Modelling Magnesium Alloys for Improved Isotropic and Symmetric Yield Behaviour

Age-hardenable wrought magnesium alloys suffer from high mechanical anisotropy and asymmetry which can be reduced by the correct choice of precipitate shape and habit plane. In this paper, the effect of combining precipitates of different types has been predicted using modified Orowan strengthening theory and visco-plastic self-consistent modelling, with the goal of designing more isotropic magnesium alloys. It was predicted that the correct combination of \( \left\langle {11\bar{2}0} \right\rangle \) basal laths and c-axis rods would be expected to reduce yield anisotropy and asymmetry, whilst also providing high strength, consistent with published data on a Mg-Sn-Zn-Al-Na alloy. The model was further expanded to relate precipitate volume fractions to alloying content so that weight-optimised alloys with desirable isotropy, symmetry and strength could be designed.