Magnesium (Mg) alloys, as the lightest metal engineering materials, have broad application prospects. However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously. Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility. In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced. Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence. This review can be used as a reference for further development of high-performance fine-grained Mg alloys.

镁（Mg）合金作为最轻的金属工程材料，具有广阔的应用前景。然而，传统的镁合金的强度和延性仍然相对较低，并且难以同时提高。通过基于晶界强化和变形机理转变的变形过程细化晶粒尺寸是制备高强度高延展性镁合金的可行策略之一。本文综述了晶粒尺寸对镁合金强度和延展性的影响，并介绍了通过各种严格的塑性变形技术和改进的传统变形技术开发的具有高强度和高延展性的细晶粒镁合金。尽管已经取得了一些成就，晶粒尺寸对各种镁合金的影响很少有系统地讨论，某些关键机理尚不清楚或缺乏直接的微观证据。这篇评论可以作为进一步开发高性能细晶粒镁合金的参考。