Abstract:

A heterogeneous transverse direction (TD)-tilt texture in rare-earth-containing magnesium plates typically results in obvious in-plane anisotropy in their mechanical behavior. In this study, the planar anisotropy of yield strength during tension along the rolling direction (RD) and TD is quantified in a Mg-0.1Zn-0.5Gd plate with different grain sizes and texture patterns. Regardless of the grain size, the yield strength along the RD is approximately 33 MPa higher than that along the TD in the plate with the c-axis distributed in an elliptical region. In contrast, a near in-plane isotropy of the mechanical properties is observed in the plate with the c-axis aligned primarily in a circular region. Microstructural analysis and crystal plasticity simulations show that basal slip prevailed during the tension test, with varied complementary deformation modes in different loading directions. Prismatic slip is the main complementary deformation mode during tension along the RD, whereas tensile twinning is important during tension along the TD. The yield anisotropy is primarily attributed to the varied intercept ${\sigma }_{0}$ in the Hall–Petch relation during tension along different directions. The invariant Hall–Petch slope $k$ results in grain size independence on the mechanical anisotropy. Finally, a quantitative discussion on the differences of ${\sigma }_{0}$ and the similarity in $k$ related to the relative activity of the deformation modes is provided.

Key words: Mg alloy, Plastic deformation, Yield stress, Anisotropy, Texture