Fig. 1. (a) Schematic diagram of the experimental process, (b) schematic diagram of compression tests, (c) sampling methods in the present study, (d) SEM image of the as-cast sample, (e) SEM image of the sample after solution treatment.

Fig. 2. EBSD observations in the initial microstructure of the Mg-4Y-2Nd-1Sm-0.5Zr alloy after solution treatment. (a) Inverse polar figure (IPF) map, (b) Euler map, (c) grain boundary map, (d) the corresponding pole figures of {0002}, {10-10}, and {11-20}, (e) grain size distribution map of (a), (f) misorientation angle distribution map of (c).

Fig. 3. True stress-true strain curves of the Mg-4Y-2Nd-1Sm-0.5Zr alloy of 0.8 at (a) 350 °C, (b) 400 °C, (c) 450 °C and (d) 500 °C.

Fig. 4. Compensation of the adiabatic heating effect: (a) extrapolation correction for each temperature at 5 s-1; (b) extrapolation correction for each temperature at 1 s-1; (c) extrapolation correction for each temperature at 0.1 s-1 and (d) an example of linear fitting of the measured points and extrapolation correction conducted at 5 s-1 and a true strain of 0.35.

Fig. 5. Calculation of material constants in constitutive equations, (a) slopes of∂ln$\dot \varepsilon$-∂lnσ for ${n_1}$; (b) slopes of∂ln$\dot \varepsilon$/∂σ for β; (c) slopes of ∂ln$\dot \varepsilon$/∂ln[sh(ασ)] for n; (d) slopes∂ln[sh(ασ)]-1000/T of for calculating Q.

Fig. 6. Plots and relationship of lnZ-nln[sh(ασ)].

Fig. 7. Processing maps assembled by the efficiency of power dissipation (η) contours with flow instability (ξ) color background, for a true strain of (a) 0.4 and (b) 0.8.

Fig. 8. IPF maps of all conditions at a true strain of 0.8.

Fig. 9. (a)-(d) The misorientation angle distribution of all conditions at a true strain of 0.8; (e) The average misorientation angles of all conditions in (a)-(d).

Fig. 10. IPF maps of partitioned DRX grains in Fig. 8.

Fig. 11. The average grain size of DRX grains in Fig. 10.

Fig. 12. The volume fraction of DRX grains in Fig. 10.

Fig. 13. (0002) pole figures of partitioned DRX grains in Fig. 10.

Fig. 14. Relationship of (a) θ - σ and (b) $- \left( {\frac{{\partial \theta }}{{\partial \sigma }}} \right)$-σ and (c) XDRX - ɛ at the temperature of 500 °C and strain rate of 0.01 s-1.

Fig. 15. (a-i) IPF maps of 500 °C / 0.01 s-1 ((a) strain 0.2; (b) strain 0.4; (c) strain 0.8), 500 °C / 5 s-1 ((d) strain 0.2; (e) strain 0.4; (f) strain 0.8), and 350 °C / 0.01 s-1 ((g) strain 0.2; (h) strain 0.4; (i) strain 0.8) and (j, k) orientation gradient measured by line a-b and c-d in (g) and (h); (l, m) orientation gradient measured by line e-f and g-h in (b) and (d).

Fig. 16. Stress component n1 obtained for a true strain of (a) 0.4 and (b) 0.8.

Fig. 17. Microstructural observations at 350 °C / 0.01 s-1 /0.2 and 350 °C / 0.01 s-1 / 0.4: (a) IPF map for 0.2 and (b) 0.4; (c) typical grain and twin A and (d) those of B; (e) the corresponding polar figures of (c); (f) the corresponding polar figures of (d).

Fig. 18. The corresponding (a) KAM map and (b) value in Fig. 16(a).

Fig. 19. Microstructural observations at 350 °C / 0.01 s-1/0.4: (a) DRX grains occurring in {10-12} tensile twins (b).

Fig. 20. Schematic diagram of the overall mechanisms.