Abstract Plastic strain induced grain boundary migration (SIBM) is investigated by means of in-situ SEM experiments and AFM surface observations in the case of 4N pure aluminum. The study focuses on two polycrystalline samples obtained through different thermo-mechanical treatments that provide different initial (grain size and orientation) microstructures with different evolutions during heating. A total of 77 grain boundaries (GBs) were characterized from both samples. Evaluation of GB displacements was allowed by determining fixed points on initial and final EBSD maps and marks from thermal grooving along GB contours. Some sub-surface final examinations ensured the surface ones being pretty well representative of the bulk behaviour. The GB displacements were related to their geometry and to their initially available migration driving force P , the two main contributions of which were estimated. The boundary curvature contribution P c is estimated from SEM observations and the so-called "stored energy" contribution P Δ ρ (that results from the differential of dislocation densities Δ ρ across the boundary) is estimated using a crystal plasticity modeling within a homogenization scheme for aggregates validated on slip trace identifications from AFM observations. The resulting driving force P , related to the GB velocity V through the widely used law V = M P is compared with the observed displacement during a finite annealing time. Additional effects as thermal grooving and triple junction pinning or pulling are also discussed from complementary SEM and AFM observations of some typical GBs. Some evidences of GB out-of-plane displacements possibly contributing to the migration process are also commented. The quite extensive set of data regarding grain orientation, GB misorientation and curvature, intracrystalline slip activity and evolution during heating constitutes references for future comparisons with mesoscale simulations.

中文翻译：

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纯铝中塑性应变诱导晶界迁移 (SIBM)：SEM 原位和 AFM 检测

摘要 通过原位 SEM 实验和 AFM 表面观察，研究了 4N 纯铝的塑性应变诱导晶界迁移 (SIBM)。该研究的重点是通过不同的热机械处理获得的两个多晶样品，这些样品提供不同的初始（晶粒尺寸和取向）微观结构，在加热过程中具有不同的演变。从两个样品中表征了总共 77 个晶界 (GB)。通过确定初始和最终 EBSD 地图上的固定点以及沿 GB 轮廓的热开槽标记，可以评估 GB 位移。一些次表面的最终检查确保表面的能够很好地代表整体行为。GB 位移与其几何形状和最初可用的迁移驱动力 P 相关，估计了其中的两个主要贡献。边界曲率贡献 P c 是根据 SEM 观察估计的，所谓的“存储能量”贡献 P Δ ρ（由跨边界的位错密度 Δ ρ 差异产生）是使用均质化方案中的晶体塑性模型估计的用于通过 AFM 观察的滑动痕迹识别验证的聚集体。通过广泛使用的定律 V = MP 与 GB 速度 V 相关的最终驱动力 P 与在有限退火时间内观察到的位移进行比较。还从一些典型 GB 的互补 SEM 和 AFM 观察中讨论了其他影响，如热开槽和三结钉扎或拉动。还评论了可能有助于迁移过程的 GB 平面外位移的一些证据。关于晶粒取向、GB 错误取向和曲率、晶内滑移活动和加热过程中演化的大量数据构成了未来与中尺度模拟进行比较的参考。