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NASA NTRS2002

Application of Powder Diffraction Methods to the Analysis of the Atomic Structure of Nanocrystals: The Concept of the Apparent Lattice Parameter (ALP)

The applicability of standard methods of elaboration of powder diffraction data for determination of the structure of nano-size crystallites is analysed. Based on our theoretical calculations of powder diffraction data we show, that the assumption of the infinite crystal lattice for nanocrystals smaller than 20 nm in size is not justified. Application of conventional tools developed for elaboration of powder diffraction data, like the Rietveld method, may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter' (alp) is introduced. We assume a model of nanocrystal having a grain core with well-defined crystal structure, surrounded by a surface shell with the atomic structure similar to that of the core but being under a strain (compressive or tensile). The two structural components, the core and the shell, form essentially a composite crystal with interfering, inseparable diffraction properties. Because the structure of such a nanocrystal is not uniform, it defies the basic definitions of an unambiguous crystallographic phase. Consequently, a set of lattice parameters used for characterization of simple crystal phases is insufficient for a proper description of the complex structure of nanocrystals. We developed a method of evaluation of powder diffraction data of nanocrystals, which refers to a core-shell model and is based on the 'apparent lattice parameter' methodology. For a given diffraction pattem, the alp values are calculated for every individual Bragg reflection. For nanocrystals the alp values depend on the diffraction vector Q. By modeling different a0tomic structures of nanocrystals and calculating theoretically corresponding diffraction patterns using the Debye functions we showed, that alp-Q plots show characteristic shapes which can be used for evaluation of the atomic structure of the core-shell system. We show, that using a simple model of a nanocrystal with spherical shape and centro-symmetric strain at the surface shell we obtain theoretical alp-Q values which match very well the alp-Q plots determined experimentally for Sic, GaN, and diamond nanopowders. The theoretical models are defined by the lattice parameter of the grain core, thickness of the surface shell, and the magnitude and distribution of the strain field in the surface shell. According to our calculations, the part of the diffraction pattern measured at relatively low diffraction vectors Q (below 10/angstrom) provides information on the surface strain, whle determination of the lattice parameters in the grain core requires measurements at large Q-values (above 15 - 20/angstrom).

Palosz, B.↗

DOE OSTI2022

Correlating Crystallography, Magnetism, and Electronic Structure Across Anhysteretic First-Order Phase Transition in Pr 2 In

Here, temperature-dependent powder X-ray diffraction and magnetization measurements of Pr 2 In conclusively prove that the unusual anhysteretic first-order paramagnetic-ferromagnetic phase transition in the compound is related to concurrent changes in both the magnetic and crystallographic lattices. At the same time, the hexagonal Ni 2 In-type structure is stable at least between 6 and 298 K, including at T C = ~57 K. From the density functional theory calculations, the electronic structure of the compound is extraordinarily sensitive to minor changes in lattice parameters that occur across the phase transition, revealing the origin of strong magnetoelastic coupling. In the vicinity of T C , the maximum entropy change, ΔS Max = -16 J Kg -1 K -1 induced by a moderate magnetic field change of 20 kOe (ΔS Max = -20 J Kg -1 K -1 for 50 kOe magnetic field change) is comparable to other known potentially functional materials demonstrating large cryogenic magnetocaloric effect.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Imaging of voltage-controlled switching of magnetization in highly magnetostrictive epitaxial Fe–Ga microstructures

The magnetoelectric behavior of epitaxial Fe–Ga microstructures on top of a (001)-oriented PMN–PT piezoelectric substrate is imaged with magnetic X-ray microscopy. Additionally, the micron-scale strain distribution in PMN–PT is characterized by X-ray microdiffraction and examined with respect to the results of the Fe–Ga magnetoelectric switching. The magnetic reorientation of Fe–Ga is found to be strongly correlated with size, shape, and crystallographic orientation of the microstructures. In the case of square-shaped structures, size dictates the influence of the strain distribution on both the initialization of the ground state and on the magnetic reorientation during application of voltage. On the other hand, elliptical microstructures demonstrate completely different magnetic responses depending on the relative orientation of their long axis with respect to the crystallographic directions of the PMN–PT. This study demonstrates that engineering the behavior of highly magnetostrictive epitaxial microdevices is possible. It further elucidates that voltage-induced actuation can be largely tuned to achieve the desired type of magnetic switching ranging from vortex circulation reversal, domain wall motion, to a large rotation of magnetization. Because of the outstanding properties of the investigated material system, the reported findings are expected to be of great interest for the realization of next-generation energy-efficient magnetic memory and logic devices.

42 ENGINEERING↗

DOE OSTI2022

Ethylene polymerization with a crystallographically well-defined metal–organic framework supported catalyst

The inherent crystallinity of metal–organic framework (MOF) catalysts offers the possibility to understand the structure of the active site at the molecular level. This property is often lacking in traditional amorphous supports. Cr-SIM-NU-1000, a MOF-supported Cr 3+ heterogeneous catalyst, is shown to be competent for ethylene polymerization after activation with AlEt 2 Cl (DEAC), producing crystalline linear polyethylene (PE). The polymer produced has a low polydispersity (D = 2.0), in marked contrast to the Phillips supported chromium catalyst, Cr@SiO 2 (D ~ 8–65). Cr-SIM-NU-1000 achieves a turnover frequency of 2.6 × 10 3 h –1 under 40 bar ethylene pressure at room temperature, with corresponding PE productivity of 1.3 × 10 5 g PE mol –1 Cr per h. Single crystal X-ray diffraction (SC-XRD) of the pre-catalyst was conducted by collecting a structure of alkyl aluminum (DEAC) co-catalyst treated Cr-SIM-NU-1000. This crystal structure provides insight into the interactions between DEAC co-catalyst and Cr active site, revealing a Cr–C bond after treatment with DEAC. Furthermore, DEAC is crystallographically resolved at the terminal oxy-ligands of the node and likely also exists within the window pores of the framework between nodes, based on electron density mapping. Cr-SIM-NU-1000 offers the opportunity to study a structurally well-defined olefin polymerization system, with atomically precise characterization of the pre-catalyst structure. Furthermore, this allows the proposal of a mechanism and feeds into future development of next-generation heterogeneous catalyst systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Imitation of spin density wave order in Cu 3 Nb 2 O 8

Spin density waves, based on modulated local moments, are usually associated with metallic materials, but have recently been reported in insulators which display coupled magnetic and structural order parameters. Here, we discuss one such example, the multiferroic Cu 3 Nb 2 O 8 , which is reported to undergo two magnetic phase transitions, first to an unknown antiferromagnetic phase at $T_N$ ≈ 26.5 K , and then to a helicoidal structure coupled to an electric polarization below $T_2$ ≈ 24 K which breaks the crystallographic inversion symmetry. By analogy with other complex oxides, one might naturally expect this intermediate phase to be a spin density wave phase. We apply spherical polarimetry to confirm the low-temperature magnetic structure, yet only observe a single magnetic phase transition to helicoidal order. We argue that the reported unknown phase actually supports an imitation spin density wave which originates from a decoupling of the components of the magnetic order parameter, as allowed by symmetry and driven by thermal fluctuations. This provides a mechanism for the magnetic, but not nuclear, structure to break inversion symmetry thereby creating an intermediate phase in the proximity of $T_N$ which imitates a spin density wave. As the temperature is reduced, this intermediate structure destabilizes the crystal such that a structural chirality is induced, as reflected by the emergence of the electric polarization, and the imitation spin density wave relaxes into a generic helicoid. This scenario in which critical fluctuations allow the magnetic structure to break inversion symmetry while the crystal structure remains centrosymmetric might be relevant to other complex multiferroics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1988

The Cyclic Stress-Strain Behavior of a Single Crystal Nickel-Base Superalloy

The cyclic stress-strain response and similar deformation structures of the single crystal nickel based superalloy was described under a specific set of conditions. The isothermal low cycle fatigue response and deformation structures were described at a typical intermediate temperature and at high temperature. Specimens oriented near the (001) and (111) crystallographic orientations were tested at 1050 C, where more moderate orientation effects were expected. This enabled the description of the deformation structures at each of the 2 temperatures and their relationship to the observed cyclic stress-strain behavior. The initial yield strength of all specimens tested at 650 C was controlled by the shearing of the gamma prime precipitates by dislocation pairs. Low cycle fatigue tests at 650 C had cyclic hardening, which was associated with dislocation interactions in the gamma matrix. The initial yield strength of specimens tested at 1050 C was associated with dislocation bypassing of the gamma prime precipitates. Low cycle fatigue tests at 1050 C had cyclic softening, associated with extensive dislocation recovery at the gamma-gamma prime interfaces along with some gamma prime precipitate coarsening.

Gabb, Timothy P.↗

DOE OSTI2025

Crystallographic Snapshots of Pre- and Post-Lanthanide Halide Hydrolysis─Reaction Products Captured by the 4-Amino-1,2,4-triazole Ligand

Reactions of lanthanide(III) chloride salts with 4-amino-1,2,4-triazole (4-NH 2 -1,2,4-Triaz) in azole melts have led to the isolation of both hydrolysis and non-hydrolysis products in the same synthesis with the inclusion of a variety of ligands, anions, and water, allowing us to capture crystallographic snapshots of different forms and intermediate hydrolysis fragments. The structural studies reported here include anhydrous and hydrated nonhydrolyzed complexes which were isolated alongside hydrolysis products giving oxide/hydroxide lanthanide(III) dimers, tetramers, and ultimately hexamers. The compounds isolated include [Nd 2 Cl 6 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 (4-NH 2 -1,2,4-Triaz) 2 ], [Ce 2 Cl 4 (μ 2 -Cl) 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 ] n , [Ce 2 (µ 2 -Cl) 4 (µ 2 -OH) 2 (µ 2 -4-NH 2 -1,2,4-Triaz) 2 ] n , [Ln 4 Cl 4 (µ 2 -Cl) 4 (µ 3 -OH) 4 (µ 2 -4-NH 2 -1,2,4-Triaz) 4 ] n •2nH 2 O (Ln = Ce, Nd), and [Ce 6 Cl 6 (µ 6 -O 0.5 )(µ 3 -Cl 0.5 ) 4 (µ 3 -Cl 0.75 ) 3 (µ 3 -OH) 0.75 (µ 2 -4-NH 2 -1,2,4-Triaz) 12 ((OH 2 ) 0.25 ) 2 ] 2 [CeCl 6 ][Cl 9 ]•xH 2 O. In all complexes all lanthanide atoms are pairwise connected via one or more 4-NH2-1,2,4-Triaz ligands and sometimes additional Cl - anions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Topology driven and soft phonon mode enabled Na-ion diffusion in quaternary chalcogenides, Na 3 ZnGaX 4 (X = S, and Se)

The compounds Na 3 ZnGaX 4 (X = S, Se) are potential solid electrolyte materials in sodium-based batteries, which have certain advantages over oxide materials and have shown significant ionic conductivity at ambient temperature. In this paper, we bring out atomic-level features of the diffusion process in these new materials using the microscopic techniques of inelastic neutron scattering (INS), quasielastic neutron scattering (QENS), and ab initio molecular dynamics (AIMD) simulations. The insights obtained from these techniques are unique and not available from other macroscopic experiments. Neutron scattering experiments have been performed at temperatures from 100 to 700 K. The simulations have been carried out up to 900 K. We have calculated the phonon spectra and the space–time correlation functions and found good agreement with the results of the neutron scattering experiments. The simulations enable detailed analysis of the atomic-site dependent dynamical information. We observe low-energy phonon modes of ~6 meV involving the vibrations of certain Na atoms in the lattice. This reveals that the Na at 32g Wyckoff sites (Na2) has sufficiently shallow potential among the two available crystallographic sites. This shallow potential facilitates diffusion. Furthermore, the specific structural topology of the network of interconnected zig-zag chains of the Na2 atomic sites provides the low-barrier energy pathways for diffusion. A small fraction of vacancy defects appears essential for diffusion. We further observe that the Na2 atoms undergo jump-like diffusion to the vacant next or the 2nd next neighbour sites at ~4 Å. While the QENS experiments reveal the jump-like diffusion and its time scale, detailed analysis of the AIMD simulations shows that the jumps appear mostly along zig-zag chains of the Na2 sites in the tetragonal ab-plane, as well as between the chains along the c-axis. In conclusion, the net diffusion is essentially 3-dimensional, with little anisotropy despite the anisotropy of the tetragonal crystal structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Dislocation half-loop control for optimal V-defect density in GaN-based light emitting diodes

V-defects are morphological defects that typically form on threading dislocations during epitaxial growth of $(0001)$-oriented GaN layers. A V-defect is a hexagonal pyramid-shaped depression with six {$10\bar{1}1$}-oriented sidewalls. These semipolar sidewalls have a lower polarization barrier than the polarization barriers present between the polar c-plane quantum wells and quantum barriers and can laterally inject carriers directly into quantum wells in GaN-based light emitting diodes (LEDs). This is especially important, as the high polarization field in c-plane GaN is a significant factor in the high forward voltage of GaN LEDs. The optimal V-defect density for efficient lateral carrier injection in a GaN LED (∼10 9 cm −2 ) is typically an order of magnitude higher than the threading dislocation density of GaN grown on patterned sapphire substrates (∼10 8 cm −2 ). Pure-edge dislocation loops have been known to exist in GaN, and their formation into large V-defects via low-temperature growth with high Si-doping has recently been studied. Here, in this work, we develop a method for pure-edge threading dislocation half-loop formation and density control via disilane flow, growth temperature, and thickness of the half-loop generation layer. We also develop a method of forming the threading dislocation half-loops into V-defects of comparable size to those originating from substrate threading dislocations.

Crystallographic defects↗

DOE OSTI2026

Crystallographic registry in epitaxial V3O5 thin films

Crystallographic orientation plays a central role in determining transport properties in correlated oxides with low-hysteresis metal–insulator transitions. Here, V3O5 thin films were grown on Al2O3 (0001) and their crystallographic registry was evaluated using x-ray diffraction and cross-sectional transmission electron microscopy. θ–2θ measurements show a single out-of-plane orientation defined by the (202) reflection. Azimuthal φ-scans of the V3O5 (310) reflection exhibit twelve discrete maxima over 360°, indicating a finite set of in-plane orientations imposed by the substrate symmetry. High-resolution TEM and fast Fourier transform analysis confirm crystallographic coherence at the film–substrate interface. The electrical conductivity exhibits a metal–insulator transition at TMIT ≈ 423 K with no measurable thermal hysteresis and a total change of ~1.6 orders of magnitude between 300 and 480 K. These results establish crystallographic registry in epitaxial V3O5 thin films and provide a structurally well-defined system for future studies of orientation-dependent transport.\r\nT

36 MATERIALS SCIENCE↗

DOE OSTI2023

Intrinsic thermal expansion and tunability of thermal expansion coefficient in Ni-substituted Co 2 V 2 O 7

Abstract Framework oxide materials are well-known for exhibiting not only negative thermal expansion (NTE), but also demonstrating thermal expansion that can be controlled using composition as a tuning parameter. In this work, we study the intrinsic thermal expansion properties of Co 2 V 2 O 7 , which has shown bulk linear NTE, and attempt to understand how substituting Ni 2+ for Co 2+ will affect the thermal expansion. The isomorphic solid solution is synthesized through solid-state methods and characterized using x-ray diffraction (XRD), diffuse reflectance spectroscopy, and neutron diffraction. The size difference between Ni 2+ and Co 2+ as well as the polyhedral volume of each Co 2+ metal coordination environment in the crystal structure allows Ni 2+ to partially be directed toward one crystallographic site over the other. Variable temperature synchrotron XRD data are employed to understand intrinsic thermal expansion. Across the solid solution, no intrinsic NTE is observed at the microscopic level, yet a degree of tunability in the thermal expansion coefficient with Ni substitution is demonstrated. The disparities between the intrinsic and bulk thermal expansion properties suggest that a morphological mechanism may have resulted in NTE in the bulk.

Materials Science↗

DOE OSTI2020

Impact of Alloy-Disorder-Induced Localization on Hole Diffusion in Highly Excited c -Plane and m -Plane (In, Ga) N Quantum Wells

The diffusion coefficient of holes can provide knowledge about carrier localization in (In, Ga)N, where the carrier dynamics are altered by randomly fluctuating potential landscape. In group-III nitrides, the diffusivity of holes is difficult to measure by electrical methods but it can be studied using optical techniques. Here, we investigate the dependence of the hole diffusion coefficient on direction and carrier density in c-plane and m-plane (In, Ga)N structures by employing the light-induced transient-grating technique. We show that the hole diffusion coefficient is anisotropic in the m-plane structure, where it is several times larger along the a crystallographic direction than along the c direction. Such anisotropy is observed within the broad range of carrier densities from 10 18 to 10 20 cm –3 . The diffusivity changes nonmonotonously with increasing photoexcitation, this dependence being different in thick and thin layers. We argue that an unexpectedly high diffusion coefficient at low carrier densities in thick quantum wells can be a signature of efficient hole transport via percolative paths occurring due to compositional disorder. In turn, a decrease of diffusivity with the excitation can reflect the effect of Coulomb blockade of these paths. Lastly, we demonstrate that disorder impacts carrier diffusivity even at carrier densities above 10 19 cm –3 , where the overflow of localized states must be included to explain the observed increase of the diffusion coefficient with the carrier density.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Electrolyte Solvation and Ionic Association: Part IX. Structures and Raman Spectroscopic Characterization of LiFSI Solvates

The bis(fluorosulfonyl)imide anion N(SO 2 F) 2 ⁻ (i.e., FSI⁻) (also referred to as bis(fluorosulfonyl)amide (i.e., FSA-) and imidodi(sulphuryl fluoride)) has attracted tremendous interest in recent years for its utility in both lithium salts and ionic liquids for battery electrolyte applications. To facilitate the understanding of the characteristics of this anion, crystal structures are reported here for the uncoordinated anion in LiFSI-based solvates with cryptand CRYPT-222 and tetraglyme (G4). These crystalline solvates were analyzed by Raman spectroscopy to aid in assigning the Raman bands to the modes of ion coordination found in liquid electrolytes. These structures, as well as a thorough review of other relevant crystallographic data, provide insights into the rather remarkable properties of the FSI- anion with regard to solvate formation and electrolyte properties.

25 ENERGY STORAGE↗

DOE OSTI2023

Gas-mediated trace element incorporation into rhyolite-hosted topaz: A synchrotron microbeam XAS study

Magmatic gas exsolving during late-stage cooling of shallow magmas has been considered an important facilitator of low-pressure alteration and metal transport. However, the chemical properties of such gas, particularly its metal transport mechanisms and capacity, remain elusive. Trace elements in minerals produced by gas-mediated surface reaction or precipitation from gas capture details of gas composition and reaction pathways. However, interpretation of mineral trace element contents is dependent on understanding crystallographic controls on gas/mineral partitioning. Here, this work investigates the structural accommodation of As, Mn, Ga, Ge, Fe, and Ti in vapor-deposited topaz of vesicular topaz rhyolite from the Thomas Range, Utah, through single-crystal synchrotron microbeam X-ray techniques on picogram quantities of those trace elements. X-ray absorption near edge structure (XANES) data indicates that these elements are incorporated into topaz as As 5+ , Fe 3+ , Mn 3+ , Ti 4+ , Ga 3+ , and Ge 4+ . Extended X-ray absorption fine structure (EXAFS) analysis for these trace elements, compared to EXAFS of structural Al and Si, reveals that As 5+ and Ge 4+ are incorporated directly into the tetrahedral site of the topaz structure, with the octahedral site accommodating Mn 3+ , Fe 3+ , Ga 3+ , and Ti 4+ . For As 5+ and Fe 3+ , the structural impact of substitution extends to at least second neighbors (other elements were only resolvable to first neighbors). Further interpretation of the EXAFS results suggests that the substitution of Ti 4+ results in increased distortion of the octahedral site, while the other trace elements induce more uniform expansion correlating in magnitude to their ionic radius. Comparison of quantified X-ray fluorescence (XRF) data for two topaz crystals from this rhyolite reveals variable trace element concentrations for As 5+ , Fe 3+ , Ga 3+ , and Ti 4+ , reflective of a source gas undersaturated in these trace elements changing in concentration over the period of topaz deposition. The identical Ge 4+ content of the two topaz crystals suggests that Ge 4+ in the gas was buffered by the growth of another Ge 4+ -bearing phase, such as quartz. The very low Mn 3+ content in the topaz crystals does not reflect the abundance of Mn 3+ in the gas (saturation of Mn is evidenced by coexisting bixbyite). Instead, it suggests a strong Jahn-Teller inhibitory effect to the substitution of Mn 3+ for Al 3+ in the distorted octahedral site of topaz. It is proposed that exsolution of an HF-enriched gas from cooling rhyolitic magma led to local scouring of Al, Si, and trace metals from the magma. Once topaz crystals nucleated, self-catalyzed reactions that recycle HF led to continued growth of topaz.

36 MATERIALS SCIENCE↗

DOE OSTI2023

The synthesis of novel lanthanum hydroxyborate at extreme conditions

The novel structure of lanthanum hydroxyborate La 2 B 2 O 5 (OH) 2 was synthesized by the reaction of partially hydrolyzed lanthanum and boron oxide in a diamond anvil cell under high-pressure/high-temperature (HPHT) conditions of 30 GPa and ~2,400 K. The single-crystal X-ray structure determination of the lanthanum hydroxyborate revealed: P$\overline{3}$c1 , a = 6.555(2) Å, c = 17.485(8) Å, Z = 6, R 1 = 0.056. The three-dimensional structure consists of discrete planar BO 3 groups and three crystallographically different La ions: one is surrounded by 9, one by 10, and one by 12 oxygen anions. The band gap was estimated using ab initio calculations to be 4.64 eV at ambient pressure and 5.26 eV at 30 GPa. The current work describes the novel HPHT lanthanum hydroxyborate with potential application as a deep-ultraviolet birefringent material.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Isolation, Structural Analysis and Biological Activity Assays of Biselisabethoxanes A and B: Two Dissymmetric Bis-Diterpenes from the Southwestern Caribbean Sea Gorgonian Coral Pseudopterogorgia elisabethae

Two novel dissymmetric diterpenoids, biselisabethoxanes A and B (1 and 2), were isolated from the hexane extracts of the gorgonian coral Pseudopterogorgia elisabethae. Biselisabethoxane A (1) represents the first example of a marine-derived C40 dimer made of two distinct diterpene fragments, whereas biselisabethoxane B (2) is a fused heterodimer stemming from coupling of two amphilectane-based fragments. The structures of 1 and 2 were elucidated based on 1D and 2D NMR spectral data analysis. The molecular structure of 1 was subsequently confirmed by X-ray crystallographic analysis. When evaluated for their inhibitory effects in a series of well-established biological activity assays the isolated compounds were shown to moderately inhibit the growth of Mycobacterium tuberculosis.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1977

Investigation of the fracture mechanism in Ti-5Al-2.5Sn at cryogenic temperatures

The influence of microstructure on the fracture mechanism and plane-strain fracture toughness of Ti-5Al-2.5Sn was studied through the use of fractography and metallographic sectioning techniques. One-inch thick plates of extra low interstitial (ELI) and normal interstitial Ti-5Al-2.5Sn were mill annealed at 815 C followed by either air or furnace cooling. These variations in composition and cooling rate resulted in differences in the volume fraction and internal structure of the iron-stabilized phase, and in the crystallographic texture and ordering of the alpha matrix. The tensile properties of these plates were determined at 20 K, 77 K, and 295 K. The air-cooled ELI plate was the toughest material evaluated.

Vanstone, R. H.↗

NASA NTRS2007

Development and Processing Improvement of Aerospace Aluminum Alloys

This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

Lisagor, W. Barry↗