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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Interplay of hidden orbital order and superconductivity in CeCoIn5

Abstract Visualizing atomic-orbital degrees of freedom is a frontier challenge in scanned microscopy. Some types of orbital order are virtually imperceptible to normal scattering techniques because they do not reduce the overall crystal lattice symmetry. A good example is d xz / d yz (π,π) orbital order in tetragonal lattices. For enhanced detectability, here we consider the quasiparticle scattering interference (QPI) signature of such (π,π) orbital order in both normal and superconducting phases. The theory reveals that sublattice-specific QPI signatures generated by the orbital order should emerge strongly in the superconducting phase. Sublattice-resolved QPI visualization in superconducting CeCoIn 5 then reveals two orthogonal QPI patterns at lattice-substitutional impurity atoms. We analyze the energy dependence of these two orthogonal QPI patterns and find the intensity peaked near E = 0, as predicted when such (π,π) orbital order is intertwined with d -wave superconductivity. Sublattice-resolved superconductive QPI techniques thus represent a new approach for study of hidden orbital order.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Synthesis and Characterisation of Caesium Phosphomolybdate and Zirconium Molybdate found in the Highly Active Storage Tanks at Sellafield - 18154

Caesium phosphomolybdate (Cs{sub 3}PMo{sub 12}O{sub 40}.xH{sub 2}O, CPM) and zirconium molybdate (ZrMo{sub 2}O{sub 7}(OH){sub 2}.xH{sub 2}O, ZM) are two known fission products that precipitate out within the Highly Active Storage Tanks (HASTs) at Sellafield, potentially causing 'hot-spots' and blocking pipes. Currently, there is not enough behavioural understanding of these compounds present in the Highly Active Liquor (HAL) for effective Post Operational Clean Out (POCO) strategic planning. As the HASTs do not have an in situ monitoring system the behaviour of the HAL cannot be directly observed. Therefore, as with this research, non-radioactive simulants can be utilised to aid behavioural understanding to assist with the planning of future waste management programs. CPM, along with two different morphologies of ZM were characterised and compared to the common oxide particle material titanium dioxide (TiO{sub 2}). The study provides a detailed physical characterisation of the simulants including: particle shape, particle size, water content and crystal structure, along with zeta particle potential, suspension settling and compressive yield stress. CPM was found to be spheroidal in nature with a particle size of 275 nm and an x value of 13 H{sub 2}O which crystallises as a cubic lattice with space group Pn-3m. ZM was found to have a range of morphologies from cuboidal to wheat-sheaf, varying in size from 10 μm to 20 μm, with an x value of between 3 and 4 H{sub 2}O, which crystallise as a body-centred tetragonal lattice with space group I4{sub 1cd}. TiO{sub 2} used as a comparison simulant was found to be spheroidal in shape with particle size of 725 nm. The isoelectric points (IEPs) of the two ZM samples (ZM-A and ZM-B) with different morphologies were found to be pH 2.5, while for TiO{sub 2} it was pH 3.2. For CPM it could not be confidently identified due to its instability within the acidic environment. The settling rates and compressive yield stress of all simulants were tested in both water and 2 M nitric acid, conditions that replicate the HASTs. TiO{sub 2}, ZM-A and ZM-B all found settled faster in acid than in water. For CPM, slightly faster settling in acid was measured. For all samples it was found that as the particle concentration increased the settling rate decreased, which is a result of hindered settling. For compressive yield stress, similar trends were observed for CPM with little variation in its behaviour in acid and water, suggesting that the particles are highly aggregated in both fluids. For ZM samples little change in equilibrium volume fraction was measured with an increase in pressure (both acid and water). However, overall the sediment bed was denser in water, a result of the rapid settling in acid not allowing the non-spherical particles to pack in an ordered manner. It has been highlighted that both CPM and ZM within the acidic conditions of the HASTs, result in unstable and aggregated compounds, which settle quickly to form large open networks. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Spin-orbital order and excitons in magnetoresistive HoBi

The magnetism of the rocksalt fcc rare-earth monopnictide HoBi, a candidate topological material with extreme magnetoresistance, is investigated. From the Ho 3+ non-Kramers J=8 spin-orbital multiplet, the cubic crystal electric field yields six nearly degenerate low-energy levels. These constitute an anisotropic magnetic moment with a Jahn-Teller-like coupling to the lattice. In the cubic phase for T>T N =5.72(1)K, the paramagnetic neutron scattering is centered at k=($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) and was fit to dominant antiferromagnetic interactions between Ho spins separated by {100} and ferromagnetic interactions between spins displaced by {$\frac{1}{2}$ $\frac{1}{2}$ 0}. For T < T N , a type-II AFM long-range order with k=($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) develops along with a tetragonal lattice distortion. While neutron diffraction from a multidomain sample cannot unambiguously determine the spin orientation within a domain, the bulk magnetization, structural distortion, and our measurements of the magnetic excitations all show the easy axis coincides with the tetragonal axis. Finally, the weakly dispersive excitons for T < T N can be accounted for by a spin Hamiltonian that includes the crystal electric field and exchange interactions within the random phase approximation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Influence of chemical strains on the electrocaloric response, polarization morphology, tetragonality, and negative-capacitance effect of ferroelectric core-shell nanorods and nanowires

Using Landau-Ginzburg-Devonshire (LGD) approach, we proposed the analytical description of the influence of chemical strains on spontaneous polarization and the electrocaloric response in ferroelectric core-shell nanorods. We postulate that the nanorod core presents a defect-free single-crystalline ferroelectric material, and elastic defects are accumulated in the ultrathin shell, where they can induce tensile or compressive chemical strains. Finite-element modeling (FEM) based on the LGD approach reveals transitions of domain-structure morphology induced by chemical strains in the Ba Ti O 3 nanorods. Namely, tensile chemical strains induce and support the single-domain state in the central part of the nanorod, while the curled domain structures appear near the unscreened or partially screened ends of the rod. The vortexlike domains propagate toward the central part of the rod and fill it entirely, when the rod is covered by a shell with compressive chemical strains above some critical value. The critical value depends on the nanorod sizes, aspect ratio, and screening conditions at its ends. Both analytical theory and FEM predict that the tensile chemical strains in the shell increase the nanorod polarization, lattice tetragonality, and electrocaloric response well above the values corresponding to the bulk material. The physical reason for the increase is strong electrostriction coupling between the mismatch-type elastic strains induced in the core by chemical strains in the shell. Comparison with earlier XRD data confirmed an increase of the tetragonality ratio in tensile Ba Ti O 3 nanorods compared to the bulk material. Obtained analytical expressions, which are suitable for the description of strain-induced changes in a wide range of multiaxial ferroelectric core-shell nanorods and nanowires, can be useful for strain engineering of advanced ferroelectric nanomaterials for energy storage, harvesting, electrocaloric applications, and negative capacitance elements. Published by the American Physical Society 2024

36 MATERIALS SCIENCE↗
DOE OSTI2022

Role of electromagnetic gauge-field fluctuations in the selection between chiral and nematic superconductivity

Motivated by the observation of nematic superconductivity in several systems, we revisit the problem of the leading pairing instability of two-component unconventional superconductors on the triangular lattice—such as (p x , p y )-wave and (d x 2 –y 2 , d xy )-wave superconductors. Such a system has two possible superconducting states: the chiral state (e.g., p + ip or d + id), which breaks time-reversal symmetry, and the nematic state (e.g., p + p or d + d), which breaks the threefold rotational symmetry of the lattice. Weak-coupling calculations generally favor the chiral over the nematic superconducting state, raising the question of what mechanism can stabilize the latter. Here, we show that the electromagnetic field fluctuations can play a crucial role in selecting between these two states. Specifically, we derive and analyze the effective free energy for the two-component superconducting order parameter after integrating out the gauge-field fluctuations, which is formally justified if the spatial order parameter fluctuations can be neglected. A nonanalytic cubic term arises, as in the case of a conventional s -wave superconductor. However, unlike the latter, the cubic term depends on the relative phase and on the relative amplitudes between the two order parameter components, in such a way that it generally favors the nematic state. This result is a direct consequence of the fact that the stiffness of the superconducting order parameter is not isotropic. Competition with the quartic term, which favors the chiral state, leads to a renormalized phase diagram in which the nematic state displaces the chiral state over a wide region in the parameter space. Here, we analyze the stability of the fluctuation-induced nematic phase, generalize our results to tetragonal lattices, and discuss their applicability to candidate nematic superconductors, including twisted bilayer graphene.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Designing Magnetic Anisotropy through Strain Doping

Abstract The coupling between a material's lattice and its underlying spin state links structural deformation to magnetic properties; however, traditional strain engineering does not allow the continuous, post‐synthesis control of lattice symmetry needed to fully utilize this fundamental coupling in device design. Uniaxial lattice expansion induced by post‐synthesis low energy helium ion implantation is shown to provide a means of bypassing these limitations. Magnetocrystalline energy calculations can be used a priori to estimate the predictive design of a material's preferred magnetic spin orientation. The efficacy of this approach is experimentally confirmed in a spinel CoFe 2 O 4 model system where the epitaxial film's magnetic easy axis is continuously manipulated between the out‐of‐plane (oop) and in‐plane (ip) directions as lattice tetragonality moves from ip to oop with increasing strain doping. Macroscopically gradual and microscopically abrupt changes to preferential spin orientation are demonstrated by combining ion irradiation with simple beam masking and lithographic procedures. The ability to design magnetic spin orientations across multiple length scales in a single crystal wafer using only crystal symmetry considerations provides a clear path toward the rational design of spin transfer, magnetoelectric, and skyrmion‐based applications where magnetocrystalline energy must be dictated across multiple length scales.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Distinct Composition‐Dependent Topological Hall Effect in Mn 2‐x Zn x Sb

Abstract Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect (THE), a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn 2‐x Zn x Sb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high‐Zn ( x > 0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low‐Zn ( x < 0.6) samples show an opposite trend. The coexistence of those distinct temperature dependencies for THE suggests very different magnetic interactions/structures for different compositions and underscores the strong coupling between magnetism and transport in Mn 2‐x Zn x Sb. The findings contribute to understanding topological magnetism in centrosymmetric tetragonal lattices, establishing Mn 2‐x Zn x Sb as a unique platform for exploring tunable transport effects and opening avenues for further exploration in the realm of spintronics.

Nabi, Md Rafique Un↗
DOE OSTI2024

Enhancing Mechanical Properties of Carbon–Silicon Steel through Two–Stage Quenching and Partitioning with Bainitic Transformation: Ultimate Tensile Strength of 1875 MPa and Total Elongation of 8.03%

To achieve the desired microstructural properties, the ongoing development and innovation in new structural steels require novel thermal processing. This study aims to improve the mechanical properties of a commercial spring carbon–silicon steel by tailoring its microstructure through a process involving quenching and partitioning (Q&P) followed by bainitic transformation. A two–stage Q&P process is proposed to generate a nanoscale dispersion of stable retained austenite and carbides within the tempered martensite and bainite microstructure. The resulting tensile properties demonstrate a yield strength of 1280 MPa, an ultimate tensile strength of 1875 MPa, and a total elongation of 8.03%. These values surpass those of conventional spring 9254 steel, highlighting the effectiveness of the thermal treatment design. Microstructure analysis reveals the presence of tempered martensite, bainite sheaves, nanoscale carbides, and aggregates of retained austenite. Moreover, the resulting body–centered cubic matrix exhibits minimal lattice tetragonality of ≈1.0051, coupled with stable retained austenite featuring a carbon concentration of ≈3.42 ± 0.5 wt%, resulting in outstanding strength–ductility properties. In conclusion, these findings indicate that the proposed two–stage Q&P process, followed by bainitic transformation, significantly enhances the mechanical properties of carbon–silicon steels, making it a promising candidate for high–performance spring applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Behavior of yttria-stabilized zirconia (YSZ) during laser direct energy deposition of an Inconel 625-YSZ cermet

Thermal barrier coatings (TBC) are regularly used today to protect and extend the service life of several superalloys which are extensively used in high temperature applications. The existing TBCs are typically between 0.1 to 0.5 mm in thickness, are deposited on metal substrates using plasma spray or electron beam vapor deposition, and can reduce temperatures at the substrate surface by up to 300 °C. For greater temperature reductions there is a need for thicker TBCs. The building of thick TBCs has to date been stymied by poor adhesion, and cracking during deposition. It has been suggested that a functionally graded approach may reduce the residual stresses which result in these defects. To date there have been few reports on the deposition of ceramic or cermet coatings using laser AM and none have reported on the phase stability of ceramic particles post-deposition. This article is a first report on the phase stability of ceramic particles following the compositional segregation of elements during deposition using a powder feed additive manufacturing process. Functionally graded (FG), thick TBCs (>3 mm) consisting of Inconel 625 (IN625) and yttria-partially stabilized zirconia (8YSZ) were deposited on an A516 steel substrate via laser direct energy deposition (LDED). Good interfaces were observed between the bond coat (BC) and first cermet layer and between the graded cermet layers. However, cermet layers deposited with 10 wt.% or more YSZ developed a thin layer of YSZ on the surface. The thin layer of YSZ greatly hindered additional deposition of new cermet layers. In cermet layers that did exhibit good interfaces, fine, re-solidified, YSZ particles were homogenously distributed within the Inconel 625 matrix. The YSZ particles exhibited a tetragonal lattice structure and were depleted of yttrium. In contrast, the thin YSZ layer formed on a cermet surface showed no yttrium depletion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Spin fluctuations in the 112-type iron-based superconductor Ca 0.82 La 0.18 Fe 0.96 Ni 0.04 As 2

Abstract We report time-of-flight inelastic neutron scattering (INS) investigations on the spin fluctuation spectrum in the 112-type iron-based superconductor (FeSC) Ca 0.82 La 0.18 Fe 0.96 Ni 0.04 As 2 (CaLa-112). In comparison to the 122-type FeSCs with a centrosymmetric tetragonal lattice structure (space group I 4 / m m m ) at room temperature and an in-plane stripe-type antiferromagnetic (AF) order at low temperature, the 112 system has a noncentrosymmetric structure (space group P 2 1 ) with additional zigzag arsenic chains between Ca/La layers and a magnetic ground state with similar wavevector Q A F but different orientations of ordered moments in the parent compounds. Our INS study clearly reveals that the in-plane dispersions and the bandwidth of spin excitations in the superconducting CaLa-112 closely resemble to those in 122 systems. While the total fluctuating moments ⟨ m 2 ⟩ ≈ 4.6 ± 0.2 μ B 2 /Fe are larger than 122 system, the dynamic correlation lengths are similar ( ξ ≈ 10 Å). These results suggest that superconductivity in iron arsenides may have a common magnetic origin under similar magnetic exchange couplings with a dual nature from local moments and itinerant electrons, despite their different magnetic patterns and lattice symmetries.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Existence of a flat band in highly correlated metal BaCo 2 P 2

We report on the observation of a flat band situated at the Fermi level E F along with the structural, electrical transport, and magnetic properties of BaCo 2 P 2 that crystallizes in the ThCr 2 Si 2 -type body-center tetragonal structure. This compound has the largest inter-layer pnictide (Pn) distance d Pn–Pn as well as the largest c/a ratio among all the known ACo 2 Pn 2 (A = alkaline earth metal) compounds, where a and c are the tetragonal lattice parameters. Hence, the magnetic and electronic properties of this compound are expected to have a quasi-two-dimensional character. Despite the evidence of the presence of sizable magnetic interactions, magnetic susceptibility χ(T) of BaCo 2 P 2 does not show magnetic ordering down to 1.8 K. The material shows good metallic conduction with a large residual resistivity ratio ρ 300 K /ρ 1.8 K ≈ 70 and a Fermi liquid behavior at low temperature. Kadowaki–Woods ratio R KW of BaCo 2 P 2 suggests the presence of sizable electronic correlations within this system. Additionally, a large many-body enhancement of 2.3 of the experimental density of states D γ (E F ) over the band-structure D band (E F ) is inferred to arise from sizable electron-electron and/or electron-phonon interactions leading to a substantial deviation from the free-electron behavior.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Multi-task graph neural networks for simultaneous prediction of global and atomic properties in ferromagnetic systems *

Abstract We introduce a multi-tasking graph convolutional neural network, HydraGNN, to simultaneously predict both global and atomic physical properties and demonstrate with ferromagnetic materials. We train HydraGNN on an open-source ab initio density functional theory (DFT) dataset for iron-platinum with a fixed body centered tetragonal lattice structure and fixed volume to simultaneously predict the mixing enthalpy (a global feature of the system), the atomic charge transfer, and the atomic magnetic moment across configurations that span the entire compositional range. By taking advantage of underlying physical correlations between material properties, multi-task learning (MTL) with HydraGNN provides effective training even with modest amounts of data. Moreover, this is achieved with just one architecture instead of three, as required by single-task learning (STL). The first convolutional layers of the HydraGNN architecture are shared by all learning tasks and extract features common to all material properties. The following layers discriminate the features of the different properties, the results of which are fed to the separate heads of the final layer to produce predictions. Numerical results show that HydraGNN effectively captures the relation between the configurational entropy and the material properties over the entire compositional range. Overall, the accuracy of simultaneous MTL predictions is comparable to the accuracy of the STL predictions. In addition, the computational cost of training HydraGNN for MTL is much lower than the original DFT calculations and also lower than training separate STL models for each property.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Understanding the U 3 Si 2 crystal structure evolution as a function of temperature by neutron diffraction and simulation

U 3 Si 2 is actively researched as an accident tolerant fuel. Detailed knowledge of the crystal structure evolution, including knowledge of the anisotropic tetragonal lattice parameters, as a function of temperature and chemical composition is of paramount importance for predictions ranging from thermo-mechanical stresses to phase transformations to crystal lattice sites of fission products. Knowledge of the stability range of U 3 Si 2 is of great importance to understand whether changes of the stoichiometry, either from burn-up or due to synthesis variations, will lead to undesirable phase decomposition. To investigate these topics, stoichiometric U3Si2.00 and hyper-stoichiometric U 3 Si 2.01 were synthesized and characterized at ambient conditions and up to 1150°C using time-of-flight neutron diffraction on the HIPPO instrument at the Los Alamos Neutron Science Center (LANSCE) at LANL.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1977

Self-consistent structure of metallic hydrogen

A calculation is presented of the total energy of metallic hydrogen for a family of face-centered tetragonal lattices carried out within the self-consistent phonon approximation. The energy of proton motion is large and proper inclusion of proton dynamics alters the structural dependence of the total energy, causing isotropic lattices to become favored. For the dynamic lattice the structural dependence of terms of third and higher order in the electron-proton interaction is greatly reduced from static lattice equivalents.

Straus, D. M.↗
DOE OSTI2018

A New Ti{sub 9}O{sub 10} Nanophase Prepared by Heat-Treating Nonstoichiometric Milled TiO{sub y} Nanopowder

A Ti{sub 9}O{sub 10} nanophase (sp. gr. Immm) has been synthesized via high-energy milling followed by prolonged high-temperature vacuum heat treatment of nonstoichiometric TiO{sub y} titanium monoxide. The atomic structure and microstructure of Ti{sub 9}O{sub 10} have been investigated by X-ray powder diffraction and high-resolution transmission electron microscopy. According to quantum-chemical calculation results, macrocrystalline Ti{sub 9}O{sub 10} is less energetically favorable than a disordered cubic phase of the same composition, TiO{sub 10/9}, so the formation of the former phase is due to size effects.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Unusual effects of Be doping in the iron-based superconductor FeSe

Recent superconducting transition temperatures (T c ) over 100 K for monolayer FeSe on SrTiO 3 have renewed interest in the bulk parent compound. In KCl:AlCl 3 flux-transport-grown crystals of FeSe 0.94 Be 0.06 , FeSe 0.97 Be 0.03 and, for comparison, FeSe, this work reports doping of FeSe using Be—among the smallest of possible dopants, corresponding to an effective 'chemical pressure'. According to lattice parameter measurements, 6% Be doping shrank the tetragonal FeSe lattice equivalent to a physical pressure of 0.75 GPa. Using this flux-transport method of sample preparation, 6% of Be was the maximum amount of dopant achievable. At this maximal composition of FeSe 0.94 Be 0.06 , the lattice unit cell shrinks by 2.4%, T c —measured in the bulk via specific heat—increases by almost 10%, the T c versus pressure behavior shifts its peak T$onset\atop{c}$downwards by ~1 GPa, the high temperature structural transition around T S = 89 K increases by 1.9 K (in contrast to other dopants in FeSe which uniformly depress T S), and the low temperature specific heat γ increases by 10% compared to pure FeSe. Also, upon doping by 6% Be the residual resistivity ratio, ρ(300 K)/ρ(T → 0), increases by almost a factor of four, while ρ(300 K)/ρ(T=$+\atop{c}$) increases by 50%.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Salt-Induced Polymorphs Observed in Colloidal Single Crystals

Polymorphs are solid materials with the same chemical composition but different crystallographic structures. A unique aspect of polymorphs is that they exhibit different physical properties, such as solubility, melting point, density, color, hardness, and bioavailability. Here, we synthesized polymorphs of colloidal crystals engineered with DNA by slow-cooling gold nanoparticle-core programmable atom equivalents (PAEs, particles with DNA sequences that control their bonding characteristics) under salt concentrations ranging from 0.5 to 4 M NaCl. This approach yielded a diverse set of single-crystalline phases with cubic, tetragonal, and hexagonal lattice symmetries. The structural transitions observed here arise solely from the modulation of interparticle repulsion via ionic strength and thermal processing. Notably, in certain cases, we observed diffusionless phase transformations, wherein the superlattices evolve from cubic to lower-symmetry tetragonal lattices. By tuning the thermal stability and salt concentration, we captured intermediate, metastable body-centered tetragonal structures during the slow-cool process, indicating that subtle changes in free energy can direct crystallization to low-symmetry phases. In conclusion, this study demonstrates that thermal and ionic parameters can be tuned to access and stabilize colloidal crystal polymorphs with emergent structures and interesting functional properties.

Colloidal crystallization↗
DOE OSTI2019

An Investigation of the Wear Performance of Aged Inconel 718 Superalloy by the Fuzzy Logic Approach

In this study, the effects of δ, γ′ and γ″ phases on the microstructure and wear behavior of Inconel 718 alloy, produced by powder metallurgy technique, were analyzed experimentally and a fuzzy logic model was developed for the weight loss prediction after the wear tests. Aging process was carried out in two stages: firstly at 720 °C for 8 h and then at 620 °C for 6-10 h. Wear tests were performed at five different sliding distances (400-2000 m) for 1 ms{sup −1} sliding speed under 30 to 60 N loads. Weight loss prediction model was developed by using fuzzy logic method. SEM images of Inconel 718 alloy aged for 6, 8 and 10 h at 620 °C show intermetallic precipitates formed around particle boundaries. XRD examinations showed orthorhombic δ (Ni{sub 3}Nb), BCT γ″ (Ni{sub 3}Nb), FCC γ′ Ni{sub 3}(Al,Ti) hexagonal Laves (Fe{sub 2}Nb) phases formed in the structure with the same chemical composition and different crystal lattice. Accurate estimates were obtained in the developed fuzzy logic model. It was illustrated that this fuzzy logic model can be used successfully for the prediction of weight loss in wear tests of Inconel 718 alloy that was produced by powder metallurgy method.

36 MATERIALS SCIENCE↗