The effect of adding Mn and Cr to the Al-Fe-Si system alloy

Phase composition and valence of pulsed laser deposited vanadium oxide thin films at different oxygen pressures

The phase composition of Li1?xHxNbO3 and Li1?xHxTaO3 waveguide layers produced ?t different modifications of the proton exchange (PE) technology and having complex phase composition with different quota of the phases present is analyzed based on their mode and IR spectra. The intrinsic stress caused by crystal lattice deformations at a relatively high level of hydrogen doping in the PE layers is estimated by the optical integral method. An attempt to explain the level of stress is made based on the phase composition of the studied samples. The results contribute to a better understanding of the properties and characteristics of such waveguides.

Electron-beam additive manufacturing is one of the most promising methods for creating complex metal parts and structures. Additive manufacturing has already gained wide acceptance in the creation of various constructions from aluminum, copper, titanium, and their alloys as well as different classes of steels and other metallic materials. However, there are still many challenges associated with the additive manufacturing and post-production processing of intermetallic alloys. Thus, it is currently an urgent task for research. In this work, heat-resistant intermetallic alloys based on nickel, aluminum, and chromium were produced by dual-wire electron-beam additive manufacturing using commercial NiCr and Al wires. The microstructure, phase composition, and microhardness of the intermetallic billets are strongly dependent on the ratio of NiCr and Al wires, which have been fed during the additive growth of the material (NiCr:Al = 3:1 and NiCr:Al = 1:3). A metal-matrix composite material (Al3Ni-based intermetallide in Al-based matrix) was fabricated using the NiCr:Al = 1:3 ratio of the wires during the deposition. In tension, it fractures in a brittle manner before the plastic deformation starts, and it possesses a high microhardness of 6–10 GPa with a high dispersion of the value (the mean value is 8.7 GPa). This is associated with the complex phase composition of the material and the high fraction of a brittle Al3Ni intermetallic phase. In the material, obtained with the ratio NiCr:Al = 3:1, the ordered Ni3Al(Cr) and disordered Ni3Cr(Al) intermetallides are the dominating phases. Its microhardness turned out to be lower (4.1 GPa) than that in Al + Al3Ni-based composite, but intermetallic Ni3Al-based alloy demonstrates good mechanical properties in a high-temperature deformation regime (650 MPa, more than 10% elongation at 873 K). Microstructural studies, analysis of phase composition, and tensile mechanical properties of additively produced intermetallic materials show the perspective of dual-wire electron-beam additive manufacturing for producing intermetallic compounds for high-temperature applications.

Structural and phase transformations that occur in Fe(Fe3C, Fe3SiC)-SiO2 (amorphous quartz) systems during mechanical alloying in an Ar atmosphere and in air have been studied by X-ray diffraction, Mossbauer spectroscopy, IR spectroscopy, electron microscopy, and magnetometry. It has been shown that the mechanoactivation treatment leads to the formation of isolated particles 2–20 nm in size with a complex phase composition (Fe, FeSi alloy, oxides, silicates, and carbides), which depends on the milling atmosphere. It has been found out that the magnetic properties of such systems strongly depend on the oxygen and carbon compounds existing in the system, which cannot be detected by X-ray diffraction, but their presence is testified by the data of Mossbauer spectroscopy.

1. In all the investigated steels saturation with boron leads to the formation of a heterophase structure characterized by dispersity of the structural components, chemical and structural inhomogeneity. In a thin surface layer of the treated zone metallography reveals molten boron particles which did not have time to react with the liquid metal. 2. In dependence on the marque of steel the boronized layers have different phase composition, and in addition to α- and γ-solid solutions they contain iron boride Fe2B and also complex boron carbides with different stoichiometric composition. Metastable crystalline phases were not discovered in the investigated specimens. 3. Laser boronizing increases microhardness because of the more complex phase composition as well as other changes of the structure connected with the high cooling rates of the alloyed layers.

refractory WC particles. Alloys of titanium grades VT3-1 and VT-20 were used as substrate material. Alloy VT3-1 is two-phase (a +/3), and alloy VT-20 is single-phase (/3). The thickness of coatings is 100-400 pro, and the technology for preparing them is described in [1, 2]. The temperature--time regime for applying detonation coatings was established by a modelling method using laser stroboscope data. Information about the mass transfer process was obtained by electron probe analysis, and about phase transformations by the x-ray analysis method. The composition of different regions of coatings was determined (Tables 1 and 2). Quite complete information about the nature of the distribution of elements in the diffusion reaction zone for coatings is given by pictures (Fig. 1) obtained in characteristic x-radiation of the corresponding elements in units of the MS-46 Cameca and Superprobe-733 types, and also curves for the distribution of elements along electron probe scanning lines in a direction perpendicular to the boundary of the coating with the substrate (Fig. 2). Data for the phase composition of coatings prepared on the basis of analyzing Debye diffraction pictures recorded in a DRON-2.0 unit of Cu K,~-radiation (2 = 0.154 nm) in the form of line-diagrams are presented in Fig. 3). Given for comparison are line-diagrams for powder grade 72FNS in the original condition and also for a zone of coating separation from substrate VT3-1. X-ray analysis was also performed on coatings of powders of alloy VK-12 and a mechanical mixture of WC--Co powders applied to substrates of alloys VT3-1 and VT-20. Line-diagrams for the system WC--12% Co reflect typical pictures for the change in phase composition of the coating and substrate in different regions (at a different depth from the boundary) and they give information about the interconnection between diffusion processes (mass transfer) and phase transformations. X-ray analysis showed that a complex phase composition is typical for all regions of the coating. A change in it at the boundary with the substrate (in relation to the composition of the coating itself) points to occurrence of mass transfer both between WC--Co coating components, and also between the coating and substrate. Close to the boundary with the VT3-1

Lithium-rich layered oxides are promising cathode candidates for Li-ion batteries due to their high specific capacity than the commercial cathode material, LiCoO2. However, the mechanism of the incredibly high capacity and inherent problems of lithium-rich layered oxides, such as low initial Columbic efficiency and poor capacity retention, has not been explored in detail. Herein, lithium-rich layered oxide, Li1.2 Mn0.54Ni0.13Co0.13O2, has been synthesized by sol-gel method, which could be charged to 5 V (versus Li/Li+) and delivered a specific capacity of 248 mAh g−1. Then, a combination of XRD Rietveld refinement and HRTEM analysis has been employed to investigate the microstructure and phase composition of as-prepared Li1.2 Mn0.54Ni0.13Co0.13O2. The results revealed that Li1.2 Mn0.54Ni0.13Co0.13O2 nanoparticles consist of different phases, including LiCoO2 with R-3m symmetry, LiNiO2 with R-3m symmetry, LiMnO2 with R-3m symmetry, Li2MnO3 with c2/m symmetry, and Li2MnO3 with cmc/21 symmetry. It has been demonstrated that O2-Li2MnO3 phase with cmc/21 symmetry is responsible for the high reversible capacity of Li1.2 Mn0.54Ni0.13Co0.13O2 compound. However, the complex phase composition caused abundant stacking faults in the nanoparticles, which led to poor rate performance. The present study provides useful insights into the charge storage mechanism of a promising Li-ion battery cathode, Li1.2 Mn0.54Ni0.13Co0.13O2, which can be used for the development of novel electrode materials for next-generation LIBs due to its lower consumption of element Co and good electrochemical performance.

This paper deals with the crystallization of glass 30Li2O?15Nb2O5?50SiO2?5TiO2 (mol%). The crystallization behavior was studied under isothermal and non-isothermal conditions. XRD and SEM methods were employed for determination of phase composition and microstructure of crystallized glass. It was detected that this glass crystallizes by the surface crystallization mechanism. SEM micrographs of the crystallized samples revealed that the crystals grow in the form of dendrites. The glass-ceramics with complex phase composition was obtained. Three crystalline phases were detected where LiNbO3 has grown as primary phase and a secondary ones Li2Si2O5 and SiO2 appeared. The calculated average crystallite sizes are: 27 nm for LiNbO3 , 115 nm for Li2Si2O5 and 45 nm for SiO2 . From the experimental data an activation energy of crystals growth, calculated using the Kissinger relation, is Ea = 275 ?10 KJ / mol.

A comprehensive study of the structure and phase composition of a promising brand of electrically conductive carbon black was carried out. It is shown that the material under study has a complex phase composition, which, along with carbon, includes other elements and compounds, such as sulphur, oxygen, nitrogen, and vanadium oxides. The structural state of carbon black can be defined as amorphous. The presence of functional oxygen-containing groups in the material, presumably attached to the edge carbon atoms of graphene layers, has been proved. The interrelation of some characteristics of the structure and phase composition of the material and the properties of polymer composites is discussed.

Thermodesorption processes of mono-and multilayers of fatty acids and their salts with 14 to 24 carbon atoms were investigated by ellipsometry and IR spectroscopy. Cadmium, calcium, strontium, and barium salt layers, unlike the layers of pure acids, have a complex phase composition which includes not only separate acid and salt phases, but also intermediate acid-salt forms. The initial phase composition of multilayer systems determines their thermodesorption spectrum observed upon heating the samples. It was found that before the removal of molecules to the gaseous phase, phase transitions are possible in the films, similar to those observed in crystals and caused by the change of molecular conformations in the layer. Energy characteristics of thermodesorption processes are estimated for pure acid layers and for separate phases in salt layers. Possible qualitative models of the processes are discussed.

Structure and electrochemical properties of cobalt-free perovskite cathode materials for intermediate-temperature solid oxide fuel cells

The present work describes the effect of long-term (8 weeks) high-temperature oxidation (500 °C) on the formation of an oxide layer as well as on the microstructure and mechanical properties of the 3D-printed 18Ni-300 maraging steel. For this purpose, samples produced by additive manufacturing in the as-built and the as-built + solution annealed and aging treated states were used. The as-built + solution annealed and aging treated material was found to be more prone to oxide layer formation due to a homogeneously distributed Ni3Mo intermetallic phase in the material matrix compared to the as-built material. The 8 weeks long exposure to a temperature of 500 °C has caused the formation of a thick oxide layer that exhibited a very bad adhesion with the metal matrix/oxide. The X-ray diffraction analysis confirmed the formation of a layer with a complex phase composition: martensite, austenite, Fe2O3, and Fe3O4. Moreover, the presence of CoFe2O4 was determined on the thin outer oxide layer using X-ray photoelectron spectroscopy. The phenomenon of over-aging was found to be the most significant after the first week of high-temperature oxidation. Then, a negligible change in the microhardness was observed throughout the entire experiment. X-ray diffraction analysis and energy dispersive spectroscopy confirmed the phase composition of the alloy corresponding to 75% of martensite + 25% of austenite as well as the change of Ni3Mo precipitate to Ni3(Mo, Ti) type after the long-term oxidation.

Chapter 88 Phase equilibria and crystal chemistry in ternary rare earth systems with metallic elements

Hydration kinetics analysis of cementitious paste composites produced by binary and ternary binder materials for potential use in massive concrete structures

Investigation of the γ-Ti(Cr,Al)2 phase at 800 °C and 1000 °C