Fang Haixing, Ludwig Wolfgang
European Synchrotron Radiation Facility 71 Avenue des Martyrs Grenoble 38000 France.
Université de Lyon INSA Lyon, CNRS MATEIS Villeurbanne 69621 France.
J Appl Crystallogr. 2025 May 12;58(Pt 3):796-812. doi: 10.1107/S160057672500250X. eCollection 2025 Jun 1.
To extend the applicability of synchrotron diffraction contrast tomography (DCT) towards more plastically deformed materials, we have developed a forward-model-based reconstruction method. This allows us to reconstruct grain shapes and local orientations in materials exhibiting levels of intragranular orientation spread that can no longer be handled with the conventional Friedel-pair-based indexing and tomographic reconstruction approach. This method consists of seed and regional indexing, in which an exhaustive searching and fitting of orientations is first performed to index the seed orientation, and then a regional indexing by testing a list of local orientations around the seed orientation is carried out to maximize the completeness. The capability of this novel method was benchmarked and compared with reconstructions based on the conventional Friedel-pair-matching and tomographic reconstruction method using samples made from fully recrystallized Al-Cu alloy, moderately deformed α-Ti alloy and 10% creep-ruptured Fe-Au alloy. The results show that this method has the potential to overcome the deformation constraint and can reconstruct reasonably well the intragranular orientations. It is also suitable for multi-phase reconstruction and both box-beam and line-beam acquisition geometries. The implementation has been made flexible to support the use of single or multiple GPU machines. The strengths and weaknesses of the current forward-model-based reconstruction are discussed in detail with respect to the conventional Friedel-pair-matching method. To fully exploit and complement the strengths of the two methods, the code to implement the current forward-model-based reconstruction has been fully integrated with the existing DCT code and is open source for beamline data processing.
为了将同步辐射衍射对比断层扫描（DCT）的适用性扩展到更多塑性变形材料，我们开发了一种基于正向模型的重建方法。这使我们能够在具有晶内取向散布水平的材料中重建晶粒形状和局部取向，而这些材料已无法用传统的基于弗里德尔对的索引和断层重建方法处理。该方法由种子索引和区域索引组成，其中首先对种子取向进行详尽的取向搜索和拟合以进行索引，然后通过测试种子取向周围的局部取向列表进行区域索引以最大化完整性。使用由完全再结晶的Al-Cu合金、适度变形的α-Ti合金和10%蠕变断裂的Fe-Au合金制成的样品，对这种新方法的能力进行了基准测试，并与基于传统弗里德尔对匹配和断层重建方法的重建结果进行了比较。结果表明，该方法有潜力克服变形限制，并能较好地重建晶内取向。它也适用于多相重建以及盒形束和线束采集几何结构。该实现方式具有灵活性，支持使用单台或多台GPU机器。相对于传统的弗里德尔对匹配方法，详细讨论了当前基于正向模型的重建的优缺点。为了充分利用和补充这两种方法的优势，实现当前基于正向模型的重建的代码已与现有的DCT代码完全集成，并且作为束线数据处理的开源代码。
