During the deformation of Mg alloys, {10–12} extension twin often contributes to the formation of basal texture but rarely assists the nucleation of recrystallization, i.e., effective grain refinement, therefore it seems to make against the improvement of formability and mechanical properties. In this work, {10–12} extension twin has been creatively utilized as a preference nucleation site for static recrystallization (SRX), achieving grain refinement and orientation randomization in a Mg-Gd-Y alloy using multi-directional impact forging (MDIF) and subsequent annealing treatment. Effect of {10–12} extension twin on SRX behavior has been investigated by annealing treatment at 450 °C using quasi-in-situ optical microscopy (OM) and quasi-in-situ electron back-scattering diffraction (EBSD). The microstructural evolution during annealing shows that several SRX gains can nucleate from the grain boundary of untwinned grains, but they only have few influences on the final microstructure due to their limited volume faction and sluggish growth. In contrast, a large number of SRX gains can initiate from {10–12} extension twin and grow up without the confine of twin boundaries. Finally, they consume their parent grains and make the main contribution to grain refinement. This should be attributed to those pinned {10–12} twin boundary, by interacting with various dislocation slips during the MDIF process, which can operate like grain boundary, store enough strain energy, and promote the nucleation of SRX during annealing. On the other hand, SRX grains usually keep initial random orientation and further randomize the forging texture during annealing treatment.

在镁合金的变形过程中，{10-12}延伸孪晶通常有助于基体组织的形成，但很少有助于再结晶的成核，即有效的晶粒细化，因此似乎不利于可塑性和机械性能的提高。在这项工作中，{10-12}延伸孪晶已被创造性地用作静态再结晶（SRX）的优先成核位点，使用多向冲击锻造（MDIF）实现了Mg-Gd-Y合金的晶粒细化和取向随机化以及随后的退火处理。{10-12}延伸孪晶对SRX行为的影响已通过使用准原位光学显微镜（OM）和准原位电子反向散射衍射（EBSD）在450°C的退火处理进行了研究。退火过程中的微观结构演变表明，一些SRX增益可以从未缠绕晶粒的晶界成核，但是由于其有限的体积成分和缓慢的生长，它们对最终的微观结构影响很小。相反，大量的SRX增益可以从{10–12}扩展孪生子开始并在不受孪生子边界限制的情况下成长。最后，他们消耗其母粒，并为晶粒细化做出了主要贡献。这应该归因于在MDIF过程中与各种位错滑移相互作用而固定的{10-12}孪晶边界，它们可以像晶界一样工作，存储足够的应变能并在退火过程中促进SRX的形核。另一方面，