Fe Zr Research Articles

Role of noble metal fission products on the microstrutural evolution and corrosion behaviour of ferritic steel-Zr based metal waste form alloys in the simulated repository environment

In the present work, the noble metal fission products (NMFPs) alloyed ferritic steel-Zr based metal waste form (MWF) alloys and its influence on microstructure and corrosion behavior in simulated ground water environment was investigated for pyrochemical nuclear spent fuel reprocessing applications. Ingots of 9Cr1Mo steel-12Zr-NMFPs MWF alloy with different NMFP (Ru, Rh and Pd) concentrations (1–4 wt%) were fabricated via vacuum arc melting. Microstructural examination revealed the eutectic layer microstructure consisting of α-Fe and Fe–Zr phases with the preferential distribution of NMFP along with Fe–Zr phases. XRD analysis confirmed that the noble metal does not show any discrete noble metal phases but as intermetallics phases. Electrochemical corrosion studies of the MWF alloys in the simulated Rajasthan Ground Water (RGW) and Kalpakkam Ground Water (KGW) media showed improved corrosion resistance with increase in noble metal content of the alloy due to cathodic modification. Higher noble metal-containing MWF alloys exhibited more protective passive film properties is attributed to the enhancement of Ru, Rh and Pd noble metals in the alloy which influences on the formation of more stable Fe3+ state than unstable Fe2+ state and vice versa with less noble metal-containing MWF alloy confirmed by XPS. Thus, the current investigation addressed the immobilization of noble metals fission product in the alloy microstructure and their beneficial impact on corrosion performance of ferritic steel-Zr based MWF alloy which are of primary concern in the high-level radioactive waste disposal in a geological repository.

Corrosion property and biocompatibility evaluation of Fe–Zr–Nb thin film metallic glasses

The biocompatible thin film metallic glass (TFMGs) materials can be used to modify the substrate material due to their good corrosion resistance and adequate biocompatibility. In this work, five Fe–Zr–Nb TFMGs were fabricated on Si wafer and AISI420 stainless steel disk substrates using three pure targets co-sputtering system. The niobium target power was adjusted to grow TFMGs with different Nb contents ranging from 21.7 to 26.7 at%. Very fine and dense featureless microstructure was discovered for each Fe–Zr–Nb TFMG. The hardness, elastic modulus, H/E and H3/E2 ratios of Fe–Zr–Nb TFMG increased with increasing Nb content. Good adhesion property was revealed for each TFMG. The corrosion resistance of the bare AISI420 stainless steel disk was greatly improved by the deposited Fe–Zr–Nb TFMG. Very good biocompatibility and MG63 cell viability were also found for TFMGs implying their potential application as biomedical materials.

Production of Permanent Magnets for Magnetically Hard Alloys Using Rare-Earth Metals

A requirement for improving powder metallurgy technology of alloys for permanent magnets containing rare-earth metals based on the use of secondary resources and a replacement of rare-earth metals and fine control of the semifinished products chemical composition is demonstrated. These approaches are realized successfully in the preparation of Nd–Fe–B system magnetically hard materials by a binary mixture method using rare earth metal hydrides and their alloys. Analysis of the magnetic properties of Sm–Co–Cu–Fe–Zr system permanent magnets according to the results of the primary ingot chemical composition control minimizes production costs.

Microstructure and corrosion behaviour of ferritic steel–Zr-based metal waste form alloys in simulated ground water

ABSTRACTThe microstructure and corrosion behaviour of the metal waste form (MWF) alloys based on ferritic steel with Zr content in the range of 3–15 wt-% were investigated. The MWF alloys are composed of α-Fe and Fe-Zr phases and with the increase of Zr content, α-Fe phase gradually decreases and the relative content of Fe–Zr intermetallic phase also increases. TEM and XRD confirmed the presence of Fe2Zr and Fe23Zr6 intermetallics. Potentiodynamic polarisation curves showed The MWF alloys exhibited passivation behaviour in the simulated Kalpakkam (KGW) and Rajasthan ground water (RGW) media. Electrochemical impedance spectra revealed improved passive film stability in RGW than in KGW which is related to the formation of more stable adherent insoluble passive film in RGW. Higher Zr containing MWF alloy exhibited higher corrosion resistance than lower Zr containing MWF alloys. The relative content of Fe–Zr intermetallics is attributed for the corrosion resistance of The MWF alloys.

Heat capacity measurement of Zr2Fe and thermodynamic re-assessment of the Fe–Zr system

Critical evaluation of the Fe–Zr binary system has been performed based on the available experimental and calculated data. New experimental data on the heat capacity of Zr2Fe have been obtained using differential scanning calorimetry. Thermodynamic parameters have been optimized using the CALPHAD approach. New experimental results of specific heat capacity and ab-initio calculations for the ZrFe2, Zr2Fe and Zr3Fe intermetallic compounds have been taken into account in the optimization of the thermodynamic parameters. A self-consistent thermodynamic description of the Fe–Zr system has been obtained. Using the generalized “χ2”–criterion, the results calculated using the thermodynamic descriptions derived in the present work are compared with those previously published.

Zirconium Doped Precipitated Fe-Based Catalyst for Fischer–Tropsch Synthesis to Light Olefins at Industrially Relevant Conditions

Direct conversion of synthesis gas to light olefins (ethylene, propylene, and butylenes) over Fe–Zr co-precipitated catalysts was investigated in a continuous-flow fixed-bed reactor at industrially relevant conditions. The effect of incorporation of zirconium on the textural properties, surface physicochemical properties, and reduction/carburization ability of Fe-based multi-component catalysts were examined by N2 adsorption–desorption, X-ray diffraction, transmission electron microscope, H2 temperature-programmed reduction (H2-TPR), CO temperature-programmed reduction, and X-ray photoelectron spectroscopy. The results indicated that the addition of less zirconium can promote the dispersion of iron oxide particles and increase the specific surface area of catalyst, leads to a higher Fischer–Tropsch synthesis activity. However, excessive addition of the zirconium promoter will cover the surface active sites and suppress the reduction and carburization of catalyst, which lead to lower activity. Meanwhile, the catalytic stability was destroyed by the addition of less Zr. The charge transfer between Fe and other promoter was redistributed by Zr, which disturbed the original Fe–Mg interaction. When the content of Zr further increased, the stability was improved again by a new formed Fe–Zr interaction. The zirconium promoter can effectively inhibit the chain growth probability and hydrogenation ability, resulting in the improvement of light olefins selectivity.

Magnetic behavior of amorphous Fe–Zr thin films sputtered at different Ar pressures

Abstract Amorphous Fe–Zr thin films with similar compositions exhibit a considerable change in their magnetic behaviors when they are sputtered at different Ar pressures. The change is well explained by a parameter – the SPM ratio – devised in this study, which is defined as the ratio of the magnetization due to the superparamagnetic behavior to the saturation magnetization. The change in the magnetic behavior of thin films with 40–70 at.% Fe depends on an increase in the SPM ratio, and it is more prominent at higher Fe contents; for example, the SPM ratio of a thin film with ∼60 at.% Fe increases from ∼0 to 0.69 with increasing Ar pressure from 2 to 10 mTorr. Subsequent annealing of the thin film fabricated at the Ar pressure of 10 mTorr at 150 °C leads to a 10-fold decrease in its SPM ratio from that in the as-deposited state. This decreased SPM ratio is, nevertheless, still higher than that of the thin film fabricated at the Ar pressure of 2 mTorr. These results indicate that the magnetic behaviors of amorphous Fe–Zr thin films are highly sensitive to the Ar pressure. Thus, it is crucial to take this parameter into account in the analysis of the magnetic behaviors of amorphous Fe–Zr thin films.

Investigation of Particles and Gas Bubbles in Zr⁻0.8Sn⁻1Nb⁻0.3Fe Zr Alloys Irradiated by Krypton Ions.

Two types of Zr–0.8Sn–1Nb–0.3Fe Zr alloys were irradiated by krypton ions in the temperature range from 320 to 400 °C. The microstructure of the as-received alloys showed that the sizes of Zr crystals and (Zr, Nb)2Fe particles with face-centered cubic (FCC) structure increased from 3.9 μm to 6.0 μm and from 74.6 nm to 89.6 nm, respectively, after cold rolling and subsequent annealing. Kr+ irradiation-induced bubble formation in the Zr matrix was observed. The size of the gas bubbles increased with increasing ion fluence and irradiation temperature. An equation that related the bubble size, ion fluence, and temperature were established. Irradiation-induced amorphization of particles was observed and found to be related to the fabrication process and irradiation parameters. The particles in alloy #1 showed a higher irradiation tolerance than those in alloy #2. The threshold damage dose for the amorphization of particles in alloy #2 was 3.5 dpa at 320 °C and 4.9 dpa at 360 °C. The mechanisms for bubble growth and particle amorphization are also discussed.

Promotion effects of Ce added Fe–Zr–K on CO2 hydrogenation to light olefins

Microspherical and uniform Fe–Zr–Ce–K catalysts were prepared by the microwave assisted precipitation followed by impregnation and promoted CO2 hydrogenation toward advantageous synthesis of light olefins. The reducibility, surface basicity and surface atom composition of the catalysts was tuned as the Ce content was varied. The ceria spacer restrained the growth of the Fe2O3 crystallite. Ce addition weakened the interaction between Fe species and zirconia and the reduction of the Fe species became easier. On 35Fe–7Zr–1Ce–K at 320 °C and 2 MPa, the conversion of CO2 and the selectivity of C2–C4 olefins were 57.34 and 55.67%, respectively. The ratio of olefin/paraffin was 7. The selectivity of CO and C5+ hydrocarbons were 3 and 15.87%, respectively. The enhanced performance is attributed to intensified bifunctional activity toward CO hydrogenation as well as the reverse water–gas shift reaction.

One-Pot Synthesis of 2,5-Furandicarboxylic Acid from Fructose in Ionic Liquids

2,5-Furandicarboxylic acid (FDCA), which is usually produced from HMF catalyzed by noble metal catalysts, is an important biobased monomer for the degradable polymer polyethylene furandicarboxylate (PEF). In order to reduce the high costs of starting material and catalysts, a novel approach for the direct conversion of fructose into FDCA was developed by employing [Bmim]Cl as a solvent with non-noble metal (Fe–Zr–O) as a catalyst. Relatively high FDCA yield was obtained at full fructose conversion under optimal conditions. The kinetic study revealed that the oxidation of intermediate FFCA to FDCA possessed the highest activation energy, indicating this step is most affected by reaction temperature. Additionally, in the IL-promoted reaction system, other biomass sources, such as glucose, galactose, mannose, starch, and cellulose also can be directly converted, with lower FDCA yield compared with that of fructose due to the ineffective isomerization of aldohexoses into fructose.

Effect of Si on the Glass Formation and Magnetic Properties of High-Iron Fe–Zr–Si Alloys

High-iron Fe–Zr–Si amorphous ribbons were fabricated through the melt-spun technique. Then, the effects of Si content on the glass-forming ability and magnetic properties of Fe90−xZr10Six (x = 1, 2, 3, 4, 5, 10) alloys were investigated. Results showed that the amorphous structure only formed in an alloy composition of 3 at.% Si. Moreover, α-Fe(Si) and Fe3Zr phase appeared gradually when Si was added. Fe87Zr10Si3 alloy is a unique amorphous structure in Fe90−xZr10Six ribbons. The peak temperatures of the two crystallization stages were 464 and 600 ∘C. The saturation magnetization (Ms) values of the alloys ranged from 91.2 to 132.3 emu/g, and all had an initial increase before decreasing and their coercivity (Hc) values increased with increased Si content. The Fe87Zr10Si3 amorphous alloy exhibited a low Hc value of approximately 39.1 A/m, which shows good magnetic properties in the as-quenched state. After annealing, the Ms of the amorphous sample considerably improved, particularly reaching 165.3 emu/g at 600 ∘C.

Fe–Zr–O catalyzed base-free aerobic oxidation of 5-HMF to 2,5-FDCA as a bio-based polyester monomer

An environment-friendly and economical route for 5-hydroxymethylfurfural (HMF) aerobic oxidation to 2,5-furandicarboxylic acid (FDCA) in an ionic liquid (IL)-promoted base-free reaction system was reported using Fe–Zr–O as a catalyst.

Spectroscopic Study of the Role of Metal Ions in the Adsorption Process of Phosphate in Nanoscaled Adsorbers Based on Metal (Zn/Fe/Zr) Oxyhydroxides

Currently great effort is made to find materials and technologies for the recycling of phosphate from wastewater. Herein, we present an in-depth study of the phosphate adsorption mechanism of a promising adsorber material, a Zn–Fe–Zr oxyhydroxide-based nanostructured precipitate. The behavior of the multicomponent nanomaterial, consisting of both crystalline and amorphous parts, is investigated via X-ray absorption fine structure spectroscopy and Mossbauer spectroscopy, revealing the importance of the nanostructured composition for the phosphate adsorption. We found evidence that adsorption takes place especially in the vicinity of iron sites in the amorphous part of the material.

Thermodynamic description of hydrogen storage materials Cr–Ti–Zr and Fe–Ti–Zr

Abstract

Mechanical and Electrical Properties of Al–Fe–Cr and Al–Fe–Zr Alloys

Mechanical and Electrical Properties of Al–Fe–Cr and Al–Fe–Zr Alloys

Synthesis of dimethyl carbonate from methanol and CO2 over Fe–Zr mixed oxides

A series of Fe–Zr mixed oxides with different Fe content were prepared and used for direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol. The best catalytic performance was achieved over the Fe0.7Zr0.3Oy catalyst, with DMC yield of 0.44 mmol·gcat−1 and DMC selectivity of 100% under the reaction conditions of 110°C and 12MPa. Characterization results of N2 physisorption, XRD, XPS, TPR and NH3/CO2-TPD indicated that the Fe–Zr mixed oxides with coexistence structure of hexagonal Fe2O3 and cubic Fe2O3 favored the formation of moderately acidic and basic sites, which then improved the activation of CO2 and methanol. The DMC yield was shown to be linearly related to the amount of moderately acidic and basic sites.

Thermodynamic Properties of Iron Melts with Titanium, Zirconium, and Hafnium

The literature data on the enthalpies of mixing and thermodynamic activities of Fe–Ti, Fe–Zr, and Fe–Hf liquid alloys are summarized. It is shown that the thermodynamic properties of these systems are characterized by significant negative deviations from the ideal behavior. In the framework of the associated solution model, the composition and temperature dependences of the thermodynamic functions of mixing for the Fe–Ti, Fe–Zr, and Fe–Hf systems are described. The temperature dependence of the thermodynamic properties of the considered systems is characterized by increase in negative deviations from the ideality with decreasing temperature and increasing thermodynamic stability of supercooled melts. Analysis of the degree of short-range order in the system melts, estimated as the total mole fraction of associates Σxass at the glass transition temperature, allows us to successfully interpret the known composition ranges of glass transition for the Fe–Zr and Fe–Hf melts and predict the composition range of glass transition for the Fe–Ti melts.

Influence of a high magnetic field on the solidification structures of ternary Al–Fe–Zr alloy

Abstract

Large variation of magnetic properties of amorphous Fe\u2013Zr thin films with Ar pressure during sputtering

A large change is observed in the magnetic properties of amorphous Fe–Zr thin films sputtered at different Ar pressures. The change depends on the composition of the alloys and at compositions near 60 at.% Fe, for example, the magnetisation measured at 10 kOe increases 30-fold with an increase in the Ar pressure from 2 to 10 mTorr. The magnetic properties are well explained by a combination of two phenomena—superparamagnetism and spin glass behaviours—and the large change is partly related to the number density of a magnetically correlated region. Examinations of the microstructure by X-ray diffraction, transmission electron microscopy, and X-ray absorption fine structure spectroscopy reveal no appreciable difference in it as a function of the Ar pressure. This indicates that even a very slight change in the microstructure can greatly affect the magnetic properties of amorphous Fe–Zr thin films, thereby opening up the possibility of employing the magnetic properties of amorphous alloys for the characterisation of amorphous microstructures.

Теоретична аналіза процесів фазоутворення в аморфних стопах системи Fe—Zr

Теоретична аналіза процесів фазоутворення в аморфних стопах системи Fe—Zr