Abstract Weak subdivision or fragmentation ability of deformed {100} ( // ND, normal direction) grains by traditional unidirectional (symmetric) rolling results in uneven deformation during tantalum (Ta) processing. Thus, a recently developed asymmetric cross rolling (ACR) is adopted in this work to enhance the subdivision of {100} grain in Ta sheets. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and Vickers hardness (HV) were used for the characterisation of microstructure in deformed {100} grains. It is shown that added shear strain component in the ACR leads to heterogeneous deformation substructures within {100} grains. The increase of speed ratio in ACR further enhances the subdivision of deformed {100} grains and thus increases the density of geometrically necessary dislocations (GNDs) in them. The computation of the largest Schmid factor (SFrolling) along with Taylor model suggests that the ACR promotes easier slip within deformed {100} grains. Therefore, the necessary total shear strain contributing to the increase of GNDs density is small. By contrast, the shear strain accumulated after CR-1.0 is distributed more evenly in each slip system resulting in rather sparse distribution of dislocation lines.

中文翻译：

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通过非对称交叉轧制增强高纯钽板中{100}晶粒的细分

摘要 传统单向（对称）轧制对变形{100}（//ND，法向）晶粒的弱细分或破碎能力导致钽（Ta）加工过程中变形不均匀。因此，在这项工作中采用了最近开发的非对称交叉轧制 (ACR) 来增强 Ta 片中 {100} 晶粒的细分。电子背散射衍射 (EBSD)、透射电子显微镜 (TEM) 和维氏硬度 (HV) 用于表征变形 {100} 晶粒的微观结构。结果表明，在 ACR 中添加的剪切应变分量会导致 {100} 晶粒内的异质变形子结构。ACR 中速度比的增加进一步增强了变形 {100} 晶粒的细分，从而增加了其中几何必要位错 (GND) 的密度。最大施密德因子 (SFrolling) 和泰勒模型的计算表明，ACR 促进变形 {100} 晶粒内更容易滑动。因此，有助于增加 GND 密度的必要总剪切应变很小。相比之下，CR-1.0 后积累的剪切应变在每个滑移系统中分布更均匀，导致位错线分布相当稀疏。