针对镁合金室温塑性差关键科学问题，通过混晶结构及弱基面织构解决“Mg合金强塑性同时提高”瓶颈难题。创新思路在于巧妙利用大压下量衬板控轧（HPR）新方法促进微观非均匀变形，实现Mg-Al-Zn合金混晶结构(超细晶、微米晶)和发散织构协同调控制备；基于混晶结构促进加工硬化、弱基面织构改善塑性新机制，实现强塑性同时提高；通过研究混晶结构形成机制，提供镁合金弱织构混晶结构组织设计准则；基于混晶结构及基面织构特性对强塑性同时提高影响规律的研究，建立HPR制备-混晶组织-强塑性的定性关系，优化出较佳混晶结构（尺寸、比例）及基面织构特性（强度、分布），实现高强塑性Mg-Al-Zn合金可控制备。在理论上的创新：揭示衬板控轧镁合金混晶结构组织形成及基面织构弱化机制；阐明混晶结构和弱基面织构对镁合金强塑性同时提高的作用机制，为开发高性能Mg-Al-Zn合金提供借鉴。

The present project focuses on a key challenge that Mg alloys usually suffer from low ductility, aiming to overcome the key difficulty, i.e., achieving a simultaneous high strength and high ductility, for Mg alloys. The innovation of this project lies in the fact that a new preparation method, i.e., hard-plate rolling (HPR), was utilized to promote heterogeneous plastic deformation, achieving a multimodal grain structure (the coexistence of ultrafine- and micron grains) and weakened basal texture, in Mg-Al-Zn alloys. Based on the fact that the multimodal grain structure favors for enhanced work hardening while a weakened basal texture promotes the plasticity of Mg alloys, a simultaneous high strength and ductility can be achieved in Mg-Al-Zn alloys. Studying the formation mechanism of the multimodal grain structure, and accordingly providing preparing principle for multimodal-grain-structured Mg alloys; Investigating the influence of the multimodal grain structure and weakened basal texture on the mechanism for the simultaneous increase in strength and ductility, and accordingly, establishing HPR processing-multimodal grain structure-strength and ductility relations, optimizing the multimodal grain structure (grain size, volume fractions) and basal texture, realizing the controllable fabrication of Mg-Al-Zn alloys with both high- strength and ductility. The theoretical innovation of this project includes revealing formation mechanisms for the multimodal grain structure and weakened basal texture in HPR Mg-Al-Zn alloys; clarifying effects of multimodal grain structure and weakened basal texture on mechanisms for the simultaneous high- strength and ductility of Mg alloys; providing necessary basis for the development of new high strength and high ductility Mg alloys.