Revealing 3D intragranular micromechanical fields at triple junctions
Revealing 3D intragranular micromechanical fields at triple junctions
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DOI：
10.1016/j.actamat.2023.119300
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发表时间：
2023-08
期刊：
影响因子：
9.4
通讯作者：
Sven E. Gustafson;W. Ludwig;Raquel Rodríguez-Lamas;C. Yildirim;K. Shanks;C. Detlefs;M. Sangid
中科院分区：
文献类型：
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作者：
Sven E. Gustafson;W. Ludwig;Raquel Rodríguez-Lamas;C. Yildirim;K. Shanks;C. Detlefs;M. Sangid
三结点，即多晶固体中三个或多个晶粒的交叉点，是潜在应力集中和应变局部化的已知位置。在这项工作中，晶内晶格曲率和弹性应变测量通过一种新的放大风格的同步辐射X射线技术相结合的三重结。此外，这项工作重新访问的影响，包括弹性应变梯度，同时计算内嵌入晶粒通过奈位错张量的位错密度。在没有弹性应变梯度的情况下，位错密度在热点处被低估了最大位错密度值的27%。三重结附近的空间区域被发现包含最高值的晶内取向差度量和一般较高的值比晶界（两个晶粒之间）。沿沿着单个三重连接线在晶粒内测量晶内取向差、弹性应变和位错密度的不均匀分布，并且三重连接线端点（四重点）表现出基本上不同的微观力学场。这项工作提供了一个独特的三维视图的三重结内的个别晶粒和突出的空间异质性沿沿着三重结线的晶内微观力学响应，特别是当比较相对不那么复杂的行为沿着晶界。虽然晶粒平均的例子提供了跨晶粒的晶间应变，几个例子的晶内应变附近的三重连接可视化。晶内晶格曲率（与应变度量）和弹性应变（与应力）的组合分析提供了一个更完整的表征比以前报道的3D亚晶粒领域。
Triple junctions, intersections of three or more grains in polycrystalline solids, are known locations of potential stress concentration and strain localization. In this work, intragranular lattice curvatures and elastic strains are measured at triple junctions via a novel zoom-in style combination of synchrotron X-ray techniques. Additionally, this work revisits the impact of including elastic strain gradients while calculating the dislocation density within embedded grains via the Nye dislocation tensor. Without elastic strain gradients, the dislocation density is underestimated at a hotspot by 27% of the maximum dislocation density value. Spatial regions near triple junctions are found to contain both the highest values of the intragranular misorientations metrics and generally higher values than grain boundaries (between two grains). A heterogenous distribution of intragranular misorientation, elastic strain, and dislocation density is measured within a grain along a single triple junction line, and the triple junction line end points (quad points) exhibit substantially different micromechanical fields. This work provides a unique 3D view of triple junctions within individual grains and highlights their spatially heterogenous intragranular micromechanical response along triple junction lines, especially when compared to relatively less complex behavior along grain boundaries. While a grain averaged example is provided of intergranular strain across grains, several examples of intragranular strain were visualized near a triple junction. The combined analysis of intragranular lattice curvature (associated with strain metrics) and elastic strain (associated with stress) provides a more complete characterization of the 3D sub-grain fields than previously reported.