Fe Al Ti Research Articles

Heavy metal migration and lithium isotope fractionation under extreme weathering of basalt on tropical Hainan Island, China

Basalt weathering can cause heavy metal enrichment in soils, and lithium isotopes serve as an effective tracer for this weathering process. However, the relations among weathering intensity, heavy metal migration, and Li isotope fractionation remain unclear. We conducted systematic examinations of a basalt weathering profile on tropical Hainan Island in China. The characteristics of mineralogy, elemental and Li isotopic geochemistry indicate that the profile has undergone changes from initial to advanced and ultimately extreme weathering stages. The corresponding dominant minerals are primary minerals, clay minerals such as kaolin-group, and the Al–Fe–Ti (hydro)oxides. The variations of Fe-group heavy metals within the profile are very similarly to that of Fe, exhibiting a pattern of loss-gain-loss. Newly formed secondary minerals preferentially incorporate lighter 6Li, leading to a gradual increase in Li content and a decrease in δ7Li. Due to the high δ7Li value of rainwater input, the ongoing impact of secondary mineral adsorption is partially counteracted. This results in the δ7Li of laterite and topsoil being maintained within a narrow range (−3.2‰ ∼ −1.9‰), despite the broader variation observed across the entire profile (−3.2‰ ∼ +2.8‰). Comparing basalt weathering profiles in different climatic zones reveals a very complex Li isotope behavior and its controlling factors. Therefore, it is essential to carefully evaluate the influence of atmospheric input, secondary mineral adsorption, dissolution, and redeposition processes on Li isotopes. Throughout the entire profile, Cr, Ni, and Cu exhibit enrichment relative to soil background values, indicating that the weathering of tropical basalt may pose potential environmental risks for these elements.

Physicochemical and Service Properties of Nb–Si–Al–Fe–Ti Alloys

Physicochemical and Service Properties of Nb–Si–Al–Fe–Ti Alloys

Microstructure and tribocorrosion behaviors of Fe–Al–Ti coatings prepared by the aluminothermic reaction

To improve the tribocorrosion resistance of 316L stainless steel in acidic media, Fe–Al–Ti coatings were prepared on 316L substrate by self-propagating high-temperature synthesis (SHS) using an aluminothermic reaction. The effects of Ti content on the tribocorrosion behaviors of Fe–Al–Ti coatings in 0.5 mol/L H2SO4 solutions were investigated. The Fe–Al–Ti coatings exhibited a multi-phase microstructure. The open circuit potential (OCP) of the Fe–Al–Ti coatings and 316L substrate decreased significantly with the onset of sliding, indicating a strong wear-corrosion synergistic effect. The hardness and tribocorrosion resistance of Fe–Al–Ti coatings increase with increasing the Ti content. The tribocorrosion volume loss of the Fe–25Al–25Ti coating was about one order of magnitude lower than that of the 316L substrate. The Fe–25Al–25Ti coating was more suitable as a tribocorrosion-resistant material than the 316L substrate.

Thermodynamic Properties Prediction of Fe–Al–Ti Alloys Based on Atom and Molecule Coexistence Theory

Thermodynamic Properties Prediction of Fe–Al–Ti Alloys Based on Atom and Molecule Coexistence Theory

Fundamental Research on Evolution of TiN in Fe–Al–Ti–O–N Alloy During Isothermal Holding

Fundamental Research on Evolution of TiN in Fe–Al–Ti–O–N Alloy During Isothermal Holding

Geochemical study of Al–Fe–Ti enrichment in rock weathering: Implications for the recognizing of igneous protolith and the enrichment of REE in soil profile

Chemical weathering of rocks has been investigated since 1960, and lithogeochemistry has commonly been used since 1980 to determine the protoliths of heavily weathered igneous rocks. However, it is still quite difficult to uniquely identify the laterite originating from a potassic basaltic rock, which formed in the anorogenic/within-plate environment (e.g., low silica trachytic rock, phonolite, and tephri-phonolite). These difficulties occur because the within-plate basaltic rocks contain a relatively high Zr concentration; therefore, laterites with high Zr/Ti ratios are often identified as dacite or rhyolite. Besides that, using Zr/Ti is also difficult to distinguish between ultramafic and basaltic rocks. This study has developed the “overlaid ternary DOS (Degree of Saprolitization)" to solve those problems by overlaying the existing ternary DOS to recognize the igneous rock lithology on lateritic profiles released from ultramafic, mafic/basaltic, intermediate, and felsic rocks.The study of drill core laterites from Western Sulawesi/WS (Mamuju district) in hole-A and hole-B characterized by high Zr (1170–2553 ppm), relatively high TiO2 (1.68–2.99%), and high Zr/Ti ratio values (Zr/Ti > 0.0833); and they are recognized as weathering of basaltic rock. While laterite from West Java (Dago Atas Bandung/DAB) released from weathering of andesitic rock (Zr: 148 ppm; TiO2: 1.49%; Zr/Ti: 0.0167). The enrichment of REE (rare earth element) in the hole-B laterite profile occurred on the surface of topsoil (1st meters) to a depth of the 3rd meters (TRE2O3(avg): 2359 ppm; TREY: 2005 ppm), and a slight enrichment in the 5th to 7th meters (TRE2O3: 1688–1933 ppm; TREY: 1437–1647 ppm). This study shows that the enrichment of REE in the soil horizon does not directly correspond to the Ce-anomaly.

A re-examination of the liquidus surface of the Al–Fe–Ti system

Abstract The liquidus surface of the Al –Fe –Ti system has been reexamined. 34 different alloys have been studied by differential thermal analysis, and the temperatures of invariant reactions have been determined. By examining the as-cast samples by optical microscopy, X-ray diffraction and energy-dispersive spectrometry in a scanning electron microscope, the crystal structures and chemical compositions of the primary phases and two-phase aggregates have been established. In some cases, additional investigations were carried out in the transmission electron microscope. From the combined results of these investigations the solidification paths of the alloys were established leading to a revised representation of the liquidus surface of the Al –Fe –Ti system. A reaction scheme has been set up which shows phase equilibria that are consistent with previous solid-state isothermal sections.

Influence of iron, aluminum, calcium, titanium and vanadium impurities removal from silicon based on Cu-catalyzed chemical leaching

In this work, silicon purifying process based on the novel Cu-catalyzed chemical leaching (CuCCL) treatment has been investigated as a function of different silicon particle size, HF concentration, leaching time, H2O2 concentration, Cu(NO3)2 concentration and leaching temperature. Typical impurity precipitate in silicon was analyzed, which revealed that the main impurities of Fe, Al, Ca, Ti, and V mainly exist as Si2Fe, Si–Fe–Al, Si–Fe–Al–Ca, and Si–Fe–Al–Ti–V phases in the MG-Si feedstock. The results showed that the main impurities Fe, Al, Ca, Ti, and V can be effectively eliminated by the CuCCL treatment, especially for Ca, Ti and V. In the appropriate experiment conditions, the removal of main impurities Fe, Al, Ca, Ti, and V from MG-Si significantly reached to 99.38%, 98.64, 100%, 100%, and 100%, respectively. It was found that the impurities on the silicon facilitated the formation of porous structures during the CuCCL process, and the generated porous structures further exposed more impurities to the acid etchants, which promote the impurity removal from silicon. Furthermore, the leaching behaviors of impurity precipitates in the CuCCL process were obtained through revealing their evolution during deposition and etching steps. The high-efficient silicon purification effect of this study may bring some new strategy for achieving the low-cost solar grade silicon.

Saline slag waste as an aluminum source for the synthesis of Zn–Al–Fe–Ti layered double-hydroxides as catalysts for the photodegradation of emerging contaminants

In this work, aluminum extracted from saline slag waste is valorized to create a layered double-hydroxide series containing zinc and various proportions of aluminum/titanium. Materials were synthesized by the co-precipitation method with an Me2+/Me3+ molar ratio of 3:1 and tested for the removal of diclofenac and salicylic acid from water under UV radiation. The incorporation of 5 wt% iron by wet impregnation is evaluated. In addition, another series of zinc, aluminum/iron materials with and without 5 wt% impregnated titanium are tested as catalysts for comparison. Structural characterization and comparison of the two series was performed by powder X-ray diffraction (PXRD), nitrogen adsorption at 77 K, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) measurements. The uncalcinated samples had a typical hydrotalcite structure with a high crystallinity; the presence of ZnO, ZnFe2O4 or Fe3O4 was found after calcination. The specific surface areas of the dried samples ranged from 78 to 199 m2/g, being highest for Zn6Al0.5Ti1.5. Overall, the results showed that the ZnAlTi series were more effective catalysts than ZnAlFe for photodegradation of the emerging contaminants diclofenac and salicylic acid, under UV light at 298 K, considering two concentrations of the organic molecules (5 and 50 μmol/dm3).

Effects of Alloying Elements (Ti and xAl) on the Electrochemical Corrosion Behaviour of Iron-Based Alloys in Corrosive Solutions of Different pH

In this research, the effects of Ti addition, increased Al content (x = 12, 19 and 28 wt%) and pH of the corrosive solution on the corrosion behaviour of Fe, Fe–12Al, Fe–19Al, Fe–28Al and Fe–7.7Al–8.5Ti alloys were electrochemically studied through the potentiodynamic polarization (PDP), open-circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. In all test solutions, the OCP reported generally that the open-circuit potential shift is positive compared to the Fe-alloy. The PDP results confirmed that the investigated alloys record a decrease in the corrosion rate in the following order: Fe–7.7Al–8.5Ti < Fe–xAl < Fe. Also, the corrosion current density (icorr) decreases with increasing the Al content. The experimental impedance data clearly confirmed that, increased Al content in the binary Fe–xAl alloys increases the corrosion resistance; moreover, ternary Fe–Al–Ti was superior to Fe–xAl against corrosion where more thicker and resistant passive layer is formed on the Fe–Al–Ti alloy surface. For all alloys, the corrosion resistance reaches maximum passivation in neutral rather than acidic or basic solution. The charge-transfer resistance, Rct, was compared with the polarization resistance, Rp, for accurate analysis of the EIS and PDP results. The surface analysis (SEM/EDAX) showed the participation of the different alloying elements in the protection according to the alloy constituents. It turned out that presence of Al and Ti increase the corrosion resistance. For industrial applications, the results lead to the recommendation of the Fe–7.7Al–8.5Ti alloy in the industrial chemical processes which require high corrosion resistance as that of halides resistance.

Origin of the phase separation into B2 and L21 ordered phases in X–Al–Ti (X: Fe, Co, and Ni) alloys based on the first-principles cluster variation method

The phase separation behaviors from a single B2 ordered phase into two separate B2 and L21 ordered phases in X–Al–Ti (X: Fe, Co, and Ni) alloys are analyzed utilizing the cluster variation method (CVM), based on interaction energies derived from electronic band structure calculations. A cubic approximation of the CVM is adopted for X2Al2−xTix () alloys limiting the interchange between Al and Ti atoms on the - and -sublattices of an L21 ordered structure with X atoms fixed on the -sublattice. The phase stabilities of the B2 and L21 structures are examined, and phase diagrams at the pseudo-binary section, XAl–XTi, are determined. The two-phase regions of the B2 and L21 phases (i.e. phase separation behavior) are successfully produced in Co– and Ni–Al–Ti alloy systems, and no phase separation is observed in the Fe–Al–Ti alloy. The origins of phase separation in the Co– and Ni–Al–Ti alloys are mechanical instability and a combination of mechanical instability and chemical repulsions of unlike pairs, respectively.

Investigation of Wear and Corrosion Behaviour of AISI 316 L Stainless Steel Coated By ESD Surface Modification

AISI 316 L austenitic stainless steel is widely used in various sectors of the industry (chemical, petro-chemical industry, paper industry, nuclear engineering, dairy equipment and medical field) because of its good corrosion resistance and biocompatibility. In contrast to these superior properties, it has a low hardness and poor wear performance, thus, limiting its use in some areas of industry. As a result of progress in science and technology, the expectation of superior properties from materials has increased and the surface modification has become an important part of this development. Amongst many coating processes, Electro-spark Deposition (ESD) is a micro-bonding process that is used to deposit a stronger, more robust and durable coating layer on a metallic substrate. This method can also be used to repair damaged parts, tools or equipment or to extend the tool and equipment life. In this study, the surface of AISI 316 L stainless steel was coated with WC and Ti6Al4V by ESD method. Morphology and microstructure of the deposited layers were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Surface hardness distributions were determined with a micro hardness tester. XRD analysis revealed that Fe–α, Fe–γ, W2C, Cr–Ti, Al–Fe–Ti phases exist on the deposited layers. The wear behavior of the coated surfaces was carried out by ball-on-disc wear method using WC-Co ball bearing with a diameter of 8 mm for a sliding distance of 250 meters at a sliding rate of 0.3 m/s under a dry condition using a load of 5 N. Corrosion behavior of coated surfaces i.e. Tafel extrapolation and linear polarization methods were investigated for the duration of 1 h in the SBF (Simule Body Fluid) solution. Morphology of layers formed on steel surface was examined by SEM microscope. Wear tests showed that AISI 316 L stainless steel has a low surface hardness but wear resistant coatings improved this property. The wear rate of coated AISI 316 L stainless steel decreased by 3–10 times with respect to the type of coating. The electrochemical experiments showed that the expected improvement was not achieved due to the high corrosion resistance of AISI 316 L stainless steel. However, the weakness of the surface hardness was partly replaced by an acceptable compromise from corrosion resistance.

Forms of trace arsenic, cesium, cadmium, and lead transported into river water for the irrigation of Japanese paddy rice fields

In this study, we focus on the behavior of geogenic, toxic trace elements, particularly As, Cs, Cd, and Pb, during their transportation in two rivers for irrigation commonly used in monsoon Asia; one river originates from an active volcano, Mt. Asama, and the other originates from a currently inactive volcano, Yatsugatake Mountains in Nagano, Japan. These rivers were investigated to understand the role of river water as a pollutant of rice and other aquatic plants (via irrigation) and aquatic animals. The results indicated that the behavior of toxic trace elements in river water are likely controlled by their interactions with particulate Fe, Al, and Ti compounds. The majority of Pb and Cd is transported as particulate matter with Fe, Al, and Ti, while the majority of As is transported in the dissolved form, predominantly as arsenate, with low abundance of particulate matter. Cs is transported either as the dissolved form or as particulate matter in both rivers. The investigated elements are transported in the rivers as particulate and dissolved forms, and the ratio of these forms is controlled by the pH and presence of particulate Fe, Al, and Ti phases in the river water. With respect to Cs in both rivers, the parameter governing the concentration and transportation of Cs, in the bimodal form (i.e., particulate and dissolved forms), through the river possibly shifts from sorption to pH by particulate Fe–Al–Ti, according to the abrupt increase in the concentration of Cs in the river. The chemical attraction of particulate Fe–Al–Ti for Cs is weaker than that for Pb and Cd, indicating that the lower electronegativity of Cs weakens the chemical attraction on a colloid for the competitive sorption with the other trace elements. The different relationships between As and Fe in the river and in the irrigation water and soil water, as well as those in paddy rice, suggested that As in paddy rice is not directly derived from As in the irrigation water from the river under flooding.

Characterisation of multiphase ceramic coatings fabricated via laser in situ reaction technology

ABSTRACTCoatings are pre-fabricated on the China low activation martensitic (CLAM) steel via thermal spraying using Cr–Fe–Al–Ti mixed powders. Crystalline and amorphous multiphase ceramic coatings are formed by a new laser surface in situ prefabricated coatings in situ reaction technology under atmospheric environments based on the Standard Gibbs free-energy theory. The grain boundary of incomplete recrystallisation section and perfect crystallisation section can be observed clearly by high-resolution transmission electron microscopy. The Al2O3 and TiO2 are found to be formed in the crystallisation section. In addition, we adopt a new method to measure bonding strength of coating and base material, and the average shear strength is found to be 290 MPa. Further finite-element analysis shows that the shear stress distribution between the coatings and substrate is consistent with the experimental data. The average microhardness of the coatings is found to reach 1864.19 HV0.2.The coatings also exhibit the strongest liquid Pb corrosion resistance. This technique may be important in technological improvement of surfaces of the candidate structural materials for the accelerator-driven sub-critical system, which is usually applied to handle the nuclear waste under extreme conditions.

Quenching media effects on martensitic transformation, thermodynamic and structural properties of Cu–Al–Fe–Ti high-temperature shape memory alloy

We investigated the effect of three different quenching medias on martensitic transformation, thermodynamic parameters, phase equilibria, microstructural properties and microhardness values of high-temperature Cu–13.2Al–5.1Fe–1.2Ti (mass%) shape memory alloy by means of differential scanning calorimetry, X-ray diffraction, optical microscopy, scanning electron microscopy and Vicker’s microhardness measurements. Thermal analysis indicated that the transformation temperatures and thermodynamic parameters of the alloy changed depending on quenching conditions and the transformation temperature range was proportional to the cooling rate. It was found that the step-quenching treatment improved the operation temperature of alloy. Structural analysis showed that the phase components of the alloy were not affected significantly by the quenching conditions, but elemental analysis also revealed that high cooling rate leads to very significant changes on chemical compositions of the phase components. From microstructural investigations, it was found that the microstructure of alloy included a great number of voids having different sizes and forms and also different precipitates grow in these voids. In particular, it was seen that the step-quenching process caused the formation of new voids in the microstructure. Vicker’s microhardness measurements revealed that the microhardness value of the alloy was not influenced markedly by the quenching treatments.

Erratum to “Reassessment of Oxide Stability Diagram in the Fe–Al–Ti–O System” [ISIJ International, 57 (2017), No. 9, pp. 1665–1667

Erratum to “Reassessment of Oxide Stability Diagram in the Fe–Al–Ti–O System” [ISIJ International, 57 (2017), No. 9, pp. 1665–1667

Reassessment of Oxide Stability Diagram in the Fe–Al–Ti–O System

Reassessment of Oxide Stability Diagram in the Fe–Al–Ti–O System

Accelerated Discovery of Thermoelectric Materials: Combinatorial Facility and High-Throughput Measurement of Thermoelectric Power Factor

A series of processes have been developed to facilitate the rapid discovery of new promising thermoelectric alloys. A novel combinatorial facility where elements are wire-fed and laser-melted was designed and constructed. Different sample compositions can be achieved by feeding different element wires at specific rates. The composition of all the samples prepared was tested by energy dispersive X-ray spectroscopy (EDS). Then, their thermoelectric properties (power factor) at room temperature were screened in a specially designed new high-throughput setup. After the screening, the thermoelectric properties can be mapped with the possibility of identifying compositional trends. As a proof-of-concept, a promising thermoelectric ternary system, Al-Fe-Ti, has been identified, demonstrating the capability of this accelerated approach.

The properties of the nano-minerals and hazardous elements: Potential environmental impacts of Brazilian coal waste fire

Brazilian coal area (South Brazil) impacted the environment by means of a large number of coal waste piles emplaced over the old mine sites and the adjacent areas of the Criciúma, Urussanga, and Siderópolis cities. The area studied here was abandoned and after almost 30years (smokeless visual) some companies use the actual minerals derived from burning coal cleaning rejects (BCCRs) complied in the mentioned area for industry tiles or refractory bricks. Mineralogical and geochemical similarities between the BCCRs and non-anthropogenic geological environments are outlined here. Although no visible flames were observed, this study revealed that auto-combustion existed in the studied area for many years. The presence of amorphous phases, mullite, hematite and other Fe-minerals formed by high temperature was found. There is also pyrite, Fe-sulphates (eg. jarosite) and unburnt coal present, which are useful for comparison purposes. Bad disposal of coal-dump wastes represents significant environmental concerns due to their potential influence on atmosphere, river sediments, soils and as well as on the surface and groundwater in the surroundings of these areas. The present study using advanced analytical techniques were performed to provide an improved understanding of the complex processes related with sulphide-rich coal waste oxidation, spontaneous combustion and mineral formation. It is reporting huge numbers of rare minerals with alunite, montmorillonite, szomolnokite, halotrichite, coquimbite and copiapite at the BCCRs. The data showed the presence of abundant amorphous Si–Al–Fe–Ti as (oxy-)hydroxides and Fe-hydro/oxides with goethite and hematite with various degrees of crystallinity, containing hazardous elements, such as Cu, Cr, Hf, Hg, Mo, Ni, Se, Pb, Th, U, Zr, and others. By Principal Component Analysis (PCA), the mineralogical composition was related with the range of elemental concentration of each sample. Most of the nano-minerals and ultra-fine particles found in the burned coal-dump wastes are the same as those commonly associated with coal cleaning rejects, in which oxidation of sulphides plays an important role to environment and human health.

Structure and Properties of Al–Feti Powder Material Based on Mechanochemically Activated Alloy D-16 Turnings

Hot-worked powder materials (HWPM) based on a mixture of aluminum powder and turnings, prepared by combined mechanical activation of D-16 alloy turnings and ferrotitanium powder in a medium of water saturated solution of boric acid, are considered. Mechanical properties (hardness, ultimate shear strength, bending tests) and structure of the HWPM obtained are determined. On the basis of analyzing studies of the material’s structure and properties, a technology is proposed for obtaining HWPM based on agglomerates, including: treatment of D-16 alloy turnings together with ferrotitanium powder in a medium of water saturated boric acid solution, separation of the activated turning powder (ASP), preparation of a mixture of aluminum powder and ASP, and cold compaction; heating in an air atmosphere and hot stamping. This technology makes it possible to prepare materials with improved strength and hardness.