Abstract
This article presents a measurement technique and data analysis tool to perform 3D grain distribution mapping and indexing of oligocrystalline samples using neutrons: Laue three-dimensional neutron diffraction (Laue3DND). The approach builds on forward modelling used for correlation and multiple fitting of the measured diffraction spots relative to individual grains. This enables not only to identify individual grains, but also their position and orientation in the sample. The feasibility and performance of the Laue3DND approach are tested using multi-grain synthetic datasets from cubic (α-Fe) and tetragonal (YBaCuFeO5) symmetries. Next, experimental results from two data sets measured at the FALCON instrument of Helmholtz-Zentrum Berlin are presented: A cylindrical alpha iron (α-Fe) reference sample with 5 mm diameter and 5 mm height, as well as a 2 mm3 layered perovskite (YBaCuFeO5). Using Laue3DND, we were able to retrieve the position and orientation of 97 out of 100 grains from a synthetic α-Fe data set, as well as 24 and 9 grains respectively from the α-Fe and YBaCuFeO5 sample measured at FALCON. Results from the synthetic tests also indicate that Laue3DND is capable of indexing 10 out of 10 grains for both symmetries in two extreme scenarios: using only 6 Laue projections and using 360 projections with extremely noisy data. The precision achieved in terms of spatial and orientation resolution for the current version of the method is 430 μm and 1° respectively. Based on these results obtained, we are confident to present a tool that expands the capabilities of standard Laue diffraction, providing the number, position, orientation and relative size of grains in oligocrystalline samples.
Highlights
Understanding the link between a material structure at different length scales and its emerging macroscopic properties is a general theme of material science
The experiments presented in this work were performed at the E11 beam port of Helmholtz-Zentrum Berlin (HZB) with the FALCON15 Laue diffractometer installed
The reason is foremost that the process for thresholding from the logarithm of the assignments will inevitably disregard some of the valid but not well fitted spots and secondly, that larger grains will generate more visible diffraction spots than smaller ones
Summary
Understanding the link between a material structure at different length scales and its emerging macroscopic properties is a general theme of material science. In the field of solid-state physics, a 3D grain mapping characterization tool with neutrons enables the utilization of imperfect crystals for diffraction studies, (e.g.) by providing 3D information about the position of the largest grain within a sample so it can be cut out. In both metallurgy and solid-state physics, neutrons are better suited than X-rays for in-situ testing with bulkier sample environments. Once the Laue patterns can be simulated, the solver is introduced and structured in seeding, single grain fitting and global fitting These are the set of iterative algorithms implemented to find the best possible match between the simulated and measured spots. The results obtained, the current performance of the method and the future challenges and improvements are laid out in the discussion and conclusions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
