The tension-compression asymmetry presents notable challenges for the application of magnesium alloys in many fields. In this study, the solid-solution treated Mg-8.5Gd-4.5Y-0.8Zn-0.4Zr alloy's tension-compression asymmetry was examined using optical microscope (OM), x-ray diffraction (XRD), viscoplastic self-consistent (VPSC) modeling, and electron backscatter diffraction (EBSD). The VPSC hardening parameters were significantly adjusted based on the Schmid factor of deformation modes in rare earth magnesium (Mg-RE) alloy, which came from the EBSD data. Excellent agreement was found between the modified VPSC model's calculation results, especially the stress-strain curves and pole figures. The alloy exhibited good strength with a negligible tension-compression asymmetry and an impressive 0.98 ratio of compressive yield strength to tensile yield strength (CYS/TYS). The main cause could be attributed to the unusual texture of (11-20) <0001> in alloy, which eliminated the imbalance in tension and compression deformation by having a negative effect on the activation of {10-12} twinning in tensile and a positive effect in compressive deformation. The activation level of {10-12} twinning was 0.37 and 0.40 calculated by VPSC model, in the plastic deformation of tension and compression, respectively; in the tensile and compression samples, the EBSD data indicated that approximately 31.9% and 31.1% (area proportion) of the grains were deformed with twins, respectively. Both tension and compression deformation showed the {10-12} twinning in the early stage of deformation, which transformed to {11-22} twinning in the later stage. The considerable activation of pyramidal <c+a> during the later stages of deformation endowed the alloy with good ductility.

中文翻译：

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粘塑性自洽建模中异常织构对 Mg-RE 合金拉压不对称性的影响


拉压不对称性为镁合金在许多领域的应用带来了显著的挑战。本研究采用光学显微镜 （OM）、X 射线衍射 （XRD）、粘塑性自洽 （VPSC） 建模和电子背散射衍射 （EBSD） 研究了固溶体处理的 Mg-8.5Gd-4.5Y-0.8Zn-0.4Zr 合金的拉伸-压缩不对称性。VPSC 硬化参数根据来自 EBSD 数据的稀土镁 （Mg-RE） 合金变形模式的 Schmid 因子进行了显著调整。修正后的 VPSC 模型的计算结果，尤其是应力-应变曲线和极图之间有极好的一致性。该合金具有良好的强度，拉伸-压缩不对称性可以忽略不计，压缩屈服强度与拉伸屈服强度 （CYS/TYS） 之比为 0.98，令人印象深刻。主要原因可归因于合金中 （11-20） <0001> 的不寻常织构，它通过对拉伸中 {10-12} 孪晶的激活产生负面影响，对压缩变形产生积极影响，消除了拉伸和压缩变形的不平衡。VPSC 模型计算的 {10-12} 孪晶的活化水平分别为 0.37 和 0.40，分别在拉伸和压缩的塑性变形中;在拉伸和压缩样品中，EBSD 数据表明，分别约有 31.9% 和 31.1% 的晶粒（面积比例）与孪晶发生变形。拉压变形在变形初期表现为{10-12}孪晶，后期转变为{11-22}孪晶。在变形后期，金字塔形 <c+a> 的显著活化赋予了合金良好的延展性。