Abstract Understanding the effects of basal precipitates on plasticity is of scientific interest and practical importance in the development of high-strength magnesium alloys. In this study, compression experiments are carried out on solution-treated and aged Mg–9wt.% Al binary alloy single-crystal micropillars cut from large-grained polycrystalline samples. The samples are compressed in two different orientations ( and ) to examine the effects of basal-precipitates on extension twinning and pyramidal slip, respectively. In the solution-treated, precipitate-free, samples, the propagation and thickening of single twins dominates, while in the aged micropillars with Mg17Al12 basal-precipitates, multiple twins are observed suggesting a substantial increase in the stress required to propagate and thicken twins compared to nucleating twins. In addition, these basal precipitates are observed to be more effective than c-axis rod precipitates in Mg-Zn alloy in impeding twin growth for the studied volume fractions. In samples, the plate-like, Mg17Al12 precipitates are found to provide enormous strengthening under compression, compared to solution-treated samples, by hindering the motion of pyramidal dislocations. Further still, our comparative analysis suggests that pyramidal-slip/precipitate interactions, whether via bowing between or cutting precipitates, differ from one Mg alloy to another depending on the geometry and alignment of their precipitates. Our findings offer insights into how manipulating precipitation in the design and processing of Mg alloys can lead to superior mechanical properties.

中文翻译：

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基底沉淀对拉伸孪晶和锥体滑移的影响：镁铝二元合金的显微机械和电子显微镜研究

摘要 了解基础析出物对塑性的影响在高强度镁合金的开发中具有科学意义和实际意义。在这项研究中，对从大晶粒多晶样品切割的固溶处理和时效 Mg–9wt.% Al 二元合金单晶微柱进行了压缩实验。样品以两个不同的方向 ( 和 ) 压缩，以分别检查基底沉淀物对拉伸孪晶和金字塔滑移的影响。在固溶处理、无沉淀物的样品中，单孪晶的扩展和增厚占主导地位，而在具有 Mg17Al12 基础沉淀物的老化微柱中，观察到多孪晶，表明与相比，扩展和增厚孪晶所需的应力显着增加到成核双胞胎。此外，观察到这些基础沉淀物比 Mg-Zn 合金中的 c 轴棒状沉淀物更有效地阻止所研究体积分数的孪晶生长。在样品中，与固溶处理的样品相比，板状 Mg17Al12 析出物在压缩下提供了巨大的强化，通过阻碍锥体位错的运动。此外，我们的比较分析表明，锥体滑移/沉淀相互作用，无论是通过在沉淀之间弯曲还是切割沉淀，都因一种镁合金而异，具体取决于其沉淀物的几何形状和排列。我们的研究结果提供了有关如何在镁合金的设计和加工中操纵沉淀可以导致卓越的机械性能的见解。