Coupling between creep and redox behavior in nickel - yttria stabilized zirconia observed in-situ by monochromatic neutron imaging

Abstract

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Bragg-edge attenuation spectra at voxel level from 4D wavelength-resolved neutron tomography

“…Bragg-edge neutron transmission is emerging as a powerful technique to study in a nondestructive way the microstructural information of crystalline materials (Santisteban et al, 2002a;Woracek et al, 2018), such as phase (Steuwer et al, 2004(Steuwer et al, , 2005Woracek et al, 2014;Makowska et al, 2015Makowska et al, , 2016Makowska et al, , 2017Vitucci et al, 2018), texture (Santisteban et al, 2006(Santisteban et al, , 2012 and stress state (Santisteban et al, 2001(Santisteban et al, , 2002bSteuwer et al, 2001Steuwer et al, , 2003Abbey et al, 2009;Woracek et al, 2011;Strobl et al, 2012;Iwase et al, 2012;Wensrich et al, 2016a,b;Hendriks et al, 2017;Brooks et al, 2018;Ramadhan et al, 2019). With the time-offlight (TOF) method, it is possible to compute the spatially resolved wavelength-dependent transmission and in principle the total cross section of a sample (Kockelmann et al, 2007;Lehmann et al, 2009) for each pixel position of a TOF imaging detector (Tremsin et al, 2015).…”

“…Transmission spectra of polycrystalline materials, such as most metals, exhibit in the thermal and cold neutron energies specific patterns characterized by well defined and sudden increases of transmitted intensity (Bragg edges), due to coherent elastic scattering of neutrons with wavelength at specific hkl lattice planes with inter-planar distance d. According to Bragg's law, = 2d hkl sin , the Bragg edges occur when = 2d hkl , that is when the scattering angle (2) is equal to 180 , because beyond that wavelength no further Bragg scattering can take place at these specific lattice planes. Therefore, analysis of the shape and position of the Bragg edges allows quantitative characterization of the crystallographic properties of a specimen (Sato, Wavelength-selective neutron tomography can enhance the contrast between different materials or phases of the same material, for example, by selecting a specific range or a limited set of a few different wavelengths from the incident neutron spectrum (Kardjilov et al, 2003(Kardjilov et al, , 2004Treimer et al, 2006;Woracek et al, 2014;Makowska et al, 2015Makowska et al, , 2017. With the option of wavelength-resolved tomographic scanning, some crystallographic properties of a studied material (e.g.…”

Modeling cooperative creep reoxidation effect on the mechanical stability of anode-supported solid oxide fuel cell

“…When disregarding cracking of cell, the predict curvature (Figure ) is qualitatively validated against the experiment observation of Malzbender et al with good agreement. However, the curvature of the full reoxidized state in this study is not expected to revert to bending towards anode when compared to Malzbender et al Indeed, the reoxidation process commonly accompanies with complicated changes in local structure and behavior, such as possible electrolyte cracking, anode stiffness decrease caused by microcracks, and accelerated creep during reoxidation which are ignored in our model. It is important to exactly predict the changes of curvature during oxidation for the structural stability of the SOFC stacks, because the excessive curvature is reported to impede stack assembly and current collection .…”

Frame overlap Bragg edge imaging

“…Likewise, recording a wavelength dependent attenuation spectrum in this case implies to scan through wavelengths measuring images for consecutive wavelengths one after the other. While for some applications only a few wavelengths need to be probed and the wavelength resolution of velocity selectors ( ) or conventional crystal monochromators ( of a few ) is sufficient 3 , 4 , 10 , for several applications a higher wavelength resolution ( ) is required and probing a significant wavelength range of a few Ångströms quasi-simultaneously is advantageous. In the latter case, which includes key applications such as strain mapping 6 , 7 , 12 , 13 , time resolved investigations such as phase transformation studies 14 , 15 but also multi-phase identification and mapping, a Time-of-Flight (ToF) approach is the method of choice.…”

“…Neutron Bragg edge imaging 1 has proven to be a powerful tool for the non-destructive characterization of materials with regards to spatially resolved assessment of crystalline characteristics such as crystalline phase distributions [2][3][4][5] , strain fields [6][7][8] and texture features 9,10 . In contrast to X-rays, neutrons are able to probe the volume of bulk engineering materials and in contrast to neutron diffraction, Bragg edge imaging can provide superior spatial resolution.…”