Origins of high ductility exhibited by an extruded magnesium alloy Mg-1.8Zn-0.2Ca: Experiments and crystal plasticity modeling
Origins of high ductility exhibited by an extruded magnesium alloy Mg-1.8Zn-0.2Ca: Experiments and crystal plasticity modeling
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挤压镁合金 Mg-1.8Zn-0.2Ca 表现出高延展性的起源：实验和晶体塑性建模
DOI：
10.1016/j.jmst.2020.12.047
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发表时间：
2021
影响因子：
10.9
通讯作者：
Knezevic Marko
中科院分区：
文献类型：
--
作者：
Wang Jie;Zhu Gaoming;Wang Leyun;Vasilev Evgenii;Park Jun-Sang;Sha Gang;Zeng Xiaoqin;Knezevic Marko
塑性和强度低是制约镁合金广泛应用的主要瓶颈。本文系统地设计了一种低合金Mg-Zn-Ca合金的成分和制备工艺，表明该合金可以在低温（~ 250 ℃）和高速（~ 2 mm/s）下挤压。在挤压之后，该合金表现出显著弱化的基底织构、相对小的晶粒尺寸、非常高的拉伸伸长率（约30%）和良好的强度。使用三维原子探针断层扫描（3D-APT），透射电子显微镜（TEM），电子背散射衍射（EBSD）结合表面滑移痕迹分析，原位同步辐射X射线衍射和弹塑性自洽（EPSC）建模的组合，大大提高了延展性的起源进行了研究。观察到Zn和Ca原子在晶界处的共偏析，并且与织构弱化和晶界介导的塑性相关，这两者都提高了延展性。虽然基底滑移和棱柱滑移被确定为合金中的主要变形系统，但它们的滑移阻力之间的比率相对于纯Mg和大多数其它Mg合金显著降低，显著有助于合金的改善的延展性。该Mg-Zn-Ca合金具有优异的力学性能和较低的制造成本，是一种有希望的工业化生产的候选合金。
Low ductility and strength are major bottlenecks against Mg alloys’ wide applications. In this work, we systematically design the composition and fabrication process for a low-alloyed Mg-Zn-Ca alloy, showing that it can be extruded at low temperatures (∼250 ℃) and high speeds (∼2 mm/s). After the extrusion, this alloy exhibits a substantially weakened basal texture, relatively small grain size, very high tensile elongation (∼30%), and good strength. The origin of the considerably improved ductility was studied using a combination of three-dimensional atom probe tomography (3D-APT), transmission electron microscopy (TEM), electron backscattered diffraction (EBSD) in conjunction with surface slip trace analysis, in-situ synchrotron X-ray diffraction, and elasto-plastic self-consistent (EPSC) modeling. Co-segregation of Zn and Ca atoms at a grain boundary is observed and associated with texture weakening and grain boundary mediated plasticity, both improving the ductility. While basal slip and prismatic slip are identified as the dominant deformation systems in the alloy, the ratio between their slip resistances is substantially reduced relative to pure Mg and most other Mg alloys, significantly contributing to the improved ductility of the alloy. This Mg-Zn-Ca alloy exhibiting excellent mechanical properties and low fabrication cost is a promising candidate for industrial productions.