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In this work, deformation behavior of an extruded Mg-Zn-Gd-Y-Zr alloy sheet, including mechanical anisotropy and tension-compression asymmetry, were investigated by conducting tension and compression experiments along different directions. Coupling with the strong texture, the role of long-period stacking ordered (LPSO) phases in the deformation behavior was analyzed based on the microscopic plastic deformation theory. The results showed that LPSO phases with different morphologies played different roles in deformation behavior of the strong textured Mg-Zn-Gd-Y-Zr alloy sheet: (i) the irregular-shaped LPSO phases distributed along extrusion direction (ED) brought anisotropic fiber reinforcement and exacerbated the mechanical anisotropy; (ii) the needle-like LPSO phases filled in the grain interior hindered the propagation of twinning boundaries and decreased the tension-compression asymmetry. The results may provide valuable references for the manufacturing of large size Mg/LPSO alloys with low mechanical anisotropy and tension-compression asymmetry, hence making them better to meet the growing need of engineering application.

The microstructure and mechanical anisotropy of the hot rolled Mg-8.1Al-0.7Zn-0.15Ag (wt%) sheets were investigated. Dynamic precipitation and dynamic recrystallization (DRX) are the main features of the microstructures. Compared with the sheet rolled at 673 K, the sheet rolled at 633 K exhibits higher level of dynamic precipitates, finer grain size, more uniform microstructure and better strength. TEM observations reveal that the spherical Mg17Al12 phases which precipitate dynamically do not possess specific orientation with the matrix. Meanwhile, the migration of dynamic recrystallized (DRXed) grain boundaries is retarded by the pinning of fine particles, thereby leading to a remarkable grain refinement. DRX within the compression twins only appear in the alloy sheet rolled at 673 K and give rise to a weakened basal texture. The study on mechanical anisotropy behavior suggests that the reduced anisotropy of the sheet rolled at 633 K may ascribe to the activation of prismatic slip due to the presence of Mg17Al12 phases.

In this study, multi-directional forging (MDF) experiments were conducted to a homogenized Mg-2.36Y-0.98Zn (at%) alloy containing long period stacking ordered (LPSO) phase. Microstructure evolution of the MDFed alloys with different forging passes were systematically investigated, corresponding microhardness development was also concerned. The results revealed that grain refinement, texture weakening and DRX development during MDF were closely relevant to fragmentation of LPSO phase. It was also found that development of average microhardness and mechanical heterogeneity of the MDFed alloys can be attributed to the competition and balance of work hardening, grain refinement and DRX softening. Furthermore, LPSO-related deformation and dynamic recrystallization (DRX) behaviors such as (i) kink-aided DRX (KDRX, this concept was firstly nominated in this study); (ii) particle stimulated nucleation mechanism (PSN) and (iii) pinning effect on DRX nucleus were thoroughly discussed, which should help to understand the unique microstructure evolution of LPSO-containing Mg alloys, and thus offer certain enlightenment for manufacturing LPSO-strengthened Mg alloys with excellent mechanical property.

Two interaction modes between kinking and { 10 1 ‾ 2 } twinning in a Mg–Zn-Gd alloy containing long period stacking ordered (LPSO) phase are thoroughly investigated: (i) when kinking forms prior to twinning, twins concomitantly nuclear at kink boundaries (KBs) and twinning propagation is frequently restricted by two adjacent KBs. By contrast, (ii) when twinning forms prior to kinking, kink deformation locally breaks the twins’ theoretical misorientation to their adjacent matrixes, during which basal slip plays a vital role in accommodating the asynchronous deformation between kinking and twinning.