Fig. 1. Identification for the activated slip systems by slip trace and lattice rotation analysis. (a) Inverse pole figure (IPF) map of Grain A and its neighboring grains. (b) SEM image showing two kinds of surface slip traces in Grain A. (c) 30 simulated slip traces of Grain A. (d){0002}pole figure of Grain A. The (0002) pole was stretched along two directions: the streak from 1 to 2 is caused by the basal <a> dislocation slip; the streak from 1 to 3 is caused by the pyramidal I <c + a> dislocation slip.

Fig. 2. (a) IPF map of the region of interest before deformation. (b) Pole figures corresponding to (a). (c) True stress-true strain curve of the in-situ tensile test, during which the SEM/EBSD imaging was conducted at 0% (S0), 1.6% (S1), 4.4% (S2), 6.8% (S3, SEM only), 8.8% (S4), and 12.8% (S5) strains. (d) Work hardening curve corresponding to the true strain-true stress curve presented in (c). The monotonic decrease of the work hardening response was interrupted during the in-situ test.

Fig. 3. IPF maps showing microstructure evolution with tensile strain.

Fig. 4. Typical morphologies of (a) intragranular non-basal slip traces and (b, c) non-basal slip traces near GBs.

Fig. 5. Proportion of grains showing the non-basal dislocation slip traces at different strains for the Mg-5Y alloy. (a) Slip traces inside grains and (b) slip traces near GBs.

Fig. 6. Schmid factors of the activated non-basal dislocation slip (SFobserved) in comparison to the maximum SFs (SFmax) of the corresponding non-basal slip modes at four strains (in the four rows). The left column presents the observed slip within the grains. The right column presents the observed slip within the grains near GBs, showing that most of the slip near GBs do not follow the Schmid law.

Fig. 7. Experimentally determined shear stresses of the activated dislocation slip in the Mg-5Y alloy.

Fig. 8. Comparison of the simulated true stress-strain curve (the dashed line) by the VPSC simulation and the one (the solid line) by the in-situ tensile test shows very close agreement.

Fig. 9. Comparison of the simulated (the left two columns) and the measured (the right two columns) texture for the Mg-Y alloy at (a) 1.6%, (b) 4.4%, (c) 8.8%, and (d) 12.8% strains.

Fig. 10. Simulated relative activity plot for the five slip modes of the Mg-Y alloy as a function of the applied strain according to the VPSC simulation.

Fig. 11. Bright-field image for the <c + a> dislocation cross-slip near GB in the Mg-5Y alloy with a 4% strain, under the g = 0002 diffraction condition near the [11$\bar{2}$0] zone axis. The dislocation segment marked with the blue arrow could be ascribed to the <c + a> dislocation slipped on the pyramidal II plane. The dislocation marked with the red arrow deviates from the [10$\bar{1}$0] by ~60°, suggesting cross-slip occurred (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).

Fig. 12. Dark-field image for the <c + a> dislocation cross-slip near GB in the extruded Mg-0.47Ca (wt.%) alloy with an 8% tensile strain, under the g = 0002 diffraction condition near the [11$\bar{2}$0] zone axis.