Anomalous X-ray diffraction (AXRD) is a technique which makes use of effects occurring near the energy of an absorption edge of an element present in the studied sample. The intensity of the diffracted radiation exhibits an anomalous decrease when the primary beam energy matches the energy needed to excite an electron from an atomic orbital. The characteristics of this step are sensitive to the concentration of the `anomalous' element and its spatial distribution in the sample. In the present investigation, AXRD was employed to study ω particles in a metastable β titanium alloy Ti–15Mo (in wt%). The experiments were done in an energy range around the MoKedge at 20.0 keV, allowing investigation of the distribution of Mo in the material, which is rejected from the volume of ω particles during their diffusion-driven growth. This paper deals with diffuse scattering patterns around the (006)βdiffraction maximum. It was observed that different regions of the diffuse scattering exhibited different variations of diffracted intensity with the incident photon energy near the absorption edge. Numerical simulations of diffuse scattering patterns as well as of energy dependences of the scattered intensity were performed. It was found that the observed patterns and their dependence on the primary beam energy can be explained by taking into account (a) elastic deformation of the β matrix arising from the presence of slightly misfitting ω particles and (b) the presence of a `cloud' of a higher Mo concentration around ω particles.

中文翻译：

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β-Ti(Mo)单晶中ω纳米粒子的反常X射线衍射

反常 X 射线衍射 (AXRD) 是一种利用所研究样品中存在的元素吸收边能量附近发生的效应的技术。当主束能量与从原子轨道激发电子所需的能量匹配时，衍射辐射的强度表现出异常降低。此步骤的特征对“异常”元素的浓度及其在样品中的空间分布敏感。在本研究中，采用 AXRD 来研究亚稳态 β 钛合金 Ti-15Mo（重量％）中的 ω 粒子。实验是在 Mo 周围的能量范围内进行的K边缘在 20.0 keV，允许研究 Mo 在材料中的分布，在扩散驱动的生长过程中，Mo 被 ω 粒子的体积拒绝。本文讨论 (006) 周围的漫散射图案β衍射最大值。观察到漫散射的不同区域随着吸收边附近的入射光子能量表现出不同的衍射强度变化。对漫散射图案以及散射强度的能量依赖性进行了数值模拟。结果发现，观察到的图案及其对主光束能量的依赖性可以通过考虑以下因素来解释：A) 由于存在轻微失配的 ω 粒子而引起 β 矩阵的弹性变形，并且 (乙) ω 粒子周围存在较高 Mo 浓度的“云”。