The Reduction of Cr(VI) to Cr(III) by Natural Fe-Bearing Minerals: A Synchrotron XAS Study

Science.gov (United States)

Xu, H.; Guo, X.; Ding, M.; Migdissov, A. A.; Boukhalfa, H.; Sun, C.; Roback, R. C.; Reimus, P. W.; Katzman, D.

2017-12-01

Cr(VI) in the form of CrO42- is a pollutant species in groundwater and soils that can pose health and environmental problems. Cr(VI) associated with use as a corrosion inhibitor at a power plant from 1956-1972 is present in a deep groundwater aquifer at Los Alamos National Laboratory. A potential remediation strategy for the Cr contamination is reduction of Cr(VI) to Cr(III) via the acceptance of electrons from naturally occurring or induced Fe(II) occurring in Fe-bearing minerals. In this work, using synchrotron-based X-ray techniques, we investigated the Cr reduction behavior by Fe-bearing minerals from outcrop and core samples representative of the contaminated portion of the aquifer. Samples were exposed to solutions with a range of known Cr (VI) concentrations. XANES and EXAFS spectra showed that all the Cr(VI) had been reduced to Cr(III), and micro XRF mapping revealed close correlation of Cr and Fe distribution, implying that Fe(II) in minerals reduced Cr(VI) in the solution. Similar behavior was observed from in-situ XANES measurements on Cr reduction and adsorption by mineral separates from the rock samples in Cr(VI)-bearing solutions. In addition, to obtain reference parameters for interpreting the data of natural samples, we collected Cr and Fe EXAFS spectra of Cr(III)-Fe(III) hydroxide solid solutions, which show progressive changes in the local structure around Cr and Fe over the whole series.

Study of the oxidation of Fe-Cr alloys at high temperatures

International Nuclear Information System (INIS)

Carneiro, J.F.; Sabioni, A.C.S.

2010-01-01

The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1μg. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10 -9 g 2 .cm -4 .s -1 , for the alloy Fe-1.5% Cr, to 1.18 x 10-14g 2 .cm -4 .s -1 for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

Amorphization of C-implanted Fe(Cr) alloys

International Nuclear Information System (INIS)

Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

1991-01-01

The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

International Nuclear Information System (INIS)

Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

2008-01-01

The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

Energy Technology Data Exchange (ETDEWEB)

Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

2002-01-16

An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

Effects of V and Cr on Laser Cladded Fe-Based Coatings

Directory of Open Access Journals (Sweden)

Haiyang Wang

2018-03-01

Full Text Available Fe-based coatings with high V and Cr content were obtained by laser cladding using Fe-based powder with different Cr3C2 and FeV50 content. The results showed that Fe-based coatings were uniform and dense. The constituent phases were mainly composed of α-Fe solid solution with the increase of Cr3C2 and FeV50, γ-Fe and V8C7 phases were achieved. The microstructure of the coatings exhibited a typical dendrite structure. The concentration of C, V and Cr were saturated in dendritic areas, and the other alloying elements were mainly dissolved in the interdendritic areas. The hardness and wear resistance of Fe-based coatings were enhanced with the Cr3C2 and FeV50 addition. The specimen with 15% Cr3C2 and 16% FeV50 had the highest hardness of 66.1 ± 0.6 HRC, which was 1.05 times higher than the sample with 4.5% Cr3C2 and 5% FeV50, and the wear resistance of the former was three times greater than the latter.

Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

International Nuclear Information System (INIS)

Auger, M.A.; Leguey, T.; Munoz, A.; Monge, M.A.; Castro, V. de; Fernandez, P.; Garces, G.; Pareja, R.

2011-01-01

Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y 2 O 3 alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y 2 O 3 developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y 2 O 3 free alloy. Strengthening induced by the Y 2 O 3 dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

Science.gov (United States)

Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

2017-06-01

Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

Ion irradiation effects on high purity bcc Fe and model FeCr alloys

International Nuclear Information System (INIS)

Bhattacharya, Arunodaya

2014-01-01

FeCr binary alloys are a simple representative of the reduced activation ferritic/martensitic (F-M) steels, which are currently the most promising candidates as structural materials for the sodium cooled fast reactors (SFR) and future fusion systems. However, the impact of Cr on the evolution of the irradiated microstructure in these materials is not well understood in these materials. Moreover, particularly for fusion applications, the radiation damage scenario is expected to be complicated further by the presence of large quantities of He produced by the nuclear transmutation (∼ 10 appm He/dpa). Within this context, an elaborate ion irradiation study was performed at 500 C on a wide variety of high purity FeCr alloys (with Cr content ranging from ∼ 3 wt.% to 14 wt.%) and a bcc Fe, to probe in detail the influence of Cr and He on the evolution of microstructure. The irradiations were performed using Fe self-ions, in single beam mode and in dual beam mode (damage by Fe ions and co-implantation of He), to separate ballistic damage effect from the impact of simultaneous He injection. Three different dose ranges were studied: high dose (157 dpa, 17 appm He/dpa for the dual beam case), intermediate dose (45 dpa, 57 appm He/dpa for dual beam case) and in-situ low dose (0.33 dpa, 3030 appm He/dpa for the dual beam case). The experiments were performed at the JANNuS triple beam facility and dual beam in situ irradiation facility at CEA-Saclay and CSNSM, Orsay respectively. The microstructure was principally characterized by conventional TEM, APT and EDS in STEM mode. The main results are as follows: 1) A comparison of the cavity microstructure in high dose irradiated Fe revealed strong swelling reduction by the addition of He. It was achieved by a drastic reduction in cavity sizes and an increased number density. This behaviour was observed all along the damage depth, up to the damage peak. 2) Cavity microstructure was also studied in the dual beam high dose

Magnetism of CrO overlayers on Fe(001)bcc surface: first principles calculations

Science.gov (United States)

Félix-Medina, Raúl Enrique; Leyva-Lucero, Manuel Andrés; Meza-Aguilar, Salvador; Demangeat, Claude

2018-04-01

Riva et al. [Surf. Sci. 621, 55 (2014)] as well as Calloni et al. [J. Phys.: Condens. Matter 26, 445001 (2014)] have studied the oxydation of Cr films deposited on Fe(001)bcc through low-energy electron diffraction, Auger electron spectroscopy and scanning tunneling microscopy. In the present work we perform a density functional approach within Quantum Expresso code in order to study structural and magnetic properties of CrO overlayers on Fe(001)bcc. The calculations are performed using DFT+U. The investigated systems include O/Cr/Fe(001)bcc, Cr/O/Fe(001)bcc, Cr0.25O0.75/Fe(001)bcc, as well as the O coverage Ox/Cr/Fe(001)bcc (x = 0.25; 0.50). We have found that the ordered CrO overlayer presents an antiferromagnetic coupling between Cr and Fe atoms. The O atoms are located closer to the Fe atoms of the surface than the Cr atoms. The ground state of the systems O/Cr/Fe(001)bcc and Cr/O/Fe(001)bcc corresponds to the O/Cr/Fe(001)bcc system with a magnetic coupling c(2 × 2). The effect of the O monolayer on Cr/Fe(001)bcc changes the ground state from p(1 × 1) ↓ to c(2 × 2) and produces an enhancement of the magnetic moments. The Ox overlayer on Cr/Fe(001)bcc produces an enhancement of the Cr magnetic moments.

Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

International Nuclear Information System (INIS)

Garner, F.A.; Brager, H.R.

1986-06-01

Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

Energy Technology Data Exchange (ETDEWEB)

Auger, M.A., E-mail: mauger@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Leguey, T., E-mail: leguey@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Munoz, A., E-mail: amunoz@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Castro, V. de, E-mail: vanessa.decastro@materials.ox.ac.uk [Department of Materials, University of Oxford, OX1 3PH (United Kingdom); Fernandez, P., E-mail: pilar.fernandez@ciemat.es [National Fusion Laboratory-CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Garces, G., E-mail: ggarces@cenim.csic.es [Departamento de Metalurgia Fisica, CENIM (CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Pareja, R., E-mail: rpp@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain)

2011-10-01

Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y{sub 2}O{sub 3} alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y{sub 2}O{sub 3} developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y{sub 2}O{sub 3} free alloy. Strengthening induced by the Y{sub 2}O{sub 3} dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

Molecular dynamics study on threshold displacement energies in Fe-Cr alloys

Science.gov (United States)

Fu, Jiawei; Ding, Wenyi; Zheng, Mingjie; Mao, Xiaodong

2018-03-01

The threshold displacement energies (Ed) of Fe and Cr atoms in Fe-Cr alloys with Cr contents ranging from 0% to 21% have been obtained with molecular dynamics (MD) method. The values of Ed have been calculated along the three high-symmetry crystallographic directions [0 0 1], [0 1 1] and [1 1 1], a slightly 2° tilt from these directions, and a high-index crystallographic directions [1 3 5]. The results showed that [0 1 1] crystallographic direction had the highest Ed among the three high-symmetry directions in each Cr content alloy. Fe-9Cr had higher weighted average Ed than the other Cr content alloys for both Fe and Cr PKA due to its statistically high Ed along the [0 1 1] crystallographic direction up to 44.3 eV. And the statistical analysis on the primary damage configuration demonstrated that 〈1 1 0〉Fe-Fe dumbbells were the dominant defect structures after relaxation. These data can enrich the database of Ed in Fe-Cr alloys and have potential applications in guiding the optimization design of radiation-resistant RAFM steels.

Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

Science.gov (United States)

McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

2017-08-01

Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-18

FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO₂ or ZrO₂. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys; Influencia de um revestimento de niobio sobre a resistencia a sulfetacao das ligas FeCr e FeCrY

Energy Technology Data Exchange (ETDEWEB)

Geribola, Gulherme Altomari

2014-07-01

Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H{sub 2}/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

FP corrosion dependence on carbon and chromium content in Fe-Cr steel

International Nuclear Information System (INIS)

Sasaki, Koei; Tanigaki, Takanori; Fukumoto, Ken-ichi; Uno, Masayoshi

2015-01-01

In an attempt to investigate Cs or Cs-Te corrosion dependence on chromium or carbon content in Fe-Cr steel, cesium and Cs-Te corrosion test were performed to three specimens, Fe-9Cr-0C, Fe-9Cr-0.14C and Fe-13Cr-0.14C, for 100 hours at 973K in simulated high burn-up fuel pin environment. Cesium corrosion depth has no dependence on chromium or carbon content in Fe-Cr steel. Cs-Te corrosion was appeared in only Fe-13Cr-0.14C which has chromium carbides ranged along grain boundary. Appearance of the Cs-Te corrosion was determined by distribution or arrangement of chromium carbides which depends on chromium and carbon content. (author)

58Fe AND 54Cr IN EARLY SOLAR SYSTEM MATERIALS

International Nuclear Information System (INIS)

Wang, Kun; Moynier, Frederic; Podosek, Frank; Foriel, Julien

2011-01-01

Stepwise dissolution of primitive meteorites exhibits large 54 Cr anomalies but no collateral effects on 58 Fe and 48 Ca, two other neutron-rich nuclides from the iron peak. These results suggest that 54 Cr must have been produced in particular zones of the rare Type Ia supernovae or that 48 Ca and/or 58 Fe were produced together in Type II supernovae and were chemically separated into some mineral phase that favors Cr over Ca and Fe, and it is the dissolution properties of that phase that is driving the isotopic effect in leaching. The recent findings of nanometer-size oxide grains with very large 54 Cr excesses favored the latter scenario for the origin of the mono-isotopic Cr isotopic effect. In addition, the absence of isotopic variations in the 58 Fe/ 54 Fe ratio at the mineral scale confirms that the short-lived nuclide 60 Fe (T 1/2 = 2.62 Myr) was homogeneously distributed to a less than 15% dispersion in the early solar nebula.

58Fe and 54Cr in Early Solar System Materials

Science.gov (United States)

Wang, Kun; Moynier, Frederic; Podosek, Frank; Foriel, Julien

2011-10-01

Stepwise dissolution of primitive meteorites exhibits large 54Cr anomalies but no collateral effects on 58Fe and 48Ca, two other neutron-rich nuclides from the iron peak. These results suggest that 54Cr must have been produced in particular zones of the rare Type Ia supernovae or that 48Ca and/or 58Fe were produced together in Type II supernovae and were chemically separated into some mineral phase that favors Cr over Ca and Fe, and it is the dissolution properties of that phase that is driving the isotopic effect in leaching. The recent findings of nanometer-size oxide grains with very large 54Cr excesses favored the latter scenario for the origin of the mono-isotopic Cr isotopic effect. In addition, the absence of isotopic variations in the 58Fe/54Fe ratio at the mineral scale confirms that the short-lived nuclide 60Fe (T 1/2 = 2.62 Myr) was homogeneously distributed to a less than 15% dispersion in the early solar nebula.

Negative impact of oxygen molecular activation on Cr(VI) removal with core–shell Fe@Fe2O3 nanowires

International Nuclear Information System (INIS)

Mu, Yi; Wu, Hao; Ai, Zhihui

2015-01-01

Highlights: • The presence of oxygen inhibited Cr(VI) removal efficiency with nZVI by near 3 times. • Cr(VI) removal with nZVI was related to adsorption, reduction, co-precipitation, and adsorption reactions. • Molecular oxygen activation competed donor electrons from Fe 0 core and surface bound Fe(II) of nZVI. • Thicker Cr(III)/Fe(III)/Cr(VI) oxyhydroxides shell of nZVI leaded to the electron transfer inhibition. - Abstract: In this study, we demonstrate that the presence of oxygen molecule can inhibit Cr(VI) removal with core–shell Fe@Fe 2 O 3 nanowires at neutral pH of 6.1. 100% of Cr(VI) removal was achieved by the Fe@Fe 2 O 3 nanowires within 60 min in the anoxic condition, in contrast, only 81.2% of Cr(VI) was sequestrated in the oxic condition. Removal kinetics analysis indicated that the presence of oxygen could inhibit the Cr(VI) removal efficiency by near 3 times. XRD, SEM, and XPS analysis revealed that either the anoxic or oxic Cr(VI) removal was involved with adsorption, reduction, co-precipitation, and re-adsorption processes. More Cr(VI) was bound in a reduced state of Cr(III) in the anoxic process, while a thicker Cr(III)/Fe(III)/Cr(VI) oxyhydroxides shell, leading to inhibiting the electron transfer, was found under the oxic process. The negative impact of oxygen molecule was attributed to the oxygen molecular activation which competed with Cr(VI) adsorbed for the consumption of donor electrons from Fe 0 core and ferrous ions bound on the iron oxides surface under the oxic condition. This study sheds light on the understanding of the fate and transport of Cr(VI) in oxic and anoxic environment, as well provides helpful guide for optimizing Cr(VI) removal conditions in real applications

Development of low-Cr ODS FeCrAl alloys for accident-tolerant fuel cladding

Science.gov (United States)

Dryepondt, Sebastien; Unocic, Kinga A.; Hoelzer, David T.; Massey, Caleb P.; Pint, Bruce A.

2018-04-01

Low-Cr oxide dispersion strengthened (ODS) FeCrAl alloys were developed as accident tolerant fuel cladding because of their excellent oxidation resistance at very high temperature, high strength and improved radiation tolerance. Fe-12Cr-5Al wt.% gas atomized powder was ball milled with Y2O3+FeO, Y2O3+ZrO2 or Y2O3+TiO2, and the resulting powders were extruded at 950 °C. The resulting fine grain structure, particularly for the Ti and Zr containing alloys, led to very high strength but limited ductility. Comparison with variants of commercial PM2000 (Fe-20Cr-5Al) highlighted the significant impact of the powder consolidation step on the alloy grain size and, therefore, on the alloy mechanical properties at T < 500 °C. These low-Cr compositions exhibited good oxidation resistance at 1400 °C in air and steam for 4 h but could not form a protective alumina scale at 1450 °C, similar to observations for fine grained PM2000 alloys. The effect of alloy grain size, Zr and Ti additions, and impurities on the alloy mechanical and oxidation behaviors are discussed.

Development of an EAM potential for simulation of radiation damage in Fe-Cr alloys

International Nuclear Information System (INIS)

Wallenius, J.; Abrikosov, I.A.; Chakarova, R.; Lagerstedt, C.; Malerba, L.; Olsson, P.; Pontikis, V.; Sandberg, N.; Terentyev, D.

2004-01-01

We have developed a set of EAM potentials for simulation of Fe-Cr alloys. By relaxing the requirement of reproducing the pressure-volume relation at short distances and by fitting to the thermal expansion coefficients of Fe and Cr, stability of the self-interstitial could be obtained. For Cr, properties of the paramagnetic state were applied, providing a positive Cauchy pressure. Mixed Fe-Cr pair potentials were fitted to the calculated mixing enthalpy of ferromagnetic Fe-Cr. Simulation of thermal ageing in Fe-Cr alloys using the Fe-20Cr potential exhibited pronounced Cr-precipitation for temperatures below 900 K, a feature not observed at any temperature using a potential fitted to the mixing enthalpy of Fe-5Cr

Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

International Nuclear Information System (INIS)

Lee, Kee Ahn; Kim, Yong Chan; Kim, Jung Han; Lee, Chong Soo; Namkung, Jung; Kim, Moon Chul

2007-01-01

The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys

Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

Energy Technology Data Exchange (ETDEWEB)

Lee, Kee Ahn [School of Advanced Materials Engineering, Andong National University, Andong 760-749 (Korea, Republic of)]. E-mail: keeahn@andong.ac.kr; Kim, Yong Chan [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Jung Han [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Lee, Chong Soo [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Namkung, Jung [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Moon Chul [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of)

2007-03-25

The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys.

Cr(VI) retention and transport through Fe(III)-coated natural zeolite

Energy Technology Data Exchange (ETDEWEB)

Du, Gaoxiang [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Li, Zhaohui, E-mail: li@uwp.edu [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144 (United States); Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Libing [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Hanson, Renee; Leick, Samantha; Hoeppner, Nicole [Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

2012-06-30

Graphical abstract: Breakthrough curves of Cr(VI) from columns packed with raw zeolite (a) and Fe(III)-zeolite (b). The solid line in (b) is the HYDRUS-1D fit to the observed data with adsorption term only, while the dashed line in (b) includes a reduction term in the HYDRUS-1D fit. Highlights: Black-Right-Pointing-Pointer Zeolite modified with Fe(III) could be used for adsorption and retention of Cr(VI). Black-Right-Pointing-Pointer The Fe present on zeolite was in an amorphous Fe(OH){sub 3} form. Black-Right-Pointing-Pointer A Cr(VI) adsorption capacity of 82 mg/kg was found on Fe(III)-zeolite. Black-Right-Pointing-Pointer A Cr(VI) retardation factor of 3 or 5 was determined from column and batch studies. - Abstract: Cr(VI) is a group A chemical based on the weight of evidence of carcinogenicity. Its transport and retention in soils and groundwater have been studied extensively. Zeolite is a major component in deposits originated from volcanic ash and tuff after alteration. In this study, zeolite aggregates with the particle size of 1.4-2.4 mm were preloaded with Fe(III). The influence of present Fe(III) on Cr(VI) retention by and transport through zeolite was studied under batch and column experiments. The added Fe(III) resulted in an enhanced Cr(VI) retention by the zeolite with a capacity of 82 mg/kg. The Cr(VI) adsorption on Fe(III)-zeolite followed a pseudo-second order kinetically and the Freundlich adsorption isotherm thermodynamically. Fitting the column experimental data to HYDRUS-1D resulted in a retardation factor of 3 in comparison to 5 calculated from batch tests at an initial Cr(VI) concentration of 3 mg/L. The results from this study showed that enhanced adsorption and retention of Cr(VI) may happen in soils derived from volcanic ash and tuff that contains significant amounts of zeolite with extensive Fe(III) coating.

Determination of the Fe-Cr-Ni and Fe-Cr-Mo Phase Diagrams at Intermediate Temperatures using a Novel Dual-Anneal Diffusion-Multiple Approach

Science.gov (United States)

Cao, Siwei

Phase diagrams at intermediate temperatures are critical both for alloy design and for improving the reliability of thermodynamic databases. There is a significant shortage of experimental data for phase diagrams at the intermediate temperatures which are defined as around half of the homologous melting point (in Kelvin). The goal of this study is to test a novel dual-anneal diffusion multiple (DADM) methodology for efficient determination of intermediate temperature phase diagrams using both the Fe-Cr-Ni and Fe-Cr-Mo systems as the test beds since both are very useful for steel development. Four Fe-Cr-Ni-Mo-Co diffusion multiples were made and annealed at 1200 °C for 500 hrs. One sample was used directly for evaluating the isothermal sections at 1200 ° C. The other samples (and cut slices) were used to perform a subsequent dual annealing at 900 °C (500 hrs), 800 °C (1000 hrs), 700 °C (1000 hrs), and 600 °C (4500 hrs), respectively. The second annealing induced phase precipitation from the supersaturated solid solutions that were created during the first 1200 °C annealing. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to identify the phases and precipitation locations in order to obtain the compositions to construct the isothermal sections of both ternary systems at four different temperatures. The major results obtained from this study are isothermal sections of the Fe-Cr-Ni and Fe-Cr-Mo systems at 1200 °C, 900 °C, 800 °C, and 700 °C. For the Fe-Cr-Ni system, the results from DADMs agree with the majority of the literature results except for results at both 800 °C and 700 °C where the solubility of Cr in the fcc phase was found to be significantly higher than what was computed from thermodynamic calculations using the TCFE5 database. Overall, it seems that the Fe-Cr-Ni thermodynamic assessment only needs slight improvement to

Development of an EAM potential for simulation of radiation damage in Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wallenius, J.; Abrikosov, I.A.; Chakarova, R.; Lagerstedt, C. E-mail: christina@neutron.kth.se; Malerba, L.; Olsson, P.; Pontikis, V.; Sandberg, N.; Terentyev, D

2004-08-01

We have developed a set of EAM potentials for simulation of Fe-Cr alloys. By relaxing the requirement of reproducing the pressure-volume relation at short distances and by fitting to the thermal expansion coefficients of Fe and Cr, stability of the <1 1 0> self-interstitial could be obtained. For Cr, properties of the paramagnetic state were applied, providing a positive Cauchy pressure. Mixed Fe-Cr pair potentials were fitted to the calculated mixing enthalpy of ferromagnetic Fe-Cr. Simulation of thermal ageing in Fe-Cr alloys using the Fe-20Cr potential exhibited pronounced Cr-precipitation for temperatures below 900 K, a feature not observed at any temperature using a potential fitted to the mixing enthalpy of Fe-5Cr.

Viability of thin wall tube forming of ATF FeCrAl

Energy Technology Data Exchange (ETDEWEB)

Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-09-16

Fabrication of thin walled tubing of FeCrAl alloys is critical to its success as a candidate enhanced accident-tolerant fuel cladding material. Alloys that are being investigated are Generation I and Generation II FeCrAl alloys produced at ORNL and an ODS FeCrAl alloy, MA-956 produced by Special Metals. Gen I and Gen II FeCrAl alloys were provided by ORNL and MA-956 was provided by LANL (initially produced by Special Metals). Three tube development efforts were undertaken. ORNL led the FeCrAl Gen I and Gen II alloy development and tube processing studies through drawing tubes at Rhenium Corporation. LANL received alloys from ORNL and led tube processing studies through drawing tubes at Century Tubing. PNNL led the development of tube processing studies on MA-956 through pilger processing working with Sandvik Corporation. A summary of the recent progress on tube development is provided in the following report and a separate ORNL report: ORNL/TM-2015/478, “Development and Quality Assessments of Commercial Heat Production of ATF FeCrAl Tubes”.

Fundamental investigation of point defect interactions in FE-CR alloys

International Nuclear Information System (INIS)

Wirth, B.D.; Lee, H.J.; Wong, K.

2008-01-01

Full text of publication follows. Fe-Cr alloys are a leading candidate material for structural applications in Generation TV and fusion reactors, and there is a relatively large database on their irradiation performance. However, complete understanding of the response of Fe-Cr alloys to intermediate-to-high temperature irradiation, including the radiation induced segregation of Cr, requires knowledge of point defect and point defect cluster interactions with Cr solute atoms and impurities. We present results from a hierarchical multi-scale modelling approach of defect cluster behaviour in Fe-Cr alloys. The modelling includes ab initio electronic structure calculations performed using the VASP code with projector-augmented electron wave functions using PBE pseudo-potentials and a collinear treatment of magnetic spins, molecular dynamics using semi-empirical Finnic-Sinclair type potentials, and kinetic Monte Carlo simulations of coupled defect and Cr transport responsible for microstructural evolution. The modelling results are compared to experimental observations in both binary Fe-Cr and more complex ferritic-martensitic alloys, and provide a basis for understanding a dislocation loop evolution and the observations of Cr enrichment and depletion at grain boundaries in various irradiation experiments. (authors)

Hydrogen solubility in austenite of Fe-Ni-Cr alloys

International Nuclear Information System (INIS)

Zhirnova, V.V.; Mogutnov, B.M.; Tomilin, I.A.

1981-01-01

Hydrogen solubility in Fe-Ni-Cr alloys at 600-1000 deg C is determined. Hydrogen solubility in ternary alloys can not be predicted on the basis of the data on its solubility in binary Fe-Ni, Fe-Cr alloys. Chromium and nickel effect on hydrogen solubility in iron is insignificant in comparison with the effect of these elements on carbon or nitrogen solubility [ru

Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

Energy Technology Data Exchange (ETDEWEB)

Nickel, B.

2001-07-01

The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

Synthesis and characterization of Cr doped CoFe2O4

Science.gov (United States)

Verma, Kavita; Patel, K. R.; Ram, Sahi; Barbar, S. K.

2016-05-01

Polycrystalline samples of pure and Cr-doped cobalt ferrite (CoFe2O4 and CoCrFeO4) were prepared by solid state reaction route method. X-ray diffraction pattern infers that both the samples are in single phase with Fd3m space group. Slight reduction in the lattice parameter of CoCrFeO4 has been observed as compared to CoFe2O4. The dielectric dispersion has been explained on the basis of Fe2+ ↔ Fe3+ hopping mechanism. The polarizations at lower frequencies are mainly attributed to electronic exchange between Fe2+ ↔ Fe3+ ions on the octahedral site in the ferrite lattice. In the present system a part from n-type charge carrier (Fe3+/Fe2+), the presence of (Co3+/Co2+) ions give rise to p-type charge carrier. Therefore in addition to n-type charge carrier, the local displacement of p-type charge carrier in direction of external electric field also contributes to net polarization. However, the dielectric constant and loss tangent of CoCrFeO4 are found to be lower than CoFe2O4 and is attributed to the availability of ferrous ion. CoCrFeO4 have less amount of ferrous ion available for polarization as compared to that of CoFe2O4. The impedance spectra reveal a grain interior contribution to the conduction process.

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

International Nuclear Information System (INIS)

Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E.

2014-01-01

Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH) 3 ·3H 2 O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH) 3 (am) was stable with a solubility lower than 50 μg/l in the range 5.7 0.75 Cr 0.25 (OH) 3 , the stability region was extended to 4.8 3 ·xH 2 O whereas in the presence of iron the precipitate is a mixed Fe (1−x) Cr x (OH) 3 phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe x ,Cr 1−x )(OH) 3 hydroxides as compared to the stability of Cr(OH) 3 . We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH) 3 ·3H 2 O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH) 3 (am) phase. Mixed Fe 0.75 Cr 0.25 (OH) 3 hydroxides were found to be of the ferrihydrite structure, Fe(OH) 3 , and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr(III) hydroxides are more effective enhancers of groundwater quality, in comparison to the plain amorphous or crystalline Cr(III) hydroxides, the latter found to have a solubility typically higher than 50 μg/l (maximum EU permitted Cr level in drinking water), while the amorphous Cr(OH) 3 (am) phase was within the drinking water threshold in the range 5.7 0.75 Cr 0.25 (OH) 3 hydroxides studied were of extended stability in the 4.8 < pH < 13.5 range

Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys

International Nuclear Information System (INIS)

Geribola, Gulherme Altomari

2014-01-01

Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H 2 /2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

Grain boundary segregation in FeCrNi model alloys; Korngrenzensegregation in FeCrNi-Modellegierungen

Energy Technology Data Exchange (ETDEWEB)

Schlueter, B.; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Muraleedharan, P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy

1998-12-31

P and S segregate at the grain boundaries and thus increase susceptibility to intergranular corrosion at those sites. This could be proven by means of nitric acid-chromate tests and potentiostatic etching tests. There is a direct connection between loss in mass, mean depth of intergranular corrosion attacks, dissolution current density, and level of segregation-induced concentration of P and S at the grain boundaries. The segregation effect at these sites was found to be most evident in specimens of the examined Fe-Cr-Ni steel which had been heat-treated for 1000 hours at 550 C. However, segregation occurs also in materials that received a heat treatment of 400 C/5000 hours, while intergranular corrosion is observed only after heat treatment of 500 C/1000 hours. Apart from segregation of P, formation of Cr-rich phosphides is observed, which leads to depletion of Cr at the precipitates. (orig./CB) [Deutsch] P und S segregieren an die KG und erhoehen dort die IK-Anfaelligkeit. Dies konnte mit Hilfe von Salpetersaeure-Chromat- und Potentiostatischem Aetztest nachgewiesen werden. Es besteht ein direkter Zusammenhang zwischen Masseverlust, mittlerer IK-Angriffstiefe, Aufloesungsstromdichte und Hoehe der segregationsbedingten Anreicherungen von P und S an den KG. Der KG-Segregationseffekt am untersuchten Fe-Cr-Ni-Stahl ist im Waermebehandlungszustand 550 C/1000 h am deutlichsten ausgepraegt. Aber auch bereits bei 400 C/5000 h findet Segregation statt. IKSpRK tritt nur im Waermebehandlungszustand 550 C/1000 h auf. Neben der P-Segregation wird die Bildung Cr-reicher Phosphide beobachtet, die zur Abreicherung von Cr an den Ausscheidungen fuehrt. (orig.)

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

Energy Technology Data Exchange (ETDEWEB)

Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E., E-mail: gantipas@metal.ntua.gr

2014-01-15

Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH){sub 3}·3H{sub 2}O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH){sub 3}(am) was stable with a solubility lower than 50 μg/l in the range 5.7 < pH < 11. • For mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3}, the stability region was extended to 4.8 < pH < 13.5. -- Abstract: Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH){sub 3}·xH{sub 2}O whereas in the presence of iron the precipitate is a mixed Fe{sub (1−x)}Cr{sub x}(OH){sub 3} phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe{sub x},Cr{sub 1−x})(OH){sub 3} hydroxides as compared to the stability of Cr(OH){sub 3}. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH){sub 3}·3H{sub 2}O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH){sub 3}(am) phase. Mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3} hydroxides were found to be of the ferrihydrite structure, Fe(OH){sub 3}, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr

Hydrogen permeation in FeCrAl alloys for LWR cladding application

Science.gov (United States)

Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

2015-06-01

FeCrAl, an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In this study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. The total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

The microstructure of neutron-irradiated Fe-Cr alloys: A small-angle neutron scattering study

International Nuclear Information System (INIS)

Heintze, C.; Bergner, F.; Ulbricht, A.; Eckerlebe, H.

2009-01-01

Ferritic-martensitic chromium steels are candidate materials for future applications in both Gen-IV fission and fusion technology. Experimental investigation of neutron-irradiated Fe-Cr model alloys is important in order to gain a better understanding of the interplay of chromium content and irradiation behaviour. Small-angle neutron scattering (SANS) is particularly well suited to unfold the size distribution of non-planar irradiation-induced nanoscale features such as defect-solute clusters, nanovoids and α'- particles. This size distribution represents a statistically reliable average over a macroscopic volume. Assumptions on the dominant type of features can be checked against the ratio of magnetic and nuclear scattering. The materials investigated in this work are commercial-purity Fe-Cr alloys of nominal compositions Fe-2.5Cr, Fe-5Cr, Fe- 9Cr and Fe-12.5Cr (at %). Neutron irradiation was performed in the reactor BR2 at Mol (Belgium) at a temperature of 300 deg. C and neutron flux of 9 x 10 13 cm -2 s -1 (E > 1 MeV) [Matijasevic, JNM 377 (2008) 147]. The neutron exposures expressed in units of displacements per atom correspond to 0.6 and 1.5 dpa. A wavelength of 0.58 nm and three detector-sample distances of 1, 4 and 16 m were used in the SANS experiments carried out at the SANS-2 facility of GKSS Geesthacht (Germany). The samples were placed in a saturation magnetic field in order to separate magnetic and nuclear contributions. The scattering curves obtained for the unirradiated conditions of the four Fe-Cr alloys were taken as reference. We have found that the volume fraction of scatterers slightly increases with neutron exposure (Fe-9Cr) or exhibits a saturation-like behaviour (Fe-2.5Cr, Fe-5Cr and Fe-12.5Cr) and that the volume fraction at 1.5 dpa is an increasing function of the chromium level with a slight increase up to 9 at%Cr and a steep increase between 9 and 12.5 at%Cr. The radii of irradiation-induced scatterers are essentially less than 8 nm and

Atomistic simulation of the influence of Cr on the mobility of the edge dislocation in Fe(Cr) alloys

International Nuclear Information System (INIS)

Hafez Haghighat, S.M.; Terentyev, D.; Schaeublin, R.

2011-01-01

In this work Fe-Cr compounds, as model alloys for the ferritic base steels that are considered as main candidates for the structural materials of the future fusion reactors, are studied using molecular dynamics simulations. The Cr or so-called α' precipitates, which are obstacles to dislocations, affect mechanical properties, leading to hardening and loss of ductility. The flow stress to move an edge dislocation in a Cr solid solution in pure Fe is studied as a function of Cr content. The strength of a nanometric Cr precipitate as obstacle to an edge dislocation in pure Fe is investigated as a function of its Cr content. Results show that with increasing Cr content the precipitate obstacle strength increases, with a strong sensitivity to the local atomic order. Temperature induces a monotonic decrease of the flow stress of the Cr solid solution and of the Cr precipitate obstacle strength.

First-principles investigation of Cr-doped Fe2B: Structural, mechanical, electronic and magnetic properties

Science.gov (United States)

Wei, Xiang; Chen, Zhiguo; Zhong, Jue; Wang, Li; Wang, Yipeng; Shu, Zhongliang

2018-06-01

The structural, mechanical, electronic and magnetic properties of Fe8-xCrxB4 (x = 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7 and 8) have been investigated by first-principles calculation. It was found that the calculated structural parameters are well consistent with available experimental data. Moreover, all studied compounds are thermodynamically stable phases. On the whole, the moduli of the compounds firstly increase and then decrease with the increase of Cr concentration, whereas the variation of hardness exhibits more fluctuations. All Cr-doped Fe2B have better ductility than Fe2B except Fe2Cr6B4 and Fe5Cr3B4. Interestingly, Fe4Cr4B4 is of not only the slightly larger hardness, but also much better ductility than Fe2B. As the Cr concentration is lower than 20 wt%, the hardness of Cr-doped Fe2B slightly decreases with increasing Cr, whereas the sharply increased hardness of (Fe, Cr)2B in Fe-B alloys or boriding layer should be attributed to the multiple alloying effects resulting from Cr and the other alloying elements. The electronic structures revealed that the Fe-B and/or Cr-B bonds are mainly responsible for their mechanical properties, and the M-N (M = Fe or Cr, N = Fe or Cr) bonds in 〈2 2 0〉 and 〈1 1 3〉 orientations show covalent character. Additionally, the magnetic moments (Ms) of the compounds do not monotonically decrease with increasing Cr.

Characterization of transparent superconductivity Fe-doped CuCrO{sub 2} delafossite oxide

Energy Technology Data Exchange (ETDEWEB)

Taddee, Chutirat [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Kamwanna, Teerasak, E-mail: teekam@kku.ac.th [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand); Amornkitbamrung, Vittaya [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand)

2016-09-01

Graphical abstract: - Highlights: • Effect of Fe substitution on the physical properties in CuCrO{sub 2} is studied. • The substitution of Cr{sup 3+} by Fe{sup 3+} produces a mixed effect on the magnetic properties. • CuCr{sub 1−x}Fe{sub x}O{sub 2} delafossite oxides show transparent superconductivity. - Abstract: Delafossite CuCr{sub 1−x}Fe{sub x}O{sub 2} (0.0 ≤ x ≤ 0.15) semiconductors were synthesized using a self-combustion urea nitrate process. The effects of Fe concentration on its microstructural, optical, magnetic, and electrical properties were investigated. X-ray diffraction (XRD) analysis results revealed the delafossite structure in all the samples. The lattice spacing of CuCr{sub 1−x}Fe{sub x}O{sub 2} slightly increased with increasing substitution of Fe at the Cr sites. The optical properties measured at room temperature using UV–visible spectroscopy showed a weak absorbability in the visible light and near IR regions. The corresponding direct optical band gap was about 3.61 eV, exhibiting transparency in the visible region. The magnetic hysteresis loop measurements showed that the Fe-doped CuCrO{sub 2} samples exhibited ferromagnetic behavior at room temperature. This indicated that the substitution of Fe{sup 3+} for Cr{sup 3+} produced a mixed effect on the magnetic properties of CuCrO{sub 2} delafossite oxide. The temperature dependent resistivity measurements clearly revealed the presence of superconductivity in the CuCr{sub 1−x}Fe{sub x}O{sub 2} with a superconducting transition up to 118 K.

Ab initio study of Cr interactions with point defects in bcc Fe

International Nuclear Information System (INIS)

Olsson, P.; Domain, Ch.; Wallenius, J.

2008-01-01

Full text of publication follows. Ferritic martensitic steels are candidate structural materials for fast neutron reactors, and in particular high-Cr reduced-activation steels. In Fe-Cr alloys, Cr plays a major role in the radiation-induced evolution of the mechanical properties. Using ab initio calculations based on density functional theory, the properties of Cr in α-Fe have been investigated. The intrinsic point defect formation energies were found to be larger in model bcc Cr as compared to those in ferromagnetic bcc Fe. The interactions of Cr with point defects (vacancy and self interstitials) have been characterised. Single Cr atoms interact weakly with vacancies but significantly with self-interstitial atoms. Mixed interstitials of any interstitial symmetry are bound. Configurations where two Cr atoms are in nearest neighbour position are generally unfavourable in bcc Fe except when they are a part of a interstitial complex. Mixed interstitials do not have as strong directional stability as pure Fe interstitials have. The effects on the results using the atom description scheme of either the ultrasoft pseudo-potential (USPP) or the projector augmented wave (PAW) formalisms are connected to the differences in local magnetic moments that the two methods predict. As expected for the Fe-Cr system, the results obtained using the PAW method are more reliable than the ones obtained with USPP. (authors)

Magnetic properties of point defect interaction with impurity atoms in Fe-Cr alloys

Science.gov (United States)

Nguyen-Manh, D.; Lavrentiev, M. Yu.; Dudarev, S. L.

2009-04-01

An integrated ab initio and statistical Monte Carlo investigation has been recently carried out to model the thermodynamic and kinetic properties of Fe-Cr alloys. We found that the conventional Fe-Cr phase diagram is not adequate at low temperature region where the magnetic contribution to the free energy plays an important role in the prediction of an ordered Fe 15Cr phase and its negative enthalpy of formation. The origin of the anomalous thermodynamic and magnetic properties of Fe-Cr alloys can be understood using a tight-binding Stoner model combined with the charge neutrality condition. We investigate the environmental dependence of magnetic moment distributions for various self-interstitial atom dumbbells configurations using spin density maps found using density functional theory calculations. The mixed dumbbell Fe-Cr and Fe-Mn binding energies are found to be positive due to magnetic interactions. Finally, we discuss the relationship between the migration energy of vacancy in Fe-Cr alloys and magnetism at the saddle point configuration.

Point defect properties of ternary fcc Fe-Cr-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Wróbel, J.S., E-mail: jan.wrobel@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D.; Dudarev, S.L. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland)

2017-02-15

Highlights: • Properties of point defects depend on the local atomic environment. • As the degree of chemical order increases, the formation energies increase, too. • Relaxation volumes are larger for the more ordered structures. - Abstract: The properties of point defects in Fe-Cr-Ni alloys are investigated, using density functional theory (DFT), for two alloy compositions, Fe{sub 50}Cr{sub 25}Ni{sub 25} and Fe{sub 55}Cr{sub 15}Ni{sub 30}, assuming various degrees of short-range order. DFT-based Monte Carlo simulations are applied to explore short-range order parameters and generate representative structures of alloys. Chemical potentials for the relevant structures are estimated from the minimum of the substitutional energy at representative atoms sites. Vacancies and 〈1 0 0〉 dumbbells are introduced in the Fe{sub 2}CrNi intermetallic phase as well as in two Fe{sub 55}Cr{sub 15}Ni{sub 30} alloy structures: the disordered and short range-ordered structures, generated using Monte Carlo simulations at 2000 K and 300 K, respectively. Formation energies and relaxation volumes of defects as well as changes of magnetic moments caused by the presence of defects are investigated as functions of the local environment of a defect.

Electrical transport properties in Fe-Cr nanocluster-assembled granular films

Science.gov (United States)

Wang, Xiong-Zhi; Wang, Lai-Sen; Zhang, Qin-Fu; Liu, Xiang; Xie, Jia; Su, A.-Mei; Zheng, Hong-Fei; Peng, Dong-Liang

2017-09-01

The Fe100-xCrx nanocluster-assembled granular films with Cr atomic fraction (x) ranging from 0 to 100 were fabricated by using a plasma-gas-condensation cluster deposition system. The TEM characterization revealed that the uniform Fe clusters were coated with a Cr layer to form a Fe-Cr core-shell structure. Then, the as-prepared Fe100-xCrx nanoclusters were randomly assembled into a granular film in vacuum environments with increasing the deposition time. Because of the competition between interfacial resistance and shunting effect of Cr layer, the room temperature resistivity of the Fe100-xCrx nanocluster-assembled granular films first increased and then decreased with increasing the Cr atomic fraction (x), and revealed a maximum of 2 × 104 μΩ cm at x = 26 at.%. The temperature-dependent longitudinal resistivity (ρxx), magnetoresistance (MR) effect and anomalous Hall effect (AHE) of these Fe100-xCrx nanocluster-assembled granular films were also studied systematically. As the x increased from 0 to 100, the ρxx of all samples firstly decreased and then increased with increasing the measuring temperature. The dependence of ρxx on temperature could be well addressed by a mechanism incorporated for the fluctuation-induced-tunneling (FIT) conduction process and temperature-dependent scattering effect. It was found that the anomalous Hall effect (AHE) had no legible scaling relation in Fe100-xCrx nanocluster-assembled granular films. However, after deducting the contribution of tunneling effect, the scaling relation was unambiguous. Additionally, the Fe100-xCrx nanocluster-assembled granular films revealed a small negative magnetoresistance (MR), which decreased with the increase of x. The detailed physical mechanism of the electrical transport properties in these Fe100-xCrx nanocluster-assembled granular films was also studied.

Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

Energy Technology Data Exchange (ETDEWEB)

Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

2015-07-01

The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

Inhibited Aluminization of an ODS FeCr Alloy

International Nuclear Information System (INIS)

Vande Put Ep Rouaix, Aurelie; Pint, Bruce A.

2012-01-01

Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small (∼ 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

Database on Performance of Neutron Irradiated FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States); Littrell, Ken [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parish, Chad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

The present report summarizes and discusses the database on radiation tolerance for Generation I, Generation II, and commercial FeCrAl alloys. This database has been built upon mechanical testing and microstructural characterization on selected alloys irradiated within the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to doses of 13.8 dpa at temperatures ranging from 200°C to 550°C. The structure and performance of these irradiated alloys were characterized using advanced microstructural characterization techniques and mechanical testing. The primary objective of developing this database is to enhance the rapid development of a mechanistic understanding on the radiation tolerance of FeCrAl alloys, thereby enabling informed decisions on the optimization of composition and microstructure of FeCrAl alloys for application as an accident tolerant fuel (ATF) cladding. This report is structured to provide a brief summary of critical results related to the database on radiation tolerance of FeCrAl alloys.

Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

International Nuclear Information System (INIS)

Jin, Y.; O'Connell, A.; Kharel, P.; Lukashev, P.; Staten, B.; Tutic, I.; Valloppilly, S.; Herran, J.; Mitrakumar, M.; Bhusal, B.; Huh, Y.; Yang, K.; Skomski, R.; Sellmyer, D. J.

2016-01-01

The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2 1 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T C ) significantly above room temperature. The measured T C for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ B /f.u. and 2.78 μ B /f.u., respectively, which are close to the theoretically predicted value of 3 μ B /f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

OpenAIRE

M. Mahmoudiniya; Sh. Kheirandish; M. Asadi Asadabad

2017-01-01

Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile st...

Diffusion of 51Cr along high-diffusivity paths in Ni-Fe alloys

International Nuclear Information System (INIS)

Cermak, J.

1990-01-01

Penetration profiles of 51 Cr in polycrystalline alloys Ni-xFe (x = 0, 20, 40, and 60 wt.% Fe) after diffusion anneals at temperatures between 693 and 1473 K are studied. Sectioning of diffusion zones of samples annealed above 858 K is carried out by grinding, at lower temperatures by DC glow discharge sputtering. The concentration of 51 Cr in depth x is assumed to be proportional to relative radioactivity of individual sections. With help of volume and pipe self-diffusion data taken from literature, the temperature dependence of product P = δD g (δ and D g are grain boundary width and grain boundary diffusion coefficient, respectively) is obtained: P = (2.68 - 0.88 +1.3 ) x 10 -11 exp [-(221.3 ± 3.0) kJ/mol/RT]m 3 /s. This result agrees well with the previous measurements of 51 Cr diffusivity in Fe-18 Cr-12 Ni and Fe-21 Cr-31 Ni. It indicates that the mean chemical composition of Fe-Cr-Ni ternary alloys is not a dominant factor affecting the grain boundary diffusivity of Cr in these alloys. (author)

Vector magnetometry of Fe/Cr/Fe trilayers with biquadratic coupling

International Nuclear Information System (INIS)

Mansell, R; Petit, D; Fernández-Pacheco, A; Lee, J H; Chin, S-L; Lavrijsen, R; Cowburn, R P

2017-01-01

The magnetic reversal of epitaxial Fe/Cr/Fe trilayer samples grown on GaAs is studied. In wedged samples both long and short period coupling oscillations associated with Ruderman–Kittel–Kasuya–Yosida (RKKY) coupling in Cr are seen in the easy axis saturation fields. By using vector vibrating sample magnetometry and both longitudinal and transverse magneto-optical Kerr effect magnetometry we are able to determine the exact reversal path of both the magnetic layers. Changes in the reversal behavior are seen with sub-monolayer changes of the thickness of the Cr interlayer. The two main reversal paths are described in terms of whether the reversal is dominated by bilinear RKKY coupling, which leads to an antiparallel state at remanence or by biquadratic coupling which leads to a 90 degree alignment of layers at remanence. The changing reversal behaviour is discussed with respect to the possibility of using such systems for multilayer memory applications and, in particular, the limits on the required accuracy of the sample growth. (letter)

Effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Gao, R.S. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: zhenl@hit.edu.cn; Li, G.A. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2006-07-15

The effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets has been investigated. The magnetic flux loss of two kinds of magnets before and after irradiation was measured. Results show that the effect of {gamma}-ray irradiation on the magnetic properties of sintered NdFeB is not so obvious as that on Fe-Cr-Co magnet. Irradiation-induced damage from {gamma}-ray for the Fe-Cr-Co magnets was characterized for the first time. The decline of permanent magnetic properties of Fe-Cr-Co magnet induced by {gamma}-ray irradiation is reversible except for the maximum energy product (BH){sub max}. The difference of coercivity mechanism between these two kinds of permanent magnets is responsible for the different dependence of magnetic properties loss induced by {gamma}-ray irradiation.

Partial amorphization of an α-FeCr alloy by ball-milling

International Nuclear Information System (INIS)

Loureiro, J. M.; Costa, B. F. O.; Caer, G. Le; Delcroix, P.

2008-01-01

The structural changes of near-equiatomic α-FeCr alloys, ground in a vibratory mill in vacuum and in argon, were followed as a function of milling time. An amorphous phase forms in both cases but at a much faster rate when milling in argon than when milling in vacuum. Amorphisation by ball-milling of α-FeCr alloys is deduced to be an intrinsic phenomenon which is however speeded-up by oxygen. The amorphous phase crystallizes into a bcc Cr-rich phase and a bcc Fe-rich phase when annealed for short times.

Exchange bias in Fe/Cr double superlattices

International Nuclear Information System (INIS)

Jiang, J. S.; Felcher, G. P.; Inomata, A.; Goyette, R.; Nelson, C.; Bader, S. D.

1999-01-01

Utilizing the oscillatory interlayer exchange coupling in Fe/Cr superlattices, we have constructed ''double superlattice'' structures where a ferromagnetic (F) and an antiferromagnetic (AF) Fe/Cr superlattice are coupled through a Cr spacer. The minor hysteresis loops in the magnetization are shifted from zero field, i.e., the F superlattice is exchange biased by the AF one. The double superlattices are sputter-deposited with (211) epitaxy and possess uniaxial in-plane magnetic anisotropy. The magnitude of the bias field is satisfactorily described by the classic formula for collinear spin structures. The coherent structure and insensitivity to atomic-scale roughness makes it possible to determine the spin distribution by polarized neutron reflectivity, which confirms that the spin structure is collinear. The magnetic reversal behavior of the double superlattices suggests that a realistic model of exchange bias needs to address the process of nucleating local reverse domains

Exchange bias in Fe/Cr double superlattices

International Nuclear Information System (INIS)

Jiang, J. S.; Felcher, G. P.; Inomata, A.; Goyette, R.; Nelson, C. S.; Bader, S. D.

2000-01-01

Utilizing the oscillatory interlayer exchange coupling in Fe/Cr superlattices, we have constructed ''double superlattice'' structures where a ferromagnetic (F) and an antiferromagnetic (AF) Fe/Cr superlattice are coupled through a Cr spacer. The minor hysteresis loops in the magnetization are shifted from zero field, i.e., the F superlattice is exchange biased by the AF one. The double superlattices are sputter deposited with (211) epitaxy and possess uniaxial in-plane magnetic anisotropy. The magnitude of the bias field is satisfactorily described by the classic formula for collinear spin structures. The coherent structure and insensitivity to atomic-scale roughness makes it possible to determine the spin distribution by polarized neutron reflectivity, which confirms that the spin structure is collinear. The magnetic reversal behavior of the double superlattices suggests that a realistic model of exchange bias needs to address the process of nucleating local reverse domains. (c) 2000 American Vacuum Society

CoCr/NiFe double layers studied by FMR and VSM

NARCIS (Netherlands)

Stam, M.T.H.C.W.; Gerritsma, G.J.; Lodder, J.C.; Popma, T.J.A.

1987-01-01

CoCr/NiFe double layers were investigated by FMR and VSM. The FMR linewidth of NiFe of the double layer is about twice that of a single NiFe layer. The resonance field is the same in both cases. Using the VSM the coercive field of the CoCr layer of the double layer was obtained. It is approximately

Capture cross sections for Cr, Fe and Ni

International Nuclear Information System (INIS)

Corvi, F.

1990-01-01

Since stainless steel represents about 25% of the volume of a fast power reactor, its constituent elements strongly influence its two main neutronic parameters: critical enrichment and breeding gain. Also, capture in the narrow p and d-wave resonances of Cr, Fe and Ni contributes as much as 10 to 15% of the Doppler coefficient of reactivity. Following sensitivity calculations, typical accuracy requirements in the energy range 0.1-100 keV are 5-10% for capture in Fe and 10-20% for capture in Ni and Cr. 11 refs, 2 tabs

Electroless siliconizing Fe-3% Cr-3% Si alloy

International Nuclear Information System (INIS)

Nurlina, Enung; Darmono, Budy; Purwadaria, Sunara

2000-01-01

In this research Fe-3%Cr-3%Mo-3%Si and Fe-3%Cr-3%Cu-3%Si alloys had been coated by silicon metal without electricity current which knows as electroless siliconizing. Coating was conducted by immersed sampler into melt fluoride-chloride salt bath at temperature of 750 o C for certain period. The layer consisted of Fe3Si phase. Observation by microscope optic and EDAX showed that the silicide layer were thick enough, adherent, free for crack and had silicon content on the surface more than 15%. The growth rate of silicide layer followed parabolic rate law, where the process predominantly controlled by interdiffusion rate in the solid phase. Key words : electroless siliconizing, the melt fluoride- chloride salt mix, silicide layer

Oxidation performance of a Fe-13Cr alloy with additions of rare earth elements

International Nuclear Information System (INIS)

Martinez-Villafane, A.; Chacon-Nava, J.G.; Gaona-Tiburcio, C.; Almeraya-Calderon, F.; Dominguez-Patino, G.; Gonzalez-Rodriguez, J.G.

2003-01-01

The influence of rare earth elements (REE's) i.e. Neodymium (Nd) and Praseodymium (Pr) on the oxidation behavior of a Fe-13Cr alloy has been studied, and its role on the oxidation rate and oxide morphology and formation is discussed. Specimens were isothermally oxidized in oxygen at 800 deg. C for 24 h. It was found that a small addition (≤0.03 wt.%) of either Nd or Pr, reduced the oxidation rate of the Fe-13Cr base alloy. Moreover, the simultaneous addition of both elements to the alloy produced a dramatic reduction in the oxidation kinetics. Analysis by scanning electronic microscope (SEM) revealed that the morphology of oxides formed on Fe-13Cr specimens with and without REE's specimens was very different. In fact, a fine-grained oxide morphology was observed for alloys with REE's addition. For these alloys only, chromium enrichment at the metal/scale interface was observed. From transmission electronic microscope (TEM) analysis, it was found the following: at the early stages of oxide formation, after 0.25 h, Cr 2 O 3 , Fe 3 O 4 , α-Fe 2 O 3 and γ-Fe 2 O 3 were formed; at 6 h, Cr 2 O 3 , FeCr 2 O 4 and α-Fe 2 O 3 were identified and, for exposure times greater than 6 h, Cr 2 O 3 , α-Fe 2 O 3 and a spinel which was presumably transformed into a solid solution (Fe 2 O 3 ·Cr 2 O 3 ) were found

Effects of composition and heat treatments on the strength and ductility of Fe-Cr-Co alloys

International Nuclear Information System (INIS)

Kubarych, K.G.

1980-06-01

The relationship between the microstructure and mechanical properties of spinodally decomposed Fe-Cr-Co ductile permanent magnet alloys was investigated using transmission electron microscopy, electron diffraction, tensile testing, and Charpy impact testing. Isothermal aging and step aging of four alloys (Fe-28 wt % Cr-15 wt % Co, Fe-23 wt % Cr-15-wt % Co-5 wt % V, Fe-23 wt % Cr-15 wt % Co-3 wt % V-2 wt % Ti, and Fe-31 wt % Cr-23 % Co) resulted in decomposition into two phases, an Fe-Co rich (α 1 ) phase and a Cr rich (α 2 ) phase. The microstructural features of the decomposition products were consistent with those expected from a spinodal reaction and agree with the reported work on the Fe-Cr-Co system. An Fe-23 wt % Cr-15 wt % Co-5 wt % V alloy was found to have, among the four alloys, the best combinations of strength and ductility

Corrosion behaviour of Nd-Fe-B magnets containing Co and Cr

International Nuclear Information System (INIS)

Pawlowska, G.; Bala, H.; Szymura, S.

1993-01-01

The effect of partial substitution of iron by Co and Cr on corrosion behaviour of Nd 16 Fe 76 B 8 permanent magnets has been investigated. Small additions of Cr (1 to 4%at) are enough to ensure maximal corrosion inhibition. Greater amount of Cr into Nd-Fe-B alloy (>8%at), against expectations, practically do not affect the corrosion behaviour and additionally, considerably worsen its magnetic properties. Corrosion tests have shown a distinct effect of cobalt addition on the inhibition of both acid corrosion and the abnormal dissolution process of the Nd-Fe-Co-B magnets. Cobalt additions inhibit the atmosphere corrosion of Nd-Fe-B permanent magnets, especially a salt-spray environment. (author). 6 refs, 4 figs, 1 tab

Microstructures of neutron-irradiated Fe-12Cr-XMn (X=15-30) ternary alloys

International Nuclear Information System (INIS)

Miyahara, K.; Hosoi, Y.; Garner, F.A.

1992-01-01

The objective of this effort is to determine the factors which control the stability of irradiated alloys proposed for reduced activation applications. The Fe-Cr-Mn alloy system is being studied as an alternative to the Fe-Cr-Ni system because of the need to reduce long-term radioactivation in fusion-power devices. In this study, four Fe-12Cr-XMn (X =15, 20, 25, 30 wt%) alloys were irradiated in the Fast Flux Test Facility to 20 dpa at 643K and 40 dpa at 679, 793, and 873K to investigate the influence of manganese content on void swelling and phase stability. The results confirm and expand the results of earlier studies that indicate that the Fe-Cr-Mn system is relatively unstable compared to that of the Fe-Cr-Ni system, with alpha and sigma phases forming as a consequence of thermal aging or high temperature irradiation

Quasicrystalline and crystalline phases in Al65Cu20(Fe, Cr)15 alloys

International Nuclear Information System (INIS)

Liu, W.; Koester, U.; Mueller, F.; Rosenberg, M.

1992-01-01

Two types of icosahedral quasicrystals are observed in Al 65 Cu 20 Fe 15-x Cr x (0 ≤ x ≤ 15) alloys, the face-centred AlCuFe-type icosahedral phase with dissoluted Cr and the primitive AlCuCr-type icosahedral phase with dissoluted Fe. In the vicinity of Al 65 Cu 20 Fe 8 Cr 7 a stable decagonal phase (a=0.45 nm and c=1.23 nm) forms competitively with the icosahedral quasicrystals. All these three quasicrystalline phases can be regarded as Hume-Rothery phases stabilized by the energy band factor. The density is measured to be 4.57, 4.44, and 4.11 g/cm 3 for the icosahedral Al 65 Cu 20 Fe 15 , the decagonal Al 65 Cu 20 Fe 8 Cr 7 , and the icosahedral Al 65 Cu 20 Cr 15 alloys, respectively. Depending on the composition in the range between Al 65 Cu 20 Fe 8 Cr 7 and Al 65 Cu 20 Cr 15 , several crystalline phases are observed during the transormation of the AlCuCr-type icosahedral phase: the 1/1-3/2-type orthorhombic (o) and the 1/0-3/2-type tetragonal (t) approximants of the decagonal phase, a hexagonal (h) phase, as well as a long-range vacancy ordered τ 3 -phase derived from a CsCl-type structure with a=0.2923 nm. The structures of all the crystalline phases are closely related to those of the icosahedral (i) and decagonal (d) quasicrystals, which leads to a definite orientation relationship as follows: i5 parallel d10 parallel o[100] parallel t[100] parallel h[001] parallel τ 3 [110]. (orig.)

Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys; Influencia da composicao quimica na textura cristalografica de ligas Fe-Cr-Mo

Energy Technology Data Exchange (ETDEWEB)

Moura, L.B.; Guimaraes, R.F. [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, Fortaleza, CE (Brazil). Dept. da Industria; Abreu, H.F.G. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil)

2010-07-01

The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

Radiation damage in Fe-Cr alloys: Atomistic studies

International Nuclear Information System (INIS)

Terentyev, Dmitry; Malerba, Lorenzo; Bonny, Giovanni; Castin, Nicolas

2009-01-01

High-Cr ferritic-martensitic steels are the most promising candidate structural materials for future advanced fission reactors, as well as for fusion systems, due to their better thermomechanical properties and higher radiation resistance as compared to austenitic steels. The performance of these steels, especially under irradiation, appears to be largely determined by the Cr content. For instance, the current choice of steel compositions around ∼9 wt% Cr is mainly based on the observation of a local minimum in the ductile-brittle transition temperature shift at this composition. On the other hand, reduced void swelling is observed between 3 and 12 wt% Cr. The origin of these and other Cr-dependent effects remained unexplained for a long time, thereby calling for a physical modelling effort addressing these questions. In this presentation, an overview is given on the effort made in recent years to construct a whole modelling framework, from ab initio to dislocations, to provide explanations to the above-mentioned issues. Ab initio calculations combined to the development of the interatomic potentials capable of grasping key features of Cr atoms embedded in perfect and defected Fe matrix, were required. Primary damage, defect migration, Cr mass transport, phase separation, Cr-defect segregation and dislocation-defect interactions could then be studied using fully atomistic approaches. Our research shows that many of the effects of Cr content on the behaviour of these alloys under irradiation can be attributed to the only recently highlighted high solubility of Cr in Fe (∼10 wt%), below which, in addition, Cr atoms tend to order. The presentation will clarify how this aspect, combined with the high affinity between Cr atoms and self-interstitials defects, influences and partly explain both microstructure evolution and mechanical behaviour of high-Cr steels under irradiation. (author)

Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

Energy Technology Data Exchange (ETDEWEB)

Ohno, S.; Shimakura, H. [Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Tahara, S. [Faculty of Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213 (Japan); Okada, T. [Niigata College of Technology, Kamishin’eicho, Nishi-ku, Niigata 950-2076 (Japan)

2015-08-17

The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

An ab initio study on the structural, electronic and mechanical properties of quaternary full-Heusler alloys FeMnCrSn and FeMnCrSb

Science.gov (United States)

Erkişi, Aytaç

2018-06-01

The quaternary full Heusler alloys FeMnCrSn and FeMnCrSb, which have face-centred cubic (FCC) crystal structure and conform to ? space group with 216 space number, have been investigated using Generalised Gradient Approximation (GGA) in the Density Functional Theory (DFT) as implemented in VASP (Vienna Ab initio Simulation Package) software. These alloys are considered in ferromagnetic (FM) order. After the investigation of structural stability of these alloys, their mechanical and thermal properties and also electronic band structures have been examined. The calculated spin-polarised electronic band structures and total electronic density of states (DOS) within GGA approximation show that these alloys can exhibit both metallic and half-metallic characters in different structural phases. The calculated formation enthalpies and the plotted energy-volume graphs show that Type-III phase is most stable structural phase for these materials. Also, FeMnCrSb alloy in Type-I/Type-III phases and FeMnCrSn alloy in Type-III phase show half-metallic behaviour with integer total magnetic moments almost 2 and 1 μB per formula unit, respectively, since there are band gaps observed in spin-down states, whereas they have metallic behaviour in majority bands. Other structural phases of both systems are also metallic. Moreover, the calculated elastic constants and the estimated anisotropy shear factors indicate that these materials are stable mechanically in all of three phases except FeMnCrSn in Type-I phase that does not satisfy Born stability criteria in this phase and have high anisotropic behaviour.

Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

Energy Technology Data Exchange (ETDEWEB)

Pal, Pampa [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Majumdar, A.K., E-mail: akm@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Ramakrishna Mission Vivekananda University, PO Belur Math, Howrah 711202 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

2015-05-01

We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used.

HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

Directory of Open Access Journals (Sweden)

M. Mahmoudiniya

2017-03-01

Full Text Available Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile strength and toughness were higher than those of 316 steel at 25, 200,350 and 500°C. In contrast with 316 steel, the new FeCrMn steel did not show strain induced transformation and dynamic strain aging phenomena during tensile tests that represented higher austenite stability of new developed steel. Lower density and higher strength of the new steel caused higher specific strength in comparison with the 316 one that can be considered as an important advantage in structural applications but in less corrosive environment

Phase separation in equiatomic AlCoCrFeNi high-entropy alloy

Energy Technology Data Exchange (ETDEWEB)

Manzoni, A., E-mail: anna.manzoni@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany); Daoud, H.; Völkl, R.; Glatzel, U. [Metals and Alloys, University Bayreuth, Ludwig-Thoma-Strasse 36b, D-95447 Bayreuth (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany)

2013-09-15

The microstructure of the as-cast AlCoCrFeNi high entropy alloy has been investigated by transmission electron microscopy and atom probe tomography. The alloy shows a very pronounced microstructure with clearly distinguishable dendrites and interdendrites. In both regions a separation into an Al–Ni rich matrix and Cr–Fe-rich precipitates can be observed. Moreover, fluctuations of single elements within the Cr–Fe rich phase have been singled out by three dimensional atom probe measurements. The results of investigations are discussed in terms of spinodal decomposition of the alloying elements inside the Cr–Fe-rich precipitates. - Highlights: ► The Alloy separates into an Al–Ni rich matrix and Cr–Fe-rich precipitates. ► Concentration depth profiles in the Cr–Fe rich regions show opposite fluctuations. ► They have been attributed to the spinodal decomposition of Fe- and Cr-rich phases. ► The Al–Ni rich region corresponds well to the Al–Ni rich phases observed in the 6 component AlCoCrCuFeNi alloy.

Microstructure characterization and strengthening mechanisms of oxide dispersion strengthened (ODS) Fe-9%Cr and Fe-14%Cr extruded bars

Science.gov (United States)

Chauhan, A.; Bergner, F.; Etienne, A.; Aktaa, J.; de Carlan, Y.; Heintze, C.; Litvinov, D.; Hernandez-Mayoral, M.; Oñorbe, E.; Radiguet, B.; Ulbricht, A.

2017-11-01

The collaborative study is focused on the relationship between microstructure and yield stress for an ODS Fe-9%Cr-based transformable alloy and an ODS Fe-14%Cr-based ferritic alloy. The contributions to the total room temperature yield stress arising from various strengthening mechanisms are addressed on the basis of a comprehensive description of the microstructures uncovered by means of transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), small-angle neutron scattering (SANS) and atom probe tomography (APT). While these methods provide a high degree of complementarity, a reasonable agreement was found in cases of overlap of information. The derived set of microstructure parameters along with reported strengthening equations was used to calculate the room temperature yield stress. The estimates were critically compared with the measured yield stress for an extended set of alloys including data reported for Fe-Cr model alloys and steels thus covering one order of magnitude or more in grain size, dislocation density, particle density and yield stress. The comparison shows that particle strengthening, dislocation forest strengthening, and Hall-Petch strengthening are the major contributions and that a mixed superposition rule reproduces the measured yield stress within experimental scatter for the whole extended set of alloys. The wide variation of microstructures additionally underpins the conclusions and goes beyond previous work, in which one or few ODS steels and narrow microstructure variations were typically covered.

Low-temperature thermal expansion of metastable intermetallic Fe-Cr phases

International Nuclear Information System (INIS)

Gorbunoff, A.; Levin, A.A.; Meyer, D.C.

2009-01-01

The thermal expansion coefficients (TEC) of metastable disordered intermetallic Fe-Cr phases formed in thin Fe-Cr alloy films prepared by an extremely non-equilibrium method of the pulsed laser deposition are studied. The lattice parameters of the alloys calculated from the low-temperature wide-angle X-ray diffraction (WAXRD) patterns show linear temperature dependencies in the temperature range 143-293 K and a deviation from the linearity at lower temperatures. The linear thermal expansion coefficients determined from the slopes of the linear portions of the temperature-lattice parameter dependencies differ significantly from phase to phase and from the values expected for the body-centered cubic (b.c.c.) Fe 1-x Cr x solid solutions. Strain-crystallite size analysis of the samples is performed. Predictions about the Debye temperature and the mechanical properties of the alloys are made.

Microstructure and Mechanical Properties of n-irradiated Fe-Cr Model Alloys

International Nuclear Information System (INIS)

Matijasevic, Milena; Al Mazouzi, Abderrahim

2008-01-01

High chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems (ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement. In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160 deg. C to 300 deg. C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300 deg. C. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening. (authors)

Nanoindentation of Electropolished FeCrAl Alloy Welds

Energy Technology Data Exchange (ETDEWEB)

Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-13

The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

Optimized Gen-II FeCrAl cladding production in large quantity for campaign testing

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sun, Zhiqian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-06-03

There are two major objectives in this report; (1) to optimize microstructure control of ATF FeCrAl alloys during tube drawing processes, and (2) to provide an update on the progress of ATF FeCrAl tube production via commercial manufacturers. Experimental efforts have been made to optimize the process parameters balancing the tube fabricability, especially for tube drawing processes, and microstructure control of the final tube products. Lab-scale sheet materials of Gen II FeCrAl alloys (Mo-containing and Nb-containing FeCrAl alloys) were used in the study, combined with a stepwise warm-rolling process and intermediate annealing, aiming to simulate the tube drawing process in a commercial tube manufacturer. The intermediate annealing at 650ºC for 1h was suggested for the tube-drawing process of Mo-containing FeCrAl alloys because it successfully softened the material by recovering the work hardening introduced through the rolling step, without inducing grain coarsening due to recrystallization. The final tube product is expected to have stabilized deformed microstructure providing the improved tensile properties with sufficient ductility. Optimization efforts on Nb-containing FeCrAl alloys focused on the effect of alloying additions and annealing conditions on the stability of deformed microstructure. Relationships between the second-phase precipitates (Fe₂Nb-Laves phase) and microstructure stability are discussed. FeCrAl tube production through commercial tube manufacturers is currently in progress. Three different manufacturers, Century Tubes, Inc. (CTI), Rhenium Alloys, Inc. (RAI), and Superior Tube Company, Inc. (STC), are providing capabilities for cold-drawing, warm-drawing, and HPTR cold-pilgering, respectively. The first two companies are currently working on large quantity tube production (expected 250 ft length) of Gen I model FeCrAl alloy (B136Y3, at CTI) and Gen II (C35M4, at RAI), with the process parameters obtained from the experimental

Reduction of Pu(V) and Np(V) by leonardite humic acids and their quinonoid-enriched derivatives

International Nuclear Information System (INIS)

Shcherbina, N.S.; Kalmykov, St.N.; Perminova, I.V.; Kovalenko, A.N.

2005-01-01

Full text of publication follows: Humic substances (HS) are natural poly-electrolytes ubiquitous in aquatic environment responsible for complexation of metal ions. The presence of phenolic and quinonoid moieties in the structure of HS provide for their ability to take part in redox interactions. Capability of HS to reduce plutonium from higher oxidation states (Pu(V) and Pu(VI)) to tetravalent state was reported in several studies. However, the disparate results were reported for Np(V). The contradicting results on the redox behavior of HS could originate from the structural differences of the humic materials tested, in particular, from varying content of the redox-active quinonoid moieties. To test this hypothesis, the goal of this research was to evaluate reducing performance of leonardite humic acids and of their quinonoid-enriched derivatives with respect to Pu(V) and Np(V). The quinonoid-enriched humic derivatives were obtained using the reaction of formaldehyde co-poly-condensation between parent humic material - leonardite humic acid - and model dihydroxybenzenes - hydroquinone, catechol and 1,4-benzoquinone. The humic material: quinonoid monomer ration of 1 g per 250 mg was used. The reduction of Np(V) was studied at micro- and macro-concentration level: 10 -7 M and 10 -4 M, respectively. In case of Pu(V) the concentration was about 10 -10 M. The HS concentrations varied from 1 to 100 ppm, while ionic strength was zero. All experiments were conducted in anaerobic conditions and in the darkness. The kinetics of Pu(V) reduction was studied using solvent extraction (TTA in toluene); to monitor Np(V) reduction two independent techniques were used: solvent extraction and VIS-NIR spectrophotometry. The latter allows measuring absorbance of NpO 2 + and Np-humate complexes at 981.3 and 987.4 nm, respectively. Fast reduction of Pu(V) by the parent humic material was observed and the reduction rate increased with a decrease in pH. In case of Np(V), there was no

Deep Drawing Behavior of CoCrFeMnNi High-Entropy Alloys

Science.gov (United States)

Bae, Jae Wung; Moon, Jongun; Jang, Min Ji; Ahn, Dong-Hyun; Joo, Soo-Hyun; Jung, Jaimyun; Yim, Dami; Kim, Hyoung Seop

2017-09-01

Herein, the deep drawability and deep drawing behavior of an equiatomic CoCrFeMnNi HEA and its microstructure and texture evolution are first studied for future applications. The CoCrFeMnNi HEA is successfully drawn to a limit drawing ratio (LDR) of 2.14, while the planar anisotropy of the drawn cup specimen is negligible. The moderate combination of strain hardening exponent and strain rate sensitivity and the formation of deformation twins in the edge region play important roles in successful deep drawing. In the meanwhile, the texture evolution of CoCrFeMnNi HEA has similarities with conventional fcc metals.

Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

NEUTRON-INDUCED SWELLING OF Fe-Cr BINARY ALLOYS IN FFTF AT ∼400 DEGREES C

International Nuclear Information System (INIS)

Garner, Francis A.; Greenwood, Lawrence R.; Okita, Taira; Sekimura, Naoto; Wolfer, W. G.

2002-01-01

The purpose of this effort is to determine the influence of dpa rate, He/dpa ratio and composition on the void swelling of simple binary Fe-Cr alloys. Contrary to the behavior of swelling of model fcc Fe-Cr-Ni alloys irradiated in the same FFTF-MOTA experiment, model bcc Fe-Cr alloys do not exhibit a dependence of swelling on dpa rate at approximately 400 degrees C. This is surprising in that an apparent flux-sensitivity was observed in an earlier comparative irradiation of Fe-Cr binaries conducted in EBR-II and FFTF. The difference in behavior is ascribed to the higher helium generation rates of Fe-Cr alloys in EBR-II compared to that of FFTF, and also the fact that lower dpa rates in FFTF are accompanied by progressively lower helium generation rates.

Effect of carbon content on solidification behaviors and morphological characteristics of the constituent phases in Cr-Fe-C alloys

International Nuclear Information System (INIS)

Lin, Chi-Ming; Lai, Hsuan-Han; Kuo, Jui-Chao; Wu, Weite

2011-01-01

A combination of transmission electron microscopy, electron backscatter diffraction and wavelength dispersive spectrum has been used to identify crystal structure, grain boundary characteristic and chemical composition of the constituent phases in Cr-Fe-C alloys with three different carbon concentrations. Depending on the three different carbon concentrations, the solidification structures are found to consist of primary α-phase and [α + (Cr,Fe) 23 C 6 ] eutectic in Cr-18.4Fe-2.3 C alloy; primary (Cr,Fe) 23 C 6 and [α + (Cr,Fe) 23 C 6 ] eutectic in Cr-24.5Fe-3.8 C alloy and primary (Cr,Fe) 7 C 3 and [α + (Cr,Fe) 7 C 3 ] eutectic in Cr-21.1Fe-5.9 C alloy, respectively. The grain boundary analysis is useful to understand growth mechanism of the primary phase. The morphologies of primary (Cr,Fe) 23 C 6 and (Cr,Fe) 7 C 3 carbides are faceted structures with polygonal shapes, different from primary α-phase with dendritic shape. The primary (Cr,Fe) 23 C 6 and (Cr,Fe) 7 C 3 carbides with strong texture exist a single crystal structure and contain a slight low angle boundary, resulting in the polygonal growth mechanism. Nevertheless, the primary α-phase with relative random orientation exhibits a polycrystalline structure and comprises a massive high-angle boundary, caused by the dendritic growth mechanism. - Highlights: ► Microstructures of the as-clad Cr-based alloys are characterized by TEM. ► EBSD technique has been use to characterize the grain boundary of primary phases. ► We examine transitions in morphology about the primary phases. ► Morphologies of primary carbides are polygonal different from primary α-phase. ► Solidification structures rely on C concentrations in Cr-Fe-C alloy.

Irradiation of Wrought FeCrAl Tubes in the High Flux Isotope Reactor

Energy Technology Data Exchange (ETDEWEB)

Linton, Kory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Petrie, Christian M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-09-01

The Advanced Fuels Campaign within the Nuclear Technology Research and Development program of the Department of Energy Office of Nuclear Energy is seeking to improve the accident tolerance of light water reactors. Alumina-forming ferritic alloys (e.g., FeCrAl) are one of the leading candidate materials for fuel cladding to replace traditional zirconium alloys because of the superior oxidation resistance of FeCrAl. However, there are still some unresolved questions regarding irradiation effects on the microstructure and mechanical properties of FeCrAl at end-of-life dose levels. In particular, there are concerns related to irradiation-induced embrittlement of FeCrAl alloys due to secondary phase formation. To address this issue, Oak Ridge National Laboratory has developed a new experimental design to irradiate shortened cladding tube specimens with representative 17×17 array pressurized water reactor diameter and thickness in the High Flux Isotope Reactor (HFIR) under relevant temperatures (300–350°C). Post-irradiation examination will include studies of dimensional change, microstructural changes, and mechanical performance. This report briefly summarizes the capsule design concept and the irradiation test matrix for six rabbit capsules. Each rabbit contains two FeCrAl alloy tube specimens. The specimens include Generation I and Generation II FeCrAl alloys with varying processing conditions, Cr concentrations, and minor alloying elements. The rabbits were successfully assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. Pictures of the rabbit assembly process and detailed dimensional inspection of select specimens are included in this report. The rabbits were inserted into HFIR starting in cycle 472 (May 2017).

NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

Energy Technology Data Exchange (ETDEWEB)

Higuchi, Jumpei, E-mail: higuchi@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Sato, Yoichi [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

2011-09-30

NiFe epitaxial films are prepared on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

International Nuclear Information System (INIS)

Higuchi, Jumpei; Ohtake, Mitsuru; Sato, Yoichi; Kirino, Fumiyoshi; Futamoto, Masaaki

2011-01-01

NiFe epitaxial films are prepared on Cr(211) bcc and Cr(100) bcc underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211) bcc and Cr(100) bcc underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

From solid solution to cluster formation of Fe and Cr in α-Zr

International Nuclear Information System (INIS)

Burr, P.A.; Wenman, M.R.; Gault, B.; Moody, M.P.; Ivermark, M.; Rushton, M.J.D.; Preuss, M.; Edwards, L.; Grimes, R.W.

2015-01-01

To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques — atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

From solid solution to cluster formation of Fe and Cr in α-Zr

Energy Technology Data Exchange (ETDEWEB)

Burr, P.A., E-mail: burr.patrick@gmail.com [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Institute of Materials Engineering, Australian Nuclear Science & Technology Organisation, Menai, New South Wales 2234 (Australia); Wenman, M.R. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Gault, B.; Moody, M.P. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Ivermark, M. [High Temperature Materials, Sandvik Materials Technology, 734 27 Hallstahammar (Sweden); University of Manchester, School of Materials, M13 9PL (United Kingdom); Rushton, M.J.D. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Preuss, M. [University of Manchester, School of Materials, M13 9PL (United Kingdom); Edwards, L. [Institute of Materials Engineering, Australian Nuclear Science & Technology Organisation, Menai, New South Wales 2234 (Australia); Grimes, R.W. [Centre for Nuclear Engineering and Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom)

2015-12-15

To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques — atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

Reduced-activation austenitic stainless steels: The Fe--Mn--Cr--C system

International Nuclear Information System (INIS)

Klueh, R.L.; Maziasz, P.J.

1988-01-01

Nickel-free manganese-stabilized steels are being developed for fusion-reactor applications. As the first part of this effort, the austenite-stable region in the Fe--Mn--Cr--C system was determined. Results indicated that the Schaeffler diagram developed for Fe--Ni--Cr--C alloys cannot be used to predict the constituents expected for high-manganese steels. This is true because manganese is not as strong an austenite stabilizer relative to δ-ferrite formation as predicted by the diagram, but it is a stronger austenite stabilizer relative to martensite than predicted. Therefore, the austenite-stable region for Ne--Mn--Cr--C alloys occurs at lower chromium and hugher combinations of manganese and carbon than predicted by the Schaeffler diagram. Development of a manganese-stabilized stainless steel should be possible in the composition range of 20 to 25% Mn, 10 to 15% Cr, and 0.01 to 0.25%C. Tensile behavior of an Fe--20%Mn--12%Cr--0.25%C alloy was determined. The strength and ductility of this possible base composition was comparable to type 316 stainless steel in both the solution-annealed and cold-worked condition

Moessbauer effect study of charge and spin transfer in Fe-Cr

International Nuclear Information System (INIS)

Dubiel, S.M.; Zukrowski, J.

1981-01-01

The influence of temperature and time of annealing on hyperfine fields and isomer shifts has been studied for a range of Fe-Cr alloys containing 1-45 at% Cr. It has been revealed that up to 15 at% Cr neither time or temperature of annealing practically does affect the hyperfine parameters. For more concentrated samples, however, both temperature and time of annealing are important. In particular, the Moessbauer spectrum of Fe-45.5 at% Cr annealed at 700 0 C for 5 h was a single-line indicating that the sample was paramagnetic. The observed changes of the hyperfine fields and the isomer shifts have been interpreted in terms of a spin and charge transfer, respectively. Strong linear correlations between the following quantities have been revealed: the hyperfine field H(0,0) and the isomer shift IS(0,0); the average hyperfine field anti H and the average isomer shift anti Ianti S; the average hyperfine field anti H and the average number of Cr atoms in the first two coordination spheres, anti N. It has been calculated from the first two correlations that a) a change of polarization of itinerant s-like electrons of one electron is equivalent to a change of the hyperfine field of 1602 kOe, and b) on average, a unit change of s-like electron polarization is equivalent to 3277 kOe. The two constants are very close to theoretical estimations, which can be found in literature. Correlation between the hyperfine field and the isomer shift led to a conclusion that the substitution of Fe atoms by Cr ones decreases the density of spin-up electrons on average by 0.026 electrons per one Cr atom in a unit cell. These electrons are most likely trapped by Cr atoms, because the hyperfine field at neighbouring Fe nuclei decreases and the density of charge at those nuclei increases at the rate of 0.029 electrons per one Cr atom in a unit cell. (orig./BHO)

High-temperature oxidation of advanced FeCrNi alloy in steam environments

Science.gov (United States)

Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Rumaiz, Abdul K.; Bai, Jianming; Ghose, Sanjit; Rebak, Raul B.; Ecker, Lynne E.

2017-12-01

Alloys of iron-chromium-nickel are being explored as alternative cladding materials to improve safety margins under severe accident conditions. Our research focuses on non-destructively investigating the oxidation behavior of the FeCrNi alloy "Alloy 33" using synchrotron-based methods. The evolution and structure of oxide layer formed in steam environments were characterized using X-ray diffraction, hard X-ray photoelectron spectroscopy, X-ray fluorescence methods and scanning electron microscopy. Our results demonstrate that a compact and continuous oxide scale was formed consisting of two layers, chromium oxide and spinel phase (FeCr2O4) oxides, wherein the concentration of the FeCr2O4 phase decreased from the surface to the bulk-oxide interface.

Handbook of the Materials Properties of FeCrAl Alloys For Nuclear Power Production Applications

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snead, Mary A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

FeCrAl alloys are a class of alloys that have seen increased interest for nuclear power applications including as accident tolerant fuel cladding, structural components for fast fission reactors, and as first wall and blanket structures for fusion reactors. FeCrAl alloys are under consideration for these applications due to their inherent corrosion resistance, stress corrosion cracking resistance, radiation-induced swelling resistance, and high temperature oxidation resistance. A substantial amount of research effort has been completed to design, develop, and begin commercial scaling of FeCrAl alloys for nuclear power applications over the past half a century. These efforts have led to the development of an extensive database on material properties and process knowledge for FeCrAl alloys but not within a consolidated format. The following report is the first edition of a materials handbook to consolidate the state-of-the-art on FeCrAl alloys for nuclear power applications. This centralized database focuses solely on wrought FeCrAl alloys, oxide dispersion strengthened alloys, although discussed in brief, are not covered. Where appropriate, recommendations for applications of the data is provided and current knowledge gaps are identified.

BISON Fuel Performance Analysis of FeCrAl cladding with updated properties

Energy Technology Data Exchange (ETDEWEB)

Sweet, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, Nathan M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wirth, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-30

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, suitability for normal operation must also be demonstrated. This research is focused on modeling the integral thermo-mechanical performance of FeCrAl-cladded fuel during normal reactor operation. Preliminary analysis has been performed to assess FeCrAl alloys (namely Alkrothal 720 and APMT) as a suitable fuel cladding replacement for Zr-alloys, using the MOOSE-based, finite-element fuel performance code BISON and the best available thermal-mechanical and irradiation-induced constitutive properties. These simulations identify the effects of the mechanical-stress and irradiation response of FeCrAl, and provide a comparison with Zr-alloys. In comparing these clad materials, fuel rods have been simulated for normal reactor operation and simple steady-state operation. Normal reactor operating conditions target the cladding performance over the rod lifetime (~4 cycles) for the highest-power rod in the highest-power fuel assembly under reactor power maneuvering. The power histories and axial temperature profiles input into BISON were generated from a neutronics study on full-core reactivity equivalence for FeCrAl using the 3D full core simulator NESTLE. Evolution of the FeCrAl cladding behavior over time is evaluated by using steady-state operating conditions such as a simple axial power profile, a constant cladding surface temperature, and a constant fuel power history. The fuel rod designs and

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe_3O_4/halloysite nanohybrid

International Nuclear Information System (INIS)

Tian, Xike; Wang, Weiwei; Tian, Na; Zhou, Chaoxin; Yang, Chao; Komarneni, Sridhar

2016-01-01

Highlights: • A novel magnetic nonohybrids (Fe_3O_4/HNTs@C) were synthesized for Cr(VI) removal. • Cr(VI) was reduced to Cr(III) by Fe_3O_4 nanoparticles and hydroxyl groups. • Cr ions were attached on Fe_3O_4/HNTs@C by ion exchange and coordination interaction. - Abstract: In this work, a novel “Dumbbell-like” magnetic Fe_3O_4/Halloysite nanohybrid (Fe_3O_4/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe_3O_4 nanospheres selectively aggregating at the tips of modified halloysite nanotubes was successfully synthesized. XRD, TEM, IR spectroscopy, XPS and VSM were used to characterize this newly halloysite nanohybrid and its formation mechanism was discussed. Cr(VI) ions adsorption experiments showed that the Fe_3O_4/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303 K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe_3O_4 and electron–donor effect of oxygen-containing organic groups, Cr(VI) ions were easily reduced into low toxicity Cr(III) and then adsorbed onto the surface of halloysite nanohybrid. In addition, appreciable magnetization was observed due to the aggregation of magnetite nanoparticles, which make adsorbent facility separated from aqueous solutions after Cr pollution adsorption.

2nd Gen FeCrAl ODS Alloy Development For Accident-Tolerant Fuel Cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Massey, Caleb P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Edmondson, Philip D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

Extensive research at ORNL aims at developing advanced low-Cr high strength FeCrAl alloys for accident tolerant fuel cladding. One task focuses on the fabrication of new low Cr oxide dispersion strengthened (ODS) FeCrAl alloys. The first Fe-12Cr-5Al+Y₂O₃ (+ ZrO₂ or TiO₂) ODS alloys exhibited excellent tensile strength up to 800 C and good oxidation resistance in steam up to 1400 C, but very limited plastic deformation at temperature ranging from room to 800 C. To improve alloy ductility, several fabrication parameters were considered. New Fe-10-12Cr-6Al gas-atomized powders containing 0.15 to 0.5wt% Zr were procured and ball milled for 10h, 20h or 40h with Y2O3. The resulting powder was then extruded at temperature ranging from 900 to 1050 C. Decreasing the ball milling time or increasing the extrusion temperature changed the alloy grain size leading to lower strength but enhanced ductility. Small variations of the Cr, Zr, O and N content did not seem to significantly impact the alloy tensile properties, and, overall, the 2nd gen ODS FeCrAl alloys showed significantly better ductility than the 1st gen alloys. Tube fabrication needed for fuel cladding will require cold or warm working associated with softening heat treatments, work was therefore initiated to assess the effect of these fabrications steps on the alloy microstructure and properties. This report has been submitted as fulfillment of milestone M3FT 16OR020202091 titled, Report on 2nd Gen FeCrAl ODS Alloy Development for the Department of Energy Office of Nuclear Energy, Advanced Fuel Campaign of the Fuel Cycle R&D program.

Interatomic Potential to Simulate Radiation Damage in Fe-Cr Alloys

International Nuclear Information System (INIS)

Bonny, G.; Pasianot, R.; Terentyev, D.; Malerba, L.

2011-01-01

The report presents an Fe-Cr interatomic potential to model high-Cr ferritic alloys. The potential is fitted to thermodynamic and point-defect properties obtained from density functional theory (DFT) calculations and experiments. The developed potential is also benchmarked against other potentials available in literature. It shows particularly good agreement with the DFT obtained mixing enthalpy of the random alloy, the formation energy of intermetallics and experimental excess vibrational entropy and phase diagram. In addition, DFT calculated point-defect properties, both interstitial and substitutional, are well reproduced, as is the screw dislocation core structure. As a first validation of the potential, we study the precipitation hardening of Fe-Cr alloys via static simulations of the interaction between Cr precipitates and screw dislocations. It is concluded that the description of the dislocation core modification near a precipitate might have a significant influence on the interaction mechanisms observed in dynamic simulations.

Interatomic Potential to Simulate Radiation Damage in Fe-Cr Alloys

Energy Technology Data Exchange (ETDEWEB)

Bonny, G.; Pasianot, R.; Terentyev, D.; Malerba, L.

2011-03-15

The report presents an Fe-Cr interatomic potential to model high-Cr ferritic alloys. The potential is fitted to thermodynamic and point-defect properties obtained from density functional theory (DFT) calculations and experiments. The developed potential is also benchmarked against other potentials available in literature. It shows particularly good agreement with the DFT obtained mixing enthalpy of the random alloy, the formation energy of intermetallics and experimental excess vibrational entropy and phase diagram. In addition, DFT calculated point-defect properties, both interstitial and substitutional, are well reproduced, as is the screw dislocation core structure. As a first validation of the potential, we study the precipitation hardening of Fe-Cr alloys via static simulations of the interaction between Cr precipitates and screw dislocations. It is concluded that the description of the dislocation core modification near a precipitate might have a significant influence on the interaction mechanisms observed in dynamic simulations.

Manufacturing of FeCrAl/Zr Dual Layer tube for its application to LWR Fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Jun; Lim, Do Wan; Jung, Yang Il; Kim, Hyun Gil; Park, Jeong Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Many advanced materials such as MAX phases, Mo, SiC, and Fe-based alloys are being considered a possible candidate to substitute the Zr-based alloy cladding has been used in light water reactors. Among the proposed candidate materials, Fe-based alloy is one of the most promising candidates owing to its excellent formability, very good high strength, and corrosion resistance at high temperature. However, neutron cross section of FeCrAl alloy is much higher than that of existing Zr-based alloys. In this study, FeCrAl/Zr dual layer tube was manufactured by using a hot isostatic pressing (HIP) method. The thickness of outer FeCrAl layer was varied from 50 to 250 μm but all the FeCrAl/Zr dual layer tube samples maintained its total thickness of 570 μm. For a detailed microstructural characterization of FeCrAl/Zr dual layer, polarized optical microscopy and scanning electron microscopy (SEM) study carried out and its mechanical property was measured by ring compression test. FeCrAl/Zr dual layer tube sample was successfully manufactured with good adhesion between both layers. Inter layer showing gradual element variation was observed at interface. Result obtained from simulated LOCA test indicates that FeCrAl/Zr dual layer tube may maintain its integrity during LOCA and its accident tolerance had greatly improved compared to that of Zr-based alloy.

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

International Nuclear Information System (INIS)

Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

2016-01-01

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the AlCoFeCr

Activity of Aniline Methylation over Fe-Cu-Cr Ternary Spinel Systems

Directory of Open Access Journals (Sweden)

Reni George

2014-03-01

Full Text Available A series of spinels having thegeneral formula CuCr2-xFexO4 with x=0.25,0.75, 1.25, 1.75 were prepared by co-precipitation method. The catalysts werecharacterized by various physico-chemical methods like XRD, BET, UV-DRS, SEM,EDX, TPD etc. The reaction of aniline with methanol was studied in a fixed-bedreactor system as a potential source for the production of various methylanilines. It was observed that systems possessing low ‘x’ values are highlyselective and active for N-monoalkylation of aniline leading toN-methylaniline. Reaction parameters were properly varied to optimize thereaction conditions for obtaining N-methylaniline selectively and in betteryield. Among the systems CuCr1.75Fe0.25O4 isremarkable due to its very high activity and excellent stability. Under theoptimized conditions N-methylaniline selectivity exceeded 91%. CuCr1.25Fe0.75O4gives better conversion than CuCr1.75Fe0.25O4in CuCr2-xFexO4 series. The Lewis acid sitesof the catalysts are mainly responsible for the good catalytic performance. © 2014 BCREC UNDIP. All rights reservedSubmitted: 18th July 2013; Revised: 5th November 2013; Accepted: 1st December 2013[How to Cite: George, R., George, K., Sugunan, S. (2014. Activity of Aniline Methylation over Fe-Cu-Cr Ternary Spinel Systems. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (1: 39-44. (doi:10.9767/bcrec.9.1.5169.39-44][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.1.5169.39-44] 

Impact of He and Cr on defect accumulation in ion-irradiated ultrahigh-purity Fe(Cr) alloys

DEFF Research Database (Denmark)

Prokhodtseva, A.; Décamps, B.; Ramar, Amuthan

2013-01-01

The effect of He on the primary damage induced by irradiation in ultrahigh-purity (UHP) Fe and Fe(Cr) alloys was investigated by transmission electron microscopy (TEM). Materials were irradiated at room temperature in situ by TEM in a microscope coupled to two ion accelerators, simultaneously pro...

Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys

International Nuclear Information System (INIS)

Moura, L.B.; Guimaraes, R.F.

2010-01-01

The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

Science.gov (United States)

Fabrizi, A.; Timelli, G.

2016-03-01

This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al15(Fe,Mn,Cr)3Si2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al5(Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates.

The Fe-Cr-Zn system in relation with the galvanizing process in chromium-added zinc bath

Energy Technology Data Exchange (ETDEWEB)

Reumont, G.; Mathon, M.; Fourmentin, R.; Perrot, P. [LMPGM, UMR CNRS 8517, Univ. de Lille I, Villeneuve d' Ascq (France)

2003-04-01

Taking into account new experimental measurements, the Fe-Zn-Cr ternary system is critically modified at 460 C. A continuous solid solution between {zeta}-FeZn{sub 13} and CrZn{sub 13} compounds is shown but is shared at 460 C by the stable CrZn{sub 17} compound containing about 2 wt.% Fe. This ternary system is assessed with the CALPHAD method using the PARROT modulus of the Thermo-Calc software. The liquid and solid solution phases are modeled with Redlich-Kister-Muggianu equations. The intermetallic compounds {zeta}-(Fe,Cr)Zn{sub 13} and CrZn{sub 17} are treated as stoichiometric compounds in the binary systems. The experimental Fe and Cr solubilities at various temperatures modify the shape of the liquidus curve and are satisfying for industrial applications. A set of parameters consistent with most of the available experimental data on both phase diagram and solubility measurements is obtained by optimization. A comparison with previous experimental work is also presented and a reactional model between iron substrate and Zn-Cr bath is proposed. This optimization allows to interpret the growth of intermetallic layers and the formation of dross when galvanizing in Cr-added Zn bath. (orig.)

Microstructure of Fe-Cr-C hardfacing alloys with additions of Nb, Ti and, B

International Nuclear Information System (INIS)

Berns, H.; Fischer, A.

1987-01-01

The abrasive wear of machine parts and tools used in the mining, earth moving, and transporting of mineral materials can be lowered by filler wire welding of hardfacing alloys. In this paper, the microstructures of Fe-Cr-C and Fe-Cr-C-Nb/Ti hardfacing alloys and deposits and those of newly developed Fe-Cr-C-B and Fe-Ti-Cr-C-B ones are described. They show up to 85 vol.% of primarily solidified coarse hard phases; i.e., Carbides of MC-, M/sub 7/C/sub 3/-, M/sub 3/C-type and Borides of MB/sub 2/-, M/sub 3/B/sub 2/-, M/sub 2/B-, M/sub 3/B-, M/sub 23/B/sub 6/-type, which are embedded in a hard eutectic. This itself consists of eutectic hard phases and a martensitic or austenitic metal matrix. The newly developed Fe-Cr-C-B alloys reach hardness values of up to 1200 HV and are harder than all purchased ones. The primary solidification of the MB/sub 2/-type phase of titanium requires such high amounts of titanium and boron that these alloys are not practical for manufacture as commercial filler wires

Influence of atomic ordering on sigma phase precipitation of the Fe{sub 50}Cr{sub 50} alloy

Energy Technology Data Exchange (ETDEWEB)

Vélez, G.Y., E-mail: g.y.velezcastillo@gmail.com [Universidad del Valle, Departamento de Física, A.A. 25360 Cali (Colombia); Instituto de Física, Universidad Autónoma de San Luis Potosí, avenida Manuel Nava 6, zona universitaria, 78290 San Luis Potosí, SLP México (Mexico); Pérez Alcázar, G.A. [Universidad del Valle, Departamento de Física, A.A. 25360 Cali (Colombia)

2015-09-25

Highlights: • σ-FeCr phase can be delayed when α-FeCr phase is ordered. • The formation of σ phase is favored by concentration gradients of α phase. • We determine the iron occupation number of the five sites of σ-Fe{sub 50}Cr{sub 50}. - Abstract: In this work we report a study of the kinetic of the formation of the σ-Fe{sub 50}Cr{sub 50} alloy which is obtained by heat treatment of α-FeCr samples with different atomic ordering. Two α-FeCr alloys were obtained, one by mechanical alloying and the other by arc-melting. Both alloys were heated at 925 K for 170 h and then quenched into ice water. Before heat treatment both alloys exhibit α-FeCr disordered structure with greater ferromagnetic behavior in the alloy obtained by mechanical alloying due to its higher atomic disorder. The sigma phase precipitation is influenced by the atomic ordering of the bcc samples: in the alloy obtained by mechanical alloying, the bcc phase is completely transformed into the σ phase; in the alloy obtained by melted the α–σ transformation is partial.

Parametric and experimentally informed BWR Severe Accident Analysis Utilizing FeCrAl - M3FT-17OR020205041

Energy Technology Data Exchange (ETDEWEB)

Ott, Larry J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

Iron-chromium-aluminum (FeCrAl) alloys are being considered as advanced fuel cladding concepts with enhanced accident tolerance. At high temperatures, FeCrAl alloys have slower oxidation kinetics and higher strength compared with zirconium-based alloys. FeCrAl could be used for fuel cladding and spacer or mixing vane grids in light water reactors and/or as channel box material in boiling water reactors (BWRs). There is a need to assess the potential gains afforded by the FeCrAl accident-tolerant-fuel (ATF) concept over the existing zirconium-based materials employed today. To accurately assess the response of FeCrAl alloys under severe accident conditions, a number of FeCrAl properties and characteristics are required. These include thermophysical properties as well as burst characteristics, oxidation kinetics, possible eutectic interactions, and failure temperatures. These properties can vary among different FeCrAl alloys. Oak Ridge National Laboratory has pursued refined values for the oxidation kinetics of the B136Y FeCrAl alloy (Fe-13Cr-6Al wt %). This investigation included oxidation tests with varying heating rates and end-point temperatures in a steam environment. The rate constant for the low-temperature oxidation kinetics was found to be higher than that for the commercial APMT FeCrAl alloy (Fe-21Cr-5Al-3Mo wt %). Compared with APMT, a 5 times higher rate constant best predicted the entire dataset (root mean square deviation). Based on tests following heating rates comparable with those the cladding would experience during a station blackout, the transition to higher oxidation kinetics occurs at approximately 1,500°C. A parametric study varying the low-temperature FeCrAl oxidation kinetics was conducted for a BWR plant using FeCrAl fuel cladding and channel boxes using the MELCOR code. A range of station blackout severe accident scenarios were simulated for a BWR/4 reactor with Mark I containment. Increasing the FeCrAl low-temperature oxidation rate

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

2016-12-15

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

Interdiffusion between Co3O4 coating and the oxide scale of Fe-22Cr alloy

DEFF Research Database (Denmark)

Hansson, Anette Nørgaard; Friehling, Peter B.; Linderoth, Søren

2002-01-01

on Fe-Cr alloys. Coatings of Co3O4 were deposited on a Fe-22Cr alloy by plasma spraying and spray-painting. As-deposited samples were oxidised in air containing 1% H2O at 900C for various exposure time. During exposure the Fe-22Cr alloy forms an oxide scale, which reacts with the coating. The effects...

Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Thompson, Zachary T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-10-01

Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.

The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

International Nuclear Information System (INIS)

Fabrizi, A; Timelli, G

2016-01-01

This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al 15 (Fe,Mn,Cr) 3 Si 2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al 5 (Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates. (paper)

Characteristics Of The Porous Body Sintered By Nano-Sized Fe-Cr-Al Alloy Powder

Directory of Open Access Journals (Sweden)

Lee Su-In

2015-06-01

Full Text Available Porous metal with uniform honeycomb structure was successfully produced by sintering using Fe-Cr-Al nano powder, which was prepared by the pulsed wire evaporation (PWE in ethanol. Its process consisted of the several steps; 1 coating on the surface of polyurethane sponge with the liquid droplets generated from the ethanol-based slurry where the Fe-Cr-Al nano powders were uniformly dispersed, 2 heat treatment of debinding to remove the polyurethane sponge and 3 sintering of the porous green body formed by Fe-Cr-Al nano powders. The strut thickness of porous Fe-Cr-Al was increased by the increase of spraying times in ESP step. Also, The shrinkages and the oxidation resistance of the sintered porous body was increased with increase of sintering temperature. The optimal sintering temperature was shown to 1450°C in views to maximize the oxidation resistance and sinterability.

Phase separation process in FeCr alloys studied by neutron small angle scattering

International Nuclear Information System (INIS)

Furusaka, Michihiro; Ishikawa, Yoshikazu; Yamaguchi, Sadae; Fujino, Yutaka.

1986-01-01

The very early stage as well as late stage of phase separation process in FeCr alloys (Fe-20, 30, 40, 60 at%Cr) have been studied by pulsed cold neutron small angle scattering instrument (SAN). At the early stage, scattering intensity I(q) obeys q -2 dependence at the high q side of the scattering function. The results are in accord with the theory of Langer et al. which takes into account nonlinear and thermal fluctuations effects. At the late stage where I(q) shows q -4 dependence, a dynamical scaling law holds, while it is not the case for the earlier stage. Phase diagram of FeCr system is also determined by critical scattering measurements. (author)

CoCr double-layered media with NiFe and CoZrNb soft-magnetic layers (invited)

International Nuclear Information System (INIS)

Bernards, J.P.C.; Schrauwen, C.P.G.; Zieren, V.; Luitjens, S.B.

1988-01-01

The magnetic, structural, and recording properties of CoCr double-layered media are investigated. The underlayer materials NiFe (crystalline) and CoZrNb (amorphous) were combined with two different kinds of intermediate layers: Ti (crystalline) and Ge (amorphous). Applying a bias voltage during sputtering of NiFe results in a low coercivity of the NiFe layer and in a high coercivity of the CoCr layer. The structure of the NiFe layer influences the structure of the CoCr layer. A Ti layer between the NiFe and CoCr layers decreases the in-plane remanence of the CoCr layer. The coercivity of all CoZrNb layers is low, independent of the application of a bias voltage. The orientation and structure of CoCr on CoZrNb can be improved by using a Ge intermediate layer, which results in a low coercivity of the CoCr. A Ti intermediate layer increases the coercivity. Ring heads show a dependence of spike noise on the underlayer coercivity and on the applied normal force. A probe-type head shows a dependence of its output on the CoCr coercivity, which may be understood in terms of demagnetization and writing depth

Design and characterization of FeCrNiCoAlCu and FeCrNiCo(AlCu){sub 0,5} multicomponent alloys; Previsao e caracterizacao de ligas multicomponentes FeCrNiCoAlCu e FeCrNiCo(AlCu){sub 0,5}

Energy Technology Data Exchange (ETDEWEB)

Triveno Rios, Carlos; Artacho, Victor Falcao [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Engenharia de Materiais

2014-07-01

High entropy alloys using multi-element main quasi-equivalent atomic proportions and generally forms single-phase solid solution and has the ability to enhance levels of strain hardening combined with high levels of plastic deformation at room temperature. In this work two high-entropy alloys with almost similar composition were studied and the factors influencing the formation of solid solution phases (δ atomic radius difference, ΔH{sub mix} mixing enthalpy, ΔS{sub mix} mixing entropy) were evaluated. The microstructure as-cast and the compositions of phases in the two alloys were analyzed by SEM and XRD. The mechanical characterization was realized by measurements of microhardness and cold compression test. The results showed that FeCrNiCo(AlCu){sub 0,5} and FeCrNiCoAlCu alloys with δ equal to 5,7 and 4,9, respectively, form alloys with solid solutions of high entropy. However, the presence of FC and BCCC structures greatly influence the mechanical properties. (author)

The influence of a Cr-dopant on the properties of α-FeOOH particles precipitated in highly alkaline media

International Nuclear Information System (INIS)

Krehula, Stjepko; Music, Svetozar

2009-01-01

The effects of a Cr-dopant on the precipitation of acicular α-FeOOH particles, the formation of solid solutions, particle size and shape were investigated using X-ray powder diffraction (XRD), Moessbauer and Fourier transform infrared (FT-IR) spectroscopies and field emission scanning electron microscopy (FE-SEM). Acicular and monodisperse α-FeOOH particles were precipitated at a very high pH by heating the suspension obtained by adding a tetramethylammonium hydroxide solution to an aqueous solution of FeCl 3 . The influence of the Cr-dopant was investigated by addition of various amounts of Cr 3+ ions to the initial FeCl 3 solution, where r = 100[Cr]/([Cr] + [Fe]) stands for the added amount of Cr. XRD analysis of the obtained powders (with r values from 0 to 23.08) showed only the presence of the diffraction lines characteristic for α-FeOOH. Moessbauer spectroscopy showed a decrease in hyperfine magnetic field of α-FeOOH with an increase in Cr addition which indicates Cr incorporation into the α-FeOOH structure. The OH bending bands in the FT-IR spectra showed only a slight change in position with an increase in r, but the considerable increase in the lattice band wave number indicated a decrease in thickness of the lath-like α-FeOOH particles. This conclusion was confirmed by FE-SEM observations

Change of Cr atoms distribution in Fe85Cr15 alloy caused by 250 keV He+ ion irradiation to different doses

International Nuclear Information System (INIS)

Dubiel, S.M.; Żukrowski, J.

2015-01-01

Highlights: • Effect of He-ion irradiation dose on Fe 85 Cr 15 alloy. • Irradiation-induced clustering of Cr atoms. • Irradiation-caused reorientation of the surface magnetization vector. • Irradiation-caused increase of Fe-site spin-density. - Abstract: Redistribution of Cr atoms in a Fe 85 Cr 15 alloy caused by its irradiation with 250 keV He + ions to different doses, D = 8 ⋅ 10 16 , 16 ⋅ 10 16 and 48 ⋅ 10 16 ions/cm 2 was investigated by means of conversion electrons Mössbauer spectroscopy. The redistribution was expressed in terms of the Warren–Cowley short-range order parameters α 1 , α 2 and α 12 pertaining to the first (1NN), second (2NN) and both i.e. 1NN + 2NN shells, respectively. Clear evidence was found, both for non-irradiated and irradiated samples that the actual distribution of Cr atoms is characteristic of the shell, and for a given shell it depends on the irradiation dose. In particular, α 1 is positive, hence indicates an under population of Cr atoms in 1NN with respect to the random case, α 2 is negative, giving evidence thereby that 2NN is overpopulated by Cr atoms, and α 12 is weakly positive. Under the applied irradiation the number of Cr atoms in both neighbor shells decreased signifying thereby a clustering of Cr atoms. The underlying decrease of Cr concentration within the 1NN–2NN volume around the probe Fe atoms was estimated at 1.5 at.% ranging between 2.1 for the lowest and 0.8 at.% for the highest dose

Ultrafine particles of Ni and FeCr studied by positron annihilation

DEFF Research Database (Denmark)

Eldrup, Morten Mostgaard; Pedersen, N.J.; Sethi, S.A.

1995-01-01

Ultrafine particles of Ni and Fe80Cr20 have been produced by the gas condensation technique. After surface oxidation the paticles were heated in a reducing H2 atmosphere and positron lifetime and Doppler broadening measurements were carried out. Reduction of the oxide on the Ni powder takes place...... at about 350K and at about 650K for the FeCr powder. Electron microscopy shows sintering of the Ni particles above 450K, and the present results show that defects develop in the growing particles....

Creep rupture properties of laves phase strengthened Fe--Ta--Cr--W and Fe--Ta--Cr--W--Mo alloys

International Nuclear Information System (INIS)

Singh, S.

1975-12-01

A small addition of tungsten (0.5 at. percent) was shown to have an effect similar to that of molybdenum on the phase transformation characteristics of alloy Ta7Cr (with a nominal composition of 1 at. percent Ta, 7 at. percent Cr, balance Fe). The existence of time-temperature dependent transformation behavior in alloy Ta7Cr0.5W was confirmed. The effect of spheroidization time and temperature on creep strength was determined. In addition, effect of mechanical processing prior to aging, on creep strength was also determined. It was also shown that by suitable modifications of composition, the grain boundary film can be broken during the aging treatment without the use of spheroidization treatment. Microhardness, tensile and creep properties have been determined. Optical metallography and scanning electron microscopy have been used to follow the microstructural changes and mode of fracture. The creep rupture strength of alloy Ta7CrW alloy was found to be superior to many of the best commercially available ferritic alloys at 1200 0 F. (21 fig., 8 tables)

TSEE from Fe-Cr alloy system and its application to the estimation of gasoline deterioration

International Nuclear Information System (INIS)

Shimada, H.; Nakajima, K.

1983-01-01

The exoelectron glow curves for oxide surface on Fe-Cr alloy were measured as a function of Cr content. It was seen that with increasing Cr content the total counts of thermally stimulated exoelectron emission (TSEE), threshold temperature for measuring the glow curve (starting temperature of the glow curve) and the activation energy clearly indicate a good coincidence with the oxidation process of the surface. The interaction of Fe-Cr alloy with gasoline was examined by applying the test for the oxidation induced period (ASTM D525). The induction period became minimum at about 4%Cr, and the deposit of gasoline gum was maximum at its composition. The results were compared with that of TSEE, and it was found that the catalytic effect of Fe-Cr alloy on the deterioration of gasoline is explained from the starting temperature of the glow curves. (author)

Observation of magnetization and exchange bias reversals in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sharannia, M.P.; De, Santanu [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Singh, Ripandeep; Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Nirmala, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Santhosh, P.N., E-mail: santhosh@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

2017-05-15

Polycrystalline NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} has orthorhombic structure with Pnma space group and is magnetically ordered at room temperature as confirmed by neutron diffraction. The magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} shows magnetization reversal and sign reversal of exchange bias at ~16 K. Nd{sup 3+} moments that get induced by the internal field of |Fe+Cr| sublattice couple antiferromagnetically with the ferromagnetic component of |Fe+Cr| sublattice. Nd{sup 3+} moments overcome the |Fe+Cr| moments at ~16 K below which the material shows negative magnetization and positive exchange bias. - Highlights: • Neutron diffraction confirms magnetic ordering at 300 K in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}. • Magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. • Nd{sup 3+} moments couple antiferromagnetically with |Fe+Cr| ferromagnetic moments. • Shows magnetization reversal and exchange bias reversal.

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

Directory of Open Access Journals (Sweden)

Alvaro A. Rodriguez

2018-01-01

Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

A physics-based crystallographic modeling framework for describing the thermal creep behavior of Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-02

This Report addresses the Milestone M2MS-16LA0501032 of NEAMS Program (“Develop hardening model for FeCrAl cladding), with a deadline of 09/30/2016. Here we report a constitutive law for thermal creep of FeCrAl. This Report adds to and complements the one for Milestone M3MS-16LA0501034 (“Interface hardening models with MOOSE-BISON”), where we presented a hardening law for irradiated FeCrAl. The last component of our polycrystal-based constitutive behavior, namely, an irradiation creep model for FeCrAl, will be developed as part of the FY17 Milestones, and the three regimes will be coupled and interfaced with MOOSE-BISON.

The CrIIL reduction of [2Fe-2S] ferredoxins and site of attachment of CrIII using 1H NMR and site-directed mutagenesis.

Science.gov (United States)

Im, S C; Worrall, J A; Liu, G; Aliverti, A; Zanetti, G; Luchinat, C; Bertini, I; Sykes, A G

2000-04-17

The recently reported NMR solution structure of FeIIIFeIII parsley FdI has made possible 2D NOESY NMR studies to determine the point of attachment of CrIIIL in FeIIIFeIII...CrIIIL. The latter Cr-modified product was obtained by reduction of FeIIIFeIII parsley and spinach FdI forms with [Cr(15-aneN4) (H2O)2]2+ (15-aneN4 = 1,4,8,12-tetraazacyclopentadecane), referred to here as CrIIL, followed by air oxidation and chromatographic purification. From a comparison of NMR cross-peak intensities of native and Cr-modified proteins, two surface sites designated A and B, giving large paramagnetic CrIIIL broadening of a number of amino acid peaks, have been identified. The effects at site A (residues 19-22, 27, and 30) are greater than those at site B (residues 92-94 and 96), which is on the opposite side of the protein. From metal (ICP-AES) and electrospray ionization mass spectrometry (EIMS) analyses on the Cr-modified protein, attachment of a single CrIIIL only is confirmed for both parsley and spinach FdI and FdII proteins. Electrostatic interaction of the 3+ CrIIIL center covalently attached to one protein molecule (charge approximately -18) with a second (like) molecule provides an explanation for the involvement of two regions. Thus for 3-4 mM FeIIIFeIII...CrIIIL solutions used in NMR studies (CrIIIL attached at A), broadening effects due to electrostatic interactions at B on a second molecule are observed. Experiments with the Cys18Ala spinach FdI variant have confirmed that the previously suggested Cys-18 at site A is not the site of CrIIIL attachment. Line broadening at Val-22 of A gives the largest effect, and CrIIIL attachment at one or more adjacent (conserved) acidic residues in this region is indicated. The ability of CrIIL to bind in some (parsley and spinach) but not all cases (Anabaena variabilis) suggests that intramolecular H-bonding of acidic residues at A is relevant. The parsley and spinach FeIIFeIII...CrIIIL products undergo a second stage of reduction

Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe2O6

International Nuclear Information System (INIS)

Batuk, Dmitry; De Dobbelaere, Christopher; Tsirlin, Alexander A.; Abakumov, Artem M.; Hardy, An; Van Bael, Marlies K.; Greenblatt, Martha; Hadermann, Joke

2013-01-01

Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe 2 O 6 is possible by the solution–gel method. • The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr 3+ for Mn 3+ substitution in the BiMnFe 2 O 6 structure. The BiCr x Mn 1−x Fe 2 O 6 solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe 2 O 6 structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R I = 0.036, R P = 0.011) with only a slight decrease in the cell parameters associated with the Cr 3+ for Mn 3+ substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr x Mn 1−x Fe 2 O 6 (x = 0.2; 0.3) and parent BiMnFe 2 O 6 . Only T N slightly decreases upon Cr doping that indicates a very subtle influence of Cr 3+ cations on the magnetic properties at the available substitution rates

Mobility of dislocations in thermal aged and irradiated Fe-Cr alloys

International Nuclear Information System (INIS)

Terentyev, D.; Bonny, G.; Malerba, L.

2007-01-01

Full text of publication follows: The choice of the Cr concentration in reduced-activation ferritic/martensitic steels for fusion applications is largely based on the observed minimum radiation-induced embrittlement, in terms of ductile-to-brittle transition temperature shift (ΔDBTT), found around 9%Cr [1]. To date, no physical explanation for the existence of this minimum has been provided. It is known that in high-Cr ferritic alloys the precipitation of the Cr-rich, coherent α' phase occurs for concentrations above 9% Cr, both due to irradiation or thermal ageing at high enough temperature [2]. The formation of a fine dispersion of precipitates can therefore explain the increased embrittlement above this concentration, but it is unclear why the ΔDBTT should increase also for lower Cr concentrations. In addition, it is suspected that under irradiation a' precipitation may be induced also for Cr contents below 9% [3]. At the same time, it is known that below 9% Cr ferritic alloys exhibit a tendency to ordering, i.e. Cr atoms are not distributed as in a random solid solution and try to be as far apart as possible from each other, thereby tending to create a superlattice [4]. In order to cast some light on the effect that these phase changes may have on dislocation motion in the presence of radiation damage, we study at the atomic level the mobility of dislocations in FeCr alloys of different concentrations where Cr is distributed in different fashions (i.e. ordered, clustered or in a random solid solution) and in the presence of radiation damage (e.g. point-defect clusters created by cascades). The microstructure will be obtained by making the system evolve according to the acting thermodynamic driving forces (also in the presence of defects) using Metropolis Monte Carlo techniques. Subsequently, the simulation of the dislocation motion will be performed using large scale molecular dynamics, whereby the corresponding stress-strain curve can be obtained. The

A study on martensitic structure in Fe-4Cr-0.4C steel

International Nuclear Information System (INIS)

Won, S.B.

1980-01-01

Morphology, dependence of prior austenite grain size and packet size upon austenitizing temperature, distribution of lath width, and habit plane of martensitic structure in Fe-4Cr-0.4C steel has been studied by optical microscopy and transmission electron microscopy. The results obtained are as follows. 1) Optical microstructures of martensitic Fe-4Cr-0.4C steel consist of lath martensite and lens martensite. Also the four types of morphology are observed by electron microscopy. The most common morphologies are a regular paralleled martensite and an irregular dovetailed lath martensite, while the remainder of microstructures consists mainly of groups of internally twinned martensite and autotempered laths. 2) Prior austenite grain size and packet size increased with austenizing temperature, and also the numbers of lath contained in a prior austenite grain or a packet are increased with austenizing temperature. 3) The mean width of lath in Fe-4Cr-0.4C steel is about 0.23μm and most of lath widths are below 0.5μm. 4) Martensite habit plane of Fe-4Cr-0.4C steel is nearly [110]α'. (author)

Antibacterial Effect of CrO and CoFe2O4 Nanoparticles upon Staphylococcus aureus

Directory of Open Access Journals (Sweden)

Saber Imani

2011-12-01

Full Text Available Background & Objectives: The use of metal oxide nanoparticles can be effective to eliminate the bacterial infections, as an alternative to antibiotics. In this study, antibacterial properties of nonmaterials of CrO and CoFe2O4 are investigated against Staphylococcus aureus as a major and prevalent pathogenic bacterium to achieve sterile nano-containers. Materials & Methods: Different concentrations of CrO and CoFe2O4 nanoparticles, (0.2, 0.4, 0.6, 0.8, and 1% of each, were examined with respect to their optical density (OD culture separately. Different percentages of each nanoparticles were also examined together for the best antibacterial combination. Kinetics of Bactericidal of nanoparticles were calculated in two-hour periods and were compared with the power of other common antibiotics. Ratios of MIC/MBC were calculated by Micro dilution method, to demonstrate the bactericidal power of nanoparticles. Results: The best concentration of the nanoparticles with the highest effect of bactericidal was obtained in the presence of 1% concentration of CrO that the OD of S. aureus culture medium had reduced 4/6 times than the control group (p<0/001.Ratio of 70% CrO to 30% CoFe2O4 was the best of the Bacteriostatic properties that OD was reduced 3/3 times than the control group (p<0/05. Best kinetics of bactericidal with survival rate in the presence of 1% CrO and CoFe2O4 were obtained in 24 and 36 hours respectively. In critical concentration of 1% CrO and CoFe2O4 bactericidal power was about 67 and 56 % respectively. The MIC/MBC rate for CrO and CoFe2O4 was obtained 0/2 and 0/4 respectively. Conclusion: The results showed that CrO nanoparticle compared with CoFe2O4 has a higher bactericidal power for S. aureus infection. Therefore, by completion of these experiments and the use of metal oxide nanoparticles complex in sensitive environments such as food storage containers, etc. are suggested.

Method of simultaneous continuous determination of transfer rates of iron and chromium into solution during Fe-Cr alloys dissolution

International Nuclear Information System (INIS)

Shirinov, T.I.; Florianovich, G.M.; Skuratnik, Ya.B.

1978-01-01

Radiometry method of simultaneous continuous registration of transfer rates of iron and chromium into solution from Fe-Cr alloys with various composition has been developed. Using gamma-spectrometer components of Fe-Cr alloys can be determined with high sensitivity in separate samples according to Fe 59 and Cr 51 radioactive labels, obtained by neutron activation. The above method is applied to estimate Fe and Cr transfer rates into H 2 SO 4 solution at the temperature of 50 deg from Fe - 28% Cr alloy during its active dissolution. It is established, that beginning with some seconds of alloy and solution contact, its components transfer into the solution in the same composition, as in the alloy. The method enables to determine Fe with the accuracy of up to 5% and Cr with that of up to 10%

Correlative Microscopy of Alpha Prime Precipitation in Neutron-Irradiated Fe-Cr-Al Alloys

Energy Technology Data Exchange (ETDEWEB)

Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States)

2016-12-01

Fe-Cr-Al alloys are currently being considered for accident tolerant light water reactor fuel cladding applications due to their superior high temperature oxidation and corrosion resistance compared to Zr-based alloys. This work represents the current state-of-the-art on both techniques for analysis of α' precipitate microstructures and the processes and mechanisms governing its formation in neutron-irradiated Fe-Cr-Al alloys.

Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

Science.gov (United States)

Guo, Jun; Huang, Xuefei; Huang, Weigang

2017-07-01

FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

Science.gov (United States)

Muralidharan, Govindarajan

2017-09-05

An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

Fabrication of core-shell Fe{sub 3}O{sub 4}@MIL-100(Fe) magnetic microspheres for the removal of Cr(VI) in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Yang, Qingxiang, E-mail: qxyangzz@163.com; Zhao, Qianqian; Ren, ShuangShuang; Lu, Qiongqiong; Guo, Xinmeng; Chen, Zhijun, E-mail: chenzj@zzuli.edu.cn

2016-12-15

Facile regeneration of an adsorbent is very important for commercial feasibility. One typical highly porous metal-organic framework (MOF) materials based on MIL-100(Fe) and magnetic iron oxide particles (denoted as MMCs) with diameter about of 350 nm were successfully synthesized. The growth of MIL-100(Fe) shell on the surface of Fe{sub 3}O{sub 4} was utilized precursor as crystal seed via in-situ step hydrothermal reaction. It is a simple way to obtain well organized core-shell MOF composites, compared to the step-by-step method. MMCs were firstly used to uptake of Cr(VI) anions in aqueous solution. Adsorption experiments were carried out in batch sorption mode investigating with the factors of contact time (0–1000 min), pH (from 2 to 12), dose of adsorbent (4–25 mg), and initial Cr(VI) concentration (range from 10 to 100 ppm). - Graphical abstract: One typical highly porous metal-organic framework (MOF) materials based on MIL-100(Fe) and magnetic iron oxide particles (denoted as MMCs) were successfully synthesized. Utilizing Fe{sub 3}O{sub 4} precursor as crystal seed to grow MIL-100(Fe) shell by in-situ step hydrothermal reaction. It is a simple way to obtain core-shell MOF composites. MMCs could effectively uptake of Cr(VI) anions in aqueous solution. - Highlights: • Fe{sub 3}O{sub 4}@MIL-100(Fe) composites with core-shell structure were successfully prepared through a simple method. • The influence factors on Cr(VI) adsorption by Fe{sub 3}O{sub 4}@MIL-100(Fe) were investigated. • Cr(VI) can efficiently adsorbed by Fe{sub 3}O{sub 4}@MIL-100(Fe) composites from aqueous solution.

On the passivation mechanism of Fe{sub 3}O{sub 4} nanoparticles during Cr(VI) removal from water: A XAFS study

Energy Technology Data Exchange (ETDEWEB)

Pinakidou, F., E-mail: fpina@physics.auth.gr [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, M. [Aristotle University of Thessaloniki, School of Physics, Section of Solid State Physics, 54124 Thessaloniki (Greece); Simeonidis, K.; Kaprara, E. [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Paloura, E.C. [Aristotle University of Thessaloniki, School of Physics, Section of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, M. [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

2016-01-01

Graphical abstract: - Highlights: • Presence of Fe(II) even after high Cr-loading. • The vacancies in the γ-Fe{sub 2}O{sub 3} layer formed offer sites for Cr(III) sorption. • Cr(III) sorbs into the vacancies and Cr(VI) forms outer sphere complexes. • Increasing surface Cr(III) loading changes the polymerization of the Fe–O–Fe chains. • Cr(III) sorption modifies Fe{sub 3}O{sub 4} structure obstructing further Cr(VI) removal. - Abstract: X-Ray Absorption Spectroscopies (XAFS) are employed in order to gather a thorough insight on the uptake mechanism of Cr(VI) by Fe{sub 3}O{sub 4} nanoparticles under water treatment conditions. The XANES measurements identify that the reducing potential of Fe{sub 3}O{sub 4} activates the precipitation of Cr(VI) in the form of insoluble and non-toxic Cr(III). However, electron donation from Fe(II) is responsible for its gradual consumption, resulting in the presence of a surface maghemite layer and the formation of structural vacancies. EXAFS analysis reveal that adsorption of Cr(III)-oxyanions occurs on sorption sites provided by the vacancies in the maghemite layer, where Cr(III) is involved in a bidentate binuclear ({sup 2}E) geometry with Fe-octahedra while it also forms monodentate ({sup 1}V) complexes with the Fe(III)O{sub 4} tetrahedra. The surface maghemitization along with the reduced Cr(III) adsorption into the vacancies, tracks the degree of Cr-reduction, since this surface structural modifications hinder Cr(VI) access to the Fe(II) ions of the magnetite nanoparticles. Thus, high surface coverage leads to the passivation of the reduction ability since physisorbed Cr(VI) is also detected through the formation of outer sphere complexes.

Ab initio based kinetic Monte-Carlo simulations of phase transformations in FeCrAl

International Nuclear Information System (INIS)

Olsson, Paer

2015-01-01

Document available in abstract form only, full text follows: Corrosion and erosion in lead cooled reactors can be a serious issue due to the high operating temperature and the necessary flow rates. FeCrAl alloys are under consideration as cladding or as coating for stainless steel cladding tubes for lead cooled reactor concepts. The alumina scale that is formed, as Al segregates to the surface and Fe and Cr rich oxides break off, offers a highly protective layer against lead corrosion in a large range of temperatures. However, there are concerns about the phase stability of the alloy under irradiation conditions and of possible induced alpha-prime precipitation. Here a theoretical model of the ternary FeCrAl alloy is presented, based on density functional theory predictions and linked to a kinetic Monte-Carlo simulation framework. The effect of Al on the FeCr miscibility properties are discussed and the coupling of irradiation induced defects with the solutes are treated. Simulations of the micro-structure evolution are tentatively compared to available experiments. (authors)

High-resolution electron microscopy study of Ni81Fe19 film with Co33Cr67 buffer layer

International Nuclear Information System (INIS)

Xu, Q.Y.; Wang, Z.M.; Shen, F.; Du, Y.W.; Zhang, Z.

2003-01-01

The anisotropic magnetoresistance (AMR) in permalloy Ni 81 Fe 19 film deposited on a 1.2 nm Co 33 Cr 67 buffer layer was significantly enhanced. The high-resolution electron microscopy was used to study the microstructure of Ni 81 Fe 19 film with and without Co 33 Cr 67 buffer layer. It was found that Co 33 Cr 67 buffer layer can induce good (1 1 1) texture, while without Co 33 Cr 67 buffer layer, Ni 81 Fe 19 film show randomly oriented grain structure. The Δρ/ρ enhancement is attributed to the decrease in the resistivity ρ of the Ni 81 Fe 19 film due to the formation of the large (1 1 1) textured grains in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer. However, the surface roughness of substrate may limit the (1 1 1) textured grain size and induce additional grain boundaries in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer, limit the enhancement of the AMR effect

Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas

Science.gov (United States)

Feldman, U.; Doschek, G. A.; Cheng, C.-C.; Bhatia, A. K.

1980-01-01

The paper considers the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. Tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences are presented, and collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence are given. Similarities of tokamak and solar spectra are discussed, and it is shown how the atomic data presented may be used to determine ion abundances and electron densities in low-density plasmas.

Solubility of sulfur in Fe-Cr-Ni alloys

International Nuclear Information System (INIS)

Bogolyubskij, S.D.; Petrova, E.F.; Rogov, A.I.; Shvartsman, L.A.

1979-01-01

The solubility of 35 S was determined in Fe-Cr-Ni alloys in the range of temperatures between 910 and 1050 deg C by the method of radiometric analysis. It was found that the solubility of sulfur increases with the concentration of chromium in alloys with 20% Ni

Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

Science.gov (United States)

Chaudhary, V.; Ramanujan, R. V.

2016-10-01

Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100-xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg-1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe{sub 3}O{sub 4}/halloysite nanohybrid

Energy Technology Data Exchange (ETDEWEB)

Tian, Xike, E-mail: xktian@cug.edu.cn [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Wang, Weiwei; Tian, Na; Zhou, Chaoxin; Yang, Chao [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Komarneni, Sridhar [Materials Research Laboratory, Materials Research Institute and Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16802 (United States)

2016-05-15

Highlights: • A novel magnetic nonohybrids (Fe{sub 3}O{sub 4}/HNTs@C) were synthesized for Cr(VI) removal. • Cr(VI) was reduced to Cr(III) by Fe{sub 3}O{sub 4} nanoparticles and hydroxyl groups. • Cr ions were attached on Fe{sub 3}O{sub 4}/HNTs@C by ion exchange and coordination interaction. - Abstract: In this work, a novel “Dumbbell-like” magnetic Fe{sub 3}O{sub 4}/Halloysite nanohybrid (Fe{sub 3}O{sub 4}/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe{sub 3}O{sub 4} nanospheres selectively aggregating at the tips of modified halloysite nanotubes was successfully synthesized. XRD, TEM, IR spectroscopy, XPS and VSM were used to characterize this newly halloysite nanohybrid and its formation mechanism was discussed. Cr(VI) ions adsorption experiments showed that the Fe{sub 3}O{sub 4}/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303 K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe{sub 3}O{sub 4} and electron–donor effect of oxygen-containing organic groups, Cr(VI) ions were easily reduced into low toxicity Cr(III) and then adsorbed onto the surface of halloysite nanohybrid. In addition, appreciable magnetization was observed due to the aggregation of magnetite nanoparticles, which make adsorbent facility separated from aqueous solutions after Cr pollution adsorption.

Effects of Cr underlayer and Pt buffer layer on the interfacial structure and magnetic characteristics of sputtered FePt films

International Nuclear Information System (INIS)

Sun, A.-C.; Hsu, J.-H.; Huang, H.L.; Kuo, P.C.

2006-01-01

This work develops a new method for growing L1 0 FePt(0 0 1) thin film on a Pt/Cr bilayer using an amorphous glass substrate. Semi-coherent epitaxial growth was initiated from the Cr(0 0 2) underlayer, continued through the Pt(0 0 1) buffer layer, and extended into the L1 0 FePt(0 0 1) magnetic layer. The squareness of the L1 0 FePt film in the presence of both a Cr underlayer and a Pt buffer layer was close to unity as the magnetic field was applied perpendicular to the film plane. The single L1 0 FePt(1 1 1) orientation was observed in the absence of a Cr underlayer. When a Cr underlayer is inserted, the preferred orientation switched from L1 0 FePt(1 1 1) to L1 0 FePt(0 0 1) and the magnetic film exhibited perpendicular magnetic anisotropy. However, in the absence of an Pt intermediate layer, the Cr atoms diffused directly into the FePt magnetic layer and prevented the formation of the L1 0 FePt(0 0 1) preferred orientation. When a Pt buffer layer was introduced between the FePt and Cr underlayer, the L1 0 FePt(0 0 1) peak appeared. The thickness of the Pt buffer layer also substantially affected the magnetic properties and atomic arrangement at the FePt/Pt and Pt/Cr interfaces

Uptake of CrO42- ions by Fe-treated tri-calcium phosphate

International Nuclear Information System (INIS)

Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E.

2010-01-01

CrO 4 2- ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10 -4 M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO 4 2- ions was 7.10 x 10 -3 mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters ΔH 0 , ΔG 0 and ΔS 0 were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

FeCrAl/Zr dual layer fuel cladding for improved safety margin under accident scenario

International Nuclear Information System (INIS)

Park, D.J.; Park, J.H.; Jung, Y.I.; Kim, H.G.; Park, J.Y.; Koo, Y.H.

2014-01-01

For application of advanced steel as a cladding material in light water reactor (LWR), FeCrAl/Zr dual layer tube was manufactured by using a hot isostatic pressing (HIP) method. To optimize HIP condition for joining both FeCrAl and Zr alloys, HIP was carried out under various temperature conditions. Tensile test and 3-point bend test performed for measuring mechanical properties of HIPed sample. To better understand microstructural characteristics in interface region between two alloys, SEM and TEM study were conducted by using HIPed sample with different process conditions. Based on this optimization study and analyzed results, optimized HIP condition was determined and FeCrAl/Zr dual layer fuel cladding having same wall thickness with current LWR fuel cladding was manufactured. Simulated loss-of-coolant accident test was carried out using FeCrAl/Zr dual layer cladding sample and fuel integrity was measured by mechanical test. (authors)

Microstructure and Hot Deformation Behavior of Fe-20Cr-5Al Alloy

OpenAIRE

Jung-Ho Moon; Tae Kwon Ha

2014-01-01

High temperature deformation behavior of cast Fe-20Cr-5Al alloy has been investigated in this study by performing tensile and compression tests at temperatures from 1100 to 1200oC. Rectangular ingots of which the dimensions were 300×300×100 in millimeter were cast using vacuum induction melting. Phase equilibrium was calculated using the FactSage®, thermodynamic software and database. Tensile strength of cast Fe-20Cr-5Al alloy was 4 MPa at 1200oC. With temperature decreas...

First-principle study of structural, electronic, vibrational and magnetic properties of HCN adsorbed graphene doped with Cr, Mn and Fe

International Nuclear Information System (INIS)

Shi, Li Bin; Wang, Yong Ping; Dong, Hai Kuan

2015-01-01

Graphical abstract: - Highlights: • Cr, Mn and Fe doped graphene is more active to adsorb HCN molecule than pristine graphene. • The conductivity of Fe and Mn doped graphene hardly changes after adsorption HCN molecule. • The conductivity of Cr doped graphene can be affected significantly due to HCN adsorption. • The Cr, Mn and Fe may destroy the long range order in graphene. • Phonon density of states suggests that Cr doped graphene is stable. - Abstract: The adsorption energy, electronic structure, lattice vibration and magnetic properties of Cr, Mn and Fe doped graphene with and without HCN adsorption are investigated by the first principles based on density functional theory. The physisorption and chemisorption have been identified. In the paper, Cr-NG, Mn-NG and Fe-NG denote HCN adsorption on Cr, Mn and Fe doped graphene with N atom toward the adsorption site. It is found that the adsorption energy is −1.36 eV for Fe-NG, −0.60 eV for Mn-NG and −0.86 eV for Cr-NG. The Cr-NG will convert from half-metallic behavior to semiconductor after adsorbing HCN molecule, which indicates that the conductivity changes significantly. Phonon density of states (PDOS) shows that the long range order in graphene can be destroyed by doping Fe, Mn and Cr. The imaginary frequency mode in PDOS suggests that Fe and Mn doped graphene is unstable, while Cr doped graphene is stable. The electronic properties are sensitive toward adsorbing HCN, indicating that Cr doped graphene is a promising sensor for detecting HCN molecule. This study provides a useful basis for understanding of a wide variety of physical properties on graphene

Synthesis and characterization of La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Fabian, F.A., E-mail: fernandafabianro@gmail.com [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Pedra, P.P.; Filho, J.L.S. [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Duque, J.G.S.; Meneses, C.T. [Universidade Federal de Sergipe, Campus Prof. Alberto Carvalho, Departamento de Física, 49500-000 Itabaiana, SE (Brazil)

2015-04-01

Magnetic and structural properties have been investigated in La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method. The X-ray diffraction measurements allied to Rietveld method confirm the formation of LaCrO{sub 3}, LaFeO{sub 3} and LaMnO{sub 3} nanoparticles with crystal structure orthorhombic (Pbnm), orthorhombic (Pnma) and rhombohedral (R-3c), respectively. We also verified an decreasing in the average crystallite size from 73 to 26 nm, depending of the transition metal. The magnetic measurements reveal an antiferromagnetic behavior for the LaCrO{sub 3} sample with T{sub N}~289 K, and a weak ferromagnetic ordering for the LaMnO{sub 3} sample with T{sub c}~200 K. - Highlights: • La(Cr,Fe,Mn)O{sub 3} nanoparticles were synthesized by coprecipitation method. • XRD results confirm the formation single phase in the compounds studied. • Magnetic property in the La(Fe,Cr,Mn)O{sub 3} nanoparticles dependent on the TM. • La(Cr,Fe)O{sub 3} nanoparticles presented behavior antiferromagnetic and LaMnO{sub 3} ferromagnetic.

Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

International Nuclear Information System (INIS)

Sungkono; Siti Aidah

2015-01-01

Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

TEM/STEM study of Zircaloy-2 with protective FeAl(Cr) layers under simulated BWR environment and high-temperature steam exposure

Science.gov (United States)

Park, Donghee; Mouche, Peter A.; Zhong, Weicheng; Mandapaka, Kiran K.; Was, Gary S.; Heuser, Brent J.

2018-04-01

FeAl(Cr) thin-film depositions on Zircaloy-2 were studied using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) with respect to oxidation behavior under simulated boiling water reactor (BWR) conditions and high-temperature steam. Columnar grains of FeAl with Cr in solid solution were formed on Zircaloy-2 coupons using magnetron sputtering. NiFe2O4 precipitates on the surface of the FeAl(Cr) coatings were observed after the sample was exposed to the simulated BWR environment. High-temperature steam exposure resulted in grain growth and consumption of the FeAl(Cr) layer, but no delamination at the interface. Outward Al diffusion from the FeAl(Cr) layer occurred during high-temperature steam exposure (700 °C for 3.6 h) to form a 100-nm-thick alumina oxide layer, which was effective in mitigating oxidation of the Zircaloy-2 coupons. Zr intermetallic precipitates formed near the FeAl(Cr) layer due to the inward diffusion of Fe and Al. The counterflow of vacancies in response to the Al and Fe diffusion led to porosity within the FeAl(Cr) layer.

Fuel Performance Calculations for FeCrAl Cladding in BWRs

Energy Technology Data Exchange (ETDEWEB)

George, Nathan [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Sweet, Ryan [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Maldonado, G. Ivan [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Wirth, Brian D. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Powers, Jeffrey J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Worrall, Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-01-01

This study expands upon previous neutronics analyses of the reactivity impact of alternate cladding concepts in boiling water reactor (BWR) cores and directs focus toward contrasting fuel performance characteristics of FeCrAl cladding against those of traditional Zircaloy. Using neutronics results from a modern version of the 3D nodal simulator NESTLE, linear power histories were generated and supplied to the BISON-CASL code for fuel performance evaluations. BISON-CASL (formerly Peregrine) expands on material libraries implemented in the BISON fuel performance code and the MOOSE framework by providing proprietary material data. By creating material libraries for Zircaloy and FeCrAl cladding, the thermomechanical behavior of the fuel rod (e.g., strains, centerline fuel temperature, and time to gap closure) were investigated and contrasted.

Pressure effects on spin density wave in Cr rich Cr-Al, Si, Mn, Fe and Co alloys

International Nuclear Information System (INIS)

Mizuki, Jun-ichiro; Endoh, Yasuo; Ishikawa, Yoshikazu

1982-01-01

The effect of pressure on the spin density wave (SDW) state in Cr rich Cr-Al, Si, Nn, Fe and Co alloys has been elucidated by neutron diffraction studies. We found that the change of the SDW wave vector Q, by applying pressure, 1/Q. delta Q/ delta P, is linearly related to the decrease of T sub(N) with increasing pressure 1/T sub(N). delta T sub(N)/ delta P and that all the results from the Cr-Si, Fe and Co alloys fall on a single straight line independent of their concentrations. Their magnetic phase diagrams in a temperature-pressure coordinate system can be related to the alloy phase diagram by employing an empirical rule that applying pressure corresponds to a decrese in the electron to atom ratio. The non transition metal Si impurity has been found to act as an electron donor, while the effect of Al is not interpreted by the two band nesting model. (author)

Nanostructured Fe-Cr Alloys for Advanced Nuclear Energy Applications

Energy Technology Data Exchange (ETDEWEB)

Scattergood, Ronald O. [North Carolina State Univ., Raleigh, NC (United States)

2016-04-26

We have completed research on the grain-size stabilization of model nanostructured Fe14Cr base alloys at high temperatures by the addition of non-equilibrium solutes. Fe14Cr base alloys are representative for nuclear reactor applications. The neutron flux in a nuclear reactor will generate He atoms that coalesce to form He bubbles. These can lead to premature failure of the reactor components, limiting their lifetime and increasing the cost and capacity for power generation. In order to mitigate such failures, Fe14Cr base alloys have been processed to contain very small nano-size oxide particles (less than 10 nm in size) that trap He atoms and reduce bubble formation. Theoretical and experimental results indicate that the grain boundaries can also be very effective traps for He atoms and bubble formation. An optimum grain size will be less than 100 nm, ie., nanocrystalline alloys must be used. Powder metallurgy methods based on high-energy ball milling can produce Fe-Cr base nanocrystalline alloys that are suitable for nuclear energy applications. The problem with nanocrystalline alloys is that excess grain-boundary energy will cause grains to grow at higher temperatures and their propensity for He trapping will be lost. The nano-size oxide particles in current generation nuclear alloys provide some grain size stabilization by reducing grain-boundary mobility (Zener pinning – a kinetic effect). However the current mitigation strategy minimizing bubble formation is based primarily on He trapping by nano-size oxide particles. An alternate approach to nanoscale grain size stabilization has been proposed. This is based on the addition of small amounts of atoms that are large compared to the base alloy. At higher temperatures these will diffuse to the grain boundaries and will produce an equilibrium state for the grain size at higher temperatures (thermodynamic stabilization – an equilibrium effect). This would be preferred compared to a kinetic effect, which is not

Ring head recording on perpendicular media: Output spectra for CoCr and CoCr/NiFe media

Science.gov (United States)

Stubbs, D. P.; Whisler, J. W.; Moe, C. D.; Skorjanec, J.

1985-04-01

The recording density response for sputtered CoCr (thickness=0.5 μm) and CoCr/NiFe (t=0.25 μm/0.5 μm) as well as evaporated CoNi (t=0.12 μm) and Co surface-doped iron oxide particulate media has been measured by reading and writing with Mn-Zn ferrite heads (gap length=0.375 μm, track width=37 μm) in contact with the media. Measurements to 200 kfc/i (thousand flux changes per inch) show a gap null around 115 kfc/i. The data have been normalized by dividing out the head sensitivity to obtain the value of spacing plus transition width (d+a) for the various media. For the CoCr media this value varied from 0.075-0.088 μm; for CoNi, 0.100 μm, and for the particulate medium, 0.163 μm. In addition, testing with a larger gapped Mn-Zn ferrite head (g=2.43 μm) shows that the head fields are distorted by the soft magnetic underlayer in dual layer CoCr/NiFe samples when the gap length is large compared to the distance to the underlayer.

Electronic configuration of nFe/3Cr/nFe (n=1-6) trilayers in FM state

International Nuclear Information System (INIS)

Botana, J.; Pereiro, M.; Baldomir, D.; Arias, J.E.; Warda, K.; Wojtczak, L.

2007-01-01

Ab initio calculations have been performed on several ultrathin Fe/Cr/Fe trilayer systems in ferromagnetic configuration, with a fixed width of the spacer chromium slab of three atomic monolayers, and both iron slabs symmetrically varying in a range from 1 to 6 atomic monolayers. We have calculated the charge distribution of these trilayers and calculated and plotted the density of states of every one of them. We have identified Friedel-like oscillations of the charge distribution from the Mulliken population analysis in the Fe slabs

Investigation of the thermo-mechanical behavior of neutron-irradiated Fe-Cr alloys by self-consistent plasticity theory

Energy Technology Data Exchange (ETDEWEB)

Xiao, Xiazi [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, BIC-ESAT, Peking University, Beijing 100871 (China); Terentyev, Dmitry [Structural Material Group, Institute of Nuclear Materials Science, SCK CEN, Mol (Belgium); Yu, Long [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); Bakaev, A. [Structural Material Group, Institute of Nuclear Materials Science, SCK CEN, Mol (Belgium); Jin, Zhaohui [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Duan, Huiling, E-mail: hlduan@pku.edu.cn [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, BIC-ESAT, Peking University, Beijing 100871 (China)

2016-08-15

The thermo-mechanical behavior of non-irradiated (at 223 K, 302 K and 573 K) and neutron irradiated (at 573 K) Fe-2.5Cr, Fe-5Cr and Fe-9Cr alloys is studied by a self-consistent plasticity theory, which consists of constitutive equations describing the contribution of radiation defects at grain level, and the elastic-viscoplastic self-consistent method to obtain polycrystalline behaviors. Attention is paid to two types of radiation-induced defects: interstitial dislocation loops and solute rich clusters, which are believed to be the main sources of hardening in Fe-Cr alloys at medium irradiation doses. Both the hardening mechanism and microstructural evolution are investigated by using available experimental data on microstructures, and implementing hardening rules derived from atomistic data. Good agreement with experimental data is achieved for both the yield stress and strain hardening of non-irradiated and irradiated Fe-Cr alloys by treating dislocation loops as strong thermally activated obstacles and solute rich clusters as weak shearable ones. - Highlights: • A self-consistent plasticity theory is proposed for irradiated Fe-Cr alloys. • Both the irradiation-induced hardening and plastic flow evolution are studied. • Dislocation loops and solute rich clusters are considered as the main defects. • Numerical results of the proposed model match with corresponding experimental data.

A preparation method and effects of Al–Cr coating on NdFeB sintered magnets

International Nuclear Information System (INIS)

Zheng, Jingwu; Lin, Min; Xia, Qingping

2012-01-01

A 50 μm Al–Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 °C. The morphology and composition of the Al–Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al–Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al–Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al–Cr coating moves positively from −0.67 to −0.48 V, which is in accordance with Nyquist and Bode plots. The Al–Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: ► The Al–Cr coating can be prepared by dipping in solution, shaking dry and heating. ► The coating morphology shows to be an intense overlapping structure. ► The barrier effect combines with passivation and cathodic protection. ► The anticorrosion abilities improve while magnetic properties change little. ► Compared with other surface treatments, this method is convenient and low cost.

Structural and Giant Magneto-impedance properties of Cr-incorporated Co-Fe-Si-B amorphous microwires

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Partha [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Basu Mallick, A. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Roy, R.K. [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Panda, A.K., E-mail: akpanda@nmlindia.org [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mitra, A. [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)

2012-04-15

The investigation is focused on the effect of Cr incorporation for Co/Fe in (Co{sub 0.5}Fe{sub 0.5}){sub 78-x}Cr{sub x}Si{sub 8}B{sub 14} (x=0-12) amorphous microwires of 110 {mu}m diameter prepared by in-water quenching technique. The rise in crystallization onset T{sub X1} with Cr addition revealed the elemental contribution against devitrification and a consequent thermal stability. Cr is unfavorable towards ferromagnetic ordering leading to a linear drop in Curie temperature T{sub ca} with its rise in concentration. The presence of low Cr content upto Cr-4 at.% has been effective in drastically improving the Giant magneto-impedance (GMI) property. Cr content in the range of 4{<=}X{<=}10 has low magnetostriction and maximum field sensitivity in the as-quenched state. The GMI properties are further improved after annealing treatment. High content of Cr>10 is found to be deleterious towards GMI behavior and its consequent application as sensor material. - Highlights: Black-Right-Pointing-Pointer Cr incorporation in CoFeSiB alloy enhanced thermal stability against devitrification. Black-Right-Pointing-Pointer Optimal Cr content induced low magnetostriction in the rapidly quenched microwires. Black-Right-Pointing-Pointer High GMI ratio and field sensitivity was obtained with optimum Cr in the microwires. Black-Right-Pointing-Pointer Annealing treatment at 725 K for 15 min improved the GMI response of microwires.

Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

Science.gov (United States)

Anwar, M. S.; Prifiharni, S.; Mabruri, E.

2017-05-01

The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

A phase-field and electron microscopy study of phase separation in Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Hedstroem, Peter, E-mail: pheds@kth.se [Materials Science and Engineering, KTH (Royal Institute of Technology), SE-100 44 Stockholm (Sweden); Baghsheikhi, Saeed [Materials Science and Engineering, KTH (Royal Institute of Technology), SE-100 44 Stockholm (Sweden); Liu, Ping [Sandvik Materials Technology, R and D Centre, SE-81181 Sandviken (Sweden); Odqvist, Joakim [Materials Science and Engineering, KTH (Royal Institute of Technology), SE-100 44 Stockholm (Sweden); Sandvik Materials Technology, R and D Centre, SE-81181 Sandviken (Sweden)

2012-02-01

Highlights: Black-Right-Pointing-Pointer Experimental characterization and Phase-field modeling of phase separation in Fe-Cr. Black-Right-Pointing-Pointer Transition from particle-like to spinodal-like structure observed. Black-Right-Pointing-Pointer Structural evolution generates increased hardness. Black-Right-Pointing-Pointer Results in agreement with recent thermodynamic description. Black-Right-Pointing-Pointer Quantitative kinetic modeling must include thermal noise and improved kinetic data. - Abstract: Phase separation in the binary Fe-Cr system, the basis for the entire stainless steel family, is considered responsible for the low temperature embrittlement in ferritic, martensitic and duplex stainless steels. These steels are often used in load-bearing applications with considerable service time at elevated temperature. Thus, understanding the effect of microstructure on mechanical properties and predicting dynamics of phase separation are key issues. In the present work, experimental evaluation of structure and mechanical properties in binary Fe-Cr alloys as well as phase-field modeling, using a new thermodynamic description of Fe-Cr, is conducted. A significant hardening evolution with time is found for alloys aged between 400 and 550 Degree-Sign C, and it can be attributed to phase separation. The decomposed structure changed with increasing Cr content at 500 Degree-Sign C, with a more particle-like structure at 25 wt% Cr and a more spinodal-like structure at 30 wt% Cr. The observed transition of structure agrees with the thermodynamically predicted spinodal, although the transition is expected to be gradual. The phase-field simulations qualitatively agree with experiments. However, to enable accurate quantitative predictions, the diffusional mobilities must be evaluated further and thermal fluctuations as well as 3D diffusion fields must be properly accounted for.

KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr- 0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN

Directory of Open Access Journals (Sweden)

Sungkono Sungkono

2015-07-01

Full Text Available KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr-0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN. Logam paduan Zr-Nb-Fe-Cr dikembangkan sebagai material kelongsong elemen bakar dengan fraksi bakar tinggi untuk reaktor daya maju. Dalam penelitian ini telah dibuat paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr yang mendapat perlakuan panas pada temperatur 650 dan 750°C dengan waktu penahanan 1–2 jam. Tujuan penelitian adalah mendapatkan karakter paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas dan pengerolan dingin yaitu mikrostruktur, struktur kristal dan fasa-fasa yang ada dalam paduan. Hasil penelitian menunjukkan bahwa paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650ºC, 1-2 jam mempunyai struktur butir ekuiaksial dengan ukuran butir bertambah besar seiring dengan bertambahnya waktu penahanan. Sementara itu, pasca perlakuan panas (750ºC, 1-2 jam terjadi perubahan mikrostruktur paduan dari butir ekuiaksial dan kolumnar menjadi butir ekuiaksial lebih besar. Paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650°C, 1 jam dan (750°C, 1 jam tidak dapat dirol dingin dengan reduksi tebal 5 – 10%, sedangkan pasca perlakuan panas (650ºC, 2 jam dan (750°C, 1.5-2 jam mampu menerima deformasi dingin dengan reduksi ketebalan 5-10% tanpa mengalami keretakan. Senyawa Zr2Fe, ZrCr2 dan FeCr teridentifikai dari hasil uji kristalografi paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr.   MICROSTRUCTURE AND PHASE CHARACTERISTICSOF Zr-0.3%Nb-0.5%Fe-0.5%Cr ALLOY POST HEAT TREATMENT AND COLD ROLLING. Zr-Nb-Fe-Cr alloys was developed as fuel elements cladding with high burn up for advanced power reactors. In this research has been made of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy were heat treated with varying temperatures at650 and 750°C for 1 until 2 hours. The objectives of this research was to obtain the character of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment and cold rolling, microstructure nomenclature, crystal structure and phases that presents in the

A Eutectic Melting Study of Double Wall Cladding Tubes of FeCrAl and Zircaloy-4

Energy Technology Data Exchange (ETDEWEB)

Lim, Woojin; Son, Seongmin; Lee, You Ho; Lee, Jeong Ik; Ryu, Ho Jin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Jeong, Eun [Kyunghee University, Yongin (Korea, Republic of)

2015-10-15

The eutectic melting behavior of FeCrAl/Zircaloy-4 double wall cladding tubes was investigated by annealing at various temperatures ranging from 900 .deg. C to 1300 .deg. C. It was found that significant eutectic melting occurred after annealing at temperatures equal to or higher than 1150 .deg. C. It means that an additional diffusion barrier layer is necessary to limit the eutectic melting between FeCrAl and Zircaloy-4 alloy cladding tubes. Coating of FeCrAl layers on the Zr alloy cladding tube is being investigated for the development of accident tolerant fuel by exploiting of both the oxidation resistance of FeCrAl alloys and the neutronic advantages of Zr alloys. Coating of FeCrAl alloys on Zr alloy cladding tubes can be performed by various techniques including thermal spray, laser cladding, and co-extrusion. Son et al. also reported the fabrication of FeCrAl/Zr ally double wall cladding by the shrink fit method. For the double layered cladding tubes, the thermal expansion mismatch between the dissimilar materials, severe deformation or mechanical failure due to the evolution of thermal stresses can occur when there is a thermal cycling. In addition to the thermal stress problems, chemical compatibilities between the two different alloys should be investigated in order to check the stability and thermal margin of the double wall cladding at a high temperature. Generally, it is considered that Zr alloy cladding will maintain its mechanical integrity up to 1204 .deg. C (2200 .deg. F) to satisfy the acceptance criteria for emergency core cooling systems.

New carbazole-based Schiff base: Colorimetric chemosensor for Fe{sup 3+} and fluorescent turn-on chemosensor for Fe{sup 3+} and Cr{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Zhu, Weiju; Yang, Lianlian; Fang, Min; Wu, Zhenyu; Zhang, Qing; Yin, Fangfang; Huang, Qiang; Li, Cun, E-mail: cun_li@126.com

2015-02-15

Two novel carbazole-based Schiff-bases L1 and L2 have been synthesized and characterized by {sup 1}H NMR, {sup 13}C NMR, FT-IR spectroscopy and elemental analysis. L1 can selectively detect Fe{sup 3+} by UV–vis spectroscopy and Fe{sup 3+}/Cr{sup 3+} by fluorescent spectroscopy in CH{sub 3}CN among various metal ions. The addition of Fe{sup 3+} ions to a L1 solution results in a significant blue-shift from 410 nm to 378 nm accompanied with color change from yellowish green to colorless. Upon excitation at 380 nm, the addition of Fe{sup 3+} or Cr{sup 3+} causes a 13-fold or 11-fold fluorescence enhancement. The binding stoichiometry ratio of L1–Fe{sup 3+} and L1–Cr{sup 3+} is recognized as 2:1 by the method of Job's plot, and the possible binding mode of the system also proposes. The results indicate that L1 is an ideal chemosensor for Fe{sup 3+} and Cr{sup 3+} recognition. However, L2 without hydroxyl in ortho imino group cannot selectively recognize the tasted metal ions, indicating that the introduction of the appropriate coordination binding site to receptor can improve efficiently the selectivity of chemosensor. - Highlights: • We designed and synthesized two new carbazole-based Schiff bases L1 and L2. • L1 could selectively recognize Fe{sup 3+} but L2 could not, which suggested that increase recognition site helped to improve the selectivity of probe. • L1 not only could serve as a highly selective visual chemosensor for Fe{sup 3+} ion without the aid of any instruments, but also could be used as a fluorescent chemosensor for Fe{sup 3+} and Cr{sup 3+}.

Magnetic and hyperfine interactions in HoFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) compounds

Energy Technology Data Exchange (ETDEWEB)

Kotnana, Ganesh [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India); Reddy, V. Raghavendra [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Jammalamadaka, S. Narayana, E-mail: surya@iith.ac.in [Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India)

2017-05-01

We report on the magnetic and Mössbauer properties of polycrystalline HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. Magnetization data reveals the continuous tailoring of magnetic transition due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions in the entire temperature range by replacing the Fe{sup 3+} ions with Cr{sup 3+} ions. The observed decrease in Néel temperature (T{sub N}) and increase in spin re-orientation transition temperature (T{sub SR}) with the replacement of Fe{sup 3+} with Cr{sup 3+} is ascribed to the weakening of Fe(Cr)-O-Fe(Cr) antiferromagnetic exchange interaction. In addition, we also attribute such a change in T{sub N} to the enhancement of ferromagnetic interaction of adjacent Cr{sup 3+} moments through t-e hybridization as a result of the structural distortion. The decrease in isomer shift (IS) suggests enhancement of the interaction between nuclear charge with the 3s electrons as a result of decrease in radial part of 3d wave function with Cr addition. In this paper we also discuss about the variation of quadrupole splitting (QS) and hyperfine fields (H{sub hf}) with Cr addition in HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. - Highlights: • Magnetic and Mössbauer properties of HoFe{sub 1-x}Cr{sub x}O{sub 3} (0≤x≤1) compounds. • T{sub N} changes due to weakening of Ho{sup 3+}-Fe{sup 3+} and Fe{sup 3+}-Fe{sup 3+} interactions with Cr. • The decrease in isomer shift (IS) is due to decrease in radial part of 3d wavefunction. • Octahedral distortion leads to increase in quadrupole splitting.

Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

Directory of Open Access Journals (Sweden)

Pei-Chung Lin

2016-08-01

Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

Structural Properties of the Cr(III)-Fe(III) (Oxy)Hydroxide Compositional Series: Insights for a Nanomaterial 'Solid Solution'

International Nuclear Information System (INIS)

Tang, Y.; Zhang, L.; Michel, F.M.; Harrington, R.; Parise, J.B.; Reeder, R.J.

2010-01-01

Chromium(III) (oxy)hydroxide and mixed Cr(III)-Fe(III) (oxy)hydroxides are environmentally important compounds for controlling chromium speciation and bioaccessibility in soils and aquatic systems and are also industrially important as precursors for materials and catalyst synthesis. However, direct characterization of the atomic arrangements of these materials is complicated because of their amorphous X-ray properties. This study involves synthesis of the complete Cr(III)-Fe(III) (oxy)hydroxide compositional series, and the use of complementary thermal, microscopic, spectroscopic, and scattering techniques for the evaluation of their structural properties. Thermal analysis results show that the Cr end member has a higher hydration state than the Fe end member, likely associated with the difference in water exchange rates in the first hydration spheres of Cr(III) and Fe(III). Three stages of weight loss are observed and are likely related to the loss of surface/structural water and hydroxyl groups. As compared to the Cr end member, the intermediate composition sample shows lower dehydration temperatures and a higher exothermic transition temperature. XANES analysis shows Cr(III) and Fe(III) to be the dominant oxidation states. XANES spectra also show progressive changes in the local structure around Cr and Fe atoms over the series. Pair distribution function (PDF) analysis of synchrotron X-ray total scattering data shows that the Fe end member is nanocrystalline ferrihydrite with an intermediate-range order and average coherent domain size of ∼27 (angstrom). The Cr end member, with a coherent domain size of ∼10 (angstrom), has only short-range order. The PDFs show progressive structural changes across the compositional series. High-resolution transmission electron microscopy (HRTEM) results also show the loss of structural order with increasing Cr content. These observations provide strong structural evidence of chemical substitution and progressive structural

Microstructure and mechanical properties of FeCrAl alloys under heavy ion irradiations

Science.gov (United States)

Aydogan, E.; Weaver, J. S.; Maloy, S. A.; El-Atwani, O.; Wang, Y. Q.; Mara, N. A.

2018-05-01

FeCrAl ferritic alloys are excellent cladding candidates for accident tolerant fuel systems due to their high resistance to oxidation as a result of formation of a protective Al2O3 scale at high temperatures in steam. In this study, we report the irradiation response of the 10Cr and 13Cr FeCrAl cladding tubes under Fe2+ ion irradiation up to ∼16 dpa at 300 °C. Dislocation loop size, density and characteristics were determined using both two-beam bright field transmission electron microscopy and on-zone scanning transmission electron microscopy techniques. 10Cr (C06M2) tube has a lower dislocation density, larger grain size and a slightly weaker texture compared to the 13Cr (C36M3) tube before irradiation. After irradiation to 0.7 dpa and 16 dpa, the fraction of type sessile dislocations decreases with increasing Cr amount in the alloys. It has been found that there is neither void formation nor α‧ precipitation as a result of ion irradiations in either alloy. Therefore, dislocation loops were determined to be the only irradiation induced defects contributing to the hardening. Nanoindentation testing before the irradiation revealed that the average nanohardness of the C36M3 tube is higher than that of the C06M2 tube. The average nanohardness of irradiated tube samples saturated at 1.6-2.0 GPa hardening for both tubes between ∼3.4 dpa and ∼16 dpa. The hardening calculated based on transmission electron microscopy was found to be consistent with nanohardness measurements.

Reduction and Simultaneous Removal of ⁹⁹ Tc and Cr by Fe(OH) ₂ (s) Mineral Transformation

Energy Technology Data Exchange (ETDEWEB)

Saslow, Sarah A. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Um, Wooyong [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Pearce, Carolyn I. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Engelhard, Mark H. [Environmental; Bowden, Mark E. [Environmental; Lukens, Wayne [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States; Leavy, Ian I. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Riley, Brian J. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Kim, Dong-Sang [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Schweiger, Michael J. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Kruger, Albert A. [United

2017-07-17

Technetium (Tc) remains a priority remediation concern due to persistent challenges, including rapid re-oxidation of immobilized Tc, and competing contaminants, e.g. Cr(VI), that inhibit targeted Tc reduction and incorporation into stable mineral phases. Here Fe(OH)₂(s) is investigated as a comprehensive solution for overcoming these challenges, by serving as both the reductant, (Fe(II)), and immobilization agent to form Tc-incorporated magnetite (Fe₃O₄). Trace metal analysis suggests removal of Tc(VII) and Cr(VI) from solution occurs simultaneously; however, complete removal and reduction of Cr(VI) is achieved earlier than the removal/reduction of co-mingled Tc(VII). Bulk oxidation state analysis of the magnetite solid phase by XANES confirms that the majority of Tc is Tc(IV), which is corroborated by XPS. Furthermore, EXAFS results show successful Tc(IV) incorporation into magnetite octahedral sites without additional substitution of Cr or Tc into neighboring Fe octahedral sites. XPS analysis of Cr confirms reduction to Cr(III) and the formation of a Cr-incorporated spinel, Cr2O₃, and Cr(OH)3 phases. Spinel (modeled as Fe₃O₄), goethite, and feroxyhyte are detected in all reacted solid phase samples analyzed by XRD, where Tc(IV) incorporation has little effect on the spinel lattice structure. In the presence of Cr(III) a spinel phase along the magnetite-chromite (Fe₃O₄-FeCr₂O₄) solid-solution line is formed.

Study of phase transformations in Fe-Mn-Cr Alloys

International Nuclear Information System (INIS)

Schule, W.; Panzarasa, A.; Lang, E.

1988-01-01

Nickel free alloys for fusion reactor applications are examined. Phase changes in fifteen, mainly austenitic iron-manganese-chromium-alloys of different compositions were investigated in the temperature range between -196 0 C and 1000 0 C after different thermo-mechanical treatments. A range of different physical measuring techniques was employed to investigate the structural changes occurring during heating and cooling and after cold-work: electrical resistivity techniques, differential thermal analysis, magnetic response, Vickers hardness and XRD measurement. The phase boundary between the α Fe-phase and the γ-phase of the iron manganese alloy is approximately maintained if chromium is added to the two component materials. Consequently all the alloy materials for contents of manganese smaller than about 30% Mn are not stable below 500 0 C. This concerns also the AMCR alloys. However the α Fe-phase is not formed during slow cooling from 1000 0 C to ambient temperature and is only obtained if nucleation sites are provided and after very long anneals. A cubic α Mn-type-phase is found for alloys with 18% Cr and 15% Mn, with 13% Cr and 25% Mn, with 10% Cr and 30% Mn, and with 10% Cr and 40% Mn. For these reasons the γ-phase field of the iron-chromium-manganese alloys is very small below 600 0 C and much narrower than reported in the literature. 95 figs. 22 refs

Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

Science.gov (United States)

Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

2013-10-01

We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

Enhanced Cr(VI) removal from groundwater by Fe0-H2O system with bio-amended iron corrosion

DEFF Research Database (Denmark)

Yin, Weizhao; Li, Yongtao; Wu, Jinhua

2017-01-01

Abstract A one-pot bio-iron system was established to investigate synergetic abiotic and biotic effects between iron and microorganisms on Cr(VI) removal. More diverse iron corrosion and reactive solids, such as green rusts, lepidocrocite and magnetite were found in the bio-iron system than...... transfer on the solid phase. The results also showed that the reduction of Cr(VI) by microorganisms was insignificant, indicating the adsorption/co-precipitation of Cr by iron oxides on iron surface was responsible for the overall Cr(VI) removal. Our study demonstrated that the bio-amended iron corrosion...... in the Fe0-H2O system, leading to 4.3 times higher Cr(VI) removal efficiency in the bio-iron system than in the Fe0-H2O system. The cycling experiment also showed that the Cr(VI) removal capacity of Fe0 in the bio-iron system was 12.4 times higher than that in the Fe0-H2O system. A 62 days of life...

On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

Directory of Open Access Journals (Sweden)

Anna M. Manzoni

2016-03-01

Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

Science.gov (United States)

Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

2018-05-01

High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

Magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound

Science.gov (United States)

Kotnana, Ganesh; Babu, P. D.; Jammalamadaka, S. Narayana

2018-05-01

We report on the magnetic and magnetocaloric properties of HoCr0.75Fe0.25O3 compound around the Néel temperature (TN), which is due to Cr3+ ordering. Susceptibility (χ) vs. temperature (T) graph of HoCr0.75Fe0.25O3 compound infer two transitions due to the ordering of Cr3+ moments (TN ˜ 155 K) and Ho3+ moments (TNHo ˜ 8 K). Magnetic entropy (-ΔSM) value of 1.14 J kg-1 K-1 around 157.5 K with a magnetic field (H) of 90 kOe is attributed to antiferromagnetic (AFM) ordering of Cr3+ moments. A maximum value of adiabatic temperature (ΔTad) ˜ 0.41 K around TN is obtained and is found to increases with applied magnetic field. Negative slope for H/M vs. M2 graph is evident for HoCr0.75Fe0.25O3 compound below TN, which indicates the first order phase transition. Quantified values of -ΔSM and ΔTad open the way to explore rare earth orthochromites for the MCE properties and refrigeration applications.

Oxide scale formation of modified FeCrAl coatings exposed to liquid lead

Energy Technology Data Exchange (ETDEWEB)

Fetzer, Renate, E-mail: renate.fetzer@kit.edu [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Weisenburger, Alfons; Jianu, Adrian; Mueller, Georg [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Modified FeCrAl coatings show oxide scale formation when exposed to liquid lead. Black-Right-Pointing-Pointer Formation of thin Al-rich oxide scales is promoted by the presence of Y. Black-Right-Pointing-Pointer FeCrAlY with at least 8 wt.% Al forms thin Al-rich oxide scales. Black-Right-Pointing-Pointer For low Al content, thick multilayer Fe-based oxide scales are found. - Abstract: Modified FeCrAl coatings were studied with respect to their capability to form a thin protective oxide scale in liquid lead environment. They were manufactured by low pressure plasma spraying and GESA surface melting, thereby tuning the Al content. The specimens were exposed for 900 h to liquid lead containing 10{sup -6} and 10{sup -8} wt.% oxygen, respectively, at various temperatures from 400 to 550 Degree-Sign C. Threshold values for an Al content that guarantees the formation of thin protective Al-rich oxide scales are determined, dependent on the respective chromium content, on the presence of yttrium in the modified coating, and on the exposure conditions.

A preparation method and effects of Al-Cr coating on NdFeB sintered magnets

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jingwu [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Lin, Min, E-mail: linm@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, 519 Road Zhuangshi, District Zhenghai, Ningbo 315201, People' s Republic of China (China); Xia, Qingping [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

2012-11-15

A 50 {mu}m Al-Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 Degree-Sign C. The morphology and composition of the Al-Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al-Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al-Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al-Cr coating moves positively from -0.67 to -0.48 V, which is in accordance with Nyquist and Bode plots. The Al-Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: Black-Right-Pointing-Pointer The Al-Cr coating can be prepared by dipping in solution, shaking dry and heating. Black-Right-Pointing-Pointer The coating morphology shows to be an intense overlapping structure. Black-Right-Pointing-Pointer The barrier effect combines with passivation and cathodic protection. Black-Right-Pointing-Pointer The anticorrosion abilities improve while magnetic properties change little. Black-Right-Pointing-Pointer Compared with other surface treatments, this method is convenient and low cost.

Modification of Surface Roughness and Area of FeCrAl Substrate for Catalytic Converter using Ultrasonic Treatment

Directory of Open Access Journals (Sweden)

Yanuandri Putrasari

2012-03-01

Full Text Available Surface roughness and area play important role especially in deposition and reaction of the catalyst in the catalytic converter substrate. The aim of this paper is to show the modification of surface roughness and area of FeCrAl substrate for catalytic converter using ultrasonic method. The method was conducted by agitating the FeCrAl in 10 minutes 35 kHz ultrasonic cleaning bath. The  surface roughness, morphology, and chemical components of FeCrAl catalytic converter substrate after ultrasonic treatment were analyzed using atomic force microscope (AFM and examined with scanning electron microscope (SEM in combination with energy dispersive X-ray spectroscopy (EDS. The ultrasonic treatment assisted with Al2O3 powders successfully increased the roughness and surface area of FeCrAl better than SiC powders. 

Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

International Nuclear Information System (INIS)

Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

2005-01-01

In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

Crystal structure and magnetic properties of the Cr-doped spiral antiferromagnet BiMnFe{sub 2}O{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Batuk, Dmitry, E-mail: Dmitry.batuk@ua.ac.be [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Tsirlin, Alexander A. [National Institute of Chemical Physics and Biophysics, 12618, Tallinn (Estonia); Abakumov, Artem M. [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium); Hardy, An; Van Bael, Marlies K. [Inorganic and Physical Chemistry Group, Hasselt University, Institute for Materials Research, Agoralaan Building D, B-3590, Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Agoralaan Building D, B-3590, Diepenbeek (Belgium); Greenblatt, Martha [Department of Chemistry and Chemical Biology, Rutgers, State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey, 08854-8087 (United States); Hadermann, Joke [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp (Belgium)

2013-09-01

Graphical abstract: - Highlights: • The substitution of Cr for Mn in BiMnFe{sub 2}O{sub 6} is possible by the solution–gel method. • The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained for the x values up to 0.3. • Increasing Cr content lowers the temperature of the antiferromagnetic ordering. - Abstract: We report the Cr{sup 3+} for Mn{sup 3+} substitution in the BiMnFe{sub 2}O{sub 6} structure. The BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} solid solution is obtained by the solution–gel synthesis technique for the x values up to 0.3. The crystal structure investigation using a combination of X-ray powder diffraction and transmission electron microscopy demonstrates that the compounds retain the parent BiMnFe{sub 2}O{sub 6} structure (for x = 0.3, a = 5.02010(6)Å, b = 7.06594(7)Å, c = 12.6174(1)Å, S.G. Pbcm, R{sub I} = 0.036, R{sub P} = 0.011) with only a slight decrease in the cell parameters associated with the Cr{sup 3+} for Mn{sup 3+} substitution. Magnetic susceptibility measurements suggest strong similarities in the magnetic behavior of BiCr{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 6} (x = 0.2; 0.3) and parent BiMnFe{sub 2}O{sub 6}. Only T{sub N} slightly decreases upon Cr doping that indicates a very subtle influence of Cr{sup 3+} cations on the magnetic properties at the available substitution rates.

Multiwall carbon nanotubes decorated with FeCr{sub 2}O{sub 4}, a new selective electrochemical sensor for amoxicillin determination

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali Asghar, E-mail: Ensafi@cc.iut.ac.ir; Allafchian, Ali Reza; Rezaei, Behzad [Isfahan University of Technology, Department of Chemistry (Iran, Islamic Republic of)

2012-11-15

FeCr{sub 2}O{sub 4} nanoparticles were synthesized and then multiwall carbon nanotubes (MWCNTs) were decorated with FeCr{sub 2}O{sub 4} nanoparticles. The new nanoparticles were characterized with different techniques such as vibrating sample magnetometer, Fourier transform infrared spectroscopy, scanning surface microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. The results of the study confirm that the particles are pure FeCr{sub 2}O{sub 4}-MWCNTs with a cubic structure. No diffraction peaks of other impurities such as FeO or Cr{sub 2}O{sub 3} were observed. The diffractive peaks of FeCr{sub 2}O{sub 4}-MWCNTs are broadened, implying that the crystalline size of FeCr{sub 2}O{sub 4}-MWCNTs particles is quite small. The mean particle size of FeCr{sub 2}O{sub 4}-MWCNTs calculated by Scherrer equation is about 25 nm, whereas the existence of particles with less than 30 nm size at FeCr{sub 2}O{sub 4}-MWCNTs is clearly reflected in 2D and 3D AFM images. The TEM image confirms that the spaghetti-like FeCr{sub 2}O{sub 4}-MWCNTs formed a porous structure. The synthesized FeCr{sub 2}O{sub 4}-MWCNTs nanoparticles could be used as a new electrocatalysis for voltammetric determination of amoxicillin (AMC). Under the optimized conditions at pH 7.5 and in differential pulse voltammetry, the oxidation peak current of AMC at the surface of the mediator has two linear dynamic ranges including 0.1-10.0 and 10.0-70.0 {mu}mol L{sup -1}. The detection limit of 0.05 {mu}mol L{sup -1} was achieved. The influence of potential interfering compounds on the selectivity was studied. Finally, the modified electrode showed good sensitivity, selectivity, and stability for the determination of AMC in real samples.

Effect of Organic Matter on Cr(VI Removal from Groundwaters by Fe(II Reductive Precipitation for Groundwater Treatment

Directory of Open Access Journals (Sweden)

Anna Gröhlich

2017-06-01

Full Text Available Due to its toxicity, Cr(VI is undesirable in groundwater. Its chemical reduction to Cr(III species, followed by precipitation is the most widely practiced treatment technique for the removal of Cr(VI from polluted waters. The resulting Cr(III species present low solubility, is much less toxic, and can be subsequently removed either by precipitation, or by adsorption onto iron oxy-hydroxides and co-precipitation. The effects of several parameters, such as the pH value of water to be treated, the applied Fe(II dose, and the presence of appropriate mineral surfaces, are well investigated and understood. However, the impact of the presence of humic acids (HAs in this process has only been considered by rather few studies. The main aim of this study was to determine the effect of humic substances on Fe(II reductive precipitation of Cr(VI within a pH range relevant for drinking water treatment. Jar test experiments were performed, using artificial groundwater of defined composition and initial Cr(VI concentration 100 μg/L, ferrous sulphate dosages 0.25–2 mg Fe(II/L, and pH values 6.5–8. It was found that Cr(VI and total chromium (Cr(total can be reliably removed in the absence of HAs in the tested pH range with the addition of Fe(II dosage of 1 mg Fe(II/L. Further on, the results indicated that the reduction of Cr(VI is only slightly affected by the presence of HAs. However, increased residual total Cr concentrations were found at lower Fe(II dosages and/or higher pH values. Additionally, the removal of the Cr(III species formed during Cr(VI reduction was strongly inhibited by the presence of HAs under the examined experimental conditions, since residual concentrations higher than 60 μg/L were determined. The results of this study will have implications to the ongoing discussion of a new, stricter, European Union regulation limit, regarding the presence of total chromium in drinking water.

Plasma spraying of Fe-Cr-Al alloy powder

Czech Academy of Sciences Publication Activity Database

Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

2008-01-01

Roč. 46, č. 1 (2008), s. 17-25 ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

Cl K-edge XANES spectra of atmospheric rust on Fe, Fe-Cr and Fe-Ni alloys exposed to saline environment

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2004-01-01

Cl K-edge XANES measurements of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys in chloride pollution have been performed using synchrotron radiation in order to clarify roles of anticorrosive alloying elements and of Cl in the corrosion resistance of weathering steel. The spectra of binary alloys show a shoulder structure near the absorption edge. The intensity of the shoulder peak depends on the kind and amount of the alloying element, whereas the energy position is invariant. This indicates that Cl is not combined directly with alloying elements in the rust. (author)

Fabrication and characterization of He-charged ODS-FeCrNi films deposited by a radio-frequency plasma magnetron sputtering technique

Science.gov (United States)

Song, Liang; Wang, Xianping; Wang, Le; Zhang, Ying; Liu, Wang; Jiang, Weibing; Zhang, Tao; Fang, Qianfeng; Liu, Changsong

2017-04-01

He-charged oxide dispersion strengthened (ODS) FeCrNi films were prepared by a radio-frequency (RF) plasma magnetron sputtering method in a He and Ar mixed atmosphere at 150 °C. As a comparison, He-charged FeCrNi films were also fabricated at the same conditions through direct current (DC) plasma magnetron sputtering. The doping of He atoms and Y2O3 in the FeCrNi films was realized by the high backscattered rate of He ions and Y2O3/FeCrNi composite target sputtering method, respectively. Inductive coupled plasma (ICP) and x-ray photoelectron spectroscopy (XPS) analysis confirmed the existence of Y2O3 in FeCrNi films, and Y2O3 content hardly changed with sputtering He/Ar ratio. Cross-sectional scanning electron microscopy (SEM) shows that the FeCrNi films were composed of dense columnar nanocrystallines and the thickness of the films was obviously dependent on He/Ar ratio. Nanoindentation measurements revealed that the FeCrNi films fabricated through DC/RF plasma magnetron sputtering methods exhibited similar hardness values at each He/Ar ratio, while the dispersion of Y2O3 apparently increased the hardness of the films. Elastic recoil detection (ERD) showed that DC/RF magnetron sputtered FeCrNi films contained similar He amounts (˜17 at.%). Compared with the minimal change of He level with depth in DC-sputtered films, the He amount decreases gradually in depth in the RF-sputtered films. The Y2O3-doped FeCrNi films were shown to exhibit much smaller amounts of He owing to the lower backscattering possibility of Y2O3 and the inhibition effect of nano-sized Y2O3 particles on the He element.

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe3O4/halloysite nanohybrid.

Science.gov (United States)

Tian, Xike; Wang, Weiwei; Tian, Na; Zhou, Chaoxin; Yang, Chao; Komarneni, Sridhar

2016-05-15

In this work, a novel "Dumbbell-like" magnetic Fe3O4/Halloysite nanohybrid (Fe3O4/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe3O4 nanospheres selectively aggregating at the tips of modified halloysite nanotubes was successfully synthesized. XRD, TEM, IR spectroscopy, XPS and VSM were used to characterize this newly halloysite nanohybrid and its formation mechanism was discussed. Cr(VI) ions adsorption experiments showed that the Fe3O4/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe3O4 and electron-donor effect of oxygen-containing organic groups, Cr(VI) ions were easily reduced into low toxicity Cr(III) and then adsorbed onto the surface of halloysite nanohybrid. In addition, appreciable magnetization was observed due to the aggregation of magnetite nanoparticles, which make adsorbent facility separated from aqueous solutions after Cr pollution adsorption. Copyright © 2016 Elsevier B.V. All rights reserved.

The reactivity of Fe(II) associated with goethite formed during short redox cycles toward Cr(VI) reduction under oxic conditions

Energy Technology Data Exchange (ETDEWEB)

Tomaszewski, Elizabeth J.; Lee, Seungyeol; Rudolph, Jared; Xu, Huifang; Ginder-Vogel, Matthew (UW)

2017-08-01

Chromium (Cr) is a toxic metal that causes a myriad of health problems and enters the environment as a result of anthropogenic activities and/or natural processes. The toxicity and solubility of chromium is linked to its oxidation state; Cr(III) is poorly soluble and relatively nontoxic, while Cr(VI) is soluble and a known carcinogen. Solid Fe(II) in iron-bearing minerals, such as pyrite, magnetite, and green rusts, reduce the oxidation state of chromium, reducing its toxicity and mobility. However, these minerals are not the only potential sources of solid-associated Fe(II) available for Cr(VI) reduction. For example, ferric (Fe(III)) (hydr)oxides, such as goethite or hematite, can have Fe(II) in the solid without phase transformation; however, the reactivity of Fe(II) within Fe(III) (hydr)oxides with contaminants, has not been previously investigated. Here, we cyclically react goethite with dissolved Fe(II) followed by dissolved O2, leading to the formation of reactive Fe(II) associated with goethite. In separate reactors, the reactivity of this Fe(II) is probed under oxic conditions, by exposure to chromate (CrO42 -) after either one, two, three or four redox cycles. Cr is not present during redox cycling; rather, it is introduced to a subset of the solid after each oxidation half-cycle. Analysis of X-ray absorption near edge structure (XANES) spectra reveals that the extent of Cr(VI) reduction to Cr(III) depends not only on solid Fe(II) content but also surface area and mean size of ordered crystalline domains, determined by BET surface area analysis and X-ray diffraction (XRD), respectively. Shell-by-shell fitting of the extended X-ray absorption fine structure (EXAFS) spectra demonstrates chromium forms both single and double corner sharing complexes on the surface of goethite, in addition to sorbed Cr(III) species. Finally, transmission electron microscope (TEM) imaging and X-ray energy-dispersive spectroscopy (EDS) illustrate that Cr preferentially

Influence of manganese, carbon and nitrogen on high-temperature strength of Fe-Cr-Mn austenitic alloys

International Nuclear Information System (INIS)

Hosoi, Y.; Okazaki, Y.; Wade, N.; Miyahara, K.

1990-01-01

High Mn-Cr-Fe base alloys are candidates for the first wall material of fusion reactors because of rapid decay of radioactivity of the alloys after neutron irradiation compared with that of Ni-Cr-Fe base alloys. Their high temperature properties, however, are not clearly understood at present. In this paper, a study has been made of the effects of Mn, C and N content on the high-temperature tensile strength and creep properties of a 12% CR-Fe base alloy. Mn tends to decrease tensile strength and proof stress at intermediate temperatures. At higher temperatures in the austenite range, however, tensile properties scarcely depend on Mn content. C and N additions improve the tensile properties markedly. The combined addition of 0.2%C and 0.2%N to a 12%Cr-15%Mn-Fe base alloy makes the strength at 873K as high as that of a modified type 316 stainless steel. Combined alloying with C and N also improves the creep strength. Cold working is very useful in increasing the creep strength because of the finely dispersed precipitates in the matrix during creep. From these results, Fe-12%Cr-15%Mn-15%Mn-0.2%c-0.2%N is recommended as one of the most suitable alloys in this system for high temperature usage. (author)

Oxidation Behavior of FeCrAl -coated Zirconium Cladding prepared by Laser Coating

Energy Technology Data Exchange (ETDEWEB)

Kim, Il-Hyun; Kim, Hyun-Gil; Choi, Byung-Kwan; Park, Jeong-Yong; Koo, Yang-Hyun; Kim, Jin-Seon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

From the recent research trends, the ATF cladding concepts for enhanced accident tolerance are divided as follows: Mo-Zr cladding to increase the high temperature strength, cladding coating to increase the high temperature oxidation resistance, FeCrAl alloy and SiC/SiCf material to increase the oxidation resistance and strength at high temperature. To commercialize the ATF cladding concepts, various factors are considered, such as safety under normal and accident conditions, economy for the fuel cycle, and developing development challenges, and schedule. From the proposed concepts, it is known that the cladding coating, FeCrAl alloy, and Zr-Mo claddings are considered as a near/mid-term application, whereas the SiC material is considered as a long-term application. Among them, the benefit of cladding coating on Zr-based alloys is the fuel cycle economy regarding the manufacturing, neutron cross section, and high tritium permeation characteristics. However, the challenge of cladding coating on Zr-based alloys is the lower oxidation resistance and mechanical strength at high-temperature than other concepts. Another important point is the adhesion property between the Zr-based alloy and coating materials. A laser coating method supplied with FeCrAl powders was developed to decrease the high-temperature oxidation rate in a steam environment through a systematic study for various coating parameters, and a FeCrAl-coated Zircaloy-4 cladding tube of 100 mm in length to the axial direction can be successfully manufactured.

Giant magnetoresistance in CrFeMn alloys

International Nuclear Information System (INIS)

Xu, W.M.; Zheng, P.; Chen, Z.J.

1997-01-01

The electrical resistance and longitudinal magnetoresistance of Cr 75 (Fe x Mn 1-x ) 25 alloys, x=0.64, 0.72, are studied in the temperature range 1.5-270 K in applied field up to 7.5 T. The magnetoresistance is negative and strongly correlated with the spin reorientation. In the temperature range where the antiferromagnetic and ferromagnetic domains coexist, the samples display giant magnetoresistance which follows a H n -law at high field. (orig.)

Evolution of the electronic structure and physical properties of Fe2MeAl (Me = Ti, V, Cr) Heusler alloys

International Nuclear Information System (INIS)

Shreder, E; Streltsov, S V; Svyazhin, A; Makhnev, A; Marchenkov, V V; Lukoyanov, A; Weber, H W

2008-01-01

We present the results of experiments on the optical, electrical and magnetic properties and electronic structure and optical spectrum calculations of the Heusler alloys Fe 2 TiAl, Fe 2 VAl and Fe 2 CrAl. We find that the drastic transformation of the band spectrum, especially near the Fermi level, when replacing the Me element (Me = Ti, V, Cr), is accompanied by a significant change in the electrical and optical properties. The electrical and optical properties of Fe 2 TiAl are typical for metals. The abnormal behavior of the electrical resistivity and the optical properties in the infrared range for Fe 2 VAl and Fe 2 CrAl are determined by electronic states at the Fermi level. Both the optical spectroscopic measurements and the theoretical calculations demonstrate the presence of low-energy gaps in the band spectrum of the Heusler alloys. In addition, we demonstrate that the formation of Fe clusters may be responsible for the large enhancement of the total magnetic moment in Fe 2 CrAl

Sintering behavior, microstructure and properties of TiC-FeCr hard alloy

Institute of Scientific and Technical Information of China (English)

Farid Akhtar; Shiju Guo; Jawid Askari; Jianjun Tian

2007-01-01

TiC based cermets were produced with FeCr,as a binder,by conventional P/M (powder metallurgy) to near ＞97% of the theoretical density.Sintering temperature significantly affects the mechanical properties of the composite.The sintering temperature of＞1360 ℃ caused severe chemical reaction between TiC particles and the binder phase.In the TiC-FeCr cermets,the mechanical properties did not vary linearly with the carbide content.Optimum mechanical properties were found in the composite containing 57wt%TiC reinforcement,when sintered at 1360 ℃ for 1 h.Use of carbon as an additive enhanced the mechanical properties of the composites.Cermets containing carbon as an additive with 49wt% TiC exhibited attractive mechanical properties.The microstructure of the developed composite contained less or no debonding,representing good wettability of the binder with TiC particles.Homogeneous distribution of the TiC particles ensured the presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite.Preliminary experiments for evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.

The corrosion and mechanical behaviour of Al, FeCrAlY, and CoCrAlY coatings in aggressive environments

NARCIS (Netherlands)

Haanappel, V.A.C.; Haanappel, V.A.C.; Geerdink, Bert; Fransen, T.; Gellings, P.J.

1991-01-01

The mechanical and chemical behaviours of aluminide coatings applied by pack cementation, FeCrAlY coatings applied by plasma spraying and CoCrAlY coatings applied by electrodeposition were studied. The coatings were pretreated for 0.5 h in argon at 1373 K to improve the adhesion and structural

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

Energy Technology Data Exchange (ETDEWEB)

Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

2017-02-28

Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

Effects of environment on the release of Ni, Cr, Fe, and Co from new and recast Ni-Cr alloy.

Science.gov (United States)

Oyar, Perihan; Can, Gülşen; Atakol, Orhan

2014-07-01

The addition of previously cast alloy to new alloy for economic reasons may increase the release of elements. The purpose of this study was to analyze the effects of the immersion period, immersion media, and addition of previously cast alloy to new alloy on the release of elements. Disk-shaped specimens were prepared from a Ni-Cr alloy (Ni: 61 wt%, Cr: 26 wt%, Mo: 11 wt%, Si: 1.5 wt%, Fe, Ce, Al, and Co alloy (group N) and 50% new/50% recast alloy (group R). After the immersion of the specimens in both NaCl (pH 4) and artificial saliva (pH 6.7) for 3, 7, 14, 30, and 60 days, the release of ions was determined by using atomic absorption spectrometry. Data were analyzed with a 3-way ANOVA (α=.001). The release of Ni was significantly affected by the immersion period, of Ni and Cr by the alloy and media (Palloy (Palloy in artificial saliva was 109.71 for Ni, 6.49 for Cr, 223.22 for Fe, and 29.90 μg/L for Co. The release of Co in NaCl was below the detection limit in both groups. The release of Ni in NaCl and artificial saliva increased with the length of the immersion period in both groups. The release of Cr and Fe was higher in artificial saliva than in NaCl in group R, regardless of the immersion period. The release of Co in NaCl was below the detection limit in both groups. Copyright © 2014 The Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Tensile ductility of an AlCoCrFeNi multi-phase high-entropy alloy through hot isostatic pressing (HIP) and homogenization

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhi, E-mail: Zhi.Tang@alcoa.com [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061 (United States); Senkov, Oleg N. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH 45433 (United States); Parish, Chad M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhang, Chuan; Zhang, Fan [CompuTherm LLC, 437 S. Yellowstone Dr., Suite 217, Madison, WI 53719 (United States); Santodonato, Louis J. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wang, Gongyao [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Zhao, Guangfeng; Yang, Fuqian [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Liaw, Peter K., E-mail: pliaw@utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

2015-10-28

The microstructure and phase composition of an AlCoCrFeNi high-entropy alloy (HEA) were studied in as-cast (AlCoCrFeNi-AC, AC represents as-cast) and homogenized (AlCoCrFeNi-HP, HP signifies hot isostatic pressed and homogenized) conditions. The AlCoCrFeNi-AC ally has a dendritric structure in the consisting primarily of a nano-lamellar mixture of A2 (disordered body-centered-cubic (BCC)) and B2 (ordered BCC) phases, formed by an eutectic reaction. The homogenization heat treatment, consisting of hot isostatic pressed for 1 h at 1100 °C, 207 MPa and annealing at 1150 °C for 50 h, resulted in an increase in the volume fraction of the A1 phase and formation of a Sigma (σ) phase. Tensile properties in as-cast and homogenized conditions are reported at 700 °C. The ultimate tensile strength was virtually unaffected by heat treatment, and was 396±4 MPa at 700 °C. However, homogenization produced a noticeable increase in ductility. The AlCoCrFeNi-AC alloy showed a tensile elongation of only 1.0%, while after the heat-treatment, the elongation of AlCoCrFeNi-HP was 11.7%. Thermodynamic modeling of non-equilibrium and equilibrium phase diagrams for the AlCoCrFeNi HEA gave good agreement with the experimental observations of the phase contents in the AlCoCrFeNi-AC and AlCoCrFeNi-HP. The reasons for the improvement of ductility after the heat treatment and the crack initiation subjected to tensile loading were discussed.

Effects of a FeCrAl layer fabricated by sputtering process on pool boiling critical heat flux

International Nuclear Information System (INIS)

Seo, Gwang Hyeok; Son, Hong Hyun; Jeun, Gyoodong; Kim, Sung Joong

2016-01-01

The thermal safety margin of a FeCrAl-layered heater was investigated measuring pool boiling critical heat flux (CHF). Boiling experiments were conducted in a pool of deionized water at atmospheric pressure. For a comparison work, bare and FeCrAl-layered heater samples were prepared. The sputtering technique was employed to fabricate the FeCrAl layer. It was confirmed that the key sputtering parameters on the surface structure were substrate temperature and deposition time. As compared to the bare sample, surface wettability and roughness increased. Higher values of the surface roughness were observed at temperatures of 150degC and 600degC. The FeCrAl-layered heaters showed improved CHF up to ∼40%. The highest enhancement of 42% was observed for the heater sample fabricated at a substrate temperature of 150degC. With employing recent CHF models that incorporate the surface effects, it was evaluated that increased roughness at the micrometer scale mainly contributed to the CHF enhancement. Furthermore, visual observations showed at least 2 msec reduction in the rewetting times for the FeCrAl-layered heaters, and the improved CHF may be attributed to the suppressed hot dry spots due to the rewetting phenomena. (author)

Effect of d electrons on defect properties in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys

Science.gov (United States)

Zhao, Shijun; Egami, Takeshi; Stocks, G. Malcolm; Zhang, Yanwen

2018-01-01

The role of d electrons in determining distributions of formation and migration energies for point defects in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys (CSAs) are studied regarding electron density deformation flexibility based on first-principles calculations. The disordered state is taken into account by constructing special quasirandom structures. The migration barriers are determined by directly optimizing the saddle point. It is found that the formation energies of interstitials in CSAs are lower than those in pure Ni, whereas the formation energies of vacancies are higher. In both NiCoCr and NiCoFeCr, Co-related dumbbell interstitials exhibit lower formation energies. Notably, the distributions of migration energies for Cr interstitials and vacancies exhibit a remarkable overlap region. A detailed analysis of electronic properties reveals that the electronic charge deformation flexibility regarding eg to t2g transition has a dominant effect on defect energetics for different elements in CSAs. Thus the electron deformation ability is suggested as a key factor in understanding the peculiar defect behavior in CSAs.

On the evaluation of residual stress and mechanical properties of FeCrBSi coatings by nanoindentation

International Nuclear Information System (INIS)

Zhu Lina; Xu Binshi; Wang Haidou; Wang Chengbiao

2012-01-01

Highlights: ► Ni/Al coating can reduce the mismatch degree between the coating and substrate. ► No obvious pile-up is observed for the nanoindents of the FeCrBSi coating. ► The higher the tensile residual stress, the lower the hardness and elastic modulus. - Abstract: In this paper, the residual stress in the plasma-sprayed FeCrBSi coating was determined by nanoindentation and X-ray diffraction (XRD). The XRD results showed that tensile residual stress was generated in the FeCrBSi coating, and the through-thickness values range between 40 MPa and 112 MPa. The residual stress measured by nanoindentation is 753 MPa. The difference between the XRD and nanoindentation results was discussed. It is found that the factors limiting the nanoindentation measurement of residual stress include the ‘sink-in’ deformation around the indenter, the roughness of the FeCrBSi coating, and the use of reference sample without residual stress. The above three factors lead to the over-prediction of residual stress by nanoindentation.

Magnetic properties of pure and Fe doped HoCrO{sub 3} thin films fabricated via a solution route

Energy Technology Data Exchange (ETDEWEB)

Yin, Shiqi; Sauyet, Theodore [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Guild, Curt [Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Suib, S.L. [Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Jain, Menka, E-mail: menka.jain@uconn.edu [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

2017-04-15

Multiferroic properties of orthorhombically distorted perovskite rare-earth chromites, such as HoCrO{sub 3}, are being investigated extensively in recent years. In the present work, we report on the effect of Fe substitution on the magnetic properties of HoCrO{sub 3} thin films. Thin films of HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} were fabricated via a solution route on platinized silicon substrates. Structural properties of the films were evaluated by X-ray diffraction and Raman spectroscopy techniques. The surface morphology and cross-sections of the films were examined using scanning electron microscopy. Optical band gaps of pure and Fe doped HoCrO{sub 3} films are found to be 3.45 eV and 3.39 eV, respectively. The magnetization measurements show that the Néel temperatures (where Cr{sup 3+} orders) for the HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} films are 134 and 148 K, respectively. In a magnetic field of 2 T, the maximum entropy change and relative cooling power, two parameters to evaluate the magnetocaloric properties of a material, were 0.813 J/kg K at 11 K and 21.1 J/kg for HoCrO{sub 3} film, in comparison with 0.748 J/kg K at 15 K and 26.8 J/kg for HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} film. To our knowledge, this is the first work exploring the band gap and magnetocaloric properties of rare-earth chromite thin films. These findings should inspire the development of rare-earth chromite thin films for temperature control of nanoscale electronic devices and sensors in the low temperature region (< 30 K). - Highlights: • Phase-pure HoCrO{sub 3} and HoCr{sub 0.7}Fe{sub 0.3}O{sub 3}films were fabricated on platinized Sivia a solution route. • This is the first work on the exploration of band gap and magnetocaloric properties of rare-earth chromitefilms. • From 0-2 T, maximum entropy change for the HoCrO{sub 3} film was 0.813 J/kg K at 11 K.From 0-2 T, maximum entropy change for HoCr{sub 0.7}Fe{sub 0.3}O{sub 3} film was 0.748 J/kg K at 15

Unraveling the magnetic properties of BiFe0.5Cr0.5O3 thin films

Directory of Open Access Journals (Sweden)

G. Vinai

2015-11-01

Full Text Available We investigate the structural, chemical, and magnetic properties on BiFe0.5Cr0.5O3 (BFCO thin films grown on (001 (110 and (111 oriented SrTiO3 (STO substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

Synthesis and Characterization of High-Entropy Alloy AlFeCoNiCuCr by Laser Cladding

Directory of Open Access Journals (Sweden)

Xiaoyang Ye

2011-01-01

Full Text Available High-entropy alloys have been recently found to have novel microstructures and unique properties. In this study, a novel AlFeCoNiCuCr high-entropy alloy was prepared by laser cladding. The microstructure, chemical composition, and constituent phases of the synthesized alloy were characterized by SEM, EDS, XRD, and TEM, respectively. High-temperature hardness was also evaluated. Experimental results demonstrate that the AlFeCoNiCuCr clad layer is composed of only BCC and FCC phases. The clad layers exhibit higher hardness at higher Al atomic content. The AlFeCoNiCuCr clad layer exhibits increased hardness at temperature between 400–700°C.

Interplay between magnetism and energetics in Fe-Cr alloys from a predictive noncollinear magnetic tight-binding model

DEFF Research Database (Denmark)

Soulairol, R.; Barreteau, Cyrille; Fu, Chu-Chun

2016-01-01

Magnetism is a key driving force controlling several thermodynamic and kinetic properties of Fe-Cr systems. We present a tight-binding model for Fe-Cr, where magnetism is treated beyond the usual collinear approximation. A major advantage of this model consists in a rather simple fitting procedur...

Enhanced biotic and abiotic transformation of Cr(vi) by quinone-reducing bacteria/dissolved organic matter/Fe(iii) in anaerobic environment.

Science.gov (United States)

Huang, Bin; Gu, Lipeng; He, Huan; Xu, Zhixiang; Pan, Xuejun

2016-09-14

This study investigated the simultaneous transformation of Cr(vi) via a closely coupled biotic and abiotic pathway in an anaerobic system of quinone-reducing bacteria/dissolved organic matters (DOM)/Fe(iii). Batch studies were conducted with quinone-reducing bacteria to assess the influences of sodium formate (NaFc), electron shuttling compounds (DOM) and the Fe(iii) on Cr(vi) reduction rates as these chemical species are likely to be present in the environment during in situ bioremediation. Results indicated that the concentration of sodium formate and anthraquinone-2-sodium sulfonate (AQS) had apparently an effect on Cr(vi) reduction. The fastest decrease in rate for incubation supplemented with 5 mM sodium formate and 0.8 mM AQS showed that Fe(iii)/DOM significantly promoted the reduction of Cr(vi). Presumably due to the presence of more easily utilizable sodium formate, DOM and Fe(iii) have indirect Cr(vi) reduction capability. The coexisting cycles of Fe(ii)/Fe(iii) and DOM(ox)/DOM(red) exhibited a higher redox function than the individual cycle, and their abiotic coupling action can significantly enhance Cr(vi) reduction by quinone-reducing bacteria.

Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy

Science.gov (United States)

Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.

2003-01-01

Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

Magnetic features of Fe-Cr-Co alloys with tailoring chromium content fabricated by spark plasma sintering

International Nuclear Information System (INIS)

Rastabi, Reza Amini; Ghasemi, Ali; Tavoosi, Majid; Ramazani, Mazaher

2017-01-01

Structural and magnetic characterization of Fe-Cr-Co alloys during milling, annealing and consolidation processes was the goal of this study. In this regards, different powder mixtures of Fe 80−x Cr x Co 20 (15≤x≤35) were mechanically milled in a planetary ball mill and then were consolidated by spark plasma sintering (SPS). The produced samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). According to achieved results, the structure of as-milled samples in different compositions consists of single α phase solid solution with coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The magnetic properties of consolidated samples depend on the kinds of formed precipitates in microstructure and the maximum values of coercive force and saturation of magnetization obtained in Fe 55 Cr 25 Co 20 magnetic (with single α phase) alloy were 107 Oe and Ms 172 emu/g, respectively. In fact, the formation of non-magnetic σ and γ phases has a destructive effect on magnetic properties of consolidated samples with higher Cr content. Since such magnet requires less cobalt, and contains similar magnetic feature with superior ductility compare to the AlNiCo 5, it could be considered as a promising candidate for employing instead of AlNiCo 5. - Highlights: • Milled samples consist of single phase α-solid solution. • Saturation of magnetization of Fe 65 Cr 15 Co 20 reached to 172 emu/g. • Fe 65 Cr 15 Co 20 alloy is the suitable composition fabricated by SPS.

Magnetic properties of the CrMnFeCoNi high-entropy alloy

International Nuclear Information System (INIS)

Schneeweiss, Oldřich; Friák, Martin; Masaryk University, Brno; Dudová, Marie; Holec, David

2017-01-01

In this paper, we present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ± 0.001 emu T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μ B ), while the local moments of Ni atoms effectively vanish. Finally, these results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

Evaluation on the Effect of Composition on Radiation Hardening and Embrittlement in Model FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Edmondson, Philip [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hu, Xunxiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Littrell, Kenneth C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howard, Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parish, Chad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-18

This report details the findings of post-radiation mechanical testing and microstructural characterization performed on a series of model and commercial FeCrAl alloys to assist with the development of a cladding technology with enhanced accident tolerance. The samples investigated include model alloys with simple ferritic grain structure and two commercial alloys with minor solute additions. These samples were irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to nominal doses of 7.0 dpa near or at Light Water Reactor (LWR) relevant temperatures (300-400 C). Characterization included a suite of techniques including small angle neutron scattering (SANS), atom probe tomography (APT), and transmission based electron microscopy techniques. Mechanical testing included tensile tests at room temperature on sub-sized tensile specimens. The goal of this work was to conduct detailed characterization and mechanical testing to begin establishing empirical and/or theoretical structure-property relationships for radiation-induced hardening and embrittlement in the FeCrAl alloy class. Development of such relationships will provide insight on the performance of FeCrAl alloys in an irradiation environment and will enable further development of the alloy class for applications within a LWR environment. A particular focus was made on establishing trends, including composition and radiation dose. The report highlights in detail the pertinent findings based on this work. This report shows that radiation hardening in the alloys is primarily composition dependent due to the phase separation in the high-Cr FeCrAl alloys. Other radiation induced/enhanced microstructural features were less dependent on composition and when observed at low number densities, were not a significant contributor to the observed mechanical responses. Pre-existing microstructure in the alloys was found to be important, with grain boundaries and pre-existing dislocation

Impact of neutron irradiation on mechanical performance of FeCrAl alloy laser-beam weldments

Science.gov (United States)

Gussev, M. N.; Cakmak, E.; Field, K. G.

2018-06-01

Oxidation-resistant iron-chromium-aluminum (FeCrAl) alloys demonstrate better performance in Loss-of-Coolant Accidents, compared with austenitic- and zirconium-based alloys. However, further deployment of FeCrAl-based materials requires detailed characterization of their performance under irradiation; moreover, since welding is one of the key operations in fabrication of light water reactor fuel cladding, FeCrAl alloy weldment performance and properties also should be determined prior to and after irradiation. Here, advanced C35M alloy (Fe-13%Cr-5%Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions were characterized after neutron irradiation in Oak Ridge National Laboratory's High Flux Isotope Reactor at 1.8-1.9 dpa in a temperature range of 195-559 °C. Specimen sets included as-received (AR) materials and specimens after controlled laser-beam welding. Tensile tests with digital image correlation (DIC), scanning electron microscopy-electron back scatter diffraction analysis, fractography, and x-ray tomography analysis were performed. DIC allowed for investigating local yield stress in the weldments, deformation hardening behavior, and plastic anisotropy. Both AR and welded material revealed a high degree of radiation-induced hardening for low-temperature irradiation; however, irradiation at high-temperatures (i.e., 559 °C) had little overall effect on the mechanical performance.

YSZ-based sensor using Cr-Fe-based spinel-oxide electrodes for selective detection of CO.

Science.gov (United States)

Anggraini, Sri Ayu; Fujio, Yuki; Ikeda, Hiroshi; Miura, Norio

2017-08-22

A selective carbon monoxide (CO) sensor was developed by the use of both of CuCrFeO 4 and CoCrFeO 4 as the sensing electrode (SE) for yttria-stabilized zirconia (YSZ)-based potentiometric sensor. The sensing-characteristic examinations of the YSZ-based sensors using each of spinel oxides as the single-SE sensor showed that CuCrFeO 4 -SE had the ability to detect CO, hydrocarbons and NO x gases, while CoCrFeO 4 -SE was sensitive to hydrocarbons and NO x gases. Thus, when both SEs were paired as a combined-SEs sensor, the resulting sensor could generate a selective response to CO at 450 °C under humid conditions. The sensor was also capable of detecting CO in the concentration range of 20-700 ppm. Its sensing mechanism that was examined via polarization-curve measurements was confirmed to be based on mixed-potential model. The CO response generated by the combined-SEs sensor was unaffected by the change of water vapor concentration in the range of 1.3-11.5 vol% H 2 O. Additionally, the sensing performance was stable during 13 days tested. Copyright © 2017 Elsevier B.V. All rights reserved.

X-ray imaging of the Cr and Fe lines from Cassiopeia A

NARCIS (Netherlands)

Maeda, Y.; Sato, T.; Tsunemi, H.; Bamba, A.; Vink, J.; Terada, Y.; Takeda, T.; Sawada, M.; Gandhi, P.; Matsumoto, H.; Uchiyama, Y.; Helder, E.A.; Hiraga, J.; Hughes, J.P.; Kokubun, M.; Tamagawa, T.; Tsuboi, Y.; Ishida, M.; Petre, R.; Mitsuda, K.

2014-01-01

Follow-up Suzaku X-ray observations of a young supernova remnant Cassiopeia A carried out with a long exposure of ˜ 165 ksec in 2012. Owing to the high statistics of the data, the map of Cr-K line is made. The flux map of Cr-K line is similar to that of Fe-K. The similarity indicates that the

Oxidation of Cr(III)-Fe(III) Mixed-phase Hydroxides by Chlorine: Implications on the Control of Hexavalent Chromium in Drinking Water.

Science.gov (United States)

Chebeir, Michelle; Liu, Haizhou

2018-05-17

The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation. Data showed that an increase in Fe(III) molar content resulted in a significant decrease in the stoichiometric Cr(VI) yield and the rate of Cr(VI) formation, mainly due to chlorine decay induced by Fe(III) surface sites. An increase in bicarbonate enhanced the rate of Cr(VI) formation, likely due to the formation of Fe(III)-carbonato surface complexes that slowed down the scavenging reaction with chlorine. The presence of bromide significantly accelerated the oxidation of FexCr(1-x)(OH)3(s) by chlorine, resulting from the catalytic effect of bromide acting as an electron shuttle. A higher solution pH between 6 and 8.5 slowed down the oxidation of Cr(III) by chlorine. These findings suggested that the oxidative conversion of chromium-containing iron corrosion products in drinking water distribution systems can lead to the occurrence of Cr(VI) at the tap, and the abundance of iron, and a careful control of pH, bicarbonate and bromide levels can assist the control of Cr(VI) formation.

Effects of Additives on the Corrosion Resistance of Iron Aluminides(Fe-38at.%AI-5at.%Cr)

International Nuclear Information System (INIS)

Choi, H. C.; Kim, C. W.; Joo, S. M.; Choi, D. C.; Kim, K. H.

2001-01-01

The effects of additives on the corrosion resistance of iron aluminides(Fe-38at.%AI-5at.%Cr) were investigated using potentiostat. The specimens were cast by vacuum arc melting. The subsequent homogenization was carried out in Ar gas atmosphere at 1000 .deg. C for 7 days. The corroded surfaces of the tested specimens were observed using an optical microscope and a scanning electron microscope(SEM) after electrochemical tests were carried out in various solutions. While the Hf addition to Fe-38at.%AI-5at.%Cr resulted in equiaxial microstructure, the Zr addition resulted in dendritic microstructure. However, no change in microstructure was observed when Mo was added. The addition of Mo to Fe-38at.%AI-5at.%Cr intermetallic compound was found to increase the pitting potential, which improved the resistance against the pitting corrosion attack. The addition of Hf and Zr resulted in a higher activation current density and a lower pitting potential. These results may indicate that the dendrite structure played a major role in decreasing the pitting corrosion resistance of Fe-38at.%AI-5at%Cr intermetallic compound. The Mo addition to Fe-38at.%AI-5at.%Cr decreased the number and size of pits. In the case of Zr addition, the pits nucleated and grew remarkably at dendritic branches

Slurry Erosion Behavior of AlxCoCrFeNiTi0.5 High-Entropy Alloy Coatings Fabricated by Laser Cladding

Directory of Open Access Journals (Sweden)

Jianhua Zhao

2018-02-01

Full Text Available High-entropy alloys (HEAs have gained extensive attention due to their excellent properties and the related scientific value in the last decade. In this work, AlxCoCrFeNiTi0.5 HEA coatings (x: molar ratio, x = 1.0, 1.5, 2.0, and 2.5 were fabricated on Q345 steel substrate by laser-cladding process to develop a practical protection technology for fluid machines. The effect of Al content on their phase evolution, microstructure, and slurry erosion performance of the HEA coatings was studied. The AlxCoCrFeNiTi0.5 HEA coatings are composed of simple face-centered cubic (FCC, body-centered cubic (BCC and their mixture phase. Slurry erosion tests were conducted on the HEA coatings with a constant velocity of 10.08 m/s and 16–40 meshs and particles at impingement angles of 15, 30, 45, 60 and 90 degrees. The effect of three parameters, namely impingement angle, sand concentration and erosion time, on the slurry erosion behavior of AlxCoCrFeNiTi0.5 HEA coatings was investigated. Experimental results show AlCoCrFeNiTi0.5 HEA coating follows a ductile erosion mode and a mixed mode (neither ductile nor brittle for Al1.5CoCrFeNiTi0.5 HEA coating, while Al2.0CoCrFeNiTi0.5 and Al2.5CoCrFeNiTi0.5 HEA coatings mainly exhibit brittle erosion mode. AlCoCrFeNiTi0.5 HEA coating has good erosion resistance at all investigated impingement angles due to its high hardness, good plasticity, and low stacking fault energy (SFE.

Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

Science.gov (United States)

Steeves, A.F.; Bibb, A.E.

A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

Si effects on radiation induced segregation in high purity Fe-18Cr-14Ni alloys irradiated by Ni ions

International Nuclear Information System (INIS)

Ohta, Joji; Kako, Kenji; Mayuzumi, Masami; Kusanagi, Hideo; Suzuki, Takayoshi

1999-01-01

To illustrate the effects of the element Si on radiation induced segregation, which causes irradiation assisted stress corrosion cracking (IASCC), we investigated grain boundary chemistry of high purity Fe-18Cr-14Ni-Si alloys irradiated by Ni ions using FE-TEM. The addition of Si up to 1% does not affect the Cr depletion at grain boundaries, while it slightly enhances the depletion of Fe and the segregation of Ni and Si. The addition of 2% Si causes the depletion of Cr and Fe and the segregation of Ni and Si at grain boundaries. Thus, the Si content should be as low as possible. In order to reduce the depletion of Cr at grain boundaries, which is one of the major causes of IASCC, Si content should be less than 1%. (author)

Polyethylenimine functionalized Fe3O4/steam-exploded rice straw composite as an efficient adsorbent for Cr(VI) removal

Science.gov (United States)

Zhang, Shengli; Wang, Zhikai; Chen, Haoyu; Kai, Chengcheng; Jiang, Man; Wang, Qun; Zhou, Zuowan

2018-05-01

Polyethyleneimine functionalized Fe3O4/steam-exploded rice straw composite (Fe3O4-PEI-SERS), which combines magnetic separation with adsorption of PEI functionalized biosorbent, was successfully prepared via a simple glutaraldehyde crosslinking method. Its adsorption potential for the removal of Cr(VI) was systematically studied in batch mode. Results showed that Cr(VI) adsorption on Fe3O4-PEI-SESERS was highly pH-dependent, and the optimum pH was 2.0. The time to reach equilibrium was related to initial Cr(VI) concentration and was 1 and 6 h for 200 and 300 mg/L of Cr(VI), respectively. The adsorption system followed pseudo-second-order kinetic model and Langmuir isotherm. Its maximum adsorption capacity was 280.11, 317.46 and 338.98 mg/g at 25, 35 and 45 °C, respectively. The competitive uptake from coexisting ions (K+, Na+, Cu2+, Cl- and NO3-) was insignificant except SO42-. After six adsorption/desorption cycles, the adsorbent retained good adsorption capacity. The Cr(VI) removal involved its partial reduction into Cr(III). Due to the properties of high adsorption capacity, strong magnetic responsiveness, good reusability and Cr(VI) detoxification, the Fe3O4-PEI-SESERS has a potential application in Cr(VI) removal from wastewater.

Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAl alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed

Oxygen-induced immediate onset of the antiferromagnetic stacking in thin Cr films on Fe(001)

Energy Technology Data Exchange (ETDEWEB)

Berti, Giulia, E-mail: giulia.berti@polimi.it; Brambilla, Alberto; Calloni, Alberto; Bussetti, Gianlorenzo; Finazzi, Marco; Duò, Lamberto; Ciccacci, Franco [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2015-04-20

We investigated the magnetic coupling of ultra-thin Cr films grown at 600 K on a Fe(001)-p(1 × 1)O substrate by means of spin-polarized photoemission spectroscopy. Our findings show that the expected antiferromagnetic stacking of the magnetization in Cr(001) layers occurs right from the first atomic layer at the Cr/Fe interface. This is at variance with all previous observations in similar systems, prepared in oxygen-free conditions, which always reported on a delayed onset of the magnetic oscillations due to the occurrence of significant chemical alloying at the interface, which is substantially absent in our preparation.

Doping effects on structural and magnetic properties of Heusler alloys Fe2Cr1-xCoxSi

Science.gov (United States)

Liu, Yifan; Ren, Lizhu; Zheng, Yuhong; He, Shikun; Liu, Yang; Yang, Ping; Yang, Hyunsoo; Teo, Kie Leong

2018-05-01

In this work, 30nm Fe2Cr1-xCoxSi (FCCS) magnetic films were deposited on Cr buffered MgO (100) substrates by sputtering. Fe2Cr0.5Co0.5Si exhibits the largest magnetization and optimal ordered L21 cubic structure at in-situ annealing temperature (Tia) of 450°C. The Co composition dependence of crystalline structures, surface morphology, defects, lattice distortions and their correlation with the magnetic properties are analyzed in detail. The Co-doped samples show in-plane M-H loops with magnetic squareness ratio of 1 and increasing anisotropy energy density with Co composition. Appropriate Co doping composition promotes L21 phase but higher Co composition converts L21 to B2 phase. Doping effect and lattice mismatch both are proved to increase the defect density. In addition, distortions of the FCCS lattice are found to be approximately linear with Co composition. The largest lattice distortion (c/a) is 0.969 for Fe2Cr0.25Co0.75Si and the smallest is 0.983 for Fe2CrSi. Our analyses suggest that these tetragonal distortions mainly induced by an elastic stress from Cr buffer account for the large in-plane anisotropy energy. This work paves the way for further tailoring the magnetic and structural properties of quaternary Heusler alloys.

Final report on in-reactor uniaxial tensile deformation of pure iron and Fe-Cr alloy

International Nuclear Information System (INIS)

Singh, B.N.; Xiaoxu Huang; Taehtinen, S.; Moilamen, P.; Jacquet, P.; Dekeyser, J.

2007-11-01

Traditionally, the effect of irradiation on mechanical properties of metals and alloys is determined using post-irradiation tests carried out on pre-irradiated specimens and in the absence of irradiation environment. The results of these tests may not be representative of deformation behaviour of materials used in the structural components of a fission or fusion reactor where the materials will be exposed concurrently to displacement damage and external and/or internal stresses. In an effort to evaluate and understand the dynamic response of materials under these conditions, we have recently performed a series of uniaxial tensile tests on Fe-Cr and pure iron specimens in the BR-2 reactor at Mol (Belgium). The present report first provides a brief description of the test facilities and the procedure used for performing the in-reactor tests. The results on the mechanical response of materials during these tests are presented in the form of stress-displacement dose and the conventional stress-strain curves. For comparison, the results of post-irradiation tests and tests carried out on unirradiated specimens are also presented. Results of microstructural investigations on the unirradiated and deformed, irradiated and undeformed, post-irradiation deformed and the in-reactor deformed specimens are also described. During the in-reactor tests the specimens of both Fe-Cr alloy and pure iron deform in a homogeneous manner and do not exhibit the phenomenon of yield drop. An increase in the pre-yield dose increases the yield stress but not the level of maximum flow stress during the in-reactor deformation of Fe-Cr alloy. Neither the in-reactor nor the post-irradiation deformed specimens of Fe-Cr alloy and pure iron showed any evidence of cleared channel formation. Both in Fe-Cr and pure iron, the in-reactor deformation leads to accumulation of dislocations in a homogeneous fashion and only to a modest density. No dislocation cells are formed during the in-reactor or post

Microstructure and High Temperature Oxidation Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Powder Injection Molding Process

Science.gov (United States)

Joo, Yeun-Ah; Kim, Young-Kyun; Yoon, Tae-Sik; Lee, Kee-Ahn

2018-03-01

This study investigated the microstructure and high temperature oxidation property of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding process. Observations of initial microstructure showed a unique structure where α-Fe and (Cr, Fe)2B form a continuous three-dimensional network. High temperature oxidation tests were performed at 900, 1000 and 1100 °C, for 24 h, and the oxidation weight gain according to each temperature condition was 0.13, 0.84 and 6.4 mg/cm2, respectively. The oxidation results according to time at 900 and 1000 °C conditions represented parabolic curves, and at 1100 °C condition formed a rectilinear curve. Observation and phase analysis results of the oxides identified Cr2O3 and SiO2 at 900 and 1000 °C. In addition to Cr2O3 and SiO2, CrBO3 and FeCr2O4 formed due to phase decomposition of boride were identified at 1100 °C. Based on the findings above, this study suggested the high temperature oxidation mechanism of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding, and the possibility of its application as a high temperature component material was also discussed.

Magnetic features of Fe-Cr-Co alloys with tailoring chromium content fabricated by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Rastabi, Reza Amini; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid; Ramazani, Mazaher

2017-03-15

Structural and magnetic characterization of Fe-Cr-Co alloys during milling, annealing and consolidation processes was the goal of this study. In this regards, different powder mixtures of Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) were mechanically milled in a planetary ball mill and then were consolidated by spark plasma sintering (SPS). The produced samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). According to achieved results, the structure of as-milled samples in different compositions consists of single α phase solid solution with coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The magnetic properties of consolidated samples depend on the kinds of formed precipitates in microstructure and the maximum values of coercive force and saturation of magnetization obtained in Fe{sub 55}Cr{sub 25}Co{sub 20} magnetic (with single α phase) alloy were 107 Oe and Ms 172 emu/g, respectively. In fact, the formation of non-magnetic σ and γ phases has a destructive effect on magnetic properties of consolidated samples with higher Cr content. Since such magnet requires less cobalt, and contains similar magnetic feature with superior ductility compare to the AlNiCo 5, it could be considered as a promising candidate for employing instead of AlNiCo 5. - Highlights: • Milled samples consist of single phase α-solid solution. • Saturation of magnetization of Fe{sub 65}Cr{sub 15}Co{sub 20} reached to 172 emu/g. • Fe{sub 65}Cr{sub 15}Co{sub 20} alloy is the suitable composition fabricated by SPS.

Connection between twinning and brittle fracture in Fe-Cr-Co-Mo crystals

International Nuclear Information System (INIS)

Kirillov, V.A.; Chumlyakov, Yu.I.; Korotaev, A.D.; Aparova, L.A.

1989-01-01

Plasticity dependence on crystal orientation, on deformation temperature and structure state of alloy is investigated in Fe-28 % Cr-10 % Co-2 % Mo (at. %) monocrystals. Isostructure decomposition results in increase of critical shearing stresses τ cr , in change of deformation mechanism from slipping into twinning and abrupt reduction of plasticity. Brittleness - ductility transition is detected in high-stable structure states τ cr >280 MPa. Explanation of plasticity abrupt reduction of high-stable crystals using estimation of change of deformation mechanism and of deforming stress high level is given

Recyclable magnetic photocatalysts of Fe2+/TiO2 hierarchical architecture with effective removal of Cr(VI) under UV light from water

International Nuclear Information System (INIS)

Xu, S.C.; Zhang, Y.X.; Pan, S.S.; Ding, H.L.; Li, G.H.

2011-01-01

Highlights: ► Fe 2+ /TiO 2 catalyst has a three-level hierarchical architecture. ► With a removal effectiveness of 99.3% at Cr(VI) concentration of 10 mg L −1 . ► Two-step reduction: TiO 2 photoreduces Fe 2+ to Fe and Fe reduces Cr(VI) to Cr(III). ► Hierarchical architecture serves as both photocatalytic reactor and absorbent. ► Fe 2+ /TiO 2 catalyst can be magnetically separated from wastewater and recycled. - Abstract: We report the synthesis and photocatalytic removal of Cr(VI) from water of hierarchical micro/nanostructured Fe 2+ /TiO 2 tubes. The TiO 2 tubes fabricated by a facile solvothermal approach show a three-level hierarchical architecture assembled from dense nanosheets nearly vertically standing on the surface of TiO 2 microtube. The nanosheets with a thickness of about 20 nm are composed of numerous TiO 2 nanocrystals with size in the range of 15–20 nm. Ferrous ions are doped into the hierarchical architecture by a reduction route. The Fe 2+ /TiO 2 catalyst demonstrates an effective removal of Cr(VI) from water under UV light and the removal effectiveness reaches 99.3% at the initial Cr(VI) concentration of 10 mg L −1 . The ferrous ion in the catalyst serves not as the photo-electron trap but as an intermedium of a two-step reduction. The TiO 2 photoreduces the Fe 2+ ions to Fe atoms firstly, then the Fe atoms reduce the Cr(VI) to Cr(III), and the later is removed by adsorption. The hierarchical architecture of the catalyst serves as a reactor for the photocatalytic reaction of Cr(VI) ions and an effective absorbent for the removal of Cr(III) ions. The catalyst can be easily magnetically separated from the wastewater after photocatalytic reaction and recycled after acid treatment.

Anomalously large ferromagnetic resonance linewidth in the Gd/Cr/Fe film plane

Science.gov (United States)

Sun, Li; Zhang, Wen; Wong, Ping Kwan Johnny; Yin, Yuli; Jiang, Sheng; Huang, Zhaocong; Zhai, Ya; Yao, Zhongyu; Du, Jun; Sui, Yunxia; Zhai, Hongru

2018-04-01

As an important parameter for characterizing the magnetization dynamics, Gilbert damping constant α in a thin film or a multilayer is generally extracted from the linear fitting of the frequency-dependence of the ferromagnetic resonance linewidth, sometimes accompanied with a tiny deviation of the linewidth to a smaller value at the low-frequency or high-frequency region due to the two-magnon scattering with an in-plane-field configuration, in which an in-plane magnetic field H perpendicular to a microwave field h was applied in film plane during measurement. In contrast, here we report, in ultrathin Gd/Cr/Fe multilayers, an anomalously large linewidth in the film plane at the low-frequency region. For the first time, we have successfully extracted the Gilbert damping constant from perfect theoretical fitting to the experimental data, by considering the effective direction of the magnetization around in precession staying out of the film plane when the in-pane H at which the precession starts is below the saturation field. This magnetization deviation from the film plane is found to have an obvious contribution to the enhanced linewidth caused by two magnon scattering, while slightly reduce the intrinsic linewidth. Under the same resonance frequency, the deviation angle reaches the maximum values at tCr = 1.0 nm while decreases when tCr increases to 1.5 nm, which coincides with the trend of the surface perpendicular anisotropy constant K⊥. A reduced intrinsic damping constant α is obtained as the introduction of Gd layer and Cr layer as a result of the competition between the spin pumping effect and the interfacial effects at the Fe/Gd and Fe/Cr interfaces. While the decreasing α for film with Cr layer thickness increasing to 1.5 nm might means the contribution of the electron density of states at the Fermi energy n(EF). This study offers an effective way to accurately obtain the intrinsic damping constant of spintronic materials/devices, which is essential

Study of the effect of short ranged ordering on the magnetism in FeCr alloys

Energy Technology Data Exchange (ETDEWEB)

Jena, Ambika Prasad, E-mail: apjena@bose.res.in [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India); Sanyal, Biplab, E-mail: biplab.sanyal@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Mookerjee, Abhijit, E-mail: abhijit.mookerjee61@gmail.com [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India)

2014-01-15

For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied.

Study of the effect of short ranged ordering on the magnetism in FeCr alloys

International Nuclear Information System (INIS)

Jena, Ambika Prasad; Sanyal, Biplab; Mookerjee, Abhijit

2014-01-01

For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied

Positron annihilation study of the vacancy clusters in ODS Fe-14Cr alloys

Science.gov (United States)

Domínguez-Reyes, R.; Auger, M. A.; Monge, M. A.; Pareja, R.

2017-04-01

Oxide dispersion strengthened Fe14Cr and Fe14CrWTi alloys produced by mechanical alloying and hot isostatic pressing were subjected to isochronal annealing up to 1400 °C, and the evolution and thermal stability of the vacancy-type defects were investigated by positron annihilation spectroscopy (PAS). The results were compared to those from a non-oxide dispersion strengthened Fe14Cr alloy produced by following the same powder metallurgy route. The long lifetime component of the PAS revealed the existence of tridimensional vacancy clusters, or nanovoids, in all these alloys. Two recovery stages are found in the oxide dispersion strengthened alloys irrespective of the starting conditions of the samples. The first one starting at T > 750 °C is attributed to thermal shrinkage of large vacancy clusters, or voids. A strong increase in the intensity of the long lifetime after annealing at temperatures in the 800-1050 °C range indicates the development of new vacancy clusters. These defects appear to be unstable above 1050 °C, but some of them remain at temperatures as high as 1400 °C, at least for 90 min.

The helium effect at grain boundaries in Fe-Cr alloys: A first-principles study

Energy Technology Data Exchange (ETDEWEB)

Zemła, M.R., E-mail: marcin.zemla@wimpw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Wróbel, J.S.; Wejrzanowski, T. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland)

2017-02-15

Helium is produced in the structural materials in nuclear power plants by nuclear transmutation following neutron irradiation. Since the solubility of helium in all metals is extremely low, helium tends to be trapped at defects such as vacancies, dislocations and grain boundaries, which cause material embrittlement. Density functional theory (DFT) calculations were performed in order to investigate the helium effect at grain boundaries (GBs) in iron-chromium alloys. Both cohesive energy and magnetic properties at symmetric Σ3(1 1 1) and Σ5(2 1 0) tilt Fe GBs are studied in the presence of Cr and He atoms. It is found that the presence of Cr atoms increases cohesive energy, at different He concentrations, and strongly influences magnetic properties at the GBs. The effect of the segregation energy of helium atom as a function of the different positions of Cr atoms located inside/outside a GB has been considered. Results of the present first-principles study enable one to clarify the role of Cr in understanding the helium effect in Fe-Cr-based alloys.

Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

Science.gov (United States)

Pang, Q.; Hu, Z. L.; Wu, G. H.

2016-12-01

Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

STUDY OF COATINGS OBTAINED FROM ALLOY Fe-Mn-C-B-Si-Ni-Cr

Directory of Open Access Journals (Sweden)

Mychajło Paszeczko

2016-09-01

Full Text Available Tribological behaviour of coatings obtained from eutectic alloy Fe-Mn-C-B-Si-Ni-Cr was studied. The coatings were obtained by the method of gas metal arc welding (GMA with use of powder wire. GMA welding method is widely used for the regeneration of machine parts. Eutectic Fe-Mn-C-B-Si-Ni-Cr alloys can be used to obtain high quality coatings resistant to wear and corrosion. Pin-on-disk dry sliding wear tests at sliding speeds 0.4 m/s and under load 10 MPa were conducted for pin specimens. During friction a typical tribological behavior was observed. The mechanism of wear was mechanical-chemical.

FeCrO Nanoparticles as Anode Catalyst for Ethane Proton Conducting Fuel Cell Reactors to Coproduce Ethylene and Electricity

Directory of Open Access Journals (Sweden)

Jian-Hui Li

2011-01-01

Full Text Available Ethylene and electrical power are cogenerated in fuel cell reactors with FeCr2O4 nanoparticles as anode catalyst, La0.7Sr0.3FeO3- (LSF as cathode material, and BaCe0.7Zr0.1Y0.2O3- (BCZY perovskite oxide as proton-conducting ceramic electrolyte. FeCr2O4, BCZY and LSF are synthesized by a sol-gel combustion method. The power density increases from 70 to 240 mW cm−2, and the ethylene yield increases from about 14.1% to 39.7% when the operating temperature of the proton-conducting fuel cell reactor increases from 650∘C to 750∘C. The FeCr2O4 anode catalyst exhibits better catalytic performance than nanosized Cr2O3 anode catalyst.

X-ray photoemission spectroscopy investigation of the early stages of the oxygen aided Cr growth on Fe(0 0 1)

Energy Technology Data Exchange (ETDEWEB)

Brambilla, A., E-mail: alberto.brambilla@polimi.it [CNISM and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Calloni, A.; Picone, A.; Finazzi, M.; Duò, L.; Ciccacci, F. [CNISM and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy)

2013-02-15

We report on an X-ray photoemission spectroscopy investigation of the early stages of growth of ultra-thin Cr films on the oxygen-passivated Fe(0 0 1)–p(1 × 1)O surface. The Cr coverages ranged from sub-monolayer up to a few atomic layers. Cr has been grown either at 380 K or at 570 K. Our investigation reveals that during the Cr film growth oxygen floats toward the free surface. The presence of a metallic Cr signal from the very beginning of film growth is discussed in relation to Cr–Fe intermixing and alloy formation at the interface. Our findings are independent from the growth temperature, indicating that it has a very little influence on the chemical interactions at the interface, at variance with the oxygen-free Cr/Fe interface.

X-ray photoemission spectroscopy investigation of the early stages of the oxygen aided Cr growth on Fe(0 0 1)

International Nuclear Information System (INIS)

Brambilla, A.; Calloni, A.; Picone, A.; Finazzi, M.; Duò, L.; Ciccacci, F.

2013-01-01

We report on an X-ray photoemission spectroscopy investigation of the early stages of growth of ultra-thin Cr films on the oxygen-passivated Fe(0 0 1)–p(1 × 1)O surface. The Cr coverages ranged from sub-monolayer up to a few atomic layers. Cr has been grown either at 380 K or at 570 K. Our investigation reveals that during the Cr film growth oxygen floats toward the free surface. The presence of a metallic Cr signal from the very beginning of film growth is discussed in relation to Cr–Fe intermixing and alloy formation at the interface. Our findings are independent from the growth temperature, indicating that it has a very little influence on the chemical interactions at the interface, at variance with the oxygen-free Cr/Fe interface.

Evidence of formation of trans-Fe nuclei in Fe+Al interactions at 1.88 GeV using Cr-39 (DOP) detector

International Nuclear Information System (INIS)

Ganguly, A.K.; Chaudhuri, Biva

1991-01-01

A wedge-shaped aluminium target was irradiated with 1.88 A GeV Fe beam to study various features of Fe+Al nucleus-nucleus interaction and their dependence on target thickness. The detector employed was a stack of CR-39 (DOP) and Lexan plastic nuclear track detectors which have a characteristically high charge resolution property. To distinguish the actual events from background and buildup a selection criteria for easy and unambiguous rejection of unwanted interfering events the stack of detectors was placed at an angle of 60deg with respect to the beam. After irradiation the CR-39 (DOP) detectors were etched and the elliptic etch-pit diameters were scanned. The diameter distribution of the elliptic etch-pits exhibits the existence of trans Fe nuclei. The production of trans Fe fraction is seen to increase with the thickness of the aluminium target. The possible causes of this increase are being investigated. (author). 12 refs., 4 figs

Structural, thermal and photomagnetic properties of spin crossover [Fe(bpp)2]2+ salts bearing [Cr(L)(ox)2]- anions.

Science.gov (United States)

Clemente-León, Miguel; Coronado, Eugenio; Giménez-López, M Carmen; Romero, Francisco M; Asthana, Saket; Desplanches, Cédric; Létard, Jean-François

2009-10-14

This paper is divided into two parts: in the first part, the influence of solvate molecules on the magnetic properties of spin crossover salts of [Fe(bpp)(2)][Cr(L)(ox)(2)]ClO(4) x nS (bpp = 2,6-bis(pyrazol-3yl)pyridine; L = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen); ox = oxalate dianion; S = solvent) is analyzed. The second part is devoted to the photomagnetic properties of the previously reported [Fe(bpp)(2)][Cr(L)(ox)(2)](2) family of compounds. The study describes the crystal structure, differential scanning calorimetry (DSC) and magnetic properties of [Fe(bpp)(2)][Cr(bpy)(ox)(2)]ClO(4) x EtOH x 4 H(2)O (1) and [Fe(bpp)(2)][Cr(phen)(ox)(2)]ClO(4) x 1.5 EtOH x 4 H(2)O (2). Both salts are high-spin (HS) compounds. Desolvation of 1 yields a material exhibiting a gradual spin crossover that involves 50% of the Fe(2+) cations. Rehydration of this desolvated salt induces a significant increase in the low-spin (LS) population. Desolvation of 2 affords a material showing a more abrupt spin crossover with thermal hysteresis (T(1/2)(increasing) = 286 K and T(1/2)(decreasing) = 273 K). This material is not very sensitive to rehydration. The anhydrous compounds [Fe(bpp)(2)][Cr(bpy)(ox)(2)](2) (3) and [Fe(bpp)(2)][Cr(phen)(ox)(2)](2) (4) display some quantitative photomagnetic conversion with T(LIESST) values of 41 and 51 K, respectively. Kinetic parameters governing the photo-induced HS-LS relaxation process have been determined and used to reproduce the T(LIESST) curves.

Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

Energy Technology Data Exchange (ETDEWEB)

Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

2016-12-15

Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

International Nuclear Information System (INIS)

Sarikaya, M.

1979-06-01

The effects of alloying elements and heat treatments on the microstructural changes and strength-toughness properties were investigated in optimization of vacuum melted Fe/Cr/C base steels. The structure of the steels in the as-quenched conditions consisted of highly dislocated autotempered lath martensite (strong phase) and thin continuous interlath films of retained austenite (tough phase). It has been emphasized again that the mechanical properties of the steels are sensitive to the amount and the stability of retained austenite. To increase the stability of retained austenite in the as-quenched condition 2 w/o Mn or 2 w/o Ni was added to the base steel, viz., Fe/3Cr/0.3C. Partial replacement of Cr by about 0.5 w/o Mo did not alter the beneficial microstructure

Study of the structural, electronic and magnetic properties of ScFeCrT (T=Si, Ge) Heusler alloys by first principles approach

Energy Technology Data Exchange (ETDEWEB)

Rasool, Muhammad Nasir [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Hussain, Altaf, E-mail: altafiub@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Javed, Athar, E-mail: athar.physics@pu.edu.pk [Department of Physics, University of the Punjab, Lahore 54590 (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan)

2017-03-15

Spin polarized structural, electronic, magnetic and bonding properties of ScFeCrT (T=Si, Ge) Heusler alloys are studied by employing density functional theory. The total energy calculation (for a static lattice) shows that both alloys are structurally stable in ferromagnetic phase with compressibility C{sub ScFeCrSi}>C{sub ScFeCrGe}. The electronic and band structure analysis show that the ScFeCrT alloys exhibit half-metallic ferromagnetic (HMF) behaviour for spin ↑ channel while semiconducting behaviour in spin ↓ channel. Both alloys exhibit total magnetic moment, M{sub Total}=3.0 µ{sub B}/cell obeying the Slater Pauling rule, M{sub SPR}=(N{sub v} –18)μ{sub B}. For ScFeCrSi and ScFeCrGe alloys, the charge density and interatomic bonding character show highly covalent and polar covalent character, respectively. For both alloys, 100% spin polarization (for spin ↑ state) is expected which is an indication of their suitability for applications in spintronic devices. - Highlights: • Heusler alloys ScFeCrT (T= Si, Ge) are studied by first principles approach. • Structural, electronic, magnetic and bonding properties are reported. • Both alloys show half-metallicity and ferromagnetic behaviour. • Combination of properties shows the suitability of alloys in spintronic devices.

Effect of dissolved hydrogen on Schottky barrier height of Fe-Cr alloy heterojunction

Science.gov (United States)

Berahim, A. N.; Zaharudin, M. Z.; Ani, M. H.; Arifin, S. K.

2018-01-01

The presence of water vapour at high temperature oxidation has certain effects on ferritic alloy in comparison to dry environment. It is hypothesized that at high temperature; water vapour provides hydrogen, which will dissolve into ferritic alloy substrate and altering their electronic state at the metal-oxide interface. This work aimed to clarify the change in electronic state of metal-oxide heterojunction with the presence of hydrogen/water vapour. In this study, the Schottky Barrier (SB) was created by sputtering Cr2O3 onto prepared samples by using RF Magnetron sputtering machine. The existence of Fe/Cr2O3 junction was characterized by using XRD. The surfaces were observed by using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The samples were then exposed in dry and humid condition at temperature of 473 K and 1073 K. In dry condition, 100% Ar is flown inside the furnace, while in wet condition mixture of 95% Ar and 5% H was used. I-V measurement of the junction was done to determine the Schottky Barrier Height(SBH) of the samples in the corresponding ambient. The results show that in Fe/Cr2O3 junction, with presence of hydrogen at temperature 473 K; the SBH was reduced by the scale factor of 1.054 and at 1073 K in wet ambient by factor of 1.068. Meanwhile, in Fe-Cr/Cr2O3 junction with presence of hydrogen, the value of SBH was increased by scale factor of 1.068 at temperature 473 K while at 1073 K, the SBH also increased by factor of 1.009.

Mechanical and fatigue properties of martensitic Fe-13Cr steel in contact with lead and lead-bismuth melts

Energy Technology Data Exchange (ETDEWEB)

Yaskiv, O.I., E-mail: oleh.yaskiv@ipm.lviv.ua; Fedirko, V.M.

2014-01-15

Highlights: •We investigated the influence of Pb and Pb-Bi melts on mechanical properties of Fe-13Cr steel at high temperatures. •We revealed the temperature interval of liquid metal embrittlement of Fe-13Cr steel. •Pb-Bi has more negative impact as compared with Pb for both plasticity and fatigue. -- Abstract: The influence of stagnant liquid-metal environments (Pb and Pb-Bi) on mechanical (strength and plasticity) and fatigue properties (low cycle fatigue) of martensitic Fe-13Cr steel in temperature interval of 250–600 °S have been investigated. Heavy liquid metals facilitate decreasing in ultimate strength by 10–20% against that in vacuum. The increase of temperature enhances this effect. Fe-13Cr steel is susceptible to liquid-metal embrittlement in the temperature interval of 350–450 °S, which manifests itself more substantially in lead-bismuth eutectic. The decrease of plasticity in Pb is 11% at 450 °S and in Pb-Bi is 30% in temperature interval 350–400 °S. Liquid metal environments significantly reduce fatigue life of Fe-13Cr steel. Pb-Bi has a more negative impact. In particular, with increasing total strain amplitude (up to 1.0%), the decrease in the cycle number to fracture by more than two orders of magnitude occurs.

Influence of an external magnetic field on damage by self-ion irradiation in Fe90Cr10 alloy

Directory of Open Access Journals (Sweden)

Fernando José Sánchez

2016-12-01

Full Text Available The effect of an external magnetic field (B=0.5 T on Fe90Cr10 specimens during Fe ion irradiation, has been investigated by means of Conversion Electron Mössbauer Spectroscopy (CEMS. The analysis has revealed significant differences in the average hyperfine magnetic field (=0.3 T between non-irradiated and irradiated samples as well as between irradiations made with B (w/ B and without B (w/o B. It is considered that these variations can be due to changes in the local environment around the probe nuclei (57Fe; where vacancies and Cr distribution play a role. The results indicate that the Cr distribution in the neighbourhood of the iron atoms could be changed by the application of an external field. This would imply that an external magnetic field may be an important parameter to take into account in predictive models for Cr behaviour in Fe–Cr alloys, and especially in fusion conditions where intense magnetic fields are required for plasma confinement.

Electronic structure of Cr doped Fe3O4 thin films by X-ray absorption near-edge structure spectroscopy

Science.gov (United States)

Chen, Chi-Liang; Dong, Chung-Li; Asokan, Kandasami; Chern, G.; Chang, C. L.

2018-04-01

Present study reports the electronic structures of Cr doped Fe3O4 (Fe3-xCrxO4 (0 ≤ x ≤ 3) grown on MgO (100) substrates in the form of thin films fabricated by a plasma-oxygen assisted Molecular Beam Epitaxy (MBE). X-ray absorption near-edge structure (XANES) spectra at Cr & Fe L-, and O K-edges were used to understand the electronic structure: changes in the bonding nature, valence states, and site occupancies. Cr doping in Fe3O4 results in the change of charge transfer, crystal structure, and selective occupation of ions in octahedral and tetrahedral sites. Such change modifies the electrical and magnetic properties due to the covalency of Cr ions. The physical and chemical properties of ferrites are strongly dependent on the lattice site, ion size of dopant, and magnetic nature present at different structural symmetry of the spinel structure.

Alloying behavior, microstructure and mechanical properties in a FeNiCrCo0.3Al0.7 high entropy alloy

International Nuclear Information System (INIS)

Chen, Weiping; Fu, Zhiqiang; Fang, Sicong; Xiao, Huaqiang; Zhu, Dezhi

2013-01-01

Highlights: • FeNiCrCo 0.3 Al 0.7 high entropy alloy is prepared via MA and SPS. • Two BCC phases and one FCC phase were obtained after SPS. • The two BCC phases are enriched in Fe–Cr (A2 structure) and enriched in Ni–Al (B2 structure). • Bulk FeNiCrCo 0.3 Al 0.7 HEA exhibits excellent mechanical properties. - Abstract: The present paper reports the synthesis of FeNiCrCo 0.3 Al 0.7 high entropy alloy (HEA) by mechanical alloying (MA) and spark plasma sintering (SPS) process. Alloying behavior, microstructure, mechanical properties and detailed phases of the alloy were investigated systematically. During MA, the formation of a supersaturated solid solution with body-centered cubic (BCC) structure occurred. However, partial BCC structure phase transformed into a face-center cubic (FCC) structure phase during SPS. Two BCC phases with nearly the same lattice parameter of 3.01 Å and one FCC phase with the lattice parameter of 3.72 Å were characterized in the transmission electron microscope (TEM) images. The two BCC phases which are evidently deviated from the definition of high entropy alloys (HEAs) are enriched in Fe–Cr and enriched in Ni–Al, respectively. Moreover, the FCC phase agrees well with the definition of HEAs. Bulk FeNiCrCo 0.3 Al 0.7 alloy with little porosity exhibits much better mechanical properties except compression ratio compared with other typical HEAs of FeNiCrCoAl HEA system. The yield strength, compressive strength, compression ratio and Vickers hardness of FeNiCrCo 0.3 Al 0.7 alloy are 2033 ± 41 MPa, 2635 ± 55 MPa, 8.12 ± 0.51% and 624 ± 26H v , respectively. The fracture mechanism of bulk FeNiCrCo 0.3 Al 0.7 alloy is dominated by intercrystalline fracture and quasi-cleavage fracture

Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

Energy Technology Data Exchange (ETDEWEB)

Wang, Qiang [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Huang, Liping, E-mail: lipinghuang@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Pan, Yuzhen [College of Chemistry, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Li Puma, Gianluca, E-mail: g.lipuma@lboro.ac.uk [Environmental Nanocatalysis & Photoreaction Engineering, Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)

2017-01-05

Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO{sub 4}{sup −}) and dichromate (Cr{sub 2}O{sub 7}{sup 2−}) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

International Nuclear Information System (INIS)

Wang, Qiang; Huang, Liping; Pan, Yuzhen; Quan, Xie; Li Puma, Gianluca

2017-01-01

Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO_4"−) and dichromate (Cr_2O_7"2"−) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

International Nuclear Information System (INIS)

Stuchbery, A.E.; Doran, C.E.; Byrne, A.P.; Bolotin, H.H.; Dracoulis, G.D.

1986-12-01

Transient-field strengths were measured for 52 Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2 + state of 52 Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

Low-temperature electron properties of Heusler alloys Fe2VAl and Fe2CrAl: Effect of annealing

International Nuclear Information System (INIS)

Podgornykh, S. M.; Svyazhin, A. D.; Shreder, E. I.; Marchenkov, V. V.; Dyakina, V. P.

2007-01-01

We present the results of measurements of low-temperature heat capacity, as well as electrical and magnetic properties of Heusler alloys Fe 2 VAl and Fe 2 CrAl prepared in different ways using various heat treatment regimes. The density of states at the Fermi level is estimated. A contribution of ferromagnetic clusters in the low-temperature heat capacity of the Fe 2 VAl alloy is detected. The change in the number and volume of clusters as a result of annealing of an alloy affects the behavior of their low-temperature heat capacity, resistivity, and magnetic properties

Effect of manganese and chromium on microstructure and toughness of Fe-Cr-Mn alloys resulting from solid-solution treatment

International Nuclear Information System (INIS)

Okazaki, Yoshimitsu; Miyahara, Kazuya; Wade, Noboru; Hosoi, Yuzo

1989-01-01

This study is aimed at making clear the effect of Mn and Cr on the microstructure and toughness of an Fe-Cr-Mn alloy which is considered as one of the candidate alloys for reduced activation materials for the first wall application of the fusion reactor. The microstructures of Fe-12% Cr-(5∼30)% Mn(mass%) alloys after solution treatment at 1373 K for 3.6 ks are markedly varied with Mn contents; α'(martensite) + δ(ferrite) in 5% Mn alloy, α' + δ + ε(martensite) + γ(austenite) in the 10% Mn alloy, α' + ε + γ in 15% Mn alloy, ε + γ in the 20% Mn alloy, and ε + γ +δ in the 25% Mn alloy, and γ + δ in the 30% Mn alloy. It is to be noted that the δ phase increases with increasing Mn content when the Fe-12% Cr alloy contains more than 25% Mn, which suggests that Mn plays the role of a ferrite former. In Fe-15% Mn-Cr alloy, the δ phase is not observed in the range of Cr contents up to 12%, whereas it is markedly increased with the addition of 16% Cr. C, N and Ni are very helpful in forming the γ phase in these alloys as generally known in Fe-Cr-Ni alloys. The toughness evaluated by the Charpy impact test at 273 K and room temperature is very low in the 5% Mn alloy which consists of the α' and δ phases. It is, however, significantly improved by a small amount of the γ phase and increases with increase of γ phase stability. (author)

Effects of sodium environment on the mechanical properties of Fe-2 1/4Cr-1Mo steel

International Nuclear Information System (INIS)

Chopra, O.K.

Mechanical property data on isothermally annealed, thermally aged, and sodium-exposed Fe-2 1/4Cr-1Mo steel are analyzed to evaluate the influence of the sodium environment as well as the effects of the microstructural and compositional changes that occur in the steel during long-term exposure to sodium. Correlations are developed to predict the environmental effects on tensile, creep, fatigue, and creep-fatigue properties of Fe-2 1/4Cr-1Mo steel in sodium. The results indicate that at temperatures <823 K (550 deg. C), degradation of mechanical properties is essentially due to thermal aging. Loss of carbon from the steel reduces both the tensile and creep-rupture strength, but has little or no effect on the fatigue properties. The cyclic properties of Fe-2 1/4Cr-1Mo steel in sodium are superior to those in air. The creep-fatigue behaviour in sodium is significantly different from that in an air environment. The creep-fatigue data are analyzed using the interactive damage rate equations to predict the time-dependent fatigue bahaviour of isothermally annealed Fe-2 1/4Cr-1Mo steel in sodium. (author)

Effects of sodium environment on the mechanical properties of Fe-2 1/4Cr-1Mo steel

International Nuclear Information System (INIS)

Chopra, O.K.

1983-09-01

Mechanical property data on isothermally annealed, thermally aged, and sodium-exposed Fe-2 1/4Cr-1Mo steel are analyzed to evaluate the influence of the sodium environment as well as the effects of the microstructural and compositional changes that occur in the steel during long-term exposure to sodium. Correlations are developed to predict the environmental effects on tensile, creep, fatigue, and creep-fatigue properties of Fe-2 1/4Cr-1Mo steel in sodium. The results indicate that at temperatures 0 C), degradation of mechanical properties is essentially due to thermal aging. Loss of carbon from the steel reduces both the tensile and creep-rupture strength, but has little or no effect on the fatigue properties. The cyclic properties of Fe-2 1/4Cr-1Mo steel in sodium are superior to those in air. The creep-fatigue behavior in sodium is significantly different from that in an air environment. The creep-fatigue data are analyzed using the interactive damage rate equations to predict the time-dependent fatigue behavior of isothermally annealed Fe-2 1/4Cr-1Mo steel in sodium. 15 references, 7 figures, 1 table

Effects of compositional modifications on the sensitization behavior of Fe-Cr-Mn steels

International Nuclear Information System (INIS)

Edgemon, G.L.; Tortorelli, P.F.; Bell, G.E.C.

1992-01-01

Fe-Cr-Mn steels may possibly be used in conjuction with aqueous blankets or coolants in a fusion device. Therefore, standard chemical immersion (modified Strauss) tests were conducted to characterize the effects of compositional modifications on the thermal sensitization behavior of these steels. A good correlation among weight losses, intergranular corrosion, and cracking was found. The most effective means of decreasing their susceptibility was through reduction of the carbon concentration of these steels to 0.1%, but the sensitization resistance of Fe-Cr-Mn-0.1 C compositions was still inferior to type 304L and other similar stainless steels. Alloying additions that form stable carbides did not have a very significant influence on the sensitization behavior. (orig.)

Cross sections for the reactions 54Fe(n,α)51Cr, 54Fe(n,p)54Mn, and 56Fe(n,p)56Mn

International Nuclear Information System (INIS)

Paulsen, A.; Widera, R.; Arnotte, F.; Liskien, H.

1979-01-01

Ratios of cross sections for the reactions 54 Fe(n,α) 51 Cr, 54 Fe(n,p) 54 Mn, and 56 Fe(n,p) 56 Mn were measured by the activation technique. In the 6- to 10-MeV energy range, quasi-monoenergetic neutrons produced by the D(d,n) source reaction were used, while additional data were obtained between 12 and 17 MeV by use of the T(d,n) source reaction. The cross-section ratios have accuracies between 1.5 and 4.5%. 1 figure, 3 tables

Magnetic interactions in HoCr{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.2) investigated by neutron powder diffraction

Energy Technology Data Exchange (ETDEWEB)

Liu, Xinzhi, E-mail: liuxinzhi1984.cn@163.com [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Hao, Lijie; Ma, Xiaobai [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Wang, Chin-Wei [Neutron Group, National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China); Klose, Frank [Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Liu, Yuntao, E-mail: ytliu@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Sun, Kai; Li, Yuqing [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China)

2017-07-01

Highlights: • The temperature dependent magnetism of HoCr{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.2) were investigated by neutron diffraction. • Cr{sup 3+} moment follows a mean field theory while Ho{sup 3+} follows a spin 1/2 model. • An magneto-elastic strain was observed accompanying with the ordering of Cr{sup 3+}. - Abstract: The temperature dependent magnetism of Fe-doped rare earth orthochromite HoCr{sub 1-x}Fe{sub x}O{sub 3}(x = 0, 0.2) was investigated by neutron powder diffraction. It is found that the magnetism of Cr(Fe){sup 3+} can be well understood within mean field theory, while the ordering of Ho{sup 3+} was induced by the Cr(Fe){sup 3+} sublattice and can be satisfyingly described by an effective S = 1/2 model. The absences of both the most common G{sub x}F{sub z} configuration of Cr{sup 3+} and the ordering of Ho{sup 3+} caused by Ho-Ho interaction evidence a strong Ho{sup 3+}-Cr{sup 3+} interaction which dominates this system. On the other hand, a remarkable magnetoelastic strain was observed accompanying the Cr(Fe){sup 3+} ordering. An analysis based on the equation of state with a Grüneisen approximation was performed and revealed magnetic origin of this strain.

MD simulation of atomic displacement cascades in Fe-10 at.%Cr binary alloy

International Nuclear Information System (INIS)

Tikhonchev, M.; Svetukhin, V.; Kadochkin, A.; Gaganidze, E.

2009-01-01

Molecular dynamics simulation of atomic displacement cascades up to 20 keV has been performed in Fe-10 at.%Cr binary alloy at a temperature of 600 K. The N-body interatomic potentials of Finnis-Sinclair type were used. According to the obtained results the dependence of 'surviving' defects amount is well approximated by power function that coincides with other researchers' results. Obtained cascade efficiency for damage energy in the range from 10 to 20 keV is ∼0.2 NRT that is slightly higher than for pure α-Fe. In post-cascade area Cr fraction in interstitials is in range 2-5% that is essentially lower than Cr content in the base alloy. The results on size and amount of vacancy and interstitial clusters generated in displacement cascades are obtained. For energies of 2 keV and higher the defect cluster average size increases and it is well approximated by a linear dependence on cascade energy both for interstitials and vacancies.

MD simulation of atomic displacement cascades in Fe-10 at.%Cr binary alloy

Energy Technology Data Exchange (ETDEWEB)

Tikhonchev, M., E-mail: tikhonchev@sv.ulsu.r [Ulyanovsk State University, Leo Tolstoy Str., 42, Ulyanovsk 432970 (Russian Federation); Joint Stock Company, ' State Scientific Center Research Institute of Atomic Reactors' , 433510 Dimitrovgrad-10 (Russian Federation); Svetukhin, V.; Kadochkin, A. [Ulyanovsk State University, Leo Tolstoy Str., 42, Ulyanovsk 432970 (Russian Federation); Gaganidze, E. [Forschungszentrum Karlsruhe, IMF II, 3640, D-76021 Karlsruhe (Germany)

2009-12-15

Molecular dynamics simulation of atomic displacement cascades up to 20 keV has been performed in Fe-10 at.%Cr binary alloy at a temperature of 600 K. The N-body interatomic potentials of Finnis-Sinclair type were used. According to the obtained results the dependence of 'surviving' defects amount is well approximated by power function that coincides with other researchers' results. Obtained cascade efficiency for damage energy in the range from 10 to 20 keV is approx0.2 NRT that is slightly higher than for pure alpha-Fe. In post-cascade area Cr fraction in interstitials is in range 2-5% that is essentially lower than Cr content in the base alloy. The results on size and amount of vacancy and interstitial clusters generated in displacement cascades are obtained. For energies of 2 keV and higher the defect cluster average size increases and it is well approximated by a linear dependence on cascade energy both for interstitials and vacancies.

Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

International Nuclear Information System (INIS)

Andoh, A.

1997-01-01

The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

A stochastic analysis of the effect of hydrostatic pressure on the pit corrosion of Fe-20Cr alloy

International Nuclear Information System (INIS)

Zhang Tao; Yang Yange; Shao Yawei; Meng, Guozhe; Wang, Fuhui

2009-01-01

The effect of hydrostatic pressure on the pit corrosion behavior of Fe-20Cr alloy was investigated in 3.5% NaCl solution by means of potentiodynamic polarization and potentiostatic technology, and the experiment data was analyzed based on stochastic theory. With the increase of hydrostatic pressure, the pit corrosion resistance of Fe-20Cr alloy was deteriorated, which was distinguished by the decrease of critical pit potential (E cirt ) and the increase of passive current density. The results also demonstrated that there exist two effects of hydrostatic pressure on the corrosion behavior of Fe-20Cr alloy: (1) the pit generation rate was evidently increased compared to that under lower hydrostatic pressure, and the metastable pits become faster and larger. However, it seemed that pit generation mechanism shows no hydrostatic pressure dependence; (2) the probability of pit growth increased with the increase of hydrostatic pressure, which implied that the metastable pit on Fe-20Cr alloy exhibited higher probability to become larger pit cavity during shorter time interval than that under lower hydrostatic pressure.

Phase transformation in rapidly quenched Fe-Cr-Co-Mo-Ti-Si-B alloys

Science.gov (United States)

Zhukov, D. G.; Shubakov, V. S.; Zhukova, E. Kh; Gorshenkov, M. V.

2018-03-01

The research results of phase transformations in Fe-24Cr-16Co-3Mo-0.2Ti-1Si-B alloys (with a boron content of 1 to 3% by mass) obtained by rapid quenching are presented. The structure formation regularities during the melt spinning and during the subsequent crystallization annealing in rapidly quenched bands of the Fe-Cr-Co-Mo-Ti-Si-B system alloys were studied. The changes in the phase composition of the rapidly quenched Fe-Cr-Co-Mo-Ti- Si-B system alloys after quenching at various quench rates and at different boron concentrations in the alloys are studied. It is shown that during crystallization from an amorphous state, at temperatures above 570 °C, in addition to the α-phase, the σ-phase appears first, followed by the γ-phase. Heat treatment of rapidly quenched bands to high-coercive state was carried out. A qualitative assessment of magnetic properties in a high-coercivity state was carried out. An evaluation of the level of magnetic properties in a high-coercivity state allows us to conclude that the application of a magnetic field during crystallization from an amorphous state leads to anisotropy of the magnetic properties, that is, an anisotropic effect of thermo-magnetic treatment is detected.

Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

International Nuclear Information System (INIS)

Qiu, X.W.; Zhang, Y.P.; Liu, C.G.

2014-01-01

Highlights: • Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. • Al 2 CrFeNiCoCuTi x coatings show excellent corrosion resistance and wear resistance. • Al 2 CrFeNiCoCuTi x coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials

Neutron powder diffraction investigation of magnetic structure and spin reorientation transition of HoFe{sub 1-x}Cr{sub x}O{sub 3} solid solutions

Energy Technology Data Exchange (ETDEWEB)

Liu, Xinzhi [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Hao, Lijie, E-mail: haolijie@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Liu, Yuntao; Ma, Xiaobai; Meng, Siqin; Li, Yuqing; Gao, Jianbo; Guo, Hao; Han, Wenze; Sun, Kai; Wu, Meimei [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China); Chen, Xiping; Xie, Lei [Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Klose, Frank [Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [Department of Nuclear Physics, China Institute of Atomic Energy, Beijing 102413 (China)

2016-11-01

Orthoferrite solid solution HoFe{sub 1−x}Cr{sub x}O{sub 3} (x=0, 0.2,…,1.0) was synthesized via solid state reaction methods. The crystal structure, magnetism and spin reorientation properties of this system were investigated by X-ray diffraction, neutron powder diffraction and magnetic measurements. For compositions of x≤0.6, the system exhibits similar magnetic properties to HoFeO{sub 3}. With increasing Cr-doping, the system adopts a Γ{sub 4}(G{sub x}A{sub y}F{sub z}) magnetic configuration with a decreased Neel temperature from 640 K to 360 K. A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was also observed in this system with an increase in transition temperature from 56 K to about 200 K due to competition between the Fe(Cr)–Fe(Cr) and Ho–Fe(Cr) interactions. For the x≥0.8, the system behaves more like HoCrO{sub 3} which adopts a Γ{sub 2}(F{sub x}C{sub y}G{sub z}) configuration with no spin reorientation below the Neel temperature T{sub N}. Throughout the whole substitution range, we found that the saturated moment of Fe(Cr) was less than the ideal value for a free ion, which implies the existence of spin fluctuation in this system. A systematic magnetic structure variation with Cr-substitution is revealed by Rietveld refinement. A phase diagram combining the results of the magnetic measurements and neutron powder diffraction results was obtained. - Highlights: • With Cr-substitution in the HoFe{sub 1−x}Cr{sub x}O{sub 3} system, A Γ{sub 42} spin reorientation of Fe(Cr){sup 3+} was observed with an increase in transition temperature from 56 K to about 200 K for x=0−0.6. • The saturated moment of Fe(Cr) position was found to be systematically less than the ideal value of free ion, and thus implies the presence of spin quantum fluctuation. • A composition–temperature phase diagram throughout x=0–1 for HoFe{sub 1−x}Cr{sub x}O{sub 3} system was established.

The electronic, magnetic and optical properties of ZnO doped with doubles impurities (Cr, Fe): An LDA-SIC and Monte Carlo study

Energy Technology Data Exchange (ETDEWEB)

Salmani, El Mehdi, E-mail: elmehdisalmani@gmail.com [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Laghrissi, Ayoub; Lamouri, Rachida; Ez-Zahraouy, Hamid [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Benyoussef, Abdelilah [Institute for Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Académie Hassan II des Sciences et Techniques, Rabat (Morocco)

2017-01-15

Electronic structure, magnetic and optical properties of ZnO doped with single and double impurities Zn{sub 1−x}Cr{sub x}O, Zn{sub 1−x}Fe{sub x}O, and Zn{sub 1−2x}Cr{sub x}Fe{sub x}O (x=0.03 and 0.06) are investigated using first-principles calculations. Based on the Korringa–Kohn–Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of doubles impurities (Cr, Fe) doped ZnO. To support our results, we apply the self-interaction-corrected local density approximation (SIC-LDA) to study the electronic structure, optical and magnetic properties of Co-doped ZnO with doubles impurities (Cr, Fe) showing that the half-metallic ferromagnetic state still persists. The stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with high Neel temperature. - Highlights: • The electronic structure calculations for ZnO doped with doubles impurities (Cr, Fe) have been discussed. • The half-metallic aspect was proven to take place for doubles impurities (Cr, Fe) codoped ZnO. • The doubles impurities (Cr, Fe)impurities are shown to introduce the necessary magnetic moment that makes ZnO good candidates for spintronic applications.

Tuning Fermi level of Cr{sub 2}CoZ (Z=Al and Si) inverse Heusler alloys via Fe-doping for maximum spin polarization

Energy Technology Data Exchange (ETDEWEB)

Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Saini, Hardev S. [Department of Physics, Panjab University, Chandigarh-160014 (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Reshak, Ali H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India)

2014-12-15

We report full potential treatment of electronic and magnetic properties of Cr{sub 2−x}Fe{sub x}CoZ (Z=Al, Si) Heusler alloys where x=0.0, 0.25, 0.5, 0.75 and 1.0, based on density functional theory (DFT). Both parent alloys (Cr{sub 2}CoAl and Cr{sub 2}CoSi) are not half-metallic frromagnets. The gradual replacement of one Cr sublattice with Fe induces the half-metallicity in these systems, resulting maximum spin polarization. The half-metallicity starts to appear in Cr{sub 2−x}Fe{sub x}CoAl and Cr{sub 2−x}Fe{sub x}CoSi with x=0.50 and x=0.25, respectively, and the values of minority-spin gap and half-metallic gap or spin-flip gap increase with further increase of x. These gaps are found to be maximum for x=1.0 for both cases. An excellent agreement between the structural properties of CoFeCrAl with available experimental study is obtained. The Fermi level tuning by Fe-doping makes these alloys highly spin polarized and thus these can be used as promising candidates for spin valves and magnetic tunnelling junction applications. - Highlights: • Tuning of E{sub F} in Cr{sub 2}CoZ (Z=Al, Si) has been demonstrated via Fe doping. • Effect of Fe doping on half-metallicity and magnetism have been discussed. • The new alloys have a potential of being used as spin polarized electrodes.

Kinetic Monte Carlo simulation of phase-precipitation versus instability behavior in short period FeCr superlattices

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Martínez, F.J. [UCAM, Universidad Católica de Murcia, Campus de los Jerónimos, 30107 Guadalupe (Murcia) (Spain); Castejón-Mochón, J.F., E-mail: jfcastejon@ucam.edu [UCAM, Universidad Católica de Murcia, Campus de los Jerónimos, 30107 Guadalupe (Murcia) (Spain); Castrillo, P.; Berenguer-Vidal, R. [UCAM, Universidad Católica de Murcia, Campus de los Jerónimos, 30107 Guadalupe (Murcia) (Spain); Dopico, I.; Martin-Bragado, I. [IMDEA Materials Institute, Eric Kandel 2, 28906 Getafe (Madrid) (Spain)

2017-02-15

The structural evolution of FeCr superlattices has been studied using a quasi-atomistic Object Kinetic Monte Carlo model. Superlattices with different spatial periods have been simulated for anneal durations from few hours to several months at 500 °C. Relatively-long period superlattices stabilize into Fe-rich and Cr-rich layers with compositions close to those of bulk α and α′ phases. In contrast, superlattices with very short periods (4, 5, 6 nm) are observed to undergo instability and, for long annealing times, evolve into three-dimensionally decomposed regions, in qualitative agreement to recent experimental observations. The instability onset is delayed as the spatial period increases, and it occurs via interface roughness. This evolution can be explained as a minimization of the free-energy associated to the α/α′ interfaces. A comprehensive description of the evolution dynamics of FeCr-based structures is obtained with our model.

Structural and magnetic characterization of Fe2CrSi Heusler alloy nanoparticles as spin injectors and spin based sensors

Science.gov (United States)

Saravanan, G.; Asvini, V.; Kalaiezhily, R. K.; Parveen, I. Mubeena; Ravichandran, K.

2018-05-01

Half-metallic ferromagnetic [HMF] nanoparticles are of considerable interest in spintronics applications due to their potential use as a highly spin polarized current source. HMF exhibits a semiconductor in one spin band at the Fermi level Ef and at the other spin band they poses strong metallic nature which shows 100 % spin polarization at Ef. Fe based full Heusler alloys are primary interest due to high Curie temperature. Fe2CrSi Heusler alloys are synthesized using metallic powders of Fe, Cr and Si by mechanical alloying method. X-Ray diffractions studies were performed to analyze the structural details of Fe2CrSi nanoparticles with High resolution scanning electron microscope (HRSEM) studies for the morphological details of nanoparticles and magnetic properties were studied using Vibrating sample magnetometer (VSM). XRD Data analysis conforms the Heusler alloy phase showing the existence of L21 structure. Magnetic properties are measured for synthesized samples exhibiting a soft magnetic property possessing low coercivity (HC = 60.5 Oe) and saturation magnetic moment of Fe2CrSi is 3.16 µB, which is significantly higher than the ideal value of 2 µB from the Slater-Pauling rule due to room temperature measurement. The change in magnetic properties are half-metallic nature of Fe2CrSi is due to the shift of the Fermi level with respect to the gap were can be used as spin sensors and spin injectors in magnetic random access memories and other spin dependent devices.

Synthesis, crystallization behavior and surface modification of Ni-Cr-Si-Fe amorphous alloy

International Nuclear Information System (INIS)

Iqbal, M.; Akhter, J.I.; Rajput, M.U.; Mahmood, K.; Hussain, Z.; Hussain, S.; Rafiq, M.

2011-01-01

A quaternary Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ amorphous alloy was synthesized by melt spinning technique. Surface modification was done by electron beam melting (EBM), neutron irradiation and gamma-rays. Microstructure of as cast, annealed and modified samples was examined by scanning electron microscope. Crystallization behavior was studied by annealing the samples in vacuum at different temperatures in the range 773-1073 K. Techniques of X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for characterization. Differential scanning calorimetry (DSC) was conducted at various heating rates in the range 10-40 K/min. Thermal parameters like glass transition temperature T/sub g/, crystallization temperature T/sub x/, supercooled liquid region delta T/sub x/ and reduced glass transition temperature T/sub rg/ were measured. The Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ alloy exhibits wide supercooled liquid region of 60 K indicating good thermal stability. The activation energy was calculated to be 160 +- 4 kJ/mol using Kissinger and Ozawa equations respectively which indicates high resistance against crystallization. The XRD results of the samples annealed at 773 K, 923 K, 973 K and 1073 K/20 min show nucleation of Ni/sub 2/Cr/sub 3/ and NiCrFe crystalline phases. Vickers microhardness of the as cast ribbon was measured to be 680. About 30-50 % increase in hardness was achieved by applying EBM technique. (author)

Neutron cross section covariances in the resonance region: 52Cr, 56Fe, 58Ni

Energy Technology Data Exchange (ETDEWEB)

Oblozinsky, P.; Cho, Y.-S.; Mattoon, C.M.; Mughabghab, S.F.

2010-08-03

We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.

Development and quality assessments of commercial heat production of ATF FeCrAl tubes

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-01

Development and quality assessment of the 2^nd generation ATF FeCrAl tube production with commercial manufacturers were conducted. The manufacturing partners include Sophisticated Alloys, Inc. (SAI), Butler, PA for FeCrAl alloy casting via vacuum induction melting, Oak Ridge National Laboratory (ORNL) for extrusion process to prepare the master bars/tubes to be tube-drawn, and Rhenium Alloys, Inc. (RAI), North Ridgeville, OH, for tube-drawing process. The masters bars have also been provided to Los Alamos National Laboratory (LANL) who works with Century Tubes, Inc., (CTI), San Diego, CA, as parallel tube production effort under the current program.

Size-dependent magnetic and structural properties of CoCrFeO4 nano-powder prepared by solution self-combustion

Science.gov (United States)

Sijo, A. K.; Dutta, Dimple P.

2018-04-01

The study reports the tuning of magnetic and structural properties of nano-sized CoCrFeO4 via post-annealing treatment. CoCrFeO4 nano-powder has been prepared by solution self-combustion method. The structural and magnetic properties have been studied over a range of annealing temperatures (300-900 °C). The formation of the phase pure CoCrFeO4 spinel has been confirmed from powder XRD analysis. The crystallite size is observed to increase with an increase in annealing temperature. On annealing, the value of magnetic parameters-remanence, coercivity and saturation magnetization have enhanced. All the samples exhibit irreversibility at low-temperature measurements.

Interface Resistance between FeCr Interconnects and La0.85Sr0.15Mn1.1O3

DEFF Research Database (Denmark)

Mikkelsen, Lars; Neufeld, Kai; Hendriksen, Peter Vang

2009-01-01

The long term oxidation behaviour and the electrical interface resistance between FeCr interconnects and La0,85Sr0,15Mn1,1O3 plates was studied by a DC four-point method in air at 750{degree sign}C for 10000 h. The tested FeCr alloys were: Crofer 22 APU, Sanergy HT, Plansee IT10, Plansee IT11, an....... Low degradation rates of less than 1 mcm2/1000 h were measured on all interfaces. The microstructure analysis showed that a duplex Cr2O3-(Mn,Co,Cr)3O4 oxide scale with a thickness of 3-5 µm had evolved on the alloys....

Sulfur solubility of liquid and solid Fe-Cr alloys. A thermodynamic analysis

Energy Technology Data Exchange (ETDEWEB)

Waldner, Peter [Leoben Univ. (Austria). Dept. of General, Analytical and Physical Chemistry

2015-04-15

Gibbs energy modeling for sulfur solving liquid and solid iron-chromium phases with body- and face-centered cubic structure has been carried out using a substitutional approach. Experimental data available from the literature on sulfur potentials in the temperature range 1 525 to 1 755 C for the liquid metallic phase and 1 000 to 1 300 C for the solid alloys have been taken into consideration. Recent thermodynamic evaluations of the Fe-S and Cr-S binary subsystems served as basis for the presented work. The obtained models allow a satisfactory reproduction of the majority of the sulfur potential data as well as the prediction of an isothermal partial section at 1 300 C. Consistent embedding of the optimized Gibbs energies within a recent thermodynamic modeling of the complete Cr-Fe-S system is achieved.

Effect of Nb and Cr incorporation on the structural and magnetic properties of rapidly quenched FeCoSiB microwires

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Partha; Roy, R.K.; Mitra, A. [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Panda, A.K., E-mail: akpanda@nmlindia.org [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Churyukanova, Margarita; Kaloshkin, Sergey [National University of Science and Technology, MISIS, Leninsky Prospect, 4, Moscow 119049 (Russian Federation)

2012-08-15

Rapidly quenched microwires with a nominal composition of Fe{sub 39}Co{sub 39}Si{sub 8}B{sub 14} (A{sub O}), Fe{sub 37}Co{sub 37}Nb{sub 4}Si{sub 8}B{sub 14} (A{sub N}) and Fe{sub 36}Co{sub 36}Nb{sub 4}Cr{sub 2}Si{sub 8}B{sub 14} (A{sub NC}) have been investigated. Devitrification of as-quenched microwires showed that crystallization temperatures increased with simultaneous incorporation of Nb and Cr as in A{sub NC} alloy. Addition of these elements also contributed to an increase in activation energy in A{sub N} and A{sub NC} alloys. Nb addition reduced the particle size, which became much finer in the case of the Cr-containing alloy. Although Nb addition did not have much effect on lowering the Curie temperature T{sub C} of the amorphous phase, Cr substitution lowered T{sub C} to 698 K from high values of 785 K and 787 K observed in the no. A{sub O} and A{sub NC} alloys, respectively. However, the Cr addition revealed a better Giant magneto-impedance (GMI) response compared to the other alloys. Such improved GMI properties in the Cr-containing alloy are attributed to lower values of the coercivity and magnetostriction in the alloy containing both Nb and Cr. - Highlights: Black-Right-Pointing-Pointer FeCoSiB based rapidly quenched microwires prepared by in-rotating-water quenching system. Black-Right-Pointing-Pointer Effect of Nb and Cr on the thermal and GMI behavior of FeCoSiB microwires has been investigated. Black-Right-Pointing-Pointer Effect of Nb and Cr on magnetic properties has also been investigated.

Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer

Directory of Open Access Journals (Sweden)

Chun Dong

2011-01-01

Full Text Available Abstract A thin FePt film was deposited onto a CrV seed layer at 400°C and showed a high coercivity (~3,400 Oe and high magnetization (900–1,000 emu/cm3 characteristic of L10 phase. However, the magnetic properties of patterned media fabricated from the film stack were degraded due to the Ar-ion bombardment. We employed a deposition-last process, in which FePt film deposited at room temperature underwent lift-off and post-annealing processes, to avoid the exposure of FePt to Ar plasma. A patterned medium with 100-nm nano-columns showed an out-of-plane coercivity fivefold larger than its in-plane counterpart and a remanent magnetization comparable to saturation magnetization in the out-of-plane direction, indicating a high perpendicular anisotropy. These results demonstrate the high perpendicular anisotropy in FePt patterned media using a Cr-based compound seed layer for the first time and suggest that ultra-high-density magnetic recording media can be achieved using this optimized top-down approach.

Study of the conduction phenomenon in the system Zn(1-x)FeCrO4Nix

International Nuclear Information System (INIS)

Zhou Yuan; Xia Yuanfu; Zhang Shiyuan; Chen Kunji

1993-01-01

In order to explore an 'anomalous' conduction phenomenon in the system Zn (1-x) FeCrO 4 Ni x which was investigated with Moessbauer spectra, X-rays diffraction, infrared spectra and other methods. The results show that the conductivity anomaly is not an intrinsic behavior but arises from the moisture-adsorption. Their native conduction is similar to that of semiconductors, obeying the relationship σ = σ ∝ exp (E a /KT). All samples crystallize in cubic symmetry and their lattice parameters increase with x. The cation distribution is (Zn (1-x) Fe x ) [Fe ( -1 -x) Ni x Cr]O 4 . No phase change occurs in the temperature range from 283 to 423 K

Column study of enhanced Cr(VI) removal and longevity by coupled abiotic and biotic processes using Fe0 and mixed anaerobic culture.

Science.gov (United States)

Zhong, Jiawei; Yin, Weizhao; Li, Yongtao; Li, Ping; Wu, Jinhua; Jiang, Gangbiao; Gu, Jingjing; Liang, Hao

2017-10-01

In this study, Fe 0 and mixed anaerobic culture were integrated in one column to investigate the coupled abiotic and biotic effects on hexa-valent chromium (Cr(VI)) removal and column longevity with an abiotic Fe 0 column in the control experiments. According to the breakthrough study, a slower Cr(VI) breakthrough rate of 0.19 cm/PV was observed in the biotic Fe 0 column whereas the value in the abiotic Fe 0 column was 0.30 cm/PV, resulting in 64% longer life-span and 62% higher Cr(VI) removal capacity in the biotic Fe 0 column than the abiotic one. The solid phase characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) confirmed that this enhancement was attributed to the higher consumption of iron and greater production of diverse reactive minerals (e.g., green rust, magnetite and lepidocrocite) induced by the synergistic interaction of Fe 0 and anaerobic culture, providing more reactive sites for Cr(VI) adsorption, reduction and co-precipitation. Furthermore, the decreasing breakthrough rates and growing iron corrosion along the biotic Fe 0 column demonstrated an inhomogeneous distribution of reactive zones in the column and its latter 3/5 section was considered to be the most reactive area for Cr(VI) removal. These results indicate that the inoculation of microorganisms in Fe 0 -based permeable reactive barriers will enable this technology a higher removal capacity and longer life-span for the remediation of Cr(VI)-contaminated groundwater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uptake of CrO{sub 4}{sup 2-} ions by Fe-treated tri-calcium phosphate

Energy Technology Data Exchange (ETDEWEB)

Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E., E-mail: juan.serrano@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2010-07-01

CrO{sub 4}{sup 2-} ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10{sup -4} M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO{sub 4}{sup 2-} ions was 7.10 x 10{sup -3} mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters {Delta}H{sup 0}, {Delta}G{sup 0} and {Delta}S{sup 0} were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

Ratio dependence of the visible light photocatalytic efficiency for Zn{sub 2}Ti{sub 0.9}Cr{sub y}Fe{sub [0.1-y]}O{sub 4}: Cr/Fe (0.02 < y < 0.08) photocatalyst synthesized by using a solid state reaction method

Energy Technology Data Exchange (ETDEWEB)

Borse, P. H. [International Advanced Research Center for Powder Metallurgy and New Materials, Hyderabad (India); Cho, C. R. [Pusan National University, Miryang (Korea, Republic of); Lim, K. T. [Pukyong National University, Busan (Korea, Republic of); Lee, Y. J.; Bae, J. S.; Jeong, E. D.; Kim, H. G. [Korea Basic Science Institute, Busan (Korea, Republic of)

2011-07-15

We synthesized four different photocatalyst systems of Zn{sub 2}TiO{sub 4}, Zn{sub 2}Ti{sub 1-x}Fe{sub x}O{sub 4}, Zn{sub 2}Ti{sub 1-x}Cr{sub x}O{sub 4} (0 {<=} x < 0.8) and Zn{sub 2}Ti{sub 0.9}Cr{sub y}Fe{sub [0.1]-y}O{sub 4} (0.02 < y < 0.08) by using a solid state reaction method. For the first time, the UV-active photocatalyst Zn{sub 2}TiO{sub 4} was converted to a visible light active material by controlled doping/co-doping with Cr and Fe metal-ions at Ti substitutional sites, and investigated the structural, optical and photocatalytic water decomposition properties of that materials. The co-doping induces strong absorption bands (at {lambda} {approx} 480 nm and {lambda} {approx} 620 nm) within the Zn{sub 2}TiO{sub 4} band gap. The optimum system of Zn{sub 2}Ti{sub 0.9}Cr{sub 0.05}Fe{sub 0.05}O{sub 4} yielded maximum H{sub 2} generation. In contrast to the visible light inactivity of Fe- and Cr-doped Zn{sub 2}TiO{sub 4}, the H{sub 2} production from co-doped samples under visible light irradiation increased till the optimum 'y' value. Consequently, here exists an optimal co-dopant concentration for efficient photocatalytic hydrogen production under visible light ({lambda} {>=} 420 nm).

Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys

Directory of Open Access Journals (Sweden)

Bae K.C.

2017-06-01

Full Text Available To investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the number of nucleation sites and the volume fraction of the α phase decreased. We observed a significant difference in the shape and size of the α phase in the matrix before and after Fe addition. In addition, these morphological deformations were accompanied by a change in the shape of the α phase, which became increasingly discontinuous, and changed into globular-type α phase in the matrix. These phenomena affected the microstructure and mechanical properties of Ti alloys. Specimen #2 exhibited a high ultimate tensile strength (1071 MPa, which decreased with further addition of Fe.

Structure of Fe-Ni-Cr steel welded joints

International Nuclear Information System (INIS)

Bratukhin, A.G.; Maslenkov, S.B.; Logunov, A.V.

1993-01-01

Properties of a welded joint depend on the structure of metal of the joint and near the joint areas subjected to thermal effect in the process of welding. The well-known phenomena, accompanying the welding (grain growth in near the joint area, intergrain slip, stressed state related to crystallization and rapid cooling), as well as certain other processes, which have been insufficiently studied either due to their poor pronouncement or owing to imperfection of the equipment and methods employed, were analyzed, as applied to stainless hihg-strength Fe-Ni-Cr steels

The Analysis of the General Performance and Mechanical Behavior of Unirradiated FeCrAl Alloys Before and After Welding

Energy Technology Data Exchange (ETDEWEB)

Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-06-03

The present report summarizes and discusses the preliminary results for the in-depth characterization of the modern, nuclear-grade FeCrAl alloys currently under development. The alloys were designed for enhanced radiation tolerance and weldability, and the research is currently being pursued by the Department of Energy (DOE) Nuclear Energy Enabling Technologies (NEET) program. Last year, seven candidate FeCrAl alloys with well-controlled chemistry and microstructures were designed and produced; welding was performed under well-controlled conditions. The structure and general performance of unirradiated alloys were assessed using standardized and advanced microstructural characterization techniques and mechanical testing. The primary objective is to identify the best candidate alloy, or at a minimum to identify the contributing factors that increase the weldability and radiation tolerance of FeCrAl alloys, therefore enabling future generations of FeCrAl alloys to deliver better performance parameters. This report is structured so as to describe these critical assessments of the weldability; radiation tolerance will be reported on in later reports from this program.

Epitaxial Bi2 FeCrO6 Multiferroic Thin Film as a New Visible Light Absorbing Photocathode Material.

Science.gov (United States)

Li, Shun; AlOtaibi, Bandar; Huang, Wei; Mi, Zetian; Serpone, Nick; Nechache, Riad; Rosei, Federico

2015-08-26

Ferroelectric materials have been studied increasingly for solar energy conversion technologies due to the efficient charge separation driven by the polarization induced internal electric field. However, their insufficient conversion efficiency is still a major challenge. Here, a photocathode material of epitaxial double perovskite Bi(2) FeCrO(6) multiferroic thin film is reported with a suitable conduction band position and small bandgap (1.9-2.1 eV), for visible-light-driven reduction of water to hydrogen. Photoelectrochemical measurements show that the highest photocurrent density up to -1.02 mA cm(-2) at a potential of -0.97 V versus reversible hydrogen electrode is obtained in p-type Bi(2) FeCrO(6) thin film photocathode grown on SrTiO(3) substrate under AM 1.5G simulated sunlight. In addition, a twofold enhancement of photocurrent density is obtained after negatively poling the Bi(2) FeCrO(6) thin film, as a result of modulation of the band structure by suitable control of the internal electric field gradient originating from the ferroelectric polarization in the Bi(2) FeCrO(6) films. The findings validate the use of multiferroic Bi(2) FeCrO(6) thin films as photocathode materials, and also prove that the manipulation of internal fields through polarization in ferroelectric materials is a promising strategy for the design of improved photoelectrodes and smart devices for solar energy conversion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical and structural effects of phosphorus on the corrosion behavior of ion beam mixed Fe-Cr-P alloys

International Nuclear Information System (INIS)

Demaree, J.D.; Was, G.S.; Sorensen, N.R.

1992-01-01

An experimental program was conducted to determine the mechanisms by which phosphorus affects the corrosion and passivation behavior of Fe-Cr-P alloys. To identify separately the effects of structure and chemistry on the corrosion behavior, thin films of Fe-10Cr-xP (0≤x≤35 at.%) were prepared by ion beam mixing. Films with a phosphorus content greater than approximately 20at.% were found to be entirely amorphous. Devitrification of the amorphous phase was accomplished by heating the samples to 450degC in an inert environment. Standard polarization tests of the sulfuric acid (with and without Cl - ) indicated that the films containing phosphorus were more corrosion resistant than Fe-10Cr, at both active and passive potentials. There was a monotonic relationship between the amount of phosphorus in the alloy and the corrosion resistance, with the open-circuit corrosion rate of Fe-10Cr-35P nearly four orders of magnitude lower than that of Fe-10Cr. Devitrification of the alloys had no significant effect on the corrosion rate, indicating that the primary effect of phosphorus is chemical in nature, and not structural. The passive oxides were depth-profiled using X-ray photoelectron spectroscopy, which indicated that phosphorus was a primary constituent, as phosphate. The presence of phosphate in the passive oxides reduced the overall corrosion rate directly, by suppressing anodic dissolution. The presence of phosphorus did enhance chromium enrichment in the oxide, but that was not thought to be the primary mechanism by which phosphorus increased the corrosion resistance. (orig.)

Kondo effect and spin-glass freezing of the magnetic impurities Cr, Mn, and Fe in superconducting palladium hydride

International Nuclear Information System (INIS)

van Dongen, J.C.M.; van Dijk, D.; Mydosh, J.A.

1981-01-01

Through low-field ac susceptibility measurements we have determined the depression of the superconducting transition temperature T/sub c/ in palladium hydride (T/sub c/0 = 9.3 K) as a function of impurity concentration x for Cr, Mn, and Fe. For Cr and Fe similar values for the initial T/sub c/ depression were found, i.e., -150 K/at. % Cr and -145 K/at. % Fe. From resistivity experiments we are able to estimate the Kondo temperatures T/sub K/, i.e., T/sub K/approx. =10 K for Cr and T/sub K/approx. =5 K for Fe. Since i.e., T/sub K/approx. =10 K for Cr and T/sub K/approx. =5 K for Fe. Since systems exhibits an enhanced pair breaking as described by the theory of Mueller-Hartmann and Zittartz. In contrast, for Mn the initial T/sub c/ depression is -21 K/at. % and T/sub K/<< T/sub c/0, as can be concluded from our resistivity measurements. This means that Mn in PdH exhibits a temperature-independent pair breaking of the Abrikosov and Gor'kov type. However, at larger Mnx values a shoulder appears in T/sub c/(x). We interpret this enhanced superconductivity, according to the theory of Soukoulis and Grest, as being due to the onset of time correlations and short-range antiferromagnetic ordering between the Mn moments. These interaction effects are a precursor to the spin-glass freezing at a lower temperature T/sub f/. Our results suggest a favorable coexistance of superconductivity with the spin-glass state

Stability of nanoscale secondary phases in an oxide dispersion strengthened Fe-12Cr alloy

International Nuclear Information System (INIS)

Castro, V. de; Marquis, E.A.; Lozano-Perez, S.; Pareja, R.; Jenkins, M.L.

2011-01-01

Transmission electron microscopy and atom-probe tomography were used to characterize on a near-atomic scale the microstructure and oxide and carbide phases that form during thermo-mechanical treatments of a model oxide dispersion strengthened Fe-12 wt.% Cr-0.4 wt.% Y 2 O 3 alloy. It was found that some of the Y-rich nanoparticles retained their initial crystallographic structure but developed a Cr-enriched shell, while others evolved into ternary oxide phases during the initial processing. The Y- and Cr-rich oxide phases formed remained stable after annealing at 1023 K for 96 h. However, the number of Cr-rich carbides appeared to increase, inducing Cr depletion in the matrix.

Stability of nanoscale secondary phases in an oxide dispersion strengthened Fe-12Cr alloy

Energy Technology Data Exchange (ETDEWEB)

Castro, V. de, E-mail: vanessa.decastro@uc3m.es [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Marquis, E.A.; Lozano-Perez, S. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain); Jenkins, M.L. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)

2011-06-15

Transmission electron microscopy and atom-probe tomography were used to characterize on a near-atomic scale the microstructure and oxide and carbide phases that form during thermo-mechanical treatments of a model oxide dispersion strengthened Fe-12 wt.% Cr-0.4 wt.% Y{sub 2}O{sub 3} alloy. It was found that some of the Y-rich nanoparticles retained their initial crystallographic structure but developed a Cr-enriched shell, while others evolved into ternary oxide phases during the initial processing. The Y- and Cr-rich oxide phases formed remained stable after annealing at 1023 K for 96 h. However, the number of Cr-rich carbides appeared to increase, inducing Cr depletion in the matrix.

Unraveling the magnetic properties of BiFe{sub 0.5}Cr{sub 0.5}O{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Vinai, G.; Petrov, A. Yu.; Panaccione, G.; Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy); Khare, A. [CNR-SPIN Napoli and Dipartimento di Fisica, Università di Napoli “Federico II,” I-80126 Napoli (Italy); Department of Physics, Sungkyunkwan University, Suwon 440 746 (Korea, Republic of); Rana, D. S. [Department of Physics, Indian Institute of Science Education and Research Bhopal, Govindpura, Bhopal 462023 (India); Di Gennaro, E.; Scotti di Uccio, U.; Miletto Granozio, F. [CNR-SPIN Napoli and Dipartimento di Fisica, Università di Napoli “Federico II,” I-80126 Napoli (Italy); Gobaut, B. [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, Area Science Park, 34149 Trieste (Italy); Moroni, R. [CNR-SPIN, Corso Perrone 24, I-16152 Genova (Italy); Rossi, G. [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy); Department of Physics, Università degli Studi di Milano, via Celoria 16, I-20133 Milano (Italy)

2015-11-01

We investigate the structural, chemical, and magnetic properties on BiFe{sub 0.5}Cr{sub 0.5}O{sub 3} (BFCO) thin films grown on (001) (110) and (111) oriented SrTiO{sub 3} (STO) substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

Changes in cluster magnetism and suppression of local superconductivity in amorphous FeCrB alloy irradiated by Ar"+ ions

International Nuclear Information System (INIS)

Okunev, V.D.; Samoilenko, Z.A.; Szymczak, H.; Szewczyk, A.; Szymczak, R.; Lewandowski, S.J.; Aleshkevych, P.; Malinowski, A.; Gierłowski, P.; Więckowski, J.; Wolny-Marszałek, M.; Jeżabek, M.; Varyukhin, V.N.; Antoshina, I.A.

2016-01-01

We show that cluster magnetism in ferromagnetic amorphous Fe_6_7Cr_1_8B_1_5 alloy is related to the presence of large, D=150–250 Å, α-(Fe Cr) clusters responsible for basic changes in cluster magnetism, small, D=30–100 Å, α-(Fe, Cr) and Fe_3B clusters and subcluster atomic α-(Fe, Cr, B) groupings, D=10–20 Å, in disordered intercluster medium. For initial sample and irradiated one (Φ=1.5×10"1"8 ions/cm"2) superconductivity exists in the cluster shells of metallic α-(Fe, Cr) phase where ferromagnetism of iron is counterbalanced by antiferromagnetism of chromium. At Φ=3×10"1"8 ions/cm"2, the internal stresses intensify and the process of iron and chromium phase separation, favorable for mesoscopic superconductivity, changes for inverse one promoting more homogeneous distribution of iron and chromium in the clusters as well as gigantic (twice as much) increase in density of the samples. As a result, in the cluster shells ferromagnetism is restored leading to the increase in magnetization of the sample and suppression of local superconductivity. For initial samples, the temperature dependence of resistivity ρ(T)~T"2 is determined by the electron scattering on quantum defects. In strongly inhomogeneous samples, after irradiation by fluence Φ=1.5×10"1"8 ions/cm"2, the transition to a dependence ρ(T)~T"1"/"2 is caused by the effects of weak localization. In more homogeneous samples, at Φ=3×10"1"8 ions/cm"2, a return to the dependence ρ(T)~T"2 is observed. - Highlights: • The samples at high dose of ion irradiation become more homogeneous. • Gigantic increase in density of the samples (twice as much) is observed. • Ferromagnetism in large Fe–Cr clusters is restored. • Ferromagnetism of Fe–Cr clusters suppresses local superconductivity in them. • The participation of quantum defects in scattering of electrons is returned.

Chromium Extraction via Chemical Processing of Fe-Cr Alloys Fine Powder with High Carbon Content

Science.gov (United States)

Torres, D. M.; Navarro, R. C. S.; Souza, R. F. M.; Brocchi, E. A.

2017-06-01

Ferrous alloys are important raw materials for special steel production. In this context, alloys from the Fe-Cr system, with typical Cr weight fraction ranging from 0.45 to 0.95, are prominent, particularly for the stainless steel industry. During the process in which these alloys are obtained, there is considerable production of fine powder, which could be reused after suitable chemical treatment, for example, through coupling pyrometallurgical and hydrometallurgical processes. In the present study, the extraction of chromium from fine powder generated during the production of a Fe-Cr alloy with high C content was investigated. Roasting reactions were performed at 1073 K, 1173 K, and 1273 K (800 °C, 900 °C, and 1000 °C) with 300 pct (w/w) excess NaOH in an oxidizing atmosphere (air), followed by solubilization in deionized water, selective precipitation, and subsequent calcination at 1173 K (900 °C) in order to convert the obtained chromium hydroxide to Cr2O3. The maximum achieved Cr recovery was around 86 pct, suggesting that the proposed chemical route was satisfactory regarding the extraction of the chromium initially present. Moreover, after X-ray diffraction analysis, the final produced oxide has proven to be pure Cr2O3 with a mean crystallite size of 200 nm.

Assessment of the concentration of Cr, Mn and Fe in sediment using ...

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determination of levels of Cr, Mn and Fe in sediment samples and the results have ... produced within the plasma emit radiation over a broad spectral range, from UV ... intake [36] and their oxides play important role in the soil for fixing trace ...

Effect of cooling rate on the microstructure and properties of FeCrVC

International Nuclear Information System (INIS)

Bleckmann, M.; Gleinig, J.; Hufenbach, J.; Wendrock, H.; Giebeler, L.; Zeisig, J.; Diekmann, U.; Eckert, J.; Kühn, U.

2015-01-01

Highlights: • Effect of cooling rate on microstructure and microhardness of newly developed steel. • Intensive study of DSC measurements was done including different cooling rates. • Examinations by XRD, EDS and EBSD as well as microhardness on the DSC samples. • Matrix phase changes with cooling rates from ferrit to martensite. • Thermodynamic calculations of solidification process shows good agreement. - Abstract: In this work a systematic investigation of the influence of the cooling rate on the microstructure and properties of a newly developed Fe92.7Cr4.2V2.1C1 (FeCrVC) tool steel is presented. By applying a tailored casting process and sufficiently high cooling rates excellent mechanical properties are obtained for the presented alloy already in the as-cast state. Since no subsequent heat treatment is required, the cooling parameters applied during the casting process play a key role with respect to the evolving microstructure and resulting properties. In the present publication the effect of the cooling rate on the microstructure and properties of as-solidified FeCrVC was investigated. By using differential scanning calorimetry (DSC), several samples were heated up and cooled with continuous rates of 3–50 K/min. The received DSC data was used to investigate the alloy’s solidification and phase transformation behavior. Subsequently, these samples were studied regarding their properties and microstructure by different analysis methods (EDX/WDX, EBSD, XRD). With increasing cooling rates the liquidus and solidus temperature are lowered, whereas the solidification interval is enlarged. A higher cooling rate is accompanied by a lower solidification time which results in a refinement of the dendritic microstructure. Furthermore, with rising cooling rates the microhardness increased. This provides the opportunity to make predictions from the applied cooling parameters upon the hardness and vice versa and enables one to draw first conclusions on the

Mechanism and kinetics of Fe, Cr, Mo and Mn atom interaction with molecular oxygen

International Nuclear Information System (INIS)

Akhmadov, U.S.; Zaslonko, I.S.; Smirnov, V.N.

1988-01-01

Rate constants of atomic interaction of some transition metals (Fe, Cr, Mo, Mn) with molecular oxygen are measured in shock waves using the resonance atomic-absorption method. A new method for determination of the parameter γ in the modified Lambert-Beer law D=ε(lN)γ is suggested and applied. Bond strength in CrO and MoO molecules is estimated

Evaluations of corrosion resistance of Ni-Cr plated and Zn-plated Fe Substrates Using an Electrolytic Corrosion Test

International Nuclear Information System (INIS)

Lee, Jaebong; Kim, Kyungwook; Park, Minwoo; Song, Taejun; Lee, Chaeseung; Lee, Euijong; Kim, Sangyeol

2013-01-01

An Eectrolytic Corrosion(EC) test method was evaluated by the comparison with Copper Accelerated Acetic Salt Spray(CASS) and Neutral Salt Spray(SS) tests. Those methods were applied in order to evaluate corrosion resistance of Ni-Cr plated and Zn-plated Fe substrates. The correlations between results obtained by different test methods were investigated. Results showed that the electrochemical method such as the EC test method was superior to the conventional methods such as CASS and SS, in terms of the quantitative accuracy and the test-time span. Furthermore, the EC test method provided the useful means to estimate the initiation of corrosion of each layer by monitoring the rest potentials of the coated layers such as Ni, Cr, and Zn on Fe substrate. With regard to test time spans, the EC test provided the 78 times and 182 times faster results than the CASS test in cases of Fe + 5μm Ni + 0.5 μm Cr and Fe + 20 μm Ni + 0.5 μm Cr respectively, while the EC test was 85 times faster results than the Salt Spray test in the case of Fe + 20 g/m 2 Zn. Therefore, the EC test can be the better method to evaluate the resistance to corrosion of coated layers than the conventional methods such as the SS test and the CASS

Model many-body Stoner Hamiltonian for binary FeCr alloys

Science.gov (United States)

Nguyen-Manh, D.; Dudarev, S. L.

2009-09-01

We derive a model tight-binding many-body d -electron Stoner Hamiltonian for FeCr binary alloys and investigate the sensitivity of its mean-field solutions to the choice of hopping integrals and the Stoner exchange parameters. By applying the local charge-neutrality condition within a self-consistent treatment we show that the negative enthalpy-of-mixing anomaly characterizing the alloy in the low chromium concentration limit is due entirely to the presence of the on-site exchange Stoner terms and that the occurrence of this anomaly is not specifically related to the choice of hopping integrals describing conventional chemical bonding between atoms in the alloy. The Bain transformation pathway computed, using the proposed model Hamiltonian, for the Fe15Cr alloy configuration is in excellent agreement with ab initio total-energy calculations. Our investigation also shows how the parameters of a tight-binding many-body model Hamiltonian for a magnetic alloy can be derived from the comparison of its mean-field solutions with other, more accurate, mean-field approximations (e.g., density-functional calculations), hence stimulating the development of large-scale computational algorithms for modeling radiation damage effects in magnetic alloys and steels.

Study of Fe-Ni-Cr-Mo-Si-B metallic glasses after neutron irradiation

International Nuclear Information System (INIS)

Sitek, J.; Miglierini, M.; Lipka, J.; Toth, I.

1992-01-01

Chromium containing metallic glasses are studied by transmission 57 Fe Moessbauer spectroscopy after neutron irradiation. Increasing number of non-magnetic chromium atoms causes a compositional dependence of Curie temperature. The unirradiated samples are fully paramagnetic for x≥10 at.% Cr at room temperature. Radiation induced changes in the magnetic structure imply a decrease of the Curie temperature. Ferromagnetic-to-paramagnetic transition is observed at room temperature for 8 at.% Cr after the exposure with 10 19 n/cm 2 . Using low temperature measurements, the Curie temperature for the sample containing 10 at.% Cr is estimated to be about 270 K. (orig.)

Nuclear Energy Advanced Modeling and Simulation (NEAMS) Accident Tolerant Fuels High Impact Problem: Coordinate Multiscale FeCrAl Modeling

Energy Technology Data Exchange (ETDEWEB)

Gamble, K. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, J. D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Andersson, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wirth, B. D. [Univ. of Tennessee, Knoxville, TN (United States)

2017-07-26

Since the events at the Fukushima-Daiichi nuclear power plant in March 2011 significant research has unfolded at national laboratories, universities and other institutions into alternative materials that have potential enhanced ac- cident tolerance when compared to traditional UO2 fuel zircaloy clad fuel rods. One of the potential replacement claddings are iron-chromium-alunimum (FeCrAl) alloys due to their increased oxidation resistance [1–4] and higher strength [1, 2]. While the oxidation characteristics of FeCrAl are a benefit for accident tolerance, the thermal neu- tron absorption cross section of FeCrAl is about ten times that of Zircaloy. This neutronic penalty necessitates thinner cladding. This allows for slightly larger pellets to give the same cold gap width in the rod. However, the slight increase in pellet diameter is not sufficient to compensate for the neutronic penalty and enriching the fuel beyond the current 5% limit appears to be necessary [5]. Current estimates indicate that this neutronic penalty will impose an increase in fuel cost of 15-35% [1, 2]. In addition to the neutronic disadvantage, it is anticipated that tritium release to the coolant will be larger because the permeability of hydrogen in FeCrAl is about 100 times higher than in Zircaloy [6]. Also, radiation-induced hardening and embrittlement of FeCrAl need to be fully characterized experimentally [7]. Due to the aggressive development schedule for inserting some of the potential materials into lead test assemblies or rods by 2022 [8] multiscale multiphysics modeling approaches have been used to provide insight into these the use of FeCrAl as a cladding material. The purpose of this letter report is to highlight the multiscale modeling effort for iron-chromium-alunimum (FeCrAl) cladding alloys as part of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program through its Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The approach taken throughout the HIP is to

Effects of Al addition and minor elements on oxidation behaviour of FeCr alloys

International Nuclear Information System (INIS)

Herbelin, J.M.; Mantel, M.

1995-01-01

It is shown that the addition of aluminium is very effective for the high temperature oxidation resistance of FeCr alloys. 1% aluminium produces a continuous protective Al 2 O 3 oxide for FeCr alloy that contains more than 13% of chromium. However this aluminium content is not enough for the high temperature resistance of thin foils and a 5% aluminium content is needed since the substrate plays the role of an aluminium reserve susceptible to oxidation. Impurity elements such as sulphur are detrimental and give rise to scaling of the oxide layer. Active elements such as Y, Ce, La, Zr are therefore necessary to tie up sulphur and increase the life of the alloys. (orig.)

Helium accumulation and bubble formation in FeCoNiCr alloy under high fluence He+ implantation

Science.gov (United States)

Chen, Da; Tong, Y.; Li, H.; Wang, J.; Zhao, Y. L.; Hu, Alice; Kai, J. J.

2018-04-01

Face-centered cubic (FCC) high-entropy alloys (HEA), as emerging alloys with equal-molar or near equal-molar constituents, show a promising radiation damage resistance under heavy ion bombardment, making them potential for structural material application in next-generation nuclear reactors, but the accumulation of light helium ions, a product of nuclear fission reaction, has not been studied. The present work experimentally studied the helium accumulation and bubble formation at implantation temperatures of 523 K, 573 K and 673 K in a homogenized FCC FeCoNiCr HEA, a HEA showing excellent radiation damage resistance under heavy ion irradiation. The size and population density of helium bubbles in FeCoNiCr samples were quantitatively analyzed through transmission electron microscopy (TEM), and the helium content existing in bubbles were estimated from a high-pressure Equation of State (EOS). We found that the helium diffusion in such condition was dominated by the self-interstitial/He replacement mechanism, and the corresponding activation energy in FeCoNiCr is comparable with the vacancy migration energy in Ni and austenitic stainless steel but only 14.3%, 31.4% and 51.4% of the accumulated helium precipitated into helium bubbles at 523 K, 573 K and 673 K, respectively, smaller than the pure Ni case. Importantly, the small bubble size suggested that FeCoNiCr HEA has a high resistance of helium bubble formation compared with Ni and steels.

Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

Science.gov (United States)

Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

2018-04-01

The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

Raman spectrometric determination of Pu(VI) and Pu(V) in nitric acid solutions

International Nuclear Information System (INIS)

Gantner, E.; Freudenberger, M.; Steinert, D.; Ache, H.J.

1987-03-01

The determination of Pu(VI) in nitric acid solutions by spontaneous Laser Raman Spectrometry (LRS) was investigated and a calibration curve was established using U(VI) as internal standard. In addition, the concentrations of Pu(VI) and Pu(V) as a function of time were measured by this method in Pu(VI) solutions of different acidity containing H 2 O 2 as the reducing agent. In solutions which are intensely coloured by the presence of Ru(NO) complexes Pu(VI) can also be determined by LRS using a Kr + laser as excitation source. In future experiments, the study of the Pu(IV)-interaction with Ru using LRS and spectrophotometry as analytical techniques is therefore intended. (orig.) [de

Characters of alloy Zr-0.4%Mo-0.5%Fe-0.5%Cr post heat treatment and cold rolling

International Nuclear Information System (INIS)

Sungkono; Siti Aidah

2014-01-01

Research and development of Zr-Mo-Fe-Cr alloys aimed to obtain PWR fuel element structure material with high burn up. In this study of the Zr-0.4%Mo-0.5%Fe-0.5%Cr alloys was prepared from zirconium sponge, molybdenum, iron and chromium powder. The alloy were heat treated at varying temperatures of 650 and 750 °C and retention time of 1, 1.5 and 2 hours. The objectives of this research was to obtain effect of thickness reduction on the character of Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy. The results of this experiment showed that the microstructures of Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy after heat treatment and cold rolling exhibits that the higher of the thickness reduction has applied on the alloy caused the microstructure to evolve from deformed equiaxial grains into flat bar grains and then into deformed flat bar grains. However, the higher of the temperature and the retention time then the larger grain structures so that the cold rolling causes the shape of the grains structure into a flat bar with a relatively larger size which affects the lower hardness. The Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy after heat treatment (650-750°C; 1.5-2 hours) can undergo cold deformation without cracking at a thickness reduction between 5 to 15%. (author)

TEM characterization of simultaneous triple ion implanted ODS Fe12Cr

International Nuclear Information System (INIS)

Castro, Vanessa de; Briceno, Martha; Lozano-Perez, Sergio; Trocellier, Patrick; Roberts, Steve G.; Pareja, Ramiro

2014-01-01

Understanding the behavior of oxide dispersion strengthened (ODS) ferritic/martensitic steels under irradiation is vital in the design of advanced fusion reactors. In this work, a simultaneous triple ion implanted ODS Fe12Cr steel was investigated by transmission electron microscopy in order to determine the effect of irradiation on the grain and dislocation structures, oxide nanoparticles and other secondary phases present in the steel. The ODS steel was irradiated at RT with Fe 8+ , He + and H + at the JANNUS-Saclay facility to a damage of 4.4 dpa. Results show that ODS nanoparticles appear very stable under these irradiation conditions

Equilibrium constant and nitrogen activity and the parameters of interaction eN(N), rN(N,Cr), rN(N,Mn) in high nitrogen steels of Fe-Cr-Mn-N type

International Nuclear Information System (INIS)

Svyazhin, A.G.; Siwka, J.; Rashev, T.

1999-01-01

In the paper a description of a thermodynamic of liquid solutions of Fe-Cr-Mn-N type with using a concept of parameters of an interaction has been presented. A temperature relationship of the equilibrium constant K N(Fe) and values of self interaction parameters e N (N) , r N (N,Cr) , r N (N,Mn) and t N (N,Cr,Cr) has been determined for mean values of temperatures of liquid metal equal 1990 K and 2090 K. By application of a theory of regular solutions those values were recalculated for a temperature 1873 K. (orig.)

Magnetic induction heating of FeCr nanocrystalline alloys

International Nuclear Information System (INIS)

Gómez-Polo, C.; Larumbe, S.; Pérez-Landazábal, J.I.; Pastor, J.M.; Olivera, J.; Soto-Armañanzas, J.

2012-01-01

In this work the thermal effects of magnetic induction heating in (FeCr) 73.5 Si 13.5 Cu 1 B 9 Nb 3 amorphous and nanocrystalline wires were analyzed. A single piece of wire was immersed in a glass capillary filled with water and subjected to an ac magnetic field (frequency, 320 kHz). The initial temperature rise enabled the determination of the effective Specific Absorption Rate (SAR). Maximum SAR values are achieved for those samples displaying high magnetic susceptibility, where the eddy current losses dominate the induction heating behavior. Moreover, the amorphous sample with Curie temperature around room temperature displays characteristic features of self-regulated hyperthermia. - Highlights: ► Amorphous and nanocrystalline Fe based alloys with tailored Curie temperature of the amorphous phase. ► Induction heating effects under the action of a ac magnetic field. ► Self-regulated characteristics based on the control of the Curie temperature. ► Dominant role of the eddy-current losses in the self-heating phenomena.

Benchmarking FeCr empirical potentials against density functional theory data

International Nuclear Information System (INIS)

Klaver, T P C; Bonny, G; Terentyev, D; Olsson, P

2010-01-01

Three semi-empirical force field FeCr potentials, two within the formalism of the two-band model and one within the formalism of the concentration dependent model, have been benchmarked against a wide variety of density functional theory (DFT) structures. The benchmarking allows an assessment of how reliable empirical potential results are in different areas relevant to radiation damage modelling. The DFT data consist of defect-free structures, structures with single interstitials and structures with small di- and tri-interstitial clusters. All three potentials reproduce the general trend of the heat of formation (h.o.f.) quite well. The most important shortcomings of the original two-band model potential are the low or even negative h.o.f. for Cr-rich structures and the lack of a strong repulsion when moving two solute Cr atoms from being second-nearest neighbours to nearest neighbours. The newer two-band model potential partly solves the first problem. The most important shortcoming in the concentration dependent model potential is the magnitude of the Cr–Cr repulsion, being too strong at short distances and mostly absent at longer distances. Both two-band model potentials do reproduce long-range Cr–Cr repulsion. For interstitials the two-band model potentials reproduce a number of Cr–interstitial binding energies surprisingly well, in contrast to the concentration dependent model potential. For Cr interacting with clusters, the result can sometimes be directly extrapolated from Cr interacting with single interstitials, both according to DFT and the three empirical potentials

Study of erythropoiesis with 59Fe and erythrocyte survival with 51Cr in aplastic anemia

International Nuclear Information System (INIS)

Avramova, D.; Karakostov, K.; Dimtrov, L.; Osmanliev, P.

1979-01-01

A study of erythropoiesis with 59 Fe and erythrocyte survival with 51 Cr was carried out in 25 patients with aplastic anemia and in a control group of 23 healthy persons. Bone marrow aplasia was uniform in all patients but differences in erythropoiesis were established. According to the state of erythropoiesis, the patients were divided into two groups: 1) patients with severe damage of erythropoiesis and 2) patients with preserved erythropoiesis. Erythrocyte survival in both groups was shortened. The data obtained correlate with the anemic syndrome and help to explain its pathogenesis. It is suggested that the investigation of erythropoiesis with 59 Fe and 51 Cr is of prognostic value. (author)

The influence of Cr content in Fe-Cr-Co alloys on the magnetic properties and Moessbauer effect

International Nuclear Information System (INIS)

Yan Yong; Sho Hanru; Li Dexin; Li Guodong; Li Dongshen; Zhen Jinshan

1986-01-01

Fe-xCr-8Co (x=24, 25, 27, 29 and 32 wt%) permanent magnetic alloys have been studied by Moessbauer effect, magnetic balance and vibrating-sample magnetometer. It is indicated that the optimum permanent magnetic properties obtained for the composition of the alloys at about x=27. The value of Cr content in these alloys sigificantly influences the average hyperfine field, the saturation magnetic moment, the proportion of paramagnetic phase and orientation of magnetic moment in these alloys. The intrinsic coercive force is gradually reduced with the temperature decreasing from 290 to 77 K. The paramagnetic peak in the spectrum disappears at about 125 K. The certain mechanism has been suggested to explain the experimental results. (Auth.)

Multi-scale modelling of radiation damage in Fe-Cr based on ab initio electronic structure calculations

International Nuclear Information System (INIS)

Olsson, Paer

2004-04-01

The efficiency of fast neutron reactors, such as for fusion, breeding and transmutation, depend strongly on the neutron radiation resistance of the materials used in the reactors. The binary Fe-Cr alloy, which has many attractive properties in this regard, is the base for the best steels of today which are, however, still not up to the required standards. Therefore, substantial effort has been devoted to finding new materials that can cope with the demands better. Experimental studies must be complemented with extensive theoretical modelling in order to understand the effects that different alloying elements has on the resistance properties of materials. To this end, the first steps of multi-scale modelling has been taken, starting out with ab initio calculations of the electronic structure of the complete concentration range range of the disordered binary Fe-C alloy. The mixing enthalpy of Fe-Cr has been quantitatively predicted and has, together with data from literature, been used in order to fit two sets of interatomic potentials for the purpose of simulating defect evolution with molecular dynamics and kinetic Monte-Carlo codes. These dedicated Fe-Cr alloy potentials are new and represent important additions to the pure element potentials that can be found in literature

Multi-scale modelling of radiation damage in Fe-Cr based on ab initio electronic structure calculations

Energy Technology Data Exchange (ETDEWEB)

Olsson, Paer

2004-04-01

The efficiency of fast neutron reactors, such as for fusion, breeding and transmutation, depend strongly on the neutron radiation resistance of the materials used in the reactors. The binary Fe-Cr alloy, which has many attractive properties in this regard, is the base for the best steels of today which are, however, still not up to the required standards. Therefore, substantial effort has been devoted to finding new materials that can cope with the demands better. Experimental studies must be complemented with extensive theoretical modelling in order to understand the effects that different alloying elements has on the resistance properties of materials. To this end, the first steps of multi-scale modelling has been taken, starting out with ab initio calculations of the electronic structure of the complete concentration range range of the disordered binary Fe-C alloy. The mixing enthalpy of Fe-Cr has been quantitatively predicted and has, together with data from literature, been used in order to fit two sets of interatomic potentials for the purpose of simulating defect evolution with molecular dynamics and kinetic Monte-Carlo codes. These dedicated Fe-Cr alloy potentials are new and represent important additions to the pure element potentials that can be found in literature.

The observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence

Science.gov (United States)

Silalahi, Marzuki; Purwanto, Setyo; Mujamilah; Dimyati, Arbi

2018-03-01

About the observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence. This paper reported about the observation of the resistivity change in the ultrasonic pre-treated Fe-Cr ODS sinter alloy under the influence of magnetic field at the Center for Science and Technology of Advanced Material, Nuclear Energy Agency of Indonesia. Fe-Cr ODS alloy were sinthesized by vacuum sintering of Fe- and Cr-powder dispersed Y2O3. However, before sintering the powder mixture was subjected to the irradiation process by ultrasonic for 50 hours at 20 kHz and then isostatic pressed up to 50.91 MPa to form a coin of 10 mm in diameter. LCR meassurement revealed the decreasing of resistivity about 3 times by increasing of applied magnetic field from 0 to 70 mT. In addition, VSM meassurement was performed on both as powder material and as sintered sample. The results showed increasing the magnetization with increasing magnetic field and the curve exhibits almost exact symmetry S-form with small hysterese indicating fast changing magnetization and demagnetization capability without energy loss. This opens strong speculations about the existence of magnetoresistant property of the material which is important for many application in field of sensors or electro magnetic valves.

Microautoradiography in studies of Pu(V) sorption by trace and fracture minerals in tuff

International Nuclear Information System (INIS)

Vaniman, D.; Furlano, A.; Chipera, S.; Thompson, J.; Triay, I.

1996-01-01

Microautoradiography was used to evaluate the mineralogic basis of Pu(V) retention by tuffs from Yucca Mountain, Nevada. Altered orthopyroxenes and oxide minerals are associated with high Pu retention but are limited to specific stratigraphic horizons. A weaker but more general association of Pu with smectite occurs in most samples. Thin-sections that cross fractures allow comparative studies of Pu retention by fracture-lining versus matrix minerals. Using Ag metal in emulsions as a measure of underlying Pu concentration, electron-microprobe analysis can quantify Pu retention along fracture walls and provide mineral/mineral Pu retention factors. For smectite-lined microfractures in zeolitized tuff, the smectite/clinoptilolite Pu retention factor is >80

Hydroponic phytoremediation of Cd, Cr, Ni, As, and Fe: can Helianthus annuus hyperaccumulate multiple heavy metals?

Science.gov (United States)

January, Mary C; Cutright, Teresa J; Van Keulen, Harry; Wei, Robert

2008-01-01

Sundance sunflowers were subjected to contaminated solutions containing 3, 4, or 5 heavy metals, with and without EDTA. The sunflowers exhibited a metal uptake preference of Cd=Cr>Ni, Cr>Cd>Ni>As and Fe>As>Cd>Ni>Cr without EDTA and Cr>Cd>Ni, Fe>As>Cd>Cr>Ni with EDTA. As uptake was not affected by other metals, but it decreased Cd and Ni concentration in the stems. The presence of Fe improved the translocation of the other metals regardless of whether EDTA was present. In general, EDTA served as a hindrance to metal uptake. For the experiment with all five heavy metals, EDTA decreased Cd in the roots and stems from 2.11 to 1.36 and from 2.83 to 2.3 2mg g(-1) biomass, respectively. For the same conditions, Ni in the stems decreased from 1.98 to 0.94 mg g(-1) total metal uptake decreased from 14.95 mg to 13.89 mg, and total biomass decreased from 2.38 g to 1.99 g. These results showed an overall negative effect in addition of EDTA. However it is unknown whether the negative effect was due to toxicity posed by EDTA or the breaking of phytochelatin-metal bonds. The most important finding was the ability of Sundance sunflowers to achieve hyperaccumulator status for both As and Cd under all conditions studied. Ni hyperaccumulator status was only achieved in the presence of three metals without EDTA.

Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration.

Science.gov (United States)

Dai, Chong; Zuo, Xiaobing; Cao, Bo; Hu, Yandi

2016-02-16

The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small-angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0-0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions' supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, the aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solutions. From solutions with 0-0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.

Influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers, Fe/Cr/Fe- and Fe/MgO/Fe multilayers; Untersuchung der Morphologie und magnetische Eigenschaften von ionenstrahl-gesputterten Eisen-Einzelschichten, Fe/Cr/Fe- und Fe/MgO/Fe-Schichtsystemen

Energy Technology Data Exchange (ETDEWEB)

Steeb, Alexandra

2007-04-05

In this PhD Thesis, the influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers on GaAs is examined. To analyze the structure of the produced iron films, low energy electron diffraction and scanning tunneling microscopy is employed. The utilized methods to investigate the magnetic properties are Kerr- and SQUID-magnetometry and ferromagnetic resonance. It is demonstrated that on untreated as well as on presputtered and heated GaAs substrates the sputtered iron films grow epitaxially. The least surface roughness of 1 A exhibit iron films grown on untreated GaAs, while iron films on heated GaAs have the highest roughness of 30 A. The largest crystal anisotropy constant is found for the presputtered GaAs/Fe-System. For this preparation method, two monolayers of iron are determined to be magnetically dead layers. At a film thickness of 100 A, 83% of the value for saturation magnetization of bulk iron are achieved. The small observed FMR-linewidths confirm the good bulk properties of the ion beam sputtered iron. Furthermore, an antiferromagnetic interlayer exchange coupling in sputtered Fe/Cr/Fe-films was achieved. For a thickness of 12 to 17 A of the chrome interlayer, a coupling strength up to 0.2 mJ/m{sup 2} is found. To account for the small coupling strength, a strong intermixing at the interface is assumed. Finally, epitaxial Fe/MgO/Fe/FeMn multilayers are deposited on GaAs. After the structuring, it is possible to detect tunneling processes in the tunneling contacts with current-voltage measurements. The tunnel magneto resistance values of 2% are small, which can be explained by the absence of sharp, well-defined interfaces between the Fe/FeMn and the Fe/MgO interfaces. These results demonstrate, that analog to MBE the ion beam sputtering method realizes good magnetic bulk properties. However, interface sensitive phenomena are weakened because of a strong intermixing at the interfaces. (orig.)

Structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the quaternary Heusler compound FeCrRuSi: A first-principles study.

Science.gov (United States)

Wang, Xiaotian; Khachai, Houari; Khenata, Rabah; Yuan, Hongkuan; Wang, Liying; Wang, Wenhong; Bouhemadou, Abdelmadjid; Hao, Liyu; Dai, Xuefang; Guo, Ruikang; Liu, Guodong; Cheng, Zhenxiang

2017-11-23

In this paper, we have investigated the structural, electronic, magnetic, half-metallic, mechanical, and thermodynamic properties of the equiatomic quaternary Heusler (EQH) compound FeCrRuSi using the density functional theory (DFT) and the quasi-harmonic Debye model. Our results reveal that FeCrRuSi is a half-metallic material (HMM) with a total magnetic moment of 2.0 μ B in agreement with the well-known Slater-Pauling rule M t  = Z t  - 24. Furthermore, the origin of the half-metallic band gap in FeCrRuSi is well studied through a schematic diagram of the possible d-d hybridization between Fe, Cr and Ru elements. The half-metallic behavior of FeCrRuSi can be maintained in a relatively wide range of variations of the lattice constant (5.5-5.8 Å) under uniform strain and the c/a ratio (0.96-1.05) under tetragonal distortion. The calculated phonon dispersion, cohesive and formation energies, and mechanical properties reveal that FeCrRuSi is stable with an EQH structure. Importantly, the compound of interest has been prepared and is found to exist in an EQH type structure with the presence of some B2 disorder. Moreover, the thermodynamic properties, such as the thermal expansion coefficient α, the heat capacity C V , the Grüneisen constant γ, and the Debye temperature Θ D are calculated.

Microstructural characterization of Y2O3 ODS-Fe-Cr model alloys

International Nuclear Information System (INIS)

Castro, V. de; Leguey, T.; Munoz, A.; Monge, M.A.; Pareja, R.; Marquis, E.A.; Lozano-Perez, S.; Jenkins, M.L.

2009-01-01

Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y 2 O 3 and the other Y 2 O 3 -free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes 3 C and M 23 C 6 carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M 23 C 6 carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.

Synthesis, characterization and surface modification of ZnCrFeO{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Hamed, Amal [Carnegie Laboratory of Physics, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN (United Kingdom); Fitzgerald, Alexander G., E-mail: a.g.fitzgerald@dundee.ac.uk [Carnegie Laboratory of Physics, School of Engineering, Physics and Mathematics, University of Dundee, Dundee, DD1 4HN (United Kingdom); Wang, Lijun; Gueorguieva, Mariana; Malik, Ritu; Melzer, Andreas [Institute for Medical Science and Technology, University of Dundee, Dundee, DD2 1FD (United Kingdom)

2013-04-01

The aim of this research was to investigate zinc chromium ferrite (ZnCrFeO{sub 4}) nanoparticles, synthesized using the sol gel technique with nanoparticle size controlled through a two-stage annealing process. Stage one was a low temperature firing which produced low quality nanocrystals with an average size of 15 nm. This was followed by a second firing stage at high temperature which enhanced the crystal quality. The nanoparticles were then coated with a bio-compatible shell to form a stable suspension in the ferrofluid carrier. The resulting nanoparticles were found by electron microscopy, atomic force microscopy and X-ray diffraction studies to have excellent crystal quality. The average size was 8.5 nm. Preliminary cell culture studies indicated the ZnCrFeO{sub 4} nanoparticles were non-toxic. The relatively high measured value of the relaxivity r{sub 2} showed that the nanoparticle coating was effective in substantially reducing aggregation and enhancing the properties of the nanoparticles associated with contrast enhancement in MRI. - Highlights: ► Novel two stage process produced optimal size and quality ZnCrFeO{sub 4} nanocrystals. ► We examined quality by electron and atomic force microscopy and X-ray diffraction. ► Average nanoparticle size of the, order of 10 nm, was determined by five methods. ► Relaxivity studies indicate possible use as negative contrast agent for MRI. ► Cell culture work shows that the nanocrystals have possible biomedical applications.

The role of Zr and Nb in oxidation/sulfidation behavior of Fe-Cr-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Natesan, K. (Argonne National Lab., IL (USA)); Baxter, D.J. (Argonne National Lab., IL (USA) INCO Alloy Ltd., Hereford, England (UK))

1990-11-01

05Structural Fe-Cr-Ni alloys may undergo rapid degradation at elevated temperatures unless protective surface oxide scales are formed and maintained. The ability of alloys to resist rapid degradation strongly depends on their Cr content and the chemistry of the exposure environment. Normally, 20 wt % Cr is required for service at temperatures up to 1000{degree}C; the presence of sulfur, however, inhibits formation of a protective surface oxide scale. The oxidation and sulfidation behavior of Fe-Cr-Ni alloys is examined over a wide temperature range (650 to 1000{degree}C), with particular emphasis on the effects of alloy Cr content and the radiation of reactive elements such as Nb and Zr. Both Nb and Zr are shown to promote protective oxidation behavior on the 12 wt % Cr alloy in oxidizing environments and to suppress sulfidation in mixed oxygen/sulfur environments. Additions of Nb and Zr at 3 wt % level resulted in stabilization of Cr{sub 2}O{sub 3} scale and led to a barrier layer of Nb- or Zr-rich oxide at the scale/metal interface, which acted to minimize the transport of base metal cations across the scale. Oxide scales were preformed in sulfur-free environments and subsequently exposed to oxygen/sulfur mixed-gas atmospheres. Preformed scales were found to delay the onset of breakaway corrosion. Corrosions test results obtained under isothermal and thermal cycling conditions are presented. 58 refs., 55 figs., 8 tabs.

Infiltrated SrTiO₃:FeCr-based anodes for metalsupported SOFC

DEFF Research Database (Denmark)

Blennow Tullmar, Peter; Persson, Åsa Helen; Nielsen, Jimmi

2012-01-01

The concept of using highly electronically conducting backbones with subsequent infiltration of electrocatalytic active materials, has recently been used to develop an alternative SOFC design based on a ferritic stainless steel support. The metal-supported SOFC is comprised of porous and highly e...... changes occurring in the anode layer during testing. The results indicate that the STN component in the anode seems to have a positive effect on the corrosion stability of the FeCr-particles in the anode layer.......) and FeCr. Electrochemical characterization and post test SEM analysis have been used to get an insight into the possible degradation mechanisms of this novel electrode infiltrated with Gd-doped CeO2 and Ni. Accelerated oxidation/corrosion experiments have been conducted to evaluate the microstructural...

Preparation, characterization and enhanced adsorption performance for Cr(VI) of mesoporous NiFe2O4 by twice pore-forming method

International Nuclear Information System (INIS)

Jia, Zhigang; Peng, Kuankuan; Xu, Lixin

2012-01-01

Magnetic mesoporous NiFe 2 O 4 with higher surface area has been prepared by the twice pore-forming method, including the calcination of the oxalate precursor and leaching of ZnO pore-forming agent. The X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and BET surface area measurement are used to evaluate the pore structural parameters and surface chemistry of the adsorbent respectively. The pore-forming mechanism is proposed based on the experimental results. The adsorption behavior of mesoporous NiFe 2 O 4 for Cr(VI) is investigated in detail. The results show that kinetic data follow a pseudo-second-order model and equilibrium data are well fitted by the Langmuir model. The maximum adsorption capacity is 43.68 mg g −1 at pH 2. The removal for Cr(VI) is mainly physisorption process derived from coulombic interaction. The as-prepared TPF-NiFe 2 O 4 is promising as sorbent for Cr(VI) removal because of its higher adsorption capacity, separation convenience and highly efficient reusability. -- Highlights: ► The increase of BET area was realized by leaching of ZnO from mesoporous ZnO/NiFe 2 O 4 . ► TPF-NiFe 2 O 4 demenstrates higher adsorption capacity for Cr(VI) in aqueous solution. ► TPF-NiFe 2 O 4 with magnetic sensitivity is promosing for Cr(VI) removal. ► The used TPF-NiFe 2 O 4 adsorbent can be recycled.

Determination of chemical activities of Fe, Cr, Ni and Mn in stainless steel 316 by Knudsen effusion cell mass spectrometry

International Nuclear Information System (INIS)

Venugopal, V.; Kulkarni, S.G.; Subbanna, C.S.; Sood, D.D.

1995-01-01

Cold-worked austenitic stainless steel of the type AISI 316 is being used as the cladding and wrapper materials in fast reactor fuel pins. Knowledge of the thermodynamic activities of the steel constituents is necessary to predict the possibility of fuel-cladding, coolant-cladding or fission product-cladding chemical reactions. The thermodynamic activities of Fe, Cr, Ni and Mn for stainless steel 316 were determined by measuring their partial pressures in the temperature range 1293-2120 K, using Knudsen effusion cell mass spectrometry. High purity Ag was used as an internal calibrant. The chemical activities of Fe (a Fe ), Cr (a Cr ), Ni (a Ni ) and Mn (a Mn ) were evaluated using literature data for the vapour pressures of pure metals. log a Fe ±0.18=-1.586+2074/T (T=1293-1872 K)log a Cr ±0.30=-2.350+2612/T (T=1293-2120 K)log a Ni ±0.20=-2.140+1794/T (T=1468-1974 K)log a Mn ±0.23=-2.041-5478/T (T=1302-1894 K) ((orig.))

Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part II: Cavitation Erosion

Directory of Open Access Journals (Sweden)

D. Kekes

2014-12-01

Full Text Available Composite coatings with five different proportions of WC-Co/Cr and NiCrFeBSiC components were deposited on stainless steel by HVOF spraying. Cavitation erosion tests were performed and the material removal micro-mechanisms were identified by SEM of both the eroded areas and the specimens’ cross-sections. Waves’ propagation and deflection at the weak interfaces within the coatings resulted in local tensile stresses perpendicular to the interface direction that eventually led to material removal. Such weak interfaces are the boundaries of the carbide particles with the metal binder within the same splat, those between splats along the same layer and those between successively deposited layers.

Studies of Binary Complexes of Tripodal Ligand cis,cis-1,3,5-tris(methylaminocyclohexane with Cr(III and Fe(III

Directory of Open Access Journals (Sweden)

S. Esakki Muthu

2005-01-01

Full Text Available The formation of binary complexes of Cr(III and Fe(III with a tripodal ligand cis,cis-1,3,5-tris(methylaminocyclohexane (tmach (L has been investigated in solution. The overall stability constants of tmach with Cr(III and Fe(III were determined by potentiometric method at an ionic strength of 0.1 M NaClO4 at 25±1°C in aqueous medium. The formation of species like MLH25+, MLH4+, ML3+, ML(OH2+ and ML(OH3 were observed. Fe(III was found to form more stable complexes than Cr(III. Molecular mechanics calculations were performed to explain the mode of coordination in solution.

Changes in cluster magnetism and suppression of local superconductivity in amorphous FeCrB alloy irradiated by Ar{sup +} ions

Energy Technology Data Exchange (ETDEWEB)

Okunev, V.D., E-mail: okunev@mail.fti.ac.donetsk.ua [Donetsk Physiko-Technical Institute, Ukrainian Academy of Sciences, av. Nauki 46, 03028 Kiev (Ukraine); Samoilenko, Z.A. [Donetsk Physiko-Technical Institute, Ukrainian Academy of Sciences, av. Nauki 46, 03028 Kiev (Ukraine); Szymczak, H.; Szewczyk, A.; Szymczak, R.; Lewandowski, S.J.; Aleshkevych, P.; Malinowski, A.; Gierłowski, P.; Więckowski, J. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Wolny-Marszałek, M.; Jeżabek, M. [Institute of Nuclear Physics, Polish Academy of Sciences, Krakow (Poland); Varyukhin, V.N. [Donetsk Physiko-Technical Institute, Ukrainian Academy of Sciences, av. Nauki 46, 03028 Kiev (Ukraine); Antoshina, I.A. [Obninsk State Technical University of Atomic Energy, 249020 Obninsk (Russian Federation)

2016-02-01

We show that cluster magnetism in ferromagnetic amorphous Fe{sub 67}Cr{sub 18}B{sub 15} alloy is related to the presence of large, D=150–250 Å, α-(Fe Cr) clusters responsible for basic changes in cluster magnetism, small, D=30–100 Å, α-(Fe, Cr) and Fe{sub 3}B clusters and subcluster atomic α-(Fe, Cr, B) groupings, D=10–20 Å, in disordered intercluster medium. For initial sample and irradiated one (Φ=1.5×10{sup 18} ions/cm{sup 2}) superconductivity exists in the cluster shells of metallic α-(Fe, Cr) phase where ferromagnetism of iron is counterbalanced by antiferromagnetism of chromium. At Φ=3×10{sup 18} ions/cm{sup 2}, the internal stresses intensify and the process of iron and chromium phase separation, favorable for mesoscopic superconductivity, changes for inverse one promoting more homogeneous distribution of iron and chromium in the clusters as well as gigantic (twice as much) increase in density of the samples. As a result, in the cluster shells ferromagnetism is restored leading to the increase in magnetization of the sample and suppression of local superconductivity. For initial samples, the temperature dependence of resistivity ρ(T)~T{sup 2} is determined by the electron scattering on quantum defects. In strongly inhomogeneous samples, after irradiation by fluence Φ=1.5×10{sup 18} ions/cm{sup 2}, the transition to a dependence ρ(T)~T{sup 1/2} is caused by the effects of weak localization. In more homogeneous samples, at Φ=3×10{sup 18} ions/cm{sup 2}, a return to the dependence ρ(T)~T{sup 2} is observed. - Highlights: • The samples at high dose of ion irradiation become more homogeneous. • Gigantic increase in density of the samples (twice as much) is observed. • Ferromagnetism in large Fe–Cr clusters is restored. • Ferromagnetism of Fe–Cr clusters suppresses local superconductivity in them. • The participation of quantum defects in scattering of electrons is returned.

Microstructure Evolution and Chemical Analysis on Carbon Steels and Fe-Cr-Mo Alloys after FAC Simulation Tests

International Nuclear Information System (INIS)

Kim, Seunghyun; Kim, Taeho; Lee, Yun Ju; Kim, Ji Hyun

2017-01-01

Flow-accelerated corrosion (FAC) is an environment assisted degradation of structural materials, which usually occurs in pipelines of power plants. There have been many studies to investigate the fundamental mechanism and corresponding countermeasures against FAC, and recently the carbon steels have been replaced by ASTM A 335 P22, which contains approximately 2.2 wt.% of Cr and 1 wt.% of Mo. By enhancing passivity of P22 by Cr, it is reported that FAC rate has been greatly reduced. However, while corrosion behavior of Fe-based alloys is relatively well known, their behavior under high-temperature flowing water is not well investigated. In other words, effects of Cr and its corrosion and oxidation behavior is not clearly revealed. Furthermore, it is known that Mo enhances the pitting corrosion resistance of alloys however its mechanism is not clearly investigated. Recently, replacement of Mo in alloy contents has been widely studied because of the cost of Mo. Carbon steels undergo severe environmental-assisted degradation behavior so called FAC, and as its countermeasure the carbon steel has been replaced by P22 which contains Cr and Mo. It is generally known that Cr and Mo enhances passivity of Fe-based alloys however their corrosion and oxidation behavior has not been fully investigated especially in high-temperature flowing water environments. In this study, we employed HRTEM and synchrotron XAS techniques in order to investigate detailed microstructure evolution and chemical bonding of the commercialized carbon steel and the Fe-Cr-Mo alloys. From the analysis, it is found that while carbon steels exhibit porous oxide P22 exhibit oxide structures with thin Cr-rich oxide and spinel. Therefore, carbon steel undergoes severe FAC compared to P22 however effects of Cr and Mo and their behavior in high-temperature flowing water will be investigated.

First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

Directory of Open Access Journals (Sweden)

Hui Huang

2016-07-01

Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

Influence of Fe(Cr) miscibility on thin film grain size and stress

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuyang; Kaub, Tyler; Martens, Richard L.; Thompson, Gregory B., E-mail: gthompson@eng.ua.edu

2016-08-01

During the post coalescence portion of thin film deposition, thin film stress is related to the grain size and adatom mobility of the depositing material. Using a Fe(Cr) alloy thin film, the manipulation of the tensile stress for thick films was studied as a function of Cr solute content up to 8 at.%. Solute concentrations up to 4 at.% resulted in an approximate 50% increase in grain size that resulted in a reduction of the tensile stress to be lower than either elemental film. Upon increasing the Cr content, the grain size refined and the tensile stress of the films increased. Atom probe characterization of the grain boundaries confirmed Cr chemical partitioning which refined the grain size and altered the film's texture, both of which contributed to the change in film stress. The use of intrinsic segregation, rather than deposition processing parameters, appears to be another viable option for regulating film stress. - Highlights: • Solute segregation to regulate grain size in controlling film stress • Quantification of Cr interfacial excess as a function of alloy content • Quantification of texture fiber alignment as a function of Cr content.

TEM characterization of simultaneous triple ion implanted ODS Fe12Cr

Energy Technology Data Exchange (ETDEWEB)

Castro, Vanessa de, E-mail: vanessa.decastro@uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganés, Madrid (Spain); Briceno, Martha [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Johnson Matthey Technology Centre, Blount’s Court Rd, Sonning Common RG4 9NH (United Kingdom); Lozano-Perez, Sergio [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Trocellier, Patrick [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Roberts, Steve G. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Pareja, Ramiro [Departamento de Física, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganés, Madrid (Spain)

2014-12-15

Understanding the behavior of oxide dispersion strengthened (ODS) ferritic/martensitic steels under irradiation is vital in the design of advanced fusion reactors. In this work, a simultaneous triple ion implanted ODS Fe12Cr steel was investigated by transmission electron microscopy in order to determine the effect of irradiation on the grain and dislocation structures, oxide nanoparticles and other secondary phases present in the steel. The ODS steel was irradiated at RT with Fe{sup 8+}, He{sup +} and H{sup +} at the JANNUS-Saclay facility to a damage of 4.4 dpa. Results show that ODS nanoparticles appear very stable under these irradiation conditions.

Hardening of Fe-Cr-Mn steels cold plastic working

International Nuclear Information System (INIS)

Malinov, L.S.; Konop-Lyashko, V.I.; Nikoporets, N.M.

1983-01-01

The dependence is established between the level of proper-- ties obtained after cold plastic working and development of martensite transformations when loading in Fe-Cr-Mn steels containing 0.1-0.5% C, 13% Cr, 8-12% Mn, as well as in a number of complex alloyed steels. It is shown that the highest level of mechanical properties can be obtained after cold plastic working only in steels with definite austenite stability. Cold plastic working can both activize and stabilize austenite relatively to martensite formation during loading. The first thing is found when under the effect of preliminary cold working dislocation splitting takes place, as well as the formation of a small amount of E-phase and martensite. The second thing manifests itself when under the effect of cold working performed above Md (Md<20 deg C) cell dislocation structure is formed and dislocation pinning takes place

The effect of small 4th element alloying additions on the calculated phase stability in the Fe-Cr-Ni system

International Nuclear Information System (INIS)

Watkin, J.S.

1979-01-01

Recent studies into the void swelling of Fe-Cr-Ni alloys have revealed that the magnitude of swelling depends upon alloy constitution and this together with the fact that minor element additions also play a major role in swelling necessitate a detailed knowledge of the influence of small 4th element additions on phase stability. In this paper the effects of additions of Nb, Ti, Al, Mo, Co and C to the Fe-Cr-Ni ternary are assessed by calculation. They confirm the ferritising tendencies of Nb, Ti and Al and the strong austenitising effect of C. Confirmation is also found for the scaling factors in the equivalent Ni and Cr equations in common usage and the paper presents Fe-Cr-Ni ternary sections at 400, 550 and 700 0 C modified for 1 at.% addition of each of the above elements. (orig.) [de

Fe, Cr, Ni, Cu, Mg, Al, Ti, and S contents in plants and soil of heaps of nickel smelting works

Energy Technology Data Exchange (ETDEWEB)

Banasova, V; Hajduk, J

1977-01-01

The writers established the Fe, Ce, Cr, Ni, Ca, Mg, Al, Ti and S contents in the neopedon of heaps piling up from processing of nickel ore as well as in the plants: Cardaria draba, Salsola cali, Agropyrum repens, Bromus erectus, Calamagrostis epigeios, Cynodon dactylon and Matricaria inodora, growing on such heaps. Ca, Mg and S contents were found to be higher in dicotyledons and Fe, Al, Ti, Ni and Cr contents higher in monocotyledons. The analyzed dicotyledons appeared to be concentrators of Ca and S. Highest Fe, Al, Ti, Ni and Cr contents were found in individuals of the species Agropyrum repens. The neopedon as well as the plants had extraordinarily high Cr concentrations. The species Salsola cali has been found to possess an unusually higher affinity to the dump substrate after processing of nickel ore and to be a concentrator of Mg. 16 references, 1 table.

Assessment of the concentration of Cr, Mn and Fe in sediment using ...

African Journals Online (AJOL)

In the present study, laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of levels of Cr, Mn and Fe in sediment samples and the results have been compared with that of flame-atomic absorption spectroscopy (F-AAS). Fourteen sediment samples were collected from Tinishu Akaki River ...

Study of the microstructure and of microhardness variation of a Ni-Fe-Cr austenitic alloy by niobium

International Nuclear Information System (INIS)

Carvalho e Camargo, M.U. de; Lucki, G.

1979-01-01

The mechanisms of hardening and corrosion resistance increase in Ni-Fe-Cr austenitic stainless steels by Nb additions are of interest to nuclear technology Niobium additions to a 321 type stainless steel were made in order to study the microhardness, electrical resistivity and metallography. Experimental measurements results are shown. The effect of Nb additions as a micro-alloying element and the thermal and mechanical processes (cold working in particular) in the microstructure and microhardness properties of the 11% Ni - 70%Fe - 17% Cr austenitic alloys were studied. (Author) [pt

Distribution of Cr atoms in the surface zone of Fe-rich Fe–Cr alloys quenched into various media: Mössbauer spectroscopic study

International Nuclear Information System (INIS)

Dubiel, Stanisław M.; Cieślak, Jakub; Żukrowski, Jan

2015-01-01

Graphical abstract: Chromium depletion, Δx = x_k − x, in Fe_1_0_0_−_xCr_x (x = 2.2, 3.9, 6.4, 8.5, 10.25, 10.75, 14.9, 15.15) alloys quenched into LN (left panel) and those quenched onto brass (right panel) as found from CEMS (pre surface zone) and TRANS (bulk) Mössbauer spectra (x_k – Cr content in the pre surface or bulk as estimated from the average hyperfine field found for the quenched samples). - Highlights: • Effect of quenching media on Cr atom distribution in Fe–Cr alloys was determined. • Significant differences between bulk and pre surface zone were revealed. • Quenching into water and LH resulted in surface oxidation of samples. • Samples quenched onto a block of brass were not oxidized. - Abstract: Effect of a quenching medium (water, liquid nitrogen and block of brass) on a distribution of Cr atoms in the surface zone of Fe_1_0_0_−_xCr_x (x ≤ 19) alloys was studied with the Mössbauer spectroscopy. The distribution of Cr atoms was expressed in terms of the Cowley–Warren short-range order (SRO) parameters: 〈α_1〉 for the first neighbor-shell, 〈α_2〉 for the second neighbor-shell and 〈α_1_2〉 for both neighbor-shells. It was revealed that none of the quenching media resulted in a random distribution of atoms, yet the degree of randomness was the highest for the samples quenched onto the block of brass. The quenching into water and liquid nitrogen caused a partial oxidation of samples’ surface accompanied by a chromium depletion of the bulk. Quantitative analysis of various phases in the studied samples both in their bulk as well as in pre surface zones was carried out.

Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2015-10-25

Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

International Nuclear Information System (INIS)

Field, Kevin G.; Gussev, Maxim N.; Hu, Xunxiang; Yamamoto, Yukinori

2015-01-01

The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hu, Xunxiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-30

The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

Pulse electrodeposition of Fe-Ni-Cr alloys

International Nuclear Information System (INIS)

Adelkhani, H.

2000-01-01

Pulse Electroplating is a relativity new technique in electrodeposition of pure metals and alloys which has resulted in a number of improvement over the traditional direct current method. Among these are a better composition control, lower porosity, reduction of internal stresses and hydrogen content as well as other impurities. In this work Pulse plating of Fe-Ni-Cr alloys has been investigated by using a series of planned experiments. A domain of Pulse parameters, such a pulse frequency, pulse duration, current density and batch condition such as Ph, temperature and has been defined where the coating quality is optimal. The result obtained were Compared with those of D C electroplating and finally a number of recommendations are made for future works towards a semi-industrial process

Fabrication of Fe-Cr-Mo powder metallurgy steel via a mechanical-alloying process

Science.gov (United States)

Park, Jooyoung; Jeong, Gowoon; Kang, Singon; Lee, Seok-Jae; Choi, Hyunjoo

2015-11-01

In this study, we employed a mechanical-alloying process to manufacture low-alloy CrL and CrM steel powders that have similar specifications to their water-atomized counterparts. X-ray diffraction showed that Mo and Cr are alloyed in Fe after four cycles of planetary milling for 1 h at 150 RPM with 15-min pauses between the cycles (designated as P2C4 process). Furthermore, the measured powder size was found to be similar to that of the water-atomized counterparts according to both scanning electron microscope images and laser particle size analysis. The samples were sintered at 1120 °C, after which the P2C4-milled CrL showed similar hardness to that of water-atomized CrL, whereas the P2C4-milled CrM showed about 45% lower hardness than that of its water-atomized counterpart. Water-atomized CrM consists of a well-developed lathtype microstructure (bainite or martensite), while a higher fraction of polygonal ferrite is observed in P2C4-milled CrM. This phase difference causes the reduction of hardness in the P2C4-milled CrM, implying that the phase transformation behavior of specimens produced via powder metallurgy is influenced by the powder fabrication method.

Effect of alloying elements on σ phase formation in Fe-Cr-Mn alloys

International Nuclear Information System (INIS)

Okazaki, Yoshimitsu; Miyahara, Kazuya; Hosoi, Yuzo; Tanino, Mitsuru; Komatsu, Hazime.

1989-01-01

Alloys of Fe-(8∼12%) Cr-(5∼30%) Mn were solution-treated at 1373 K for 3.6 ks, followed by cold-working of 50% reduction. Both solution-treated and 50% cold-worked materials were aged in the temperature range from 773 to 973 K for 3.6 x 10 3 ks. The identification of σ phase formation was made by using X-ray diffraction from the electrolytically extracted residues of the aged specimens. The region of σ phase formation determined by the present work is wider than that on the phase diagram already reported. It is to be noted that Mn promotes markedly the σ phase formation, and that three different types of σ phase formation are observed depending on Mn content: α→γ + α→γ + α + σ in 10% Mn, α→γ + σ in 15 to 20% Mn alloys, α→χ(Chi) →χ + σ + γ in 25 to 30% Mn alloys. An average electron concentration (e/a) in the σ phase was estimated by quantitative analysis of alloying elements using EPMA. The e/a value in the σ phase formed in Fe-(12∼16%) Cr-Mn alloys aged at 873 K for 3.6 x 10 3 ks is about 7.3, which is independent of Mn content. In order to prevent σ phase formation in Fe-12% Cr-15% Mn alloy, the value of Ni * eq of 11 (Ni * eq = Ni + 30(C) + 25(N)) is required. (author)

Structure and magnetic properties of Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al, (0 ≤ x ≤ 1) Heusler alloys prepared by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Yogesh, E-mail: 123209001_yogesh@manit.ac.in [Department of Materials Science & Metallurgical Engineering, Ceramic & Powder Metallurgy Laboratory, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Vajpai, Sanjay Kumar, E-mail: vajpaisk@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Srivastava, Sanjay, E-mail: s.srivastava.msme@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India)

2017-07-01

Highlights: • A series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy by powder metallurgy. • Effect of substitution of Fe for Cr on the microstructure and magnetic properties. • Increasing amounts of B2 type disordered structure with increasing Fe content. • Enhanced Ms, Mr, Hc, and Tc with increasing Fe content. • Relative magnetic anisotropy decreased with increasing Fe content. - Abstract: In the present study, a series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders were successfully prepared by high energy ball milling and the effect of substitution of Fe for Cr on the microstructure and magnetic properties was investigated in detail. The Co{sub 2}CrAl alloy powder consisted of only A2 type disordered structure whereas the substitution of Cr by Fe led to the appearance of increasing amounts of B2 type disordered structure along with A2 type structure. All the Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders demonstrated high spontaneous magnetization together with a very small hysteresis losses. The saturation magnetization, remanence, coercivity, and Curie temperature increased with increasing Fe content. The increasing magnetization with increasing Fe content was attributed to the replacement of antiferromagnetic Cr by strongly ferromagnetic Fe and an increasing amounts of relatively more ordered, atomically as well as ferromagnetically, B2 structure as compared to that of A2 phase. The increment in remanence and coercivity with increasing Fe content were associated with the variation in microstructural characteristics, such as grain size, lattice defects, and the presence of small amounts of magnetic/nonmagnetic secondary phases. The increment in Curie temperature with increasing Fe content was attributed to the enhancement of d-d exchange interaction due to the possible occupancy of vacant sites by Fe atoms. All the Heusler alloys indicated extremely low magnetic anisotropy and the

Ab initio and Atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

Science.gov (United States)

Piochaud, J. B.; Becquart, C. S.; Domain, C.

2014-06-01

Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multiscale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe70Cr20Ni10). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT calculations. The point defect properties in the Fe70Cr20Ni10, and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed.

Impact of the Volatile Cr-species' Attack on the Conductivity of La(Ni,Fe)O3

NARCIS (Netherlands)

Stodolny, M.K.; Boukamp, Bernard A.; van Berkel, Frans

2011-01-01

This study demonstrates the detrimental impact of Cr on the electronic conductivity of a $LaNi_{0.6}Fe_{0.4}O_3$ (LNF) porous cathode layer at 800 ºC. Vapor transport of Cr-species, originating from a porous metallic foam, and subsequent reaction with LNF results in a decrease of the electronic

Study of irradiated F82H steel and its model Fe-Cr alloy by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Huang, S.S.; Kitao, S.; Xu, Q.; Sato, K.; Yoshiie, T.

2013-01-01

In this work, Moessbauer spectroscopy which is a super-precision tool was conducted on F82H and its model Fe-Cr alloys before and after irradiation to take a further look on the interaction between carbides and point defects and Cr effect on microstructural evolution during irradiation in void incubation period. (J.P.N.)

Radiotracer study of the adsorption of Fe(III), Cr(III) and Cd(II) on natural and chemically modified Slovak zeolite

International Nuclear Information System (INIS)

Foeldesova, M.; Dillinger, P.; Lukac, P.

1998-01-01

In order to minimize the contamination of environment with metals in ionic form the more types of natural and chemically modified zeolites were examined to their uptake of Fe(III), Cr(III) and Cd(II) from water solutions by batch radio-exchange equilibration method. In this study was used zeolitic tuff from deposit Nizny Hrabovec (content of clinoptilolite 50-70%) with the grain size from 1.2 to 2.2 mm. The granules of zeolite were modified with the following NaOH solutions: ).5, 1, 2 and 4 mol.l -1 at 80 grad C for 4 hours. The sorption of Fe, Cr and Cd ions on all types of zeolites was studied by radio-exchange method and the sorption of Fe and Cr also flame atomic absorption method. From sorption curves the sorption coefficients were calculated. The results obtained in this work show that zeolites modified with NaOH solution are suitable for adsorption of Fe(III), Cr(III) and Cd(II) from underwater, waste water, feed water and coolant water from nuclear plants. The adsorbed zeolites can be solidified by conventional way

Electrical and optical properties of Cr and Fe implanted n-GaN

International Nuclear Information System (INIS)

Polyakov, A.Y.; Smirnov, N.B.; Govorkov, A.V.; Pashkova, N.V.; Shlensky, A.A.; Pearton, S.J.; Overberg, M.E.; Abernathy, C.R.; Zavada, J.M.; Wilson, R.G.

2003-01-01

Deep levels introduced into n-GaN films by Fe and Cr implantation have been studied by means of optical absorption and microcathodoluminescence spectroscopy measurements and by deep level transient spectroscopy, admittance spectroscopy, and capacitance-voltage profiling. The results are compared with previous measurements on Mn and Co implanted GaN. It is shown that the acceptor levels of substitutional Mn, Co, Fe, and Cr in n-GaN are located, respectively, near E v +1.6 eV, E v +1.7 eV, E v +1.8 eV, and E v +2 eV, the trend being similar to that observed in GaAs, GaP, and InP. The Fermi level in the implanted region is pinned near deep electron traps at E c -0.5 eV that are tentatively attributed to complexes between substitutional transition metal ions and native defects such as nitrogen vacancies. It is shown that for all implanted species after 700 deg. C annealing a damaged region with relatively high resistivity is formed down to the depth of about 1 μm much, exceeding the projected range of implanted ions. This region is enriched with radiation-damage-related defects and is most likely formed by outdiffusion of these defects from the implanted region during annealing. The thickness of this damaged region is shown to be the lowest for Cr implantation

The elements distribution of Fe, Cd, Ca, Co and Cr on the well water and river in area Wonosari Gunung Kidul

International Nuclear Information System (INIS)

Rosidi; Agus Taftazani; Sukirno

2010-01-01

The analysis of Fe, Cd, Ca, Co and Cr on the well water and river were detected by γ spectrometer with HPGe detector using NAA method. The main objective of this research was carried out to characterize the Fe, Cd, Ca, Co and Cr on the well water and river in area Gunung Kidul Yogyakarta, which accommodate of the present of environment data in support the clean water program. The result indicated that concentration of elements in well and river water at the Wonosari were still in standard level by Govenor of Daerah Istimewa Yogyakarta no 214/KPTS/1991, were Cd = 0,005 mg/L; Ca = 200 mg/L; Fe = 0,5 mg/L; Co = 0,2 mg/L and Cr = 0,050 mg/L. The concentration in water of Cd, Fe, Ca, Co, and Cr were (0.0002-0.006), (16-40), (5-20), (0.0002-0.37) and (0.0003-0.005) mg/L respectively. The result of analysis give the information that these elements concentration were still proper to use for domestic activities. (author)

Comparative concentration analysis of Cr and Co in FeSi2 films performed by ERDA and RBS

International Nuclear Information System (INIS)

Bohne, W.; Reinsperger, G.-U.; Roehrich, J.; Roeschert, G.; Selle, B.; Stauss, P.

2000-01-01

Thin films of β-FeSi 2 doped by Co or Cr were grown on Si substrates by molecular beam epitaxy (MBE) using three separately controlled evaporation sources. The dopant concentration was measured concurrently by heavy-ion ERDA with 129 Xe ions of 140-250 MeV, by heavy-ion RBS with 15 MeV 14 N and by standard RBS with 1.4 MeV 4 He ions. Among these techniques, the TOF-ERDA was most powerful in providing a high mass resolution and a low detection limit for Co and Cr (∼0.1 at.%). Because of the complete overlap of the dopant signals with the Fe signal the standard RBS spectra were evaluated by relying on the differences between the scattering cross-sections from the dopant atoms and Fe. This approach proved to be applicable as far as the dopants had a constant depth profile with sufficiently high concentration. For Cr concentrations exceeding the miscibility limit the RBS results deviate significantly from those of ERDA due to increasing dopant depth inhomogeneities

Microstructure and Tribological Properties of AlCoCrFeNiTi0.5 High-Entropy Alloy in Hydrogen Peroxide Solution

Science.gov (United States)

Yu, Y.; Liu, W. M.; Zhang, T. B.; Li, J. S.; Wang, J.; Kou, H. C.; Li, J.

2014-01-01

Microstructure and tribological properties of an AlCoCrFeNiTi0.5 high-entropy alloy in high-concentration hydrogen peroxide solution were investigated in this work. The results show that the sigma phase precipitates and the content of bcc2 decrease during the annealing process. Meanwhile, the complex construction of the interdendrite region changes into simple isolated-island shape, and much more spherical precipitates are formed. Those changes of microstructure during the annealing process lead to the increase of hardness of this alloy. In the testing conditions, the AlCoCrFeNiTi0.5 alloy shows smoother worn surfaces and steadier coefficient of friction curves than does the 1Cr18Ni9Ti stainless steel, and SiC ceramic preserves better wear resistance than ZrO2 ceramic. After annealing, the wear resistance of the AlCoCrFeNiTi0.5 alloy increases coupled with SiC counterface but decreases with ZrO2 counterface.

Influence of irradiation with energy-rich particles on the hardness of the Fe-Cr alloy; Einfluss der Bestrahlung mit energiereichen Teilchen auf die Haerte von Fe-Cr-Legierungen

Energy Technology Data Exchange (ETDEWEB)

Heintze, Cornelia

2013-01-14

Ferritic/martensitic and oxide dispersion strengthened ferritic/martensitic steels are candidate structural materials for components exposed to high neutron fluxes in future nuclear applications like fusion and generation IV fission reactors. The ductilebrittle transition and its shift to higher temperatures which is predominantly caused by irradiation hardening are main concerns for these materials. In the present work, the irradiation behaviour of binary Fe-Cr model alloys, which represent a simplified model for ferritic/martensitic steels, is studied. To this end irradiation with iron ions is used in order to simulate the neutron-induced damage. Due to the limited penetration depth characterization methods suitable for thin layers have to be applied. In the present case, nanohardness testing and transmission electron microscopy (TEM) are employed. The results, including the irradiation-induced hardness change of the layer as a function of chromium content, fluence and irradiation temperature and, for selected cases, quantitative TEM analyses, were exploited to identify irradiation-induced dislocation loops as one source of irradiation hardening. Additional results of small-angle neutron scattering experiments on neutron-irradiated specimens of the same alloys show that nm-scaled α'-phase precipitates also significantly contribute to the irradiation-induced hardness increase. An Orowan model is used to estimate the obstacle strengths posed to dislocation glide by these lattice defects. The topic is stepwise extended to more complex situations with respect to the irradiation conditions and the materials. Considering simultaneous and sequential irradiations with iron- and helium-ions it is shown that the effect of helium on irradiation hardening depends on the chronological order of the irradiations and that the simultaneous introduction of helium in fusion-relevant concentrations amplifies irradiation hardening based on a synergistic effect. There is no

Synthesis and sonocatalytic performance of a ternary magnetic MIL-101(Cr)/RGO/ZnFe2O4 nanocomposite for degradation of dye pollutants.

Science.gov (United States)

Nirumand, Ladan; Farhadi, Saeed; Zabardasti, Abedin; Khataee, Alireza

2018-04-01

In this study, new ternary magnetic MIL-101(Cr)/RGO/ZnFe 2 O 4 catalyst (with 30% wt of ZnFe 2 O 4 ) was synthesized via a hydrothermal route for sonodegradation of organic dyes. The structural, optical and magnetic properties of the nanocomposite were detected by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-visible), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, vibrating sample magnetometer (VSM), atomic force microscopy (AFM), Raman spectroscopy and BET surface area analysis. To evaluate the sonocatalytic activity of the as-prepared MIL-101(Cr)/RGO/ZnFe 2 O 4 nanocomposite, the H 2 O 2 -assisted degradation of organic dyes such as congo red (CR), methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) in aqueous solution was studied under ultrasound irradiation. The obtained results indicated that the ternary MIL-101(Cr)/RGO/ZnFe 2 O 4 nanocomposite had better performance for sonodegradation of these dyes than MIL-101(Cr)/RGO, pure MIL-101(Cr) or ZnFe 2 O 4 . The enhanced sonocatalytic performance of the as-prepared ternary nanocomposite could be attributed to the fast generation and separation of charge carriers (electrons and holes) in ZnFe 2 O 4 and MIL-101(Cr) and their transfer to the surface of graphene sheets. Moreover, the relatively high specific surface area of the MIL-101(Cr)/rGO and magnetic property of ZnFe 2 O 4 improve the degradation efficiency of the dyes. The recovery of the ternary magnetic sonocatalyst from treated water could be easily achieved using an external magnetic field. The main influence factors on the sonocatalytic activity such as catalyst dosage and dye initial concentration were also investigated. The trapping experiments indicated that OH radicals are the prominent active species in dye degradation. In addition, the reusability test, was also carried out to ensure the stability of the employed sonocatalyst

Site occupancy and magnetic study of Al3+ and Cr3+ co-substituted Y3Fe5O12

International Nuclear Information System (INIS)

Bouziane, K.; Yousif, A.; Widatallah, H.M.; Amighian, J.

2008-01-01

Single-phased polycrystalline Y 3 Fe 5-2x Al x Cr x O 12 garnet samples (x=0, 0.2, 0.4 and 0.6) have been prepared by the conventional ceramic technique. Rietveld refinement of X-ray diffraction patterns of the samples shows them to crystallize in the Ia3d space group and the corresponding lattice constant to decrease with increasing Al 3+ and Cr 3+ contents (x). Moessbauer results indicate that Cr 3+ substitutes for Fe 3+ at the octahedral sites whilst Al 3+ essentially replaces Fe 3+ at the tetrahedral sites. This result indicates that co-doping of Y 3 Fe 5 O 12 does not affect the preferential site occupancy for separate individual substitution of either Cr 3+ or Al 3+ . The magnetization measurements reveal that the Curie temperature (T c ) monotonically decreases with increasing x while the magnetic moment per unit formula decreases up to x=0.4 and then slightly increases for x=0.6. This reflects a progressive weakening of the ferrimagnetic exchange interaction between the Fe 3+ ions at octahedral and tetrahedral sites due to co-substitution. The magnetic moment was calculated using the cations distribution inferred from the Moessbauer data and the collinear ferrimagnetic model, and was found to agree reasonably with the experimentally measured value. The phenomenological amplitude crossover, characterized by the temperature T*, has also been observed in the doped YIG and briefly discussed

Batch adsorption of heavy metals (Cu, Pb, Fe, Cr and Cd) from ...

African Journals Online (AJOL)

cinthia

This study was carried out to evaluate the efficiency of metals (Cu, Fe, Pb, Cr and Cd) removal from mixed metal ions solution using coconut husk as adsorbent. The effects of varying contact time, initial metal ion concentration, adsorbent dose and pH on adsorption process of these metals were studied using synthetically ...

Cr-tolerance of the IT-SOFC La(Ni,Fe)O3 material

NARCIS (Netherlands)

Stodolny, M.K.

2012-01-01

This thesis deals with a study on the Cr-tolerance of the LaNi0.6Fe0.4O3 (LNF) material. LNF is being considered for use as a current collecting layer, an interconnect protective coating and/or an electrochemically active solid oxide fuel cell (SOFC) cathode layer in an intermediate temperature

Reversal magnetization dependence with the Cr and Fe oxidation states in YFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) perovskites

Energy Technology Data Exchange (ETDEWEB)

Fabian, F.A., E-mail: fernandafabianro@gmail.com [Universidade Federal de Sergipe, Campus Prof. Aloísio Campos, Departamento de Física, 49100−000 São Cristóvão, SE (Brazil); Pedra, P.P. [Universidade Federal de Sergipe, Campus Prof. Aloísio Campos, Departamento de Física, 49100−000 São Cristóvão, SE (Brazil); Moura, K.O. [Universidade Estadual de Campinas, Instituto de Física “Gleb Wataghin”, 13083−859 Campinas, SP (Brazil); Duque, J.G.S.; Meneses, C.T. [Universidade Federal de Sergipe, Campus Prof. Alberto Carvalho, Departamento de Física, 49500−000 Itabaiana, SE (Brazil)

2016-06-15

In this work, we have carried out a detailed study of the magnetic and structural properties of YFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) samples with orthorhombic structure obtained by co-precipitation method. Analysis of X-ray diffraction data using Rietveld refinement show that all samples present an orthorhombic crystal system with space group Pnma. Besides, we have observed a reduction of unit cell volume with increasing of the Cr concentration. SEM images show the formation of grains of micrometer order. X-ray Absorption near edge spectroscopy (XANES) measurements show a shift of absorption edge which can be indicate there is (i) different oxidation states to Fe and Cr ions and/or (ii) a changing in the point symmetry of Fe and Cr ions to the compounds. The magnetization measurements indicate a continuous decreasing of the magnetic transition temperature as function of chromium doping. The reversal magnetization effect was observed to concentrations around x=0.5. Besides, the deviation of the Curie–Weiss law and a weak ferromagnetic behavior observed at room temperature in the M vs H curves can be attributed to the strong magnetic interactions between the transition metals with different oxidation states. - Highlights: • YFe{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤1) samples were synthesized by co-precipitation method. • XRD dates showed a reduction of unit cell volume with addition of Cr. • XANES dates showed difference in the oxidation states to Cr and Fe. • MZFC-MFC indicate a decreasing of the T{sub N} as function of chromium doping. • MFC curve for x=0.5 concentration was observed the reverse magnetization effect.

Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions

International Nuclear Information System (INIS)

Kurepin, V. A.; Kulik, D. A.; Hitpold, A.; Nicolet, M.

2002-03-01

In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO 2 by incremental additions of O 2 in H 2 O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni phase, maintaining

Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions

Energy Technology Data Exchange (ETDEWEB)

Kurepin, V.A.; Kulik, D.A.; Hitpold, A.; Nicolet, M

2002-03-01

In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO{sub 2} by incremental additions of O{sub 2} in H{sub 2}O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni

Development of a Real-Time Smoke Belching Monitoring System for Public Utility Vehicles (PUV via GSM

Directory of Open Access Journals (Sweden)

Nelson C. Rodelas

2016-05-01

Full Text Available The Development of a Real-Time-Based Smoke Belching Monitoring System for Public Utility Vehicle is designed in order to monitor smoke belchers or violators among public utility vehicles (PUV that uses diesel such as jeepneys or buses. The concept of the project is to measure the opacity of the smoke being emitted by the PUV with the use of a predesigned sensor unit incorporated by Light Dependent Resistor Sensor and Light Source facing each other, 4 inches apart. By allowing the smoke to pass through the LDR and Light Source, the desired resistance is acquired and processed by the microcontroller to obtain the Light Absorption Coefficient. This value is the basis for being a smoke belcher (If it exceeds 2.5 k. The system then sends the data (Plate Number and K -value for every one (1 hour to the Database System and to the operator with the aid of GSM Microcontroller that leads to a real time monitoring. The system is possible to implement and has a potential to be used for emission testing centers since it has the features of the commercial opacity meter which is common in emission centers to measure the smoke emitted by the diesel-fueled vehicles. This project serves as an innovation in emission testing because it monitors the smoke belchers in real-time and operators or owners of the vehicle are not required anymore to go to the emission testing center every year to renew their car registration.

First-principles investigation of diffusion and defect properties of Fe and Ni in Cr2O3

Science.gov (United States)

Rak, Zs.; Brenner, D. W.

2018-04-01

Diffusion of Fe and Ni and the energetics of Fe- and Ni-related defects in chromium oxide (α-Cr2O3) are investigated using first-principles Density Functional Theory calculations in combination with the climbing-image nudged elastic band method. The orientations of the spin magnetic moments of the migrating ions are taken into account and their effects on migration barriers are examined. Several possible diffusion pathways were explored through interstitial and vacancy mechanisms, and it was found that the principal mode of ion transport in Cr2O3 is via vacancies. Both interstitial- and vacancy-mediated diffusions are anisotropic, with diffusion being faster in the z-direction. The energetics of defect formation indicates that the Ni-related defects are less stable than the Fe-related ones. This is consistent with Ni-diffusion being faster than Fe-diffusion. The results are compared with previous theoretical and experimental data and possible implications in corrosion control are discussed.

Microstructure and Mechanical Properties of Highly Alloyed FeCrMoVC Steel Fabricated by Spark Plasma Sintering

Science.gov (United States)

Oh, Seung-Jin; Jun, Joong-Hwan; Lee, Min-Ha; Shon, In-Jin; Lee, Seok-Jae

2018-05-01

In this study, we successfully fabricated highly alloyed FeCrMoVC specimens within 2 min by using the spark plasma sintering (SPS) method. The densities of the sintered specimens were almost identical to their theoretical values. Fine (Mo, V)-rich carbides with lamellar structure were precipitated along the grain boundaries of the as-sintered specimen, whereas relatively large carbides were formed additionally in the transgranular region during the tempering treatment. Compared with the specimen produced by a conventional casting method, the FeCrMoVC specimens from SPS showed smaller grain size with finer carbides and higher hardness values.

Modelling phase separation in Fe-Cr system using different atomistic kinetic Monte Carlo techniques

International Nuclear Information System (INIS)

Castin, N.; Bonny, G.; Terentyev, D.; Lavrentiev, M.Yu.; Nguyen-Manh, D.

2011-01-01

Atomistic kinetic Monte Carlo (AKMC) simulations were performed to study α-α' phase separation in Fe-Cr alloys. Two different energy models and two approaches to estimate the local vacancy migration barriers were used. The energy models considered are a two-band model Fe-Cr potential and a cluster expansion, both fitted to ab initio data. The classical Kang-Weinberg decomposition, based on the total energy change of the system, and an Artificial Neural Network (ANN), employed as a regression tool were used to predict the local vacancy migration barriers 'on the fly'. The results are compared with experimental thermal annealing data and differences between the applied AKMC approaches are discussed. The ability of the ANN regression method to accurately predict migration barriers not present in the training list is also addressed by performing cross-check calculations using the nudged elastic band method.

At last! The single-crystal X-ray structure of a naturally occurring sample of the ilmenite-type oxide FeCrO3.

Science.gov (United States)

Pérez-Cruz, María Ana; Elizalde-González, María de la Paz; Escudero, Roberto; Bernès, Sylvain; Silva-González, Rutilo; Reyes-Ortega, Yasmi

2015-10-01

A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R3̅. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3 (hematite) and Cr2O3 (eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3 [Sadat Nabi & Pentcheva (2011). Phys. Rev. B, 83, 214424], and suggest that synthetic samples of FeCrO3 might present a cation distribution different to that of the ilmenite structural type.

Effect of Perovskite coating on oxide scale growth on Fe-22Cr

DEFF Research Database (Denmark)

Persson, Åsa; Mikkelsen, Lars; Hendriksen, Peter Vang

2006-01-01

A coating consisting of La0.85Sr0.15MnO3 (LSM) was deposited onto two Fe 22 wt % Cr alloys Crofer 22APU and Sandvik lC44Mo20. The evolution of the oxide layers developing underneath the coatings during oxidation was investigated. The effect of the LSM coating on oxidation rate and microstructure ...

Hydrogen storage in TiCr1.2(FeV)x BCC solid solutions

International Nuclear Information System (INIS)

Santos, Sydney F.; Huot, Jacques

2009-01-01

The Ti-V-based BCC solid solutions have been considered attractive candidates for hydrogen storage due to their relatively large hydrogen absorbing capacities near room temperature. In spite of this, improvements of some issues should be achieved to allow the technological applications of these alloys. Higher reversible hydrogen storage capacity, decreasing the hysteresis of PCI curves, and decrease in the cost of the raw materials are needed. In the case of vanadium-rich BCC solid solutions, which usually have large hydrogen storage capacities, the search for raw materials with lower cost is mandatory since pure vanadium is quite expensive. Recently, the substitutions of vanadium in these alloys have been tried and some interesting results were achieved by replacing vanadium by commercial ferrovanadium (FeV) alloy. In the present work, this approach was also adopted and TiCr 1.2 (FeV) x alloy series was investigated. The XRD patterns showed the co-existence of a BCC solid solution and a C14 Laves phase in these alloys. SEM analysis showed the alloys consisted of dendritic microstructure and C14 colonies. The amount of C14 phase increases when the amount of (FeV) decreases in these alloys. Concerning the hydrogen storage, the best results were obtained for the TiCr 1.2 (FeV) 0.4 alloy, which achieved 2.79 mass% of hydrogen storage capacity and 1.36 mass% of reversible hydrogen storage capacity

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of Cr, Fe, Cu, Zn and Se in cereals

Science.gov (United States)

Huang, Shih-Yi; Jiang, Shiuh-Jen; Sahayam, A. C.

2014-11-01

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Fe, Cu, Zn and Se in several cereal samples. Thioacetamide was used as the modifier to enhance the ion signals. The background ions at the masses of interest were reduced in intensity significantly by using 1.0 mL min- 1 methane (CH4) as reaction cell gas in the dynamic reaction cell (DRC). Since the sensitivities of Cr, Fe, Cu, Zn and Se in different matrices were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Fe, Cu, Zn and Se in these cereal samples. The method detection limits estimated from standard addition curves were about 1, 10, 4, 12 and 2 ng g- 1 for Cr, Fe, Cu, Zn and Se, respectively, in original cereal samples. This procedure has been applied to the determination of Cr, Fe, Cu, Zn and Se whose concentrations are in μg g- 1 (except Cr and Se) in standard reference materials (SRM) of National institute of standards and technology (NIST), NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and two cereal samples purchased from a local market. The analysis results of reference materials agreed with certified values at 95% confidence level according to Student's T-test. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization DRC ICP-MS results of the sample solutions.

Status Report on Irradiation Capsules Designed to Evaluate FeCrAl-UO₂ Interactions