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Hydrogen plasma reduction of Zn and Pb bearing residues in an inductively coupled plasma process. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132689. [PMID: 37801976 DOI: 10.1016/j.jhazmat.2023.132689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/15/2023] [Accepted: 09/30/2023] [Indexed: 10/08/2023]
Abstract
The application of plasma fuming technology opens up new horizons for the treatment of zinc-bearing residues. The present work uses a lab-scale Inductively Coupled Plasma (ICP) setup to investigate the hydrogen plasma reduction of ZnO and PbO from the CaO-FeO-SiO2 based slags. Slag particles were melted when passing through the ICP torch, and the ZnO and PbO were reduced into Zn and Pb metal vapor by H2 molecules and H radicals in the thermal hydrogen plasma. The metal vapor condensed on the particle surface when the particles passed through the plasma torch tail due to the high cooling rate. The PbO and ZnO content increased toward the particle core, implying the PbO and ZnO reduction from the slag particle surface. The increase in H2 to Ar ratio or H2 flow rate, power input and S content of the slags accelerated the process.
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In-situ electrical conductivity monitoring of slag solidification during continuous cooling for slag recycling. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 161:234-244. [PMID: 36898247 DOI: 10.1016/j.wasman.2023.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/07/2023] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Large volumes of steel slag are produced annually, leading to significant environmental protection and sustainable development issues. An online technology to monitor the solidification process of steel slag can assist in obtaining the right mineralogy to valorize these slags or render them harmless. For this purpose, we investigated the electrical properties and microstructural relationships of a CaO-Al2O3-SiO2-MgO (CASM) slag during cooling using an innovative setup. The electrical impedance was determined over the frequency range of 20 Hz to 300 kHz at two cooling rates, and the solidification behaviour was observed simultaneously by confocal scanning laser microscopy (CSLM). Four zones can be distinguished in the conductivity-temperature curves for the slag cooled at 10 °C/min, whereas only two distinct zones are visible at 100 °C/min. The liquid fraction of the slag has a significant impact on the slag conductivity during cooling. The electrical conductivity is, therefore, an accurate indicator of the solidification degree. Different theoretical and empirical models were evaluated on their ability to relate the bulk conductivity of the slag to the liquid fraction. The empirical Archie's model proved to be the most suitable model for relating the bulk conductivity of the slag to the liquid fraction. In-situ electrical conductivity measurements during cooling can provide an online assessment of the slag solidification process, including indicating the appearance of solid precipitates, monitoring the growth of crystals, indicating complete solidification when no liquid phase remains, and indicating the cooling rate.
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Simulation of particle migration during viscosity measurement of solid-bearing slag using a spindle rotational type viscometer. Chem Eng Sci 2019. [DOI: 10.1016/j.ces.2019.06.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Quantitative Study on Dissolution Behavior of Nd 2O 3 in Fluoride Melts. Ind Eng Chem Res 2018; 57:1380-1388. [PMID: 30022805 PMCID: PMC6046218 DOI: 10.1021/acs.iecr.7b04125] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/11/2018] [Accepted: 01/12/2018] [Indexed: 11/28/2022]
Abstract
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The dissolution of rare earth oxides
in molten fluorides is a critical
step in the preparation of the corresponding rare earth metals by
oxide-fluoride electrolysis. However, quantitatively understanding
the nature of dissolution, especially in the case of molten salts,
is usually difficult to be achieved by postmortem characterization. In this paper, the dissolution behavior of Nd2O3 particles in molten fluorides was studied via in situ observation with confocal scanning laser microscopy.
Combining direct observation with thermodynamic analyses on the oxide
dissolution, the rate-limiting step(s) and the effects of parameters
like temperature, salt type, and composition on the dissolution rate
are identified. This study provides a methodology to estimate the
dissolution kinetics of rare earth oxides in molten fluorides during
their primary and secondary processing.
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Utilization of Stainless-steel Furnace Dust as an Admixture for Synthesis of Cement-based Electromagnetic Interference Shielding Composites. Sci Rep 2017; 7:15368. [PMID: 29133844 PMCID: PMC5684210 DOI: 10.1038/s41598-017-15779-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 11/01/2017] [Indexed: 11/09/2022] Open
Abstract
Electromagnetic interference (EMI) shielding receives attention due to the increasing abundance of electronics. The Cement based material can obtain EMI shielding properties through the use of appropriate “fillers” such as carbon, metal, and ferrite. As the most important by-product of stainless steelmaking operations, through the metal droplets and ferrite that it contains, stainless-steel dust can be considered as a potential filler for EMI shielding applications. We have therefore utilized stainless-steel dust as an admixture for the synthesis of cement-based EMI shielding composites and show that it raises the EMI shielding effectiveness. In particular, a 45 mass pct of stainless-steel dust mixture of 5 mm thickness results in the enhancement of EMI shielding effectiveness to 6–9 dB as tested in the frequency range of 500 MHz–1.5 GHz.
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Crystal structure of apatite type Ca2.49Nd7.51(SiO4)6O1.75. Acta Crystallogr E Crystallogr Commun 2016; 72:209-11. [PMID: 26958389 PMCID: PMC4770985 DOI: 10.1107/s205698901600089x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/15/2016] [Indexed: 11/18/2022]
Abstract
The title compound, Ca2+x Nd8-x (SiO4)6O2-0.5x (x = 0.49), was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space group P63/m and has the composition Ca2.49Nd7.51(SiO4)6O1.75 [dicalcium octa-neodymium hexa-kis-(ortho-silicate) dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO4)6O2 and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+x Nd8-x (SiO4)6O2-0.5x , where x = 0.49.
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Abstract
The reaction kinetics of Zn vapor with Fe3O4 (magnetite) were studied from 907 to 1100 °C using a new experimental setup that only allows contact between the reactants through a gas-solid reaction. Hematite was used to create the reaction pellets. Because of the reducing atmosphere in the setup, a magnetite layer is formed on the outside of the pellet, which in turn reacts with the Zn vapor. After reaction, Zn concentration profiles were measured in the reacted magnetite layer using field-emission gun electron probe microanalysis. The reaction was confirmed to be diffusion-controlled. The effect of both volume and grain-boundary diffusion was observed in each experiment. The temperature dependence of both the volume and grain-boundary diffusion coefficients was obtained along with the activation energies of the diffusion coefficients. This study provides crucial information for the development of technologies that are dependent on the reaction. One example is the in-process separation technology for the separation of Zn vapor from electric arc furnace off-gas.
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Formation of the ZnFe2O4 phase in an electric arc furnace off-gas treatment system. JOURNAL OF HAZARDOUS MATERIALS 2015; 287:180-187. [PMID: 25646901 DOI: 10.1016/j.jhazmat.2015.01.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/17/2015] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
To better understand the phenomena of ZnFe2O4 spinel formation in electric arc furnace dust, the dust was characterized with particle size analysis, X-ray fluorescence (XRF), electron backscatter diffraction (EBSD), and electron probe micro-analysis (EPMA). Different ZnFe2O4 formation reaction extents were observed for iron oxide particles with different particle sizes. ZnO particles were present as both individual particles and aggregated on the surface of larger particles. Also, the slag particles found in the off-gas were shown not to react with the zinc vapor. After confirming the presence of a ZnFe2O4 formation reaction, the thermodynamic feasibility of in-process separation - a new electric arc furnace dust treatment technology - was reevaluated. The large air intake and the presence of iron oxide particles in the off-gas were included into the thermodynamic calculations. The formation of the stable ZnFe2O4 spinel phase was shown to be thermodynamically favorable in current electric arc furnace off-gas ducts conditions even before reaching the post combustion chamber.
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Cementitious binders from activated stainless steel refining slag and the effect of alkali solutions. JOURNAL OF HAZARDOUS MATERIALS 2015; 286:211-219. [PMID: 25577317 DOI: 10.1016/j.jhazmat.2014.12.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 12/14/2014] [Accepted: 12/23/2014] [Indexed: 06/04/2023]
Abstract
With an aim of producing high value cementitious binder, stainless steel refining slag containing a high amount of CaO in γ-dicalcium silicate form was activated with NaOH and Na-silicate as well as KOH and K-silicate solutions, followed by steam curing at 80 °C. Higher levels of alkali-silicate in the activating solution resulted in higher cumulative heat suggesting accelerated reaction kinetics. With respect to compressive strength, higher levels of alkali silicate resulted in higher strength and the mortars with Na activator were found to have higher early strength than the ones with K activator. The long term strength was found to be similar, regardless of the alkali metal. Thermogravimetric, QXRD and FTIR analyses showed an increase in the amount of reaction products (C-S-H type) over time, further confirming the reactivity of the crystalline slag. Batch leaching results showed lower leaching of heavy metals and metalloids with K activator compared to the Na activator. These results demonstrate that the alkali type and the ratio of hydroxide to silicates have a significant impact on the hydration and mechanical strength development of the stainless steel slag. The above findings can aid in the recycling and valorization of these type of slags which otherwise end up landfilled.
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The influence of slag compositional changes on the chemical degradation of magnesia-chromite refractories exposed to PbO-based non-ferrous slag saturated in spinel. Ann Ital Chir 2015. [DOI: 10.1016/j.jeurceramsoc.2014.08.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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In Situ Observation on Lime Dissolution in Molten Metallurgical Slags – Kinetic Aspects. Ind Eng Chem Res 2014. [DOI: 10.1021/ie500070h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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From NdFeB magnets towards the rare-earth oxides: a recycling process consuming only oxalic acid. RSC Adv 2014. [DOI: 10.1039/c4ra13787f] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A recycling process was developed in which only oxalic acid is consumed to remove and separate the rare-earth metals from NdFeB magnets.
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Abstract
AbstractInterfacial microstructure of In/Pd ohmic contacts to n-GaAs was studied by various X-ray diffraction techniques and secondary ion mass spectroscopy (SIMS). Analysis of this interface after various annealing showed that In1-xGaxAs compounds are formed at the interface and the composition of these compounds depends upon the annealing temperature. As the temperature increases, the stoichiometry of the Inrich compounds tends toward higher concentrations of Ga. The low contact resistance is achieved by dividing the Schottky barrier between metal and GaAs into two barriers due to metal/Inl-xGaxAs and In1-xGaxAs/GaAs. The barrier due to In1-xGaxAs/GaAs is believed to be the main limiting factor in lowering of contact resistance. The observed ohmic behavior for sample annealed at 500°C for 20 s is attributed to the further reduction of this barrier.
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Strong magnetic field effects on solid-liquid and particle-particle interactions during the processing of a conducting liquid containing non-conducting particles. J Colloid Interface Sci 2012; 375:203-12. [PMID: 22443967 DOI: 10.1016/j.jcis.2012.02.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 11/28/2022]
Abstract
The behavior of micrometer-sized weak magnetic insulating particles migrating in a conductive liquid metal is of broad interest during strong magnetic field processing of materials. In the present paper, we develop a numerical method to investigate the solid-liquid and particle-particle interactions by using a computational fluid dynamics (CFDs) modeling. By applying a strong magnetic field, for example, 10 Tesla, the drag forces of a single spherical particle can be increased up to around 15% at a creeping flow limit. However, magnetic field effects are reduced when the Reynolds number becomes higher. For two identical particles migrating along their centerline in a conductive liquid, both the drag forces and the magnetic interaction will be influenced. Factors such as interparticle distance, Reynolds number and magnetic flux density are investigated. Shielding effects are found from the leading particle, which will subsequently induce a hydrodynamic interaction between two particles. Strong magnetic fields however do not appear to have a significant influence on the shielding effects. In addition, the magnetic interaction forces of magnetic dipole-dipole interaction and induced magneto-hydrodynamic interaction are considered. It can be found that the induced magneto-hydrodynamic interaction force highly depends on the flow field and magnetic flux density. Therefore, the interaction between insulating particles can be controlled by applying a strong magnetic field and modifying the flow field. The present research provides a better understanding of the magnetic field induced interaction during liquid metal processing, and a method of non-metallic particles manipulation for metal/ceramic based materials preparation may be proposed.
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Quantitative phase-field approach for simulating grain growth in anisotropic systems with arbitrary inclination and misorientation dependence. PHYSICAL REVIEW LETTERS 2008; 101:025502. [PMID: 18764194 DOI: 10.1103/physrevlett.101.025502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2008] [Indexed: 05/26/2023]
Abstract
A phase-field approach for quantitative simulations of grain growth in anisotropic systems is introduced, together with a new methodology to derive appropriate model parameters that reproduce given misorientation and inclination dependent grain boundary energy and mobility in the simulations. The proposed model formulation and parameter choice guarantee a constant diffuse interface width and consequently give high controllability of the accuracy in grain growth simulations.
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Three-dimensional phase field simulations of grain growth in materials containing finely dispersed second-phase particles. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pamm.200700007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bounding box algorithm for three-dimensional phase-field simulations of microstructural evolution in polycrystalline materials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:056702. [PMID: 18233785 DOI: 10.1103/physreve.76.056702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Indexed: 05/25/2023]
Abstract
Phase-field modeling has proven to be a versatile tool for simulating microstructural evolution phenomena, such as grain growth in polycrystalline materials. However, the computing time and computing memory requirements of a phase-field model pose severe limitations on the number of phase-field variables that can be taken into account in a practical implementation. In this paper, a sparse bounding box algorithm is proposed that allows the use of a large number of phase-field variables without excessive memory usage or computational requirements. The algorithm is applied to a three-dimensional model for grain growth in the presence of second-phase particles.
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Lattice Boltzmann method for double-diffusive natural convection. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:046705. [PMID: 17501014 DOI: 10.1103/physreve.75.046705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Indexed: 05/15/2023]
Abstract
A lattice Boltzmann method for double-diffusive natural convection is presented. The model combines a multicomponent lattice Boltzmann scheme with a finite-difference solution of the energy equation to simulate natural convection caused by gradients in temperature and concentration. The model is validated both in two and three dimensions, and the agreement with literature data is satisfactory. A case study of thermosolutal convection of air in a cubical enclosure with horizontal thermal and solutal gradients is presented, exhibiting a rich variety of flow structures.
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Space- and Time-Resolved Visualization of Acid Catalysis in ZSM-5 Crystals by Fluorescence Microscopy. Angew Chem Int Ed Engl 2007; 46:1706-9. [PMID: 17397082 DOI: 10.1002/anie.200604336] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Space- and Time-Resolved Visualization of Acid Catalysis in ZSM-5 Crystals by Fluorescence Microscopy. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200604336] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Lattice-Boltzmann modeling of dissolution phenomena. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:036316. [PMID: 16605660 DOI: 10.1103/physreve.73.036316] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Indexed: 05/08/2023]
Abstract
In this work, we present a lattice-Boltzmann model for the simulation of complex dissolution phenomena. We design boundary conditions to impose a fixed concentration or a surface flux for use in multicomponent lattice-Boltzmann models. These conditions can be applied to simulate complex reactive flow phenomena, e.g., in porous media. By combining the boundary conditions with a volume-of-fluid description of solid structures, the application area of the presented model is extended toward complex dissolution phenomena. The boundary conditions and the dissolution model are validated using benchmark problems with analytical solutions. The agreement is good in all tested cases.
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Lattice Boltzmann model for diffusion-controlled dissolution of solid structures in multicomponent liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:036308. [PMID: 16241572 DOI: 10.1103/physreve.72.036308] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Indexed: 05/05/2023]
Abstract
A lattice Boltzmann model for the dissolution of solid structures of arbitrary shape in multi-component liquids is developed. To model diffusion-controlled dissolution, a multicomponent boundary condition is presented to impose a fixed concentration on an arbitrarily located boundary. The dissolution rate of the solid is calculated based on the diffusion flow in the boundary layer. The model is validated using analytical solutions of simple dissolution problems in a static fluid, and is applied to the dissolution of a cylinder in a laminar flow.
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Abstract
Mechanically polished NiTi alloy (50 at% Ni) was subjected to heat treatment in air in the temperature range 300-800 degrees C and characterised by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. Thermogravimetry measurements were carried out to investigate the kinetics of oxidation. The results of thermodynamic calculations were compared to the experimental observations. It was found that NiTi alloy exhibits different oxidation behaviour at temperatures below and above 500 degrees C. A Ni-free zone was found in the oxide layer for oxidation temperatures of 500 degrees C and 600 degrees C. The oxidation at 500 degrees C produces a smooth protective nickel-free oxide layer with a relatively small amount of Ni species at the air/oxide interface, which is in favour of good biocompatibility of NiTi implants. The oxidation mechanism for the NiTi shape memory alloy is discussed.
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Layered growth of the quasicrystalline decagonal Al3Pd phase in Al/Pd lateral diffusion couples. PHYSICAL REVIEW LETTERS 1990; 64:2671-2674. [PMID: 10041780 DOI: 10.1103/physrevlett.64.2671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Solid-state amorphization in Al-Pt multilayers by low-temperature annealing. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:13067-13071. [PMID: 9948203 DOI: 10.1103/physrevb.39.13067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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