ADVANCED MATERIALS & PROCESSES | JANUARY 2026 16 the [001] crystallographic direction. The pole figures generated from EBSD and XRD for both materials are shown in Fig. 1. While there is strong corre- spondence between the two sets of pole figures, slight differences are most likely due to the area sampled. Not only was the collection area different (~1.5 cm2 for XRD and ~1 mm2 for EBSD), but this also meant that the number of grains sampled was greatly different between the two methods. The XRD data area is more representative of the whole sample texture, in contrast to extremely localized texture gathered from EBSD. This finding is supported by the stronger texture hot-spots in the XRD-derived pole figures for the ODS sample in Fig. 1b as compared to the EBSD-derived pole figures, owing to the higher sampling statistics for the XRD data. The phase identification results of these samples revealed that the non-ODS samples consisted of only a single gamma phase while the ODS material had the gamma phase along with the dispersed oxide phase and a chromium carbide phase. The low volume percent of these additional components meant that these phases’ orientations did not appear distinctly in the XRD texture pole figures. These phases would, however, likely have impacted the EBSD pole figures due to their relative concentration in the smaller sample size of the EBSD scan. This accentuates a strength in EBSD data in highlighting minor phases that would not stand out in the bulk acquisitions that contribute to XRD data. The agreement between EBSD and XRD data support that the EBSD data is representative of the bulk and that the XRD data did not miss significant factors either. Conclusion. For this study, XRD was used to identify phases and investigate texture in the ODS and non-ODS AM superalloy samples. EBSD, as well as energy dispersive spectroscopy, was employed to investigate crystal orientation and to identify phases in these samples. Both methods showed random orientation in non-ODS samples, and some significant texture in the ODS samples. This strong agreement serves as self-validation for the two methods. The EBSD data were collected from a much smaller area than the XRD data, but the similar pole figures indicate that the EBSD was representative of the bulk sample and the XRD did not omit any significant phases. Another compelling insight from the comparison of these two methods’ data is that small carbide phases found within the SEM were significant but were in small quantity such that they were not a major factor in the XRD results. If the EBSD had been from an area within the sample exhibiting disproportionate amounts of the carbide phase, it would have had a higher influence on the EBSD pole figures. Having the XRD data from a much larger sample spot helps indicate the trace amount of the carbide phase within the bulk of the material. CASE STUDY 2: PHASE IDENTIFICATION FOR MINERAL SAMPLES Introduction. Understanding the radio frequency (RF) properties of a material is of concern to multiple projects at NASA Glenn Research Center, especially regarding signal propagation across non-Earth landscapes. Rather than spend energy developing a lunar simulant material with suitable mineralogical properties, candidate substitute materials to investigate RF properties of lunar soils were found in Nevada, USA. The Nevada National Security Site (NNSS) is a secure government area northwest of Las Vegas where nuclear arms were tested, thus making it a suspected good geologic analogue to lunar soils, however specific properties of the soil are not publicly available. Two soil samples were gathered from within this locality, one from within the crater of a 1960s nuclear test, and another from a nearby planned but never detonated test site. The task was to determine mineralogy of the soils selected to represent the RF properties of lunar soils. Methods. The samples, as-received, contained rocks and sand-sized particles. To prepare samples for XRD, the sand-sized material was separated by particle size using sieves. Screening resulted in three samples for each of the two sample localities, with particle sizes of < 180 µm, 180-595 µm, and > 595 µm. These samples were then milled with yttria-stabilized zirconium media, suspended in ethanol for five minutes each, and dispersed onto a zero-background silicon holder. The samples were then analyzed in a Bruker D8 Advanced diffractometer, from 5° to 120° 2θ with a step size of 0.02°, and 1 second per step. The instrument’s divergence slit was set to 0.3, used a Cu Kα filament, Bragg-Brentano focusing, and a linear position-sensitive Lynxeye detector. The data were analyzed using MDI Jade and PDF 2024. For EBSD, samples of the sandsized particles along with a few rocks were mounted in epoxy and then metallographically prepared and finished with a vibratory polish using 0.05 µm colloidal silica. The EBSD was collected on an Oxford Symmetry detector on a JEOL IT710 HR SEM using 20 kV and a probe current of 60-75; the maps were collected with a 70.6 ms frame time, with 5 frame averaging, gain of 2, image size of 1244 x 1024 pixels, and at 150× magni- fication. The Phase Identification tool in the Oxford AzTec software was used in conjunction with the American Mineralogist EBSD database. Results and Discussion. The EBSD maps were collected from multiple locations on the samples. The results showed that samples consisted of the following minerals: feldspars like anorthoclase, albite, and anorthite; quartz; muscovite and biotite micas; natrolite; and titanomagnetite. These phases were identified in at least one EBSD map taken throughout the samples. A representative EBSD map is shown in Fig. 2. This map shows multiple phases, with good confidence. Much of the matrix area around the grains showed zero solutions, which can be largely attributed to the data collection step size being larger than the grains within the matrix. There was some mis-indexing when it came to the feldspar grains. These grains had areas identified as anorthite and others as
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