X-ray Diffraction Phase Research Articles

ON MICROSTRUCTURE AND CAVITATION EROSION BEHAVIOR OF MICROWAVE-SYNTHESIZED Ni-Al2O3-BASED COMPOSITE CLADDINGS

In this study, Ni-Al2O3-based composite clads on SS-316 substrates using a microwave irradiation method have been developed. Microwave-processed clads were characterized using various nondestructive techniques to investigate microstructure, phase analysis, porosity assessment and measurement of microhardness. The findings of the microstructural analysis demonstrated the formation of solid, metallurgically bonded and defect-free clads with a thickness of approximately 970[Formula: see text][Formula: see text]m. X-ray diffraction (XRD) phase analysis study confirmed the existence of hard and intermetallic phases in the clad region. Composite clad region exhibited a low porosity value of [Formula: see text]1.3%. The average microhardness of the clad region was 3.63 times that of the substrate region. Further, cavitation erosion (CE) behavior of the developed clads was investigated using vibration CE test rig under various stand-off distances and immersion depths. CE results showed that the composite clads exhibited 6.9 times better erosion resistance than SS-316 substrate. CE resistance increased with an increase in stand-off distance and the depth of immersion.

Phase diagram study and thermodynamic modeling of the MgO-Y2O3-MgF2-YF3 system

The phase diagram of the MgO-Y2O3-MgF2-YF3 system (Mg,Y//O,F reciprocal system) at 1273–1773 K was investigated for the very first time using a classical equilibrium/quenching and differential thermal analysis (DTA) experiments followed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) phase analyses. No ternary or quaternary crystalline phase was found, and the eutectic reactions in the reciprocal system were identified. The overall phase diagram of the reciprocal system was also calculated based on the thermodynamic modeling using the CALculation of PHAse Diagram (CALPHAD) method.

Local microstructural evolution and the role of residual stresses in the phase stability of a laser powder bed fused cold-work tool steel

Economic benefits for the tooling industry can be realized through laser powder bed fusion (LPBF) by the implementation of internal cooling channels or usage of near-net-shaping in additively manufactured tool steels. As the microstructural evolution of the latter has not been fully illuminated yet, this work intends to shed light on the influence of in-situ tempering processes on microstructure development and to clarify the influence of residual stresses on phase stability. Hence, a carbon-bearing cold-work tool steel was processed via LPBF without base plate preheating. Besides well-established techniques such as light optical and scanning electron microscopy, X-ray diffraction phase analysis showed significant differences depending on whether weld bead layers were in-situ tempered during LPBF or not. These tempered layers yielded higher austenite and lower carbide contents than the non-tempered top layers. To distinguish between different phases within the matrix, which is surrounded by a eutectic carbide network, correlative energy-dispersive X-ray spectroscopy, electron backscatter diffraction analysis and atom probe tomography (APT) were carried out. Neither the atomic resolution in APT delivered conclusive differences in chemical composition between martensite and austenite. Therefore, another austenite stabilization mechanism has to prevail for the investigated alloy, i.e., stress-related stabilization. This phenomenon was addressed by the evaluation of strain profile measurements in dependence of the part height. These experiments were performed by cross-sectional synchrotron micro-diffraction. Results showed that sample preparation has a great influence on the determined austenite amounts. Material removing processes, such as cutting, grinding, polishing, focused ion beam milling or ion slicing were made responsible for attenuating respectively extinguishing austenite phase stability.

Influence of HiPIMS pulse widths on the deposition behaviour and properties of CuAgZr compositionally graded films

In this work, the influence of different pulse widths (25, 50 and 100 μs) during high power impulse magnetron sputtering (HiPIMS) of copper, silver and zirconium was investigated in terms of plasma properties and properties of combinatorial composition gradient CuAgZr film libraries. In situ plasma diagnostics via optical emission spectroscopy (OES), time-of-flight mass spectrometry (TOFMS), and modified quartz crystal microbalance (m-QCM), followed by film ex situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations allowed to determine the effect of deposition parameters on the thin films' microstructural changes. Changing the pulse width, while keeping the duty cycle constant, modified the discharge composition in the target region and the ionised fraction of the sputtered species in the substrate region. The maximum Cu ionised fraction (19 %) was found for 50 μs, resulting in compact and smooth morphology for Cu-rich films, whereas short 25 μs pulses provided porous columnar films with rough surfaces, as the result from Ar+ bombardment. For Ag-rich films, Ag segregation allowed the deposition of dense layers, regardless of the used pulse width.Furthermore, low Ag (<10 at.%) CuAgZr films produced via HiPIMS and direct-current magnetron sputtering (DCMS) were compared in terms of structural and mechanical property changes as a function of Zr contents. For the studied chemical composition range, a linear relationship between Zr content, XRD phase shift and mechanical properties was observed for HiPIMS films, in contrast to DCMS's more abrupt transitions. An increase in hardness and elastic modulus (up to 44 % and 22 %, respectively) was found for the HiPIMS films compared to DCMS ones. The obtained results highlight HiPIMS's flexibility in providing a wide range of tailoring possibilities to meet specific application requirements, such as crystalline microstructure, density and associated mechanical properties.

Features of microstructure, phase composition and strengthening capability of stainless steels with 13 – 17 % Cr

The paper considers the study of the features of structure and phase transformations in high-strength, resistant to carbon dioxide corrosion, complex alloyed steels of martensitic, austenitic-martensitic and martensitic-ferritic classes with 13 – 17 % Cr. Influence of the alloying on crystallization and solid state phase transformations was revealed in the temperature range of hot deformation and heat treatment using thermodynamic modeling and experimental study. The effect of quenching temperature on the phase composition and microstructure was analyzed as a result of X-ray diffraction phase analysis, optical and transmission electron microscopy. It was found that increase of nickel content leads to growth of retained austenite fraction resulting in significant decrease of yield strength along with high tensile strength and elongation. To obtain predominantly martensitic microstructure in martensitic-austenitic steel, the multistage heat treatment is proposed including quenching, intermediate annealing for precipitation of dispersed carbides and tempering forming final mechanical properties. The composition of precipitated carbides was evaluated by X-ray microanalysis. The results of the tensile test for steels with martensitic and martensitic-ferritic microstructure showed that required strength grade (σ0.65 ≥ 862 MPa; σв ≥ 931 MPa) was reached after heat treatment including quenching and tempering. Multistage heat treatment including quenching, intermediate annealing and final tempering was resulted in required strength properties of high-nickel martensitic-austenitic steel with 15 % Cr.

Evaluation of welded joints of dissimilar titanium alloy Ti-5Al-2.5Sn and stainless-steel 304 at different multi-interlayer modes

Products manufactured by joining titanium and stainless steel are of great attention to the modern-day industries (aerospace and nuclear) due to their several benefits like high strength, low cost, and corrosion resistance. However, it is difficult to join these alloys owing to the formation of TiFe, Ti2Fe, and TiFe2 compounds which damage their mechanical properties. This study aims to evaluate the microstructural and mechanical properties of titanium alloy Ti-5Al-2.5Sn and stainless steel 304 joints. Joining was performed through pulse–gas tungsten arc welding (P-GTAW) by inserting the Nb-Cu multi-interlayer. The effects of welding speed, two multi-interlayer application modes, and arc offset on the microstructure and mechanical properties such as tensile strength and microhardness were investigated. The mechanical properties were evaluated through tensile and hardness tests while microstructural analysis using scanning electron microscopy (SEM) supported by electron dispersive spectroscopy (EDS). The results revealed that sound and high-quality welds were achieved using a multi-interlayer, which inhibited the formation of TiFe, Ti2Fe, and TiFe2 brittle intermetallic compounds (IMCs). Maximum joint strength of 327 MPa was achieved at a welding speed of 200 mm min−1, mode of multi-interlayer (Nb used as a foil and Cu as a wire) at no arc offsetting, whereas a low joint strength was obtained in the multi-interlayer mode (Nb and Cu both as foils), and arc offset towards SS. The SEM and EDS results revealed that a Cu solid solution was obtained in the fusion zone, which improved the tensile strength. Joint fracture surface analysis indicated that ductile fracture was obtained for high-strength and brittle fracture for the low-strength weld. It is evident that high hardness (400 HV) was obtained at a low welding speed (150 mm min−1) and an arc offset to the stainless steel side owing to the formation of TiCu and Ti2Cu phases, as revealed by the x-ray diffraction phase analysis.

Influence of high-temperature ion irradiation on nanostructured TiAlN coatings

Nanostructured TiAlN coatings were formed on AISI 304 stainless steel substrates by reactive magnetron sputtering. The studied TiAlN coatings were irradiated with Ar+ ions with an energy of 200 keV in the fluence range from 2.5 ⋅ 1016 to 2.0 ⋅ 1017 ion per 1 cm2 at a temperature of 480 °C. Using energy-dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffraction phase analysis, the elemental composition, structural-phase state and morphology of the initial and irradiated coatings were studied. Nanoindentation of the obtained structures was carried out according to the method of Oliver and Pharr, the nanohardness (Н) and Young’s modulus (E) were determined, and the impact strength of the coatings under study was calculated as the H/E∗ ratio. The formation of a single-phase structure of the (Ti, Al)N solid solution in the coatings initial state has been detected. The effect of selective sputtering of the lightest component – nitrogen – from the coatings was found. Up to an irradiation fluence of 1.0 ⋅ 1017 ion per 1 cm2, no significant changes were revealed in the structural-phase state of the coatings. When irradiated with a fluence of 2.5 ⋅ 1016 ion per 1 cm2, an improvement in the TiAlN coatings strength properties complex was observed. It has been found that nanostructured TiAlN coatings are radiation-resistant up to an irradiation fluence of 2.0 ⋅ 1017 ion per 1 cm2, at which the onset of segregation of the (Ti, Al)N solid solution as the main phase of the coatings and blistering effect is observed.

Studies on Recovery of Valuable Metals by Leaching Lead–Zinc Smelting Waste with Sulfuric Acid

Germanium-containing residues (GCR) are a secondary resource rich in zinc (Zn) and germanium (Ge) produced in the Zn pyrometallurgical process and an important raw material for recovering Zn and Ge. To recycle the residue by hydrometallurgy, sulfuric acid is used to leach the residue under normal pressure. In this study, the experimental conditions (leaching temperature, leaching time, liquid/solid (L/S) mass ratio and initial acidity) were optimized through the experimental design to make the optimized experimental conditions consistent with the current industrial production conditions, so as to maximize the leaching rate of Zn and Ge, and the main reasons for the low leaching rate of germanium were analyzed. The results show that the optimum reaction conditions are as follows: initial acidity 160 g·L−1, leaching temperature 90 °C, L/S mass ratio 5:1, leaching time 60 min and stirring speed 400 r·min−1. Under the optimum reaction conditions, the leaching rates of Zn and Ge are 83.22% and 77.29%, respectively. The reason for the low leaching rates of Zn and Ge in GCR was obtained through atmospheric leaching experiment, electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and chemical phase analysis. GCR is mainly composed of phases such as zincite (ZnO), galena (PbS), wurtzite (ZnS) and anglesite (PbSO4), and the main elements are Zn, lead (Pb), germanium (Ge), oxygen (O), sulfur (S), silicon (Si), aluminum (Al) and Fe. This study can provide a certain reference value for researchers, in order to provide a reference for the large-scale recycling of Zn and Ge resources in the future.

Annealing hardening behaviour of cold rolled Al0.5CoNiCu high-entropy alloy

The usually, softening occurs when metals are annealed, while for some special metals or alloys, the abnormal phenomenon of annealing hardening will occur. By means of X-ray diffraction (XRD), metallographic (OM) observation, transmission electron microscopy (TEM) and hardness test, the microstructure and hardness of 79% cold rolled Al0.5CrFeCoNiCu high entropy alloy was studied after isothermal annealing for 1 hour at different temperatures, which revealed the cause of annealing induced hardening of the alloy. The results show that the homogenized high-entropy alloy is a face centered cubic (FCC) biphasic structure with close lattice constant. After annealing at 300-750°C, the microhardness of the alloy is higher than that of the cold rolled alloy (399hv); With the increase of annealing temperature, the hardness increased first and then decreased. After annealing at 500 °C for 1 hour, the hardness reached the peak (489hv). XRD phase analysis shows that the alloy will precipitate body centered cubic (BCC) phase when annealed at 500-950°C and precipitate σ phase when annealed at 700-850 °C; In addition, when annealed at 650°C and above, the dislocation recovery speed in FCC phase is accelerated and recrystallization will occur, resulting in rapid softening of the alloy. TEM observation showed that there were L12 nano-precipitates with ordered structure in the FCC phase of the matrix. Therefore, the reason for the hardness peak of the alloy annealed at 500°C is the joint action of dislocation strengthening and precipitation strengthening (L12 and BCC phases).

Solid-state synthesis of the Zn2SiO4:Mn phosphor: Sequence of phase formation, localization and charge state of Mn ions in the intermediate and final reaction products

The phase and structure formation of the Zn2SiO4:Mn phosphor during solid-state synthesis in air from ZnO, SiO2, and Mn2O3 was studied by differential thermal, thermogravimetric, X-ray phase diffraction, and luminescent analyses. It has been shown that the first product of their interaction is a solid solution with the spinel structure (Zn1-хMn2+х)Mn3+2O4 (700°С); with an increase in temperature, ZnMn3+2O4 heterolite is formed. When heated to 900°С, willemite Zn2SiO4 appears along with heterolite. At higher temperature, the interaction of ZnMn3+2O4 with SiO2 leads to the formation of Zn2SiO4:Mn with an impurity of rhodonite Mn2+SiO3. A further increase in temperature activates the interaction of willemite, heterolite, rhodonite, silicon and zinc oxides. At about 1250 °C, this heterophase mixture forms the final single-phase product - the Zn2SiO4:Mn phosphor.

Multi-Elemental Coatings on Zirconium Alloy for Corrosion Resistance Improvement

Zirconium alloys are commonly used as a cladding material for fuel elements in nuclear reactors. This application is connected with zirconium alloy’s good resistance to water corrosion and radiation resistance under normal working conditions. In the case of severe accident conditions, the possibly very fast oxidation of zirconium alloys in steam or/and air atmosphere may result in the intense generation of hydrogen and explosion of the hydrogen oxide mixture. The development of a solution to minimize the aforementioned risk is of interest. One of the actual concepts is to improve the oxidation resistance of Zr alloy cladding with protective coatings. This study aimed to develop, form, and investigate new coatings for zirconium alloy Zry-2. Multi-elemental Physical Vapour Deposition (PVD) coatings with Cr, Si, and Zr were considered for Institute of Nuclear Chemistry and Technology) INCT as corrosion protective coatings for nuclear fuel claddings. Heat treatment at 850–1100 °C/argon, air oxidation processes at 700 °C/1–5 h, and a long-term corrosion test in standard conditions for Pressure Water Reactor (PWR) reactors (360 °C/195 bar/water simulating the water used in PWR) were carried out. Initial, modified, and oxidized materials were characterized with Scanning Electron Microscopy (SEM) (morphology observations), Energy Dispersive Spectroscopy (EDS) (elemental composition determination), and X-ray Diffraction (XRD) (phase composition analysis). Slower oxidation processes and a smaller oxidation rate, in the case of modified material investigations, were observed, as compared with the unmodified material. The obtained results displayed a protective character against the oxidation of formed layers in the defined range of parameters in the process.

Determination of optical and structural properties of lithium silicate ceramics with different ratios of Sm doped

In this study, the synthesis and luminescence characterization of Samarium (Sm 3+ ) doped lithium metasilicate (Li 2 SiO 3 ) phosphor ceramic were investigated. TSL, RL, and PL spectrums were discussed. It was concluded that the materials showed typical luminescence and optical properties. RL measurements of Sm 3+ doped (0.156%mol) and undoped Li 2 SiO 3. • Lithium silicate materials with doped/undoped were synthesized using solid state reaction method. • Investigation of XRD and SEM analysis were performed. • RL, PL and TSL spectrums are investigated. • Some optical and physical properties were discussed. In this study, the synthesis and luminescence characterization of Samarium (Sm 3+ ) doped lithium metasilicate (Li 2 SiO 3 ) phosphor ceramic were investigated. It was presented and discussed the results obtained on the luminescence and other optical studies such as X-ray diffraction (XRD), optical absorption and luminescence properties of Li 2 SiO 3 :Sm 3+ phosphor ceramic. The Li 2 SiO 3 compound was shown a characteristic phase in XRD. The doping in the lithium compound was not having a significant effect on the basic crystal structure of the material. The maximum photoluminescence (PL) emission for Sm 3+ doped Li 2 SiO 3 was observed at 554, 583, 641, 725 nm and bore resemblance to the visible region of the spectrum. The glow curves of all synthesized materials have a complex peak structure after being irradiated with a 90 Sr– 90 Y beta source. In addition, the peak between 400 and 600 nm was seen in the radioluminescence (RL) spectrum because of a wide peak thought to be caused by silicate.

Investigation of Magnetic and Photocatalytic Properties of CoFe2O4 Doped La3+, Nd3+, I3+

Cobalt ferrites are widely used for permanent magnets, magnetic fluids, microwave devices, high density information storage and environmental technologies. The properties of nanosized magnetic materials strongly depend on the shape, size, and phase composition of the particles. The great interest of researchers in nanosized materials in recent years is associated with the possibility of changing the properties of magnetic materials by controlling the particle size and distribution of cations over sublattices in ferrite [1].Nanoparticles of doped cobalt ferrite showed improved physicochemical characteristics compared to individual components due to the synergistic effect of the mutual presence of cations. Currently, various technologies for producing ferrites are used. However, to obtain a single-phase product, calcination of the precursors at a temperature of 1300-1500 0C is required, which causes agglomeration and sintering of the product. The use of modern methods of electrochemical synthesis is the basis for obtaining ferrites from transition materials with a given set of properties. A characteristic recent trend is the development of new technologies and compositions for the production of precisely nanodispersed ferrites [2].The purpose of this work is to study the possibility of using contact low-temperature nonequilibrium plasma for the synthesis of cobalt ferrites doped with La3+, Nd3+, I3+ cations, to establish a relationship between the cationic composition of ferrites and its phase composition, magnetic and structural characteristics.Ferrites were synthesized in the form of nanoparticles using contact nonequilibrium low temperature plasma in an electrochemical reactor. The crystalline microstructure of the samples was revealed by X-ray diffraction and X-ray phase methods. The magnetic characteristics were determined from hysteresis loops. The EPR spectra were obtained on a Radiopan SE/X-2543 radiospectrometer. To characterize the EPR signals, the intensity and width of the signal, and the resonant frequency were used. The visualization of the dependences of the technological characteristics of La3+-Nd3+-I3+ ferrites on the cationic composition was carried out by the simplex method using the STATISTICA 12 program.It has been established that the nature of the rare-earth metal cation in cobalt ferrite directly determines the magnetic and photocatalytic properties of spinel ferrites. The effect of the mutual influence of the content of cations on the saturation magnetization and coercive force is determined. The most influencing factor is the content of neodymium cations. Low values of the coercive force for Mn-Zn and Co-Zn ferrites and high values for the entire range of Co-Mn ferrites are established. An increase in the content of cobalt cations leads to an increase in the saturation magnetization value of Co-Mn ferrites. The EPR spectra show that the values of the resonance field and linewidth in the EPR spectrum correlate with the value of magnetic saturation.Simultaneous substitution of Nd3+ and La3+ in CoFe2O4 nanoparticles affected the structure, magnetic and photocatalytic properties. Structural parameters were investigated and calculated using X-ray diffraction studies. The magnetization analyzes were carried out at room temperature. Various magnetic parameters have been obtained and discussed, including remanence (Mr), coercive force (Hc), saturation magnetization (Ms), squareness ratio (SQR=Mr/Ms) and magnetic moment (nB). An increase in Mr, Ms, Hc and nB was found at lower concentrations of Nd3+ and La3+. An increase in the content of Nd3+ cations leads to a significant increase in the coercive force. The analysis of photocatalytic activity in the reaction of isolation of furacilin showed the best results (destruction rate 98%, time 40 minutes) for the ternary composition.References Caldeira, Luis Eduardo, et al. "Correlation of synthesis parameters to the structural and magnetic properties of spinel cobalt ferrites (CoFe2O4)–an experimental and statistical study." Journal of Magnetism and Magnetic Materials550 (2022): 169128.Lu, Yuzheng, et al. "Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles." Ceramics International2 (2022): 2782-2792.

Morphology, Phase and Chemical Analysis of Leachate after Bioleaching Metals from Printed Circuit Boards.

The article presents the assessment of solutions and dried residues precipitated from solutions after the bioleaching process of Printed Circuit Boards (PCB) utilizing the Acidithiobacillus ferrooxidans. The obtained dried residues precipitated from bioleaching solution (leachate) and control solution were tested using morphology, phase, and chemical composition analysis, with particular emphasis on the assessment of crystalline and amorphous components. The analysis of the dried residues from leachate after bioleaching as well as those from the sterile control solution demonstrated a difference in the component oxidation—the leachate consisted of mainly amorphous spherical particles in diameter up to 200 nm, forming lacy aggregates. In the specimenform control solution larger particles (up to 500 nm) were observed with a hollow in the middle and crystalline outer part (probably Fe2O3, CuFeS2, and Cu2O). The X-ray diffraction phase analysis revealed that specimen obtained from leachate after bioleaching consisted mainly of an amorphous component and some content of Fe2O3 crystalline phase, while the dried residue from control solution showed more crystalline components. The share of the crystalline and amorphous components can be related to efficiency in dissolving metals during bioleaching. Obtained results of the investigation confirm the activity and participation of the A. ferrooxidans bacteria in the solubilization process of electro-waste components, with their visible degradation–acceleration of the reaction owing to a continuous regeneration of the leaching medium. The performed investigations allowed to characterize the specimen from leachate and showed that the application of complementary cross-check of the micro (SEM and S/TEM) and macro (ICP-OES and XRD) methods are of immense use for complete guidance assessment and obtained valuable data for the next stages of PCBs recycling.

Observation of bulk plasticity in a polycrystalline titanium alloy by diffraction contrast tomography and topotomography

The mechanical properties of polycrystalline metals are governed by the interaction of defects that are generated by deformation within the 3D microstructure. In materials that deform by slip, the plasticity is usually highly heterogeneous within the microstructure. Many experimental tools can be used to observe the results of slip events at the free surface of a sample; however, there are only a few methods for imaging these events in the bulk. In this article, the imaging of bulk slip events within the 3D microstructure are enabled by the combined use of X-ray diffraction contrast tomography and topotomography. Correlative measurements between high-resolution digital image correlation, X-ray diffraction contrast tomography, topotomography and phase contrast tomography are performed during deformation of Ti-7Al to investigate the sensitivity of the X-ray topotomography method for the observation of slip events in the bulk. Much larger neighborhoods of grains were able to be mapped than in previous studies, enabling quantitative measurements of slip transmission. Significant differences were observed between surface and bulk grains, indicating the need for 3D observations of plasticity to better understand deformation in polycrystalline materials.

Morphological and Structural Transformations of Fe-Pd Powder Alloys Formed by Galvanic Replacement, Annealing and Acid Treatment.

In this article, we report the preparation and structural features of Fe-Pd powder alloys formed by galvanic replacement, annealing and selective dissolution of iron via acid treatment. The alloys were studied by the X-ray diffraction phase analysis, Mössbauer spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The Fe@Pd core–shell particles were obtained by a galvanic replacement reaction occurring upon treatment of a body-centered cubic (bcc) iron powder by a solution containing PdCl42− ions. It was found that the shells are a face-centered cubic (fcc) Pd(Fe) solid solution. HCl acid treatment of the Fe@Pd core–shell particles resulted in the formation of hollow Pd-based particles, as the bcc phase was selectively dissolved from the cores. Annealing of the Fe@Pd core–shell particles at 800 °C led to the formation of fcc Fe-Pd solid solution. Acid treatment of the Fe-Pd alloys formed by annealing of the core–shell particles allowed selectively dissolving iron from the bcc Fe-based phase (Fe(Pd) solid solution), while the fcc Fe-rich Fe-Pd solid solution remained stable (resistant to acid corrosion). It was demonstrated that the phase composition and the Fe/Pd ratio in the alloys (phases) can be tailored by applying annealing and/or acid treatment to the as-synthesized Fe@Pd core–shell particles.

Phase diagram study and thermodynamic assessment of the Y2O3-YF3 system

The phase diagram of the Y2O3-YF3 system up to 1973 K was investigated using a classical equilibration/quenching experiment and differential thermal analysis (DTA). Equilibrium phases were confirmed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) phase analysis. For the very first time, the entire range of the phase diagram of yttrium oxy-fluoride system up to 1973 K was experimentally determined. Cubic-Y2O3 phase dissolves more than 5 mol% of YF3 at 1973 K. The melting points of YOF and vernier phases are found to be higher than 1973 K and their steep liquidus in the YF3-rich region are determined. Based on new experimental phase diagram data and thermodynamic property data in the literature, the Y2O3-YF3 system was thermodynamically modeled by the CALculation of PHAse Diagram (CALPHAD) method. As applications of the thermodynamic database, metastable solubilities of YF3 in Y2O3 during plasma etching process were calculated.

The effect of Ti and B4C on the microstructure and properties of the laser clad FeCoCrNiMn based high entropy alloy coating

FeCoCrNiMnTix(B4C)y high entropy alloys (HEAs) coatings were laser cladded on Q355 steel using coaxial powder feeding laser 3D printing system by adjusting the additive ratio of pure Ti powder and B4C powder into the pre-alloyed spherical equi-atomic FeCoCrNiMn powder. Hardness, X-Ray Diffraction (XRD) phase composition, Scanning Electron Microscope (SEM) morphology, Energy Dispersive X-ray Spectroscopy (EDS) and wear resistance of the HEAs coatings were examined. The FeCoCrNiMnTix HEAs coatings (x = 0.5, 0.6, 0.8, 1.0) composed of fcc, bcc1 and bcc2 phase, The hardness increased as the Ti adding content increased, which may be attributed to the solution strengthening effect and promoting effect to the formation of bcc1 and bcc2 phase. The addition of B4C induced the formation of compound borides and carbides, and the decreasing of Ti solution in fcc and bcc phases. The phase composition of the FeCoCrNiMnTi0.6(B4C) y coating was mainly fcc, bcc2, borides and carbides. The increase of B4C improved the hardness and bcc2 content in FeCoCrNiMnTi0.6(B4C) y HEAs coating, and the wear resistance increased also to some extent. Among four FeCoCrNiMnTi0.6(B4C)y HEAs coatings (y = 0, 0.2, 0.4 and 0.6), FeCoCrNiMnTi0.6(B4C)0.4 HEAs coatings had the best wear resistance.

Effect of vanadium doping on the structural and optical characteristics of nano ZnCdS

Nano Zn0.75-xCd0.25VxS (0 ≤ x ≤ 0.2, step 0.05) samples were formed by the molten salt solid state reaction method at low temperature. Synchrotron x-ray diffraction phase identification revealed biphasic ZnS structure for all samples, cubic zinc blende and hexagonal wurtzite. Rietveld analysis was applied to determine the effect of V-doping on the percentage of each phase and their structural and microstructural parameters. The existence of V ions in the Zn0.75Cd0.25S (ZnCdS) lattice is confirmed by Fourier-transform infrared spectroscopy (FTIR) technique. Utilizing the UV–vis diffuse reflectance spectroscopy, the effect of V-doping on the absorption, reflectance, refractive index, extinction coefficient and electric properties of ZnCdS were studied in detail. The optical bandgap (Eg) significantly decreased from 2.82 eV for zero V-doping to 2.55 eV for x = 0.2. Also, the refractive index decreased sharply in the wavelength region 450–900 nm. ZnCdS sample has anomalous dispersion behavior while the doped samples have anomalous and normal dispersion features. The photoluminescence intensity and emitted colors in the UV and visible regions were affected by the amount of doping.

Elimination of Composition Segregation in 33Al-45Cu-22Fe (at.%) Powder by Two-Stage High-Energy Mechanical Alloying.

In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying was conducted in two stages: at the first stage, a Cu+Fe powder mixture was ball-milled for 90 min; at the second stage, Al was added, and the milling process was continued for another 24 min. The main products of mechanical alloying formed at each stage were studied using X-ray diffraction phase analysis, Mössbauer spectroscopy, transmission electron microscopy, and energy-dispersive spectroscopy. At the end of the first stage, crystalline iron was not found. The main product of the first stage was a metastable Cu(Fe) solid solution with a face-centered cubic structure. At the second stage, the Cu(Fe) solid solution transformed to Cu(Al), several Fe-containing amorphous phases, and a spinel phase. The products of the two-stage process were different from those of the single-stage mechanical alloying of the ternary elemental powder mixture; the formation of undesirable intermediate phases was avoided, which ensured excellent composition uniformity. A sequence of solid-state reactions occurring during mechanical alloying was proposed. Mesopores and a spinel phase were the features of the two-stage milled material (both are desirable for the target catalyst).