Abstract It is well known that grain boundary sliding (GBS) provides stress concentration and initiates grain boundary fracture at the serrated grain boundary or grain triple junction during high-temperature creep. Recent reports on GBS occurring during deformation at room temperature suggest that stress concentration may occur due to GBS, which has a stress component parallel to the grain boundary plane, even in cold working. To identify if GBS can generate stress concentration and related defects at the grain boundary at room temperature, we experimentally investigated periodic defect formation along the serrated grain boundary during cold shear deformation. To obtain defect-free serrated grain boundary structure, optimal conditions of hot-torsion and annealing were determined. Cylindrical torsion specimens were then machined into notched tensile specimens, which provide the advantage of directly observing the GBS and lattice curvature. Extensive observations and orientation analysis on periodic defect formation along the serrated grain boundary suggest that GBS at room temperature can periodically nucleate twinning as well as dislocation arrays. Crystal plasticity simulation proved that serrated GB generates non-rotating region and split stress distribution with intensified value. Two stress concentration mechanisms during the accommodation of GBS at the serrated grain boundary were proposed: direct transfer from rotational stress and indirectly formed tensile component, namely “cleavage stress.” While direct energy transfer was likely to follow the local Schmid's law for direction of the grain rotation, cleavage accommodation represented geometrically necessary characteristics.

中文翻译：

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冷剪应变AZ31合金锯齿状晶界通过晶界滑动周期性形成变形孪晶和位错阵列

摘要 众所周知，晶界滑动（GBS）在高温蠕变过程中提供应力集中并在锯齿状晶界或三重晶界处引发晶界断裂。最近关于在室温下变形期间发生 GBS 的报告表明，即使在冷加工中，GBS 也可能发生应力集中，GBS 具有平行于晶界平面的应力分量。为了确定 GBS 是否可以在室温下在晶界处产生应力集中和相关缺陷，我们通过实验研究了冷剪切变形过程中沿锯齿状晶界的周期性缺陷形成。为了获得无缺陷的锯齿状晶界结构，确定了热扭转和退火的最佳条件。然后将圆柱扭转试样加工成缺口拉伸试样，这提供了直接观察 GBS 和晶格曲率的优势。对沿锯齿状晶界形成的周期性缺陷的广泛观察和取向分析表明，室温下的 GBS 可以周期性地使孪晶和位错阵列成核。晶体塑性模拟证明，锯齿状GB产生非旋转区和具有增强值的裂隙应力分布。提出了在锯齿状晶界处调节 GBS 过程中的两种应力集中机制：旋转应力的直接传递和间接形成的拉伸分量，即“解理应力”。虽然直接能量转移可能遵循局部施密德定律来确定晶粒旋转方向，