Analysis of Strain, Stress and Texture with Quantum Beams, 2nd Edition

Welcome to the Special Issue of Quantum Beam Science, entitled “Analysis of Strain, Stress and Texture with Quantum Beams, 2nd Edition”. The closest international conference to this title is the International Conference on Mechanical Stress Evaluation by Neutron and Synchrotron Radiation (MECASENS). The 9th MECASENS was held from 19 to 21 September 2017 at Skukuza Rest Camp, South Africa [1,2]. The next MECASENS was scheduled to be held in Prague, the Czech Republic, in 2019, but preparations were delayed and it was postponed to 2020. Unfortunately, as you know, the COVID-19 pandemic occurred in 2020. The 10th MECASENS was held on-site and virtually in Prague from 25 to 27 November 2021 [3]. In Japan, domestic and international travel was strictly restricted, and experiments at synchrotron radiation facilities and neutron facilities were also restricted. On the other hand, in 2011, the accident occurred at the Fukushima Daiichi Nuclear Power Plant due to the tsunami caused by the Great East Japan Earthquake, and not only were all nuclear power plants across Japan shut down, but so was the research reactor JRR-3. The JRR-3 finally resumed operation in April 2022.

Due to the above circumstances, experiments using quantum beams to analyze stress, strain, and texture have been restricted, and international exchange has stagnated. This was the most difficult time for quantum beam research. However, even in this difficult situation in Japan, research has continued steadily. This Special Issue can be seen as evidence of that.

Suspension plasma sprayed thermal barrier coatings (SPS-TBCs) have a columnar microstructure, and are therefore expected to have excellent heat cycle and thermal shock resistance [4,5]. However, no investigation has been conducted to evaluate the internal stress distribution in SPS-TBCs with a columnar microstructure. In the Special Issue, the mechanism behind the excellent heat cycle resistance of SPS-TBCs was elucidated using synchrotron radiation and laboratory X-rays [6]. In this experiment, the residual stress was measured using a constant penetration depth method proposed by Ganzel [7,8], and its effectiveness was demonstrated.

A three-dimensional X-ray diffraction (3DXRD) is an excellent X-ray microscope that can measure the shape, orientation, and even strain of crystal grains [9,10,11,12,13]. However, the 3DXRD is limited in the number of crystals and sample dimensions. A noteworthy study has overcome these limitations by incorporating a rotating spiral slit into the scanning 3DXRD technique [14].

Previously, a slit system has been used to create a gauge volume in the bulk material for strain measurement using an area detector [15,16,17]. As a result, the experiment required a great deal of effort, such as making complex slits and adjustment of the optical system. In this Special Issue, an ingenious method for easily measuring strain in bulk materials is proposed using the area detector without the slit-system [18]. This is the double exposure method (DEM), and it is notable for its applicability to strain measurements in bulk materials, and it has been used to create stress maps of coarse grains and welds.

In crystalline materials with large crystal anisotropy, the stress–strain relationship varies greatly depending on the crystal orientation with plastic deformation. In order to investigate the stress–strain behavior of the lattice planes of a polycrystalline material, it is necessary to measure the elastic–plastic behavior of many diffraction planes. It is well known that intergranular strain is formed as a result of plastic anisotropy [19,20,21]. Using J-PARC [22], SNS [23], etc., many $\left(hkl\right)$ diffraction peaks can be measured by measuring spallation neutrons with time-of-flight (TOF). Therefore, the TOF is suitable for studying the deformation characteristics of crystalline materials.

Magnesium is the lightest metal in practical use and has the highest specific strength, so it is expected to be used in a wide range of fields. However, it is known that dislocations in magnesium alloys have a strong tendency to slip along their basal planes, resulting in very strong anisotropy of plastic deformation and poor ductility [24,25]. Although studies have been performed on its crystalline elastic–plastic behavior, many aspects remain unclear [26,27]. In HCP-structure magnesium alloys, the increase in lattice strain relative to true stress varies greatly between [$hk.l$] grains; so, in order to obtain true stress, a method has been proposed in which the volume fraction of each grain is weighted using many [$hk.l$] orientations, and the diffraction elastic constant is multiplied. The lattice strain value evaluated from the 12.1 peak shows a good linear relationship with the applied true stress for the whole deformation region [28].

There are also other interesting papers, such as the following, which I highly recommend you read:

• Nishida, M.; Harjo, S.; Kawasaki, T.; Yamashita, T.; Gong, W. Neutron Stress Measurement of W/Ti Composite in Cryogenic Temperatures Using Time-of-Flight Method. Quantum Beam Sci. 2023, 7, 8. https://doi.org/10.3390/qubs7010008
• Yamazaki, Y.; Shinomiya, K.; Okumura, T.; Suzuki, K.; Shobu, T.; Nakamura, Y. Relationship between Internal Stress Distribution and Microstructure in a Suspension-Sprayed Thermal Barrier Coating with a Columnar Structure. Quantum Beam Sci. 2023, 7, 14. https://doi.org/10.3390/qubs7020014
• Yasue, A.; Kawakami, M.; Kobayashi, K.; Kim, J.; Miyazu, Y.; Nishio, Y.; Mukai, T.; Morooka, S.; Kanematsu, M. Accuracy of Measuring Rebar Strain in Concrete Using a Diffractometer for Residual Stress Analysis. Quantum Beam Sci. 2024, 8, 7. https://doi.org/10.3390/qubs7020015
• Hayashi, Y.; Setoyama, D.; Fukuda, K.; Okuda, K.; Katayama, N.; Kimura H. Scanning Three-Dimensional X-ray Diffraction Microscopy with a Spiral Slit. Quantum Beam Sci. 2023, 7, 16. https://doi.org/10.3390/qubs7020016
• Hayashi, Y.; Kimura H. Scanning Three-Dimensional X-ray Diffraction Microscopy for Carbon Steels. Quantum Beam Sci. 2023, 7, 23. https://doi.org/10.3390/qubs7030023
• Harjo, S.; Gong. W.; Kawasaki, T. Stress Evaluation Method by Neutron Diffraction for HCP-Structured Magnesium Alloy. Quantum Beam Sci. 2023, 7, 32. https://doi.org/10.3390/qubs7040032
• Machiya, S.; Osamura, K.; Hishinuma, Y.; Taniguchi, H.; Harjo, S.; Kawasaki, T. Measurement of Mechanical Behavior of ¹¹B-Enriched ${\mathrm{MgB}}_2$ Wire Using a Pulsed Neutron Source. Quantum Beam Sci. 2023, 7, 34. https://doi.org/10.3390/qubs7040034
• Miura, Y.; Suzuki, K.; Morooka, S.; Shobu, T. Stress Measurement of Stainless Steel Piping Welds by Complementary Use of High-Energy Synchrotron X-rays and Neutrons. Quantum Beam Sci. 2024, 8, 1. https://doi.org/10.3390/qubs8010001
• Xu, P.; Zhang, S.; Harjo, S.; Vogel, S.C.; Tomoda, Y. Principal Preferred Orientation Evaluation of Steel Materials Using Time-of-Flight Neutron Diffraction. Quantum Beam Sci. 2024, 8, 7. https://doi.org/10.3390/qubs8010007