Ludwig W, Reischig P, King A, Herbig M, Lauridsen E M, Johnson G, Marrow T J, Buffière J Y
Université de Lyon, INSA-Lyon, MATEIS CNRS UMR 5510, 69621Villeurbanne, France.
Rev Sci Instrum. 2009 Mar;80(3):033905. doi: 10.1063/1.3100200.
X-ray diffraction contrast tomography (DCT) is a technique for mapping grain shape and orientation in plastically undeformed polycrystals. In this paper, we describe a modified DCT data acquisition strategy which permits the incorporation of an innovative Friedel pair method for analyzing diffraction data. Diffraction spots are acquired during a 360 degrees rotation of the sample and are analyzed in terms of the Friedel pairs ((hkl) and (hkl) reflections, observed 180 degrees apart in rotation). The resulting increase in the accuracy with which the diffraction vectors are determined allows the use of improved algorithms for grain indexing (assigning diffraction spots to the grains from which they arise) and reconstruction. The accuracy of the resulting grain maps is quantified with reference to synchrotron microtomography data for a specimen made from a beta titanium system in which a second phase can be precipitated at grain boundaries, thereby revealing the grain shapes. The simple changes introduced to the DCT methodology are equally applicable to other variants of grain mapping.
X射线衍射对比断层扫描（DCT）是一种用于绘制塑性未变形多晶体中晶粒形状和取向的技术。在本文中，我们描述了一种改进的DCT数据采集策略，该策略允许采用一种创新的弗里德尔对方法来分析衍射数据。在样品360度旋转过程中采集衍射斑点，并根据弗里德尔对（（hkl）和（hkl）反射，在旋转中相隔180度观察到）进行分析。由此确定衍射矢量的精度提高，使得能够使用改进的算法进行晶粒索引（将衍射斑点分配到产生它们的晶粒）和重建。所得晶粒图的精度通过参考同步加速器显微断层扫描数据进行量化，该数据来自一个由β钛系统制成的样品，其中第二相可以在晶界处析出，从而揭示晶粒形状。引入到DCT方法中的简单变化同样适用于晶粒映射的其他变体。
