tensile testing in a scanning electron microscope (SEM) in conjunction with high-resolution electron backscatter diffraction (HR-EBSD) under load was used to characterize the evolution of geometrically necessary dislocation (GND) densities at individual grain boundaries as a function of applied strain in a polycrystalline Mg4Al alloy. The increase in GND density was investigated at plastic strains of 0 %, 0.6 %, 2.2 %, 3.3 % from the area including 76 grains and correlated with (i) geometric compatibility between slip systems across grain boundaries, and (ii) plastic incompatibility. We develop expressions for the grain boundary GND density evolution as a function of plastic strain and plastic incompatibility, from which uniaxial tensile stress-strain response of polycrystalline Mg4Al are computed and compared with experimental measurement. The findings in this study contribute to understanding the mechanisms governing the strain hardening response of single-phase polycrystalline alloys and more reliable prediction of mechanical behaviors in diverse microstructures.

中文翻译：

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使用扫描电子显微镜和 HR-EBSD 中的原位拉伸测试量化晶界对多晶 Mg[sbnd]4Al 几何必要位错密度演化和应变硬化的影响


使用扫描电子显微镜 (SEM) 中的拉伸测试与负载下的高分辨率电子背散射衍射 (HR-EBSD) 来表征各个晶界处的几何必要位错 (GND) 密度随施加应变的变化在多晶 Mg4Al 合金中。在包括 76 个晶粒的区域中，研究了塑性应变为 0%、0.6%、2.2%、3.3% 时 GND 密度的增加，并与 (i) 跨晶界滑移系统之间的几何相容性和 (ii) 塑性不相容性相关。我们开发了晶界 GND 密度演变作为塑性应变和塑性不相容性函数的表达式，从中计算多晶 Mg4Al 的单轴拉伸应力-应变响应，并与实验测量进行比较。这项研究的结果有助于理解控制单相多晶合金应变硬化响应的机制，并更可靠地预测不同微观结构中的机械行为。