LPSO相形态与晶体取向对Mg-Gd-Y-Zn-Zr合金变形机制的协同影响及作用机理

Effects of the LPSO phase with different morphologies and crystal orientation on deformation mechanism of Mg-Gd-Y-Zn-Zr alloy during hot rolling process was studied by using various modern and advanced testing and analysis techniques and crystal plasticity theory. The deformation mechanism of grains with a fixed morphology of the LPSO phase and different crystal orientation was studied. The distribution crystal orientation in different grains was plotted in Euler space and the orientation distribution characteristic was studied. In addition, the orientation dependence of deformation mechanism was identified and the critical condition for the transformation of deformation mechanism and was established in the alloys with a fixed morphology of LPSO phase. For studying the effect of the LPSO phase with different morphologies, the grains with similar crystal orientation were selected and then the effect the LPSO phase with different morphologies on the activation different deformation mechanism was investigated and compared. What’s more, the mechanism of LPSO phase influencing the activation of deformation mechanism was revealed. Combined the effects of crystal orientation and the LPSO phase on the activation of deformation mechanism, the synergistic effect of LPSO phase and crystal orientation was explained and the crystal orientation dependence of deformation mechanism is established with consideration the influence of LPSO phase on deformation mechanism in this project. The achievements provide the experimental evidence and theoretical guidance for the design and optimization of texture and deformation process of rare earth magnesium alloys.

本项目以Mg-Gd-Y-Zn-Zr合金为研究对象，采用适当的热处理与塑性变形，获得具有不同LPSO相形态与初始晶体取向多晶样品。综合运用各种现代先进的微观组织观察和晶体取向测试分析技术，结合微观晶体塑性理论，开展LPSO相形态与晶体取向对合金变形机制的影响规律及作用机理研究。通过研究：探明具有固定LPSO相形态特征、不同初始晶体取向合金中主导变形机制，确定滑移、孪生及扭折相互竞争机制及其临界转变条件，揭示具有不同形态特征的LPSO相合金中变形机制的晶体取向相关性；分析具有特定晶体取向、不同形态特征的LPSO相样品中滑移、扭折及孪生变形机制启动的差异性，阐明LPSO相尺寸、体积分数及分布特征对合金不同变形机制启动的影响规律及作用机理。基于上述研究，探明LPSO相形态与晶体取向对变形机制的协同影响规律，阐明其相互作用机理。项目的完成将丰富镁合金塑性变形理论，同时为高强镁合金设计与制备提供参考。

项目以具有良好综合力学性能且LPSO相形态易于调控的Mg-Gd-Y-Zn-Zr合金为研究对象，同时将工作拓展至Mg-Zn-Gd/Y以及Mg-Gd-Y-Zr等系列合金，遵循材料成分-工艺-组织-性能相关性原理，通过适当的变形与热处理，获得具有不同LPSO相形态与初始晶体取向多晶样品。项目综合运用各种现代先进的微观组织观察和晶体取向测试分析技术，结合微观晶体塑性理论，系统研究了合金在轧制、锻造等过程中微观组织、晶体取向（织构）演变及力学性能变化规律，研究了具有固定形态特征LPSO相合金中变形机制的晶体取向相关性以及具有相似初始晶体取向（织构）合金中LPSO相形态对变形机制的影响规律，并将两者耦合影响有效进行剥离，探明了LPSO相形态与晶体取向对变形机制的协同影响规律，阐明了其相互作用机理；探究了LPSO相形态对合金再结晶行为的影响，从第二相影响再结晶晶界迁移以及孪晶体积分数的角度，阐明了LPSO相形态与再结晶分数的内在相关性；深入分析了“LPSO相+Mg基体+LPSO相”复合层状结构中的孪生行为，揭示了孪生难易程度与LPSO相片层间距的相关性以及具有不同片层间距镁基体中孪生机制的差异性；研究了变形与退火过程中孪晶内LPSO相分解及其晶体取向变化，分析了LPSO相分解对后续孪生变形的影响。项目的完成丰富了镁合金塑性变形理论，同时可为镁合金在航空航天、轨道交通等领域的实际应用提供参考。相关研究内容和结果在国内外学术期刊发表了标注有本项目资助的论文27篇（其中国外期刊24篇、国内期刊3篇；第一标注12篇，第二标注12篇、第四标注2篇、第5标注1篇），包括1篇《Acta Materialia》、3篇《Metallurgical and Materials Transactions A》、8篇《Materials Science and Engineering A》、5篇《Journal of Alloys and Compounds》、5篇《Materials Characterization》、2篇《Journal of Materials Engineering and Performance》，被SCI收录25篇。培养学位论文标注本项目资助的毕业博士生5名、硕士生4名。