研究目的
To visualize the three-dimensional B2 antiphase-domain structure in an annealed iron-rich Fe-Al alloy crystal using Bragg ptychography on two different reflections, (001) and (002), to separate phase domains and lattice displacement.
研究成果
The study successfully visualized the three-dimensional B2 antiphase-domain structure in an annealed iron-rich Fe-Al alloy crystal. Bragg ptychography performed on two different reflections allowed for the separation of phase domains and lattice displacement for the first time. The ADBs predominantly align with {110} planes, and there is a strong correlation between general lattice strain and the location of the domain wall, particularly when it is not parallel to a {110} plane.
研究不足
The resolution of the ptychography experiment was not sufficient to determine the exact size of an antiphase domain boundary (ADB). The possibility of performing longer acquisitions is challenged by the nanometer stability required in Bragg ptychography on multiple reflections.
1：Experimental Design and Method Selection:
Bragg ptychography was used to image the phase ordering in a Fe55Al45 alloy. The experiment involved measuring coherent x-ray diffraction patterns at both the (001) superlattice and (002) fundamental reflections to separate the effects of antiphase domain boundaries and lattice strain.
2：Sample Selection and Data Sources:
A Fe55Al45 alloy sample was grown and annealed to stabilize the ordered B2 phase. The sample was mounted on a goniometer and oriented with respect to the Bragg reflections.
3：List of Experimental Equipment and Materials:
The experiment utilized a partially coherent 7 keV x-ray beam focused by a Fresnel zone plate, with the diffracted intensity measured by a MAXIPIX pixel detector. The sample was a disk-shaped bulk crystal of Fe55Al
4：Experimental Procedures and Operational Workflow:
Ptychographic 3D data sets were measured by scanning the sample in three dimensions (two translations and one angular rotation) and recording the diffraction patterns at each position.
5：Data Analysis Methods:
The data were analyzed using a GPU-based algorithm to reconstruct 3D images of the sample's electron density and phase, with specific attention to separating the contributions from antiphase domains and lattice strain.
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