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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ti(GaO2)4 by Materials Project

Ga4TiO8 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four equivalent GaO6 octahedra, corners with four equivalent GaO4 tetrahedra, and edges with two equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There is two shorter (1.94 Å) and four longer (2.00 Å) Ti–O bond length. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with two equivalent TiO6 octahedra, corners with five equivalent GaO6 octahedra, and corners with two equivalent GaO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–67°. There are a spread of Ga–O bond distances ranging from 1.84–1.90 Å. In the second Ga3+ site, Ga3+ is bonded to six O2- atoms to form GaO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with five equivalent GaO4 tetrahedra, and edges with four equivalent GaO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Ga–O bond distances ranging from 1.94–2.09 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Ga3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Ti4+ and one Ga3+ atom. In the third O2- site, O2- is bonded in a trigonal planar geometry to one Ti4+ and two equivalent Ga3+ atoms. In the fourth O2- site, O2- is bonded to four Ga3+ atoms to form a mixture of distorted edge and corner-sharing OGa4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(Ag4S3)2 by Materials Project

Ag8TiS6 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. Ti4+ is bonded to four S2- atoms to form TiS4 tetrahedra that share corners with two equivalent AgS4 tetrahedra and corners with two equivalent AgS4 trigonal pyramids. There are a spread of Ti–S bond distances ranging from 2.29–2.31 Å. There are eight inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.51–2.88 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.48–3.46 Å. In the third Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.54–2.75 Å. In the fourth Ag1+ site, Ag1+ is bonded to four S2- atoms to form distorted AgS4 trigonal pyramids that share corners with two equivalent TiS4 tetrahedra and corners with three equivalent AgS4 tetrahedra. There are a spread of Ag–S bond distances ranging from 2.59–2.80 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.55–3.20 Å. In the sixth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.56–3.29 Å. In the seventh Ag1+ site, Ag1+ is bonded to four S2- atoms to form distorted AgS4 tetrahedra that share corners with two equivalent TiS4 tetrahedra and corners with three equivalent AgS4 trigonal pyramids. There are a spread of Ag–S bond distances ranging from 2.62–2.72 Å. In the eighth Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to three S2- atoms. There are a spread of Ag–S bond distances ranging from 2.55–2.75 Å. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to eight Ag1+ atoms. In the second S2- site, S2- is bonded in a distorted trigonal bipyramidal geometry to one Ti4+ and four Ag1+ atoms. In the third S2- site, S2- is bonded in a 5-coordinate geometry to one Ti4+ and four Ag1+ atoms. In the fourth S2- site, S2- is bonded in a 6-coordinate geometry to six Ag1+ atoms. In the fifth S2- site, S2- is bonded in a 1-coordinate geometry to one Ti4+ and four Ag1+ atoms. In the sixth S2- site, S2- is bonded in a 4-coordinate geometry to one Ti4+ and three Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(SiO3)2 by Materials Project

TiSi2O6 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.84–2.17 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent TiO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–57°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent TiO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–59°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one Si4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ti4+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ti4+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(CrSe2)2 by Materials Project

TiCr2Se4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ti4+ is bonded to six Se2- atoms to form TiSe6 octahedra that share corners with twelve equivalent CrSe6 octahedra, edges with two equivalent TiSe6 octahedra, and faces with two equivalent CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are two shorter (2.58 Å) and four longer (2.63 Å) Ti–Se bond lengths. Cr2+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with six equivalent TiSe6 octahedra, edges with six equivalent CrSe6 octahedra, and a faceface with one TiSe6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Cr–Se bond distances ranging from 2.51–2.64 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Ti4+ and three equivalent Cr2+ atoms to form a mixture of distorted edge and corner-sharing SeTi2Cr3 trigonal bipyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Ti4+ and three equivalent Cr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(FeO2)2 by Materials Project

Fe2TiO4 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with two equivalent FeO5 square pyramids, edges with two equivalent TiO6 octahedra, edges with three equivalent FeO6 octahedra, and edges with two equivalent FeO5 square pyramids. The corner-sharing octahedra tilt angles range from 6–55°. There are a spread of Ti–O bond distances ranging from 1.90–2.09 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to five O2- atoms to form distorted FeO5 square pyramids that share corners with two equivalent TiO6 octahedra, corners with two equivalent FeO6 octahedra, edges with two equivalent TiO6 octahedra, edges with three equivalent FeO6 octahedra, and edges with two equivalent FeO5 square pyramids. The corner-sharing octahedra tilt angles range from 18–59°. There are a spread of Fe–O bond distances ranging from 2.11–2.29 Å. In the second Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent TiO6 octahedra, corners with two equivalent FeO5 square pyramids, edges with two equivalent FeO6 octahedra, edges with three equivalent TiO6 octahedra, and edges with three equivalent FeO5 square pyramids. The corner-sharing octahedra tilt angles range from 6–55°. There are a spread of Fe–O bond distances ranging from 2.13–2.23 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ti4+ and four Fe2+ atoms to form a mixture of edge and corner-sharing OTiFe4 square pyramids. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ti4+ and one Fe2+ atom. In the third O2- site, O2- is bonded to two equivalent Ti4+ and three Fe2+ atoms to form OTi2Fe3 square pyramids that share corners with two equivalent OTiFe4 square pyramids and edges with five OTi2Fe3 square pyramids. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ti4+ and three Fe2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(NCl3)2 by Materials Project

TiCl6N2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is zero-dimensional and consists of eight ammonia molecules and four TiCl6 clusters. In each TiCl6 cluster, Ti4+ is bonded in an octahedral geometry to six equivalent Cl1- atoms. All Ti–Cl bond lengths are 2.34 Å. Cl1- is bonded in a single-bond geometry to one Ti4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(FeO2)2 by Materials Project

Fe2TiO4 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent TiO6 octahedra, edges with two equivalent FeO6 octahedra, and edges with three equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 0–51°. There are a spread of Ti–O bond distances ranging from 1.96–2.08 Å. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.20 Å) and two longer (2.23 Å) Fe–O bond lengths. In the second Fe2+ site, Fe2+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Fe–O bond distances ranging from 2.06–2.72 Å. In the third Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with three equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 0–55°. There are a spread of Fe–O bond distances ranging from 1.97–2.22 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a square co-planar geometry to four equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a distorted square co-planar geometry to six Fe2+ atoms. In the third O2- site, O2- is bonded to two equivalent Ti4+ and two equivalent Fe2+ atoms to form distorted OTi2Fe2 tetrahedra that share corners with four equivalent OTi2Fe3 square pyramids, corners with two equivalent OTi2Fe2 tetrahedra, corners with six equivalent OTiFe4 trigonal bipyramids, and edges with two equivalent OTiFe4 trigonal bipyramids. In the fourth O2- site, O2- is bonded to four Fe2+ atoms to form OFe4 tetrahedra that share corners with six equivalent OTi2Fe3 square pyramids, corners with two equivalent OFe4 tetrahedra, corners with four equivalent OTiFe4 trigonal bipyramids, and edges with two equivalent OTi2Fe3 square pyramids. In the fifth O2- site, O2- is bonded to one Ti4+ and four Fe2+ atoms to form distorted OTiFe4 trigonal bipyramids that share corners with five OTi2Fe2 tetrahedra, corners with two equivalent OTiFe4 trigonal bipyramids, edges with two equivalent OTi2Fe3 square pyramids, an edgeedge with one OTi2Fe2 tetrahedra, and edges with three equivalent OTiFe4 trigonal bipyramids. In the sixth O2- site, O2- is bonded to two equivalent Ti4+ and three Fe2+ atoms to form distorted OTi2Fe3 square pyramids that share corners with two equivalent OTi2Fe3 square pyramids, corners with five OTi2Fe2 tetrahedra, edges with three equivalent OTi2Fe3 square pyramids, an edgeedge with one OFe4 tetrahedra, and edges with two equivalent OTiFe4 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(NF2)3 by Materials Project

TiNF6N2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight ammonia molecules and one TiNF6 framework. In the TiNF6 framework, Ti3+ is bonded to six equivalent F1- atoms to form TiF6 octahedra that share corners with six equivalent NF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Ti–F bond lengths are 1.91 Å. N1+ is bonded to six equivalent F1- atoms to form NF6 octahedra that share corners with six equivalent TiF6 octahedra. The corner-sharing octahedral tilt angles are 0°. All N–F bond lengths are 2.08 Å. F1- is bonded in a distorted linear geometry to one Ti3+ and one N1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Phase Identification in Synchrotron X-ray Diffraction Patterns of Ti–6Al–4V Using Computer Vision and Deep Learning

X-ray diffraction patterns contain information about the atomistic structure and microstructure (defect population) of materials, extracting detailed information from diffraction patterns is complex, demanding and relies on prior knowledge. Here, we hypothesize that deep-learning techniques can help to perform an effective and accurate analysis with high throughput rates. To demonstrate this concept, we applied a novel deep learning framework to determine the evolution of the β-phase volume fraction in a Ti–6Al–4V alloy during heat-treatment from video sequences of 2D diffraction patterns recorded in transmission and with highly monochromatic radiation in a synchrotron beamline. In particular, we studied the impact of network design on prediction reliability and computational performance. Networks of different architectures were trained using 3008 experimental 2D patterns. A well-tuned model was found to reproduce the phase fractions of another experimental data set, consisting of 1100 diffraction patterns, with a mean-square error as small as 2.6 x 10 -4 . The average prediction error of β-phase volume fraction was within 1.6 x 10 -2 (in each diffraction pattern) of the values obtained by conventional methods. Our work demonstrates that convolutional neural networks can evaluate high energy X-ray diffraction patterns with a remarkable level of reliability. Furthermore, it demonstrates the significance of network design on the reliability of predictions and computational performance. The most complex models do not necessarily result in highest accuracy and may even fail to learn from the data.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effect of heat treatment on the tensile behavior of selective laser melted Ti-6Al-4V by in situ X-ray characterization

Selective Laser Melted Ti-6Al-4V (as-SLMed) exhibits decreased yield strength, increased work hardening, and increased ductility after heat treatment at 730 degrees C (HT-730) or 900 degrees C (HT-900) for 2 h. To understand the change of mechanical properties, in situ high energy X-ray diffraction (HEXRD) is used to examine the phase composition, load partitioning, slip system activity, and dislocation density evolution in all three specimens. The as-SLMed specimen is dominated by martensitic α'. After heat treatment, α' partly or fully decomposes into α+β, reducing the yield strength. In HT-730, beta precipitates with confined size show much higher lattice strain than the α'/α matrix during deformation; in HT-900, the lattice strain difference is mostly eliminated. This is a key reason for the increased ductility in HT-900. From the anisotropic lattice strain development, basal slip is identified as the easiest slip system in α'/α. Using an elasto-plastic self-consistent (EPSC) model, the critical resolved shear stress ratio between prismatic slip and basal slip (CRSS prism /CRSS basal ) is estimated to be 1.31 and 1.16 in the as -SLMed and the HT-900 specimens, respectively. Further, the alpha phase in HT-900 is able to activate multiple slip systems and accumulate more dislocations during plastic deformation. This explains why HT-900 has better ductility and higher work hardening rate than the other two specimens.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Solidification texture, variant selection, and phase fraction in a spot-melt electron-beam powder bed fusion processed Ti-6Al-4V

The effect of a spot melt strategy on the solidification texture, variant selection, phase fraction, and their variations along the build height was investigated in comparison to a conventional linear melt strategy. Ti-6Al-4V alloy samples were manufactured by an electron-beam powder bed fusion process using two different melt strategies and characterized using high-energy synchrotron x-ray diffraction. The linear and spot melt cases resulted in β<100> cube and fiber textures, respectively, with the cube/fiber axis nearly parallel to the build direction. The α phase exhibited Burgers orientation relationship (BOR) with the parent β phase for both melt strategies. Although all of the key texture components and the BOR between the α and β phases were consistently observed in both cases along the build height, there were several measurable differences between the two. At the top of the build height, the β<100> build texture intensity was stronger in the linear case. However, the texture intensity in the linear case decreased gradually from the top to near the substrate, whereas the spot melt case did not show this trend. Moreover, the BOR was examined along the build height and the results showed that there is a distinct variant selection in the spot melt case, unlike the linear case. Specifically, the planar variants sharing ($\bar101$) β || (0002) α with [$\bar2\bar2\bar2$]β and [$2\bar22$]β were the most prominent in the spot melt, but no preference was identified in the directional variants. The β phase fraction was slightly lower in the spot melt case compared to the linear case. In both the cases, the β phase fraction decreased moving towards the substrate but remained significantly higher than that of the powder feedstock. Overall, the novel spot melt strategy produced a more homogeneous microstructure in terms of both the phase fraction and texture across the build height.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Predicting phase transformation kinetics during metal additive manufacturing using non-isothermal Johnson-Mehl-Avrami models: Application to Inconel 718 and Ti-6Al-4V

Here, a computational model was developed to predict solid-state phase transformation kinetics within mechanical parts during metal additive manufacturing processes. This model is a modified version of the Johnson-Mehl-Avrami model for non-isothermal phase transformations that can be applied to various material systems undergoing solid-state phase transformations. Using the thermal history of an additive manufacturing fabricated mechanical part, along with the necessary thermodynamic data and kinetic information as inputs, the model outputs the history of phase fraction evolution during the build process. The model was applied to an Inconel 718 part built by powder bed fusion and a Ti-6Al-4V part built by directed energy deposition. Microstructure characterization and mechanical testing were performed for the validation of the model.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Improving fatigue performance of additively manufactured Ti-6Al-4V using sulfur-based self-terminating etching processes

The adoption of Additively Manufactured (AM) Ti-6Al-4V (Ti64) is continually increasing in the industry due to its benefits over the conventional manufacturing techniques. However, AM Ti64 parts are prone to poor surface finish, which significantly affects their fatigue performance. Therefore, AM Ti64 parts need post-processing to enhance surface finish and fatigue performance. Prior work with a sulfur-based self-terminating etching process for AM Ti64 demonstrated support removal and surface roughness reduction. To further this work, this manuscript details the impact of this sulfur-based post-processing technique on the mechanical properties and the fatigue life of AM Ti64 by characterizing the surface roughness, microstructural evolution, and fracture surfaces. Finally, this post-processing technique decreased the surface roughness parameter - S v by 55 % from 84 ± 11 µm to 38 ± 19 µm and increased the average fatigue life by 340 % from about 7000 cycles to 30,000 cycles.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Enhanced biomechanical performance of additively manufactured Ti-6Al-4V bone plates

As the global trauma fixation devices market expands rapidly, it is imperative to improve the production of fixation devices through enhanced design accuracy and fit for best performance and maximum patient comfort. Selective laser melting (SLM) is one of the mature additive manufacturing methods, which provides a viable route for the rapid production of such devices. In this work, the ability of SLM to produce near-net-shape parts, as desired for medical implants, was utilized for the fabrication of bone plates from Ti-6Al-4V alloy powder. Martensitic microstructure obtained after the printing of alloy resulted in poor ductility, limiting its application in the field of orthopedics. A specially designed repeated cyclic heating and cooling close to but below the β-transus was used to transform from acicular to a bimodal microstructure without the need for plastic deformation prior to heat treatment for improving the ductility. Bone plates subjected to this heat treatment were mechanically tested by means of tensile and 3-point bend tests and demonstrated large improvement in ductility, and the values were comparable to those similar plates prepared from wrought alloy. Other important properties required for implants were assessed, such as corrosion resistance in simulated body fluid and cytocompatibility in vitro using MC3T3-E1 cells. These results for the bone plate after heat treatment were excellent and similar to those of the additively manufactured and wrought plates. Taken together, the performance of the additively manufactured bone plates after subjecting to heat treatment was similar to those of bone plate manufactured using wrought alloy. These results have important implications for the fabrication of patient-specific metallic orthopedic devices using SLM without compromising their biomechanical performance by subjecting them to a tailored heat treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Integrated top-down process and voxel-based microstructure modeling for Ti-6Al-4V in laser wire direct energy deposition process

Laser-wire metal additive manufacturing (AM) is one of the ideal direct energy deposition (DED) processes for creating large-scale parts with a medium level of complexity. However, the DED process involves complex thermal signatures and wide length scales making the fabrication of realistic AM components and part qualification often reliant on experimental trial-and-error optimization. While experimental measurements over the full volume of a part are valuable and necessary, measuring the entire area of a part is significantly laborious and practically infeasible, particularly for large parts in terms of cost and rapid qualification. Therefore, in this work, we developed an effective thermal and microstructure modeling framework based on the Johnson–Mehl-Avrami-Kolmogorov (JMAK) and Koistinen & Marburger (KM) models through a top-down approach that considers plate distortion-affected thermal profiles. A voxel-by-voxel simulation method is used to predict individual phase fractions of Ti-6Al-4 V. The predicted results were validated through detailed metallurgical measurements. A combined voxel-by-voxel approach with a sparse data reconstruction technique produced a near-perfect reconstruction of the original data. This approach anticipates a significant reduction in data points and computation time and resources. Lastly, we conclude with potential extensions of this work to other modeling efforts.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Sulfidation kinetics of titanium and Ti-6Al-4V with elemental sulfur

The sulfidation kinetics of titanium and Ti-6Al-4V (Ti64) using elemental sulfur were studied by measuring the amount of metal consumed instead of the change in mass or scale thickness. Here this metal consumption approach combines the parabolic oxidation law, Arrhenius equation, and Pilling-Bedworth ratio to determine the apparent activation energy and the pre-exponential factor of consumption of Ti64 during sulfidation. The estimations of apparent activation energy and pre-exponential factor were 110.4 kJ·mol -1 and 1.3×10 -9 m 2 s -1 for the titanium-sulfur, and 116.2 kJ·mol -1 and 1.2×10 -9 m2s -1 for the Ti64-sulfur system. Finally, a material removal predictor was developed to predict the amount of Ti64 consumed for a given sulfidation temperature and time.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Maximizing ion dynamics and electrochemical performance of ionic liquid-acetonitrile electrolyte in Ti 3 C 2 T x MXene

Modification of the structure and morphology of MXene electrodes and the formulation of the electrolytes used in their supercapacitor configurations are significant factors affecting the performance of electrochemical devices. In this study, we investigated the electrochemical performance and ion dynamics of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EmimTFSI], ionic liquid in the presence of acetonitrile (ACN) at different concentrations in Ti 3 C 2 T x MXene supercapacitor. We found an optimum concentration of ACN, at which more cations from the ionic liquid attach to the MXene electrode surface, providing higher electrochemical performance. This higher capacitance is also associated with increased microscopic dynamics of the cation away from the pore wall. These findings give a guideline to optimize the performance of MXene-based supercapacitors using organic solvents-ionic liquid-based electrolyte systems.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Federated learning for 2D synchrotron x-ray diffractometry: a cross-institutional approach for phase quantification of Ti–6Al–4V alloy

High-energy Two dimensional (2D) synchrotron x-ray diffractometry provides important insights into the atomistic structure and phase evolution of materials, yet traditional analysis methods remain complex, knowledge-intensive, and computationally demanding. Deep-learning models offer a powerful alternative for automating their analysis. Institutions that hold these datasets may be unwilling to share their data due to privacy and security policies, as well as the challenges associated with large-scale data transfer. As a result, models trained on local datasets often perform well only on their own data but exhibit bias and poor generalization across different instruments or facilities. To overcome these limitations, we explore federated learning (FL) for 2D synchrotron diffractograms, enabling collaborative model training without exchanging raw data. In this study, 2D synchrotron diffractograms of Ti–6Al–4V alloy collected from two independent facilities are used to train convolutional neural networks for predicting the β-phase volume fraction. Experimental results show that federated global models significantly outperform locally trained models in terms of generalization and achieve accuracy comparable to centralized trained models. These findings demonstrate the potential of FL to enable secure, cross-institutional collaboration and enhance the scalability of deep-learning-based materials characterization.

36 MATERIALS SCIENCE↗