Carlsen Mads, Malamud Florencia, Modregger Peter, Wildeis Anna, Hartmann Markus, Brandt Robert, Menzel Andreas, Liebi Marianne
Paul Scherrer Institut 5232 Villigen PSI Switzerland.
Physics Department University of Siegen 57072Siegen Germany.
J Appl Crystallogr. 2025 Mar 13;58(Pt 2):484-494. doi: 10.1107/S1600576725001426. eCollection 2025 Apr 1.
We demonstrate an approach to the reconstruction of scanning probe X-ray diffraction tomography data with anisotropic polycrystalline samples. The method involves reconstructing a voxel map containing an orientation distribution function in each voxel of a bulk 3D sample. By choosing a particular kind of basis functions, we can effectively utilize non-negativity in orientation space for samples with sparse texture. This enables us to achieve stable solutions at high angular resolutions where the problem would otherwise be underdetermined. This method differs from established approaches by not relying on a peak-finding step. It is therefore applicable to sample systems consisting of small and highly mosaic crystalline domains that are not handled well by these methods. We demonstrate the new approach using data from a shot-peened martensite sample where we are able to map the twinning microstructure in the interior of a bulk sample without resolving the individual lattice domains. We also demonstrate the approach on a piece of gastropod shell with a mosaic microstructure. The results suggest that, by utilizing the sparsity of the texture, the experiment can be carried out using only a single rotation axis, unlike previous demonstrations of texture and tensor tomography.
我们展示了一种用于重建具有各向异性多晶样品的扫描探针X射线衍射断层扫描数据的方法。该方法涉及重建一个体素图，该体素图在一个三维大块样品的每个体素中都包含一个取向分布函数。通过选择一种特定类型的基函数，对于具有稀疏织构的样品，我们可以有效地利用取向空间中的非负性。这使我们能够在高角分辨率下获得稳定的解，否则该问题将是欠定的。该方法与现有方法的不同之处在于不依赖于峰值查找步骤。因此，它适用于由小的且高度镶嵌的晶域组成的样品系统，而这些方法对这些样品系统处理得不好。我们使用来自喷丸马氏体样品的数据展示了这种新方法，在该样品中我们能够绘制出大块样品内部的孪晶微观结构，而无需分辨单个晶格域。我们还在具有镶嵌微观结构的腹足类贝壳上展示了该方法。结果表明，与之前的织构和张量断层扫描演示不同，通过利用织构的稀疏性，该实验仅使用单个旋转轴即可进行。
