Coherent precipitation of ordered phases is responsible for providing exceptional high‐temperature mechanical properties in a wide range of compositionally complex alloys. Ordered phases are also essential to enhance the magnetic or catalytic properties of alloyed nanoparticles. The present work aims to demonstrate the relevance of Bragg coherent diffraction imaging (BCDI) for studying bulk and thin‐film samples or isolated nanoparticles containing coherent nanoprecipitates/ordered phases. The structures of crystals of a few tens of nanometres in size are modelled with realistic interatomic potentials and are relaxed after introduction of coherent ordered nanoprecipitates. Diffraction patterns from fundamental and superstructure reflections are calculated in the kinematic approximation and used as input to retrieve the strain fields using algorithmic inversion. First, the case of single nanoprecipitates is tackled and it is shown that the strain field distribution from the ordered phase is retrieved very accurately. Then, the influence of the order parameter S on the strain field retrieved from the superstructure reflections is investigated. A very accurate strain distribution can be retrieved for partially ordered phases with large and inhomogeneous strains. Subsequently, the relevance of BCDI is evaluated for the study of systems containing many precipitates, and it is demonstrated that the technique is relevant for such systems. Finally, the experimental feasibility of using BCDI to image ordered phases is discussed in the light of the new possibilities offered by fourth‐generation synchrotron sources.

中文翻译：

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纳米沉淀物的布拉格相干成像：超结构反射的作用

有序相的连贯沉淀可为多种成分复杂的合金提供出色的高温机械性能。有序相对于增强合金化纳米颗粒的磁性或催化性能也是必不可少的。本工作旨在证明布拉格相干衍射成像（BCDI）与研究体相和薄膜样品或包含相干纳米沉淀/有序相的分离的纳米颗粒的相关性。用现实的原子间电势对几十纳米大小的晶体结构进行建模，并在引入相干有序纳米沉淀后将其放宽。在运动学近似中计算了来自基本反射和上层结构反射的衍射图样，并用作通过算法反演来检索应变场的输入。首先，解决了单个纳米沉淀物的情况，结果表明，从有序相中获得的应变场分布非常准确。然后，订单参数的影响研究了从上部结构反射中获得的应变场上的S。对于具有大且不均匀应变的部分有序相，可以获取非常准确的应变分布。随后，对BCDI的相关性进行了评估，以研究包含许多沉淀物的系统，并证明该技术与此类系统相关。最后，根据第四代同步加速器源提供的新可能性，讨论了使用BCDI对有序相进行成像的实验可行性。