Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

Abstract

This paper presents a series of experiments to characterize the performance of the new IMAT beamline at the ISIS pulsed neutron source and provides examples to showcase the potential applications of Bragg-edge transmission imaging on the instrument. The characterization includes determination of the IMAT spectral and spatial resolutions through calibration measurements, and also determination of the precision and the accuracy of Bragg-edge analysis for lattice parameters of ceramics, metals and textured engineering alloys through high-temperature measurements. A novel Bragg-edge analysis method based on the cross-correlation of different Bragg edges has been developed to provide an estimate of the change in lattice parameter, which is especially useful for measurements of textured samples. Three different applications of the Braggedge transmission imaging technique are presented, including strain mapping, texture mapping and obtaining crystallographic information, i.e. the dependence on temperature of the Debye-Waller factor. The experimental results demonstrate the ability of the IMAT beamline to provide accurate strain measurements with uncertainties as low as 90 m" with reasonable measurement time, while characteristic materials parameters can be mapped across the sample with a spatial resolution of 300-600 mm for a strain map and down to $90 mm for a texture map.

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

“…The TOF tomography experiment was carried out at the IMAT beamline at the ISIS pulsed spallation source of the Rutherford Appleton Laboratory in the UK (Minniti et al, 2018;Ramadhan et al, 2019). TOF radiographs were taken for 251 projections uniformly distributed over a 360 tomographic range.…”

“…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).…”

Bragg Edge Analysis for Transmission Imaging Experiments software tool: BEATRIX

“…The software can be provided on request without warranty of any kind by the author. BEATRIX has already been used in several scientific computer programs studies (Vitucci et al, 2018;Kockelmann et al, 2018;Ramadhan et al, 2019), and this manuscript provides a reference and a useful introduction to the capabilities of this software tool.…”

“…Further development will be undertaken by the author to fully integrate Windows OS, making the software a cross-platform code. BEATRIX has already been used in a number of scientific studies (Vitucci et al, 2018;Kockelmann et al, 2018;Reid et al, 2018;Ramadhan et al, 2019), and this manuscript provides a useful introduction to the capabilities of this software tool. Moreover, a short illustration of BEATRIX is provided here for a typical data analysis of an energy-resolved imaging experiment.…”

“…As a result of the strong coherent elastic scattering interaction for thermal and cold neutrons, the measured transmission pattern contains important information about the crystalline state of the specimen. In particular, precise determination of the positions of Bragg edges provides a measure of lattice parameters (Santisteban et al, 2001(Santisteban et al, , 2002aSantisteban, 2005;Malamud & Santisteban, 2016;Tremsin et al, 2016;Ramadhan et al, 2018Ramadhan et al, , 2019Reid et al, 2018), while the heights of these edges give information about phase volume fractions (Steuwer et al, 2005;Woracek et al, 2014) and texture effects (Kockelmann et al, 2007;Santisteban et al, 2012;Malamud et al, 2014;Sato et al, 2017). The neutron wavelength shown in equation 3is a variable that is not directly measurable, and its value is usually determined at a pulsed neutron source via determination of the time of flight (TOF) for neutrons propagating at constant velocity along the instrument flight path.…”