms upon Profuse Twinning in Pure Magnesium. TMS 2011. San Diego, CA: TMS (The Minerals, Metals & Materials Society).

Textured hexagonal close packed double-lattice structures show stronger anisotropy than textured single-lattice structures. The reason lies behind the necessity to activate glide twinning and hard slip dislocation modes. Although the mechanisms behind activation of dislocations with non-basal Burgers vectors are still not fundamentally understood, the effect of twinning on hardening presents the most substantial challenge to polycrystal plasticity modelers. The origin of the increasing strain hardening rate regime (Regime II) upon profuse twinning is still not fundamentally clear. Previous successful attempts to fit stress-strain behavior based on a Hall-Petch effect by twin segmentation led to discrepancies in predicting intermediate textures and/or twin volume fraction evolution. A recent dislocation-based hardening rule incorporated into the Visco-Plastic Self-Consistent (VPSC) model allows slip and twinning to be physically coupled in the simulations. In this paper, we investigate hardening mechanisms in pure magnesium and apply a dislocation based formalism to model anisotropy.