现有研究中Mg-Zn-Gd基准晶增强镁合金热塑性变形前均匀化热处理的温度较低，热处理后合金中粗大的准晶相依旧存在，挤压后破碎成微米尺度的准晶颗粒，微米级准晶的存在使得镁固溶体中合金元素含量较低而导致析出的纳米准晶分数较低。此外，在揭示合金的变形行为时多研究本构方程、准晶析出等问题，然而对这些纳米准晶增强相自身的变形及开裂行为及其对Mg-Zn-Gd基准晶增强镁合金的性能的影响未做系统深入研究。针对上述问题，本项目提出采用多级固溶热处理新工艺逐步递进式实现铸态合金中的粗大第二相完全固溶，再采用时效和轧制变形两种方式来调控纳米准晶的析出，据此得到大体积分数纳米准晶增强Mg-2.4Zn-0.4Gd变形镁合金。在此基础上，再拟集中研究合金中纳米准晶相在合金室温变形过程中的变形和开裂行为，为揭示纳米准晶增强变形镁合金的强韧化机制提供理论支持，对推动我国新一代高强韧变形镁合金的研究和应用具有重要意义。

In previous studies about Mg-Zn-Gd-based alloys reinforced with icosahedral quasicrystals (I-phase), to prevent over-heated and over-melted, the homogenized heat treatment temperature before extrusion is about 400℃. Dendritic I-phase remain in the Mg matrix after homogenization and then broken into microscale particles during thermal-mechanical processing. The volume fraction of nanoscale I-phase precipitation is limited because these microscale I-phase particles occurrence reduces the contents of alloying elements in Mg matrix solid-solution. In addition, many researchers have studied deformation behavior of Mg alloys strengthened by I-phase, and most of these studies are focused on constitutive equation establishment and secondary phase precipitation. Although these studies are useful and important for understanding deformation behaviors of Mg alloys reinforced with I-phase, few studies have been done on the deformation and fracture behavior of I-phase themselves. Therefore, increasing the heat treatment temperature was proposed in the project by using the way of multi-stage solid solution, and then control the precipitation of nanoscale I-phase by using the method of statical aging or thermal-mechanical processing. Finally, Mg-Zn-Gd alloy with large volume fraction of nanoscale I-phase and high properties was obtained. Baseing on the developing of high performance Mg-2.4Zn-0.4Gd（at.%）alloy reinforced with large volume fraction of nanoscale I-phase, we focus on the deformation and crack behavior of nanoscale I-phase in the alloy during deformation at room temperature. The results will help to provide theoretical and technical supports for revealing the strengthening and toughening mechanisms of magnesium alloys reinforced with I-phase, which is meaningful for accelerating the research and application of deformation magnesium alloys with high strength and toughness.