Mn Ti Research Articles

Advanced characterization of multicaloric materials in pulsed magnetic fields

The multicaloric effect is described by a temperature or entropy change of a material triggered by external stimuli applied or removed simultaneously or sequentially. The prerequisite for this is a material exhibiting multiple ferroic states. However, direct measurements of the effect are rarely reported. Now, for this reason, we built a measurement device allowing to determine the adiabatic temperature change in pulsed magnetic fields and, simultaneously, under the influence of a uniaxial load. We selected the all-d-metal Heusler alloy Ni–Mn–Ti–Co for our first test because of its enhanced mechanical properties and enormous magneto- and elastocaloric effects. Ni–Mn–Ti–Co was exposed to pulsed magnetic fields up to 10 T and uniaxial stresses up to 80 MPa, and the corresponding adiabatic temperature changes were measured. With our new experimental tool, we are able to better understand multicaloric materials and determine their cross-coupling responses to different stimuli.

Catalytic ozonation treatment of biochemically treated leachate from municipal waste solid using Ti–Mn oxide‐coated stainless steel mesh catalyst

AbstractBACKGROUNDLandfill leachate is a kind of complex organic wastewater, the discharge standard of which is difficult to meet after traditional biochemical treatment. In this work, a Ti–Mn stainless steel corrugated wire mesh (SSCWM) catalyst was prepared by the sol–gel method, which was used for the catalytic ozonation of biochemically treated leachate.RESULTSThe catalyst was characterized using scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy techniques. The data showed that the chemical oxygen demand (COD) removal efficiency of the leachate by ozone alone, SSCWM/O3, Ti–SSCWM/O3 and Ti–Mn/SSCWM/O3 system reached 55.06%, 64.44%, 68.97% and 78.43%, respectively. The catalytic effect of different layers of Ti–Mn oxide‐coated SSCWM catalyst showed that two catalytic layers had the best activity of COD removal efficiency, reaching 87.17%, and the final COD reached the national emission standard (<100 mg L−1). At the same time, the results of fluorescence spectrum and gas chromatography–mass spectrometry (GC‐MS) analysis confirmed this point. The stability of the catalyst decreased with the increase in usage times, and the final COD removal efficiency was 73.91% after six cycles of use. To understand the reason for catalyst deactivation, the adsorbed organic matter on the catalyst surface was determined by GC‐MS analysis. In addition, COD removal of the catalyst can be increased to 80.55% after in situ regeneration of the mesh catalyst by a sequential cleaning process consisting of alkali–acid–hydrogen peroxide–ethanol–water.CONCLUSIONIn short, application of the mesh catalyst in catalytic ozonation can be considered as a promising method for wastewater treatment, because of avoidance of solid–liquid separation and easy regeneration of catalytic activity. © 2020 Society of Chemical Industry

Electrochemical Behaviour of High Specific Capacity Spinel LixMn2-YTiyO4 As Cathode Material for Li-Ion Batteries

The demand for high capacity batteries is increasing rapidly with the upcoming energetic needs of an ever-increasing population, especially in the transportation sector. Inexpensive electric vehicles with long range and high durability are also essential for decarbonisation targets. Spinel-type LixMn2O4 cathode materials have been proposed as an alternative to the more expensive LiCoO2 cathode materials for Li-ion batteries. However, the spinel structure distorts when operated below 3.0 V vs. Li|Li+ due to undesired Jahn-Teller effect [1], lowering its stability and precluding its deployment and commercialisation. Adding Ti to replace a ‘y’ amount of Mn in the spinel, i.e. LixMn2-yTiyO4, has been proposed to stabilise the spinel structure below 3.0 V vs. Li|Li+, allowing a specific capacity of 308 mAh g-1 (for y=1) thanks to existence of both Mn4+|Mn3+ and Mn3+|Mn2+ transitions [2]. However, stability issues persist, and specific capacities decrease with the amount of electrochemically inactive Ti. The aim of this work is to optimise the stoichiometry of LixMn2-yTiyO4 by varying the amount of Ti used in a modified sol-gel method [2]; and to study their electrochemical performance by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and charge/discharge cycling with hopes to understand underlying degradation processes during cycling, and propose suitable strategies to diminish their effects on Li-ion batteries. Additionally, cathode materials were characterised by XRD and XPS before and after cycling, along with Raman, SEM and BET surface area.XRD and Raman confirmed a successful synthesis of spinel-type LixMn2-yTiyO4 cathode materials. Traces of TiO2/rutile were observed only in the XRD patterns for stoichiometry y=1 (LiMnTiO4). In all other cases, the shape and intensity of the peaks in the XRD pattern confirmed a correct crystalline structure. SEM showed that nanometric particles (ca. 100 nm) were synthesised in all cases. XPS showed a decrease in the intensity of the Mn 2p and Ti 2p cores lines before and after 20 cycles, possible due to leaching or loss of active material during cycling.The stoichiometry LiMn1.8Ti0.2O4 showed the best initial specific capacity, ca. 215 mAh g-1 as seen in Fig. 1a. A pronounced decrease of the specific capacity during cycling was evident in all cases when the operating potential window was 4.6 – 2.0 V vs. Li|Li+. However, when the potential window was narrowed to 4.6 – 3.0 V vs. Li|Li+, the cathode’s initial specific capacity was halved, although stability improved considerable during 50 cycles. This is a clear indication of undesired structure modifications when the transition Mn3+|Mn2+ occurs, which can be seen the voltammogram in Fig. 1(b) and it is confirmed by EIS spectra, shown in Fig. 1(c), by a considerable increase of the total impedance only after 5 cycles.

Kinetics and Mechanism of Catalytic Oxidation of NO in Coal Combustion Flue Gas over Co-Doped Mn–Ti Oxide Catalyst

The coprecipitation method was used to prepare Mn/Ti, Mn/Co/Ti, and Co/Ti metal oxide catalysts to oxidize NO with O2. The influence of the concentrations of NO and O2 on the oxidation of NO was in...

Spinel-layered Li2MnTiO4+z nanofibers as cathode materials for Li-ion batteries

In this study, we propose composite materials based on the Li–Mn–Ti–O system to develop low cost and environmentally benign cathode materials for Li-ion batteries. Specifically, spinel-layered Li2MnTiO4+z (0.5LiMnTiO4•0.5Li2Mn0·5Ti0·5O3) material is studied with the aim to increase the operating voltage of the cathode. In contrast, to increase the capacity as well as rate capability of the cathode, an electrospinning technique is employed to synthesize uniform nanofibers with diameters of approximately 80 nm and a length of 15 μm. The hetero- and one-dimensional structure of the prepared sample facilitate Li+ transport by shortening the diffusion length for the ions. Consequently, high capacities of 210 (average operating voltage ~3.1 V) and 150 mAh g−1 at C/10 and 1C rates, respectively, are obtained.

Forming the structure and the properties of electric arc coatings based on high manganese steel alloyed with titanium and niobium carbides

The formation of the phase composition, structure, and properties of electric-arc coatings by electrode materials based on high-manganese austenite steel, which is strengthened by twinning steel alloyed by titanium and niobium carbides, was studied. Hardfacing alloys were applied using flux-cored arc welding (FCAW), which consisted of a shell of low-carbon steel filled with a powder mixture containing ferrosilicon manganese, graphite, rutile, fluorite, carbide of niobium or titanium.The phase composition of the coatings was calculated by the CALPHAD method using the Thermo-Calc and Dictra software to simulate equilibrium and non-equilibrium alloy cooling, respectively. The results of calculations show that the cooling conditions at hardfacing lead to the formation of the structure of metastable manganese austenite and minor (0.2 % by weight) amount of carbide of cementite type M3C. This amount of the carbide phase cannot adversely affect the ability of austenite to deformation strengthening. Crystallization of titanium and niobium carbides begins at a high temperature of ~2,400 K and does not affect the phase transformations of austenite into the liquid and solid state. Thus, after cooling, the coating structure mainly consists of two phases, specifically, austenite and niobium or titanium carbide MS in an amount of ~9 vol. %.According to the results from studying the microstructure using scanning electron microscopy and energy-dispersive X-ray spectroscopy of the selected area, the MС carbide phase is released as evenly distributed small particles of the shape that is close to cubic. Carbide particles are mainly located inside austenite grains.Measurement of the hardness of hardfacing coatings shows that at alloying high-manganese austenite steel with niobium and titanium carbides, the hardness significantly increases in hardfacing state from 22 to 35 HRC and after cold plastic deformation from 44 to 52 HRC. The research of wear resistance under conditions of wear by the dry sand – rubber roller pattern shows that TiC and NbC additives can significantly (by 1.6–1.8 times) improve wear resistance of hardfacing coatings.Due to the ability to deformation strengthening in combination with high abrasion resistance, the obtained materials for hardfacing the systems Fe–Mn–Nb–Si–C and Fe–Mn–Ti–Si–C can be recommended for application to working surfaces of digging machines

Interdiffusion and atomic mobility in the bcc Ti–rich Ti–Cr–Mn system

In this work, ternary interdiffusivities in the bcc Ti–rich Ti–Cr–Mn alloys at 1273 K were determined by using the combination of the diffusion couple technique and the Matano–Kirkaldy method. Subsequently, on the basis of the presently obtained interdiffusivities along with the diffusivity and mobility parameters of binary sub–systems within the Ti–Cr–Mn system and thermodynamic descriptions for the bcc Ti–Cr–Mn system, the atomic mobilities of Ti, Cr and Mn in the bcc Ti–Cr–Mn alloys were assessed using the optimization module within the Thermo-Calc software package. Moreover, the comprehensive comparisons between the experimental diffusion properties (i.e., interdiffusivities, composition profiles, and diffusion paths) and the calculated/model–predicted data due to the present atomic mobilities were conducted in order to verify the reliability of the mobilities. At present, the atomic mobilities for the bcc Ti–Cr–Mn system can provide an accurate interdiffusivity matrix over a wide composition range.

High-temperature transport properties of lithium manganese spinels substituted with Ni and Ti

Spinel Li1.05Mn2O4−δ substituted with Ni and Ti were fabricated via a solid-state reaction technique. The Rietveld refinement of synchrotron X-ray powder diffraction data confirmed an Fd3‾m space group of spinel structure for all synthesized materials. Variation in the lattice parameter and M-O distances (M: transition metal at 16d site) due to the dopant content indicated that Ni substitution enhanced the overlap in Mn 3d wave functions and Ti substitution induced structural distortion. Electrical conductivity measurements based on a four-probe method were conducted at high temperatures, demonstrating that both the Ni- and Ti-substituted samples exhibited the same non-adiabatic small-polaron hopping mechanism as that of the non-substituted LiMn2O4. Thermopower measurements were performed at high temperatures via a steady-state technique. All samples with and without substitution were characterized as n-type semiconductors and their Seebeck coefficients were thermally activated. The electrical conductivities and the Seebeck coefficients decreased with increasing Ni content, whereas they were less affected by Ti substitution. The activation energies of electrical conductivity Eσ and thermopower ES were derived from the experimental results and were used to calculate the hopping energies, WH. Ni substitution initially reduced WH but substantially increased WH when Ni ​= ​0.5. In contrast, Ti substitution had a major effect on only ES. Variation in carrier density and structural distortion following the substitution for Mn exerted a large influence on the electrical conductivity and Seebeck coefficients of the doped materials.

New Findings of Rare Minerals in Alkaline Rocks of Ukrainian Shield

Over recent years, new rare minerals have been discovered in the alkaline rocks of the Ukrainian Shield. Agpaitic varieties of alkaline magmatic and metasomatic rocks turned out to be especially abundant in rare minerals. Numerous findings are related to alkaline metasomatites which are considered to be fenites and apofenite albitites of the Dmytrivka quarry. It is well known primarily by the presence of various accessory (Nb, REE, and Zr) minerals, as well as silicate and oxide minerals that are rare for Ukraine. The most common albite microcline fenites of this quarry are characterized by rare-earth mineralization, whereas the concentration of REE decreases in apofenite albitites and Zr and Nb increase. New rare minerals were also found in the essentially albite rock with astrophyllite, alkaline pyroxene and amphibole of the Malatersa massif and agpaitic phonolites of the Oktyabrsky massif. In the rocks of the mentioned massifs and occurrences of alkaline rocks the most interesting are the findings of the perraultite — jinshajiangite series. They were found in three points of the Azov area and include 1) perraultite and jinshajiangite in the alkaline metasomatites of the Dmytrivka quarry; 2) only perraultite in agpaitic phonolites of the Oktyabrsky massif (Kam’yana gully); 3) jinshajiangite in a veined albite rock among the gabbro of the Malatersa massif. Baotite and minerals of the hejtmanite — bafertisite series were also found in the metasomatites of the Dmytrivka quarry. The latter belong to intermediate varieties in terms of MnO (10-17 wt.%) and FeO (10-17 wt.%) which distinguishes them from Fe-rich bafertisite from other regions. A silicate mineral with high content of Na, Zr, Mn and elevated Ti and Nb is rarely observed as small inclusions in the kupletskite grains from alkaline metasomatite of the Dmytrivka quarry. According to the chemical composition it was previously diagnosed as janhaugite. Tainiolite was found in some occurrences of alkaline metasomatites in the Azov region. In addition small aggregates of the REE-enriched epidote were found in fenites of the Kaplany village, which is probably the first finding in Ukraine. Two new Zr minerals have been found in the aegirine syenites of the Korsun-Novomyrhorod pluton: elpidite and mineral with a high content of Y2O3 (13-14 wt.%) (Y-hagatalite ?).

Ab-initio revelation on the origins of Ti substitution for Ga, Mn and Ni on ferromagnetism, phase stability and elastic properties in Ni2MnGa

In the present work, the effects and the underlying mechanisms of Ti substitution for Ga, Mn and Ni on ferromagnetism, phase stability, elastic properties and electronic structures in Ni2MnGa alloy were studied by first-principles calculations. Upon substitution for Ga or Mn, the Ti prefers to directly take the Ga or Mn sites. However, when Ti replaces Ni, the Ti likes to take the site of Mn atom that occupies the Ni site. When Ti replaces Ga, the magnetism is insensitive to the Ti content. On the contrary, when Ti replaces Mn and Ni, both the magnetization and Curie temperature of the alloy are greatly reduced, which are resulted from the reduced Mn content and the indirect occupation manner of Ti, respectively. For the lattice stability, Ti replacement for Ga or Mn (Ni) reduces or enhances the stability of austenite, respectively. Additionally, Ti substitution for Ga could be an effective strategy to tailor c/a ratio of the martensite. As for the elastic properties, we find that Ti substitution for Ga can reduce the intrinsic brittleness of the alloy owing to the decreased p-d hybridization between Ni–Ga. By contrast, the Ti replacement for Ni is harmful to ductility, but can greatly enhance the intrinsic strength of the alloy owing to the coexistence of the p-d bonds between Ni–Ga and Mn–Ga, and the d-d bonds between Ni–Ti and Mn–Ti.

Metal‐Matrix Materials for High‐Temperature Applications with Liquid Aluminum

Herein, powder metallurgically processed transformation‐induced plasticity effect (TRIP)‐steel‐matrix composites with additions of TiO2 or Al2O3–TiO2 are investigated for their potentional use as a impact pad in aluminum melting furnaces. The composites contain volume fractions of 10% or 30% ceramic particles dispersed in a CrMnNi‐steel matrix. The formation of ceramic precipitates in the steel and the interactions between the matrix and the ceramic particles during sintering influence the microstructure of the fired materials. TiO2 promotes the formation of Mn–Ti–O spinel‐type structures whereas the Al2O3–TiO2 material induces the additional formation of Ti–Mn–Al–O solid solutions but reduces the densification progress. Despite material changes, the steel matrix undergoes α'‐martensite formation during quasi‐static tensile loading at room temperature in the reference material and in the composite variants. The yield strength in the composite variant with 10 vol% TiO2 increases by 28% (constant with 10 vol% Al2O3–TiO2), whereby the ultimate tensile strength and the fracture strain are lower for all composite variants as compared to the pure steel. The yield strength of the materials after immersion test in liquid aluminum at 800 °C is +80% (10% TiO2) or +29% (10% Al2O3–TiO2) as compared to the corroded steel material.

Highly efficient, fast and reversible multi-electron reaction of Na3MnTi(PO4)3 cathode for sodium-ion batteries

The sodium super ionic conductor (NASICON) structured Na3MnTi(PO4)3 is attractive due to the eco-friendly and low-cost Na–Mn–Ti–P–O system. However, Na3MnTi(PO4)3 suffers from low Coulombic efficiency, inferior electronic conductivity and limited specific capacity basing on two-sodium-exchange. To address these multifaceted issues, herein, an interpenetrating graphene encapsulated Na3MnTi(PO4)3 particles with carbon-shell covering material (rGO@NMTP-C) was synthesized. By regulating cut-off voltages, a three-electron reaction was realized and Coulombic efficiency of the rGO@NMTP-C was found to increase from <96% to 100% due to the fast kinetics that enhanced by Ti3+/Ti4+ redox, which was verified by EIS and GITT. Sodium storage mechanism of the multielectron reaction was deeply studied by ex-situ XRD and DFT calculations. It shows that the enhanced reversibility synergizing with multifunctional 3D conductive network and the contribution of pseudocapacitance, makes rGO@NMTP-C a promising cathode candidate, which can exhibit a remarkable discharge capacity of 173 mA h g−1. Additionally, for the first time, the rGO@NMTP-C achieves outstanding high rate capability of 92.4 mA h g−1 at 50C, and cycling stability of 74.5% of capacity retention after 3500 cycles at 20C. High performance full cells were also realized for practical utilization of SIBs.

Towards V-based high-entropy alloys for nuclear fusion applications

By mixing elements with favourable nuclear activation properties to create high-entropy alloys, it may be possible to create a material that can withstand a nuclear fusion environment while minimising the radioactive waste produced. Such a material could be used in the extreme thermal and irradiation conditions of a fusion blanket. A suite of previously unexplored V–Cr–Mn and V–Cr–Mn–Ti alloys have been fabricated then homogenised and the resultant microstructures and phases were characterised. Results demonstrate that single-phase body centred cubic solid solution microstructures can be formed in highly-concentrated alloys incorporating low-activation elements, which is promising for a fusion alloy development standpoint.

Synthesis of manganese titanate and its precursors from xerogel

An overview of research on the synthesis of manganese titanates is presented. The xerogel of Mn–Ti–O–C–H composition was synthesized from manganese acetate and titanium tetrabutylate via liquid-phase method using organic solvents. The calcination of xerogel in air at 450 °C and 700 °C yielded manganese titanate precursors in the form of a nanostructured mixture of Mn2O3 and TiO2. Annealing at 1000 °C, manganese metatitanate MnTiO3 was obtained. Reference experiments with initial reagents included, separately, thermal decomposition of Mn(CH3COO)2×4H2O and the product of Ti(OC4H9)4 hydrolysis. The composition, structure, and properties of the products were studied using X-ray diffraction, scanning electron microscopy, elemental analysis, diffuse reflectance IR Fourier spectroscopy, thermogravimetry, and by measuring specific surface area. The data presented by these different techniques are basically consistent with each other (with an increase in the annealing temperature, an increase in globule size and decrease in specific surface area are observed; structuring occurs within the long- and short-range order; the size of the crystallites does not exceed that of the globules; elemental composition correlates with phase composition; the endothermic character of the reaction of MnTiO3 formation at 900 °C is confirmed by a thermodynamic calculation). Nevertheless, some unexpected effects were revealed (based on the FTIR diffuse reflection spectra, mixed oxide Mn–Ti–O is formed in the surface layer of particles already at 450 °C and 700 °C; etc.). Application of the proposed technique for modifying Al2O3 powders, with the aim of implementing low-temperature sintering of corundum ceramics, is discussed.

Giant elastocaloric effect and exceptional mechanical properties in an all-d-metal Ni–Mn–Ti alloy: Experimental and ab-initio studies

Exploring novel materials with superior elastocaloric effect (eCE) is a central issue for the development of eCE refrigeration technique. In this work, we report a giant adiabatic temperature change ΔTad of −20.4 K in the 〈100〉-textured all-d-metal Ni50Mn31.75Ti18.25 bulk alloy. The ΔTad value, comparable to that of the sate-of-the-art Ni–Ti alloys, surpasses the existing conventional Ni–Mn-based alloys. Investigations show that the giant ΔTad is attributed to the large lattice volume change during martensitic transformation and the negligible negative contribution of magnetic entropy change owing to its weak magnetism. By performing X-ray diffraction measurements and ab-initio calculations, the weak magnetism is found to be intrinsically related to the B2 ordered structure in which the magnetic moments of the antiferromagnetically coupled Mn atoms located at 4a and 4b sites are cancelled out each other. Both experimental and theoretical studies confirm that Ni–Mn–Ti alloys possess the significantly enhanced mechanical properties compared with the conventional Ni–Mn-based alloys. Electronic structure investigations reveal that this could be ascribed to the replacement of d-d interaction for the strongly covalent p-d hybridization. Outstanding elastocaloric effect of the all-d-metal alloy opens a door for searching novel promising materials used as the elastocaloric refrigerants.

Probing Nanoscale Phase Separation at Atomic Resolution within β-Type Ti-Mn Alloy: A Potential Candidate for Biomedical Implants.

Biocompatible β-type Ti alloys with high ultimate tensile strength (UTS) and yield strength are potential candidates for certain orthopedic and cardiovascular implants. Aiming for these applications, Ti alloy with 14 wt % Mn (Ti-14 Mn) as β-stabilizer was processed through thermomechanical treatment along with solutionizing and quenching, followed by 95% cold rolling, which resulted in ultrahigh UTS and yield strength. 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolimbromide assay with different cell lines suggests efficient cell growth on alloy surface without compromising biocompatibility. Cell adhesion and spreading assay show that cells are not only able to attach to the alloy surface but also able to spread and grow with normal morphology, which projects this material as a potential candidate for biomedical application. Previous studies on binary β-type Ti alloy systems treated with the above-mentioned processing route confirm the presence of nanoscale phase separation, which enhances its mechanical properties. To discover the same phenomena in the alloy of the present study, bright-field and high-resolution transmission electron microscopy (HRTEM) imaging experiments were performed and nanoscale contrast-modulated lamella regions were observed. Geometrical phase analysis on complex-valued exit wave, reconstructed using focal series HRTEM images, demonstrates that the lamella is a result of d-spacing modulation. Ab initio calculation indicates that d-spacing modulation with the same crystal structure occurs due to composition modulation and was proved by scanning transmission electron microscopy imaging coupled with quantitative energy-dispersive X-ray spectroscopy. Correlating contrast, strain, and composition modulation confirms nanoscale phase separation, which is the first report of this phenomenon in Ti-Mn alloy system.

Trace Element Composition of Igneous and Hydrothermal Magnetite from Porphyry Deposits: Relationship to Deposit Subtypes and Magmatic Affinity

AbstractThe trace element composition of igneous and hydrothermal magnetite from 19 well-studied porphyry Cu ± Au ± Mo, Mo, and W-Mo deposits was measured by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and then classified by partial least squares-discriminant analysis (PLS-DA) to constrain the factors explaining the relationships between the chemical composition of magnetite and the magmatic affinity and porphyry deposit subtypes. Igneous magnetite can be discriminated by relatively high P, Ti, V, Mn, Zr, Nb, Hf, and Ta contents but low Mg, Si, Co, Ni, Ge, Sb, W, and Pb contents, in contrast to hydrothermal magnetite. Compositional differences between igneous and hydrothermal magnetite are mainly controlled by the temperature, oxygen fugacity, cocrystallized sulfides, and element solubility/mobility that significantly affect the partition coefficients between magnetite and melt/fluids. Binary diagrams based on Ti, V, and Cr contents are not enough to discriminate igneous and hydrothermal magnetite in porphyry deposits.Relatively high Si and Al contents discriminate porphyry W-Mo hydrothermal magnetite, probably reflecting the control by high-Si, highly differentiated, granitic intrusions for this deposit type. Relatively high Mg, Mn, Zr, Nb, Sn, and Hf but low Ti and V contents discriminate porphyry Au-Cu hydrothermal magnetite, most likely resulting from a combination of mafic to intermediate intrusion composition, high chlorine in fluids, relatively high oxygen fugacity, and low-temperature conditions. Igneous or hydrothermal magnetite from Cu-Mo, Cu-Au, and Cu-Mo-Au deposits cannot be discriminated from each other, probably due to similar intermediate to felsic intrusion composition, melt/fluid composition, and conditions such as temperature and oxygen fugacity for the formation of these deposits.The magmatic affinity of porphyritic intrusions exerts some control on the chemical composition of igneous and hydrothermal magnetite in porphyry systems. Igneous and hydrothermal magnetite related to alkaline magma is relatively rich in Mg, Mn, Co, Mo, Sn, and high field strength elements (HFSEs), perhaps due to high concentrations of chlorine and fluorine in magma and exsolved fluids, whereas those related to calc-alkaline magma are relatively rich in Ca but depleted in HFSEs, consistent with the high Ca but low HFSE magma composition. Igneous and hydrothermal magnetite related to high-K calc-alkaline magma is relatively rich in Al, Ti, Sc, and Ta, due to a higher temperature of formation or enrichment of these elements in melt/fluids.Partial least squares-discriminant analysis on hydrothermal magnetite compositions from porphyry Cu, iron oxide copper-gold (IOCG), Kiruna-type iron oxide-apatite (IOA), and skarn deposits around the world identify important discriminant elements for these deposit types. Magnetite from porphyry Cu deposits is characterized by relatively high Ti, V, Zn, and Al contents, whereas that from IOCG deposits can be discriminated from other types of magnetite by its relatively high V, Ni, Ti, and Al contents. IOA magnetite is discriminated by higher V, Ti, and Mg but lower Al contents, whereas skarn magnetite can be separated from magnetite from other deposit types by higher Mn, Mg, Ca, and Zn contents. Decreased Ti and V contents in hydrothermal magnetite from porphyry Cu and IOA, to IOCG, and to skarn deposits may be related to decreasing temperature and increasing oxygen fugacity. The relative depletion of Al in IOA magnetite is due to its low magnetite-silicate melt partition coefficient, immobility of Al in fluids, and earlier, higher-temperature magmatic or magmatic-hydrothermal formation of IOA deposits. The relative enrichment of Ni in IOCG magnetite reflects more mafic magmatic composition and less competition with sulfide, whereas elevated Mn, Mg, Ca, and Zn in skarn magnetite results from enrichment of these elements in fluids via more intensive fluid-carbonate rock interaction.

Effects of {332}〈113〉 Deformation Twinning on Fatigue Behavior of Ti–Mn System Alloys

Effects of {332}〈113〉 Deformation Twinning on Fatigue Behavior of Ti–Mn System Alloys

Hydrogenation and dehydrogenation cycle properties of Ti–Mn based alloy Ti0.93Zr0.07Mn1.15Cr0.35 in hydrogen gas

Hydrogenation and dehydrogenation cycle tests at 0 °C for Ti0.93Zr0.07Mn1.15Cr0.35 were carried out 2000 cycles and more in the hydrogen gas with purity of 99.99% and 99.99999%. The capacity maintenance rates at the 2000th cycle for the first cycle were 82% and 97% for each purity hydrogen gas, respectively. It was found that the cycle durability of this alloy depends on the gas purity. By the X-ray diffraction and light element analysis, it was confirmed that the C14 type crystal structure of this alloy was maintained but the nitrogen concentration in the sample with large capacity reduction was increased after the cycle test. The main factor of the decrease in capacity of this alloy is degradation due to reaction with impurity gas components such as nitrogen.

Towards micro- and nanostructured AlZnCu alloys cast from commercial-purity metals

Structural and composition modification of high-zinc aluminum alloys refines their microstructural scale from a few millimeters to a few micrometers. In a series of studies, high-aluminum Al–30Zn alloys were doped with (2–20) wt.% Cu, 1 wt% Mn and small (∼100 ppm) Ti addition. The alloys’ microstructure has been studied using SEM/EBSD (scanning electron microscopy/electron backscatter diffraction) and LM (light microscopy) techniques. A small addition of Ti introduced with Al-3 wt.% Ti-0.15 wt% C (TiCAl) master alloy decreases the grain diameter in the high-aluminum zinc alloys from 1500–2000 μm to 100–200 μm. The high-zinc, high-copper alloy (Al–30Zn–20Cu) cast into a steel mold shows microstructure refinement to 2–5 μm. The observed refinement should improve the ductility of the examined alloys while preserving other properties discussed in the paper.