Extruded magnesium alloys with a strong basal texture present a strong tension-compression asymmetry in deformation due to the fact that dislocation slips dominate plastic deformation in tension along the extrusion direction (ED) whereas twinning dominates plastic deformation in compression along the ED. The deformation characteristics allows for a study of the twin-slip interaction by introducing dislocations in the material before activating twinning. In the current work, dislocations of different densities are first introduced by prestraining in tension an extruded Mg-3Al-1Zn alloy along the ED to 5% and 10% of total strain, respectively. Then the loading direction is reversed to compression such that deformation twinning is activated. The results show that the hardening rate after different prestrains remains nearly unchanged, indicating that twin-slip interaction produces negligible effect on strain hardening. The yield stress in the reversed compression increases only slightly with increasing prestrain: ~20 MPa at every 5% increase in prestrain. Electron backscatter diffraction results show that prestraining can retard twin nucleation at the very early stage of plastic deformation, but it has little effect on twin growth.

由于位错滑移主导了沿拉伸方向（ED）的拉伸塑性变形，而孪晶支配了沿ED的压缩塑性变形，因此具有强基体结构的挤压镁合金在变形中表现出很强的拉伸-压缩不对称性。变形特性允许在激活孪晶之前在材料中引入位错，从而研究孪晶滑移相互作用。在当前的工作中，首先通过将拉伸的Mg-3Al-1Zn合金沿ED沿拉伸方向预拉伸分别占总应变的5％和10％，来引入不同密度的位错。然后，将加载方向反转为压缩，从而激活变形孪生。结果表明，不同预应力后的硬化速率几乎保持不变，表明双滑相互作用对应变硬化的影响可忽略不计。反向压缩中的屈服应力仅随预应变的增加而略有增加：预应变每增加5％，则屈服应力约为20 MPa。电子背散射衍射结果表明，预应变可以在塑性变形的早期阻止双晶核化，但对双晶生长几乎没有影响。