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Sample records for fe-nb-hf-y-b bulk glassy

  1. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

    2000-01-01

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  2. Formation and Applications of Bulk Glassy Alloys in Late Transition Metal Base System

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Shen Baolong

    2006-01-01

    This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM base BGAs are promising as new metallic engineering materials

  3. FeNbB bulk metallic glass with high boron content

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, M.; Das, Jayanta; Eckert, Juergen [IFW Dresden, Institute for Complex Materials, P.O. Box 270016, D-01171 Dresden (Germany); Hajlaoui, Khalil; Yavari, Alain Reza [LTPCM-CNRS, I.N.P. Grenoble, 1130 Rue de la Piscine, BP 75, F-38402 University Campus (France)

    2007-07-01

    Fe-based alloys able to form magnetic bulk metallic glasses (BMGs) are of the type transition metal - metalloid and often contain 5 or more elements. Usually, the metalloid content is around 20 atomic %. Very recently, the Fe{sub 66}Nb{sub 4}B{sub 30} alloy was found to be able to form BMG by copper mold casting technique, despite its high metalloid content. Several composition with boron contents around 30 at. % or even higher were calculated since 1993 as possible compositions of the remaining amorphous matrix after the first stage of nanocrystallization of Finemet-type Fe{sub 77}Si{sub 14}B{sub 9} glassy ribbons with 0.5 to 1 atomic % Cu and a few percent Nb addition. Melt-spun ribbons of all calculated compositions were found to be glassy. The composition of the ternary Fe-based BMG investigated in the present study resulted as an optimization of all possibilities. The alloy is ferromagnetic with glass transition temperature T{sub g}=845 K, crystallisation temperature T{sub x}=876 K, liquidus temperature T{sub liq}=1451 K and mechanical strength of 4 GPa. The coercivity of as-cast samples is very low, around 1.5 A/m. The present contribution aims at discussing the thermal stability, mechanical and magnetic properties of the Fe{sub 66}Nb{sub 4}B{sub 30} BMG.

  4. Magneto-thermo-gravimetric technique to investigate the structural and magnetic properties of Fe-B-Nb-Y Bulk Metallic Glass

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangmin; Makino, Akihiro; Inoue, Akihisa [Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Masood, Ansar; Tamaki, Takahiko; Valter, Strom; Rao, K V, E-mail: smlee@imr.tohoku.ac.j [Royal Institute of Technology (KTH), SE-100 44 Stockhom (Sweden)

    2009-01-01

    Magneto-thermo-gravimetric (MTG) technique is highly informative about the changes in the magnetic state, as well as structural changes in a system, which cannot be often noticed in calorimetric measurements. We demonstrate the versatility of this technique in determining the magnetic transition temperature, and the subsequent crystallization process in a (Fe{sub 0.72}B{sub 0.24}Nb{sub 0.04}){sub 95.5}Y{sub 4.5} Bulk Metallic Glass (BMG). MTG and DSC analyses were carried out at the heating rate of 0.67 K/s from RT {approx}1170 K. As a result of the repeated MTG measurements, a magnetic 2nd amorphous phase was observed in the BMG sample, which could be the first measurement for the Magnetic Short Range Ordering (MSRO). Consequently, the MTG measurement is proved as the most convenient method for determining the various structural and magnetic transitions in a glassy material.

  5. 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

  6. 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.

  7. Cluster-based bulk metallic glass formation in Fe-Si-B-Nb alloy systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, C L; Wang, Q; Li, F W; Li, Y H; Wang, Y M; Dong, C [State Key Laboratory of Materials Modification, Dalian University of Technology (DUT), Dalian 116024 (China); Zhang, W; Inoue, A, E-mail: dong@dlut.edu.c [Institute for Materials Research (IMR), Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

    2009-01-01

    Bulk metallic glass formations have been explored in Fe-B-Si-Nb alloy system using the so-called atomic cluster line approach in combination with minor alloying guideline. The atomic cluster line refers to a straight line linking binary cluster to the third element in a ternary system. The basic ternary compositions in Fe-B-Si system are determined by the inetersection points of two cluster lines, namely Fe-B cluster to Si and Fe-Si cluster to B, and then further alloyed with 3-5 at. % Nb for enhancing glass forming abilities. BMG rods with a diameter of 3 mm are formed under the case of minor Nb alloying the basic intersecting compositions of Fe{sub 8}B{sub 3}-Si with Fe{sub 12}Si-B and Fe{sub 8}B{sub 2}-Si with Fe{sub 9}Si-B. The BMGs also exhibit high Vickers hardness (H{sub v}) of 1130-1164 and high Young's modulous (E) of 170-180 GPa

  8. High coercivity in Fe-Nb-B-Dy bulk nanocrystalline magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ziolkowski, Grzegorz; Chrobak, Artur; Klimontko, Joanna [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007, Katowice (Poland); Chrobak, Dariusz; Rak, Jan [Institute of Materials Science, University of Silesia, 75 Pulku Piechoty 1, 41-500, Chorzow (Poland); Zivotsky, Ondrej; Hendrych, Ales [Department of Physics, VSB-TU Ostrava, Ostrava (Czech Republic)

    2016-11-15

    The paper refers to structural and magnetic properties of the (Fe{sub 80}Nb{sub 6}B{sub 14}){sub 1-x}Dy{sub x} (x = 0.08, 0.10, 0.12, 0.16) bulk nanocrystalline alloys prepared by making use of the vacuum suction casting technique. The samples are in a form of rods with different diameters d = 1.5, 1, and 0.5 mm. The phase structure was investigated by XRD technique and reveals an occurrence of magnetically hard Dy{sub 2}Fe{sub 14}B as well as other relatively soft Dy-Fe, Fe-B, and Fe phases dependently on the Dy content. The alloys show hard magnetic properties with high coercive field up to 5.5 T (for x = 0.12 and d = 0.5 mm). The observed magnetic hardening effect with the increase of cooling rate (decrease of sample diameter d) can be attributed to a formation of ultra-hard magnetic objects as well as increasing role of low dimensional microstructure. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Study of microstructure and correlative magnetic property in bulk Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Man, H.; Xu, H. [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Liu, H.W. [The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Tan, X.H., E-mail: tanxiaohua123@163.com [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Peng, J.C.; Bai, Q. [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer A fully dense bulk Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} permanent magnet was obtained by the simple process of copper mold casting and subsequent annealed at 943 K. Black-Right-Pointing-Pointer The relationship between microstructures and correlative magnetic property of Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} alloy was investigated. Black-Right-Pointing-Pointer The high value of intrinsic coercivity of 1191 kA/m was obtained due to the existence of hard magnetic Nd{sub 2}Fe{sub 14}B phase. - Abstract: The correlation between microstructure and magnetic property of a bulk Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} alloy are investigated. The microstructure of the as-cast Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} alloy shows a small amount of NbFeB phase with a grain size of 500 nm embedded in an amorphous matrix. The as-cast sample shows soft magnetic behavior at room temperature, after a heat treatment the hard magnetic properties are observed. A fully dense bulk Fe{sub 61}Nd{sub 10}B{sub 25}Nb{sub 4} permanent magnet is obtained with an intrinsic coercivity ({sub i}H{sub c}) of 1191 kA/m and a maximum energy product ((BH){sub max}) of 31.7 kJ/m{sup 3} after annealing at 943 K for 20 min. The corresponding microstructure consists of Nd{sub 2}Fe{sub 14}B, NdFe{sub 4}B{sub 4} and NbFeB phases. The existence of the hard magnetic Nd{sub 2}Fe{sub 14}B phase is the reason resulting in a high value of {sub i}H{sub c}. On the other hand, the influences of NdFe{sub 4}B{sub 4} and NbFeB phases in the annealed specimen on the magnetic properties are also discussed.

  10. Electrical resistivity in Zr48Nb8Cu12Fe8Be24 glassy and crystallized alloys

    Science.gov (United States)

    Bai, H. Y.; Tong, C. Z.; Zheng, P.

    2004-02-01

    The electrical resistivity of Zr48Nb8Cu12Fe8Be24 bulk metallic glassy and crystallized alloys in the temperature range of 4.2-293 K is investigated. It is found that the resistivity in glassy and crystallized states shows opposite temperature coefficients. For the metallic glass, the resistivity shows a negative logarithmic dependence at temperatures below 16 K, whereas it has more normal behavior for the crystallized alloy. At higher temperatures, the resistivity in both glassy and crystallized alloys shows dependence upon both T and T2, but the signs of the T and T2 terms are opposite. The results are interpreted in terms of scattering from two-level tunneling states in glasses and the generalized Ziman diffraction model.

  11. Roles of Co element in Fe-based bulk metallic glasses utilizing industrial FeB alloy as raw material

    Directory of Open Access Journals (Sweden)

    Shouyuan Wang

    2017-08-01

    Full Text Available A series of Fe-based bulk metallic glasses were fabricated by a conventional copper mold casting method using a kind of Fe-B industrial raw alloy. It is found that Fe-B-Y-Nb bulk metallic glass with 3 at% of Co addition possesses the best glass forming ability, thermal stability, hardness, magnetic property and anti-corrosion property. The hardness test result indicates a synchronically trend with glass-forming ability parameters. The excellent glass-forming ability and a combination of good mechanical and functional properties suggest that the alloys in this work might be good candidates for commercial use.

  12. Crystallisation kinetics of amorphous Fe72.5-xCu1Nb4.5Si10+x+yB12-y alloy

    International Nuclear Information System (INIS)

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

    1994-01-01

    Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 and Fe 72.5-x Cu 1 Nb 4.5 Si 10+x+y B 12-y alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 C for x = 0.5, y = 3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder. (orig.)

  13. Effect of niobium on microstructure and magnetic properties of bulk anisotropic NdFeB/{alpha}-Fe nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li Jun [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Liu Ying, E-mail: Liuying5536@163.com [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China) and Key Laboratory of Advanced Special Material and Technology, Ministry of Education, Chengdu 610065 (China); Ma Yilong [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2012-07-15

    Bulk anisotropic NdFeB/{alpha}-Fe nano-composites were obtained directly from alloys of Nd{sub 11}Dy{sub 0.5}Fe{sub 82.4-x}Nb{sub x}B{sub 6.1} (x=0,0.5,1.0,1.5). High resolution transmission electron microscopy images showed the existence of Nb-rich amorphous grain boundary phase in the alloys with Nb doped. Field emission scanning electron microscope morphologies and X-ray diffraction patterns revealed the grain size and grain alignment of hot pressed and hot deformed nanocomposites. It was found that Nb could refine the grain size and grain texture in hot worked ribbons. Vibrating sample magnetometer results showed that the magnetic properties of the anisotropic nanocomposites were improved with increased Nb doping. The remanence, coercivity and maximum energy product of the bulk anisotropic Nd{sub 11}Dy{sub 0.5}Fe{sub 80.4}Nb{sub 2}B{sub 6.1} nanocomposites were 1.04 T, 563 kA/m and 146 kJ/m{sup 3}, respectively. - Highlights: Black-Right-Pointing-Pointer Nb has great influence on the microstructure and magnetic properties of (NdDy){sub 11.5}Fe{sub 82.4-x}Nb{sub x}B{sub 6.1} (x=0-2.0) nanocomposites. Black-Right-Pointing-Pointer Most of Nb atoms gather in the grain boundary to form Nb-rich amorphous intergranular phase, not NbFeB boride. Black-Right-Pointing-Pointer Furthermore, grain alignment can be prompt by the Nb-rich solid intergranular phase during deform. Black-Right-Pointing-Pointer Remanence, coercivity and (BH){sub m} of deformed (NdDy){sub 11.5}Fe{sub 80.4}Nb{sub 2}B{sub 6.1} nanocomposite is 1.04T, 563 kA/m and 146 kJ/m{sup 3} respectively. Black-Right-Pointing-Pointer This study provides an alternative method for prepare anisotropic nanocomposite direct from Nd-lean alloys with low cost.

  14. Photorefractive features of non-stoichiometry codoped Hf:Fe:LiNbO3 single crystals

    International Nuclear Information System (INIS)

    Liu, Bo; Li, Chunliang; Bi, Jiancong; Sun, Liang; Xu, Yuheng

    2008-01-01

    Hf(2mol%):Fe(0.05wt%):LiNbO 3 crystals with various [Li]/[Nb] ratios of 0.94, 1.05, 1.2 and 1.38 have been grown. The photorefractive resistant ability increases with the accretion of [Li]/[Nb] ratio. When the ratio of [Li]/[Nb] is 1.20 or 1.38, the OH - absorption band shifts to about 3477cm -1 . The mechanisms of the photorefractive resistant ability increase and the absorption band shift have been discussed. The exponential gain coefficient (Γ) of the crystals was measured with two-beam coupling method and the effective charge carrier concentration (N eff ) was calculated. The results show that Γ and N eff increase with the accretion of [Li]/[Nb] ratio. The temperature effect of codoped Hf:Fe:LiNbO 3 crystals was also studied, it was found that the exponential gain coefficient increase dramatically at about 55 C, 70 C and 110 C, this is due to the inner electric field which is resulted from structure phase change. (copyright 2007 WILEY -VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Effects of Cu substitution for Fe on the glass-forming ability and soft magnetic properties for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Dou, Lintao; Liu, Haishun; Hou, Long; Xue, Lin; Yang, Weiming; Zhao, Yucheng; Chang, Chuntao

    2014-01-01

    The effects of Cu substitution for Fe on the glass-forming ability (GFA) and soft magnetic properties for Fe 72−x Cu x B 20 Si 4 Nb 4 (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) bulk metallic glasses (BMGs) are investigated. It is found that the investigated BMGs exhibit large GFA as well as excellent soft magnetic properties, and proper substitution of Fe by Cu improves the saturation magnetization, coercive force, and effective permeability without obvious deterioration of the GFA. - Highlights: • Fully glassy rods of Fe 72−x Cu x B 20 Si 4 Nb 4 BMGs were produced above 1 mm in diameter. • Investigated BMGs exhibit large glass-forming ability and excellent soft magnetic properties. • Proper Cu substitution improves magnetic properties without obvious deterioration of glass-forming ability

  16. Crystallisation kinetics of amorphous Fe{sub 72.5-x}Cu{sub 1}Nb{sub 4.5}Si{sub 10+x+y}B{sub 12-y} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, M. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics; Lipka, J. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics; Sitek, J. [Komenskeho Univ., Bratislava (Czechoslovakia). Dept. of Nuclear Physics and Technics

    1994-11-01

    Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} and Fe{sub 72.5-x}Cu{sub 1}Nb{sub 4.5}Si{sub 10+x+y}B{sub 12-y} alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 C for x = 0.5, y = 3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder. (orig.)

  17. Formation of bulk metallic glasses in the Fe-M-Y-B (M = transition metal) system

    Energy Technology Data Exchange (ETDEWEB)

    Huang, X.M. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chang, C.T. [Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Chang, Z.Y.; Wang, X.D.; Cao, Q.P. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Shen, B.L.; Inoue, A. [Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Jiang, J.Z. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)], E-mail: jiangjz@zju.edu.cn

    2008-07-28

    In this work, quaternary Fe{sub 72-x}M{sub x}Y{sub 6}B{sub 22} (M = Ni, Co and Mo) bulk metallic glasses (BMGs) have been developed. It is found that a fully amorphous Fe{sub 68}Mo{sub 4}Y{sub 6}B{sub 22} cylindrical rod with 6.5 mm in diameter can be prepared by copper mold injection. These alloys have a high glass transition temperature of about 900 K with high fracture strengths up to about 3 GPa although they are still brittle. Magnetic measurements reveal that they are ferromagnetic at ambient temperature with low coercive force of about 2 A/m, saturation magnetization of about 0.7 T and effective permeability of about 7000 at 100 kHz. The newly developed Fe-based quaternary alloys exhibit excellent combination properties: superior glass forming ability (GFA), high glass transition temperature, and soft magnetic properties, which could have potential applications in electronic industries. Furthermore, the effect of Mo addition on GFA in the Fe-Y-B BMG system has been discussed compared with those of Ni and Co additions.

  18. Investigation of new type Cu-Hf-Al bulk glassy alloys

    International Nuclear Information System (INIS)

    Nagy, E; Ronto, V; Solyom, J; Roosz, A

    2009-01-01

    In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu 49 Hf 42 Al 9 , Cu 46 Hf 45 Al 9 , Cu 50 Hf 42.5 Al 7.5 and Cu 50 Hf 45 Al 5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

  19. Formation, thermal stability and mechanical properties of bulk glassy alloys with a diameter of 20 mm in Zr-(Ti,Nb)-Al-Ni-Cu system

    International Nuclear Information System (INIS)

    Inoue, A.; Zhang, Q.S.; Zhang, W.; Yubuta, K.; Son, K.S.; Wang, X.M.

    2009-01-01

    Bulk glassy alloy rods with a diameter of 20 mm were produced for Zr 61 Ti 2 Nb 2 Al 7.5 Ni 10 Cu 17.5 and Zr 60 Ti 2 Nb 2 Al 7.5 Ni 10 Cu 18.5 by a tilt casting method. The replacement of Zr by a small amount of Ti and Nb caused a distinct increase in the maximum diameter from 16 mm for Zr 65 Al 7.5 Ni 10 Cu 17.5 to 20 mm, accompanying the decrease in liquidus temperature and the increase in reduced glass transition temperature. The primary precipitation phase from supercooled liquid also shows a distinct change, i.e., from coexistent Zr 2 Cu, Zr 2 Ni and Zr 6 NiAl 2 phases for the 65%Zr alloy to an icosahedral phase for the 61%Zr and 60%Zr alloys. These results allow us to presume that the enhancement of the glass-forming ability is due to an increase in the stability of supercooled liquid against crystallization caused by the development of icosahedral short-range ordered atomic configurations. The 60%Zr specimens taken from the central and near-surface regions in the transverse cross section at the site which is 15 mm away from the bottom surface of the cast glassy rod with a diameter of 20 mm exhibit good mechanical properties under a compressive deformation mode, i.e., Young's modulus of 81 GPa, large elastic strain of 0.02, high yield strength of 1610 MPa and distinct plastic strain of 0.012. Besides, a number of shear bands are observed along the maximum shear stress plane on the peripheral surface near the final fracture site. The finding of producing the large scale Zr-based bulk glassy alloys exhibiting reliable mechanical properties is encouraging for future advancement of bulk glassy alloys as a new type of functional material. (author)

  20. FeNbB bulk metallic glass: the influence of fluxing technique

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, Mihai; Eckert, Juergen [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Kumar, Santosh [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India); Roth, Stefan [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Ram, Shanker [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India); Yavari, Alain Reza [LTPCM-CNRS, Institut National Politechnique de Grenoble, 1130 Rue de la Piscine, BP 75, Saint Martin d' Heres Campus 38402 (France)

    2008-07-01

    Recently, a new Fe-based BMG containing only 3 elements and a very high boron (Fe{sub 66}Nb{sub 4}B{sub 30}) content was synthesized. The preparation of this BMG was done by employing the copper mould casting method and using the fluxing technique. This new BMG is ferromagnetic, with a Curie temperature around 550 K and a saturation magnetization of 105 emu/g. Differential scanning calorimetry (DSC) investigations revealed a reduced glass transition temperature of 0.58 and an extension of the supercooled liquid region of about 31 K, values which indicate a relatively good thermal stability. Fluxed and not-fluxed master alloys were used to cast samples. The present work aims to discuss, for both kinds of samples, the kinetics of the phase formation using the Kissinger analysis and Johnson-Mehl-Avrami plots, correlated with the results obtained from X-ray diffraction (XRD) of samples with different metastable structures. Additionally, the magnetic behaviour of different phase(s) is discussed.

  1. Thermoplastic deformation of ferromagnetic CoFe-based bulk metallic glasses

    Science.gov (United States)

    Wu, Chenguang; Hu, Renchao; Man, Qikui; Chang, Chuntao; Wang, Xinmin

    2017-12-01

    The superplastic deformation behavior of the ferromagnetic Co31Fe31Nb8B30 bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications.

  2. Transport, Magnetic, and Memristive Properties of a Nanogranular (CoFeB) x (LiNbO y )100- x Composite Material

    Science.gov (United States)

    Rylkov, V. V.; Nikolaev, S. N.; Demin, V. A.; Emelyanov, A. V.; Sitnikov, A. V.; Nikiruy, K. E.; Levanov, V. A.; Presnyakov, M. Yu.; Taldenkov, A. N.; Vasiliev, A. L.; Chernoglazov, K. Yu.; Vedeneev, A. S.; Kalinin, Yu. E.; Granovsky, A. B.; Tugushev, V. V.; Bugaev, A. S.

    2018-03-01

    The properties of (CoFeB) x (LiNbO y )100- x nanocomposite films with a ferromagnetic alloy content x = 6-48 at % are comprehensively studied. The films are shown to consist of ensembles of CoFe granules 2-4 nm in size, which are strongly elongated (up to 10-15 nm) in the nanocomposite growth direction and are located in an LiNbO y matrix with a high content of Fe2+ and Co2+ magnetic ions (up to 3 × 1022 cm-3). At T ≤ 25 K, a paramagnetic component of the magnetization of nanocomposites is detected along with a ferromagnetic component, and the contribution of the former component is threefold that of the latter. A hysteresis of the magnetization is observed below the percolation threshold up to x ≈ 33 at %, which indicates the appearance of a superferromagnetic order in the nanocomposites. The temperature dependence of the electrical conductivity of the nanocomposites in the range T ≈ 10-200 K on the metallic side of the metal-insulator transition (44 at % law σ( T) ∝ ln T. This law changes into the law of "1/2" at x ≤ 40 at %. The tunneling anomalous Hall effect is strongly suppressed and the longitudinal conductivity turns out to be lower than in a (CoFeB) x (AlO y )100- x composite material by an order of magnitude. The capacitor structures based on (CoFeB) x (LiNbO y )100- x films exhibit resistive switching effects. They are related to (i) the formation of isolated chains of elongated granules and an anomalously strong decrease in the resistance in fields E > 104 V/cm because of the suppression of Coulomb blockage effects and the generation of oxygen vacancies V O and (ii) the injection (or extraction) of V O vacancies (depending on the sign of voltage) into a strongly oxidized layer in the nanocomposites, which is located near an electrode of the structure and controls its resistance. The number of stable resistive switchings exceeds 105 at a resistance ratio R off/ R on 50.

  3. Effect of Yttrium Addition on Glass-Forming Ability and Magnetic Properties of Fe–Co–B–Si–Nb Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Teruo Bitoh

    2015-06-01

    Full Text Available The glass-forming ability (GFA and the magnetic properties of the [(Fe0.5Co0.50.75B0.20Si0.05]96Nb4−xYx bulk metallic glasses (BMGs have been studied. The partial replacement of Nb by Y improves the thermal stability of the glass against crystallization. The saturation mass magnetization (σs exhibits a maximum around 2 at. % Y, and the value of σs of the alloy with 2 at. % Y is 6.5% larger than that of the Y-free alloy. The coercivity shows a tendency to decrease with increasing Y content. These results indicate that the partial replacement of Nb by Y in the Fe–Co–B–Si–Nb BMGs is useful to simultaneous achievement of high GFA, high σs, and good soft magnetic properties.

  4. Formation and properties of two-phase bulk metallic glasses by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guoqiang, E-mail: xiegq@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Louzguine-Luzgin, D.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, Akihisa [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2011-06-15

    Research highlights: > Two-phase bulk metallic glasses with high strength and good soft magnetic properties as well as satisfying large-size requirements were produced by spark plasma sintering. > Effects of sintering temperature on thermal stability, microstructure, mechanical and magnetic properties were investigated. > Densified samples were obtained by the spark plasma sintering at above 773 K. - Abstract: Using a mixture of the gas-atomized Ni{sub 52.5}Nb{sub 10}Zr{sub 15}Ti{sub 15}Pt{sub 7.5} and Fe{sub 73}Si{sub 7}B{sub 17}Nb{sub 3} glassy alloy powders, we produced the two-phase bulk metallic glass (BMG) with high strength and good soft magnetic properties as well as satisfying large-size requirements by the spark plasma sintering (SPS) process. Two kinds of glassy particulates were homogeneously dispersed each other. With an increase in sintering temperature, density of the produced samples increased, and densified samples were obtained by the SPS process at above 773 K. Good bonding state among the Ni- and Fe-based glassy particulates was achieved.

  5. Preparation and properties of Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ling; Ma, XiuHua [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Li, Qiang, E-mail: qli@xju.edu.cn [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Zhang, Jijun [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Dong, Yaqiang; Chang, Chuntao [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

    2014-09-01

    Highlights: • Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20–50 at.%) BMGs were prepared by fluxing and J-quenching techniques. • The highest GFA is reached at x = 40 and the corresponding critical diameter is up to 2.5 mm. • The present FeNi-based BMGs exhibit very large ε{sub p} and the ε{sub p} of Fe{sub 30}Ni{sub 50}P{sub 14}B{sub 6} BMG is 11.7%. • The present FeNi-based BMGs have much higher corrosion resistance than stainless steel. - Abstract: Bulk Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20, 30, 40, 50 at.%) glassy alloy rods with the diameters of 1.0–2.5 mm were synthesized by combining fluxing technique and J-quenching technique. The glassy alloy rods were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). It is found that the range of supercooled liquid region (ΔT{sub x}) is 27–32 K. The saturation magnetization of Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20, 30, 40, 50 at.%) bulk glassy alloys gradually decreases from 1.13 T to 0.58 T with increasing Ni content from x = 20 to x = 50. More importantly, the present quaternary FeNiPB bulk metallic glasses (BMGs) shows a significant plastic strain, in particular, the plastic strain of Fe{sub 30}Ni{sub 50}P{sub 14}B{sub 6} BMG reaches as high as 11.7%. The corrosion resistance of the present FeNiPB BMGs was studied by weight-loss method, potentiodynamic polarization curves and scanning electron microscopy (SEM). It is shown that the corrosion resistance of the present FeNiPB BMGs in 0.5 M NaCl and 1 M HCl solution increases with Ni content, and further the present FeNiPB BMGs exhibit larger E{sub corr} values and lower I{sub corr} values, i.e. higher corrosion resistances, than that of stainless steel.

  6. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  7. Nanocomposite Nd-Y-Fe-B-Mo bulk magnets prepared by injection casting technique

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Shan [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Ahmad, Zubair [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Pengyue [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Yan, Mi, E-mail: mse_yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zheng, Xiaomei [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

    2017-09-01

    Highlights: • Nanocomposite Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets were synthesized by injection casting. • High coercivity of 1289 kA/m was obtained for the directly casted magnet. • Magnetic properties arise from magnetically exchange coupled soft and hard phases. - Abstract: The phase composition, magnetic and microstructural properties of Nd{sub 2}Fe{sub 14}B/(α-Fe, Fe{sub 3}B) nanocomposite magnets produced by injection casting technique have been studied. Magnetic hysteresis loop of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} permanent magnet demonstrates the coercivity as high as 1289 kA/m. Electron microscopy elucidates a microstructure composed of magnetically soft α-Fe, Fe{sub 3}B and hard Nd{sub 2}Fe{sub 14}B/Y{sub 2}Fe{sub 14}B nanograins (20–50 nm) separated by ultra-thin grain boundary layer. The Henkel plot curve of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} magnet yields the existence of exchange coupling interactions between soft and hard phases. Macroscopically large size sheet magnet is obtained due to high glass forming ability of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} alloy derived from large atomic radius mismatch and negative enthalpy of alloy constituent elements. The high coercivity of the magnet is attributed to the magnetically hard phase increment, nucleation of reverse domains and the presence of thin grain boundary phase. Good magnetic properties such as remanence of 0.51 T, coercivity of 1289 kA/m and maximum energy product of 46.2 kJ/m{sup 3} are obtained in directly casted Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets.

  8. Thermal treatment induced modification of structural, surface and bulk magnetic properties of Fe61.5Co5Ni8Si13.5B9Nb3 metallic glass

    Science.gov (United States)

    Shah, M.; Satalkar, M.; Kane, S. N.; Ghodke, N. L.; Sinha, A. K.; Varga, L. K.; Teixeira, J. M.; Araujo, J. P.

    2018-05-01

    Effect of thermal annealing induced modification of structural, surface and bulk magnetic properties of Fe61.5Co5Ni8Si13.5B9Nb3 alloy is presented. The changes in properties were observed using synchrotron x-ray diffraction technique (SXRD), atomic force microscopy (AFM), magneto-optical kerr effect (MOKE) and bulk magnetic measurements. Significant variations on the both side of surface occur for the annealing temperature upto 500 °C promotes the surface crystallization. Surface roughness appears due to presence of nanocrystallization plays an important role in determining magnetic properties. Observed lower value of bulk coercivity Hc of 6.2 A/m annealed temperature at 450 °C/1 h ascribed to reduction of disorder as compared to the surface (both shiny and wheel side observed by MOKE measurement) whereas improvement of bulk saturation magnetization with annealing temperature indicates first near neighbor shell of Fe atoms are surrounded by Fe atoms. Evolution of coercivity of surface and bulk with annealing temperature has been presented in conjunction with the structural observations.

  9. Structure and soft magnetic properties of the bulk samples prepared by compaction of the mixtures of Co-based and Fe-based powders

    International Nuclear Information System (INIS)

    Fuezer, J.; Bednarcik, J.; Kollar, P.; Roth, S.

    2007-01-01

    Ball milling of CoFeZrB ribbons and subsequent compaction of the resulting powders were used to prepare bulk amorphous samples. Further, two sets of powder samples were prepared by cryomilling of FeCuNbMoSiB alloy in amorphous and nanocrystalline state. Amorphous and nanocrystalline FeCuNbMoSiB powders were blended with CoFeZrB powder at different concentrations. Such powder mixtures were consolidated and several bulk nanocomposites have been synthesized. An addition of nanocrystalline or amorphous FeCuNbMoSiB powder to amorphous CoFeZrB powder caused a decrease of the magnetostriction of the resultant bulk samples, while the coercivity shows an opposite behavior. Our results show that the powder consolidation by hot pressing is an alternative method for the preparation of bulk metallic glasses, which are difficult to prepare by casting methods

  10. Effects of Nb and Si on densities of valence electrons in bulk and defects of Fe3Al alloys

    Institute of Scientific and Technical Information of China (English)

    邓文; 钟夏平; 黄宇阳; 熊良钺; 王淑荷; 郭建亭; 龙期威

    1999-01-01

    Positron lifetime measurements have been performed in binary Fe3Al and Fe3Al doping with Nb or Si alloys. The densities of valence electrons of the bulk and microdefects in all tested samples have been calculated by using the positron lifetime parameters. Density of valence electron is low in the bulk of Fe3Al alloy. It indicates that, the 3d electrons in a Fe atom have strong-localized properties and tend to form covalent bonds with Al atoms, and the bonding nature in Fe3Al is a mixture of metallic and covalent bonds. The density of valence electron is very low in the defects of Fe3Al grain boundary, which makes the bonding cohesion in grain boundary quite weak. The addition of Si to Fe3Al gives rise to the decrease of the densities of valence electrons in the bulk and the grain boundary thus the metallic bonding cohesion. This makes the alloy more brittle. The addition of Nb to Fe3Al results in the decrease of the ordering energy of the alloy and increases the density of valence electron and th

  11. Spacer layer effect and microstructure on multi-layer [NdFeB/Nb]n films

    International Nuclear Information System (INIS)

    Tsai, J.-L.; Yao, Y.-D.; Chin, T.-S.; Kronmueller, H.

    2002-01-01

    Spacer layer effect on multi-layer [NdFeB/Nb] n films has been investigated from the variation of magnetic properties and microstructure of the films. From a HRTEM cross-section view observation, the average grain size of [NdFeB/Nb] n multi-layers was controlled by both annealing temperature and thickness of NdFeB layer. Selected area diffraction pattern indicated that the structure of Nb spacer layer was amorphous. The grain size and coercivity of [NdFeB x /Nb] n films change from 50 nm and 16.7 kOe to 167 nm and 9 kOe for films with x=40 nm, n=10 and x=200 nm, n=2, respectively

  12. Beta decomposition processes in Hf-rich Hf--Nb alloys

    International Nuclear Information System (INIS)

    Jones, W.B.; Taggart, R.; Polonis, D.H.

    1978-01-01

    The decomposition of the bcc β-phase by both athermal and isothermal processes has been investigated in Hf-rich Hf--Nb alloys. An all β-phase structure is retained in chill-cast alloys containing 30 to 50 at.% Nb (Cb), although electron diffraction streaking effects and the behavior of the temperature coefficient of electrical resistivity indicate the presence of a bcc lattice instability similar to that reported in solute lean Ti and Zr alloys. Aging a Hf 0 . 65 Nb 0 . 35 alloy at 400 and 600 0 C resulted in the direct precipitation of a fine dispersion of α-phase needles; this morphology differs from the discs of transition α (α/sub t/) which Carpenter et al observed in Nb-rich Nb 0 . 68 Hf 0 . 32 . During continued aging, the needles grow selectively to form colonies or groups of needles in which both the individual needles and the groups of needles have major axes aligned along (110)/sub β/ type directions. The initial α-phase particles exhibit the Burgers orientation relationship with the parent matrix; continued aging changes the electron diffraction patterns in a way that is similar to that observed in aged Ti--Mo and Ti--Mo--Al alloys where they were attributed to the α-phase having a different crystallographic relationship to the β-phase (Type 2 α-phase). The observed changes in the electron diffraction patterns of aged Hf 0 . 65 Nb 0 . 35 cannot be described as resulting from strained Burgers α-phase

  13. Preparation and properties of [(NdFeB)x/(Nb)z]n multi-layer films

    International Nuclear Information System (INIS)

    Tsai, J.-L.; Chin, T.-S.; Yao, Y.-D.; Melsheimer, A.; Fisher, S.; Drogen, T.; Kelsch, M.; Kronmueller, H.

    2003-01-01

    Multi-layer [(NdFeB) x /(Nb) z ] n films with 200 nm≥x≥10 nm, 10 nm≥z≥0, 40≥n≥2, prepared by ion beam sputtering and subsequent annealing, show significantly enhanced coercivity due to the reduced grain size that enhances the anisotropy of individual grains. After annealing at 630 deg. C, some Nd 2 Fe 14 B grains were enriched with Nb and isolated as the thickness of the Nb spacer layer increases. For multi-layer (NdFeB x /Nb z ) n films with 100 nm ≥x≥25 nm, 5 nm≥z≥2 nm, their coercivity and remanence ratio are better than that of a single NdFeB film. Up to 17.8 kOe room temperature coercivity has been obtained for a sample with x=25 nm, z=5 nm and n=16

  14. Moessbauer study of isothermally annealed amorphous Fe-Nb-Cu-Si-B alloys

    International Nuclear Information System (INIS)

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

    1993-01-01

    Amorphous ribbons of Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 have been annealed above the crystallization temperature. Annealed samples consisted of crystalline and amorphous phases in a wide temperature range. Two samples of different thicknesses of 33 μm and 27 μm were isothermally annealed at a temperature of 545 C from 0.5 to 5 h in a vacuum furnace. The amount of crystalline phase increases rapidly in the ticker sample. The crystalline part of the Moessbauer spectrum consists of four sharp sextets which can be assigned to a DO 3 -structure FeSi alloy. After 700 C annealing the amorphous phase was not observed and the crystalline phase consisted of the DO 3 -structure FeSi alloy, paramagnetic FeNbB and presumably Fe 23 B 6 and Fe 3 SiB 2 . (orig.)

  15. The Magnetization Reversal Processes Of Bulk (Nd, Y-(Fe, Co-B Alloy In The As-Quenched State

    Directory of Open Access Journals (Sweden)

    Dośpiał M.

    2015-09-01

    Full Text Available The magnetization reversal processes of bulk Fe64Co5Nd6Y6B19 alloy in the as-quenched state have been investigated. From the analysis of the initial magnetization curve and differential susceptibility versus an internal magnetic field it was deduced, that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain’s boundaries of the Nd2Fe14B phase. Basing on the dependence of the reversible magnetization component as a function of magnetic field it was found that reversible rotation of a magnetic moment vector and motion of domain walls in multi-domain grains result in high initial values of the reversible component. The presence of at least two maxima on differential susceptibility of irreversible magnetization component in function of magnetic field imply existence of few pinning sites of domain walls in Fe64Co5Nd6Y6B19 alloy. The dominant interactions between particles have been determined on the basis of the Wohlfarth dependence. Such a behavior of Wohlfarth’s plot implies that the dominant interaction between grains becomes short range exchange interactions.

  16. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Science.gov (United States)

    Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 1689±85 HV0.01, and 181±7 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  17. The Effects of a High Magnetic Field on the Annealing of [(Fe0.5Co0.50.75B0.2Si0.05]96Nb4 Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Peng Jia

    2016-11-01

    Full Text Available In contrast with amorphous alloys, nanocrystalline soft magnetic materials show improved thermal stability and higher soft magnetic properties. The nanocrystalline soft magnetic composites are usually fabricated by partially crystallizing from parent amorphous alloys. This paper reports our experimental observation on the sequence of crystallization in metallic glass under a high magnetic field (HMF. An application of a HMF to bulk metallic glass (BMG of [(Fe0.5Co0.50.75B0.2Si0.05]96Nb4 prioritizes the precipitation of α-(Fe,Co phase separated from the subsequent precipitation of borides, (Fe,Co23B6, upon isothermal annealing at a glass transition temperature. Furthermore, it was observed that, through the annealing treatment under a HMF, a soft magnetic nanocomposite, in which only α-(Fe,Co phase uniformly distributes in amorphous matrix, was achieved for boron-bearing BMG. The promotion of the α-Fe or (Fe,Co phase and the prevention of the boride phases during the isothermal annealing process help to produce high-quality soft magnetic nanocomposite materials. The mechanism by which a HMF influences the crystallization sequence was interpreted via certain changes in Gibbs free energies for two ferromagnetic phases. This finding evidences that the annealing treatment under a HMF is suitable for enhancing the soft magnetic properties of high B content (Fe,Co-based bulk amorphous and nanocrystalline materials.

  18. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Energy Technology Data Exchange (ETDEWEB)

    Kilinc, B., E-mail: bkilinc@sakarya.edu.tr; Durmaz, M.; Abakay, E. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, SakaryaUniversity, Esentepe Campus, 54187Sakarya (Turkey); Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  19. Core losses of ring-shaped (Fe{sub 0.75}B{sub 0.20}Si{sub 0.05}){sub 96}Nb{sub 4} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Bitoh, T; Ishikawa, T; Okumura, H, E-mail: teruo_bitoh@akita-pu.ac.jp [Department of Machine Intelligence and Systems Engineering, Faculty of Systems Science and Technology, Akita Prefectural University, Yurihonjo, 015-0055 (Japan)

    2011-01-01

    The soft magnetic properties of ring-shaped (Fe{sub 0.75}B{sub 0.20}Si{sub 0.05}){sub 96}Nb{sub 4} cast bulk metallic glass (BMG) with thickness of 0.3-1.0 mm have been investigated. The BMG specimens exhibit high relative permeability of (9-29)x10{sup 3} at 0.40 A/m and 50 Hz and low coercivity of 4.0 A/m. The core losses of the 0.3 mm thick BMG specimen are lower than those of commercial Fe-6.5 mass% Si steel (6.5Si) with the same thickness, and are comparable to those of the 0.10 mm thick 6.5Si. The low core losses of the BMG originate from the low coercivity and high electrical resistivity.

  20. Moessbauer study of isothermally annealed amorphous Fe-Nb-Cu-Si-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, J. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Toth, I. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Miglierini, M. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia))

    1993-11-01

    Amorphous ribbons of Fe[sub 73.5]Nb[sub 3]Cu[sub 1]Si[sub 13.5]B[sub 9] have been annealed above the crystallization temperature. Annealed samples consisted of crystalline and amorphous phases in a wide temperature range. Two samples of different thicknesses of 33 [mu]m and 27 [mu]m were isothermally annealed at a temperature of 545 C from 0.5 to 5 h in a vacuum furnace. The amount of crystalline phase increases rapidly in the ticker sample. The crystalline part of the Moessbauer spectrum consists of four sharp sextets which can be assigned to a DO[sub 3]-structure FeSi alloy. After 700 C annealing the amorphous phase was not observed and the crystalline phase consisted of the DO[sub 3]-structure FeSi alloy, paramagnetic FeNbB and presumably Fe[sub 23]B[sub 6] and Fe[sub 3]SiB[sub 2]. (orig.)

  1. Effect of Nb aggregates on Zr2Fe

    International Nuclear Information System (INIS)

    Ramos, Cinthia P.

    2001-01-01

    The binary Zr-Fe phase diagram revision, performed by Arias et al., accepted the intermetallic Zr 2 Fe crystalline structure as tetragonal and determined that the presence of a third element like oxygen, nitrogen or carbon, stabilizes a cubic phase. Nevitt et al. studying Ti, Zr and Hf alloys with transition metals as second or third element and ternary systems with oxygen as third element, systematized the occurrence of phases with a cubic Ti 2 Ni type crystalline structure. From previous studies in the Zr-Nb-Fe system, it is an agreed fact that Nb presence in the Zr 2 Fe intermetallic stabilizes a cubic Ti 2 Ni type phase. The purpose of the present work is to determine the stability range of the Zr 2 Fe intermetallic with Nb contents, the existence range of the ternary cubic Ti 2 Ni type phase (designated Λ) and the corresponding two-phase region. We analyze as cast and heat treated (800 C degrees) Zr-Nb-Fe alloys with 35 atomic % Fe and Nb contents between 0.5 and 15 atomic %. The determination and characterization of the phases is made by optical and scanning electron microscopy, X-ray diffraction microprobe analysis and Moessbauer Spectroscopy. Joining these techniques together it is found, among many other things, that the Zr 2 Fe phase would accept up to around 0.5 atomic % Nb in solution and that the two-phase region Zr 2 Fe+Λ would be stable in the (0.5 - 3.5) Nb atomic % range. It is proposed as well a 800 C degrees section of the ternary (Zr-Nb-Fe) in the studied region. (author) [es

  2. Note: Resonance magnetoelectric interactions in laminate of FeCuNbSiB and multilayer piezoelectric stack for magnetic sensor

    Science.gov (United States)

    Li, Jianqiang; Lu, Caijiang; Xu, Changbao; Zhong, Ming

    2015-09-01

    This paper develops a simple miniature magnetoelectric (ME) laminate FeCuNbSiB/PZT-stack made up of magnetostrictive Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB) foils and piezoelectric Pb(Zr, Ti)O3 (PZT) multilayer stack vibrator. Resonant ME interactions of FeCuNbSiB/PZT-stack with different layers of FeCuNbSiB foil (L) are investigated in detail. The experimental results show that the ME voltage coefficient reaches maximum value of 141.5 (V/cm Oe) for FeCuNbSiB/PZT-stack with L = 6. The AC-magnetic sensitivities can reach 524.29 mV/Oe and 1.8 mV/Oe under resonance 91.6 kHz and off-resonance 1 kHz, respectively. The FeCuNbSiB/PZT-stack can distinguish small dc-magnetic field of ˜9 nT. The results indicate that the proposed ME composites are very promising for the cheap room-temperature magnetic field sensing technology.

  3. Glass forming ability and magnetic properties of Co(40.2−x)Fe(20.1+x)Ni6.7B22.7Si5.3Nb5 (x=0–10) bulk metallic glasses produced by suction casting

    International Nuclear Information System (INIS)

    Sarlar, Kagan; Kucuk, Ilker

    2015-01-01

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) have a supercooled liquid region (∆T x ) of about 44 K. The saturation magnetizations (J s ) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J s 0.62−0.81 T with a low H c of 2−289 A/m of the alloys

  4. Influence of the spacer layer on microstructure and magnetic properties of [NdFeB/(NbCu)]xn thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, H. [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania); Grigoras, M. [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania); Urse, M. [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)]. E-mail: urse@phys-iasi.ro

    2007-09-15

    Some results concerning the influence of the composition and thickness of NbCu spacer layer on the microstructure and magnetic properties of multilayer [NdFeB/(NbCu)]xn films, in view of their utilization for manufacturing the thin film permanent magnets are presented. A comparison between the microstructure and magnetic properties of NdFeB single layer and [NdFeB/(NbCu)]xn multilayer is also presented. The multilayer [NdFeB/(NbCu)]xn thin films with the thickness of the NdFeB layer of 180nm and the thickness of the NbCu spacer layer of 3nm, exhibit good hard magnetic characteristics such as coercive force H{sub c} of about 1510kA/m and the remanence ratio M{sub r}/M{sub s} of about 0.8.

  5. Influence of the spacer layer on microstructure and magnetic properties of [NdFeB/(NbCu)]xn thin films

    International Nuclear Information System (INIS)

    Chiriac, H.; Grigoras, M.; Urse, M.

    2007-01-01

    Some results concerning the influence of the composition and thickness of NbCu spacer layer on the microstructure and magnetic properties of multilayer [NdFeB/(NbCu)]xn films, in view of their utilization for manufacturing the thin film permanent magnets are presented. A comparison between the microstructure and magnetic properties of NdFeB single layer and [NdFeB/(NbCu)]xn multilayer is also presented. The multilayer [NdFeB/(NbCu)]xn thin films with the thickness of the NdFeB layer of 180nm and the thickness of the NbCu spacer layer of 3nm, exhibit good hard magnetic characteristics such as coercive force H c of about 1510kA/m and the remanence ratio M r /M s of about 0.8

  6. Surface Properties of a Nanocrystalline Fe-Ni-Nb-B Alloy After Neutron Irradiation

    Science.gov (United States)

    Pavùk, Milan; Sitek, Jozef; Sedlačková, Katarína

    2014-09-01

    The effect of neutron radiation on the surface properties of the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy was studied. Firstly, amorphous (Fe0.25Ni0.75)81Nb7B12 ribbon was brought by controlled annealing to the nanocrystalline state. After annealing, the samples of the nanocrystalline ribbon were irradiated in a nuclear reactor with neutron fluences of 1×1016cm-2 and 1 × 1017cm-2 . By utilizing the magnetic force microscopy (MFM), topography and a magnetic domain structure were recorded at the surface of the ribbon-shaped samples before and after irradiation with neutrons. The results indicate that in terms of surface the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy is radiation-resistant up to a neutron fluence of 1 × 1017cm-2 . The changes in topography observed for both irradiated samples are discussed

  7. Magnetic susceptibility of CoFeBSiNb alloys in liquid state

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V., E-mail: vesidor@mail.ru [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Hosko, J. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V.; Rozkov, I.; Uporova, N. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Svec, P.; Janickovic, D.; Matko, I.; Svec Sr, P. [Institute of Physics SAS, Bratislava (Slovakia); Malyshev, L. [Ural Federal University, Ekaterinburg (Russian Federation)

    2014-03-15

    The influence of small additions of gallium and antimony on magnetic susceptibility of the bulk glass forming Co{sub 47}Fe{sub 20.9}B{sub 21.2}Si{sub 4.6}Nb{sub 6.3} alloy was studied in a wide temperature range up to 1830 K by the Faraday’s method. The undercooling for all the samples was measured experimentally. Both Ga and Sb additions were found to increase liquidus and solidification temperatures. However, gallium atoms strengthen interatomic interaction in the melts, whereas antimony atoms reduce it. - Highlights: • Bulk metallic glasses from CoFeBSiNb-based alloys were produced as in situ composites. • Magnetic susceptibility of these alloys was measured in a wide temperature range including liquid state. • Undercooling of these melts was measured experimentally. • Ga additions strengthen interatomic interaction in BMG melts, whereas Sb atoms reduce it.

  8. Magneto-Impedance behavior of Co-Fe-Nb-Si-B-based ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Partha; Mohanta, O.; Pal, S.K.; Panda, A.K. [National Metallurgical Laboratory, Council of Scientific and Industrial Research, Jamshedpur 831007 (India); Mitra, A., E-mail: amitra@nmlindia.or [National Metallurgical Laboratory, Council of Scientific and Industrial Research, Jamshedpur 831007 (India)

    2010-04-15

    The giant magneto-impedance of melt spun Co{sub x}Fe{sub 72-x}Nb{sub 4}Si{sub 4}B{sub 20}(x=10, 20, 36, 50) amorphous and nanostructured ribbons have been investigated. Alloys have been optimized at the driving current amplitude, frequency and found that amorphous ribbon of nominal composition of Co{sub 36}Fe{sub 36}Nb{sub 4}Si{sub 4}B{sub 20} shown maximum GMI ratio of 13%. The behaviour of the driving current amplitude on the GMI behaviour was studied and the sample was optimized for driving current amplitude, I{sub ac}=10 mA. The frequency dependence of the GMI behaviour was studied for the ribbon sample Co{sub 36}Fe{sub 36}Nb{sub 4}Si{sub 4}B{sub 20} at frequency in the range of 100 kHz-1.2 MHz of the optimized driving current amplitude and it was found that the sample showed the maximum GMI behaviour at f=700 kHz. The optimized samples were Joule heated at the current density J=0-35 A/m{sup 2} for a period of 1 min. The GMI ratio initially increased then progressively deteriorated with J, but after a certain range it shows up to 16% of improvement in the magneto-impedance value due the increase of nanocrystalline volume fraction. The asymmetry in the GMI profile was observed for the sample Joule heated at J=1-5 A/m{sup 2} for 1 min.

  9. Electronic structure and magnetism of new ilmenite compounds for spintronic devices: FeBO{sub 3} (B = Ti, Hf, Zr, Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, R.A.P. [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Camilo, A. [Department of Physics, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Lazaro, S.R. de, E-mail: srlazaro@uepg.br [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil)

    2015-11-15

    First-principles calculations were performed in the framework of Density Functional Theory (DFT) within hybrid functional (B3LYP) to study the electronic structure and magnetic properties of new ilmenite FeBO{sub 3} (B=Ti, Hf, Zr, Si, Ge, Sn) materials. In particular, the magnetic exchange interaction between Fe{sup 2+} layers is dependent on the interlayer distance and it can be controlled by ionic radius of B-site cation. Thus, Fe(Ti, Si, Ge)O{sub 3} are antiferromagnetic materials, while Fe(Zr, Hf, Sn)O{sub 3} are ferromagnetic. We also argue that antiferromagnetic materials and FeZrO{sub 3} are convectional semiconductors, whereas FeHfO{sub 3} and FeSnO{sub 3} exhibit intrinsic half-metallic behavior, making them promising candidates for spintronic devices. - Highlights: • We study electronic structure and magnetism of new FeBO{sub 3} (B=Ti, Hf, Zr, Si, Ge, Sn) ilmenite materials. • We found that magnetic ordering of Fe-based ilmenite materials can be controlled by size of B-site cation. • Fe(Ti, Zr, Si, Ge)O{sub 3} are convectional semiconductors. • FeHfO{sub 3} and FeSnO{sub 3} exhibit intrinsic half-metallic behavior with potential application for spintronic devices.

  10. Effects of Dy and Nb on the magnetic properties and corrosion resistance of sintered NdFeB

    International Nuclear Information System (INIS)

    Yu, L.Q.; Wen, Y.H.; Yan, M.

    2004-01-01

    Dy and Nb were added into the sintered NdFeB magnets with the aim of improving their magnetic properties and corrosion resistance. It was found that intrinsic coercivity of magnets is promoted whilst remanence is reduced as a result of Dy addition. Simultaneous addition of Dy and Nb not only gives rise to greatly improved coercivity, but also suppresses the undesirable effect of Dy on the remanence. The optimum magnetic properties were achieved when 1.0% Dy and 1.5% Nb were incorporated. Moreover, corrosion resistance of NdFeB magnets improves with the increase in the content of Dy and Nb

  11. Study of the mechanical and magnetic properties of Fe{sub 61}Co{sub 10}Zr{sub 5-x}Hf{sub x}W{sub 2}Y{sub 2}B{sub 20} (x = 0 or 3) bulk amorphous and crystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nabialek, Marcin G. [Institute of Physics, Czestochowa University of Technology, 19 Armii Krajowej Av., 42-200 Czestochowa (Poland); Szota, Michal [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej Av., 42-200 Czestochowa (Poland); Dospial, Marcin J.

    2010-05-15

    The microstructure, thermal stability, mechanical and magnetic properties of Fe{sub 61}Co{sub 10}Zr{sub 5-x}Hf{sub x}W{sub 2}Y{sub 2}B{sub 20} (where x = 0 or 3) bulk metallic glasses (BMG) and their crystalline equivalents were investigated. The crystalline materials were smelted on a copper mould using an electric arc; their amorphous equivalents were prepared using the induction suction casting method (ISC). All samples investigated were in the form of plates with dimensions of 10x10x0.5mm. From X-ray diffraction and Moessbauer spectroscopy, it was found that both investigated alloys prepared using this method have an amorphous structure. From magnetic measurements obtained by a vibrating sample magnetometer (VSM), it was shown that all measured samples displayed soft magnetic properties with relatively high saturation of the magnetization. The thermal stability and glass-forming ability (GFA) for investigated alloys were derived from differential scanning calorimetry (DSC) curves. The measurements of mechanical properties for amorphous alloys were found to be better than those for crystalline alloys with the same atomic composition. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Glass forming ability and magnetic properties of Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses produced by suction casting

    Energy Technology Data Exchange (ETDEWEB)

    Sarlar, Kagan [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Physics Department, Kamil Ozdag Faculty of Sciences, Karamanoglu Mehmetbey University, YunusEmre Campus, 70100 Karaman (Turkey); Kucuk, Ilker, E-mail: ikucuk@uludag.edu.tr [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)

    2015-01-15

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) have a supercooled liquid region (∆T{sub x}) of about 44 K. The saturation magnetizations (J{sub s}) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J{sub s} 0.62−0.81 T with a low H{sub c} of 2−289 A/m of the alloys.

  13. Texturing for bulk α-Fe/Nd2Fe14B nanocomposites with enhanced magnetic properties

    International Nuclear Information System (INIS)

    Lou, L.; Hou, F.C.; Wang, Y.N.; Cheng, Y.; Li, H.L.; Li, W.; Guo, D.F.; Li, X.H.; Zhang, X.Y.

    2014-01-01

    In the present study, the texturing of bulk α-Fe/Nd 2 Fe 14 B nanocomposites produced from Nd-lean amorphous Nd x Fe 92.5−x Cu 1.5 B 6 (x=9 to 11.5 at%) via a hot deformation under a uniaxial stress of ∼350 MPa at 973 K has been studied. An enhanced (00l) texture of the hard phase is observed with increasing Nd content, which results in an increase in the magnetic anisotropy of the nanocomposite magnets. As a result, both the coercivity and the remanence of the magnets increase simultaneously with increasing Nd content from x=9–11.5 at%, yielding a significant enhancement of the maximum energy product from (BH) max =13.2 to 17.5 MGOe in the direction parallel to stress axis. - Highlights: • Textured bulk α-Fe/Nd 2 Fe 14 B nanocomposites have been produced from Nd-lean alloys. • Nd content has an effect on the texturing of α-Fe/Nd 2 Fe 14 B nanocomposite magnets. • An enhanced (00l) texture of hard phase is observed with increasing Nd content. • Both the coercivity and remanence increase simultaneously with Nd content

  14. Perpendicular magnetic anisotropy of CoFeB\\Ta bilayers on ALD HfO2

    Directory of Open Access Journals (Sweden)

    Bart F. Vermeulen

    2017-05-01

    Full Text Available Perpendicular magnetic anisotropy (PMA is an essential condition for CoFe thin films used in magnetic random access memories. Until recently, interfacial PMA was mainly known to occur in materials stacks with MgO\\CoFe(B interfaces or using an adjacent crystalline heavy metal film. Here, PMA is reported in a CoFeB\\Ta bilayer deposited on amorphous high-κ dielectric (relative permittivity κ=20 HfO2, grown by atomic layer deposition (ALD. PMA with interfacial anisotropy energy Ki up to 0.49 mJ/m2 appears after annealing the stacks between 200°C and 350°C, as shown with vibrating sample magnetometry. Transmission electron microscopy shows that the decrease of PMA starting from 350°C coincides with the onset of interdiffusion in the materials. High-κ dielectrics are potential enablers for giant voltage control of magnetic anisotropy (VCMA. The absence of VCMA in these experiments is ascribed to a 0.6 nm thick magnetic dead layer between HfO2 and CoFeB. The results show PMA can be easily obtained on ALD high-κ dielectrics.

  15. Effect of Nb on magnetic and mechanical properties of TbDyFe alloys

    Science.gov (United States)

    Wang, Naijuan; Liu, Yuan; Zhang, Huawei; Chen, Xiang; Li, Yanxiang

    2018-03-01

    The intrinsic brittleness in giant magnetostrictive material TbDyFe alloy has devastating influence on the machinability and properties of the alloy, thus affecting its applications. The purpose of this paper is to study the mechanical properties of the TbDyFe alloy by alloying with Nb element. The samples (Tb0.3Dy0.7)xFe2xNby (y = 0, 0.01, 0.04, 0.07, 0.1; 3x + y = 1) were melted in an arc melting furnace under high purity argon atmosphere. The microstructure, magnetostrictive properties and mechanical performance of the alloys were studied systematically. The results showed that NbFe2 phases were observed in the alloys with the addition of Nb. Moreover, both the NbFe2 phases and rare earth (RE)-rich phases were increased with the increasing of Nb element. The mechanical properties results revealed that the fracture toughness of the alloy with the addition of Nb enhanced 1.5-5 times of the Nb-free alloy. Both the NbFe2 phase and the RE-rich phase had the ability to prevent crack propagation, so that they can strengthen the REFe2 body. However, NbFe2 phase is a paramagnetic phase, which can reduce the magnetostrictive properties of the alloy by excessive precipitation.

  16. Glass formation ability, structure and magnetocaloric effect of a heavy rare-earth bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jo, C.-L. [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)], E-mail: jochollong@163.com; Xia Lei; Ding Ding; Dong Yuanda; Gracien, Ekoko [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)

    2008-06-30

    The glass formation ability, the structure and the magnetocaloric effect of the bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy were investigated. Bulk metallic glassy (BMGs) alloys were prepared by a copper-mold casting method. The glass forming ability and their structure were studied by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The XRD analysis revealed that the as-cast cylinder of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed fully amorphous structure in 2 mm diameter. The DSC revealed that the bulk cylinder of the Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed a distinct glass transition temperature and a relatively wide supercooled liquid region before crystallization. SQUID investigated the magnetic properties and the entropy changes. The Curie temperature of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} BMGs alloy was about 130 K, but the maximum magnetic entropy changes(-{delta}S{sub M}) showed at about 125 K, a little lower than the Curie temperature 130 K. The reason could probably be due to the presence of a little amount of nanocrystalline particles between amorphous phases. The BMG alloy has the characteristic of second-order transition (SOT) on Arrott plots. The results showed that the amorphous sample had a relatively improved magnetocaloric effect, indicating that the amorphous alloy could be considered as a candidate for magnetic refrigeration applications in the temperature interval range of 100-200 K.

  17. Microstructure and tensile properties of Fe-40 at. pct Al alloys with C, Zr, Hf, and B additions

    Science.gov (United States)

    Gaydosh, D. J.; Draper, S. L.; Nathal, M. V.

    1989-01-01

    The influence of small additions of C, Zr, and Hf, alone or in combination with B, on the microstructure and tensile behavior of substoichiometric FeAl was investigated. Tensile properties were determined from 300 to 1100 K on powder which was consolidated by hot extrusion. All materials possessed some ductility at room temperature, although ternary additions generally reduced ductility compared to the binary alloy. Adding B to the C- and Zr-containing alloys changed the fracture mode from intergranular to transgranular and restored the ductility to approximately 5 percent elongation. Additions of Zr and Hf increased strength up to about 900 K. Fe6Al6Zr and Fe6Al6Hf precipitates, both with identical body-centered tetragonal structures, were identified as the principal second phase in these alloys. Strength decreased steadily as temperature increased above 700 K, as diffusion-assisted mechanisms became operative. Although all alloys had similar strengths at 1100 K, Hf additions significantly improved high-temperature ductility by suppressing cavitation.

  18. Magnetic and structural properties of the Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B system prepared by arc melting

    Energy Technology Data Exchange (ETDEWEB)

    Oyola Lozano, D., E-mail: doyola@ut.edu.co [University of Tolima, Department of Physics (Colombia); Zamora, L. E.; Perez Alcazar, G. A. [University of Valle, Department of Physics (Colombia); Rojas, Y. A.; Bustos, H. [University of Tolima, Department of Physics (Colombia); Greneche, J. M. [Universite du Maine, Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087 (France)

    2006-04-15

    In this work the magnetic and structural properties are investigated by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B powdered alloys with x = 0, 2 and 4 prepared by arc melting. The Moessbauer spectra of the samples were fitted with several contributions from: Nd{sub 2}Fe{sub 14}B, {alpha}-Fe and a paramagnetic phase associated with Nd{sub 1.1}Fe{sub 4}B{sub 4} for x = 0 and additionally from NbFeB and Nd{sub 2}Fe{sub 17} for x = 2 and x = 4. The relative fractions of {alpha}-Fe and Nd{sub 2}Fe{sub 14}B are smaller for x = 4 than for x = 0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd{sub 2}Fe{sub 17} increases. The {alpha}-Fe grain size slightly decreases while that of the Nd{sub 2}Fe{sub 14}B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization.

  19. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    International Nuclear Information System (INIS)

    Ma, Y.L.; Liu, X.B.; Nguyen, V.V.; Poudyal, N.; Yue, M.; Liu, J.P.

    2016-01-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd 2 Fe 14 B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH) max of 10 MGOe was obtained at NdFeB content of 50 wt%.

  20. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.L. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); College of Metallurgical and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Liu, X.B.; Nguyen, V.V.; Poudyal, N. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Yue, M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, J.P., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2016-08-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd{sub 2}Fe{sub 14}B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH){sub max} of 10 MGOe was obtained at NdFeB content of 50 wt%.

  1. 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.

  2. Co-based soft magnetic bulk glassy alloys optimized for glass ...

    Indian Academy of Sciences (India)

    diameter of 5 mm by conventional copper mould casting method. It reveals ... For example, Co43Fe20Ta5.5B31.5 glassy alloy with a ... coercive force (Hc) of 0.25 A m. −1 ..... [7] Lu Z P, Liu C T, Thompson J R and Porter W D 2004 Phys. Rev.

  3. Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

    International Nuclear Information System (INIS)

    Babilas, Rafał; Hawełek, Łukasz; Burian, Andrzej

    2014-01-01

    The local atomic structure of the Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe 3 B, Fe 23 B 6 and bcc Fe structures are also discussed. - Graphical abstract: Pair distribution functions (a) and best-fit model and experimental radial distribution functions for Fe 80 B 20 (b), Fe 70 Nb 10 B 20 (c) and Fe 62 Nb 8 B 30 (d) metallic glasses. - Highlights: • The short-range ordering in the Fe-based metallic glasses is presented. • The results of RDF function have been analyzed using the least-squares method. • The Fe–Fe, Fe–B, Fe–Nb or Nb–B contributions are involved in coordination spheres. • The structural unit is distorted triangular prism containing B, Fe or Nb atoms. • Similarities of atomic arrangement in glassy and crystalline structures are discussed

  4. Soft Magnetic Properties of Nanocrystalline Fe-M-(B and/or O)(M=Group IV A, V A Elements) Alloy Films

    OpenAIRE

    Hayakawa, Y.; Makino, A.; Inoue, A.; Masumoto, T.

    1996-01-01

    In Fe-M-(B and/or O)(M=group IV A, V A elements) alloy films, nanocrystalline bcc phase are formed by annealing the amorphous single phase for Fe-M-B films, whereas the bcc nanocrystals are already formed in an as-deposited state for Fe-M-O or Fe-M-B-O) films. Among Fe-M-B films with various M elements, Fe-(Zr, Hf, Nb, Ta)-B alloy films exhibit high saturation magnetization (Is) above 1.4 T and high relative permeability (|μ|) above 1000 at 1MHz. The highest |μ| of 3460 at 1MHz is obtained fo...

  5. Improved magnetic properties and thermal stabilities of Pr-Nd-Fe-B sintered magnets by Hf addition

    Science.gov (United States)

    Jiang, Qingzheng; Lei, Weikai; Zeng, Qingwen; Quan, Qichen; Zhang, Lili; Liu, Renhui; Hu, Xianjun; He, Lunke; Qi, Zhiqi; Ju, Zhihua; Zhong, Minglong; Ma, Shengcan; Zhong, Zhenchen

    2018-05-01

    Nd2Fe14B-type permanent magnets have been widely applied in various fields such as wind power, voice coil motors, and medical instruments. The large temperature dependence of coercivity, however, limits their further applications. We have systematically investigated the magnetic properties, thermal stabilities and coercivity mechanisms of the (Pr0.2Nd0.8)13Fe81-xB6Hfx (x=0, 0.5) nanocrystalline magnets fabricated by a spark plasma sintering (SPS) technique. The results indicate that the influence of Hf addition is significant on magnetic properties and thermal stabilities of the (PrNd)2Fe14B-type sintered magnets. It is shown that the sample with x = 0.5 at 300 K has much higher coercivity and remanent magnetization than those counterparts without Hf. The temperature coefficients of remanence (α) and coercivity (β) of the (Pr0.2Nd0.8)13Fe81-xB6Hfx magnets are improved significantly from -0.23 %/K, -0.57 %/K for the sample at x = 0 to -0.17 %/K, -0.49 %/K for the sample at x = 0.5 in the temperature range of 300-400 K. Furthermore, it is found out that the domain wall pinning mechanism is more likely responsible for enhancing the coercivity of the (Pr0.2Nd0.8)13Fe81-xB6Hfx magnets.

  6. Hard magnetic properties of rapidly annealed NdFeB thin films on Nb and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; Evans, J.; O'Shea, M.J.; Du Jianhua

    2001-01-01

    NdFeB thin films of the form A (20 nm)/NdFeB(d nm)/A(20 nm), where d ranges from 54 to 540 nm and the buffer layer A is Nb or V were prepared on a Si(1 0 0) substrate by magnetron sputtering. The hard Nd 2 Fe 14 B phase is formed by a 30 s rapid anneal or a 20 min anneal. Average crystallite size ranged from 20 to 35 nm with the rapidly annealed samples having the smaller crystallite size. These samples also exhibited a larger coercivity and energy product than those treated by a 20 min vacuum anneal. A maximum coercivity of 26.3 kOe at room temperature was obtained for a Nb/NdFeB (180 nm)/Nb film after a rapid anneal at 725 deg. C. Initial magnetization curves indicate magnetization rotation rather than nucleation of reverse domains is important in the magnetization process. A Brown's equation analysis of the coercivity as a function of temperature allowed us to compare the rapidly annealed and 20 min annealed samples. This analysis suggests that rapid annealing gives higher quality crystalline grains than the 20 min annealed sample leading to the observed large coercivity in the rapidly annealed samples

  7. Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}: Two stannide intermetallics with low-dimensional iron sublattices

    Energy Technology Data Exchange (ETDEWEB)

    Calta, Nicholas P. [Department of Chemistry, Northwestern University (United States); Kanatzidis, Mercouri G., E-mail: m-kanatzidis@northwestern.edu [Department of Chemistry, Northwestern University (United States); Materials Science Division, Argonne National Laboratory (United States)

    2016-04-15

    This article reports two new Hf-rich intermetallics synthesized using Sn flux: Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}. Hf{sub 3}Fe{sub 4}Sn{sub 4} adopts an ordered variant the Hf{sub 3}Cu{sub 8} structure type in orthorhombic space group Pnma with unit cell edges of a=8.1143(5) Å, b=8.8466(5) Å, and c=10.6069(6) Å. Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}, on the other hand, adopts a new structure type in Cmc2{sub 1} with unit cell edges of a=5.6458(3) Å, b=35.796(2) Å, and c=8.88725(9) Å for x=0. It exhibits a small amount of phase width in which Sn substitutes on one of the Fe sites. Both structures are fully three-dimensional and are characterized by pseudo one- and two-dimensional networks of Fe–Fe homoatomic bonding. Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} exhibits antiferromagnetic order at T{sub N}=46(2) K and its electrical transport behavior indicates that it is a normal metal with phonon-dictated resistivity. Hf{sub 3}Fe{sub 4}Sn{sub 4} is also an antiferromagnet with a rather high ordering temperature of T{sub N}=373(5) K. Single crystal resistivity measurements indicate that Hf{sub 3}Fe{sub 4}Sn{sub 4} behaves as a Fermi liquid at low temperatures, indicating strong electron correlation. - Graphical abstract: Slightly different growth conditions in Sn flux produce two new intermetallic compounds: Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}. - Highlights: • Single crystals of both Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} were grown using Sn flux. • The crystal structures were determined using single crystal X-ray diffraction. • The Fe moments in Hf{sub 3}Fe{sub 4}Sn{sub 4} display AFM order below T{sub N}=373 K. • The Fe moments in Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} display AFM order below T{sub N}=46 K.

  8. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    Science.gov (United States)

    Ma, Y. L.; Liu, X. B.; Nguyen, V. V.; Poudyal, N.; Yue, M.; Liu, J. P.

    2016-08-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd2Fe14B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%.

  9. Fatigue and strain effects in NbTi, Nb3Sn, and V2(Hf, Zr) multifilamentary superconductors

    International Nuclear Information System (INIS)

    Kuroda, T.; Wada, H.; Tachikawa, K.

    1988-01-01

    The effects of cyclic strain on critical current were studied in NbTi, bronze processed Nb 3 Sn, and composite diffusion processed V 2 (Hf,Zr) multifilamentary wires. No appreciable changes in critical current were found in NbTi wires until just prior to fatigue-induced fracture. Critical current degradation was also not observed in Nb 3 Sn or V 2 (Hf,Zr) as long as the wires were strained below the reversible limit strain. For strains beyond this limit strain the critical current was first degraded by an increasing number of cycles and then remained constant after a certain cycle number was passed

  10. Role of Nb in glass formation of Fe–Cr–Mo–C–B–Nb BMGs

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Fuqiang, E-mail: fuqiangzhai@gmail.com [Departament Física Aplicada, EETAC, Universitat Politècnica Catalunya-BarcelonaTech, Esteve Terradas 5, 08860 Castelldefels (Spain); Pineda, Eloi [Departament Física i Enginyeria Nuclear, ESAB, Universitat Politècnica Catalunya- BarcelonaTech, Esteve Terradas 8, 08860 Castelldefels (Spain); Duarte, M. Jazmín [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf (Germany); Crespo, Daniel [Departament Física Aplicada, EETAC, Universitat Politècnica Catalunya-BarcelonaTech, Esteve Terradas 5, 08860 Castelldefels (Spain)

    2014-08-01

    Highlights: • The Fe{sub 46}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Nb{sub 4} BMG of 3 mm Ø was produced for the first time. • The compressive strength of Fe–Cr–Mo–C–B–Nb BMG is reported. • The fragility parameter of Fe–Cr–Mo–C–B–Nb BMG was studied. • The microscopic mechanism is explained by E{sub g}, E{sub x}, E{sub p} and m parameters. - Abstract: A new Fe-based bulk metallic glass with superior glass-forming ability (GFA), Fe{sub 46}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Nb{sub 4}, was developed based on the Fe–Cr–Mo–C–B alloy system by minor addition of Nb. The effects of Nb addition on glass formation of the Fe{sub 50−x}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Nb{sub x} (x = 0, 2, 4 and 6 at.%) alloys were investigated. The optimum addition content of Nb was determined as 4 at.% by X-ray diffraction and differential scanning calorimeter analysis. A fully amorphous rod sample with 3 mm in diameter was produced by using commercial-grade raw materials and a copper mold casting technique. This alloy shows an ultimate compressive strength of 1920 MPa and Vicker’s hardness 1360 H{sub V}, which is two to three times that of conventional high strength steel and suggests a promising potential for applications combining outstanding corrosion and wear resistance properties. The crystallization kinetics studies found that the activation energies for glass transition, onset of crystallization and crystallization peak were higher than those of other reported Fe-based bulk metallic glasses. The value of the fragility parameter m for the Fe{sub 46}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Nb{sub 4} alloy was calculated to be 34, indicating that the Fe–Cr–Mo–C–B–Nb alloy system is a strong glass former according to the Angell’s classification scheme. It is inferred that the more sequential change in the atomic size, the generation of new atomic pairs with large negative heats of mixing and the amount of oxygen in the molten liquid

  11. Effects of surface crystallization and oxidation in nanocrystalline FeNbCuSiB(P) ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Butvinová, B., E-mail: beata.butvinova@savba.sk [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Butvin, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Brzózka, K. [Department of Physics, University of Technology and Humanities in Radom, Krasickiego 54, 26-600 Radom (Poland); Kuzminski, M. [Institute of Physics PAS, Al. Lotnikow 36/42, 02-668 Warsaw (Poland); Maťko, I.; Švec Sr, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Chromčíková, M. [Institute of Inorg. Chem. SAS, Centrum VILA, Študentská 2, 911 50 Trenčín (Slovakia)

    2017-02-15

    Si-poor Fe{sub 74}Nb{sub 3}Cu{sub 1}Si{sub 8}B{sub 14−x}P{sub x}, (x=0, 3) nanocrystalline ribbon-form alloys often form surfaces, which exert in-plane force on underlying ribbon interior when nanocrystallized in even modest presence of oxygen. Mostly unwanted hard-ribbon-axis magnetic anisotropy is standard result. Essential sources of the surface-caused stress have been sought and influence of P instead of B substitution on this effect was studied too. Preferred surface crystallization (PSC) was found to be the major reason. However P substitution suppresses PSC and promotes Fe-oxide formation, which eases the stress, softens the surfaces and provides different annealing evolution of surface properties. - Highlights: • Ar anneal of low-Si FeNbCuBSi ribbons produce surfaces that stress ribbon interior. • The stress comes mainly from preferred crystallization of surfaces. • Partial substitution of B by P changes annealing evolution of surface properties. • Without P, more crystalline surfaces significantly reduce ribbon's elasticity. • P suppresses surface crystallinity, promotes oxides and reduces mutual stress.

  12. Extraction behavior of Nb and Ta in HF solutions with tributyl phosphate

    International Nuclear Information System (INIS)

    Murakami, M.; Tsuto, S.; Ooe, K.; Goto, S.; Kudo, H.; Haba, H.; Kanaya, J.

    2013-01-01

    Extraction behavior of carrier-free Nb and Ta with tributyl phosphate (TBP) from HF solutions was studied by a batch method. Tantalum is extracted well to an organic phase, while Nb is left in an aqueous phase at 0.053-1.0 M HF concentrations. The similar extraction trends of Nb and Ta are shown in the solid phase extraction using a TBP resin. The extraction equilibria in the solid phase extraction are attained within ∼10 s. (author)

  13. Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

    2011-06-15

    Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

  14. Surface properties of a nanocrystalline Fe-Ni-Nb-B alloy after neutron irradiation

    International Nuclear Information System (INIS)

    Pavuk, M.; Sitek, J.; Sedlackova, K.

    2014-01-01

    In this work, we studied the impact of a neutron radiation on the surface properties of the nanocrystalline (Fe_0_._2_5Ni_0_._7_5)_8_1Nb_7B_1_2 alloy. Changes in topography and domain structure were observed by means of magnetic force microscopy (MFM). (authors)

  15. Exchange interactions in Fe/Y multilayers

    International Nuclear Information System (INIS)

    Elkabil, R.; Elkaidi, I.; Annouar, F.; Lassri, H.; Hamdoun, A.; Bensassi, B.; Berrada, A.; Krishnan, R.

    2005-01-01

    The magnetization of Fe/Y multilayers has been measured as a function of temperature. A bulk-like T 3/2 temperature dependence of the magnetization is observed for all multilayers in the temperature range 5-300 K. The spin-wave constant B is found to decrease inversely with t Fe . A simple theoretical model with exchange interactions only, and with non-interacting magnons, has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b , surface exchange interaction J s and the interlayer exchange interaction J I for various Fe layer thicknesses have been obtained

  16. Anion exchange behavior of Ti, Zr, Hf, Nb and Ta as homologues of Rf and Db in mixed HF-acetone solutions

    International Nuclear Information System (INIS)

    Aksenov, N.V.; Bozhikov, G.A.; Starodub, G.Ya.; Dmitriev, S.N.; Filosofov, D.V.; Jon Sun Jin; Radchenko, V.I.; Lebedev, N.A.; Novgorodov, A.F.

    2009-01-01

    We studied in detail the sorption behavior of Ti, Zr, Hf, Nb and Ta on AG 1 anion exchange resin in HF-acetone mixed solutions as a function of organic cosolvent and acid concentrations. Anion exchange behavior was found to be strongly acetone concentration dependent. The distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions. With increasing HF concentration, anion exchange equilibrium analysis indicated the formation of fluoride complexes of group-4 elements with charge -3 and Ta with charge -2. For Nb the slope of -2 increased up to -5. Optimal conditions for separation of the elements using AIX chromatography were found. Group-4 elements formed MF 7 3- (M = Ti, Zr, Hf) complexes whose sorption decreased Ti > Hf > Zr in reverse order of complex stability. This fact is of particular interest for studying ion exchange behavior of Rf compared to Ti. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed

  17. Effect of high-order multicomponent on formation and properties of Zr-based bulk glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, A., E-mail: ainouebmg@yahoo.co.jp [International Institute of Green Materials, Josai International University, Togane 283-8555 (Japan); School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Department of Physics, King Abdulaziz University, Jeddah 22254 (Saudi Arabia); Wang, Z.; Louzguine-Luzgin, D.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Han, Y. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Kong, F.L. [International Institute of Green Materials, Josai International University, Togane 283-8555 (Japan); Shalaan, E.; Al-Marzouki, F. [Department of Physics, King Abdulaziz University, Jeddah 22254 (Saudi Arabia)

    2015-07-25

    Highlights: • A multicomponent Zr{sub 55}Al{sub 10}Fe{sub 6}Co{sub 6}Ni{sub 6}Cu{sub 6}Pd{sub 6}Ag{sub 5} bulk glassy alloy was formed. • The high-order multiplication suppression of the decrease in mechanical strength. • The BGAs show good corrosion resistance and slow growth rate of primary precipitates. - Abstract: We examined the formation, thermal stability, mechanical properties and corrosion behavior of a multicomponent Zr{sub 55}Al{sub 10}Fe{sub 6}Co{sub 6}Ni{sub 6}Cu{sub 6}Pd{sub 6}Ag{sub 5} bulk glassy alloy, with the aim of clarifying the effect of high-order multiplication of the number of components on their properties. The bulk glassy alloy rods of 2 and 6 mm in diameter were formed by suction casting even at the low total content of typical glass-forming 3-d late transition metals like Co, Ni and Cu. The Vickers hardness is different in the center region and in the outer surface region. The difference seems to reflect the relaxation level of glassy structure. The Young’s modulus and the compressive fracture strength are nearly the same for the base Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30} alloy in spite of the existence of immiscible atomic pairs. Moreover, the multicomponent alloy exhibits better corrosion resistance than that for the base alloy. The glassy phase changes to a supercooled liquid state at 720 K and then starts to crystallize at 754 K with a single exothermic peak, in contrast to the appearance of a wide supercooled liquid region for the base alloy. The primary crystalline phase precipitates with very short incubation time and very low growth rate, which are different from those for the base alloy. The extremely low growth rate of the crystallites is presumably due to the reduction of diffusivity of late transition metal elements resulting from multiplication. Thus, the high-order multiplication has the features of (1) the maintenance of high glass-forming ability even at the lower Co, Ni and Cu content and in the absence of

  18. Beta decomposition of (Hf/sub x/Zr/sub 1-x/)80Nb20 ternary alloys

    International Nuclear Information System (INIS)

    Jones, W.B.; Taggart, R.; Polonis, D.H.

    1978-01-01

    The processes of beta decomposition have been examined in ternary alloys of the form (Hf/sub x/Zr/sub 1-x/) 80 Nb 20 to determine the influence of Hf additions to a basic Zr 80 Nb 20 composition. In the chill cast condition, Hf additions have been found to decrease the temperature coefficient of electrical resistivity from a value of -0.0015%/K for the binary Zr 80 Nb 20 alloy to a value of -0.011%/K for a (Hf 50 Zr 50 ) 80 Nb 20 ternary alloy. This change is explained in terms of the bcc lattice instability typical of Ti, Zr, and Hf alloys. The Hf additions enhance the kinetics of omega-phase precipitation during aging at 648 K. The aging of a (Hf 05 Zr 95 ) 80 Nb 20 alloy for 12 h results in the precipitation of a high volume fraction of cuboidal shaped omega-phase particles. A phase separation which results in the formation of solute lean discs (β/sub l/) occurs together with the precipitation of the omega-phase. These discs formed both randomly within the matrix and heterogeneously along dislocations and at grain boundaries

  19. Diffusion of Nb in Fe and in some Fe alloys

    International Nuclear Information System (INIS)

    Kurokawa, S.; Ruzzante, J.E.; Hey, A.M.; Dyment, F.

    1981-01-01

    Diffusion data of microalloying elements such as Nb, V, Ti, are required when analysing the transformation and recrystallization behaviour of HSLA steels in order to optimize grain refinement and precipitation hardening. The diffusion behaviour of Nb in pure Fe, Fe 1.5 Mn, Fe 0.6 Si and Fe 1.5 Mn 0.6 Si has been measured between 1080 and 1200 0 C. Results indicate that Si increases Nb diffusivity while Mn decreases it. The sequence of diffusion coeficients values is: D sup(Nb) sub(Fe 1.5 Mn) [pt

  20. Bulk metallic glasses and high entropy alloys for reprocessing applications

    International Nuclear Information System (INIS)

    Kamachi Mudali, U.; Jayaraj, J.

    2016-01-01

    Recent breakthroughs in materials engineering have generated complex alloys that retain a glassy state in bulk form (bulk metallic glasses or BMGs) via ingot casting. High corrosion resistance is expected for BMGs (amorphous) as they are free from defects associated with the crystalline state such as grain boundaries, dislocations and stacking faults. Compared with conventional alloys containing one or two principal elements, the recently developed HEAs are usually composed of five or more elements with equimolar or near equimolar elemental fractions, which forms single solid solution phase. These HEAs exhibit excellent microstructural stability with better mechanical, wear and corrosion resistance properties as they are essentially single phase. Reprocessing of spent fuel from the fast breeder reactor involves the use of high concentration of (11.5 M) nitric acid under boiling conditions for the dissolution of the fuel. Conventional AISI type 304LSS and nitric acid grade 304L stainless steel would undergo inter-granular corrosion under these conditions and cannot be used for the fabrication of dissolver vessel. Currently titanium is used and zirconium alloys are proposed for future dissolver applications. Thus searching for newer materials with higher corrosion resistance suggests metallic glasses and HEAs for critical components of the dissolver application. Several Zr-based glassy alloys with different microstructural states and Ni-Nb based glassy alloys and TiZrHfNbTa HEA were cast and characterized for microstructure and corrosion resistance in nitric acid medium. From these studies, factors such as the corrosive environment (nitric acid, chloride and fluoride), and the presence of passivating elements in the alloy were emphasized for better corrosion resistance of BMGs and HEA. Attempts were also made to prepare coatings of Zr-and Ni-based glassy alloys on 304LSS by laser based deposition technique and their corrosion properties were evaluated. (author)

  1. 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

  2. Electric resistivity and thermoelectricity of Ni-Nb-Zr and Ni-Nb-Zr-H glassy alloys

    Science.gov (United States)

    Fukuhara, Mikio; Inoue, Akihisa

    2010-09-01

    Electric resistivity ρ and thermoelectric power S of Ni 36Nb 24Zr 40 and (Ni 0.36Nb 0.24Zr 0.4) 90H 10 glassy alloys were investigated in temperature region between 1.5 and 300 K. After resistivity curves of both alloys increase gradually with decreasing temperature down to around 6 K, they dropped suddenly and then reached zero resistivity at 2.1 K, leading to superconductivity. Linear curve with negative TCR of ρ vs T2 and slight increase of S/ T in temperature region down to around 6 K clearly reveal Fermi-liquid phenomenon in electronic state for both alloys independent of hydrogen content.

  3. Electric resistivity and thermoelectricity of Ni-Nb-Zr and Ni-Nb-Zr-H glassy alloys

    International Nuclear Information System (INIS)

    Fukuhara, Mikio; Inoue, Akihisa

    2010-01-01

    Electric resistivity ρ and thermoelectric power S of Ni 36 Nb 24 Zr 40 and (Ni 0.36 Nb 0.24 Zr 0.4 ) 90 H 10 glassy alloys were investigated in temperature region between 1.5 and 300 K. After resistivity curves of both alloys increase gradually with decreasing temperature down to around 6 K, they dropped suddenly and then reached zero resistivity at 2.1 K, leading to superconductivity. Linear curve with negative TCR of ρ vs T 2 and slight increase of S/T in temperature region down to around 6 K clearly reveal Fermi-liquid phenomenon in electronic state for both alloys independent of hydrogen content.

  4. Corrosion Characteristics of Ti-29Nb-xHf Ternary Alloy for Biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Pak, Sun Young; Choi, Han Chul [Chosun Univ., Kwangju (Korea, Republic of)

    2015-12-15

    The Cp-Ti and Ti-6Al-4V alloys were widely used for dental materials due to their mechanical properties and good corrosion resistance. However, Cp-Ti was known as bio-inert materials, Ti-6Al-4V alloy has a problem such as high Young modulus, potential loss of the surrounding bone, and to the release of potentially toxic ions from the alloy. To overcome this problem, Ti alloys containing Nb and Hf elements have been used for biomaterials due to low toxicity and high corrosion resistance. Especially, alloying element of Nb was known as β phase stabilizer. The β phase alloy was widely used to replace currently used implant materials. The corrosion resistances of Ti-29Nb-xHf ternary alloys were dependent on Hf content in oral environment solution.

  5. Bulk photovoltaic effect in epitaxial (K, Nb) substituted BiFeO3 thin films

    Science.gov (United States)

    Agarwal, Radhe; Zheng, Fan; Sharma, Yogesh; Hong, Seungbum; Rappe, Andrew; Katiyar, Ram

    We studied the bulk photovoltaic effect in epitaxial (K, Nb) modified BiFeO3 (BKFNO) thin films using theoretical and experimental methods. Epitaxial BKFNO thin films were grown by pulsed laser deposition (PLD). First, we have performed first principles density function theory (DFT) using DFT +U method to calculate electronic band structure, including Hubbard-Ueff (Ueff =U-J) correction into Hamiltonian. The electronic band structure calculations showed a direct band gap at 1.9 eV and a defect level at 1.7 eV (in a 40 atom BKFNO supercell), sufficiently lower in comparison to the experimentally observed values. Furthermore, the piezoforce microscopy (PFM) measurements indicated the presence of striped polydomains in BKFNO thin films. Angle-resolved PFM measurements were also performed to find domain orientation and net polarization directions in these films. The experimental studies of photovoltaic effect in BKNFO films showed a short circuit current of 59 micro amp/cm2 and open circuit voltage of 0.78 V. We compared our experimental results with first principles shift current theory calculations of bulk photovoltaic effect (BPVE).The synergy between theory and experimental results provided a realization of significant role of BPVE in order to understand the photovoltaic mechanism in ferroelectrics.

  6. Preparation, thermal stability, and magnetic properties of Fe-Zr-Mo-W-B bulk metallic glass

    International Nuclear Information System (INIS)

    Liu, D.Y.; Sun, W.S.; Wang, A.M.; Zhang, H.F.; Hu, Z.Q.

    2004-01-01

    A bulk metallic glass (BMG) cylinder of Fe 60 Co 8 Zr 10 Mo 5 W 2 B 15 with a diameter of 1.5 mm was prepared by copper mould casting of industrial raw materials. The amorphous state and the crystallization behavior were investigated by X-ray diffraction (XRD). The thermal stability parameters, such as glass transition temperature (T g ), crystallization temperature (T x ), supercooled liquid region (ΔT x ) between T g and T x , and reduced glass transition temperature T rg (T g /T m ) were measured by differential scanning calorimetry (DSC) to be 891, 950, 59 K, and 0.62, respectively. The crystallization process took place through a single stage, and involved crystallization of the phases α-Fe, ZrFe 2 , Fe 3 B, MoB 2 , Mo 2 FeB 2 , and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 1023 K, 50 K above the DSC peak temperature of crystallization. Moessbauer spectroscopy was studied for this alloy. The spectra exhibit a broadened and asymmetric doublet-like structure that indicated paramagnetic behavior and a fully amorphous structure. α-Fe was found in the amorphous matrix for a cylinder with a diameter of 2.5 mm. The success of synthesis of the Fe-based bulk metallic glass from industrial materials is important for the future progress in research and practical application of new bulk metallic glasses

  7. Hard magnetic off-stoichiometric (Fe,Sb){sub 2+x}Hf{sub 1-x} intermetallic phase

    Energy Technology Data Exchange (ETDEWEB)

    Goll, D.; Gross, T.; Loeffler, R.; Pflanz, U.; Vogel, T.; Kopp, A.; Grubesa, T.; Schneider, G. [Aalen University, Materials Research Institute (Germany)

    2017-09-15

    By high-throughput screening the ternary Fe-Hf-Sb system, off-stoichiometric (Fe,Sb){sub 2+x}Hf{sub 1-x} with a composition of Fe60.0-Hf26.5-Sb13.5 with high potential as hard magnetic phase is discovered. By quantitative domain structure analysis, promising intrinsic properties of J{sub s} ∝ 1 T, K{sub 1} ∝ 1.5 MJ m{sup -3} are found at room temperature. By magnetometry, bulk intrinsic properties of J{sub s} ∝ 0.7 T, K{sub 1} ∝ 1.4 MJ m{sup -3} are found. Alloying elements like Co or Mn turns out to be an effective adjusting screw on the crystal structure and ferromagnetic behavior. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Fabrication of an Fe80.5Si7.5B6Nb5Cu Amorphous-Nanocrystalline Powder Core with Outstanding Soft Magnetic Properties

    Science.gov (United States)

    Zhang, Zongyang; Liu, Xiansong; Feng, Shuangjiu; Rehman, Khalid Mehmood Ur

    2018-03-01

    In this study, the melt spinning method was used to develop Fe80.5Si7.5B6Nb5Cu amorphous ribbons in the first step. Then, the Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline core with a compact microstructure was obtained by multiple processes. The main properties of the magnetic powder core, such as micromorphology, thermal behavior, permeability, power loss and quality factor, have been analyzed. The obtained results show that an Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline duplex core has high permeability (54.8-57), is relatively stable at different frequencies and magnetic fields, and the maximum power loss is only 313 W/kg; furthermore, it has a good quality factor.

  9. Trapped magnetic field in a (NdFeB)–(MgB2) pair-type bulk magnet

    International Nuclear Information System (INIS)

    Aldica, Gheorghe; Burdusel, Mihail; Badica, Petre

    2014-01-01

    Highlights: • Dense MgB 2 discs were obtained by ex-situ Spark Plasma Sintering. • A NdFeB–MgB 2 pair-type bulk magnet was tested for different working conditions. • The polarity of the NdFeB permanent magnet influences macro flux jumps of MgB 2 . • Trapped field of the pair was 2.45 T (20 K) and 3.3 T (12 K). - Abstract: Superconducting bulk discs, S, of 20 mm in diameter and 3.5 or 3.3 mm thickness of MgB 2 (pristine or added with cubic BN, respectively) with density above 97% were prepared by Spark Plasma Sintering. Discs were combined in a pair-type sandwich-like arrangement with a permanent NdFeB axially magnetised magnet, PM (∼0.5 T). Measurement of the trapped field, B tr , with temperature, time, and the reduction rate of the applied magnetic field was performed using a Hall sensor positioned at the centre between the superconductor and the permanent magnet. It is shown that the permanent magnet with certain polarity favors higher trapped field of the superconductor owing to suppression of flux jumps specific for high density MgB 2 samples. The B tr of the PM–S pair was 2.45 T (20 K) and 3.3 T (12 K)

  10. MFM study of NdFeB and NdFeB/Fe/NdFeB thin films

    International Nuclear Information System (INIS)

    Gouteff, P.C.; Folks, L.; Street, R.

    1998-01-01

    Domain structures of NdFeB thin films, ranging in thickness between 1500 and 29 nm, have been studied qualitatively by magnetic force microscopy (MFM). Samples were prepared using a range of sputtering conditions resulting in differences in properties such as texture, coercivity and magnetic saturation. MFM images of all the films showed extensive interaction domain structures, similar to those observed in nanocrystalline bulk NdFeB. An exchange-coupled NdFeB/Fe/NdFeB trilayer with layer thicknesses 18 nm/15 nm/18 nm, respectively, was also examined using MFM. (orig.)

  11. Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications

    Science.gov (United States)

    Park, Seon-Yeong; Choe, Han-Cheol

    2018-02-01

    In this study, Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetrons sputtering for dental applications were studied using different experimental techniques. Mn coating films were formed on Ti-29Nb-xHf alloys by a radio frequency magnetron sputtering technique for 0, 1, 3, and 5 min at 45 W. The microstructure, composition, and phase structure of the coated alloys were examined by optical microscopy, field emission scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The microstructure of Ti-29Nb alloy showed α" phase in the needle-like structure and Ti-29Nb-15Hf alloy showed β phase in the equiaxed structure. As the sputtering time increased, the circular particles of Mn coatings on the Ti-29Nb alloy increased at inside and outside surfaces. As the sputtering time increased, [Mn + Ca/P] ratio of the plasma electrolytic oxidized films in Ti- 29Nb-xHf alloys increased. The corrosion potential (Ecorr) of Mn coatings on the Ti-29Nb alloy showed higher than that of Mn coatings on the Ti-29Nb-15Hf alloy. The passive current density (Ipass) of the Mn coating on the Ti-29Nb alloy and Mn coatings on the Ti-29Nb-15Hf alloy was less noble than the non-Mn coated Ti-29Nb and Ti-29Nb-15Hf alloys surface.

  12. Electric Field Gradients at Hf and Fe Sites in Hf2Fe Recalculated

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Cekic, B.; Novakovic, N.; Koteski, V.; Milosevic, Z.

    2004-01-01

    The electric field gradients (EFG) of the Hf 2 Fe intermetallic compound were calculated using the full-potential linearized augmented plain-wave (FP-LAPW) method as embodied in the WIEN 97 code. The obtained values are compared with other ab-initio calculations and on a qualitative basis with the previously reported experimental data obtained from TDPAC. The calculated results, -23.1.10 21 V/m 2 and 2.7.10 21 V/m 2 for Hf 48f and Fe 32e position, respectively, are in excellent agreement with experimental data (23.4.10 21 V/m 2 and 2.7.10 21 V/m 2 ), better than those reported in earlier calculations. The calculated EFG for Hf 16c position (4.2.10 21 V/m 2 ) is stronger than the experimental one (1.1.10 21 V/m 2 ).

  13. Structure and magnetic properties of NdFeB thin films with Cr, Mo, Nb, Ta, Ti, and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; O'Shea, M.J.

    2000-01-01

    Layers of NdFeB of the form A(20 nm)/NdFeB(d nm)/A(20 nm) where A represents Cr, Mo, Nb, Ta, Ti, V were prepared on a silicon substrate by magnetron sputtering. The purpose is to determine how (i) the chosen buffer layer and (ii) NdFeB layer thickness d (especially d 2 Fe 14 B with no preferred crystalline orientation. Our highest coercivities occur for buffer layer elements from row five of the periodic table, 20 kOe (1600 kA/m) in a Nb buffered sample with d of 180 nm and 17 kOe (1350 kA/m) in a Mo buffered sample with d of 180 nm. Buffer layers from row four (Ti, V, and Cr) and row six (Ta) all give lower coercivities. Our largest energy product, 10.3 MG-Oe (82 kJ/m 3 ), is obtained for the Mo buffered sample. Average Nd 2 Fe 14 B crystallite size for this sample is 27 nm. Only the Cr and Ti buffered films show a large coercivity (≥2 kOe) for d of 54 nm with the Cr films showing the highest coercivity, 2.7 kOe (215 kA/m). In films subjected to a rapid thermal anneal (anneal time 30 s) we find that both the coercivity and energy product are larger than in samples subjected to a 20 min anneal. In our Nb buffered systems we obtain coercivities as high as 26.3 kOe (2090 kA/m) after a rapid thermal anneal

  14. Thermodynamic analysis and evaluation of the nitrogen solubility in liquid Nb and Fe-Nb alloys

    International Nuclear Information System (INIS)

    Qiu Caian

    1994-01-01

    Experimental information on the nitrogen solubility in liquid Nb and Fe-Nb alloys has been critically analysed and then utilized to evaluate the thermodynamic properties of the Nb-N and Fe-Nb-N liquid phases on the basis of thermodynamic models of Gibbs energy. A thermodynamic description of the Fe-Nb-N liquid phase was obtained, which has been used to calculate the N solubility in comparison with experimental results. The effect of an addition of Nb on the temperature dependence of the N solubility in liquid Fe has been examined by comparing with the effect of the Cr and V additions. It has been shown that the N solubility in liquid Nb and Fe-Nb alloys under various conditions is well described by the present calculation. (orig.)

  15. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  16. Moessbauer spectroscopy characterization of Zr-Nb-Fe phases

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C.P. [CONICET, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina)]. E-mail: ciramos@cnea.gov.ar; Granovsky, M.S. [CAC-CNEA, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina); Saragovi, C. [CAC-CNEA, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina)

    2007-02-01

    The aim of this work was the characterization of the ternary phases and of those coming from the corresponding binary systems in the Zr-Nb-Fe diagram by means of Moessbauer spectroscopy. This is part of a complete study involving a tentative isothermal section at 900 deg. C of the center of the Zr-Nb-Fe diagram which will be published elsewhere. Zr-Nb-Fe alloys with Nb contents between 5 and 50 at% and Fe contents between 10 and 60 at% were analyzed after a heat treatment at 900 deg. C for 4 month. Moessbauer characterization of the phases was complemented by optical and scanning electron microscopies, X-ray diffraction and electron microprobe analysis. From the obtained results it can be inferred that Fe in both of the Laves phases present in this system (Zr(FeNb){sub 2} and (ZrNb)Fe{sub 2}) sees different environments, producing quadrupole splitting and hyperfine field distributions, respectively. Two types of body centered cubic {beta} phases (Zr-rich and Nb-rich) were found having noticeable differences in their Moessbauer parameters. Furthermore it was shown that the ternary Fe(NbZr){sub 2} compound would show magnetic character at low temperatures. Concentration dependence of the hyperfine parameters and their relations with the lattice parameters contributed to the structural characterization of the phases.

  17. Moessbauer spectroscopy characterization of Zr-Nb-Fe phases

    International Nuclear Information System (INIS)

    Ramos, C.P.; Granovsky, M.S.; Saragovi, C.

    2007-01-01

    The aim of this work was the characterization of the ternary phases and of those coming from the corresponding binary systems in the Zr-Nb-Fe diagram by means of Moessbauer spectroscopy. This is part of a complete study involving a tentative isothermal section at 900 deg. C of the center of the Zr-Nb-Fe diagram which will be published elsewhere. Zr-Nb-Fe alloys with Nb contents between 5 and 50 at% and Fe contents between 10 and 60 at% were analyzed after a heat treatment at 900 deg. C for 4 month. Moessbauer characterization of the phases was complemented by optical and scanning electron microscopies, X-ray diffraction and electron microprobe analysis. From the obtained results it can be inferred that Fe in both of the Laves phases present in this system (Zr(FeNb) 2 and (ZrNb)Fe 2 ) sees different environments, producing quadrupole splitting and hyperfine field distributions, respectively. Two types of body centered cubic β phases (Zr-rich and Nb-rich) were found having noticeable differences in their Moessbauer parameters. Furthermore it was shown that the ternary Fe(NbZr) 2 compound would show magnetic character at low temperatures. Concentration dependence of the hyperfine parameters and their relations with the lattice parameters contributed to the structural characterization of the phases

  18. Trapped magnetic field in a (NdFeB)–(MgB{sub 2}) pair-type bulk magnet

    Energy Technology Data Exchange (ETDEWEB)

    Aldica, Gheorghe [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania); Burdusel, Mihail [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania); Faculty of Materials Science and Engineering, ‘‘Politehnica’’ University of Bucharest, Splaiul Independentei 316, 060042 Bucharest (Romania); Badica, Petre, E-mail: badica2003@yahoo.com [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania)

    2014-10-15

    Highlights: • Dense MgB{sub 2} discs were obtained by ex-situ Spark Plasma Sintering. • A NdFeB–MgB{sub 2} pair-type bulk magnet was tested for different working conditions. • The polarity of the NdFeB permanent magnet influences macro flux jumps of MgB{sub 2}. • Trapped field of the pair was 2.45 T (20 K) and 3.3 T (12 K). - Abstract: Superconducting bulk discs, S, of 20 mm in diameter and 3.5 or 3.3 mm thickness of MgB{sub 2} (pristine or added with cubic BN, respectively) with density above 97% were prepared by Spark Plasma Sintering. Discs were combined in a pair-type sandwich-like arrangement with a permanent NdFeB axially magnetised magnet, PM (∼0.5 T). Measurement of the trapped field, B{sub tr}, with temperature, time, and the reduction rate of the applied magnetic field was performed using a Hall sensor positioned at the centre between the superconductor and the permanent magnet. It is shown that the permanent magnet with certain polarity favors higher trapped field of the superconductor owing to suppression of flux jumps specific for high density MgB{sub 2} samples. The B{sub tr} of the PM–S pair was 2.45 T (20 K) and 3.3 T (12 K)

  19. Fe3Nb3N precipitates of the Fe3W3C type in Nb stabilized ferritic stainless steel

    International Nuclear Information System (INIS)

    Malfliet, A.; Van den Broek, W.; Chassagne, F.; Mithieux, J.-D.; Blanpain, B.; Wollants, P.

    2011-01-01

    Highlights: → The precipitation in Nb stabilized ferritic stainless steel at 950 deg. C is investigated. → We characterized the Fe 3 Nb 3 X precipitates with SAED, EELS, WDS and AES. → We found that Fe 3 Nb 3 X precipitates are stabilized by N and not by C or O. → This insight is new and important for future development of this type of steel grade. - Abstract: A Nb stabilized ferritic stainless steel with 0.45 wt.%Nb, 82 ppm C and 170 ppm N is investigated to reveal the nature of the precipitates present at 950 deg. C. In particular, Fe 3 Nb 3 X precipitates of the Fe 3 W 3 C type are analyzed with WDS and EELS to determine the light elements X stabilizing this phase in the steel. According to WDS on large precipitates after 500 h at 950 deg. C, the Fe 3 Nb 3 X phase contains 10.4 at.% N, 1.2 at.% O and 1.0 at.% C. Auger Electron Spectroscopy on the same precipitates confirms the presence of N. In addition, it is revealed that the C and O peaks observed with WDS result from surface contamination as they disappear after Ar sputtering. The presence of a N peak in the EELS spectra of small Fe 3 Nb 3 X precipitates which have formed after 6 min at 950 deg. C indicate that N stabilizes this phase already from the initial precipitation stage. With this analysis it is demonstrated that N is an effective stabilizer of Fe 3 Nb 3 X precipitates in ferritic stainless steels. The formation of this phase should therefore be considered when predicting the precipitation behavior of Nb in industrial Nb stabilized ferritic stainless steels containing residual N.

  20. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2018-03-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  1. Isoelectronic substitutions and aluminium alloying in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

    Science.gov (United States)

    von Rohr, Fabian O.; Cava, Robert J.

    2018-03-01

    High-entropy alloys (HEAs) are a new class of materials constructed from multiple principal elements statistically arranged on simple crystallographic lattices. Due to the large amount of disorder present, they are excellent model systems for investigating the properties of materials intermediate between crystalline and amorphous states. Here we report the effects of systematic isoelectronic replacements, using Mo-Y, Mo-Sc, and Cr-Sc mixtures, for the valence electron count 4 and 5 elements in the body-centered cubic (BCC) Ta-Nb-Zr-Hf-Ti high-entropy alloy (HEA) superconductor. We find that the superconducting transition temperature Tc strongly depends on the elemental makeup of the alloy, and not exclusively its electron count. The replacement of niobium or tantalum by an isoelectronic mixture lowers the transition temperature by more than 60%, while the isoelectronic replacement of hafnium, zirconium, or titanium has a limited impact on Tc. We further explore the alloying of aluminium into the nearly optimal electron count [TaNb] 0.67(ZrHfTi) 0.33 HEA superconductor. The electron count dependence of the superconducting Tc for (HEA)Al x is found to be more crystallinelike than for the [TaNb] 1 -x(ZrHfTi) x HEA solid solution. For an aluminum content of x =0.4 the high-entropy stabilization of the simple BCC lattice breaks down. This material crystallizes in the tetragonal β -uranium structure type and superconductivity is not observed above 1.8 K.

  2. Structural relaxations in the bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}

    Energy Technology Data Exchange (ETDEWEB)

    Błoch, K., E-mail: 23kasia1@wp.pl; Nabiałek, M.; Gondro, J.

    2017-05-01

    The paper presents studies of annealing effect on the disaccommodation phenomenon in bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}. The investigated sample was prepared by suction-casting method in the form of rod. The annealing process has been performed at temperature well below the crystallisation temperature. The amorphous structure has been confirmed using X-ray diffractometer. The susceptibility and its disaccommodation were determined using completely automated set up. The disaccommodation curve was decomposed into three elementary processes, each of them was described by Gaussian distribution of relaxation times. The obtained results indicate that the disaccommodation phenomenon in studied alloy is related with directional ordering of atom pairs near the free volumes; this is in agreement with H. Kronmüller's theorem.

  3. Evolution of Fe environments in mechanically alloyed Fe–Nb–(B) compositions

    Energy Technology Data Exchange (ETDEWEB)

    Blázquez, J.S., E-mail: jsebas@us.es; Ipus, J.J.; Conde, C.F.; Conde, A.

    2014-12-05

    Highlights: • Nb is rapidly incorporated to the nanocrystalline FeNb(B) matrix. • B inclusions remains even after long milling times. • B is helpful to enhance the comminuting of crystallites. - Abstract: Nanocrystalline alloys of nominal composition Fe{sub 85}Nb{sub 5}B{sub 10} were produced by mechanical alloying from a mixture of elemental powders. Two commercial boron structures were used: amorphous and crystalline. In addition, a third composition Fe{sub 94.4}Nb{sub 5.6} was prepared for comparison. X-ray diffraction and Mössbauer spectroscopy were used to describe the evolution of the microstructure and Fe environments as a function of the milling time. Whereas Nb is rapidly incorporated into the nanocrystalline matrix, boron inclusions remain even after long milling times. The presence of boron is found to enhance the comminuting of crystallites.

  4. FeSiBP bulk metallic glasses with high magnetization and excellent magnetic softness

    Energy Technology Data Exchange (ETDEWEB)

    Makino, Akihiro [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)], E-mail: amakino@imr.tohoku.ac.jp; Kubota, Takeshi; Chang, Chuntao [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Makabe, Masahiro [Makabe R and D Co., Ltd., 3-1-25 Nagatake, Sendai 983-0036 (Japan); Inoue, Akihisa [Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2008-10-15

    Fe-based amorphous alloy ribbons are one of the major soft magnetic materials, because of their superior magnetic properties such as the relatively high saturation magnetization (J{sub s}) of 1.5-1.6 T and good magnetic softness. However, the preparation of the ordinary amorphous magnetic alloys requires cooling rates higher than 10{sup 4} K/s due to the low glass-forming ability (GFA) and thus restricts the material outer shape. Recently, Fe-metalloid-based bulk metallic glasses (BMGs) containing glass-forming elements such as Al, Ga, Nb, Mo, Y and so forth have been developed. These alloys have high GFA, leading to the formation of BMG rod with diameters of mm-order. However, the glass-forming metal elements in BMGs result in a remarkable decrease in magnetization. Basically, J{sub s} depends on Fe content; hence, high J{sub s} requires high Fe content in the Fe-based amorphous alloys or BMGs. On the other hand, high GFA requires a large amount of glass-forming elements in the alloys, which results in lower Fe content. Therefore, in substances, the coexistence of high J{sub s} and high GFA is difficult. Since this matter should be immensely important from academia to industry in the material field, a great deal of effort has been devoted; however, it has remained unsolved for many years. In this paper, we present a novel Fe-rich FeSiBP BMG with high J{sub s} of 1.51 T comparable to the ordinary Fe-Si-B amorphous alloy now in practical use as well as with high GFA leading to a rod-shaped specimen of 2.5 mm in diameter, obtained by Cu-mold casting in air.

  5. First principles study the stability and mechanical properties of MC (M = Ti, V, Zr, Nb, Hf and Ta) compounds

    International Nuclear Information System (INIS)

    Liu, YangZhen; Jiang, YeHua; Zhou, Rong; Feng, Jing

    2014-01-01

    Highlights: • The stability and elastic constants of carbides are studied by first principles. • The rules of modulus of MC compounds are discussed by their group. • The hardness of carbides is estimated in this paper at the first time. -- Abstract: The first principles calculations based on density functional theory (DFT) were adopted to investigate the stability, elastic constants, chemical bonding, Debye temperature and hardness of MC (M = Ti, V, Zr, Nb, Hf and Ta) compounds. The cohesive energy and formation enthalpy of these carbides indicate that they are thermodynamically stable structures. The population analysis was used to discuss the chemical bonding of these carbides. The elastic constants and moduli of these compounds were calculated. The results show that the bulk moduli of the carbides of transition metals from the fourth group (TiC, ZrC, HfC) are lower than the fifth group (VC, NbC, TaC). However, the Young’s moduli of the carbides from fourth group are higher than the fifth group. The hardness of compounds was estimated using a semi empirical hardness theory

  6. Anomalous superconducting spin-valve effect in NbN/FeN/Cu/FeN/FeMn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Tae Jong; Kim, Dong Ho [Yeungnam University, Gyeongsan (Korea, Republic of)

    2017-09-15

    We have studied magnetic and transport properties of NbN/FeN/Cu/FeN/FeMn spin-valve structure. In-plane magnetic moment exhibited typical hysteresis loops of spin valves in the normal state of NbN film at 20 K. On the other hand, the magnetic hysteresis loop in the superconducting state exhibited more complex behavior in which exchange bias provided by antiferrmagnetic FeMn layer to adjacent FeN layer was disturbed by superconductivity. Because of this, the ideal superconducting spin-valve effect was not detected. Instead the stray field originated from unsaturated magnetic states dominated the transport properties of NbN/FeN/Cu/FeN/FeMn multilayer.

  7. Influence of boron vacancies on phase stability, bonding and structure of MB2 (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2 type structure

    International Nuclear Information System (INIS)

    Dahlqvist, Martin; Rosen, Johanna; Jansson, Ulf

    2015-01-01

    Transition metal diborides in hexagonal AlB 2 type structure typically form stable MB 2 phases for group IV elements (M  =  Ti, Zr, Hf). For group V (M  =  V, Nb, Ta) and group VI (M  =  Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on the B-site in hexagonal MB 2 and its influence on the phase stability and the structure for TiB 2 , ZrB 2 , HfB 2 , VB 2 , NbB 2 , TaB 2 , CrB 2 , MoB 2 , and WB 2 using first-principles calculations. Selected phases are also analyzed with respect to electronic and bonding properties. We identify trends showing that MB 2 with M from group V and IV are stabilized when introducing B-vacancies, consistent with a decrease in the number of states at the Fermi level and by strengthening of the B–M interaction. The stabilization upon vacancy formation also increases when going from M in period 4 to period 6. For TiB 2 , ZrB 2 , and HfB 2 , introduction of B-vacancies have a destabilizing effect due to occupation of B–B antibonding orbitals close to the Fermi level and an increase in states at the Fermi level. (paper)

  8. Investigation of (Fe,Co)NbB-Based Nanocrystalline Soft Magnetic Alloys by Lorentz Microscopy and Off-Axis Electron Holography.

    Science.gov (United States)

    Zheng, Changlin; Kirmse, Holm; Long, Jianguo; Laughlin, David E; McHenry, Michael E; Neumann, Wolfgang

    2015-04-01

    The relationship between microstructure and magnetic properties of a (Fe,Co)NbB-based nanocrystalline soft magnetic alloy was investigated by analytical transmission electron microscopy (TEM). The microstructures of (Fe0.5Co0.5)80Nb4B13Ge2Cu1 nanocrystalline alloys annealed at different temperatures were characterized by TEM and electron diffraction. The magnetic structures were analyzed by Lorentz microscopy and off-axis electron holography, including quantitative measurement of domain wall width, induction, and in situ magnetic domain imaging. The results indicate that the magnetic domain structure and particularly the dynamical magnetization behavior of the alloys strongly depend on the microstructure of the nanocrystalline alloys. Smaller grain size and random orientation of the fine particles decrease the magneto-crystalline anisotropy and suggests better soft magnetic properties which may be explained by the anisotropy model of Herzer.

  9. Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

    Science.gov (United States)

    Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

    2018-04-01

    TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

  10. Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

    Science.gov (United States)

    Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

    2018-06-01

    TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

  11. High Nb, Ta, and Al creep- and oxidation-resistant austenitic stainless steel

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Yamamoto, Yukinori [Oak Ridge, TN; Liu, Chain-tsuan [Oak Ridge, TN

    2010-07-13

    An austenitic stainless steel HTUPS alloy includes, in weight percent: 15 to 30 Ni; 10 to 15 Cr; 2 to 5 Al; 0.6 to 5 total of at least one of Nb and Ta; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1 W; up to 0.5 Cu; up to 4 Mn; up to 1 Si; 0.05 to 0.15 C; up to 0.15 B; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni wherein said alloy forms an external continuous scale comprising alumina, nanometer scale sized particles distributed throughout the microstructure, said particles comprising at least one composition selected from the group consisting of NbC and TaC, and a stable essentially single phase fcc austenitic matrix microstructure, said austenitic matrix being essentially delta-ferrite-free and essentially BCC-phase-free.

  12. Enhanced photorefractive properties in Hf, Ce and Cu co-doped LiNbO{sub 3} crystals for holographic application

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tao, E-mail: tzhang_hit02@yahoo.com [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Postdoctoral Research Station of Mechanical Engineering, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001 (China); Wang, Xin; Geng, Tao; Tong, Chengguo [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Kang, Chong [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Postdoctoral Research Station of Mechanical Engineering, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2015-04-25

    Graphical abstract: Correlation spots of 200 holograms in a Hf, Ce and Cu co-doped LiNbO{sub 3}. - Highlights: • Several doped LiNbO{sub 3} crystals with various level of Hf doping were grown by Cz method. • IR peak shift is attributed to the complex defect change at different level of Hf. • Enhanced photorefractive properties have been got with higher Hf-doping level. • Reduced defect and increased photoconductivity are responsible for optical properties. • 200 holograms’ experiment is realized in a coherent volume 0.073 cm{sup 3}. - Abstract: Hf, Ce and Cu co-doped LiNbO{sub 3} crystals with various level of Hf doping were grown in air by a conventional Cz method. The infrared spectra were measured to discuss the defect structures and the mechanism of the absorption peak shift in these crystals. The light-induced scattering of the crystals was evaluated by the transmitted light method. The influence of the Hf-doping level on the photorefractive properties of Hf, Ce and Cu co-doped LiNbO{sub 3} crystals was studied via two-beam coupling. It is found that proper doping Hf is an efficient method to enhance the comprehensive photorefractive properties of the LiNbO{sub 3}. Using one of these crystals as medium, 200 holograms storage and correlation experiments based on angle fractal multiplexing have been realized in a coherent volume 0.073 cm{sup 3}. Moreover the diffraction efficiency is uniform and the storage density has reached 2.2 Gb/cm{sup 3}.

  13. Amorphization of Fe-Nb by mechanical alloying

    International Nuclear Information System (INIS)

    Yang, J.Y.; Zhang, T.J.; Cui, K.; Li, X.G.; Zhang, J.

    1996-01-01

    Elemental powder mixtures of Fe x Nb 1-x were mechanically alloyed in a planetary ball mill. Powders milled for different times were characterized by X-ray diffraction, transmission and scanning electron microscopy, differential thermal analysis and microhardness measurement. The results show that powders with 0.30≤x≤0.70 could be amorphized after 30 h milling; the maximum hardness (Hv) of milled Fe 50 Nb 50 powders attained was 1490. Based on a thermodynamical analysis, the glass forming range of the Fe-Nb system was calculated, and found to agree with the experimental result very well. (orig.)

  14. Upper critical fields in multifilamentary NbTi alloy superconducting wires

    International Nuclear Information System (INIS)

    Watanabe, Kazuo; Muto, Yoshio; Noto, Koshichi.

    1991-01-01

    In order to improve the high field performance of superconducting magnets, the upper critical field B c2 for practical multifilamentary alloy wires of NbTi, NbTiTa and NbTiHf were examined in respect with the usage of a pressurized superfluid cooling technique. The addition of Ta or Hf to NbTi enhanced by 0.5 T for B c2 at 1.8 K. Although the addition of a heavy element such as Ta or Hf has been regarded as suppressing Pauli-paramagnetism so far, it was found that the mechanism for B c2 enhancement by Hf addition is different from that by Ta addition. (author)

  15. Study of the magnetic interaction in nanocrystalline Pr-Fe-Co-Nb-B permanent magnets

    Science.gov (United States)

    Dospial, M.; Plusa, D.; Ślusarek, B.

    2012-03-01

    The magnetic properties of an isotropic, epoxy resin bonded magnets made from Pr-Fe-Co-Nb-B powder were investigated. The magnetization reversal process and magnetic parameters were examined by measurements of the initial magnetization curve, major and minor hysteresis loops and sets of recoil curves. From the initial magnetization curve and the field dependencies of the reversible and irreversible magnetization components derived from the recoil loops it was found that the magnetization reversal process is the combination of the nucleation of reversed domains and pinning of domain walls at the grain boundaries and the reversible rotation of magnetization vector in single domain grains. The interactions between grains were studied by means of δM plots. The nonlinear behavior of δM curve approve that the short range intergrain exchange coupling interactions are dominant in a field up to the sample coercivity. The interaction domains and fine magnetic structure were revealed as the evidence of exchange coupling between soft α-Fe and hard magnetic Nd2Fe14B grains.

  16. Effect of Co addition on the magnetic properties and microstructure of FeNbBCu nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Lin [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Yang, Weiming [School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Men, He [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Wang, Anding, E-mail: anding@nimte.ac.cn [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Chang, Chuntao [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Shen, Baolong, E-mail: blshen@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-12-01

    Through gradient substitution of Co for Fe, the magnetic properties and microstructures of (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} (x=0.1, 0.2, 0.3, 0.4, 0.5) nanocrystalline alloys were investigated. Because of the strong ferromagnetic exchange coupling between Co and Fe, substantial improvement in saturation magnetization was achieved with proper levels of Co addition. Meanwhile, the Curie temperature increased noticeably with increasing Co addition. After heat treatment, the (Fe{sub 0.9}Co{sub 0.1}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloy showed a refined microstructure with an average grain size of 10–20 nm, exhibiting a comparatively high saturation magnetization of 1.82 T and a lower coercivity of 12 A/m compared to other Hitperm-type alloys with higher Co contents. Additionally, the Curie temperature reached 1150 K upon introduction of Co. As the soft magnetic properties are strengthened by adding a small amount of Co, the combination of fine, soft magnetic properties and low cost make this nanocrystalline alloy a potential magnetic material. - Highlights: • New (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloys are successfully synthesized. • Minor Co addition improves the Curie temperature of (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} alloy system. • (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloys exhibit high saturation magnetization above 1.82 T.

  17. Magnetic and surface properties of Fe-Nb (Mo, V)-Cu-B-Si ribbons

    International Nuclear Information System (INIS)

    Butvinova, B.; Butvin, P.; Svec, P. Sr.; Matko, I.; Svec, P.; Janickovic, D.; Kadlecikova, M.

    2014-01-01

    The rapidly quenched Finemet (FeNbCuBSi) ribbons prepared by planar flow casting of the melt are very variable to obtain very good soft-magnetic properties. An appropriate thermal treatment leading to ultra-fine grain structure enables to attain such properties as desired for practical use. Increasing Fe percentage to the detriment of non-magnetic components lifts saturation induction above 1.3 T, preserves low coercivity and makes the alloy even cheaper to suit its mass production for use in power electronics. Apart from the plenty of benefits the ribbons show some risks. One of them is macroscopic heterogeneity, which often manifests via differences between surfaces and interior of a ribbon [3]. The surfaces squeeze (by in-plane force) the interior of many such ribbons and if engaged in magnetoelastic interaction, the force affects the resulting magnetic anisotropy [4]. Current research shows that changes of hysteresis loop shape come rather from surface crystallization and not from oxides namely in positively magnetostrictive alloys FeNbCuBSi known as low- Si Finemets. The object of this work is to verify whether the substitution of another element instead of Nb (usually incorporated as the grain-growth blocker) can change surface properties and affects the resulting magnetic properties. We chose V and Mo instead of Nb. Oxides, oxyhydroxides and a possible squeezing layer was looked for after higher temperature annealing which ensures partially nanocrystalline structure. (authors)

  18. Resistencia a la corrosión a alta temperatura de recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por APS

    Directory of Open Access Journals (Sweden)

    José Luis Tristancho-Reyes

    2014-12-01

    Full Text Available La corrosión a alta temperatura de las tuberías utilizadas en equipos generadores de vapor (calderas ha sido reconocida como un grave problema que trae consigo el adelgazamiento de éstas y, por consiguiente, la falla de los equipos. En la última década se han incrementado las investigaciones que involucran recubrimientos protectores que ayudan de alguna manera a prolongar la vida útil de estos equipos. Esta investigación determinó el comportamiento de los recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por proyección térmica asistida por plasma (APS sobre la aleación SA213 – T22 (2¼Cr – 1Mo, en un ambiente corrosivo de 80%V2O5–20%K2SO4 a 800°C. Los valores de la cinética de corrosión fueron determinados mediante resistencia a la polarización lineal (RPL y espectroscopia de impedancia electroquímica (EIE. Los resultados obtenidos muestran una menor cinética de corrosión en el recubrimiento NiCrFeNbMoTiAl que la presentada por el recubrimiento NiCrAlY, corroborado por Microscopia Electrónica de Barrido (MEB.

  19. Influence of shape and thickness on the levitation force of YBaCuO bulk HTS over a NdFeB guideway

    International Nuclear Information System (INIS)

    Ren Zhongyou; Wang Jiasu; Wang Suyu; Jiang He; Zhu Min; Wang Xiaorong; Song Honghai

    2003-01-01

    Levitation forces of YBaCuO bulk high temperature superconductors (HTS) with different shape and size over a NdFeB guideway were studied. Here, the concentrating magnetic field of the NdFeB guideway was 1.2 T, and the YBaCuO bulk HTSs include three cylindrical samples with different diameter and thickness and one hexagonal sample. The maximum levitation force is as high as 85.3 N at a gap of 5 mm between the bottom surface of YBaCuO bulk HTS and the top surface of the NdFeB guideway, where the applied magnetic field is about 0.8 T. The results show that the shape and the size have large influences on the levitation force of YBaCuO bulk HTSs

  20. The magnetic, structure and mechanical properties of rapidly solidified (Nd{sub 7}Y{sub 2.5})-(Fe{sub 64.5}Nb{sub 3})-B{sub 23} nanocomposite permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Zubair; Tao Shan; Ma Tianyu; Zhao Guoliang [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 312007 (China); Yan Mi, E-mail: mse_yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 312007 (China)

    2011-09-08

    The Nd{sub 7}Y{sub 2.5}Fe{sub 64.5}Nb{sub 3}B{sub 23} nanocomposite permanent magnets in the form of rods with 2 mm in diameter have been developed by annealing the amorphous precursors produced by copper mold casting technique. The phase evolution, structure, magnetic and mechanical properties were investigated with X-ray diffractometry, differential scanning calorimetry, electron microscopy, magnetometry and universal uniaxial compression strength techniques. The heat treatment conditions under which the magnets attained maximum magnetic and mechanical properties have been established. The results indicate that magnet properties are sensitive to grain size and volume content of the magnetic phases present in the microstructure. The composite microstructure was mainly composed of soft {alpha}-Fe (20-30 nm) and hard Nd{sub 2}Fe{sub 14}B (45-65 nm) magnetic phase grains. The maximum coercivity of 959.18 kA/m was achieved with the magnets annealed at 760 deg. C whereas the highest remanence of 0.57 T was obtained with the magnets treated at 710 deg. C. The optimally annealed magnets possessed promising magnetic properties such as {sub j}H{sub c} of 891.52 kA/m, B{sub r} of 0.57 T, M{sub r}/M{sub s} = 0.68, (BH){sub max} of 56.8 kJ/m{sup 3} as well as the micro-Vickers hardness (H{sub v}) of 1138 {+-} 20 and compressive stress ({sigma}{sub f}) of 239 {+-} 10 MPa.

  1. Mossbauer studies of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    1996-01-01

    This paper reports a Mossbauer study of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy between 10 and 673 K. The Curie temperature Tc is found to be 620-+ 1 K. The temperature dependence of the reduced average hyperfine field can be explained on the basis of Handrich's model of amorphous ferromagnetism...

  2. Prediction study of structural, elastic and electronic properties of FeMP (M = Ti, Zr, Hf) compounds

    Science.gov (United States)

    Tanto, A.; Chihi, T.; Ghebouli, M. A.; Reffas, M.; Fatmi, M.; Ghebouli, B.

    2018-06-01

    First principles calculations are applied in the study of FeMP (M = Ti, Zr, Hf) compounds. We investigate the structural, elastic, mechanical and electronic properties by combining first-principles calculations with the CASTEP approach. For ideal polycrystalline FeMP (M = Ti, Zr, Hf) the shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy indexes, Pugh's criterion, elastic wave velocities and Debye temperature are also calculated from the single crystal elastic constants. The shear anisotropic factors and anisotropy are obtained from the single crystal elastic constants. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal.

  3. Identification of new phases in the Zr-Nb-Fe system

    International Nuclear Information System (INIS)

    Granovsky, Marta S.; Arias, Delia E.; Lena, Esteban M.

    1999-01-01

    Intermediate phases in the Zr - rich region of the Zr - Nb - Fe system have been investigated by X-ray diffraction, optical and electron microscopy and electron microanalysis. The chemical composition ranges of the alloys here studied were (52 - 97) at. % Zr, (14 - 0.9) at. % Nb and (38 - 0.6) at. % Fe. The phases found in this region were the solid solutions α(Zr) and β(Zr), the intermetallic Zr 3 Fe with less than 0.2 at. % Nb in solution, and two new ternary phases: (Zr + Nb) 2 Fe, identified as a cubic Ti 2 Ni - type structure and another compound with composition close to Zr - 12 at. % Nb - 50 at. % Fe. (author)

  4. Electronic Transport Behaviors due to Charge Density Waves in Ni-Nb-Zr-H Glassy Alloys

    Science.gov (United States)

    Fukuhara, Mikio; Umemori, Yoshimasa

    2013-11-01

    The amorphous Ni-Nb-Zr-H glassy alloy containing subnanometer-sized icosahedral Zr5 Nb5Ni3 clusters exhibited four types of electronic phenomena: a metal/insulator transition, an electric current-induced voltage oscillation (Coulomb oscillation), giant capacitor behavior and an electron avalanche with superior resistivity. These findings could be excluded by charge density waves that the low-dimensional component of clusters, in which the atoms are lined up in chains along the [130] direction, plays important roles in various electron transport phenomena.

  5. Fe-based bulk metallic glasses with a larger supercooled liquid region and high ductility

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, K.Q. [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110178 (China)], E-mail: kqqiu@yahoo.com.cn; Pang, J.; Ren, Y.L.; Zhang, H.B. [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110178 (China); Ma, C.L.; Zhang, T. [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)

    2008-12-20

    Bulk metallic glasses (BMGs) with compositions of Fe{sub 61.5-x}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}M{sub x} (x = 2, 3; M = Ni, Nb) were fabricated by copper mold casting using raw industrial materials. The X-ray diffraction (XRD), differential scanning calorimetry (DSC), mechanical tester and scanning electron microscope (SEM) were employed to check the phase constituent, the thermal stability, the mechanical properties and the fracture surfaces of as-cast samples. The results indicate that the BMGs with diameters of 1.5-3 mm were fabricated for the alloys investigated. The largest supercooled liquid region (SLR) up to 76 K was found for Fe{sub 58.5}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}Ni{sub 3} BMG. The BMGs with Ni addition exhibit not only high fracture strengths reaching 3770 MPa for x = 2 and 3980 MPa for x = 3 alloys, respectively, but also apparently plastic strains up to 0.67% and 0.93%, respectively. The fracture surfaces of the Fe{sub 61.5-x}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}Ni{sub x} (x = 2, 3) alloys with plasticity show narrow ridges characteristic of venous patterns combining with tearing flow between the ridges. While the Nb containing alloys show not only a lower SLR below 60 K but also a lower stress below 2400 MPa, as well as almost no plastic strain before fracture.

  6. Analysis of sodium metal by X-ray fluorescence spectrometry (I). Determination of Hf, Mo, Nb, Ta, Ti, V and Zr; Analisis de sodio metal por espectrometria de fluorescencia de rayos X. Determinacion de Hf, Mo, Nb, Ta, Ti, V y Zr

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Guerra, J P

    1981-07-01

    A method allowing the determination of trace quantities of Hf, Mo, Nb, Ta, Ti, Vi and Zr in sodium metal previous transformation into Na{sub 2}S0{sub 4} is described. The enrichment of the impurities is performed through a coprecipitation technique in sulfuric medium by using Fe{sup 3}+ as a collector and cupferron or phenyfluorone as the precipitating reagent. The matrix influence and the best concentration of the collector (10/{mu}/ml), adequate pH (1,3 or 4, respectively) and optimum filter type (Millipore BSWP02500 or BDWP04700, respectively) have been studied, as well as the precipitation recoveries corresponding to the reagent above. It has been demonstrated the batter efficiency of the cupferron for determining all the Impurities. Detection limits range from 0.01 to 0.2 ppm., depending on the element, for samples 4 g in weight. An automatic spectrometer attached to a 16 K minicomputer and X-ray tube with a gold anode (2250-2700 W) are used. The Interferences between the lines ZrK{alpha} (2{sup n}d order) - HfL{alpha} and TiK{beta} - VK {alpha} have been studied and the respective correction coefficients have been deduced. (Author) 8 refs.

  7. Influence of AC external magnetic field perturbation on the guidance force of HTS bulk over a NdFeB guideway

    International Nuclear Information System (INIS)

    Zhang Longcai; Wang Jiasu; Wang Suyu; He Qingyong

    2007-01-01

    Superconducting maglev vehicle system requires that the surface magnetic field of the guideway is uniform along the forward direction. But in practice the surface magnetic field of the NdFeB permanent magnet guideway is not always immutable. So the HTS bulks in this case are exposed to AC external magnetic field, which may induce the energy loss in the bulk and influence the guidance force between the HTS bulks and the NdFeB guideway. In this paper, we experimentally studied the influence of the AC external magnetic field perturbation on the guidance force of a HTS bulk over the NdFeB guideway. The experimental results showed that the guidance force was influenced by the application of the AC external magnetic. The guidance fore hysteresis became more evident with the amplitude of the AC field and was independent of the frequency in the range 90-400 Hz. We attributed the reason to magnetic hysteresis loss in the superconductor

  8. Influence of AC external magnetic field perturbation on the guidance force of HTS bulk over a NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China)]. E-mail: zhlcai2000@163.com; Wang Jiasu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China); Wang Suyu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China); He Qingyong [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu, Sichuan 610031 (China)

    2007-08-01

    Superconducting maglev vehicle system requires that the surface magnetic field of the guideway is uniform along the forward direction. But in practice the surface magnetic field of the NdFeB permanent magnet guideway is not always immutable. So the HTS bulks in this case are exposed to AC external magnetic field, which may induce the energy loss in the bulk and influence the guidance force between the HTS bulks and the NdFeB guideway. In this paper, we experimentally studied the influence of the AC external magnetic field perturbation on the guidance force of a HTS bulk over the NdFeB guideway. The experimental results showed that the guidance force was influenced by the application of the AC external magnetic. The guidance fore hysteresis became more evident with the amplitude of the AC field and was independent of the frequency in the range 90-400 Hz. We attributed the reason to magnetic hysteresis loss in the superconductor.

  9. Structural Relaxation in Fe78Nb2B20 Amorphous Alloy Studied by Moessbauer Spectroscopy

    International Nuclear Information System (INIS)

    Kansy, J.; Hanc, A.; Rasek, J.; Haneczok, G.; Pajak, L.; Stoklosa, Z.; Kwapulinski, P.

    2011-01-01

    It was shown that soft magnetic properties of Fe 78 Nb 2 B 20 amorphous alloy can be significantly improved by applying 1-h annealing at temperature 623 K (permeability increases even about 8 times). The Moessbauer Spectroscopy technique indicated that the optimized microstructure (corresponding to the maximum magnetic permeability) is free of iron nanograins and should be attributed to annealing out of free volume and a reduction of internal stresses i.e. to the relaxed amorphous phase. (authors)

  10. Evaluation the homogenisation behaviour of Sm-Fe-Nb materials by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sinan, S. A.; Muryaed, Y.; Alhweg, F. A.

    2004-01-01

    The microstructure of cast and annealed Sm-Fe-Nb materials were investigated by Moessbauer spectroscopy. The aim of the present work is to study the effect of Nb additions upon the microstructure of Sm 2 Fe 17 material and evaluation the homogenisation behaviour of different Sm-Fe-Nb materials. The niobium free cast material consisting of the Sm 2 Fe 17 phase and significant amounts of the free iron (α -Fe). Therefore, the homogenisation process is necessary to eliminate the free iron and produce a single Sm 2 Fe 17 phase material. This process takes long annealing time, up to seven days. The Sm 9 .5 Fe 8 7.5 Nb 3 alloy contains the lowest amount of α-Fe among, the Sm-Fe-Nb materials. Thus the homogenisation step was carried out with treatment time (12 hours) smaller than the reported annealing time of Nb-free material (Sm 2 Fe 17 ). Therefore, the addition of at 3% Nb reduces the manufacturing cost of the Sm 2 Fe 17 and makes this based material for permanent magnets, more industrially desirable, due to elimination the free iron with lowest treatment time. Also it was found that the existence of the paramagnetic NbFe 2 phase becomes higher after the homogenisation process, which can be explained due to the diffusion of Nb from Sm 2 Fe 17 phase to paramagnetic NbFe 2 phase, during the annealing process. (authors)

  11. High sensitivity zero-biased magnetic field sensor based on multiphase laminate heterostructures with FeCuNbSiB nanocrystalline soft magnetic alloy

    Science.gov (United States)

    Qiu, Jing; Wen, Yumei; Li, Ping; Chen, Hengjia

    2016-05-01

    In this paper, a high sensitivity zero-biased magnetic field sensor based on multiphase laminate heterostructures consisting of FeCuNbSiB/Terfenol-D (Tb1-xDyxFe2)/PZT (Pb(Zr1-x,Tix)O3)/Terfenol-D/PZT/Ternol-D/FeCuNbSiB (FMPMPMF) is presented, whose ME coupling characteristics and sensing performances have been investigated. Compared to traditional Terfenol-D/PZT/Terfenol-D (MPM) and Terfenol-D/PZT/Terfenol-D/PZT/Terfenol-D (MPMPM) sensors, the zero-biased ME coupling characteristics of FMPMPMF sensor were significantly improved, owing to a build-in magnetic field in FeCuNbSiB/Terfenol-D layers. The optimum zero-biased resonant ME voltage coefficient of 3.02 V/Oe is achieved, which is 1.65 times as great as that of MPMPM and 2.51 times of MPM sensors. The mean value of low-frequency ME field coefficient of FMPMPMF reaches 122.53 mV/cm Oe, which is 2.39 times as great as that of MPMPM and 1.79 times of MPM sensors. Meanwhile, the induced zero-biased ME voltage of FMPMPMF sensor shows an excellent linear relationship to ac magnetic field both at the low frequency (1 kHz) and the resonant frequency (106.6 kHz). Remarkably, it indicates that the proposed zero-biased magnetic field sensor give the prospect of being able to applied to the field of highly sensitive ac magnetic field sensing.

  12. Some new experimental results on the Zr-Nb-Fe system

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C. [Departamento de Fisica - CAC - Comision Nacional de Energia Atomica, Av. Gral Paz 1499, (1650) San Martin, Buenos Aires (Argentina)]. E-mail: ciramos@cnea.gov.ar; Saragovi, C. [Departamento de Fisica - CAC - Comision Nacional de Energia Atomica, Av. Gral Paz 1499, (1650) San Martin, Buenos Aires (Argentina); Granovsky, M.S. [Departamento de Materiales - CAC - Comision Nacional de Energia Atomica, Av. Gral Paz 1499, (1650) San Martin, Buenos Aires (Argentina)

    2007-06-30

    The scope of this study is the identification and characterization of intermetallic phases and their binary and ternary fields in the Zr-Nb-Fe phase diagram. A construction of the central region of the phase diagram at 900 {sup o}C was proposed using new experimental results obtained by optical and scanning electron microscopies, X-ray diffraction and microprobe analysis. In addition to the well-known Laves C15-type (ZrNb)Fe{sub 2} phase (the polytypic C14 and C36 structures were not detected in the studied compositions), another Laves C14-type phase was found (Zr(NbFe){sub 2}). Watson and Bennett maps helped to predict the occurrence of both of these phases. Moreover, the validity of the Pettifor prediction model for Laves phases in pseudobinary systems with transition elements was checked, verifying the obtained experimental results in the Zr-Nb-Fe system. On the other hand it was determined that the Zr-Nb-Fe ternary system at 900 {sup o}C, as it happens in the binary Zr-Nb system, would have a miscibility gap ({beta}-Zr + {beta}-Nb) in the 25-70 at.% Nb composition range, accepting up to 3 at.% Fe approximately.

  13. Nuclear Magnetic Resonance (NMR) study of the nanocrystalline alloy Fe73.5 Cu1 Nb3 Si13.5 B9

    International Nuclear Information System (INIS)

    Aliaga-Guerra, D.; Iannarella, L.; Fontes, M.B.; Guimaraes, A.P.; Skorvanek, I.

    1994-05-01

    Nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloys were studied with spin echo NMR at 4.2 K, from 15 to 100 MHz. Several lines are observed, with signals from domains and domain walls. Signals at 50-90 MHz appear to arise from 93 Nb nuclei in the amorphous matrix and in the interface of the crystallites. (author). 5 refs, 3 figs

  14. Isotropic and anisotropic nanocrystalline NdFeB bulk magnets prepared by binder-free high-velocity compaction technique

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xiangxing [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Zhongwu, E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Hongya [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Xiao, Zhiyu [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang, Guoqing [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China)

    2015-09-15

    NdFeB powders were consolidated into nanocrystalline bulk magnets by a near-net-shape process of high-velocity compaction (HVC) at room temperature with no binder employed. The nanostructure can be maintained after compaction. The compacted magnets with relatively high density can inherit the coercivity of the starting powders. The mechanical strength of the HVCed magnet after heat treatment is comparable to that of the conventional bonded NdFeB magnets. The anisotropic magnet has also been prepared by hot deformation using HVCed magnet as the precursor. The remanence value along the pressing direction increased from 0.64 to 0.95 T and maximum energy product (BH){sub max} increased from 65 to 120 kJ/m{sup 3} after hot deformation. The processing–structure–properties relationships for both isotropic and anisotropic magnets are discussed. - Highlights: • HVC is a feasible binder-free approach for preparing NdFeB magnets. • The compacted magnets can inherit the coercivity of the starting powders. • The magnets post heat treatment have compression strength higher than bonded magnets. • The approach of HVC is a potential pre-process for anisotropic NdFeB bulk magnets.

  15. Isotropic and anisotropic nanocrystalline NdFeB bulk magnets prepared by binder-free high-velocity compaction technique

    International Nuclear Information System (INIS)

    Deng, Xiangxing; Liu, Zhongwu; Yu, Hongya; Xiao, Zhiyu; Zhang, Guoqing

    2015-01-01

    NdFeB powders were consolidated into nanocrystalline bulk magnets by a near-net-shape process of high-velocity compaction (HVC) at room temperature with no binder employed. The nanostructure can be maintained after compaction. The compacted magnets with relatively high density can inherit the coercivity of the starting powders. The mechanical strength of the HVCed magnet after heat treatment is comparable to that of the conventional bonded NdFeB magnets. The anisotropic magnet has also been prepared by hot deformation using HVCed magnet as the precursor. The remanence value along the pressing direction increased from 0.64 to 0.95 T and maximum energy product (BH) max increased from 65 to 120 kJ/m 3 after hot deformation. The processing–structure–properties relationships for both isotropic and anisotropic magnets are discussed. - Highlights: • HVC is a feasible binder-free approach for preparing NdFeB magnets. • The compacted magnets can inherit the coercivity of the starting powders. • The magnets post heat treatment have compression strength higher than bonded magnets. • The approach of HVC is a potential pre-process for anisotropic NdFeB bulk magnets

  16. Anomalous grain growth in nanocrystalline Fe73.5Cu1Nb3Su13.5B9 alloys

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    1997-01-01

    The grain growth of the FeSi phase during the crystallization process of the amorphous Fe73.5Cu1Nb3Si13.5B9 alloy was studied using transmission electron microscopy and x-ray diffractometry. An anomalous grain growth behaviour of the FeSi phase in the samples annealed in temperature range from 743...... to 823 K for one hour was observed, i.e. the grain size of the FeSi phase slightly decreases when the annealing temperature increases from 743 K ot 823 K. The mechanism of the anomalous grain growth may be due to the different nucleation and volume diffusion rates in the samples anneales at low and high...

  17. Similar and dissimilar friction welding of Zr-Cu-Al bulk glassy alloys

    International Nuclear Information System (INIS)

    Shin, Hyung-Seop; Park, Jung-Soo; Jung, Yoon-Chul; Ahn, Jung-Ho; Yokoyama, Yoshihiko; Inoue, Akihisa

    2009-01-01

    The friction welding of three kinds of Zr-Cu-Al bulk glassy alloys (BGAs) which show eutectic or hypoeutectic compositions to similar and dissimilar BGAs and crystalline metals has been tried. The shape and volume of the protrusion formed at the weld interface were investigated. In order to characterize the friction welded interface, micrographic observation and X-ray diffraction analysis on the weld cross-section were carried out. A successful joining of Zr-Cu-Al bulk glassy alloys to similar and dissimilar BGAs was achieved without occurrence of crystallizations at the weld interface through the precise control of friction conditions. In addition, the joining of Zr 50 Cu 40 Al 10 BGA to crystalline alloys was tried, but it was only successful for specific material combinations. The residual strength after welding of dissimilar BGAs was evaluated by the four-point bending test.

  18. Ferromagnetic characteristics of HfFe2

    International Nuclear Information System (INIS)

    Novakovic, N.; Belosevic-Cavor, J.; Cekic, B.; Manasijevic, M.; Milosevic, Z. . E-mail address of correspoding author: novnik@rt270.vin.bg.ac.yu; Novakovic, N.)

    2003-01-01

    The magnetic hyperfine fields at 181 Ta ion-probe sites in the HfFe 2 polycrystalline binary compound were measured using the time-differential perturbed angular correlation (TDPAC) method. Measurements were performed in the absence of polarizing external magnetic field, at room temperature. The existence of two different structures, dominant cubic MgCu 2 -type and hexagonal MgZn 2 -type in our HfFe 2 sample was refined. Both structures are ferromagnetic with Curie temperatures, which differ significantly (588 K for MgCu 2 and 427 K for MgZn 2 ). The corresponding values of hyperfine fields are H hf 13.8±0.1 T for MgCu 2 -type structure and H hf = 8.0±0.2 T for MgZn 2 -type structure. Calculations using LAPW-Wien 97 program package are in progress and preliminary results are in good agreement with experiment. The analysis includes qualitative explanation of the exchange interactions mechanism between magnetic dipole moment of the observed 181 Ta ion-probe and magnetic dipole moments of the nearest neighbours on the corresponding coordination polyhedra. All these results will be published recently. (author)

  19. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: zhlcai2000@163.com; Wang Suyu; Wang Jiasu; Zheng Jun [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  20. Creep properties of annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe cladding tubes and their performance comparison

    International Nuclear Information System (INIS)

    Ko, S.; Hong, S.I.; Kim, K.T.

    2010-01-01

    Creep properties of annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe cladding tubes were studied and compared. The creep rates of the annealed Zr-Nb-O alloy were found to be greater than those of the stress-relieved Zr-Nb-Sn-Fe alloy. Zr-Nb-O alloy was found to have stress exponents of 5-7 independent of stress level whereas Zr-Nb-Sn-Fe alloy exhibited the transition of the stress exponent from 6.5 to 7.5 in the lower stress region to ∼4.2 in the higher stress region. The reduction of stress exponent at high stresses in Zr-Nb-Sn-Fe can be explained in terms of the dynamic solute-dislocation effect caused by Sn atoms. The constancy of stress exponent without the transition was observed in Zr-Nb-O alloy, supporting that the decrease of the stress exponent with increasing stress in Zr-Nb-Sn-Fe is associated with Sn atoms. The difference of creep life between annealed Zr-Nb-O and stress-relieved Zr-Nb-Sn-Fe is not large considering the large difference of strength level between annealed Zr-Nb-O and annealed stress-relieved Zr-Nb-Sn-Fe. The better-than-expected creep life of annealed Zr-Nb-O alloy can be attributable to the combined effects of creep ductility enhancement associated with softening and the decreased contribution of grain boundary diffusion due to the increased grain size.

  1. A new type of Nb (Ta)-Zr(Hf)-REE-Ga polymetallic deposit in the late Permian coal-bearing strata, eastern Yunnan, southwestern China: Possible economic significance and genetic implications

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Shifeng; Wang, Xibo; Luo, Yangbing; Song, Zhentao; Ren, Deyi [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083 (China); Zhou, Yiping; Zhang, Mingquan; Wang, Jumin; Song, Xiaolin; Yang, Zong [Yunnan Institute of Coal Geology Prospection, Kunming 650218 (China); Jiang, Yaofa [Xuzhou Institute of Architectural Technology, Xuzhou 221116 (China)

    2010-07-01

    This paper describes a new type of Nb(Ta)-Zr(Hf)-REE-Ga polymetallic deposit of volcanic origin in the late Permian coal-bearing strata of eastern Yunnan, southwestern China. Well logging data (especially natural gamma-ray), geochemical data (high concentrations of Nb, Ta, Zr, Hf, REE, and Ga) and mineralogical compositions (Nb(Ta)-, Zr(Hf)-, or REE-bearing minerals rarely observed), together with the volcanic lithological characteristics indicate that there are thick (1-10 m, mostly 2-5 m) ore beds in the lower Xuanwei Formation (late Permian) in eastern Yunann of southwestern China. The ore beds are highly enriched in (Nb,Ta){sub 2}O{sub 5} (302-627 ppm), (Zr,Hf)O{sub 2} (3805-8468 ppm), REE (oxides of La-Lu + Y) (1216-1358 ppm), and Ga (52.4-81.3 ppm). The ore beds are mainly composed of quartz, mixed-layer illite-smectite, kaolinite, berthierine, and albite. Four types of ore beds in the study area were identified, namely, clay altered volcanic ash, tuffaceous clay, tuff, and volcanic breccia. Preliminary studies suggest that the high concentrations of otherwise rare metals were mainly derived from the alkalic pyroclastic rocks. The modes of occurrence, spatial distribution, and enrichment mechanism of the rare metals, however, require further study. (author)

  2. Influence of annealing on structure and magnetic properties of Laves phase HfFe2

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Cekic, B.; Novakovic, N.; Ivanovic, N.; Manasijevic, M.

    2004-01-01

    Hyperfine fields (HFF) in a polycrystalline HfFe 2 binary compound were measured at 181 Ta probe ion sites using the time differential perturbed angular correlation (TDPAC) method. Analysis of TDPAC spectra obtained in measurements revealed two components. One of them corresponded to the magnetic perturbation with the value B hf1 (Ta) = 13.82(7) T at room temperature and it was ascribed to the interaction at the regular position of Hf in the cubic C15 (MgCu 2 -type) structure of the HfFe 2 compound. The second component with hyperfine field value of B hf2 (Ta) = 8.0(2) T is probably due to the presence of a minor amount of the hexagonal C14 (MgZn 2 -type) structure. Measurements showed that it had come to a change in the ratio of different components of TDPAC spectra with annealing, but the values for hyperfine fields for both components have not changed significantly. The origin of the hyperfine magnetic field and its difference in the two structures (C14 and C15) were discussed taking into account crystal structure effects. (orig.)

  3. 57Fe Moessbauer study of amorphous and nanocrystalline Fe73.5Nb3Cu1Si13.5B9 after neutron irradiation

    International Nuclear Information System (INIS)

    Miglierini, M.; Sitek, J.; Szasz, Z.; Vitazek, K.

    1994-01-01

    57 Fe Moessbauer spectroscopy is used to study neutron irradiation induced changes in the short-range order of Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 alloy. The samples are investigated in both amorphous and nanocrystalline states. Neutron irradiation leads to an increase of the standard deviation of a hyperfine field distribution (HFD), implying rearrangement of the atoms towards disordering. Simultaneously, changes in the average value of the hyperfine field and a net magnetic moment position occur as a consequence of a spin reorientation, atom mixing and microscopic stress centres which are introduced by neutron irradiation. (orig.)

  4. Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

    Science.gov (United States)

    Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

    2012-06-01

    Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

  5. On the stabilization of NbV-solutions by ZrIV and HfIV

    International Nuclear Information System (INIS)

    Soerensen, E.; Bjerre, A.B.

    1987-11-01

    Niobium cannot be separated from zirconium or hafnium when these elements occur together in solution with common anions such as Cl- and SO 4 --. This is ascribed to the copolymerisation of Nb v and the hydrolyzed ionic species of Zr IV v and Hf IV by which the colloidal particles are masked as Zr- and Hf-compounds. In HCl the particles are positively charged as opposed to when they are in sulphate solution where the Zr- and Hf- sulphate complexes confer a negative charge. The two cases are considered separately. (author)

  6. Low electron density of states at the boron site of TMB{sub 2} (TM = Ti, Zr, Hf, and Nb): a {sup 11}B NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, S.; Zogal, O.J.; Peshev, P

    2004-11-30

    The local density of states at the boron site in TMB{sub 2} (TM=Ti, Zr, Hf, and Nb) has been examined using the solid-state {sup 11}B NMR technique. The magic angle spinning (MAS) NMR spectra at room temperature and the spin-lattice relaxation rates have been measured as functions of temperature (30-293 K). The resonance line shifts are small and become more negative in the direction from 3d- to 5d-elements. The relaxation rates follow a linear law characteristic of hyperfine magnetic interaction with conduction electrons. With borides of IV group metals the data can be understood in terms of a very low s-electron density of states and absence of a p-character of the conduction electron wave function at the Fermi level while in the case of NbB{sub 2} a small partial p-electron density of states is assumed. Then, the results are in good agreement with the earlier theoretical prediction.

  7. Study of the influence of the temperature in the magnetic properties and in microstructure in the permanent magnets Pr-Fe-B-Nb-Co based obtained by hydrogen; Estudo da influencia da temperatura nas propriedades magneticas e na microestrutura nos imas permanentes a base de Pr-Fe-B-Nb-Co obtidos com hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Suelanny Carvalho da

    2007-07-01

    Fine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900 deg C with the purpose of optimizing the HDDR treatment for Pr{sub 14}Fe{sub 80}B{sub 6} and Pr{sub 14}Fe{sub bal}Co{sub x}B{sub 6}Nb{sub 0,1} (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100 deg C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880 deg C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840 deg C and 820 deg C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840 deg C. The optimum desorption temperature for achieving high anisotropy for Pr{sub 14}Fe{sub 80}B{sub 6} and Pr{sub 14}Fe{sub 79,9}B{sub 6}Nb{sub 0,1} was 820 deg C. The best remanence (862 mT) was achieved with the Pr{sub 14}Fe{sub 67,9}B{sub 6}Co{sub 12}Nb{sub 0,1} magnet, processed at 840 deg C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr{sub 14}Fe{sub 80}B{sub 6} HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy has also been employed to reveal the morphology of the HDDR powder. (author)

  8. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weiming [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Sun, Baoan [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Zhao, Yucheng, E-mail: zhaoyc1972@163.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Li, Qiang [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Hou, Long; Luo, Ning [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Dun, Chaochao [Department of Physics, Wake Forest University, Winston Salem, NC 27109 (United States); Zhao, Chengliang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Ma, Zhanguo [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Shen, Baolong [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-08-15

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  9. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Yang, Weiming; Sun, Baoan; Zhao, Yucheng; Li, Qiang; Hou, Long; Luo, Ning; Dun, Chaochao; Zhao, Chengliang; Ma, Zhanguo; Liu, Haishun; Shen, Baolong

    2016-01-01

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe_5_0Ni_3_0P_1_3C_7 glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe_5_0Ni_3_0P_1_3C_7 metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  10. Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb2MB2 (M=Fe, Ru, Os) from first principles calculations

    International Nuclear Information System (INIS)

    Touzani, Rachid St.; Fokwa, Boniface P.T.

    2014-01-01

    The Nb 2 FeB 2 phase (U 3 Si 2 -type, space group P4/mbm, no. 127) is known for almost 50 years, but until now its magnetic properties have not been investigated. While the synthesis of Nb 2 OsB 2 (space group P4/mnc, no. 128, a twofold superstructure of U 3 Si 2 -type) with distorted Nb-layers and Os 2 -dumbbells was recently achieved, “Nb 2 RuB 2 ” is still not synthesized and its crystal structure is yet to be revealed. Our first principles density functional theory (DFT) calculations have confirmed not only the experimental structures of Nb 2 FeB 2 and Nb 2 OsB 2 , but also predict “Nb 2 RuB 2 ” to crystalize with the Nb 2 OsB 2 structure type. According to chemical bonding analysis, the homoatomic B–B interactions are optimized and very strong, but relatively strong heteroatomic M–B, B–Nb and M–Nb bonds (M=Fe, Ru, Os) are also found. These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of these ternary borides. The density-of-states at the Fermi level predicts metallic behavior, as expected, from metal-rich borides. Analysis of possible magnetic structures concluded preferred antiferromagnetic ordering for Nb 2 FeB 2 , originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them. -- Graphical abstract: Nb 2 FeB 2 (U 3 Si 2 structure type, space group P4/mbm, no. 127) is predicted to order antiferromagnetically, due to the presence of iron chains which show ferromagnetic interactions in the chains and antiferromagnetic interactions between them. “Nb 2 RuB 2 ” is predicted to crystallize with the recently discovered Nb 2 OsB 2 twofold superstructure (space group P4/mnc, no. 128) of U 3 Si 2 structure type. The building of ruthenium dumbbells instead of chains along [001] is found to be responsible for the stabilization of this superstructure. Highlights: • Nb 2 FeB 2 is predicted to order antiferromagnetically.

  11. Energy for the interface system of (Nb, Mo)C/γ-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yanyuan; Wang, Zhenqiang; Zhao, Jiaying; Niu, Zhongyi; Guo, Chunhuan; Jiang, Fengchun [Harbin Engineering University, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin (China); Leng, Zhe [Harbin Engineering University, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin (China); Zhejiang Ocean University, Innovation and Application Institute, Zhoushan (China); Zhang, Zhengyan; Yao, Chunfa [Central Iron and Steel Research Institute, Department of Structural Steels, Beijing (China); Yang, Zhigang [Tsinghua University, Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Beijing (China)

    2017-08-15

    The interfacial energies of MC/γ-Fe and formation energies of MC carbides have been investigated using first-principles calculations based on density functional theory (DFT). Results show that the replacement of Nb by Mo in the NbC lattice is unfavorable with respect to the formation energy. However, it reduces the lattice parameter of MC and decreases the σ{sub chemical} (interfacial chemical energy) of MC/γ-Fe, thus favoring the formation of complex (Nb, Mo)C carbide. The substitution of Nb by Mo at the interface of MC/γ-Fe system promotes the hybridizations of Mo-1NNFe and C-1NNFe (or 2NNFe) (the first or second nearest neighboring Fe atoms), which leads to a decrease in σ{sub chemical}. The influence of bond energy is estimated using the discrete lattice plane/nearest neighbor broken bond (DLP/NNBB) model. It is found that the reduced is attributed to the much smaller value of e{sub Fe-C}-e{sub Mo-C} (the difference between Fe-C and Nb-C interactions). The results obtained from the analysis of the precipitates in Nb- and Nb-Mo-bearing steels are in a good agreement with the calculations. (orig.)

  12. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    International Nuclear Information System (INIS)

    Monroy G, F.; Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C.

    2010-01-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH 4 F/HClO 4 medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K d obtained at different F - and H + concentrations. The anionic complexes: [Zr(Hf)F 5 ] - , [Zr(Hf)F 6 ] 2- , [Zr(Hf)F 7 ] 3- , [Ta(Pa)F 6 ] - , [Ta(Pa)F 7 ] 2- , [Ta(Pa)F 8 ] 3- , [NbOF 4 ] - and [NbOF 5 ] 2- are present as predominant species in the HF range over investigation. (Author)

  13. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  14. Synthesis and devitrification of high glass-forming ability bulk metallic glasses.

    OpenAIRE

    Huang, Hong.

    2007-01-01

    In this thesis, literature on the production, microstructures and properties of bulk metallic glasses (BMG) has been reviewed with particular reference to glass forming ability (GFA) and alloys of the Fe-Zr-B and Zr-based BMG systems. The experimental procedures used in the research are presented and the results for the amorphous Fe80Zr12B8 ribbon and the Zr57Ti5Al10Cu20Ni8, Zr57Nb5Al10Cu20Ni8, Zr53Nb2Al8Cu30Ni7 BMGs are given and discussed. Wedge-shaped ingots of the Zr-based BMGs were produ...

  15. Effects of Nb content on the Zr2Fe intermetallic stability

    International Nuclear Information System (INIS)

    Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

    2003-01-01

    With the aim of studying the stability range of the Zr 2 Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase (λ 1 ) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr 2 Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr 2 Fe+λ 1 region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed

  16. Amorphous and nanocrystalline fraction calculus for the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Muraca, D. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Moya, J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina); Cremaschi, V.J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina) and Carrera del Investigador, CONICET (Argentina)]. E-mail: vcremas@fi.uba.ar; Sirkin, H.R.M. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina)

    2007-09-01

    We studied the relationship between the saturation magnetization (M {sub S}) of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy and its nanocrystalline structure. Amorphous ribbons obtained by the melt spinning technique were heat-treated for 1 h at different temperatures. The optimal treatment to obtain a homogeneous structure of Fe{sub 3}(Si,Ge) nanocrystals with a grain size of around 10 nm embedded in an amorphous matrix involved heating at 540 C for 1 h. We calculated the magnetic contribution of the nanocrystals to the heat treated alloy using a linear model and measured the M {sub S} of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} nanocrystalline and of an amorphous alloy of the same composition of the amorphous matrix: Fe{sub 58}Si{sub 0.5}Ge{sub 3.5}Cu{sub 3}Nb{sub 9}B{sub 26}. Using experimental data and theoretical calculations, we obtained the amorphous and crystalline fraction of the heat-treated ribbons.

  17. Rotating speed effect on electronic transport behaviors of Ni–Nb–Zr–H glassy alloys

    International Nuclear Information System (INIS)

    Fukuhara, Mikio

    2012-01-01

    Highlights: ► The electronic transport behaviors of (Ni 0.39 Nb 0.25 Zr 0.35 ) 100−y H y (0 ≤ y ≤ 15) glassy alloys, which produced by rotating (or quenching) speeds of 3000 and 10,000 rpm, have been studied as a function of hydrogen content. ► The resistivity for (Ni 0.39 Nb 0.25 Zr 0.35 ) 97.8 H 2.2 alloy, produced by rotating speed of 10,000 rpm, displayed 0.1 nΩ cm, which is 0.01% of silver (1.62 μΩ cm) at room temperature, between 40 and 252 K. ► Supercooling of the molten alloy induces a superior ballistic conductor and a room-temperature Coulomb oscillation. - Abstract: The electronic transport behaviors of (Ni 0.39 Nb 0.25 Zr 0.35 ) 100−y H y (0 ≤ y ≤ 15) glassy alloys, produced by rotating (or quenching) speeds of 3000 and 10,000 rpm, have been studied as a function of hydrogen content. These alloys show semiconducting, superior ballistic transport, superconducting and electric current-induced Coulomb oscillation, as hydrogen content increases. The resistivity for (Ni 0.39 Nb 0.25 Zr 0.35 ) 97.8 H 2.2 alloy, produced by rotating speed of 10,000 rpm, displayed 0.1 nΩ cm, which is 0.01% of silver (1.62 μΩ cm) at room temperature, between 40 and 252 K. The Coulomb oscillation of the 10,000 rpm-(Ni 0.39 Nb 0.25 Zr 0.35 ) 95.2 H 4.8 alloy is about 4-fold larger than that of the 3000 rpm-(Ni 0.39 Nb 0.25 Zr 0.35 ) 91.1 H 8.9 alloy. Supercooling of the molten alloy induces a superior ballistic conductor and a room-temperature Coulomb oscillation at lower and higher hydrogen contents, respectively.

  18. Crystallographic alignment in the recombination stage in d-HDDR process of Nd-Fe-B-Ga-Nb powders

    Directory of Open Access Journals (Sweden)

    Takashi Horikawa

    2016-05-01

    Full Text Available Nd-Fe-B-Ga-Nb magnetic powder was subjected to the dynamic hydrogen disproportionation desorption recombination treatment. For samples disproportionated at both 30 and 100 kPa of hydrogen pressure, the changes in the microstructure and grain orientation during recombination process were investigated. It was observed that even during the recombination process, the orientation relationship was maintained between α-Fe and NdH2+x grains formed after the disproportionation treatment at 30 kPa of hydrogen pressure, [110]α-Fe // [110]NdH2+x, (-110α-Fe // (-220NdH2+x. Additionally, the alignment of recombined Nd2Fe14BHy grains became clear after 30 min of DR treatment showing following orientation relationship: (001Nd2Fe14BHy // (110α-Fe and (110NdH2+x. In contrast, such a relationship was not observed in the sample disproportionated at 100 kPa of hydrogen pressure. This difference in the degree of alignment was also confirmed by measuring the magnetic property of the respective samples.

  19. Structural, magnetic and optical properties of Y bFe2O4 films deposited by spin coating

    Directory of Open Access Journals (Sweden)

    Tatsuo Fujii

    2016-08-01

    Full Text Available Rare-earth iron oxides (RFe2O4 have attracting attention as new electronic device materials because of their numerous functionalities, such as electronic ferroelectricity, ferrimagnetism, and high infrared absorption. In this paper, nearly monophasic Y bFe2O4 films were prepared on α-Al2O3(001 substrates by the spin coating method using an aqueous-based Y bFe2O4 solution. The solution was composed of a stoichiometric ratio of Y b(CH3COO3 and Fe(NO33 with excess chelating agents. After heat treatment above 800 °C, well-crystallized and highly (001-oriented Y bFe2O4 started to epitaxially form on the substrate under controlled oxygen partial pressure with H2/CO2 gas mixtures. X-ray pole figure analysis confirmed the following epitaxial relationship: Y bFe2O4[100](001//α-Al2O3[100](001. Moreover formation of an Fe3O4 interracial layer between Y bFe2O4 and α-Al2O3 was detected by high-resolution transmission electron microscopy. Presence of the Fe3O4 interracial layer seemed to release the lattice misfit with the substrate. The Fe2+/Fe3+ ratio in the obtained Y bFe2O4 films was nearly stoichiometric and the indirect bandgap assigned to Fe2+ → Fe3+ charge transfer excitation was found to be ∼0.4 eV by optical spectroscopy. A clear magnetic transition from the paramagnetic state to the ferrimagnetic state occurred at ∼230 K.

  20. Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

    International Nuclear Information System (INIS)

    Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching; Lee, Chih-Jhan; Ho, Wen-Fu

    2010-01-01

    In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable β phase began. However, when 4 mass% Fe or greater was added, the β phase was entirely retained with a bcc crystal structure. Moreover, the ω phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of ω phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9 o ) and Ti-5Nb-5Fe (29.5 o ) alloys were greater than that of c.p. Ti (2.7 o ) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

  1. Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching [Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung 40605, Taiwan (China); Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Changhua 51591, Taiwan (China); Lee, Chih-Jhan [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Ho, Wen-Fu, E-mail: fujii@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China)

    2010-09-15

    In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable {beta} phase began. However, when 4 mass% Fe or greater was added, the {beta} phase was entirely retained with a bcc crystal structure. Moreover, the {omega} phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of {omega} phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9{sup o}) and Ti-5Nb-5Fe (29.5{sup o}) alloys were greater than that of c.p. Ti (2.7{sup o}) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

  2. Development of Fe-B Based Bulk Metallic Glasses: Morphology of Residual Phases in Fe50Ni16Mo6B18Zr10 Glass

    Directory of Open Access Journals (Sweden)

    Tiburce A. Aboki

    2013-04-01

    Full Text Available Iron-boron based bulk metallic glasses (BMG development has been initiated using Fe40Ni38Mo4B18 as precursor. Addition of zirconium up to 10 atomic % along with the reduction of Ni proportion improves the glass forming ability (GFA, which is optimum when Ni is suppressed in the alloy. However melting instability occurred during the materials fabrication resulting in the formation of residual crystalline phases closely related to the amorphous phase. Microstructure study shows an evolution from amorphous structure to peculiar acicular structure, particularly for Fe50Ni16Mo6B18Zr10, suggesting the amorphous structure as interconnected atomic sheets like “atomic mille feuilles” whose growth affects the alloys’ GFA.

  3. Pseudobinary glassy compositions (AsSex)1-y(AsTex)y

    International Nuclear Information System (INIS)

    El Mously, M.K.; El Dem, M.B.

    1987-09-01

    The ternery glassy composition of the general formula (AsSe x ) 1-y (AsTe x ) y can be considered as a pseudobinary system at x=1, 3/2 and 5/2 and 0 ≤ y ≤ 1. The results of DTA, electrical conductivity measurements, density of such glasses as well as the X-ray diffraction of the crystallized samples have been used to confirm this point of view and to explain the presence of new phases not shown in the simple binary systems As-Se and As-Te. The possibility of transformation of the glassy network from partially polymerized state MCN (molecular cluster network) to completely polymerized state CRN (continuous random network) by mixing two structural units was also discussed. (author). 12 refs, 7 figs, 2 tabs

  4. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    Energy Technology Data Exchange (ETDEWEB)

    Monroy G, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C., E-mail: fabiola.monroy@inin.gob.m [Institut de Physique Nucleaire, F-91406 Orsay, France (France)

    2010-07-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH{sub 4}F/HClO{sub 4} medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K{sub d} obtained at different F{sup -} and H{sup +} concentrations. The anionic complexes: [Zr(Hf)F{sub 5}]{sup -}, [Zr(Hf)F{sub 6}]{sup 2-}, [Zr(Hf)F{sub 7}]{sup 3-}, [Ta(Pa)F{sub 6}]{sup -}, [Ta(Pa)F{sub 7}]{sup 2-}, [Ta(Pa)F{sub 8}]{sup 3-}, [NbOF{sub 4}]{sup -} and [NbOF{sub 5}]{sup 2-} are present as predominant species in the HF range over investigation. (Author)

  5. Study of the influence of the temperature in the magnetic properties and in microstructure in the permanent magnets Pr-Fe-B-Nb-Co based obtained by hydrogen

    International Nuclear Information System (INIS)

    Silva, Suelanny Carvalho da

    2007-01-01

    Fine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900 deg C with the purpose of optimizing the HDDR treatment for Pr 14 Fe 80 B 6 and Pr 14 Fe bal Co x B 6 Nb 0,1 (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100 deg C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880 deg C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840 deg C and 820 deg C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840 deg C. The optimum desorption temperature for achieving high anisotropy for Pr 14 Fe 80 B 6 and Pr 14 Fe 79,9 B 6 Nb 0,1 was 820 deg C. The best remanence (862 mT) was achieved with the Pr 14 Fe 67,9 B 6 Co 12 Nb 0,1 magnet, processed at 840 deg C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr 14 Fe 80 B 6 HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy has also been employed to reveal the morphology of the HDDR powder. (author)

  6. Homogeneous nucleation limit on the bulk formation of metallic glasses

    International Nuclear Information System (INIS)

    Drehman, A.J.

    1983-01-01

    Glassy Pd 82 Si 18 spheres, of up to 1 mm diameter, were formed in a drop tube filled with He gas. The largest spheres were successfully cooled to a glass using a cooling rate of less than 800 K/sec. Even at this low cooling rate, crystallization (complete or partial) was the result of heterogeneous nucleation at a high temperature, relative to the temperature at which copious homogeneous nucleation would commence. Bulk underscoring experiments demonstrated that this alloy could be cooled to 385 K below its eutectic melting temperature (1083 K) without the occurrence of crystallization. If heterogeneous nucleation can be avoided, it is estimated that a cooling rate of at most 100 K/sec would be required to form this alloy in the glassy state. Ingots of glassy Pd 40 Ni 40 P 20 were formed from the liquid by cooling at a rate of only 1 K/sec. It was found that glassy samples of this alloy could be heated well above the glass transition temperature without the occurrence of rapid divitrification. This is a result due, in part of the low density of pre-existing nuclei, but, more importantly, due to the low homogeneous nucleation rate and the slow crystal growth kinetics. Based on the observed devitrification kinetics, the steady-state homogeneous nucleation rate is approximately 1 nuclei/cm 3 sec at 590 K (the temperature at which the homogeneous nucleation rate is estimated to be a maximum). Two iron-nickel based glass-forming alloys (Fe 40 Ni 40 P 14 B 6 and Fe 40 Ni 40 B 20 , were not successfully formed into glassy spheres, however, microstructural examination indicates that crystallization was not the result of copious homogeneous nucleation. In contrast, glass forming iron based alloys (Fe 80 B 20 and Fe/sub 79.3/B/sub 16.4/Si/sub 4.0/C/sub 0.3/) exhibit copious homogeneous nucleation when cooled at approximately the same rate

  7. Magnetic and structural properties of the Nd2(Fe100-xNbx)14B system prepared by arc melting

    International Nuclear Information System (INIS)

    Oyola Lozano, D.; Zamora, L. E.; Perez Alcazar, G. A.; Rojas, Y. A.; Bustos, H.; Greneche, J. M.

    2006-01-01

    In this work the magnetic and structural properties are investigated by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd 2 (Fe 100-x Nb x ) 14 B powdered alloys with x = 0, 2 and 4 prepared by arc melting. The Moessbauer spectra of the samples were fitted with several contributions from: Nd 2 Fe 14 B, α-Fe and a paramagnetic phase associated with Nd 1.1 Fe 4 B 4 for x = 0 and additionally from NbFeB and Nd 2 Fe 17 for x = 2 and x = 4. The relative fractions of α-Fe and Nd 2 Fe 14 B are smaller for x = 4 than for x = 0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd 2 Fe 17 increases. The α-Fe grain size slightly decreases while that of the Nd 2 Fe 14 B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization.

  8. Structural study of conventional and bulk metallic glasses during annealing

    International Nuclear Information System (INIS)

    Pineda, E.; Hidalgo, I.; Bruna, P.; Pradell, T.; Labrador, A.; Crespo, D.

    2009-01-01

    Metallic glasses with conventional glass-forming ability (Al-Fe-Nd, Fe-Zr-B, Fe-B-Nb compositions) and bulk metallic glasses (Ca-Mg-Cu compositions) were studied by synchrotron X-ray diffraction during annealing throughout glass transition and crystallization temperatures. The analysis of the first diffraction peak position during the annealing process allowed us to follow the free volume change during relaxation and glass transition. The structure factor and the radial distribution function of the glasses were obtained from the X-ray measurements. The structural changes occurred during annealing are analyzed and discussed.

  9. Structure and physical properties of ternary uranium transition-metal antimonides U3MSb5 (M = Zr, Hf, Nb)

    International Nuclear Information System (INIS)

    Tkachuk, Andriy V.; Muirhead, Craig P.T.; Mar, Arthur

    2006-01-01

    The ternary uranium transition-metal antimonides U 3 MSb 5 (M = Zr, Hf, Nb) were prepared by arc-melting reactions followed by annealing at 800 deg. C, or by use of a Sn flux. These compounds extend the previously known series U 3 MSb 5 (M = Ti, V, Cr, Mn) and RE 3 MSb 5 (RE = La, Ce, Pr, Nd, Sm; M = Ti, Zr, Hf, Nb). The crystal structures of U 3 MSb 5 were determined by single-crystal X-ray diffraction data (Pearson symbol hP18, hexagonal, space group P6 3 /mcm, Z = 2; U 3 ZrSb 5 , a = 9.2223(3) A, c = 6.1690(2) A; U 3 HfSb 5 , a = 9.2084(4) A, c = 6.1629(3) A; U 3 NbSb 5 , a = 9.1378(4) A, c 6.0909(6) A). U 3 TaSb 5 has also been identified in microcrystalline form (a = 9.233(3) A, c = 6.142(3) A). Four-probe electrical resistivity measurements on single crystals and dc magnetic susceptibility measurements on powders indicated prominent transitions that are attributed to ferromagnetic ordering. The Curie temperatures, T C , located from ac magnetic susceptibility curves, are 135 K for U 3 ZrSb 5 , 141 K for U 3 HfSb 5 , and 107 K for U 3 NbSb 5

  10. Critical state instability in Nb-clad MgB2 superconducting wires

    International Nuclear Information System (INIS)

    Beilin, V.; Felner, I.; Tsindlekht, M.I.; Dul'kin, E.; Mojaev, E.; Roth, M.

    2008-01-01

    Magnetization hysteresis loops of Cu/MgB 2 , Nb/MgB 2 , Cu/Nb/MgB 2 and Fe/Cu/MgB 2 wires in parallel magnetic fields of up to 5 T were studied in the temperature range from 5 to 35 K. All Nb-clad samples exhibited a thermomagnetic instability (TMI) in the form of magnetization jumps. In a thick wire (about 2 mm in core diameter), the TMI persisted up to the unexpectedly high temperature of 32 K. Thin wires showed low TMI which vanished at T > 10 K. Cu/MgB 2 wires which did not contain a Nb barrier, showed no signs of TMI. The TMI in thin wires exhibited good reproducibility and stability in the jump pattern (JP) (jump amplitudes and positions), while thick wires showed the worst time stability. We found that moderate flat rolling of the round unstable Cu/Nb/MgB 2 wire resulted in negligible TMI at 5 K in the processed flat tape. The TMI amplitudes of studied samples correlated with the adiabatic stability parameter, β -1

  11. Enthalpy of mixing of liquid Cu-Fe-Hf alloys at 1873 K

    Energy Technology Data Exchange (ETDEWEB)

    Agraval, Pavel; Turchanin, Mikhail [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Dreval, Liya [Donbass State Engineering Academy, Kramatorsk (Ukraine). Metallurgical Dept.; Materials Science International Services GmbH (MSI), Stuttgart (Germany)

    2016-12-15

    In the ternary Cu-Fe-Hf system, the mixing enthalpies of liquid alloys were investigated at 1873 K using a high-temperature isoperibolic calorimeter. The experiments were performed along the sections x{sub Cu}/x{sub Fe} = 3/1, 1/1 at x{sub Hf} = 0-0.47 and along the section x{sub Cu}/x{sub Fe} = 1/3 at x{sub Hf} = 0-0.13. The limiting partial enthalpies of mixing of undercooled liquid hafnium in liquid Cu-Fe alloys, Δ{sub mix} anti H{sub Hf}{sup ∞}, are (-122 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 3/1), (-106 ± 9) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/1), and (-105 ± 2) kJ mol{sup -1} (section x{sub Cu}/x{sub Fe} = 1/3). In the investigated composition range, the integral mixing enthalpies are sign-changing. For the integral mixing enthalpy, an analytical expression was obtained by the least squares fit of the experimental results using the Redlich-Kister-Muggianu polynomial.

  12. Crystallization kinetics and magnetic properties of Fe{sub 66}Nb{sub 4}B{sub 30} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, M., E-mail: m.stoica@ifw-dresden.d [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Kumar, S. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Roth, S. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India); Eckert, J. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Vaughan, G. [European Synchrotron Radiation Facilities ESRF, 38402 Grenoble (France); Yavari, A.R. [LTPCM-CNRS, Institut National Politechnique de Grenoble, 1130 Rue de la Piscine, BP 75, Saint Martin d' Heres Campus 38402 (France)

    2009-08-26

    Fe-based bulk metallic glasses (BMGs) have a high application potential because of their unique soft magnetic properties, mechanical behaviour and high corrosion resistance. Also, they can be obtained directly in the final shape suitable for use as magnetic sensors, magnetic valves, magnetic clutches etc. in different devices. Fe-based alloys able to form magnetic BMGs are of the type transition metal-metalloid and often contain 5 or more elements. Usually, the metalloid content is around 20 at.%. Recently, a new Fe-based BMG containing only 3 elements and a very high boron content was synthesized. The preparation of this BMG was done by employing the copper mold casting method and using the fluxing technique. This new BMG is ferromagnetic, with a Curie temperature around 550 K and a saturation magnetization of 105 Am{sup 2}/kg. Differential scanning calorimetry (DSC) investigations revealed a reduced glass transition temperature of 0.55 and an extension of the supercooled liquid region of about 31 K, values which indicate a relatively good thermal stability. Despite of numerous studies about Fe-based BMGs, there is still a lack of data about the crystallization kinetics. Also, the intermediate metastable phases, which form upon crystallization from the amorphous state, as well as the mechanism of their formation, are not fully understood. The present work discusses the kinetics of the phase formation using the Kissinger analysis and Johnson-Mehl-Avrami plots, correlated with the results obtained upon X-ray diffraction (XRD) of samples with different metastable structures. Additionally, the magnetic behaviour of different phase(s) is presented.

  13. Phase stability, crystal structure and magnetism in (U1-xNbx)2 Ni21B6 and (UyNb1-y)3Ni20B6

    Science.gov (United States)

    Provino, Alessia; Bhattacharya, Amitava; Dhar, Sudesh K.; Pani, Marcella; Gatti, Flavio; Paudyal, Durga; Manfrinetti, Pietro

    Ternary phases with composition T2M21X6 and T3M20X6 (T = transition metal; M = 3 d metal; X = B, C, P) are reported to crystallize with the W2Cr21C6-type and Mg3Ni20B6-type, respectively (ternary ordered derivatives of the cubic Cr23C6-type, cF116). They attract interest due to their refractory, mechanical, and peculiar magnetic properties. Literature data on these compounds only concern apparently stoichiometric 2:21:6 and 3:20:6 phases. Often only nominal composition has been reported, with few structural refinements and no measurements of physical properties. Lack of detailed stoichiometry and crystallographic data does not allow sufficient understanding of the crystal chemistry and properties of these compounds. We studied stability, crystal structure and magnetism of (U1-xNbx)2 Ni21B6 and (UyNb1-y)3Ni20B6; stable phases are U2Ni21B6 and Nb3Ni20B6, as also confirmed by theoretical calculations. The two pristine compounds solubilize Nb and U, respectively, up to a given extent. The substitution of U by Nb leads to a structural change from the W2Cr21C6- to the Mg3Ni20B6-type. While U2Ni21B6 is a Pauli paramagnet (itinerant non-magnetic state of U-5 f electrons), in agreement with literature, magnetization data for (UyNb1-y)3 Ni20B6 show itinerant ferromagnetism with TC >300 K.

  14. Enhanced photovoltaic currents in strained Fe-doped LiNbO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Ryotaro [Division of Physics, Institute of Liberal Education, School of Medicine, Nihon University, 31-10, Ooyaguchi-kamicho, Itabashi-ku, Tokyo 173-8601 (Japan); Takahashi, Shusuke; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru [Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

    2015-12-15

    We investigate the impact of strain on photovoltaic current (J{sub z}) characteristics for iron-doped LiNbO{sub 3} (Fe-LN) under visible light illumination by thin-film experiments. The J{sub z} values are demonstrated to be dramatically enhanced for the film with a tensile strain along the P{sub s} direction, which is over 500 times as large as that of the bulk (strain-free) Fe-LN crystals. Density functional theory (DFT) calculations show that the tensile strain increases an off-center displacement of Fe{sup 2+} that is opposite to the P{sub s} direction. Our experimental and DFT study demonstrates that the control of the lattice strain is effective in enhancing the photovoltaic effect in the Fe-LN system. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Resistivity and Passivity Characterization of Ni-Base Glassy Alloys in NaOH Media

    Directory of Open Access Journals (Sweden)

    Khadijah M. Emran

    2018-01-01

    Full Text Available Resistivity and passivation behavior of two Ni-base bulk metallic glasses, with the nominal composition of Ni70Cr21Si0.5B0.5P8C ≤ 0.1Co ≤ 1Fe ≤ 1 (VZ1 and Ni72.65Cr7.3-Si6.7B2.15C ≤ 0.06Fe8.2Mo3 (VZ2, in various concentrations of NaOH solutions were studied. The investigations involved cyclic polarization (CP, electrochemical impedance spectroscopy (EIS, and electrochemical frequency modulation (EFM methods. Cyclic polarization measurements showed spontaneous passivation for both Ni-base glassy alloys at all alkaline concentrations, due to the presence of chromium as an alloying element that formed an oxide film on the alloy surface. The EIS analysis showed that the passive layers grown on the two Ni-base glassy alloy surfaces are formed by a double oxide layer structure. Scanning electron microscope (SEM examinations of the electrode surface showed Cr, Ni, Fe, and O rich corrosion products that reduced the extent of corrosion damage. Atomic force microscopy (AFM imaging technique was used to evaluate the topographic and morphologic features of surface layers formed on the surface of the alloys.

  16. Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb{sub 2}MB{sub 2} (M=Fe, Ru, Os) from first principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Touzani, Rachid St.; Fokwa, Boniface P.T., E-mail: Boniface.Fokwa@ac.rwth-aachen.de

    2014-03-15

    The Nb{sub 2}FeB{sub 2} phase (U{sub 3}Si{sub 2}-type, space group P4/mbm, no. 127) is known for almost 50 years, but until now its magnetic properties have not been investigated. While the synthesis of Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128, a twofold superstructure of U{sub 3}Si{sub 2}-type) with distorted Nb-layers and Os{sub 2}-dumbbells was recently achieved, “Nb{sub 2}RuB{sub 2}” is still not synthesized and its crystal structure is yet to be revealed. Our first principles density functional theory (DFT) calculations have confirmed not only the experimental structures of Nb{sub 2}FeB{sub 2} and Nb{sub 2}OsB{sub 2}, but also predict “Nb{sub 2}RuB{sub 2}” to crystalize with the Nb{sub 2}OsB{sub 2} structure type. According to chemical bonding analysis, the homoatomic B–B interactions are optimized and very strong, but relatively strong heteroatomic M–B, B–Nb and M–Nb bonds (M=Fe, Ru, Os) are also found. These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of these ternary borides. The density-of-states at the Fermi level predicts metallic behavior, as expected, from metal-rich borides. Analysis of possible magnetic structures concluded preferred antiferromagnetic ordering for Nb{sub 2}FeB{sub 2}, originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them. -- Graphical abstract: Nb{sub 2}FeB{sub 2} (U{sub 3}Si{sub 2} structure type, space group P4/mbm, no. 127) is predicted to order antiferromagnetically, due to the presence of iron chains which show ferromagnetic interactions in the chains and antiferromagnetic interactions between them. “Nb{sub 2}RuB{sub 2}” is predicted to crystallize with the recently discovered Nb{sub 2}OsB{sub 2} twofold superstructure (space group P4/mnc, no. 128) of U{sub 3}Si{sub 2} structure type. The building of ruthenium dumbbells instead of chains along [001] is found to be

  17. Experimental investigation of the Zr corner of the ternary Zr-Nb-Fe phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, M.S. E-mail: granovsk@cnea.gov.ar; Canay, M.; Lena, E.; Arias, D

    2002-04-01

    Intermediate phases in the Zr-rich region of the Zr-Nb-Fe system have been investigated by X-ray diffraction, optical and electron microscopy and electron microprobe analysis. The chemical composition ranges covered by the alloys studied here are: (41-97) at.% Zr, (32-0.9) at.% Nb and (0.6-38) at.% Fe. The phases found in this region were: the solid solutions {alpha}-Zr and {beta}-Zr, the intermetallic Zr{sub 3}Fe with less than 0.2 at.% Nb in solution, two new ternary intermetallic compounds (Zr+Nb){sub 2}Fe '{lambda}{sub 1}' with a cubic Ti{sub 2}Ni-type structure in the composition range (2.4-13) at.% Nb and (31-33) at.% Fe, and (Fe+Nb){sub 2}Zr '{lambda}{sub 2}' indexed as hexagonal Laves phase MgZn{sub 2} type (C14) with a wide range of compositions close to (35-37) at.% Zr, (12-31) at.% Nb and (32-53) at.% Fe.

  18. Experimental investigation of the Zr corner of the ternary Zr-Nb-Fe phase diagram

    International Nuclear Information System (INIS)

    Granovsky, M.S.; Canay, M.; Lena, E.; Arias, D.

    2002-01-01

    Intermediate phases in the Zr-rich region of the Zr-Nb-Fe system have been investigated by X-ray diffraction, optical and electron microscopy and electron microprobe analysis. The chemical composition ranges covered by the alloys studied here are: (41-97) at.% Zr, (32-0.9) at.% Nb and (0.6-38) at.% Fe. The phases found in this region were: the solid solutions α-Zr and β-Zr, the intermetallic Zr 3 Fe with less than 0.2 at.% Nb in solution, two new ternary intermetallic compounds (Zr+Nb) 2 Fe 'λ 1 ' with a cubic Ti 2 Ni-type structure in the composition range (2.4-13) at.% Nb and (31-33) at.% Fe, and (Fe+Nb) 2 Zr 'λ 2 ' indexed as hexagonal Laves phase MgZn 2 type (C14) with a wide range of compositions close to (35-37) at.% Zr, (12-31) at.% Nb and (32-53) at.% Fe

  19. Glass Formation, Chemical Properties and Surface Analysis of Cu-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2011-04-01

    Full Text Available This paper reviews the influence of alloying elements Mo, Nb, Ta and Ni on glass formation and corrosion resistance of Cu-based bulk metallic glasses (BMGs. In order to obtain basic knowledge for application to the industry, corrosion resistance of the Cu–Hf–Ti–(Mo, Nb, Ta, Ni and Cu–Zr–Ag–Al–(Nb bulk glassy alloy systems in various solutions are reported in this work. Moreover, X-ray photoelectron spectroscopy (XPS analysis is performed to clarify the surface-related chemical characteristics of the alloy before and after immersion in the solutions; this has lead to a better understanding of the correlation between the surface composition and the corrosion resistance.

  20. Metallurgical study and phase diagram calculations of the Zr-Nb-Fe-(Sn,O) system

    International Nuclear Information System (INIS)

    Toffolon, C.

    2000-01-01

    The Framatome M5 TM Zr-Nb-O alloy with small amounts of Fe is of interest for nuclear applications (PWR fuel cladding).The behaviour of this kind of alloy for in-service conditions strongly depends on the microstructure. Therefore, a metallurgical study of alloys of the Zr-Nb-Fe-(O-Sn) system has been developed in order to study the influence of chemical composition variabilities of Nb, Fe and O and thermal treatments on the resultant microstructure. In order to get some insight on the physical metallurgy of Zr-Nb-Fe-(Sn,O) alloys and to minimize the experiments, it is useful to build a thermodynamic database. With this object, it was necessary to re-optimize and to calculate the low order binary systems such as Fe-Nb and Nb-Sn in order to assess the Zr-Nb-Fe-(Sn,O) system. Then, the experimental studies concerned: the influence of small variations in Nb and O contents on the α/β transus temperatures. A comparison between experimental results and thermodynamic predictions showed a good agreement; the precipitation kinetics of βNb and intermetallic phases in the α phase domain. These experiments showed that the kinetics depends on the initial metallurgical conditions; the determination of the crystallographic structure and the stoichiometry of the ternary Zr-Nb-Fe intermetallic compounds as a function of the temperature. Finally, these experimental data were used to propose a first assessment of the Zr-Nb-Fe(O∼1200 ppm) system. (author)

  1. Influence of Li/Nb ratios on defect structure and photorefractive properties of Zn: In: Fe: LiNbO 3 crystals

    Science.gov (United States)

    Dai, Li; Su, Yan-Qing; Wu, Shi-Ping; Guo, Jing-Jie; Xu, Chao; Xu, Yu-Heng

    2011-04-01

    A series of Zn: In: Fe: LiNbO3 crystals are grown by the Czochralski technique with various ratios of Li/Nb = 0.94, 1.05, 1.20 and 1.38 in the melt. The Zn, In, Fe, Nb and Li concentrations in the crystals are analyzed by inductively coupled plasma (ICP) spectrometry. The results indicate that with increasing the [Li]/[Nb] ratio in melt, [Li]/[Nb] ratio increases and goes up continuously in the crystal, the segregation coefficients of both Zn and In ions decrease. The absorption spectra measurement and two-wave coupling experiment are employed to study the effect of [Li]/[Nb] ratio on photorefractive properties of Zn: In: Fe: LiNbO3 crystals. It is found that the [Li]/[Nb] ratio increases, the write time is shortened and the photorefractive sensitivity is improved.

  2. Temperature dependence of the resistivity and tunneling magnetoresistance of sputtered FeHf(Si)O cermet films

    NARCIS (Netherlands)

    Strijkers, G.J.; Swagten, H.J.M.; Rulkens, B.; Bitter, R.H.J.N.; Jonge, de W.J.M.; Bloemen, P.J.H.; Schep, K.M.

    1998-01-01

    We have studied the tunneling resistivity and magnetoresistance of reactive sputter deposited FeHfO and FeHfSiO thin granular films. Maximum magnetoresistance ratios at room temperature of 2% and 3.2% were observed for films with compositions of Fe47Hf10O43 and Fe40Hf6Si6O48, respectively. The

  3. Effects of Nb content on the Zr{sub 2}Fe intermetallic stability

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C. E-mail: ciramos@cnea.gov.ar; Saragovi, C.; Granovsky, M.; Arias, D

    2003-02-01

    With the aim of studying the stability range of the Zr{sub 2}Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase ({lambda}{sub 1}) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr{sub 2}Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr{sub 2}Fe+{lambda}{sub 1} region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed.

  4. Study of the central region of the ternary Zr-Nb-Fe diagram

    International Nuclear Information System (INIS)

    Ramos, Cinthia; Saragovi, Celia; Arias, Delia E.; Granovsky, Marta S.

    2003-01-01

    The aim of the present work is identifying and characterizing the intermetallic phases and the associated two-phase and three-phase fields of the central region of the Zr-Nb-Fe phase diagram. As cast and 900 C degrees heat treated samples of variable compositions, 10 1 : Fe (Nb x Zr 1-x ) 2 and λ 2 : Zr(Nb x Fe 1-x ) 2 ) were studied. (author)

  5. Thermodynamic Description Of Ternary Fe-B-X Systems. Part 2: Fe-B-Ni

    Directory of Open Access Journals (Sweden)

    Miettinen J.

    2014-06-01

    Full Text Available Przedstawiono termodynamiczny opis trójskładnikowego układu Fe-B-Ni w kontekście nowej bazy danych dla układów Fe-B-X (X = Cr, Ni, Mn, Si, Ti, V, C. Parametry termodynamiczne dwuskładnikowych stopów Fe-B. Fe-Ni i B-Ni zostały są zaczerpnięte z wcześniejszych opracowań, przy tym opis B-Ni został nieznacznie zmodyfikowany. Parametry dla układu Fe-B-Ni zostały zoptymalizowane w tej pracy w oparciu o eksperymentalne równowagi fazowe i dane termodynamiczne zaczerpnięte z literatury. Roztwory stałe w układzie Fe-B-Ni opisano przy użyciu modelu roztworu substytucyjnego, a borki traktowane są jako fazy stechiometryczne lub półstechiometryczne typu (A.BpCq opisane przy użyciu modelu dwu podsieci.

  6. Moessbauer study of proton-exchanged LiNbO3:Fe

    International Nuclear Information System (INIS)

    Engelmann, H.; Andler, G.; Dezsi, I.

    1990-01-01

    Topotactic proton exchange (Li against H) can be achieved by treating LiBnO 3 with appropriate acids. In order to investigate the effect of proton exchange on Fe-impurities we studied LiNbO 3 :Fe powder material treated in sulphuric acid and LiNbO 3 :Fe single crystals treated in benzoic acid by Moessbauer spectroscopy. During the topotactic ion exchange only the Li-ions are exchanged for protons, whereas the Fe-impurities are retained in the material. (orig.)

  7. High resolution TDPAC measurements on 181Ta in Hf2Fe, Hf2Co and Hf2Rh at high temperature

    International Nuclear Information System (INIS)

    Cekic, B.; Koicki, S.; Ivanovic, N.; Manasijevic, M.; Koteski, V.; Marjanovic, D.

    1998-01-01

    The time differential perturbed angular correlation measurements (TDPAC-method ) on 181 Ta ion probe in Hf 2 Co, Hf 2 Fe and Hf 2 Rh intermetallic compounds have been performed at 1170 K, using a fast - slow time spectrometer consisting of two BaF 2 detectors. The results of the measurements show the presence of two independent electric quadrupole interactions, compatible with the crystalline structure of these polycrystalline compounds. (authors)

  8. Metallurgical study and phase diagram calculations of the Zr-Nb-Fe-(Sn,O) system; Etude metallurgique et calculs des diagrammes de phases des alliages base zirconium du systeme: Zr-Nb-Fe-(O,Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Toffolon, C. [CEA/Saclay, Dept. d' Etudes du Comportement des Materiaux (DECM), 91 - Gif-sur-Yvette (France)]|[Paris-6 Univ., 75 (France)

    2000-07-01

    The Framatome M5{sup TM} Zr-Nb-O alloy with small amounts of Fe is of interest for nuclear applications (PWR fuel cladding).The behaviour of this kind of alloy for in-service conditions strongly depends on the microstructure. Therefore, a metallurgical study of alloys of the Zr-Nb-Fe-(O-Sn) system has been developed in order to study the influence of chemical composition variabilities of Nb, Fe and O and thermal treatments on the resultant microstructure. In order to get some insight on the physical metallurgy of Zr-Nb-Fe-(Sn,O) alloys and to minimize the experiments, it is useful to build a thermodynamic database. With this object, it was necessary to re-optimize and to calculate the low order binary systems such as Fe-Nb and Nb-Sn in order to assess the Zr-Nb-Fe-(Sn,O) system. Then, the experimental studies concerned: the influence of small variations in Nb and O contents on the {alpha}/{beta} transus temperatures. A comparison between experimental results and thermodynamic predictions showed a good agreement; the precipitation kinetics of {beta}Nb and intermetallic phases in the {alpha} phase domain. These experiments showed that the kinetics depends on the initial metallurgical conditions; the determination of the crystallographic structure and the stoichiometry of the ternary Zr-Nb-Fe intermetallic compounds as a function of the temperature. Finally, these experimental data were used to propose a first assessment of the Zr-Nb-Fe(O{approx}1200 ppm) system. (author)

  9. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.T.; Hong, S.H.; Lee, C.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, J.M., E-mail: jinman_park@hotmail.com [Materials Research Center, Samsung Advanced Institute of Technology (SAIT), San 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); Kim, T.W.; Lee, W.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yim, H.I. [Department of Physics, Sookmyung Women’s University, Hyochangwongil 52, Yongsan-ku, Seoul 140-742 (Korea, Republic of); Kim, K.B., E-mail: kbkim@sejong.ac.kr [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2014-02-25

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe{sub 52}Co{sub 20−x}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub x} alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe{sub 52}Co{sub 17}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub 3} bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept.

  10. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    International Nuclear Information System (INIS)

    Kim, J.T.; Hong, S.H.; Lee, C.H.; Park, J.M.; Kim, T.W.; Lee, W.H.; Yim, H.I.; Kim, K.B.

    2014-01-01

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe 52 Co 20−x B 20 Si 4 Nb 4 Cr x alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe 52 Co 17 B 20 Si 4 Nb 4 Cr 3 bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept

  11. Systematic study on the electronic structure and mechanical properties of X2BC (X = Mo, Ti, V, Zr, Nb, Hf, Ta and W)

    International Nuclear Information System (INIS)

    Bolvardi, H; Emmerlich, J; To Baben, M; Music, D; Schneider, J M; Von Appen, J; Dronskowski, R

    2013-01-01

    In this work the electronic structure and mechanical properties of the phases X 2 BC with X =Ti, V, Zr, Nb, Mo, Hf, Ta, W (Mo 2 BC-prototype) were studied using ab initio calculations. As the valence electron concentration (VEC) per atom is increased by substitution of the transition metal X, the six very strong bonds between the transition metal and the carbon shift to lower energies relative to the Fermi level, thereby increasing the bulk modulus to values of up to 350 GPa, which corresponds to 93% of the value reported for c-BN. Systems with higher VEC appear to be ductile as inferred from both the more positive Cauchy pressure and the larger value of the bulk to shear modulus ratio (B/G). The more ductile behavior is a result of the more delocalized interatomic interactions due to larger orbital overlap in smaller unit cells. The calculated phase stabilities show an increasing trend as the VEC is decreased. This rather unusual combination of high stiffness and moderate ductility renders X 2 BC compounds with X = Ta, Mo and W as promising candidates for protection of cutting and forming tools.

  12. Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

    Science.gov (United States)

    Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

    metastable a-and b-BaTi2 O5 are constructed with non-centrosymmetric geometry TiO5 polyhedra, which provides higher potential for yielding high dielectric constants, pyroelectric and nonlinear op-tical properties than that of normal 4-or 6-coordinate Ti-O polyhedra. In addition, all lanthanide elements can be doped into the unusual glassy BaTi2 O5 structure to open up new possibilities for creating new bulk glasses, metastable phases and nano-crystalline ceramics with peculiar electronic and optical properties, such as giant permittivity and strong upconversion luminescence. References [1] Y. Akishige, K. Fukano, and H. Shigematsu, Jpn. J. Appl. Phys. p2, 42, L946 (2003). [2] J. Yu, Y. Arai, T. Masaki, T. Ishikawa, S. Yoda, S. Kohara, H. Taniguchi, M. Itoh, and Y. Kuroiwa, Chem. Matter. 18 p.2169 (2006) [3] J. Yu, S. Kohara, S. Nozawa, K. Itoh, S. Miyoshi, Y. Arai, A. Masuno, H. Taniguchi, M. Itoh, M. Takata, T. Fukunaga, S. Koshihara, Y. Kuroiwa, and S. Yoda, Chem. Matter. 21, p259 (2009).

  13. Annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Alves, M. J. P.; Gonzalez-Chavez, D. E.; Sommer, R. L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)

    2015-03-28

    We systematically investigate the annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films with thickness of 100 nm. We correlate the non-uniform residual stress obtained from grazing incidence x-ray diffraction measurements with the ferromagnetic resonance (FMR) linewidth due to effective field inhomogeneities measured from broadband ferromagnetic resonance absorption measurements. We also estimate the annealing temperature effect on the Gilbert and two-magnon scattering contributions to the total ferromagnetic resonance FMR linewidth. We show that the effective field inhomogeneities constitute the main contribution to the microwave linewidth, while this contribution is related to the non-uniform residual stress in the films which is reduced by thermal annealing.

  14. Structural, magnetic and optical properties of Y bFe{sub 2}O{sub 4} films deposited by spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Tatsuo, E-mail: tfujii@cc.okayama-u.ac.jp; Okamura, Naoya; Hashimoto, Hideki; Nakanishi, Makoto [Department of Applied Chemistry, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 (Japan); Kano, Jun [Department of Applied Chemistry, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 (Japan); Japan Science and Technology Agency, PRESTO, Kawaguchi, Saitama 332-0012 (Japan); Ikeda, Naoshi [Department of Physics, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 (Japan)

    2016-08-15

    Rare-earth iron oxides (RFe{sub 2}O{sub 4}) have attracting attention as new electronic device materials because of their numerous functionalities, such as electronic ferroelectricity, ferrimagnetism, and high infrared absorption. In this paper, nearly monophasic Y bFe{sub 2}O{sub 4} films were prepared on α-Al{sub 2}O{sub 3}(001) substrates by the spin coating method using an aqueous-based Y bFe{sub 2}O{sub 4} solution. The solution was composed of a stoichiometric ratio of Y b(CH{sub 3}COO){sub 3} and Fe(NO{sub 3}){sub 3} with excess chelating agents. After heat treatment above 800 °C, well-crystallized and highly (001)-oriented Y bFe{sub 2}O{sub 4} started to epitaxially form on the substrate under controlled oxygen partial pressure with H{sub 2}/CO{sub 2} gas mixtures. X-ray pole figure analysis confirmed the following epitaxial relationship: Y bFe{sub 2}O{sub 4}[100](001)//α-Al{sub 2}O{sub 3}[100](001). Moreover formation of an Fe{sub 3}O{sub 4} interracial layer between Y bFe{sub 2}O{sub 4} and α-Al{sub 2}O{sub 3} was detected by high-resolution transmission electron microscopy. Presence of the Fe{sub 3}O{sub 4} interracial layer seemed to release the lattice misfit with the substrate. The Fe{sup 2+}/Fe{sup 3+} ratio in the obtained Y bFe{sub 2}O{sub 4} films was nearly stoichiometric and the indirect bandgap assigned to Fe{sup 2+} → Fe{sup 3+} charge transfer excitation was found to be ∼0.4 eV by optical spectroscopy. A clear magnetic transition from the paramagnetic state to the ferrimagnetic state occurred at ∼230 K.

  15. Effect of Y addition on crystallization behavior and soft-magnetic properties of Fe{sub 78}Si{sub 9}B{sub 13} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zhanwei, Liu; Dunbo, Yu, E-mail: yudb2008@126.com; Kuoshe, Li; Yang, Luo; Chao, Yuan; Zilong, Wang; Liang, Sun; Kuo, Men

    2017-08-15

    Highlights: • Thermal stability of Fe-Si-B amorphous alloy is enhanced by Y addition. • Y addition can improve soft magnetic properties of Fe-Si-B amorphous alloy. • Decomposition of metastable Fe{sub 3}B phase is related to Y content in Fe-Si-B matrix. - Abstract: A series of amorphous Fe-Si-B ribbons with various Y addition were prepared by melt-spinning. The effect of Y addition on crystallization behavior, thermal and magnetic properties was systematically investigated. With the increase of Y content, the initial crystallization temperature shifted to a higher temperature, indicating that the thermal stability of amorphous state in Fe-Si-B-Y ribbon is enhanced compared to that of Fe-Si-B alloy. Meanwhile, compared to the two exothermic peaks in the samples with lower Y content, a new exothermic peak was found in the ribbons with Y content higher than 1 at%, which corresponded to the decomposition of metastable Fe{sub 3}B phase. Among all the alloys, Fe{sub 76.5}Si{sub 9}B{sub 13}Y{sub 1.5} alloy exhibits optimized magnetic properties, with high saturation magnetization M{sub s} of 187 emu/g and low coercivity H{sub cJ} of 7.6 A/m.

  16. Preparation of Nb thin films with bulk transition temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Peirce, L H [Florida State Univ., Tallahassee (USA). Dept. of Physics

    1984-08-01

    Thin films (1000-2000 A) of Nb were prepared with bulk transition temperatures (9.25 K) by evaporation from an electron gun. Necessary substrate temperatures, evaporation rates and H/sub 2/O pressures were determined.

  17. Semiquantitative spectrographic analysis of nuclear interest minerals and of various products; Analisis espectrografico semicuantitativo de minerales de interes nuclear y productos diversos

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Gonzalez, F; Roca Adell, M; Fernandez Cellini, R

    1958-07-01

    Because the great number of samples of various kinds receiving in the Chemical Division, minerals in the most part, for its complete analysis, a rapid spectrographic method has been developed. It permits the determination of the following elements with a semiquantitative character. Al, As, Ag, Au, B, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, Hf, Hn, In, K, La, Li, Mg, Mn, Mo, Na, Nb, P, Pb, Pt, Sb, Si, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr. (Author) 14 refs.

  18. Peierls-distorted Ru-chains and boron dumbbells in Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} from first-principles calculations and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Touzani, Rachid S.; Mbarki, Mohammed; Chen, Ximeng [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Fokwa, Boniface P.T. [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Department of Chemistry, University of California Riverside (UCR), Riverside, CA (United States)

    2016-09-15

    Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases were recently predicted by GGA-VASP structure optimization to crystallize in the Nb{sub 2}OsB{sub 2}-type structure. Although the Fe-based (Mo{sub 2}FeB{sub 2} type) and Os-based (Nb{sub 2}OsB{sub 2} type, superstructure variant of Mo{sub 2}FeB{sub 2} type) analogues have been synthesized and characterized successfully, the Ru-based phases remained unknown. Crystal structure prediction of Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases, using an evolutionary algorithm, led to the AlMn{sub 2}B{sub 2}-type structure in contrast to the aforementioned optimization; however, phonon calculations showed that the Nb{sub 2}OsB{sub 2}-type phases are dynamically more stable than the AlMn{sub 2}B{sub 2}-type phases. A slightly modified synthetic strategy finally led to the successful preparation of the predicted phases. The extremely quick arc-melting procedure, under argon atmosphere, not only led to a quantitative amount of the phases but also to single crystals suitable for structure determination. Powder and single-crystal X-ray diffraction as well as EDX analysis of the metal ratio have confirmed the GGA-VASP structure optimization: Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} compounds indeed crystallize isotypically with Nb{sub 2}OsB{sub 2} structure, a superstructure variant of Mo{sub 2}FeB{sub 2} type, in which B-dumbbells and Peierls-distorted Ru-chains are found. Susceptibility measurements on a Ta{sub 2}RuB{sub 2} single crystal reveal no superconducting transition down to 2 K, even though some features in the band structures of both phases, similar to those reported in superconducting NbRuB, hinted at possible superconductivity. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Crack initiation and fracture features of Fe–Co–B–Si–Nb bulk metallic glass during compression

    Directory of Open Access Journals (Sweden)

    S. Lesz

    2016-01-01

    Full Text Available The aim of the paper was investigation crack initiation and fracture features developed during compression of Fe-based bulk metallic glass (BMG. These Fe-based BMG has received great attention as a new class of structural material due to an excellent properties (e.g. high strength and high elasticity and low costs. However, the poor ductility and brittle fracture exhibited in BMGs limit their structural application. At room temperature, BMGs fails catastrophically without appreciable plastic deformation under tension and only very limited plastic deformation is observed under compression or bending. Hence a well understanding of the crack initiation and fracture morphology of Fe-based BMGs after compression is of much importance for designing high performance BMGs. The raw materials used in this experiment for the production of BMGs were pure Fe, Co, Nb metals and nonmetallic elements: Si, B. The Fe–Co–B–Si–Nb alloy was cast as rods with three different diameters. The structure of the investigated BMGs rod is amorphous. The measurement of mechanical properties (Young modulus - E, compressive stress - σc, elastic strain - ε, unitary elastic strain energy – Uu were made in compression test. Compression test indicates the rods of Fe-based alloy to exhibit high mechanical strength. The development of crack initiation and fracture morphology after compression of Fe-based BMG were examined with scanning electron microscope (SEM. Fracture morphology of rods has been different on the cross section. Two characteristic features of the compressive fracture morphologies of BMGs were observed. One is the smooth region. Another typical feature of the compressive fracture morphology of BMGs is the vein pattern. The veins on the compressive fracture surface have an obvious direction as result of initial displace of sample along shear bands. This direction follows the direction of the displacement of a material. The formation of veins on the

  20. Collapse of the magnetic moment under pressure of AFe{sub 2} (A=Y, Zr, Lu and Hf) in the cubic Laves phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenxu, E-mail: xwzhang@uestc.edu.cn; Zhang, Wanli

    2016-04-15

    The electronic structures of four Laves phase iron compounds (e.g. YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2}) have been calculated with a state-of-the-art full potential electronic structure code. Our theoretical work predicted that the magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its electronic origin is provided by the sharp peaks in the density of states near the Fermi level. It is shown that a first order quantum phase transition can be expected under pressure in Y(Zr, or Lu)Fe{sub 2}, while a second order one in HfFe{sub 2}. The bonding characteristics are discussed to elucidate the equilibrium lattice constant variation. The large spontaneous volume magnetostriction gives one of the most important characteristics of these compounds. Invar anomalies in these compounds can be partly explained by the current work when the fast continuous magnetic moment decrease with the decrease of the lattice constant was properly considered. This work may be as a first insight into the rich world of quantum phase transition and Invar mechanism in these Laves phase compounds. - Highlights: • Magnetic moment of YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2} collapses under pressure. • The transition in Y(Zr or Lu) Fe{sub 2} under pressure is first order. • The transition in HfFe{sub 2} under pressure is second order. • The Invar effects in the compounds can be put into the magnetostriction model.

  1. Free volume and elastic properties changes in Cu-Zr-Ti-Pd bulk glassy alloy on heating

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.; Yavari, Alain Reza; Fukuhara, Mikio; Ota, Katsumi; Xie, Guoqiang; Vaughan, Gavin; Inoue, Akihisa

    2007-01-01

    The variation of free volume and elastic properties of the Cu 55 Zr 30 Ti 10 Pd 5 glassy alloy on heating was studied. The structure changes on heating were studied by synchrotron X-ray diffraction, differential scanning and isothermal calorimetries. The studied glassy alloy shows a rather high Poisson's ratio exceeding 0.42 which is maintained after the structure relaxation and primary devitrification. Young's and Shear modules decrease upon primary devitrification while Bulk modulus exhibits a maximum after structural relaxation

  2. Nuclear orientation of 9597Nb and 95Zr in ZrFe2

    International Nuclear Information System (INIS)

    Krane, K.S.; Olsen, C.E.; Rosenblum, S.S.; Steyert, W.A.

    1976-01-01

    The angular distribution anisotropies of γ rays were measured following the decays of 95 , 97 Nb and 95 Zr oriented at low temperatures in the ferromagnetic Laves phase compound ZrFe 2 . The magnetic hyperfine field of Nb in ZrFe 2 was deduced to be 9.4+-1.6 T; that of Zr in ZrFe 2 was estimated to be 15+-4 T. The nuclear magnetic moment of 97 Nb was deduced to be μ = (7.5+-1.4) μ/subN/

  3. Surface and bulk magnetic properties of as-quenched FeNbB ribbons

    Czech Academy of Sciences Publication Activity Database

    Životský, O.; Postava, K.; Kraus, Luděk; Juraszek, J.; Jirásková, Yvonna; Teillet, J.; Barčová, K.; Švec, P.; Janičkovič, D.; Pištora, J.

    2008-01-01

    Roč. 320, č. 8 (2008), s. 1535-1540 ISSN 0304-8853 R&D Projects: GA ČR GA202/05/2111; GA AV ČR KAN400100653 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z10100520 Keywords : Surface nanocrystallization * Fe-based ribbon * depth profile Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2008

  4. Growth and photo-response of NbSe2 and NbS2 crystals

    Science.gov (United States)

    Patel, Kunjal; Solanki, G. K.; Pataniya, Pratik; Patel, K. D.

    2018-05-01

    Transition metal dichalcogenides(TMDCs) have attracted intense research efforts due to their drastic properties change as we move towards ultra-thin crystalline layers from their bulk counterparts. Many well studied members of this family such as MoS2, WS2, WSe2, WS2 etc. have shown potential for flexible electronic devices including photovoltaic applications. The TMDCs like NbSe2 and NbS2 are relatively less studied layered compounds consisting of staked sandwiches of Se-Nb-Se/S-Nb-Se tri-layers with strong covalent/ionic intra layer bonds and weak Van der Waals interlayer interactions. In the present work, author have grown the crystals of NbSe2 and NbS2 by Direct Vapour Transport (DVT) technique and the material composition is confirmed using EDAX data. Photoelectrochemical (PEC) solar cell measurements are performed under monochromatic light illumination at different intensities and various solar cell parameters are calculated. These crystalline semiconductor electrodes were also analysed by photocurrent-voltage characteristics in a PEC solar cell structure (Cu/NbSe2/(0.1M K4Fe(CN)6 + 0.1M K3Fe(CN)6) and Cu/NbS2/(0.1M K4Fe(CN)6 +0.1M K3Fe(CN)6)). Blue coloured light gave the maximum efficiency. For further analysis of photodetection properties of the grown crystals, Ag painted broad low contact resistance electrical contacts were drawn from the crystals and its transient photoresponse was studied to evaluate different detector parameters.

  5. Magnetic properties and macroscopic heterogeneity of FeCoNbB Hitperms

    Science.gov (United States)

    Butvin, Pavol; Butvinová, Beata; Sitek, Jozef; Degmová, Jarmila; Vlasák, Gabriel; Švec, Peter; Janičkovič, Dušan

    Nanocrystalline ribbons of Fe 81-xCo xNb 7B 12 (where x ranges from 0 to 40.5 at%) Hitperm alloys have been investigated as to their basic magnetic properties and the influence of the macroscopic heterogeneity. Different crystalline share at surfaces compared with the volume average is observed by conversion electron Mössbauer spectroscopy (CEMS) and Mössbauer spectroscopy (MS), respectively. This marks the presence of macroscopic heterogeneity in these Hitperms. The heterogeneity is generally more significant in Ar-annealed samples than in the vacuum-annealed ones. The characteristic slant hysteresis loops (hard-ribbon-axis) are seen as a rule with few exceptions. An inspection of hysteresis loop response of resin potted samples shows that the surfaces bi-axially squeeze the ribbon interior in heterogeneous Hitperms when the ribbons cool down after annealing. Certain compositions show macroscopic viscous flow prior to crystallization so the heterogeneity gets another chance to induce anisotropy during annealing. The induction attains 1.5 T but saturates poorly due to the heterogeneity and the ensuing anisotropy. Moreover the heterogeneity appears to hamper the crystallization within the ribbon interior. Unlike Finemets, the density of these Hitperms show no pronounced trend with annealing.

  6. Fundamental Thermal and Mechanical Properties of Boride Ceramics

    Science.gov (United States)

    2014-02-28

    Zr ,Y)B2 ( Zr ,Hf)B2 ( Zr ,Ti)B2 ZrB2 El ec tri ca l R es is tiv ity (µ Ω -c m ) Temperature (°C) Figure 17. Electrical resistivity as a function...family as Zr , namely Ti and Hf, had minimal effect on thermal conductivity, while others such as Nb , Ta, and W had an increasing impact based on their...diffusivity (α), heat capacity (Cp) from the NIST-JANAF tables, and bulk density (ρ) using Equation 6. (5) (6) Electrical resistivity

  7. Development of Cu-Hf-Al ternary systems and tungsten wire/particle reinforced Cu48Hf43Al9 bulk metallic glass composites for strengthening

    International Nuclear Information System (INIS)

    Park, Joyoung; An, Jihye; Choi-Yim, Haein

    2010-01-01

    Stable bulk glass forming alloys can be developed over a wide range of compositions in Cu-Hf-Al ternary systems starting from the Cu 49 Hf 42 Al 9 bulk metallic glass. Ternary Cu-Hf-Al alloys can be cast directly from the melt into copper molds to form fully amorphous strips with thicknesses of 1 to 6 mm. The maximum critical diameter of the new Cu-Hf-Al ternary alloy was 6 mm. X-ray diffraction patterns were used to confirm the amorphous nature of the ternary Cu-Hf-Al alloys. To increase the toughness of these metallic glasses, we reinforced the Cu 48 Hf 43 Al 9 bulk metallic glass-forming liquid with a 50% volume fraction of tungsten particles and an 80% volume fraction of tungsten wires with diameters of 242.4 μm. Composites with a critical diameter of 7 mm and length 70 mm were synthesized. The structure of the composites was confirmed by using X-ray diffraction (XRD), and the scanning electron microscopy (SEM). The mechanical properties of the composites were studied in compression tests. The thermal stability and the crystallization processes of the Cu-Hf-Al alloys and composites were investigated by using differential scanning calorimetry (DSC). Values of the glass transition temperature (T g ), the crystallization temperature (T x ), and the supercooled liquid region (ΔT = T x - T g ) are given in this paper.

  8. Temperature dependence of the magnetostriction and the induced anisotropy in nanocrystalline FeCuNbSiB alloys, and their fluxgate properties

    DEFF Research Database (Denmark)

    Nielsen, Otto V; Petersen, Jan Raagaard

    1994-01-01

    Making use of the stress induced magnetic anisotropy in some iron-rich FeCuNbSiB nanocrystalline materials we studied the thermal dependence of their magnetostriction which becomes zero below the Curie temperature. The choice of a suitable composition and annealing temperature results in materials...... with zero magnetostriction at room temperature. Due to the low magnetostriction these materials have very promising fluxgate properties which were studied as well...

  9. Thermal and electronic charge transport in bulk nanostructured Zr0.25Hf0.75NiSn composites with full-Heusler inclusions

    International Nuclear Information System (INIS)

    Makongo, Julien P.A.; Misra, Dinesh K.; Salvador, James R.; Takas, Nathan J.; Wang, Guoyu; Shabetai, Michael R.; Pant, Aditya; Paudel, Pravin; Uher, Ctirad; Stokes, Kevin L.; Poudeu, Pierre F.P.

    2011-01-01

    Bulk Zr 0.25 Hf 075 NiSn half-Heusler (HH) nanocomposites containing various mole fractions of full-Heusler (FH) inclusions were prepared by solid state reaction of pre-synthesized HH alloy with elemental Ni at 1073 K. The microstructures of spark plasma sintered specimens of the HH/FH nanocomposites were investigated using transmission electron microscopy and their thermoelectric properties were measured from 300 K to 775 K. The formation of coherent FH inclusions into the HH matrix arises from solid-state Ni diffusion into vacant sites of the HH structure. HH(1-y)/FH(y) composites with mole fraction of FH inclusions below the percolation threshold, y∼0.2, show increased electrical conductivity, reduced Seebeck coefficient and increased total thermal conductivity arising from gradual increase in the carrier concentration for composites. A drastic reduction (∼55%) in κ l was observed for the composite with y=0.6 and is attributed to enhanced phonon scattering due to mass fluctuations between FH and HH, and high density of HH/FH interfaces. - Graphical abstract: Large reduction in the lattice thermal conductivity of bulk nanostructured half-Heusler/full-Heusler (Zr 0.25 Hf 075 NiSn/ Zr 0.25 Hf 075 Ni 2 Sn) composites, obtained by solid-state diffusion at 1073 K of elemental Ni into vacant sites of the half-Heusler structure, arising from the formation of regions of spinodally decomposed HH and FH phases with a spatial composition modulation of ∼2 nm. Highlights: → Bulk composites from solid state transformation of half-Heusler matrix through Ni diffusion. → Formation of coherent phase boundaries between half-Heusler matrix and full-Heusler inclusion. → Alteration of thermal and electronic transports with increasing full-Heusler inclusion. → Enhanced phonon scattering at half-Heusler/ full-Heusler phase boundaries.

  10. Threshold current reduction for the metal–insulator transition in NbO2−x-selector devices: the effect of ReRAM integration

    International Nuclear Information System (INIS)

    Nandi, Sanjoy Kumar; Liu, Xinjun; Venkatachalam, Dinesh Kumar; Elliman, Robert Glen

    2015-01-01

    The threshold current for inducing the metal–insulator transition in a NbO 2−x selector element is shown to be affected by the properties of an adjacent memory element when integrated into a hybrid selector-memory device structure. Experimental results are reported for homogeneous NbO 2−x /Nb 2 O 5−y and heterogeneous NbO 2−x /HfO 2 device structures, and show that the threshold current is lower in both hybrid structures than in the selector element alone, and is lower in the heterogeneous structure than in the homogeneous structure. Finite element modeling of the selector-memory structure shows that this results primarily from current confinement produced by the filamentary conduction path in the resistive-switching memory layer (i.e. Nb 2 O 5−y or HfO 2 ), an observation that further implies a smaller diameter filament in HfO 2 than in Nb 2 O 5−y . The thermal and electrical conductivities of the memory layer are also shown to influence the threshold current, but to a lesser extent. (paper)

  11. Crystallographic and magnetic property changes upon hydrogen absorption in Hf2Fe

    International Nuclear Information System (INIS)

    Vulliet, P.; Teisseron, G.; Jeandey, C.; Oddou, J.L.; Yaouanc, A.

    1984-04-01

    We have found that the cubic intermetallic compound Hf 2 Fe can absorb almost up to five hydrogen atoms per formula at a pressure of one atmosphere. Hf 2 Fe is a Pauli magnet. Upon hydrogen absorption a magnetic moment definitively appears on iron, starting at approximately 1.5 hydrogen concentration. A maximum in the saturation magnetic moment is observed in Hf 2 FeH 3 . The static low field susceptibility presents a maximum value and a non reversible behaviour. These properties are characteristic of a disordered magnetic system (spin-glass like). The γ-γ perturbed angular correlation spectra indicate that at low concentration, the hydrogen is localized only near one type of Hf. From our Moessbauer data we measure a shift in the isomer-shift which is consistent with what is already known. When decreasing the temperature and increasing the hydrogen concentration the spectra get less resolved. This is linked to the fact that the samples are in a disordered magnetic phase

  12. Material science and solid state physics studies with positive muon spin precession. [fe(a1) alloys

    Science.gov (United States)

    Stronach, C. E.

    1979-01-01

    The hyperfine field on the muon, B sub hf, at interstitial sites in dilute Fe(Al) alloys was measured for four different concentrations of Al and as a function of temperature by the muon spin rotation method. The magnitude of B sub hf, which is negative, decreases at rates ranging from 0.09 + or - 0.03% per at.% Al at 200 K to an asymptotic limit of 0.35 + or - far above 440 K. This behavior shows that sites near the Al impurity are weakly repulsive to the muon, with an interaction potential of 13 + or - 3 meV. In order to fit the temperature dependence of the hyperfine field, it is necessary to hypothesize the existence of a small concentration of unidentified defects, possibly dislocations, which are attractive to the muon. Although the Al impurity acts as a non-magnetic hole in the Fe lattice, the observed decrease in B sub hf is only 35% of the decrease in the bulk magnetization. It is concluded that B sub hf is determined mainly by the enhanced screening of conduction electrons in Fe and Fe(Al). Since the influence of the Al impurity on the neighboring Fe monents is very small, most of the change in B sub hf is therefore attributed to the increase in conduction electron polarization of the Al impurity.

  13. The effect of liquid phase separation on the Vickers microindentation shear bands evolution in a Fe-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Askari-Paykani, M. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, North Kargar Street, Tehran 11356-4563 (Iran, Islamic Republic of); Nili Ahmadabadi, M., E-mail: nili@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, North Kargar Street, Tehran 11356-4563 (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Seiffodini, A. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, North Kargar Street, Tehran 11356-4563 (Iran, Islamic Republic of); Yazd University, Department of Material Science and Engineering, Yazd 84196 (Iran, Islamic Republic of)

    2013-11-15

    The Vickers microindentation experiments and associated plastic deformation in as-cast and annealed (Fe{sub 0.9}Ni{sub 0.1}){sub 77}Mo{sub 5}P{sub 9}C{sub 7.5}B{sub 1.5} bulk metallic glass was conducted. In addition to the bulk indentation behavior, the shear band morphology underneath the Vickers microindenter was examined by employing the bonded interface technique. Microstructural characterization revealed that a liquid phase separation occurred during melting process. Atomic force microscopy of the glassy matrix of the as-cast specimen reveals the composition inhomogeneity induced by the liquid phase separation. This effect generates shear band branching or deflection during the shear band propagation. For the bulk indentation, the trends in the hardness vs. indentation load were found related to the pressure sensitive index and the phase separation process simultaneously. The results show that the as-cast as well as the annealed specimens are deformed through semi-circular and radial shear bands. In addition, in the partially crystalized specimen, the change in the properties and microstructure of the BMG induced by the partial crystallization treatment and phase separation process resulted in tertiary shear bands formation.

  14. Phase stability in the Nb-rich region of the Nb-B-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, C.A.; Coelho, G.C.; Pinto, D.M. Jr.; Camargo Gandolpho, K.C. de; Borges, L.A. Jr.; Rodrigues, G. [Polo Urbo-Ind., Gleba, Lorena (Brazil). Dept. de Engenharia de Materiais

    2000-07-01

    Alloys of the Me-B-Si systems (Me-refractory metal) have been evaluated due to their potential for use as high temperature structural materials (T>1400 C). In the present study, the phase stability in the Nb-rich region of the Nb-B-Si system has been evaluated in terms of the current information associated to the Nb-Si, Nb-B and Nb-B-Si systems as well as our own data. For the experiments several as-cast and heat-treated alloys of the Nb-B and Nb-B-Si systems were investigated by X-ray diffraction and scanning electron microscopy. Concerning the Nb-B system the results indicated the existence of the eutectic reaction L ({proportional_to} 16 at%B) <=> Nb{sub ss}+NbB. The Nb{sub 3}B{sub 2} phase was not observed in the microstructure of as-cast alloys with composition in the range of 0 to 50 at%B. The analysis of heat-treated ternary alloys at 1600 C and 1750 C confirmed the existence of the Nb{sub ss}+T{sub 2} two-phase field at those temperatures. This T{sub 2}-phase is isomorphous of the {alpha}Nb{sub 5}Si{sub 3} and is formed through the partial substitution of Si atomos for B atoms in the lattice of the {alpha}Nb{sub 5}Si{sub 3}-phase. All ternary alloys prepared in the present study presented either Nb{sub ss} or T{sub 2} primary phases in the as-cast microstructures. In addition, those alloys presented an eutectic-like microstructure formed by the Nb{sub ss} and T{sub 2} phases in the interdendritic region. (orig.)

  15. Combinatorial processing libraries for bulk BiFeO3-PbTiO3 piezoelectric ceramics

    International Nuclear Information System (INIS)

    Hu, W.; Tan, X.; Rajan, K.

    2010-01-01

    A high throughput approach for generating combinatorial libraries with varying processing conditions for bulk ceramics has been developed. This approach utilized the linear temperature gradient in a tube furnace to screen a whole temperature range for optimized preparation. With this approach, the processing of 0.98[0.6BiFeO 3 -0.4PbTiO 3 ]-0.02Pb(Mg 1/3 Nb 2/3 )O 3 ceramic powders and pellets for high-temperature piezoelectric applications was demonstrated to identify the best synthesis conditions for phase purity. The dielectric property measurement on the as-processed solid solution ceramics confirmed the high Curie temperature and the improved loss tangent with the Pb(Mg 1/3 Nb 2/3 )O 3 doping. (orig.)

  16. Moessbauer Spectroscopy Studies of Some Intermetallics in the Zr-Nb-Fe System

    International Nuclear Information System (INIS)

    Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

    2002-01-01

    Samples with the following compositions: Zr 62 Nb 14 Fe 24 , Zr 65 Nb 10 Fe 25 and Zr 52 Nb 10 Fe 38 were studied by Moessbauer spectroscopy. All of them showed a ternary cubic Ti 2 Ni-type phase (QS: 0.30±0.02, IS: -0.14±0.01) and traces of Zr 2 Fe phase (QS: 0.86±0.03, IS: -0.29±0.01). Zrβ phase (QS: 0.22±0.01, IS: -0.11±0.01) was also detected except in the case of the richer Fe sample. In addition to these expected phases, a hexagonal MgZn 2 -type phase was determined. The assigned parameters for this phase are: QS: 0.38±0.04, IS: -0.28±0.02. These results suggest a revision of the diagram.

  17. Hyperfine field distribution of Fe83B17 glassy metal

    International Nuclear Information System (INIS)

    Miglierini, M.; Sitek, J.

    1990-01-01

    Convolutions of Gaussian and Lorentzian lines are proposed to fit the Moessbauer spectrum of Fe 83 B 17 metallic glass. The hyperfine field distribution is constructed from three Gaussian lines corresponding to the individual line pairs. (author). 1 fig., 7 refs

  18. Stress-induced phase transformation and room temperature aging in Ti-Nb-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cai, S.; Schaffer, J.E. [Fort Wayne Metals Research Products Corp, 9609 Ardmore Ave., Fort Wayne, IN 46809 (United States); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

    2017-01-05

    Room temperature deformation behavior of Ti-17Nb-1Fe and Ti-17Nb-2Fe alloys was studied by synchrotron X-ray diffraction and tensile testing. It was found that, after proper heat treatment, both alloys were able to recover a deformation strain of above 3.5% due to the Stress-induced Martensite (SIM) phase transformation. Higher Fe content increased the beta phase stability and onset stress for SIM transformation. A strong {110}{sub β} texture was produced in Ti-17Nb-2Fe compared to the {210}{sub β} texture that was observed in Ti-17Nb-1Fe. Room temperature aging was observed in both alloys, where the formation of the omega phase increased the yield strength (also SIM onset stress), and decreased the ductility and strain recovery. Other metastable beta Ti alloys may show a similar aging response and this should draw the attention of materials design engineers.

  19. Nanocrystalline structure formation and magnetic hysteresis properties of Y-Fe-Co-B alloys

    Czech Academy of Sciences Publication Activity Database

    Tereshina, I. S.; Tereshina, Evgeniya; Burkhanov, G.S.; Dobatkin, S.V.

    2010-01-01

    Roč. 25, č. 1 (2010), s. 82-87 ISSN 1606-5131. [International Symposium on Bulk Nanostructures Materials /2./. Ufa, 22.09.2009-26.09.2009] Institutional research plan: CEZ:AV0Z10100520 Keywords : R-Fe-B magnets * melt spinning * structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.649, year: 2010

  20. A thermodynamic evaluation of the Fe-Nb system

    International Nuclear Information System (INIS)

    Srikanth, S.; Petric, A.

    1994-01-01

    An optimised set of thermodynamic functions consistent with the phase diagram was derived for the Fe-Nb system from information on phase equilibria and thermodynamic data available in the literature. The thermodynamic properties of the intermediate ε (Fe 2 Nb) phase were described using the sublattice model. A Redlich-Kister equation was used to describe the excess thermodynamic functions of the liquid, bcc and fcc phases. For the μ phase, the enthalpy of formation was estimated from Miedema's model. The interaction coefficients were evaluated using an optimisation procedure employing a conjugate gradient method. The phase diagram and the thermodynamic functions calculated from the evaluated parameters are in good agreement with experimental data. (orig.)

  1. Electric field gradient at the Nb3M(M = Al, In, Si, Ge, Sn) and T3Al (T = Ti, Zr, Hf, V, Nb, Ta) alloys by perturbed angular correlation method

    International Nuclear Information System (INIS)

    Junqueira, Astrogildo de Carvalho

    1999-01-01

    The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb 3 M (M = Al, Si, Ge, Sn) and at the T site in the intermetallic compounds T 3 Al (T = Ti, Zr, Hf, V, Nb, Ta) was measured by Perturbed Angular Correlation (PAC) method using the well known gamma-gamma cascade of 133-482 keV in 181 Ta from the β - decay of 181 Hf. The compounds were prepared by arc melting the constituent elements under argon atmosphere along with radioactive 181 Hf substituting approximately 0.1 atomic percent of Nb and T elements. The PAC measurements were carried out at 295 K for all compounds and the efg was obtained for each alloy. The results for the efg in the T 3 Al compounds showed a strong correlation with the number of conduction electrons, while for the Nbs M compounds the efg behavior is influenced mainly by the p electrons of the M elements. The so-called universal correlation between the electronic and lattice contribution for the efg in metals was not verified in this work for all studied compounds. Measurements of the quadrupole frequency in the range of 100 to 1210 K for the Nb 3 Al compound showed a linear behaviour with the temperature. Superconducting properties of this alloys may probably be related with this observed behaviour. The efg results are compared to those reported for other binary alloys and discussed with the help of ab-initio methods. (author)

  2. Magnetic properties and macroscopic heterogeneity of FeCoNbB Hitperms

    Energy Technology Data Exchange (ETDEWEB)

    Butvin, Pavol [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)], E-mail: fyzipbut@savba.sk; Butvinova, Beata [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Sitek, Jozef; Degmova, Jarmila [Department of Nuclear Physics and Technology, FEI, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Vlasak, Gabriel; Svec, Peter; Janickovic, Dusan [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    2008-03-15

    Nanocrystalline ribbons of Fe{sub 81-x}Co{sub x}Nb{sub 7}B{sub 12} (where x ranges from 0 to 40.5 at%) Hitperm alloys have been investigated as to their basic magnetic properties and the influence of the macroscopic heterogeneity. Different crystalline share at surfaces compared with the volume average is observed by conversion electron Moessbauer spectroscopy (CEMS) and Moessbauer spectroscopy (MS), respectively. This marks the presence of macroscopic heterogeneity in these Hitperms. The heterogeneity is generally more significant in Ar-annealed samples than in the vacuum-annealed ones. The characteristic slant hysteresis loops (hard-ribbon-axis) are seen as a rule with few exceptions. An inspection of hysteresis loop response of resin potted samples shows that the surfaces bi-axially squeeze the ribbon interior in heterogeneous Hitperms when the ribbons cool down after annealing. Certain compositions show macroscopic viscous flow prior to crystallization so the heterogeneity gets another chance to induce anisotropy during annealing. The induction attains 1.5 T but saturates poorly due to the heterogeneity and the ensuing anisotropy. Moreover the heterogeneity appears to hamper the crystallization within the ribbon interior. Unlike Finemets, the density of these Hitperms show no pronounced trend with annealing.

  3. Moessbauer Spectroscopy Studies of Some Intermetallics in the Zr-Nb-Fe System

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C. [CNEA-UNSAM, Comision Nacional de Energia Atomica, Instituto de Tecnologia J. Sabato (Argentina); Saragovi, C. [Comision Nacional de Energia Atomica, Departamento de Fisica (Argentina); Granovsky, M.; Arias, D. [Comision Nacional de Energia Atomica, Departamento de Materiales (Argentina)

    2002-03-15

    Samples with the following compositions: Zr{sub 62}Nb{sub 14}Fe{sub 24}, Zr{sub 65}Nb{sub 10}Fe{sub 25} and Zr{sub 52}Nb{sub 10}Fe{sub 38} were studied by Moessbauer spectroscopy. All of them showed a ternary cubic Ti{sub 2}Ni-type phase (QS: 0.30{+-}0.02, IS: -0.14{+-}0.01) and traces of Zr{sub 2}Fe phase (QS: 0.86{+-}0.03, IS: -0.29{+-}0.01). Zr{beta} phase (QS: 0.22{+-}0.01, IS: -0.11{+-}0.01) was also detected except in the case of the richer Fe sample. In addition to these expected phases, a hexagonal MgZn{sub 2}-type phase was determined. The assigned parameters for this phase are: QS: 0.38{+-}0.04, IS: -0.28{+-}0.02. These results suggest a revision of the diagram.

  4. Effect of excess Mg and Excess Nb incorporation into the B-site of pyrochlore in the Pb-Mg-Nb-O system

    Directory of Open Access Journals (Sweden)

    Mergen, A.

    2002-12-01

    Full Text Available In the Pb-Mg-Nb-O system, excess Mg and excess Nb incorporation into the B-site of PMN pyrochlore were investigated along the compositons of Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x where x=0.1, 0.2, 0.3, 0.4, 0.522 and Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x where x=0.1, 0.2, 0.29 respectively. Excess Mg incorporation led to the formation of perovskite and excess Nb resulted in formation of Pb2Nb2O7 monoclinic pyrochlore. The densities of the PMN pyrochlore-PMN perovskite mixtures decreased with an increase in Mg concentration. The relative permittivity of the mixtures increased with decreasing pyrochlore content. The effect of pyrochlore on the permittivity follows the Weiner’s mixture rule up to a pyrochlore content of 50 vol%.

    Se investigó la incorporación en lugares B de pirocloro PMN de un exceso de Mg y un exceso de Nb. En el sistema Pb-Mg-Nb-O2 las composiciones analizadas fueron Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x donde x=0.1, 0.2, 0.3, 0.4, 0.522 y en Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x donde x= 0.1, 0.2,0.29. El exceso de Mg condujo a la formación de perovskita y el exceso de Nb resultó en la formación del pirocloro monolínico, Pb2Nb2O7. La densidad de la mezcla de PMN pirocloro-perovskita dismunuye con el aumento de la concentración de Mg. La permitividad dieléctrica de las mezclas aumenta con la disminución del contenido de pirocloro. El efecto del pirocloro sobre la permitividad sigue la regla de mezclas de Weiner hasta conenidos de pirocloro del 50%.

  5. Thermal, magnetic, and structural properties of soft magnetic FeCrNbCuSiB alloy ribbons

    International Nuclear Information System (INIS)

    Rosales-Rivera, A.; Valencia, V.H.; Quintero, D.L.; Pineda-Gomez, P.; Gomez, M.

    2006-01-01

    The thermal, magnetic and structural properties of amorphous magnetic Fe 73.5-x Cr x Nb 3 Cu 1 Si 13.5 B 9 alloy ribbons, with x=0, 2, 4, 6, 8, and 10, were studied by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magneto-impedance measurements and X-ray diffraction (XRD). The ribbons exhibit ultrasoft magnetic behavior, especially giant magneto-impedance effect, GMI. A three-peak behavior was observed in GMI curves. Particular attention has been given to observation of crystallization kinetics via DSC and TGA. The primary crystallization T pcr , and Curie T c , temperatures were determined from DSC and TGA data, respectively. The effect of partial substitution of iron by Cr on the thermal and magnetic properties is discussed

  6. [sup 57]Fe Moessbauer study of amorphous and nanocrystalline Fe[sub 73. 5]Nb[sub 3]Cu[sub 1]Si[sub 13. 5]B[sub 9] after neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, M. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Sitek, J. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Szasz, Z. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Vitazek, K. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia))

    1994-05-01

    [sup 57]Fe Moessbauer spectroscopy is used to study neutron irradiation induced changes in the short-range order of Fe[sub 73.5]Nb[sub 3]Cu[sub 1]Si[sub 13.5]B[sub 9] alloy. The samples are investigated in both amorphous and nanocrystalline states. Neutron irradiation leads to an increase of the standard deviation of a hyperfine field distribution (HFD), implying rearrangement of the atoms towards disordering. Simultaneously, changes in the average value of the hyperfine field and a net magnetic moment position occur as a consequence of a spin reorientation, atom mixing and microscopic stress centres which are introduced by neutron irradiation. (orig.)

  7. Hysteresis properties of conventionally annealed and Joule-heated nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloys

    International Nuclear Information System (INIS)

    Tiberto, P.; Basso, V.; Beatrice, C.; Bertotti, G.

    1996-01-01

    The dependence of magnetic properties on the thermal treatment used to induce the amorphous-to-nanocrystalline transformation in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloy has been studied. Quasi-static hysteresis loops and initial permeability measurements were performed on nanocrystalline samples obtained by conventional annealing and Joule heating. A comparison between the magnetic properties of nanocrystalline samples obtained by the two heating procedures is presented. (orig.)

  8. Effect of Hf underlayer on structure and magnetic properties of rapid thermal annealed FePt thin films

    International Nuclear Information System (INIS)

    Shen, C.Y.; Yuan, F.T.; Chang, H.W.; Lin, M.C.; Su, C.C.; Chang, S.T.; Wang, C.R.; Mei, J.K.; Hsiao, S.N.; Chen, C.C.; Shih, C.W.; Chang, W.C.

    2014-01-01

    FePt(20 nm) and FePt(20 nm)/Hf(10 nm) thin films prepared on the glass substrates by sputtering and post annealing are studied. For both samples, the as deposited films are disordered and L1 0 -ordering is triggered by a 400 °C-annealing. At T a ≥600 °C, Hf–Pt intermetallic compound forms with increasing T a , which consumes Pt in FePt layer and results in the formation of Fe 3 Pt phase. The film becomes soft magnetic at T a =800 °C. The optimized condition of FePt/Hf film is in the T a range of 500 to 600 °C where the interdiffusion between Hf and FePt layer is not extensive. The value of H c is 8.9 kOe and M r is 650–670 emu/cm 3 . Unlike FePt films, the Hf-undelayered samples show significantly reduced out-of-plane remanent and coercivity. The values for both are around 50% smaller than that of the FePt films. Additionally, Hf underlayer markedly reduces the FePt grain size and narrows the distribution, which enhances magnetic intergrain coupling. Good in-plane magnetic properties are preferred for the uses like a hard biasing magnet in a spintronic device. - Highlights: • Effect of Hf underlayer on structure and magnetic properties of FePt films are studied. • Hf underlayer reduces size, narrows the distribution of grains and thus enhances intergrain coupling. • Higher T a ≥600 °C makes Hf–Pt intermetallic compound and thus Fe 3 Pt phase form. • Good in-plane magnetic property is proper for uses in hard biasing magnet in spintronic devices

  9. Microstructural characterization of as-cast hf-b alloys

    Directory of Open Access Journals (Sweden)

    João Carlos Jânio Gigolotti

    2012-04-01

    Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

  10. Enhancement of plasticity of Fe-based bulk metallic glass by Ni substitution for Fe

    Energy Technology Data Exchange (ETDEWEB)

    Guo, S.F. [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Li, N.; Zhang, C. [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Liu, L., E-mail: sfguo2005@163.co [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)

    2010-08-15

    Bulk metallic glasses (BMGs) (Fe{sub 1-x}Ni{sub x}){sub 71}Mo{sub 5}P{sub 12}C{sub 10}B{sub 2} (x = 0, 0.1 and 0.2) with a diameter of 3 mm were synthesized by copper mold casting. The effect of Ni substitution for Fe on the structure, thermal and mechanical properties has been studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and compressive testing. It was found that the substitution of Ni for Fe enhances the glass forming ability, and improves the plasticity of Fe{sub 71}Mo{sub 5}P{sub 12}C{sub 10}B{sub 2} BMG as indicated by the increase in the plastic strain from 3.1% (x = 0) to 5.2% (x = 0.2). The improvement of the plasticity is discussed in term of the reduction of glass transition temperature and the supercooled liquid region due to the substitution of Ni for Fe.

  11. Study of the central region of the ternary diagram Zr-Nb-Fe, Part II

    International Nuclear Information System (INIS)

    Ramos, C; Saragovi, C; Arias, D; Granovsky, M

    2004-01-01

    This work continues with the identification and characterization of the intermetallic phases and of the two-phase and three-phase fields associated with the central region of the Zr-Nb-Fe phase diagram. In order to more precisely define the two-phase field βZr + λ 2 and to specify the range of existence in the zone with the highest Fe content for the λ2 phase, new alloys were smelted with the following nominal compositions: Zr 55 Nb 35 Fe 10 and Zr 35 Nb 5 Fe 60 . These alloys were submitted to a thermal treatment at 900 o C for 4 months. The techniques used to identify and characterize the phases in the samples were: optic metallography and electronic sweep, x-ray diffraction and Mossbauer spectroscopy. An isothermic cut of the central region for the Zr-Nb-Fe diagram is proposed considering previous results and those obtained in this work (Cw)

  12. Improved magnetoimpedance and mechanical properties on nanocrystallization of amorphous Fe68.5Si18.5Cu1Nb3B9 ribbons

    International Nuclear Information System (INIS)

    Sahoo, Trilochan; Majumdar, B.; Srinivas, V.; Srinivas, M.; Nath, T.K.; Agarwal, G.

    2013-01-01

    The effect of heat-treatment temperature on evolution of microstructures, mechanical and soft magnetic properties and magnetoimpedance (MI) effect in rapidly solidified Fe 68.5 Si 18.5 Cu 1 Nb 3 B 9 ribbons, has been investigated. The as-quenched ribbons were subjected to heat-treatment at different temperatures between 400 and 600 °C for 1 h under high vacuum. Detailed structural studies on the ribbons heat-treated at and above 525 °C revealed the presence of nanocrystalline Fe 3 Si phases embedded in a residual amorphous matrix. The ribbon heat-treated at 550 °C temperature exhibits maximum ductility, maximum relative permeability of 4.8×10 4 , minimum coercivity of 0.1 Oe, and maximum MI value of 62%. The enhanced MI effect is believed to be related to the magnetic softening of 550 °C heat-treated ribbons. However, the magnetic properties and MI effect deteriorated in the samples heat-treated above 550 °C due to the coarsening of grain sizes. The soft magnetic behavior of the nanocrystalline ribbons are discussed in the light of random anisotropy model, whereas the MI effect is discussed through standard skin effect in electrodynamics. - Highlights: • Microstructure was tuned by controlled crystallization to obtain superior magnetic properties. • Improved MI in the heat-treated ribbons is attributed to the superior electromagnetic properties. • Correlation between MI and magnetic properties of nc-Fe 68.5 Si 18.5 Cu 1 Nb 3 B 9 is established. • All the observed features are consistent with the proposed random anisotropy model

  13. Enhanced saturation magnetization of Fe3Si nanodot-embedded Fe80Si17Nb3 flexible film for efficient wireless power transfer

    International Nuclear Information System (INIS)

    Pai, Yi-Hao; Yan, Zih-Yu; Fu, Ping-Hao

    2013-01-01

    An efficient magnetically coupled resonance response is performed using an iron silicide-based nanostructured magnetoelectric material with high saturation magnetization for the wireless charging of battery-powered consumer electronics. With 500 °C annealing, the self-assembled Fe 3 Si nanodots buried in the Fe 80 Si 17 Nb 3 host matrix with (220) lattice spacing of 1.99 Å corresponding to a volume density of 8.96 × 10 16 cm 3 , can be obtained and a maximum saturation magnetization of 244 emu g −1 achieved. The return loss of the antenna will be tuned to match the designed frequency with greater attenuated intensity (−0.39 dB) and a relatively narrow bandwidth (6 kHz) when the Fe 3 Si nanodot-embedded Fe 80 Si 17 Nb 3 sample is placed in a WiTricity system. An efficient wireless power transfer can be created and improved from 47.5% to 97.3%. The associated coil and loop antenna resonators are significantly readjusted to match the power transfer by putting this nanostructured magnetoelectric material in a WiTricity system. - Highlights: • The saturation magnetization is effective enhancement in the presence of Fe 3 Si nanodot buried in the Fe 80 Si 17 Nb 3 . • A saturation magnetization of 244 emu g −1 is proposed for high-efficiency wireless power transfer. • The return loss of the antenna will be tuned to match the designed frequency. • Such a wireless power transfer can be enhanced efficiency up to 97.3%

  14. Analysis of sodium metal by X-ray fluorescence spectrometry (I). Determination of Hf, Mo, Nb, Ta, Ti, V and Zr

    International Nuclear Information System (INIS)

    Diaz-Guerra, J. P.

    1981-01-01

    A method allowing the determination of trace quantities of Hf, Mo, Nb, Ta, Ti, Vi and Zr in sodium metal previous transformation into Na 2 S0 4 is described. The enrichment of the impurities is performed through a coprecipitation technique in sulfuric medium by using Fe 3 + as a collector and cupferron or phenyfluorone as the precipitating reagent. The matrix influence and the best concentration of the collector (10/μ/ml), adequate pH (1,3 or 4, respectively) and optimum filter type (Millipore BSWP02500 or BDWP04700, respectively) have been studied, as well as the precipitation recoveries corresponding to the reagent above. It has been demonstrated the batter efficiency of the cupferron for determining all the Impurities. Detection limits range from 0.01 to 0.2 ppm., depending on the element, for samples 4 g in weight. An automatic spectrometer attached to a 16 K minicomputer and X-ray tube with a gold anode (2250-2700 W) are used. The Interferences between the lines ZrKα (2 n d order) - HfLα and TiKβ - VK α have been studied and the respective correction coefficients have been deduced. (Author) 8 refs

  15. Synthesis, magnetic properties and Moessbauer spectroscopy for the pyrochlore family Bi{sub 2}BB Prime O{sub 7} with B=Cr and Fe and B Prime =Nb, Ta and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Maria C. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Franco, Diego G. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Jalit, Yamile; Pannunzio Miner, Elisa V. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Berndt, Graciele; Paesano, Andrea [Departamento de Fisica, Universidade Estadual de Maringa, Parana (Brazil); Nieva, Gladys [Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Carbonio, Raul E., E-mail: carbonio@mail.fcq.unc.edu.ar [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina)

    2012-08-15

    The samples Bi{sub 2}BB Prime O{sub 7}, with B=Cr and Fe and B Prime =Nb, Ta and Sb were prepared by solid state method. The crystallographic structure was investigated on the basis of X-ray powder diffraction data. Rietveld refinements show that the crystal structure is cubic, space group Fd-3m. The Bi{sup 3+} cation on the eight-coordinate pyrochlore A-site shows displacive disorder, as a consequence of its lone pair electron configuration. There is also a considerable A-site disorder shown by Rietveld Analysis and confirmed in the case of the iron containing samples with Moessbauer spectroscopy. The magnetic measurements show paramagnetic behavior at all temperatures for the Cr oxides. The Fe pyrochlores show antiferromagnetic order around 10 K.

  16. Ideal solution behaviour of glassy Cu–Ti, Zr, Hf alloys and properties of amorphous copper

    International Nuclear Information System (INIS)

    Ristić, R.; Cooper, J.R.; Zadro, K.; Pajić, D.; Ivkov, J.; Babić, E.

    2015-01-01

    Highlights: • Ideal solution behaviour (ISB) is established in all Cu–Ti, Zr, Hf glassy alloys. • ISB enables reliable estimates for various properties of amorphous Cu. • ISB also impacts glass forming ability in these and probably other similar alloys. - Abstract: A comprehensive study of selected properties of amorphous (a) Cu–TE alloys (TE = Ti, Zr and Hf) has been performed. Data for average atomic volumes of a-Cu–Hf, Ti alloys combined with literature data show that ideal solution behaviour (Vegard’s law) extends over the whole glass forming range (GFR) in all a-Cu–TE alloys. This enables one to obtain an insight into some properties and probable atomic arrangements for both, a-TEs (Ristić et al., 2010) and a-Cu by extrapolation of the data for alloys. Indeed the atomic volumes and other properties studied for all a-Cu–TE alloys extrapolate to the same values for a-Cu. Depending on the property, these values are either close to those of crystalline (c) Cu, or are close to those for liquid (L) Cu. In particular, the electronic transport properties of a-Cu seem close to those of L-Cu, whereas the static properties, such as the density of states, and Young’s modulus, converge to those of c-Cu. The possible impact of these results on our understanding of a-Cu–TE alloys, including glass forming ability, is discussed

  17. Moessbauer spectroscopy of the Zr-rich region in Zr-Nb-Fe alloys with low Nb content

    International Nuclear Information System (INIS)

    Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

    1999-01-01

    Intermetallic phases and solid solutions in the Zr-rich region of the Zr-Nb-Fe system with low Nb content are studied by Moessbauer spectroscopy complemented with X-ray diffraction, optical and scanning electron microscopy and electron microprobe analysis. The phases found in each sample were those expected from the corresponding binary Zr-Fe system. Furthermore, one of the samples showed a ternary cubic Ti 2 Ni type phase with a similar stoichiometry to the tetragonal Zr 2 Fe compound. Moessbauer parameters were suggested to this phase (IS: - 0.12 mm/s, QS: 0.30 mm/s), to the bcc Zr(β) phase (IS: (-0.11 α 0.01) mm/s, QS: (0.23 α 0.02) mm/s), and to the hcp Zr(β T ) phase (IS: (-0.24 α 0.02) mm/s, QS: (0.45 α 0.02) mm/s)

  18. The improvement of the superconducting Y-Ba-Cu-O magnet characteristics through shape recovery strain of Fe-Mn-Si alloys

    International Nuclear Information System (INIS)

    Shimpo, Y.; Seki, H.; Wongsatanawarid, A.; Taniguchi, S.; Maruyama, T.; Kurita, T.; Murakami, M.

    2010-01-01

    Since bulk Y-Ba-Cu-O superconductors are brittle ceramics, reinforcement of mechanical properties is important for practical applications. It has been reported that bulk Y-Ba-Cu-O can be reinforced with Al or Fe based alloy ring, in that compression force acts on bulk Y-Ba-Cu-O due to a difference in thermal expansion coefficients. However, the shrinkage of the metal ring was not so large, and therefore careful adjustment of the circumference of the bulk and the metal rings was necessary. In this study, we employed Fe-Mn-Si shape memory alloy rings to reinforce bulk Y-Ba-Cu-O. The advantage of the shape memory alloy is that the shrinkage can take place on heating, and furthermore, the alloy shrinks and compresses the bulk body on cooling. Bulk Y-Ba-Cu-O superconductor 22.8 mm in diameter was inserted in a Fe-Mn-Si ring 23.0 mm in inner diameter at room temperature. Beforehand, the Fe-Mn-Si ring was expanded by 12% strain at room temperature. Then the composite was heated to 673 K. At room temperature, the Fe-Mn-Si ring firmly gripped the bulk superconductor. We then measured trapped fields before and after the ring reinforcement, and found that the trapped field was improved through the treatment.

  19. Glass formation of the Fe-Hf system studied by thermodynamic calculation and ion beam mixing

    International Nuclear Information System (INIS)

    Wang, T.L.; Wang, W.C.; Li, J.H.; Liu, B.X.

    2010-01-01

    For the Fe-Hf system characterized by a negative heat of formation, the glass-forming range/ability (GFR/GFA) was studied by thermodynamic calculation based on Miedema's model and Alonso's method. It was found that amorphous phase could be formed in a composition range of 24-86 atom% Hf and that alloy with composition of Fe 58 Hf 42 has the best GFA in the system. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe-Hf system. It turned out that in the samples with overall compositions located in the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation.

  20. Proton nuclear magnetic resonance studies of hydrogen diffusion and electron tunneling in Ni-Nb-Zr-H glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Niki, Haruo; Okuda, Hiroyuki; Oshiro, Morihito; Yogi, Mamoru [Department of Physics, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213 (Japan); Seki, Ichiro; Fukuhara, Mikio [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2012-06-15

    Using the Fourier transform of the echo envelope, the proton line shapes, spin-lattice relaxation time, and spin-spin relaxation time have been measured in a (Ni{sub 0.36}Nb{sub 0.24}Zr{sub 0.40}){sub 90}H{sub 10} glassy alloy at 1.83 T ({approx}78 MHz) and at temperatures between 1.8 and 300 K. First, the spectral line width decreases abruptly between 1.8 and 2.1 K. Next, it remains almost constant at 13 kHz up to {approx}150 K. Finally, the line width decreases as the temperature increases from {approx}150 to 300 K. The initial decrease in the spectral line width is ascribed to the distribution of the external field, which is caused by the penetration of vortices in the superconducting state. The subsequent leveling off in the spectral line width is ascribed to the dipole-dipole interaction between protons when hydrogen atoms are trapped into vacancies among the Zr-centered icosahedral Zr{sub 5}Ni{sub 5}Nb{sub 3} clusters. The final decrease in the spectral line width is ascribed to the motional narrowing of the width that is caused by the movement of hydrogen atoms. The temperature dependences of the spin-lattice and spin-spin relaxation time showed that at temperature above 150 K and the activation energy of 8.7 kJ/mol allowed the hydrogen atoms to migrate among the clusters. The distance between the hydrogen atoms is estimated to be 2.75 A. Hydrogen occupancies among clusters in the (Ni{sub 0.36}Nb{sub 0.24}Zr{sub 0.40}){sub 90}H{sub 10} glassy alloy play an important role in the diffusion behavior and in the electronic properties of this alloy.

  1. Ultra-soft magnetic Co-Fe-B-Si-Nb amorphous alloys for high frequency power applications

    Science.gov (United States)

    Ackland, Karl; Masood, Ansar; Kulkarni, Santosh; Stamenov, Plamen

    2018-05-01

    With the continuous shrinkage of the footprint of inductors and transformers in modern power supplies, higher flux, while still low-loss metallic replacements of traditional ferrite materials are becoming an intriguing alternative. One candidate replacement strategy is based on amorphous CoFeBSi soft-magnetic alloys, in their metallic glass form. Here the structural and magnetic properties of two different families of CoFeBSi-based soft magnetic alloys, prepared by arc-melting and subsequent melt spinning (rapid quenching) are presented, targeting potential applications at effective frequencies of 100 kHz and beyond. The nominal alloy compositions are Co67Fe4B11Si16Mo2 representing commercial Vitrovac and Co72-xFexB28-y (where B includes non-magnetic elements such as Boron, Silicon etc. x varies between 4 and 5 % and y is varied from 0 to 2 %) denoted Alloy #1 and prepared as a possible higher performance alternative, i.e. lower power loss and lower coercivity, to commercial Vitrovac. Room temperature magnetization measurements of the arc-melted alloys reveal that compared to Vitrovac, Alloy #1 already presents a ten-fold decrease in coercivity, with Hc ˜ 1.4 Am-1 and highest figure of merit of (Ms/Hc > 96). Upon melt-spinning the alloys into thin (< 30 μm) ribbons, the alloys are essentially amorphous when analyzed by XRD. Magnetization measurements of the melt-spun ribbons demonstrate that Alloy #1 possesses a coercivity of just 2 Am-1, which represents a significant improvement compared to melt-spun ribbons of Vitrovac (17 Am-1). A set of prototype transformers of approximately 10 turns of Alloy #1 ribbon exhibits systematically Hc < 10 Am-1 at 100 kHz, without a noticeable decrease in coupled flux and saturation.

  2. Initial stages of solid solution decomposition in Fe-Ti and Fe-Nb alloys

    International Nuclear Information System (INIS)

    Ustinovshchikov, Yu.I.; Chen Shiren; Shirobokova, M.S.

    1993-01-01

    Structural analysis of Fe-Ti and Fe-Nb systems is performed. Formation of Laves phases proceed through the stage of the formation of a structure representing a periodic sequence of the regions enriched and depleted in alloying element. Abnormal changes in the properties of alloys of the given systems are noted; there changes reside in a decrease of alloy hardness during the formation of the above structure

  3. Effect of solute atoms on glass-forming ability for Fe–Y–B alloy: An ab initio molecular dynamics study

    International Nuclear Information System (INIS)

    Han, J.J.; Wang, W.Y.; Liu, X.J.; Wang, C.P.; Hui, X.D.; Liu, Z.K.

    2014-01-01

    The glass-forming abilities of Fe 78 B 22 , Fe 70 Y 6 B 24 , Fe 72 Y 6 B 22 and Fe 72.5 Y 3.5 B 24 alloys were characterized comprehensively using ab initio molecular dynamics simulations. The calculated results were correlated with the properties and atomic structures. It was found that the Fe 72 Y 6 B 22 alloy consists of both the most stable and the least deformed body centered cubic atomic packing structures in the supercooled liquid and glassy states. It was observed that the local compositions in the Fe 72 Y 6 B 22 alloy significantly deviate from the compositions of stable crystalline phases, indicating that the Fe 72 Y 6 B 22 alloy has the best glass-forming ability among the alloys studied. However, Fe 72 Y 6 B 22 alloy has two flaws in terms of glass-forming ability, i.e. relatively large atomic diffusivity and insufficiently close atomic packing. The best performance in these two aspects is observed in the Fe 72.5 Y 3.5 B 24 alloy. Thus, the theoretical study predicts that the best glass former for the Fe–Y–B system is within the compositional range of 22–24 at.% B and 3.5–6 at.% Y

  4. Mechanical properties of nano and bulk Fe pillars using molecular dynamics and dislocation dynamics simulation

    Directory of Open Access Journals (Sweden)

    S. K. Deb Nath

    2017-10-01

    Full Text Available Using molecular dynamics simulation, tension and bending tests of a Fe nanopillar are carried out to obtain its Young’s modulus and yield strength. Then the comparative study of Young’s modulus and yield strength of a Fe nanopillar under bending and tension are carried out varying its diameter in the range of diameter 1-15nm. We find out the reasons why bending Young’s modulus and yield strength of a Fe nanopillar are higher than those of tension Young’s modulus and yield strength of a Fe nanopillar. Using the mobility parameters of bulk Fe from the experimental study [N. Urabe and J. Weertman, Materials Science and Engineering 18, 41 (1975], its temperature dependent stress-strain relationship, yield strength and strain hardening modulus are obtained from the dislocation dynamics simulations. Strain rate dependent yield strength and strain hardening modulus of bulk Fe pillars under tension are studied. Temperature dependent creep behaviors of bulk Fe pillars under tension are also studied. To verify the soundness of the present dislocation dynamics studies of the mechanical properties of bulk Fe pillars under tension, the stress vs. strain relationship and dislocation density vs. strain of bulk Fe pillars obtained by us are compared with the published results obtained by S. Queyreau, G. Monnet, and B. Devincre, International Journal of Plasticity 25, 361 (2009.

  5. Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

    Science.gov (United States)

    An, Jing; Song, Jinpeng; Liang, Guoxing; Gao, Jiaojiao; Xie, Juncai; Cao, Lei; Wang, Shiying; Lv, Ming

    2017-01-01

    The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure. PMID:28772821

  6. Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

    Directory of Open Access Journals (Sweden)

    Jing An

    2017-04-01

    Full Text Available The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure.

  7. Magnetic and Mössbauer studies of amorphous Fe 72- xY xHo 8B 20 alloys

    Science.gov (United States)

    Krishnan, R.; Driouch, L.; Lassri, H.; Dumond, Y.; Ajan, Antony; Shringi, S. N.; Prasad, Shiva

    1996-11-01

    We have carried out magnetic and Mössbauer studies of amorphous Fe 72- xY xHo 8B 20 alloys. The Fe moment decreases with the addition of Y and a magnetic compensation occurs at 4 K for x = 16. The temperature and field dependences of the magnetization have been interpreted using the mean field theory and Chudnovsky's model, respectively. These analyses yield some interesting parameters such as the random anisotropy, the exchange interactions JFe-Fe, JFe-Ho, etc. The Mössbauer studies show that the average hyperfine field decreases linearly with the addition of Y, in accordance with the decrease in the Fe moment.

  8. Analysis of the low-frequency magnetoelectric performance in three-phase laminate composites with Fe-based nanocrystalline ribbon

    International Nuclear Information System (INIS)

    Chen, Lei; Li, Ping; Wen, Yumei; Zhu, Yong

    2013-01-01

    The theoretical analysis of magnetoelectric (ME) performance in three-phase Terfenol-D/PZT/FeCuNbSiB (MPF) laminate composite is presented in this paper. The ME couplings at low frequency for ideal and less than ideal interface couplings are studied, respectively, and our analysis predicts that (i) the ME voltage coefficient for ideal interface coupling increases with the increasing layers (n) of Fe-based nanocrystalline ribbon FeCuNbSiB (Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ) while the sizes of PZT (Pb(Zr 1−x Ti x )O 3 ) and Terfenol-D (Tb 1−x Dy x Fe 2−y ) are kept constant, and then it tends to be a constant when the layers of FeCuNbSiB are >100; (ii) by introducing the interface coupling factor k and considering the degradation of d 33m,f with n, the ME voltage coefficient for a less than ideal interface condition is predicted. As the FeCuNbSiB layer increases, it first increases and reaches to a maximum value, and then slowly decreases. Various MPF laminates are fabricated and tested. It is found that the theoretical predictions for the consideration of actual boundary conditions at the interface are in agreement with the experimental observations. This study plays a guiding role for the design of MPF composite in real applications. (paper)

  9. Time effects and glassy state behaviour in superconducting Y1Ba2Cu3O7-x

    International Nuclear Information System (INIS)

    Altinkok, A.; Yetis, H.; Olutas, M.; Kilic, K.; Kilic, A.

    2007-01-01

    The quenched disorder in the moving entity is investigated in a polycrystalline bulk sample of Y 1 Ba 2 Cu 3 O 7-x (YBCO) by slow transport relaxation measurements (V-t curves) on long time scales. The time evolution of sample voltage (V-t curve) are correlated to spatial reorganization of the driving current together with increasing or decreasing of resistive and non-resistive flow channels in a multiple connected network. In addition, it is shown that the voltage decays appearing in V-t curves are characterized by an exponential time dependence which is analogous to the glassy state relaxation

  10. Thermal relaxation of magnetic clusters in amorphous Hf57Fe43 alloy

    International Nuclear Information System (INIS)

    Pajic, Damir; Zadro, Kreso; Ristic, Ramir; Zivkovic, Ivica; Skoko, Zeljko; Babic, Emil

    2007-01-01

    The magnetization processes in binary magnetic/non-magnetic amorphous alloy Hf 57 Fe 43 are investigated by the detailed measurement of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied by the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained by the superparamagnetic behaviour of the single domain magnetic clusters inside the non-magnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found that magnetic clusters occupy the characteristic volume from 25 up to 200 nm 3 . The validity of the superparamagnetic model of Hf 57 Fe 43 is based on the concentration of iron in the Hf 100-x Fe x system that is just below the threshold for long range magnetic ordering. This work also throws more light on the magnetic behaviour of other amorphous alloys

  11. Magnetic domain size effect on resistivity and Hall effect of amorphous Fe83-xZr7B10Mx (M=Ni, Nb) alloys

    International Nuclear Information System (INIS)

    Rhie, K.; Lim, W.Y.; Lee, S.H.; Yu, S.C.

    1997-01-01

    Studies of effective permeability, core loss and saturation magnetostriction of Fe 83-x Zr 7 B 10 M x (M=Ni, Nb) alloys revealed that the domain width is smallest around x=0.10. We measured the resistivity and low field Hall coefficients of these alloys and found that the maxima of resistivity and Hall coefficients occurred roughly at the same concentrations. Larger surface area of smaller domains is considered the reason. copyright 1997 American Institute of Physics

  12. Effect of heat treatment on Fe-B-Si-Nb alloy powder prepared by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Rodrigo Estevam Coelho

    2005-06-01

    Full Text Available The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA and for different milling times (1, 5, 25, 70 and 100 hours. Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm. The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.

  13. Structural Transformation in Fe73.5Nb3Cu1Si15.5B7 Amorphous Alloy Induced by Laser Heating

    Science.gov (United States)

    Nykyruy, Yu. S.; Mudry, S. I.; Kulyk, Yu. O.; Zhovneruk, S. V.

    2018-03-01

    The effect of continuous laser irradiation (λ = 1.06 μm) with laser power of 45 W on the structure of Fe73.5Nb3Cu1Si15.5B7 amorphous alloy has been studied using X-ray diffraction and SEM methods. The sample of the ribbon has been placed at a distance from the focal plane of the lens, so a laser beam has been defocused and the diameter of laser spot on the ribbon surface has been about 10 mm. An exposure time τ varied within interval 0.25-0.70 s. Under such conditions structural transformation processes, which depend on the exposure time, have occurred in an irradiated zone. Crystallization process has started at τ = 0.35 s with the formation of α-Fe(Si) nanocrystalline phase, while complete crystallization has occurred at τ = 0.55 s with formation of two nanocrystalline phases: α-Fe(Si) and a hexagonal H-phase.

  14. Moessbauer spectroscopy of the Zr-rich region in Zr-Nb-Fe alloys with low Nb content

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, C. [Universidad de Buenos, Facultad de Ciencias Exactas y Naturales (Argentina); Saragovi, C. [Departamento de Fisica, Comision Nacional de Energia Atomica (Argentina); Granovsky, M.; Arias, D. [Departamento de Materiales, Comision Nacional de Energia Atomica (Argentina)

    1999-11-15

    Intermetallic phases and solid solutions in the Zr-rich region of the Zr-Nb-Fe system with low Nb content are studied by Moessbauer spectroscopy complemented with X-ray diffraction, optical and scanning electron microscopy and electron microprobe analysis. The phases found in each sample were those expected from the corresponding binary Zr-Fe system. Furthermore, one of the samples showed a ternary cubic Ti{sub 2}Ni type phase with a similar stoichiometry to the tetragonal Zr{sub 2}Fe compound. Moessbauer parameters were suggested to this phase (IS: - 0.12 mm/s, QS: 0.30 mm/s), to the bcc Zr({beta}) phase (IS: (-0.11 {alpha} 0.01) mm/s, QS: (0.23 {alpha} 0.02) mm/s), and to the hcp Zr({beta}{sup T}) phase (IS: (-0.24 {alpha} 0.02) mm/s, QS: (0.45 {alpha} 0.02) mm/s)

  15. Influence of the spin reorientation transition on the hysteresis characteristics of Nd-Fe-B film and bulk magnets

    International Nuclear Information System (INIS)

    Lileev, A.S.; Parilov, A.A.; Reissner, M.; Steiner, W.

    2004-01-01

    A comparison was made of the hysteresis characteristics of hard magnetic films with those of bulk samples based on Nd 2 Fe 14 B in the temperature range between 4.2 and 293 K. In both types of specimens characteristic 'dips' appear below 135 K in the demagnetisation curves which are caused by both the spin reorientation from easy axis to easy cone and the deviation from a perfect texture of the sample

  16. Solution chemistry of element 105. Pt. III. Hydrolysis and complex formation of Nb, Ta, Db and Pa in HF and HBr solutions

    International Nuclear Information System (INIS)

    Pershina, V.; Bastug, T.

    1999-01-01

    Calculations of the electronic structure of MF 6 - and MBr 6 - complexes of Nb, Ta, Pa and element 105, Db, formed in HF and HBr solutions have been performed using the Dirac-Slater Discrete Variational method. On the basis of results of these calculations, relative values of the free energy change of reactions of complex formation have been determined. The order of the complex formation for both acids is shown to be Pa >> Nb > Db > Ta. Such a sequence is defined by a predominant electrostatic energy of the metal-ligand interaction. The hydrolysis of compounds, as a reverse process, proved to change as Ta > Db > Nb >> Pa. Using the theory of metal extraction by anion exchange, the following trend in the extraction of the anionic species from both the HF and HBr aqueous solutions has been predicted: Pa >> Nb ≥ Db > Ta. The strength of the ML 6 - complexes is shown to decrease from MF 6 , to MCl 6 and further to MBr 6 - which is reflected by shifting the complex formation process to the area of higher acid concentrations. (orig.)

  17. Magnetic and Structural Properties of the Mechanically Alloyed Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B System

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, D. Oyola, E-mail: doyola@ut.edu.co [University of Tolima, Department of Physics (Colombia); Zamora, L. E.; Perez Alcazar, G. A. [University of Valle, Department of Physics (Colombia); Rojas, Y. A.; Bustos, H. [University of Tolima, Department of Physics (Colombia); Greneche, J. M. [UMR CNRS 6087, Laboratoire de Physique de l' Etat Condense (France)

    2005-02-15

    In this work we report the magnetic and structural properties obtained by Moessbauer spectrometry, Vibrating Sample Magnetometer and X-ray diffraction of milled powders with initial composition Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B with x = 0 and x = 4. The mixtures were ball milled for different times up to 240 h. Structural and microstructural parameters were derived from high statistics X-ray patterns and discussed as a function of milling time. The Moessbauer spectra of the samples were fitted by means of a sextet and an hyperfine field distribution, associated to a pure iron phase ({alpha}-Fe) and a disordered iron-based phase, respectively. The {alpha}-Fe grain size decreases from 50 nm for 6 h up to 5 nm for 240 h milling time. The Vibrating Sample Magnetometer results allow to conclude that these samples behave as soft ferromagnets.

  18. Theoretical study of phase stability and elastic properties of T0.75Y0.75B14 (T  =  Sc, Ti, V, Y, Zr, Nb, Si)

    International Nuclear Information System (INIS)

    Hunold, Oliver; Music, Denis; Schneider, Jochen M

    2016-01-01

    In this study the phase stability, elastic properties, and plastic behaviour of icosahedral transition metal borides T 0.75 Y 0.75 B 14 (T  =  Sc, Ti, V, Y, Zr, Nb, Si) have been investigated using density functional theory. Phase stability critically depends on the charge transferred by T and Y to the B icosahedra. For the metal sublattice occupancy investigated here, the minimum energy of formation is identified at an effective B icosahedra charge of  −1.8  ±  0.1. This charge corridor encompasses the highest phase stability among all the reported icosahedral transition metal boride systems so far. This data provides guidance for future experimental efforts: from a wear-resistance point of view, Sc 0.75 Y 0.75 B 14 , Ti 0.75 Y 0.75 B 14 , and Zr 0.75 Y 0.75 B 14 exhibit a rather unique and attractive combination of large Young’s modulus values ranging from 488 to 514 GPa with the highest phase stability for icosahedral transition metals borides reported so far. (paper)

  19. The Effect of Nb Addition on the Microstructure and the High-Temperature Strength of Fe3Al Aluminide

    Science.gov (United States)

    Kratochvíl, Petr; Švec, Martin; Král, Robert; Veselý, Jozef; Lukáč, Pavel; Vlasák, Tomáš

    2018-02-01

    The microstructural and high-temperature mechanical properties of Fe-26Al-xNb (x = 3 and 5 at. pct) are compared. The alloys were investigated "as cast" and after hot rolling at 1473 K (1200 °C). Scanning electron microscopes equipped with EDS and EBSD were used for the microstructure and phase identification. The addition of 3 at. pct of Nb into the Fe3Al matrix leads to the formation of C14 λ—Laves phase (Fe,Al)2Nb (LP) particles spread in the Fe3Al matrix, while an eutectic with thin lamellae of LP C14 λ—Laves phase (Fe,Al)2Nb and matrix is also formed in the iron aluminide with 5 at. pct of Nb. The presence of incoherent precipitates is connected with the enhancement of the high-temperature strength and creep resistance.

  20. Numerical evaluation of guidance force decay of HTS bulk exposed to AC magnetic field over a NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Longcai [P.O. Box 152, Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: zhlcai2000@163.com; Wang Jiasu; Wang Suyu; Zheng Jun; He Qingyong [P.O. Box 152, Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2007-12-01

    The guidance force of the YBCO bulk over a NdFeB guideway used in the high-temperature superconducting maglev vehicle system was decayed by the application of the AC external magnetic field. In our previous work, we explained that the decay was due to the temperature rise of the HTS bulk caused by AC losses. In this paper, we adopted an analytic model to evaluate the decay of the critical current density of the bulk. And based on the analytic results and the Bean critical-state model, we calculated the guidance force as a function of times. Compared with the experimental results, the calculation results have almost the same trend and can qualitatively reveal the characteristics of guidance force of HTS bulk in this situation. Therefore, the guidance force decay of HTS bulk in the maglev vehicle system can be evaluated simply by this numerical method.

  1. Moessbauer spectroscopy on amorphous Fe/sub x/Ni/sub 80-x/B20 after neutron irradiation

    International Nuclear Information System (INIS)

    Sitek, J.; Miglierini, M.

    1985-01-01

    Amorphous Fe/sub x/Ni/sub 80-x/B 20 glassy alloys (x = 40, 50, 60, and 70) irradiated with fast neutrons in a fluence range of 10 14 to 10 19 cm -2 were investigated by Moessbauer spectroscopy. There were some significant changes in the Moessbauer spectrum parameters of the 10 19 cm -2 irradiated samples except Fe 40 Ni 40 B 20 . This corresponds to a change in the direction of the easy axis of magnetization. The measurements show that the resistance of the Fe-Ni-B system against neutron irradiation improves with increasing Ni content up to a certain point

  2. Fe substitution and pressure effects on superconductor Re6Hf

    Science.gov (United States)

    Yang, Jinhu; Guo, Yang; Wang, Hangdong; Chen, Bin

    2018-04-01

    Polycrystalline samples of (Re1-xFex) 6Hf were synthesized by arc-melting method and the phase purity of the samples was confirmed by powder X-ray diffraction method. In this paper, we report the Fe substitution and pressure effect on non-centrosymmetric superconductor Re6Hf. The superconducting transition temperature, TC, is confirmed by the measurements of magnetic susceptibility, electrical resistivity for x ≤ 0.22 samples with the temperature down to 2 K. We find that the TC is suppressed with the increase of Fe content. The upper critical field Hc2 is larger than the value predicted by the WHH theory and shows a linear temperature dependence down to 2 K. When upon the application of external pressure up to 2.5 GPa, the TC decreases monotonically at a rate dlnTC/dP of 0.01 GPa-1.

  3. Fe-based bulk amorphous alloys with iron contents as high as 82 at%

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jin-Feng; Liu, Xue; Zhao, Shao-Fan; Ding, Hong-Yu [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yao, Ke-Fu, E-mail: kfyao@tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-07-15

    Fe-based bulk amorphous alloys (BAAs) with high Fe contents are advantageous due to their high saturation magnetization and low cost. However, preparing Fe-based BAAs with Fe contents higher than 80 at% is difficult due to their poor glass forming abilities (GFA). In this study, an Fe{sub 81}P{sub 8.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA with a diameter of 1 mm and a saturation magnetization of 1.56 T was successfully prepared using the fluxing and copper mold casting methods. In addition, by introducing a small amount of elemental Mo to the alloy, an Fe{sub 82}Mo{sub 1}P{sub 6.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA rod with a diameter of 1 mm, a high saturation magnetization of 1.59 T, a high yield stress of 3265 MPa, and a clear plasticity of 1.3% was prepared in the same way. The cost effectiveness and good magnetic properties of these newly-developed Fe-based BAAs with Fe contents as high as 82 at% would be advantageous and promising for industrial applications. - Highlights: • Novel Fe-based BAA with no other metallic element except 81 at% Fe was prepared. • Fe-based bulk amorphous alloy (BAA) with the highest Fe content (82%) was prepared. • Very high saturation magnetization of 1.59 T has been achieved. • A new thought for designing Fe-based BAA with high Fe content was provided.

  4. Nonvolatile two-step, two-color holography with continuous-wave lights for both congruent and near-stoichiometric LiNbO3:Fe

    International Nuclear Information System (INIS)

    Shen Yan; Zhang Guoquan; Fu Bo; Xu Qingjun; Xu Jingjun

    2004-01-01

    We have studied theoretically the steady-state nonvolatile two-step, two-color holographic recording performance for both the congruent and the near-stoichiometric LiNbO 3 :Fe based on the two-center model (the deep-trap and the shallow-trap centers are Fe 2+ /Fe 3+ and Nb Li 4+ /Nb Li 5+ , respectively). The results show that the direct electron exchange between the Fe 2+ /Fe 3+ centers and the Nb Li 4+ /Nb Li 5+ centers due to the tunneling effect dominates the charge-transfer process during the nonvolatile two-step, two-color holography and determines the two-step, two-color holography performance in LiNbO 3 :Fe. We have further studied the effects of the crystal stoichiometry on the performance of the two-step, two-color holography. It is shown that, as far as the total space-charge field is considered, the nonvolatile two-step, two-color holography performance in the near-stoichiometric LiNbO 3 :Fe is much better than that in the congruent LiNbO 3 :Fe within the intensity range reachable by the continuous-wave lights

  5. 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)

  6. Short-range ferromagnetism in alloy ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    THANH, P. Q.; HOA, N. Q.; CHAU, N. [Vietnam National University, Hanoi (Viet Nam); HUU, C. X. [Danang University of Technology, Danang (Viet Nam); NGO, D. T. [Technical University of Denmark, Kgs. Lyngby (Denmark); PHAN, T. L. [Chungbuk National University, Cheongju (Korea, Republic of)

    2014-04-15

    We have studied the magnetic properties of two amorphous alloy ribbons Fe{sub 72}Cr{sub 6}Si{sub 4}Nb{sub 5}B{sub 12}Ag{sub 1} (FCSNB-Ag) and Fe{sub 72}Cr{sub 6}Si{sub 4}Nb{sub 5}B{sub 12}Cu{sub 1} (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization (M) measurements for various temperatures (T) and magnetic fields (H) indicate that ferromagnetic-paramagnetic (FM-PM) phase transitions take place in FCSNB-Ag and FCSNB-Cu at Curie temperatures (T{sub C} ) of about 308.3 K and 322.5 K, respectively. Analyses of M - H data at different temperatures in the vicinity of the FM-PM phase transition based on the modified Arrott plot method and scaling hypothesis yielded the exponent values of β = 0.369 ± 0.005, γ = 1.359 ± 0.005 and δ = 4.7 ± 0.1 for FCSNB-Ag, and β = 0.376 ± 0.002, γ = 1.315 ± 0.006 and δ = 4.5 ± 0.1 for FCSNB-Cu. Compared with the values from theoretical models, these values are close to those expected for the 3D Heisenberg model, demonstrating the existence of short-range FM order in the amorphous alloy ribbons.

  7. NdFeB nanoparticles prepared by wet-milling

    Energy Technology Data Exchange (ETDEWEB)

    Thielsch, Juliane; Lyubina, Julia; Woodcock, Thomas; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden (Germany)

    2010-07-01

    Since the prediction of a giant energy product of textured nanocomposite magnets those materials where believed to be the next generation of permanent magnets. For effective exchange-coupling in such two-phase magnets grain sizes need to be in the range of the domain wall width of the hard magnetic phase. That makes a homogenous phase distribution and a microstructure with nanograins necessary. One option of preparing such materials is the synthesis of magnetic nanoparticles which further could be aligned and compacted to a bulk magnet. For this we performed wet-milling experiments of a NdFeGaNbB alloy. XRD studies revealed that by using a surfactant and a solvent during the high energy ball milling process amorphization sets in later than compared to dry milling experiments under the same conditions. Dynamic Light Scattering investigations showed a Gauss distribution of the particle size with a mean diameter of about 12nm which was also proven by TEM. Magnetic properties were measured with SQUID and showed so far rather poor coercivity values.

  8. The influence of Zr substitution for Nb on the corrosion behaviors of the Ni-Nb-Zr bulk metallic glasses

    Science.gov (United States)

    Li, DengKe; Zhu, ZhengWang; Zhang, HaiFeng; Wang, AiMin; Hu, ZhuangQi

    2012-12-01

    The influence of Zr content on corrosion behaviors of the Ni61.5Nb38.5- x Zr x ( x=1, 3, 5, 7, 9 at.%) bulk metallic glasses (BMGs) in 1 M HCl aqueous solution was investigated by potentiodynamic polarization measurements and X-ray photo-electron spectroscopy (XPS). It was found that these BMG alloys possess superior corrosion resistance, that is, with large passive region of about 1.5 V and low passive current density (as low as 0.05 Am-2 for Ni61.5Nb31.5Zr7). XPS analysis indicates that the high corrosion resistance is attributed to the formation of Nb- and Zr-enriched surface films formed in the aggressive acid solution. The Zr substitution for Nb effectively reduces the Ni content, particularly the metallic state Ni content in the surface films, which depresses the electrical conduction of the surface films and reduces the passive current density, thus leading to the enhancement of the corrosion resistance of these Ni-Nb-Zr BMGs. These alloys may potentially be useful for engineering applications.

  9. Carbothermic reduction behaviors of Ti-Nb-bearing Fe concentrate from Bayan Obo ore in China

    Science.gov (United States)

    Wang, Guang; Du, Ya-xing; Wang, Jing-song; Xue, Qing-guo

    2018-01-01

    To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti-Nb-bearing Fe concentrate/coal composite pellet was reduced at temperatures greater than 1100°C. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100°C were analyzed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100°C for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.

  10. Design of Novel Precipitate-Strengthened Al-Co-Cr-Fe-Nb-Ni High-Entropy Superalloys

    Science.gov (United States)

    Antonov, Stoichko; Detrois, Martin; Tin, Sammy

    2018-01-01

    A series of non-equiatomic Al-Co-Cr-Fe-Nb-Ni high-entropy alloys, with varying levels of Co, Nb and Fe, were investigated in an effort to obtain microstructures similar to conventional Ni-based superalloys. Elevated levels of Co were observed to significantly decrease the solvus temperature of the γ' precipitates. Both Nb and Co in excessive concentrations promoted the formation of Laves and NiAl phases that formed either during solidification and remained undissolved during homogenization or upon high-temperature aging. Lowering the content of Nb, Co, or Fe prevented the formation of the eutectic type Laves. In addition, lowering the Co content resulted in a higher number density and volume fraction of the γ' precipitates, while increasing the Fe content led to the destabilization of the γ' precipitates. Various aging treatments were performed which led to different size distributions of the strengthening phase. Results from the microstructural characterization and hardness property assessments of these high-entropy alloys were compared to a commercial, high-strength Ni-based superalloy RR1000. Potentially, precipitation-strengthened high-entropy alloys could find applications replacing Ni-based superalloys as structural materials in power generation applications.

  11. Mechanical properties and bio-tribological behaviors of novel beta-Zr-type Zr-Al-Fe-Nb alloys for biomedical applications.

    Science.gov (United States)

    Hua, Nengbin; Chen, Wenzhe; Zhang, Lei; Li, Guanghui; Liao, Zhenlong; Lin, Yan

    2017-07-01

    The present study prepares novel Zr 70+x Al 5 Fe 15-x Nb 10 (x=0, 5) alloys by arc-melting for potential biomedical application. The mechanical properties and bio-tribological behaviors of the Zr-based alloys are evaluated and compared with biomedical pure Zr. The as-prepared alloys exhibit a microstructure containing a micrometer-sized dendritic beta-Zr phase dispersed in a Zr 2 Fe-typed matrix. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high compressive strength. The wear resistance of the Zr-Al-Fe-Nb alloys in air and phosphate buffer saline (PBS) solution is superior to that of pure Zr. The wear mechanism of Zr-based alloys sliding in air is controlled by oxidation and abrasive wear whereas that sliding in PBS is controlled by synergistic effects of the abrasive and corrosive wear. Electrochemical measurements demonstrate that the Zr-based alloys are corrosion resistant in PBS. Their bio-corrosion resistance is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. The Zr 75 Al 5 Fe 10 Nb 10 exhibits the best corrosion resistance in PBS, which contributes to its superior wear resistance in a simulated body environment. The combination of good mechanical properties, corrosion resistance, and biotribological behaviors of the Zr-Al-Fe-Nb alloys offers them potential advantages in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Inhomogeneity of surface magnetic field over a NdFeB guideway and its influence on levitation force of the HTS bulk maglev system

    International Nuclear Information System (INIS)

    Zhang, Longcai; Wang Jiasu; He Qingyong; Zhang Jianghua; Wang Suyu

    2007-01-01

    Superconducting maglev vehicle system was one of the most promising applications of HTS bulks. The NdFeB guideway in this system was composed of many NdFeB permanent magnets and screws, so the air gaps (airgaps) between two permanent magnets and the screws would result in the inhomogeneity of the surface magnetic field. In this paper, we studied the magnetic inhomogeneity over the permanent magnet guideway (PMG) used in high-temperature superconducting (HTS) maglev vehicle system and its influence on the levitation force of the HTS bulk. Firstly, we measured the transverse magnetic field above the airgap, the screw and the place under where there was no airgap and screw. It was found that the magnetic field 10 mm above the guideway was roughly uniform. Secondly, we investigated the influence of the magnetic inhomogeneity of the PMG on levitation force of the bulk superconductor. From the experiment results, we found that the influence was very small, and would be ignored. Therefore, we could conclude that the PMG made by this method satisfied the requirements of the HTS maglev vehicle system in a quasi-static state

  13. Inhomogeneity of surface magnetic field over a NdFeB guideway and its influence on levitation force of the HTS bulk maglev system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Longcai [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China)]. E-mail: zhlcai2000@163.com; Wang Jiasu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); He Qingyong [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); Zhang Jianghua [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China); Wang Suyu [Applied Superconductivity Laboratory, Southwest Jiaotong University, P.O. Box 152, Chengdu 610031 (China)

    2007-08-01

    Superconducting maglev vehicle system was one of the most promising applications of HTS bulks. The NdFeB guideway in this system was composed of many NdFeB permanent magnets and screws, so the air gaps (airgaps) between two permanent magnets and the screws would result in the inhomogeneity of the surface magnetic field. In this paper, we studied the magnetic inhomogeneity over the permanent magnet guideway (PMG) used in high-temperature superconducting (HTS) maglev vehicle system and its influence on the levitation force of the HTS bulk. Firstly, we measured the transverse magnetic field above the airgap, the screw and the place under where there was no airgap and screw. It was found that the magnetic field 10 mm above the guideway was roughly uniform. Secondly, we investigated the influence of the magnetic inhomogeneity of the PMG on levitation force of the bulk superconductor. From the experiment results, we found that the influence was very small, and would be ignored. Therefore, we could conclude that the PMG made by this method satisfied the requirements of the HTS maglev vehicle system in a quasi-static state.

  14. Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires

    International Nuclear Information System (INIS)

    Borza, F.; Lupu, N.; Dobrea, V.; Chiriac, H.

    2015-01-01

    Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems

  15. Effect of B and B + Nb on the bainitic transformation in low carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Kangying, E-mail: kangying.zhu@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, BP 30320, 57283 Maizieres-les-Metz Cedex (France); Oberbillig, Carla, E-mail: carla.oberbillig@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, BP 30320, 57283 Maizieres-les-Metz Cedex (France); Musik, Celine, E-mail: celine.musik@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, BP 30320, 57283 Maizieres-les-Metz Cedex (France); Loison, Didier, E-mail: didier.loison@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, BP 30320, 57283 Maizieres-les-Metz Cedex (France); Iung, Thierry, E-mail: thierry.iung@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, BP 30320, 57283 Maizieres-les-Metz Cedex (France)

    2011-05-15

    Research highlights: {yields} B retards slightly the bainite transformation kinetics. {yields} Combined addition of B + Nb delayed dramatically bainite transformation kinetics. {yields} B refines the microstructure and promotes lath morphology of bainite. {yields} Larger packets of laths and longer laths are observed in the B + Nb steel. {yields} More free boron/finer borocarbide precipitates on {gamma} grain boundaries in B + Nb steel. - Abstract: Development of new, advanced high and ultra-high strength bainitic steels requires the selection of the optimum balance of bainite promoting elements allowing the production of the desired bainitic microstructure over a wide range of cooling rates. The addition of boron or a combined addition of boron and niobium is well known to retard strongly the polygonal ferrite formation but very little knowledge has been acquired on the bainitic transformation. Therefore, the purpose of this study is to investigate the influence of boron and boron plus niobium on the bainite transformation kinetics, microstructural evolution and mechanical properties in a low carbon steel (Fe-0.05C-1.49Mn-0.30Si). Isothermal and continuous cooling transformation diagrams were determined and followed by a detailed quantitative characterisation of the bainite microstructure and morphology using complementary advanced metallographic techniques (FEG-SEM-EBSD, SIMS and TEM). The relationship between microstructure and hardness has been evaluated. Finally, results of SIMS and TEM analyses coupled with microstructural investigations enable to propose a mechanism to explain the effect of the synergy between boron and niobium on the bainitic transformation and the resultant microstructure.

  16. Effect of B and B + Nb on the bainitic transformation in low carbon steels

    International Nuclear Information System (INIS)

    Zhu Kangying; Oberbillig, Carla; Musik, Celine; Loison, Didier; Iung, Thierry

    2011-01-01

    Research highlights: → B retards slightly the bainite transformation kinetics. → Combined addition of B + Nb delayed dramatically bainite transformation kinetics. → B refines the microstructure and promotes lath morphology of bainite. → Larger packets of laths and longer laths are observed in the B + Nb steel. → More free boron/finer borocarbide precipitates on γ grain boundaries in B + Nb steel. - Abstract: Development of new, advanced high and ultra-high strength bainitic steels requires the selection of the optimum balance of bainite promoting elements allowing the production of the desired bainitic microstructure over a wide range of cooling rates. The addition of boron or a combined addition of boron and niobium is well known to retard strongly the polygonal ferrite formation but very little knowledge has been acquired on the bainitic transformation. Therefore, the purpose of this study is to investigate the influence of boron and boron plus niobium on the bainite transformation kinetics, microstructural evolution and mechanical properties in a low carbon steel (Fe-0.05C-1.49Mn-0.30Si). Isothermal and continuous cooling transformation diagrams were determined and followed by a detailed quantitative characterisation of the bainite microstructure and morphology using complementary advanced metallographic techniques (FEG-SEM-EBSD, SIMS and TEM). The relationship between microstructure and hardness has been evaluated. Finally, results of SIMS and TEM analyses coupled with microstructural investigations enable to propose a mechanism to explain the effect of the synergy between boron and niobium on the bainitic transformation and the resultant microstructure.

  17. A structural, magnetic, and Mössbauer study of the Dy{sub 2}Fe{sub 17−x}Nb{sub x} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Rai, B.K. [Department of Physics, The University of Memphis, Memphis, TN 38152 (United States); Syed Ali, K.S. [Department of Science, Estill High school, Estill, SC 29918 (United States); Mishra, S.R., E-mail: srmishra@memphis.edu [Department of Physics, The University of Memphis, Memphis, TN 38152 (United States); Khanra, S.; Ghosh, K. [Department of Physics, Astronomy, and Materials Science, The Missouri State University, Springfield, MO 65897 (United States)

    2014-03-15

    The single-phase intermetallic compounds of refractory metal Nb doped Dy{sub 2}Fe{sub 17−x}Nb{sub x} were prepared by arc melting. The substitution of Nb in the Dy{sub 2}Fe{sub 17} compound was found to have an important effect on their structure and magnetic properties. The Rietveld analysis of X-ray diffraction data shows that Dy{sub 2}Fe{sub 17−x}Nb{sub x} (x=0–1.5) solid solutions crystallize with the Th{sub 2}Ni{sub 17} structure. The lattice parameters obtained from Rietveld refinement show that the unit cell volume of Dy{sub 2}Fe{sub 17−x}Nb{sub x} increases linearly with increasing Nb concentration up to x=1. The solubility of Nb was found to be limited to x∼1. The substitutional Nb atoms occupied all four sites in the order 12j>12k>6g>4f of a Th{sub 2}Ni{sub 17} structure. The Curie temperature (T{sub c}) was found to be Nb content dependent. The T{sub c} first increased and then decreased with increasing Nb content x, attaining a maximum value of 460 K at around x=1, which is 78 K higher than that of Dy{sub 2}Fe{sub 17}. The saturation magnetization decreased linearly with increasing Nb content from 69 emu/g for x=0 to 38 emu/g for x=1.5. {sup 57}Fe Mössbauer spectra show the presence of DyFe{sub 3} and NbFe{sub 2} phases at a higher Nb content x≥1. The hyperfine field values of 4f site first increased up to x=1 and then decreased at higher Nb content. - Highlights: • Nb is used to suppress the free alpha iron in 2:17 intermediates. At higher concentration x>1, Nb forms paramagnetic phase with alpha iron, NbFe{sub 2}. • The low level of Nb doping (x<1) in Dy{sub 2}Fe{sub 17−x}Nb{sub x} brings in ∼21% increase in the Curie temperature. • In Al, Si or Ga doped 2:17 intermatallics, similar improvement is observed in T{sub c} at a much higher doping concentration at the cost of reduction in net magnetization. • The maximum Curie temperature, 460 K, is observed for x∼1 Nb doping.

  18. Structural characterization of Mg substituted on A/B sites in NiFe_2O_4 nanoparticles using autocombustion method

    Science.gov (United States)

    De, Manojit; Tewari, H. S.

    2017-07-01

    In the present paper, we are reporting the synthesis of pure nickel and magnesium ferrite [NiFe_2O_4, MgFe_2O_4] and magnesium-substituted nickel ferrite (Ni_{1-x}Mg_{x/y}Fe_{2-y}O_4; x=y=0.60) on A/B sites with particles size in nanometer range using autocombustion technique. In this study, it has been observed that with increase in sintering temperature, the estimated bulk density of the materials increases. The XRD patterns of the samples show the formation of single-phase materials and the lattice parameters are estimated from XRD patterns. From Raman spectra, the Raman shift of pure NiFe_2O_4 and MgFe_2O_4 are comparable with the experimental values reported in literature. The Raman spectra give five Raman active modes (A_{{1g}} + Eg + 3F_{2g}) which are expected in the spinel structure.

  19. Studies of structural and magnetic properties of glass-coated nanocrystalline Fe79Hf7B12Si2 microwires

    International Nuclear Information System (INIS)

    Garcia, C.; Zhukov, A.; Gonzalez, J.; Zhukova, V.; Varga, R.; Val, J.J. del; Larin, V.; Blanco, J.M.

    2006-01-01

    In the present work we deal with the fabrication of thin of Fe 79 Hf 7 B 12 Si 2 (low Si content) glass-coated microwire with a nanocrystalline structure and structural and coercivity characterization of such samples which can be considered as a new family of these nanocrystalline materials. Pieces of 10 cm of this microwire were annealed (300-600 deg. C during 1 h). The structural characteristics of the as-cast and annealed samples were determined, at room temperature, by X-ray diffraction (XRD) technique. XRD measurements allow to obtain the evolution of the grain size (15-35 nm) and relative volume fraction (5-60%) of the nanograins as a function of he annealing temperature in the annealed samples. Coercive field (H c ) of the as-cast and annealed samples has been evaluated from the hysteresis loop of the samples obtained by a conventional induction method at 100 Hz. Thermal dependence H c is quite similar to that reported in other nanocrystalline Fe-based alloys. It slightly decreases from the as-cast state (relaxation process) showing small maximum at around 700 K (pre-nucleation of nanograins) decreasing significantly between 773-873 K (exchange coupling of the nanograins)

  20. Formation of centimeter Fe-based bulk metallic glasses in low vacuum environment

    Energy Technology Data Exchange (ETDEWEB)

    Pan Jie; Chen Qi; Li Ning [State Key Lab of Materials Processing and Mould Technology, Department of Materials Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Liu Lin [State Key Lab of Materials Processing and Mould Technology, Department of Materials Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)], E-mail: lliu2000@public.wh.hb.cn

    2008-09-08

    The formation of a Fe{sub 43.7}Co{sub 7.3}Cr{sub 14.7}Mo{sub 12.6}C{sub 15.5}B{sub 4.3}Y{sub 1.9} bulk metallic glass (BMG) was attempted in low vacuum environment and in air using commercial raw materials. The glass forming ability of the Fe-based alloys was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and differential thermal analyzer (DTA). It was found that cylindric rods with diameters ranging from 10 mm to 5 mm could be successfully fabricated by copper-mold casting in the pressures from 1.5 Pa to 10{sup 5} Pa (10{sup 5} Pa = 1 atm). All BMGs exhibit a distinct glass transition and wide supercooled liquid region. The preparation condition seems not significantly affected by the thermodynamic parameters of BMG, such as supercooled liquid region, glass transition temperature and melting process. The oxygen content of the alloys prepared in different vacuum conditions was measured by a LECO oxygen analyzer, which revealed that the oxygen content was less than 100 ppm for all BMGs prepared, even in air. The good glass forming ability and excellent oxidation resistance for the present Fe-based alloy are discussed.

  1. Temperature dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1}

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Hernando, A.; Aragon, A.; Marin, P. [Instituto de Magnetismo Aplicado, IMA, P.O. Box 155, 28230 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer An anomalous thermal dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles under 25 {mu}m powder particle, increasing Hc as temperature increases. Black-Right-Pointing-Pointer It is proposed that Cu rich regions at inter-grain boundaries could act as exchange decoupling regions contributing to the thermal increase of coercivity. Black-Right-Pointing-Pointer This anomalous thermal dependence points out that tailoring microstructure and size, by controlling the cooling rate of more adequate multiphase systems, could be a promising procedure to develop soft or hard magnets, avoiding Rare Earths metals that is nowadays an important target for the engineering of magnetic materials. - Abstract: In this work, the dependence of the coercive field of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} gas atomized powder with the temperature for different particle sizes has been studied, observing an anomalous behavior in the under 25 powder particle size fraction. This unusual behavior is related with the microstructure of the powder, and is attributed to the presence of a multiphase magnetic system, with non-magnetic regions decoupling the ferromagnetic domains.

  2. Microstructural characterization of Mg-based bulk metallic glass and nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Babilas, Rafał, E-mail: rafal.babilas@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego 18a St., 44-100 Gliwice (Poland); Nowosielski, Ryszard; Pawlyta, Mirosława [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego 18a St., 44-100 Gliwice (Poland); Fitch, Andy [European Synchrotron Radiation Facility, CS40220, 38043 Grenoble (France); Burian, Andrzej [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice (Poland)

    2015-04-15

    New magnesium-based bulk metallic glasses Mg{sub 60}Cu{sub 30}Y{sub 10} have been prepared by pressure casting. Glassy alloys were successfully annealed to become nanocomposite containing 200 nm crystallites in an amorphous matrix. The microstructure of bulk glassy alloy and nanocomposite obtained during heat treatment was examined by X-ray diffraction and scanning and high-resolution electron microscopy. Metallic glass has been also studied to explain the structural characteristics by the reverse Monte Carlo (RMC) modeling based on the diffraction data. The HRTEM images allow to indicate some medium-range order (MRO) regions about 2–3 nm in size and formation of local atomic clusters. The RMC modeling results confirmed some kinds of short range order (SRO) structures. It was found that the structure of bulk metallic glass formed by the pressure casting is homogeneous. The composite material contained very small particles in the amorphous matrix. Homogeneous glassy alloy had better corrosion resistance than a composite containing nanocrystalline particles in a glassy matrix. - Highlights: • RMC modeling demonstrates some kinds of SRO structures in Mg-based BMGs. • HRTEM indicated MRO regions about 2–3 nm and SRO regions about 0.5 nm in size. • Mg-based glassy alloys were successfully annealed to become nanocomposite material. • Crystalline particles have spherical morphology with an average diameter of 200 nm. • Glassy alloy had higher corrosion resistance than a nanocomposite sample.

  3. Composites of amorphous and nanocrystalline Zr–Cu–Al–Nb bulk materials synthesized by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, P., E-mail: philipp.drescher@uni-rostock.de [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Witte, K. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Yang, B. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Steuer, R.; Kessler, O. [Chair of Materials Science, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Burkel, E. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Schick, C. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Seitz, H. [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany)

    2016-05-15

    The fabrication of Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} bulk metallic glass composite samples by spark plasma sintering (SPS) process has been successfully realized. The unique characteristics of bulk metallic glasses could lead to the possibility of future applications as new structural and functional materials. The densification of an amorphous Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} powder was realized in a systematic study changing the sintering temperature in the SPS process leading to stable composites characteristic of amorphous and nanocrystalline structures. X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) analysis, transmission electron microscopy (TEM) as well as hardness tests were applied to determine the structural and mechanical properties of the sintered materials. A stable amorphous bulk metallic glass based on Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} with a low fraction of crystallites could be fabricated applying a nominal sintering temperature of 400 °C. Higher sintering temperatures lead to composites with high fractions of nanocrystalline material with porosities below 0.5%.

  4. Glassy behavior of the Nd sublattice induced by Fe doping in NdFexGa1-xO3

    International Nuclear Information System (INIS)

    Bartolome, F.; Parra-Borderias, M.; Blasco, J.; Bartolome, J.

    2007-01-01

    The evolution of the magnetic ordering of Nd with the Fe content in NdFe x Ga 1-x O 3 is studied by low-temperature specific-heat measurements for x= =0.2. Fe doping creates a distribution of internal fields on Nd, originating a Schottky contribution to the specific heat which is present for x>0. The power law followed by the low-temperature specific heat suggests a glassy behavior for x>=0.1

  5. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y-(HF) n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator.

    Science.gov (United States)

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y - produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y - (HF) n (Y=F, O 2 ), where larger clusters with n ≥4 were not detected. The mechanisms for the formation of the HF, F - (HF) n , and O 2 - (HF) n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F - (HF) n ( n =1-3), the energies for the loss of HF from F - (HF) 3 , F - (HF) 2 , and F - (HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy ( E CM ). These E CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O 2 (HF) n ] - ( n =1-4) was discussed on the basis of the bond lengths of O 2 H-F - (HF) n and O 2 - H-F(HF) n obtained by ab initio calculations. The calculations indicated that [O 2 (HF) 4 ] - separated into O 2 H and F - (HF) 3 .

  6. Effect of alloying Mo on mechanical strength and corrosion resistance of Zr-1% Sn-1% Nb-1% Fe alloy

    International Nuclear Information System (INIS)

    Sugondo

    2011-01-01

    It had been done research on Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy. The ingot was prepared by means of electrical electrode technique. The chemical analysis was identified by XRF, the metallography examination was perform by an optical microscope, the hardness test was done by Vickers microhardness, and the corrosion test was done in autoclave. The objective of this research were making Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy with Mo concentration; comparing effect of Mo concentration to metal characteristics of Zr-1%Sn-1%Nb-1%Fe which covered microstructure; composition homogeneity, mechanical strength; and corrosion resistance in steam, and determining the optimal Mo concentration in Zr-1%Sn-1%Nb-1%Fe-(x)% Mo alloy for nuclear fuel cladding which had corrosion resistance and high hardness. The results were as follow: The alloying Mo refined grains at concentration in between 0,1%-0,3% and the concentration more than that could coarsened grains. The hardness of the Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was controlled either by the flaw or the dislocation, the intersection of the harder alloying element, the solid solution of the alloying element and the second phase formation of ZrMo 2 . The corrosion rate of the Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was controlled by the second phase of ZrMo 2 . The 0.3% Mo concentration in Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was the best for second phase formation. The Mo concentration in between 0,3-0,5% in Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was good for the second phase formation and the solid solution. (author)

  7. Phase diagrams for pseudo-binary carbide systems TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC and HfC-TaC

    International Nuclear Information System (INIS)

    Gusev, A.I.

    1985-01-01

    Parameters of interaction and energy of mutual exchange in the liquid and solid phases of pseudobinary TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC, HfC-TaC systems are calculated with account of dependence on composition and temperature. Positions of liquidus-solidus phase boundaries on the phase diagrams of the mentioned systems are calculated on the basis of the determined mutual exchange energies in approximati.on of subregular solutions. The existance of latent decomposition ranges in the solid phase on the phase diagrams of the investgated systems is established

  8. Magnetisation reversal on surface of Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Sun, H.; Woodward, R.; Street, R.

    1998-01-01

    Full text: Time dependent magnetisation processes on surface of isotropic and anisotropic Nd-Fe-B magnets were measured using a Magneto-Optic Magnetometer (MOM) and the data were analysed by means of the constitutive equation H = H(M, M). The surface magnetic viscosity parameter Λ (or fluctuation field H f ) was obtained. The activation volume v, which represents the volume of a negative magnetisation nuclei during a magnetisation reversal process was calculated from Λ. The results are compared with those of the corresponding bulk properties obtained by analysing the data measured using a Vibrating Sample Magnetometer (VSM). Similar to bulk materials, Λ for the surface magnetisation is nearly constant over a wide range of magnetisation for both isotropic and anisotropic Nd-Fe-B. However, the surface hysteresis loops are significantly different from the bulk materials, indicating a significant difference in the magnetisation reversal processes between the bulk and surface materials. The surface magnetisation reversal mechanism, its relation and influence to the bulk properties and therefore the performance of permanent magnet are discussed

  9. 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

  10. Structural and magnetic properties of Fe76P5(Si0.3B0.5C0.2)19 amorphous alloy

    International Nuclear Information System (INIS)

    Lavorato, G.C.; Fiore, G.; Tiberto, P.; Baricco, M.; Sirkin, H.; Moya, J.A.

    2012-01-01

    Highlights: ► Fe 76 P 5 (Si 0.3 B 0.5 C 0.2 ) 19 amorphous alloy in ribbons and 1 mm and 2 mm rod samples. ► Good glass forming ability with ΔT = 50 K and γ = 0.37 and off-eutectic composition. ► Good soft magnetic properties with magnetization saturation of 1.44 T. ► Geometrical factors are the primary causes of magnetic losses in frequencies above 10 Hz. - Abstract: Recently, bulk amorphous alloys were produced in the Fe–B–Si–P–C system with high glass forming ability, excellent magnetic properties and the advantage of containing no expensive glass-forming elements, such as Ga, Y, Cr or Nb, having, therefore, a good perspective of commercial applications. In the present work, the Fe 76 P 5 (Si 0.3 B 0.5 C 0.2 ) 19 amorphous alloy prepared by two quenching techniques has been studied. Amorphous ribbons of about 40 μm thick were obtained by planar-flow casting together with cylinders having 1 and 2 mm diameter produced by copper mold injection casting. All the samples appear fully amorphous after X-ray diffraction analysis. A comprehensive set of thermal data (glass, crystallization, melting and liquidus temperatures) were obtained as well as a description of the melting and solidification processes. Mechanical microhardness tests showed that the samples have a hardness of 9.7 ± 0.3 GPa. Good soft-magnetic properties were obtained, including a high magnetization of 1.44 T and a low coercivity (4.5 A/m for ribbons and 7.5 A/m in the case of 1 mm rod samples, both in as-cast state). Thermomagnetic studies showed a Curie temperature around 665 K and the precipitation of new magnetic phases upon temperatures of 1000 K. Furthermore, the frequency dependence of magnetic losses at a fixed peak induction was studied. The results suggest the occurrence of a fine magnetic domain structure in bulk samples. The good soft magnetic properties of the bulk metallic glass obtained by copper mold casting for this particular Fe-based composition suggests possible

  11. Combined ion beam and hyperfine interaction studies of LiNbO3 single crystals

    International Nuclear Information System (INIS)

    Marques, J.G.; Kling, A.; Soares, J.C.; Rebouta, L.

    1999-01-01

    A review of recent studies of LiNbO 3 crystals doped with Hf and Mg,Hf combining high precision RBS/channelling, PIXE/channelling and hyperfine interaction techniques is presented. The lattice location of Hf was found to depend strongly on the dopant concentration, crystal stoichiometry and Mg co-doping level. At low concentrations Hf occupies Li sites in congruent crystals, while it occupies both Li and Nb sites for higher doping levels or in near-stoichiometric crystals. Co-doping with Mg also forces a split location of Hf in Li and Nb sites and when the MgO amount exceeds 4.5 mol% Hf occupies only Nb sites. Neutron irradiation of these crystals displaces Hf from its initial lattice site and leads to a strong decrease of the Nb site fraction. The results are discussed in the framework of the Li and Nb vacancy models currently proposed in the literature for the defect structure of LiNbO 3 . (author)

  12. Enhanced saturation magnetization of Fe{sub 3}Si nanodot-embedded Fe{sub 80}Si{sub 17}Nb{sub 3} flexible film for efficient wireless power transfer

    Energy Technology Data Exchange (ETDEWEB)

    Pai, Yi-Hao, E-mail: paiyihao@mail.ndhu.edu.tw; Yan, Zih-Yu; Fu, Ping-Hao

    2013-07-15

    An efficient magnetically coupled resonance response is performed using an iron silicide-based nanostructured magnetoelectric material with high saturation magnetization for the wireless charging of battery-powered consumer electronics. With 500 °C annealing, the self-assembled Fe{sub 3}Si nanodots buried in the Fe{sub 80}Si{sub 17}Nb{sub 3} host matrix with (220) lattice spacing of 1.99 Å corresponding to a volume density of 8.96 × 10{sup 16} cm{sup 3}, can be obtained and a maximum saturation magnetization of 244 emu g{sup −1} achieved. The return loss of the antenna will be tuned to match the designed frequency with greater attenuated intensity (−0.39 dB) and a relatively narrow bandwidth (6 kHz) when the Fe{sub 3}Si nanodot-embedded Fe{sub 80}Si{sub 17}Nb{sub 3} sample is placed in a WiTricity system. An efficient wireless power transfer can be created and improved from 47.5% to 97.3%. The associated coil and loop antenna resonators are significantly readjusted to match the power transfer by putting this nanostructured magnetoelectric material in a WiTricity system. - Highlights: • The saturation magnetization is effective enhancement in the presence of Fe{sub 3}Si nanodot buried in the Fe{sub 80}Si{sub 17}Nb{sub 3}. • A saturation magnetization of 244 emu g{sup −1} is proposed for high-efficiency wireless power transfer. • The return loss of the antenna will be tuned to match the designed frequency. • Such a wireless power transfer can be enhanced efficiency up to 97.3%.

  13. Study on soft magnetic properties of Finemet-type nanocrystalline alloys with Mo substituting for Nb

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Dehui; Zhou, Bingwen; Jiang, Boyu; Ya, Bin; Zhang, Xingguo [School of Materials Science and Engineering, Dalian University of Technology, Dalian (China)

    2017-10-15

    The thermal stability, microstructure, and soft magnetic properties as a function of annealing time were studied for Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 3-x}Mo{sub x} (x = 0, 1, 2, 3) (atom percent, at.%,) ribbons. It was found that substituting Nb by Mo reduced the thermal stability. After 15 min short time vacuum annealing, Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 2}Mo{sub 1} and Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 1}Mo{sub 2} samples obtained higher permeability and similar coercivity compared to the original Finemet alloy (Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 3}), Mo substituting Nb reduced the optimum annealing time in Finemet-type alloys, and meanwhile marginally increased the saturation magnetization. Substituting all Nb by Mo led to the earlier formation of non-soft magnetic phase, thus deteriorated the soft magnetic properties. XRD and TEM structural analysis showed that in Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 2}Mo{sub 1} and Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 1}Mo{sub 2} samples (annealed for 15 min), nanocrystals ∝10 nm in size were obtained, and the good soft magnetic properties of these alloys could be attributed to the small grain size. The relationship between annealing time, soft magnetic properties, and microstructure was established. Reducing annealing time and temperature to obtain best soft magnetic properties could cut down the production costs of Finemet-type alloys. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Electronic-structure origin of the glass-forming ability and magnetic properties in Fe–RE–B–Nb bulk metallic glasses

    International Nuclear Information System (INIS)

    Li, J.W.; Estévez, D.; Jiang, K.M.; Yang, W.M.; Man, Q.K.; Chang, C.T.; Wang, X.M.

    2014-01-01

    Highlights: • Relation between GFA and electronic structure of RE doped BMGs is investigated. • Tm enhances RE–B bonds and decreases the density of states near the Fermi level. • Magnetic properties of the alloys are related to the electronic structure of RE. - Abstract: (Fe 0.71 RE 0.05 B 0.24 ) 96 Nb 4 (RE = Gd, Tb, Ho, Er, Tm) bulk metallic glasses (BMGs) were found exhibiting excellent glass-forming ability (GFA) with critical diameters ranging from 3.5 to 6.5 mm, and high compressive fracture strength larger than 4300 MPa. Moreover, they displayed good soft-magnetic properties with saturation magnetic flux density of 0.71–0.87 T, coercive force of 1.23–39.76 A/m and effective permeability of 1500–12,740 at 1 kHz. X-ray photoelectron spectroscopy was performed to clarify the origin of the excellent GFA from the viewpoint of electronic structure. It was found that the Tm doped alloy displayed unique electronic structure including the deepest core-level binding energy, the most numerous RE–B bonds and the minimum density of states near the Fermi level, making this alloy the best glass former. The various trends noticed in the magnetic properties were ascribed mainly to the differences in the magnetic anisotropy and magnetic moment of RE elements

  15. Quantum Well States in Fe/Nb(001) Multilayers: First Principles Study

    National Research Council Canada - National Science Library

    Sliukia, Nitya N; Sen, A; Prasad, R

    2007-01-01

    A first principle study to understand the phenomena of interlayer exchange coupling in Fe/Nb multilayers using the linearized-muffin-tin-orbitals method within the generalized gradient approximation was performed...

  16. Thermal and electric conductivity of Cu50Zr35Ti8Hf5Nb2 volume amorphous alloy

    International Nuclear Information System (INIS)

    Gavrenko, O.A.; Merisov, B.A.; Mikhajlova, T.N.; Molokanov, V.V.; Sologubenko, A.V.; Khadzhaj, G.Ya.

    1996-01-01

    The temperature dependences of thermal conductivity and electric resistance of the Cu 50 Zr 35 Ti 8 Hf 5 Nb 2 volume amorphous alloy experimentally studied within the temperature range of 1.8-240 K. The temperature dependence of electrical resistance is well described by the ratio, taking into account the electron scattering on the phonons and in the two-level systems

  17. Hydrogen absorption in epitaxial W/Nb(001) and polycrystalline Fe/Nb(110) multilayers studied in-situ by X-ray/neutron scattering techniques and X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Klose, F.; Rehm, C.; Fieber-Erdmann, M.; Holub-Krappe, E.; Bleif, H. J.; Sowers, H.; Goyette, R.; Troger, L.; Maletta, H.

    1999-01-01

    Hydrogen can be absorbed in large quantities by 100 A thin Nb layers embedded in epitaxial W/Nb and polycrystalline Fe/Nb multilayers. The solubility and the hydrogen-induced structural changes of the host lattice are explored in-situ by small-angle neutron/X-ray reflectometry and high-angle diffraction. These measurements reveal for both systems that the relative out-of-plane expansion of the Nb layers is considerably larger than the relative increase of the Nb interplanar spacing indicating two distinctly different mechanisms of hydrogen absorption. In Fe/Nb multilayers, hydrogen expands the Nb interplanar spacing in a continuous way as function of the external pressure. In contrast, the Nb lattice expansion is discontinuous in epitaxial W/Nb multilayers: A jump in the Nb(002) Bragg reflection position occurs at a critical hydrogen pressure of 1 mbar. In-situ EXAFS spectroscopy also exhibits an irreversible expansion of the Nb lattice in the film plane for p H2 > 1 mbar. This can be regarded as a structural phase transition from an exclusively out-of-plane to a three-dimensionally expanded state at low and high hydrogen pressures, respectively

  18. EIS study of the redox reaction of Fe(CN)63-/4- at glassy carbon electrode via diazonium reduction in aqueous and acetonitrile solutions

    Energy Technology Data Exchange (ETDEWEB)

    Khoshroo, M.; Rostami, A. [Mazandaran Univ., Babolsar (Iran, Islamic Republic of). Dept. of Physical Chemistry

    2008-07-01

    This paper reported on a study that characterized soluble electroactive species by cyclic voltammetry to investigate the presence of grafted films and their blocking properties. In particular, the authority of the glassy carbon electrode modification conditions on the cyclic voltammetric response of Fe(CN)63-/4- oxido-reduction was examined for 2 layers grafted by electrochemical reduction of diazonium salts in acetonitrile and aqueous solutions. PAA and Fast Black K modified glassy carbon electrodes exhibited a significant blocking behaviour for oxidation and reduction reactions of the Fe(CN)63-/4- redox system in aqueous and acetonitrile solutions. The study showed that the blocking effect increased which changes in time and concentration of diazonium salts in acetonitrile solution. Electrochemical impedance spectroscopy (EIS) measurements showed that the physical barrier of grafted layers prevent the access of Fe(CN)63-/4- to the underlying glassy carbon electrode. Therefore the RCT resistance increases during the modification treatment. The substituted phenyl layers are much more compact and less permeable in a nonaqueous solvent than with an aqueous solvent. Electrochemical impedance measurements indicate that the kinetics of electron transfer slow down when the time and the concentration used to modify the glassy carbon electrode increase. 4 refs., 1 fig.

  19. Magnetovolume effects and magnetic transitions in the invar systems Fe65Ni35 and Er2Fe14B at high hydrostatic pressure

    International Nuclear Information System (INIS)

    Sidorov, V.A.; Khvostantsev, L.G.

    1994-01-01

    The relative volume change and the initial ac-susceptibility have been measured for Fe 65 Ni 35 and Er 2 Fe 14 B under hydrostatic pressure up to 8.5 GPa at room temperature. The bulk modulus of Fe 65 Ni 35 begins to rise and the susceptibility begins to drop at 3.5-4 GPa, indicating the continuous disappearance of ferromagnetism at high pressure. The transition from ferromagnetic to paramagnetic state in Er 2 Fe 14 B at 5.7 GPa is more abrupt and the giant (order of magnitude) softening of the bulk modulus is observed before this transition. The spin reorientation (SR) transition in Er 2 Fe 14 B shifts under pressure to lower temperatures (dT SR /dP = -19 K/GPa). (orig.)

  20. Reactive diffusion in amorphous Fe-B and Co-Zr multilayer films

    International Nuclear Information System (INIS)

    Stobiecki, F.

    1989-01-01

    The diffusion in Fe 1-x B x /Fe 1-y B y and Co 1-x Zr x /Co 1-y Zr y amorphous bi- and multilayers was investigated. The dependence of the diffusion coefficient on concentration was observed. This effect is explained taking into account the concentration dependence of mixing enthalpy correlated with chemical short range order in the amorphous state

  1. Amorphous Fe-B alloys in B-Fe-Ag multilayers studied by magnetization and Mössbauer measurements

    DEFF Research Database (Denmark)

    Kiss, L. F.; Balogh, J.; Bujdoso, L.

    2011-01-01

    Bulk and local magnetic properties were studied in [1 nm B + 1 nm 57Fe + x nm Ag]5, x = 1, 2, 4, 5 and 10, multilayer samples. Although Ag does not mix with either of the other two elements the magnetic properties of the multilayers are strongly influenced by the Ag thickness below x = 5, whereas...

  2. Moessbauer spectroscopy on amorphous Fe/sub x/Ni/sub 80-x/B/sub 20/ after neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, J.; Miglierini, M. (Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia))

    1985-05-16

    Amorphous Fe/sub x/Ni/sub 80-x/B/sub 20/ glassy alloys (x = 40, 50, 60, and 70) irradiated with fast neutrons in a fluence range of 10/sup 14/ to 10/sup 19/ cm/sup -2/ were investigated by Moessbauer spectroscopy. There were some significant changes in the Moessbauer spectrum parameters of the 10/sup 19/ cm/sup -2/ irradiated samples except Fe/sub 40/Ni/sub 40/B/sub 20/. This corresponds to a change in the direction of the easy axis of magnetization. The measurements show that the resistance of the Fe-Ni-B system against neutron irradiation improves with increasing Ni content up to a certain point.

  3. Characterization of lithium niobate monocrystals doped with iron (Li Nb O3:Fe)

    International Nuclear Information System (INIS)

    Mastelaro, V.R.; Terrile, N.C.; Nascimento, O.R.; Nicolo, I.

    1988-01-01

    LiNbO 3 :Fe Crystals were analised using EPR Optical absorption spectroscopy and holographic techniques. The site occupied by Fe 3+ is discused and the effect of thermal treatments on Fe 2+ and OH - concentration is studied. The high diffraction efficiency, measure by holographic techniques shows that crystals are particularly good for holographic applications. (author) [pt

  4. Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

    Science.gov (United States)

    Li, Shanghua; Qin, Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

    2009-05-01

    PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

  5. Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

    International Nuclear Information System (INIS)

    Li Shanghua; Qin Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

    2009-01-01

    PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

  6. In situ visualization of Ni-Nb bulk metallic glasses phase transition

    OpenAIRE

    Oreshkin, A. I.; Mantsevich, V. N.; Savinov, S. V.; Oreshkin, S. I.; Panov, V. I.; Yavari, A. R.; Miracle, D. B.; Louzguine-Luzgin, D. V.

    2013-01-01

    We report the results of the Ni-based bulk metallic glass structural evolution and crystallization behavior in situ investigation. The X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-beam diffraction (NBD), differential scanning calorimetry (DSC), radial distribution function (RDF) and scanning probe microscopy/spectroscopy (STM/STS) techniques were applied to analyze the structure and electronic properties of Ni63.5Nb36.5 glasses before and after crystallization. It was...

  7. Laachite, (Ca,Mn){sub 2}Zr{sub 2}Nb{sub 2}TiFeO{sub 14}, a new zirconolite-related mineral from the Eifel volcanic region, Germany

    Energy Technology Data Exchange (ETDEWEB)

    Chukanov, Nikita V. [Institute of Problems of Chemical Physics, Chernogolovka (Russian Federation); Krivovichev, Sergey V.; Pakhomova, Anna S. [St. Petersburg State Univ. (Russian Federation). Faculty of Crystallography; Pekov, Igor V.; Vigasina, Marina F. [Moscow State Univ. (Russian Federation). Faculty of Geology; Schaefer, Christof [Suedwestdeutsche Salzwerke AG, Heilbronn (Germany); Van, Konstantin V. [Russian Academy of Sciences, Chernogolovka (Russian Federation). Inst. of Experimental Mineralogy

    2014-02-15

    The new mineral laachite was discovered in a sanidinite specimen from the Laach Lake (Laacher See) volcano, Eifel region, Rheinland-Pfalz, Germany. Associated minerals are sanidine, allanite-(Ce), baddeleyite, hau¨yne, hedenbergite, intermediate members of the jacobsite-magnetite series, phlogopite, rhodonite, spessartine, tephroite, thorite, zircon, and a pyrochlore-group mineral. Laachite is deep brownish-red, has an adamantine lustre, and is translucent; the streak is brownish red. It forms longprismatic crystals up to 0.02 x 0.04 x 0.5 mm, which are present as random intergrowths and twins in cavities within sanidinite. The density calculated from the empirical formula is 5.417 g/cm{sup 3}. The mean refractive index calculated from the Gladstone-Dale relationship is 2.26. The Raman spectrum shows the absence of hydrogen-bearing groups. The chemical composition is (electron microprobe, mean of 5 analyses, wt. %): CaO 4.29, MnO 9.42, FeO 5.73, Y{sub 2}O{sub 3} 2.56, La{sub 2}O{sub 3} 2.00, Ce{sub 2}O{sub 3} 6.37, Nd{sub 2}O{sub 3} 2.22, Al{sub 2}O{sub 3} 0.99, ThO{sub 2} 7.75, TiO{sub 2} 10.98, ZrO{sub 2} 19.39, Nb{sub 2}O{sub 5} 27.82, total 99.52. The empirical formula based on 14 O atoms is: (Ca{sub 0.66}Mn{sub 0.37}Th{sub 0.25}Y{sub 0.20}La{sub 0.11}Ce{sub 0.34}Nd{sub 0.11})(Zr{sub 1.3} {sub 6}Mn{sub 0.64})(Nb{sub 1.81}Ti{sub 1.19})(Fe{sub 0.69}Al{sub 0.17}Mn{sub 0.14})O{sub 14.00}. The simplified formula, taking into account the structural data, is: (Ca,Mn){sub 2}(Zr,Mn){sub 2}Nb{sub 2}TiFeO{sub 14}. Laachite is monoclinic, space group C2/c, a = 7.3119(5), b = 14.1790(10), c = 10.1700(7)Aa, β = 90.072(2), V = 1054.38(1) Aa{sup 3}, Z = 4. The crystal structure was solved using single-crystal X-ray diffraction data. Laachite is a monoclinic analogue of zirconolite-3O, CaZrTi{sub 2}O{sub 7}, with Nb dominant over Ti in the octahedral sites Nb1 and Nb2 and Fe dominant in a site with four-fold coordination. The strongest lines of the powder X-ray diffraction

  8. Surface characterization of amorphous and crystallized Fe 80B 20

    Science.gov (United States)

    Huntley, D. R.; Overbury, S. H.; Zehner, D. M.; Budai, J. D.; Brower, W. E.

    1986-11-01

    Recent studies of catalysis by amorphous metals have prompted an interest in their surface properties. We have utilized Auger electron spectroscopy, X-ray photoelectron spectroscopy and low energy alkali ion scattering to study the surface composition, electronic properties and topography of amorphous and crystallized Fe 80B 20 ribbons. The majorresults are that the surface stoichiometry is approximately that of the bulk, unaltered by segregation. Bulk crystallization results in the diffusion of impurities to the surface, but does not change the Fe/B ratio. A small shift in the B1s core level binding energy was observed on crystalline, annealed surfaces relative to amorphous or sputtered surfaces, but no shifts were observed in the iron core level energies. A weak feature due to the B2p levels was observed in the valence band spectra from sputtered surfaces. The surfaces exhibit atomic scale roughness which is not altered by bulk crystallization. Finally, there were no observable differences in the structure, composition or electronic properties between the two sides of the ribbons.

  9. Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

    Science.gov (United States)

    Apparao, K. Ch; Birru, Anil Kumar

    2018-01-01

    A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

  10. Glassy selenium at high pressure: Le Chatelier's principle still works

    Science.gov (United States)

    Brazhkin, V. V.; Tsiok, O. B.

    2017-10-01

    Selenium is the only easily vitrified elementary substance. Numerous experimental studies of glassy Se (g -Se) at high pressures show a large spread in the data on the compressibility and electrical resistivity of g -Se. Furthermore, H. Liu et al. [Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] have arrived at the surprising conclusion that the volume of glass increases during pressure-induced crystallization. We have performed high-precision measurements of the specific volume and electrical resistivity of glassy selenium (g -Se) at high hydrostatic pressures up to 9 GPa. The measured bulk modulus at normal pressure is B =(9.0 5 ±0.15 ) GPa and its pressure derivative is BP'=6.4 ±0.2 . In the pressure range P <3 GPa, glassy selenium has an anomalously large negative second derivative of the bulk modulus. The electrical resistivity of g -Se decreases almost exponentially with increasing pressure and reaches 20 Ω cm at a pressure of 8.75 GPa. The inelastic behavior and weak relaxation of the volume for g -Se begin at pressures above 3.5 GPa; the volume and logarithm of the electrical resistivity relax significantly (logarithmically with the time) at pressures above 8 GPa. Bulk measurements certainly indicate that the volume of g -Se glass in the crystallization pressure range is larger than the volumes of both appearing crystalline phases (by 2% and 4%). Therefore, the "volume expansion phenomenon" suggested in [H. Liu et al., Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] is not observed, and the pressure-induced crystallization of glassy selenium is consistent with the laws of thermodynamics.

  11. Microstructural evolution and structure property correlation in Zr-1Nb and Zr-1Nb-1Sn-0.1Fe alloys

    International Nuclear Information System (INIS)

    Neogy, S.; Srivastava, D.; Chakravartty, J.K.; Dey, G.K.

    2005-01-01

    This study summarizes the evolution of microstructure and precipitation behavior in binary Zr-1Nb and quaternary Zr-1Nb-1Sn-0.1Fe alloys after different thermo mechanical processing. The processed microstructure and morphology of constituent phases and precipitates have been studied in detail using transmission electron microscopy (TEM). Microstructural studies have revealed the shape, size, size distribution and the nature of precipitate phases. Martensite formation and its tempering behavior have been studied in detail in both the alloys. Recrystallization studies on these alloys have been carried out with a view to understand the recrystallization mechanism. In case of the binary alloy the second phase recipitates were of the β type having composition varying from β I (20 wt% Nb) to β II (85 wt% Nb) depending on the heat treatment temperature and time. The second phase precipitates in the quaternary alloy were intermetallic Zr-Nb-Fe type and also β type rich in Zr. The orientation relationship existing between the precipitating phases and the a matrix were established in case of both the alloys. High resolution electron microscopy (HREM) of the martensitic microstructure and the recrystallized microstructure has revealed the internal structure and the interface structure of the martensite and the precipitating phases respectively. Structure-property correlation studies have been carried out on the heat-treated samples to evaluate the effect of the thermo mechanical processing on the microstructures and hence mechanical properties. (author)

  12. 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.

  13. Phase stability predictions of Cr1−x, Mx)2(Al1−y, Ay)(C1−z, Xz) (M = Ti, Hf, Zr; A = Si, X = B)

    International Nuclear Information System (INIS)

    Shang, Lin; Music, Denis; Baben, Moritz to; Schneider, Jochen M

    2014-01-01

    The phase stability of (Cr 1−x , M x ) 2 (Al 1−y , A y )(C 1−z , X z ) (M = Ti, Hf, Zr; A = Si, X = B, space group P6 3 /mmc, prototype Cr 2 AlC) was studied using ab initio calculations. Based on the energy of mixing data as well as the density of states (DOS) analysis, (Cr 1−x , Zr x ) 2 AlC and (Cr 1−x , Hf x ) 2 AlC are predicted to be unstable, whereas (Cr 1−x , Ti x ) 2 AlC, Cr 2 (Al 1−y , Si y )C and Cr 2 Al(C 1−z , B z ) are predicted to be stable or metastable. The density of states analysis reveals that small differences in the position of the Fermi level alters the phase stability: (Cr 1−x , Zr x ) 2 AlC and (Cr 1−x , Hf x ) 2 AlC are predicted to be unstable or metastable as the Fermi level lies at a peak position. While the Cr dominated DOS for (Cr 1−x , Ti x ) 2 AlC plateaus at the Fermi level indicating stability. Implications of these results for the vapour phase condensation of self-healing Cr 2 AlC based materials are discussed. (paper)

  14. Mecano-synthesis of the alloy 25%Fe-50%Cu-25%Nb; Mecano-sintese da liga 25%Fe-50%Cu-25%Nb

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Keytiane; Oliveira, Michel Picanco de; Guimaraes, Renan da Silva; Moreira Junior, Valdenir; Filgueira, Marcello, E-mail: marcello.filgueira@pq.cnpq.br [Universidade Estadual do Norte Fluminense (CCT/LAMAV/UENF), Campos dos Goytacazes, RJ (Brazil)

    2016-07-01

    In general, this study aims at the application of mechanical grinding to the system 25% Fe-50% Cu-25% Nb and studies the production process of these powders during milling. The evolution of the structure during the synthesis and the effect of variation of the grinding time were studied by diffraction of X-rays (XRD) and Scanning Electron Microscopy coupled EDS (SEM + EDS) in order to obtain the sizes of crystallites, the phase formation and its evolution with grinding time, and also the homogeneity of the mixture. The particle size distribution was analyzed by laser sedigraph technique. The powders synthesis were performed for milling time of 2.5, 5 and 10 hours. The mechanical grinding showed to be effective with the solid solution formation in the early grinding times. The XRD showed the solid solution formation with subsequent reduction and disappearance of Cu peaks. Through the technique of laser sedigraph it was observed the increase of the particle size followed by the its reduction in the milling time of 10h, a fact that characterizes the mechanical grinding process for ductile powder particles. Thus, the study demonstrated the effectiveness of the mechanical grinding to obtain powder of Fe-Cu-Nb and further processing and application of diamond cutting tools. (author)

  15. Hyperfine interaction and some thermomagnetic properties of amorphous and partially crystallized Fe70−xMxMo5Cr4Nb6B15 (M = Co or Ni, x = 0 or 10 alloys

    Directory of Open Access Journals (Sweden)

    Rzącki Jakub

    2015-03-01

    Full Text Available As revealed by Mössbauer spectroscopy, replacement of 10 at.% of iron in the amorphous Fe70Mo5Cr4Nb6B15 alloy by cobalt or nickel has no effect on the magnetic structure in the vicinity of room temperature, although the Curie point moves from 190 K towards ambient one. In the early stages of crystallization, the paramagnetic crystalline Cr12Fe36Mo10 phase appears before α-Fe or α-FeCo are formed, as is confirmed by X-ray diffractometry and transmission electron microscopy. Creation of the crystalline Cr12Fe36Mo10 phase is accompanied by the amorphous ferromagnetic phase formation at the expense of amorphous paramagnetic one.

  16. Magnetic properties evolution of a high permeability nanocrystalline FeCuNbSiB during thermal ageing

    Science.gov (United States)

    Lekdim, Atef; Morel, Laurent; Raulet, Marie-Ange

    2017-07-01

    It is found to be one of the major issues while designing an aircraft, mass and volume have to be reduced in order to achieve energy efficiency. This leads to a high compactness of the electrical components which enables them to withstand at high temperatures. The magnetic components which are responsible for the electrical energy conversion, therefore exposed to high temperatures in working conditions. Their thermal ageing becomes a serious problem and deserves a particular attention. The FeCuNbSiB nanocrystalline materials have been selected for this ageing study because they are used in power electronic systems very frequently. The objective of the study is based on monitoring the magnetic characteristics under the condition of several continuous thermal ageing (100, 150, 200 and 240 °C). An important, experimental work of magnetic characterization is being done through a specific monitoring protocol and X-ray diffraction (XRD) along with magnetostriction measurements was carried out to support the study of the evolution of the anisotropy energies with aging. The latter is discussed in this paper to explain and give the hypothesis about the aging phenomena. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

  17. Improved magnetoimpedance and mechanical properties on nanocrystallization of amorphous Fe{sub 68.5}Si{sub 18.5}Cu{sub 1}Nb{sub 3}B{sub 9} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Trilochan [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Proof and Experimental Establishment, Balasore 756025 (India); Majumdar, B. [Defence Metallurgical Research Laboratory, Hyderabad 500068 (India); Srinivas, V., E-mail: veeturi@iitm.ac.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Srinivas, M. [Defence Metallurgical Research Laboratory, Hyderabad 500068 (India); Nath, T.K. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Agarwal, G. [Department of Metallurgical Engineering, Banaras Hindu University, Varanasi 221005 (India)

    2013-10-15

    The effect of heat-treatment temperature on evolution of microstructures, mechanical and soft magnetic properties and magnetoimpedance (MI) effect in rapidly solidified Fe{sub 68.5}Si{sub 18.5}Cu{sub 1}Nb{sub 3}B{sub 9} ribbons, has been investigated. The as-quenched ribbons were subjected to heat-treatment at different temperatures between 400 and 600 °C for 1 h under high vacuum. Detailed structural studies on the ribbons heat-treated at and above 525 °C revealed the presence of nanocrystalline Fe{sub 3}Si phases embedded in a residual amorphous matrix. The ribbon heat-treated at 550 °C temperature exhibits maximum ductility, maximum relative permeability of 4.8×10{sup 4}, minimum coercivity of 0.1 Oe, and maximum MI value of 62%. The enhanced MI effect is believed to be related to the magnetic softening of 550 °C heat-treated ribbons. However, the magnetic properties and MI effect deteriorated in the samples heat-treated above 550 °C due to the coarsening of grain sizes. The soft magnetic behavior of the nanocrystalline ribbons are discussed in the light of random anisotropy model, whereas the MI effect is discussed through standard skin effect in electrodynamics. - Highlights: • Microstructure was tuned by controlled crystallization to obtain superior magnetic properties. • Improved MI in the heat-treated ribbons is attributed to the superior electromagnetic properties. • Correlation between MI and magnetic properties of nc-Fe{sub 68.5}Si{sub 18.5}Cu{sub 1}Nb{sub 3}B{sub 9} is established. • All the observed features are consistent with the proposed random anisotropy model.

  18. Structural and magnetic properties of Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lavorato, G.C. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Fiore, G. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Tiberto, P. [INRIM, Electromagnetism Division, Torino (Italy); Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Sirkin, H. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [GIM - IESIING, Universidad Catolica de Salta, INTECIN (UBA-CONICET) (Argentina)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy in ribbons and 1 mm and 2 mm rod samples. Black-Right-Pointing-Pointer Good glass forming ability with {Delta}T = 50 K and {gamma} = 0.37 and off-eutectic composition. Black-Right-Pointing-Pointer Good soft magnetic properties with magnetization saturation of 1.44 T. Black-Right-Pointing-Pointer Geometrical factors are the primary causes of magnetic losses in frequencies above 10 Hz. - Abstract: Recently, bulk amorphous alloys were produced in the Fe-B-Si-P-C system with high glass forming ability, excellent magnetic properties and the advantage of containing no expensive glass-forming elements, such as Ga, Y, Cr or Nb, having, therefore, a good perspective of commercial applications. In the present work, the Fe{sub 76}P{sub 5}(Si{sub 0.3}B{sub 0.5}C{sub 0.2}){sub 19} amorphous alloy prepared by two quenching techniques has been studied. Amorphous ribbons of about 40 {mu}m thick were obtained by planar-flow casting together with cylinders having 1 and 2 mm diameter produced by copper mold injection casting. All the samples appear fully amorphous after X-ray diffraction analysis. A comprehensive set of thermal data (glass, crystallization, melting and liquidus temperatures) were obtained as well as a description of the melting and solidification processes. Mechanical microhardness tests showed that the samples have a hardness of 9.7 {+-} 0.3 GPa. Good soft-magnetic properties were obtained, including a high magnetization of 1.44 T and a low coercivity (4.5 A/m for ribbons and 7.5 A/m in the case of 1 mm rod samples, both in as-cast state). Thermomagnetic studies showed a Curie temperature around 665 K and the precipitation of new magnetic phases upon temperatures of 1000 K. Furthermore, the frequency dependence of magnetic losses at a fixed peak induction was studied. The results suggest the occurrence of a fine magnetic domain structure in bulk

  19. Zirconium hydrides and Fe redistribution in Zr-2.5%Nb alloy under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Idrees, Y.; Yao, Z. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada); Cui, J.; Shek, G.K. [Kinetrics, Mississauga, ON (Canada); Daymond, M.R., E-mail: daymond@queensu.ca [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada)

    2016-11-15

    Zr-2.5%Nb alloy is used to fabricate the pressure tubes of the CANDU reactor. The pressure tube is the primary pressure boundary for coolant in the CANDU design and is susceptible to delayed hydride cracking, reduction in fracture toughness upon hydride precipitation and potentially hydride blister formation. The morphology and nature of hydrides in Zr-2.5%Nb with 100 wppm hydrogen has been investigated using transmission electron microscopy. The effect of hydrides on heavy ion irradiation induced decomposition of the β phase has been reported. STEM-EDX mapping was employed to investigate the distribution of alloying elements. The results show that hydrides are present in the form of stacks of different sizes, with length scales from nano- to micro-meters. Heavy ion irradiation experiments at 250 °C on as-received and hydrided Zr-2.5%Nb alloy, show interesting effects of hydrogen on the irradiation induced redistribution of Fe. It was found that Fe is widely redistributed from the β phase into the α phase in the as-received material, however, the loss of Fe from the β phase and subsequent precipitation is retarded in the hydrided material. This preliminary work will further the current understanding of microstructural evolution of Zr based alloys in the presence of hydrogen. - Graphical abstract: STEM HAADF micrographs at low magnification showing the hydride structure in Zr-2.5Nb alloy.

  20. Detailed modeling of local anisotropy and transverse Ku interplay regarding hysteresis loop in FeCuNbSiB nanocrystalline ribbons

    Science.gov (United States)

    Geoffroy, Olivier; Boust, Nicolas; Chazal, Hervé; Flury, Sébastien; Roudet, James

    2018-04-01

    This article focuses on the modeling of the hysteresis loop featured by Fe-Cu-Nb-Si-B nanocrystalline alloys with transverse induced anisotropy. The magnetization reversal process of a magnetic correlated volume (CV), characterized by the induced anisotropy Ku, and a deviation of the local easy magnetization direction featuring the effect of a local incoherent anisotropy Ki, is analyzed, taking account of magnetostatic interactions. Solving the equations shows that considering a unique typical kind of CV does not enable accounting for both the domain pattern and the coercivity. Actually, the classical majority CVs obeying the random anisotropy model explains well the domain pattern but considering another kind of CVs, minority, mingled with classical ones, featuring a magnitude of Ki comparable to Ku, is necessary to account for coercivity. The model has been successfully compared with experimental data.

  1. Time effects and glassy state behaviour in superconducting Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x}

    Energy Technology Data Exchange (ETDEWEB)

    Altinkok, A.; Yetis, H.; Olutas, M.; Kilic, K. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey); Kilic, A. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)], E-mail: kilic_a@ibu.edu.tr

    2007-10-01

    The quenched disorder in the moving entity is investigated in a polycrystalline bulk sample of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) by slow transport relaxation measurements (V-t curves) on long time scales. The time evolution of sample voltage (V-t curve) are correlated to spatial reorganization of the driving current together with increasing or decreasing of resistive and non-resistive flow channels in a multiple connected network. In addition, it is shown that the voltage decays appearing in V-t curves are characterized by an exponential time dependence which is analogous to the glassy state relaxation.

  2. Determination of Nb and Zr in U-Nb-Zr alloys by ICP-AES

    International Nuclear Information System (INIS)

    Wang Cuiping; Dong Shizhe; Li Lin; He Meiying

    2003-01-01

    The U-Nb-Zr alloy sample is dissolved by HNO 3 , H 2 O 2 and HF, and the contents of Nb and Zr in the sample are determined on the JY-70 II type ICP-AES by using the internal standard synchronous dilution method. The range of determination is 1%-10% and 0.33%-3.33%, respectively for Nb and Zr. The relative standard deviation is better than 3.2% for Nb, and 2.5% for Zr. The method is rapid and convenient for determining Nb and Zr in U-Nb-Zr alloy sample

  3. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  4. Isothermal oxidation behavior of ternary Zr-Nb-Y alloys at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id [Research Center for Nuclear Materials and Radiometry, Jl. Tamansari 71, Bandung 40132 (Indonesia); Soepriyanto, Syoni; Basuki, Eddy Agus [Metallurgy Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Wiryolukito, Slameto [Materials Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24

    The effect of yttrium content on isothermal oxidation behavior of Zr-2,5%Nb-0,5%Y, Zr-2,5%Nb-1%Y Zr-2,5%Nb-1,5%Y alloy at high temperature has been studied. High temperature oxidation carried out at tube furnace in air at 600,700 and 800°C for 1 hour. Optical microscope is used for microstructure characterization of the alloy. Oxidized and un oxidized specimen was characterized by x-ray diffraction. In this study, kinetic oxidation of Zr-2,5%Nb with different Y content at high temperature has also been studied. Characterization by optical microscope showed that microstructure of Zr-Nb-Y alloys relatively unchanged and showed equiaxed microstructure. X-ray diffraction of the alloys depicted that the oxide scale formed during oxidation of zirconium alloys is monoclinic ZrO2 while unoxidised alloy showed two phase α and β phase. SEM-EDS examination shows that depletion of Zr composition took place under the oxide layer. Kinetic rate of oxidation of zirconium alloy showed that increasing oxidation temperature will increase oxidation rate but increasing yttrium content in the alloys will decrease oxidation rate.

  5. Effects of the Nanostructured Fe-V-Nb Modificators on the Microstructure and Mechanical Properties of Si-Mn Steel

    Directory of Open Access Journals (Sweden)

    Tiebao Wang

    2012-01-01

    Full Text Available The nanostructured Fe-V-Nb master alloy was prepared in vacuum rapid quenching furnace and then was added in the steel melts as modificators before casting. Next, the effects of the nanostructured Fe-V-Nb modificators on the microstructure and mechanical properties of the steel were studied. The results show that the grain size of the steel has been effectively refined, which is mainly because the dispersed nanoscale particles can produce more nucleation sites during the solidification of the liquid steel. Tensile properties and fracture morphology reveal that the yield strength and toughness of the steel modified by nanostructured Fe-V-Nb modificators are better than that of the microalloyed steel. TEM analysis shows that vanadium and niobium in the modificators exist in the form of (V, Nb C which effectively increases the nucleation rate and leads to better mechanical properties of the steel.

  6. Soft magnetism, magnetostriction, and microwave properties of FeGaB thin films

    International Nuclear Information System (INIS)

    Lou, J.; Insignares, R. E.; Cai, Z.; Ziemer, K. S.; Liu, M.; Sun, N. X.

    2007-01-01

    A series of (Fe 100-y Ga y ) 1-x B x (x=0-21 and y=9-17) films were deposited; their microstructure, soft magnetism, magnetostrictive behavior, and microwave properties were investigated. The addition of B changes the FeGaB films from polycrystalline to amorphous phase and leads to excellent magnetic softness with coercivity s , self-biased ferromagnetic resonance (FMR) frequency of 1.85 GHz, narrow FMR linewidth (X band) of 16-20 Oe, and a high saturation magnetostriction constant of 70 ppm. The combination of these properties makes the FeGaB films potential candidates for tunable magnetoelectric microwave devices and other rf/microwave magnetic device applications

  7. A superconducting conveyer system using multiple bulk Y-Ba-Cu-O superconductors and permanent magnets

    Science.gov (United States)

    Kinoshita, T.; Koshizuka, N.; Nagashima, K.; Murakami, M.

    Developments of non-contact superconducting devices like superconducting magnetic levitation transfer and superconducting flywheel energy storage system have been performed based on the interactions between bulk Y-Ba-Cu-O superconductors and permanent magnets, in that the superconductors can stably be levitated without any active control. The performances of noncontact superconducting devices are dependent on the interaction forces like attractive forces and stiffness. In the present study, we constructed a non-contact conveyer for which the guide rails were prepared by attaching many Fe-Nd-B magnets onto an iron base plate. Along the translational direction, all the magnets were arranged as to face the same pole, and furthermore their inter-distance was made as small as possible. The guide rail has three magnet rows, for which the magnets were glued on the iron plate such that adjacent magnet rows have opposite poles like NSN. At the center row, the magnetic field at zero gap reached 0.61T, while the field strengths of two rows on the side edges were only 0.48T due to magnetic interactions among permanent magnets. We then prepared a cryogenic box made with FRP that can store several bulk Y-Ba-Cu-O superconductors 25 mm in diameter cooled by liquid nitrogen. It was found that the levitation forces and stiffness increased with increasing the number of bulk superconductors installed in the box, although the levitation force per unit bulk were almost the same. We also confirmed that these forces are dependent on the configuration of bulk superconductors.

  8. Mineralized lateritic profile in Sn, Zr, Th, Nb, Y and ETR (Serra do Madeira - Pitinga - AM): mineralogical characteristics and geochemical evolution

    International Nuclear Information System (INIS)

    Horbe, Adriana M.C.; Costa, Marcondes L. da

    1997-01-01

    The Pitinga region is located in the north 250 km far from Manaus, in the Amazonas State, Brazil. The Serra do Madeira is the local name of one hill located in the Madeira granite with important primary and supergenic mineralizations of Sn (cassiterite), Zr (zircon), Th (thorite), Nb (columbite and pyroclore), Y and REE (xenotime). The Serra do Madeira was constituted by a lateritic profile with 20 m of thickness where were identified seven horizons: parent rock, saprolite, clayey, bauxitic, concretionary, coluvion and latosol. The lateritization promoted the chemistry instability of the parent-rock forming a clayey material where Al 2 O 3 , Fe 2 O 3 , Sn, Th and Nb were enriched as kaolinite, gibbsite, hematite, goethite, cassiterite, zircon, thorite and columbite; SiO 2 , FeO, CaO, Na 2 O, K 2 O, F, Pb, Rb, and U were leached as quartz, K-feldspar, plagioclase, riebeckite/arfvedsonite, biotite, and iron sulfides; Y, P and ETR were enriched and leached correlated to xenotime, bastnaesite, fluorcerite and probably churchite and ytriofluorite

  9. 57Fe Moessbauer and magnetic studies of ErFe12-xNbx

    International Nuclear Information System (INIS)

    Wang, J L; Campbell, S J; Cadogan, J M; Tegus, O; Edge, A V J

    2005-01-01

    The structural and magnetic properties of ErFe 12-x Nb x compounds (x 0.6, 0.7 and 0.8) have been investigated by x-ray diffraction, ac susceptibility and dc magnetization measurements and 57 Fe Moessbauer spectroscopy. Refinements of the x-ray diffraction patterns show that the Nb atoms preferentially occupy the 8i sites; this can be understood in the terms of enthalpy effects and differences in the metallic radii. The average Fe-Fe distance at the different sites is found to behave as d Fe-Fe (8i)> d Fe-Fe (8j)> d Fe-Fe (8f). The unit cell volume increases slightly with increasing Nb content, consistent with the larger radius of Nb compared with Fe. A spin reorientation from easy-axis at room temperature to easy-cone at low temperatures has been detected for all compounds. The spin reorientation temperatures T sr in ErFe 12-x Nb x compounds remain essentially unchanged (T sr ∼42-44 K) with increasing Nb concentration, whereas a significant decrease in T sr (T sr1 ∼236-204 K; T sr2 ∼154-94 K) is obtained in DyFe 12-x Nb x from x = 0.6 to 0.8. This can be understood by taking the different crystal-field terms responsible for the spin reorientation in the two systems into account. We find that the spin-reorientation process is particularly sensitive to the sixth-order term B 60 O 60 of the crystal field acting on the Er 3+ ion, due to its large and positive value of γ J . 57 Fe hyperfine interaction parameters and magnetic moments values have been determined for the 8i, 8j and 8f sites from the Moessbauer spectra. The weighted average 57 Fe hyperfine field values were found to follow a T 2 dependence; this suggests that a single-particle excitation mechanism is responsible for reduction of the 3d-sublattice magnetization with increasing temperature

  10. The effect of Nb and Zr addition on the microstructural features and magnetic properties of Tb0.3Dy0.7Fe1.95

    International Nuclear Information System (INIS)

    Palit, Mithun; Arout Chelvane, J.; Basumatary, Himalay; Pandian, S.; Chandrasekaran, V.

    2009-01-01

    Alloys of Tb 0.3 Dy 0.7 Fe 1.95-x Nb x and Tb 0.3 Dy 0.7 Fe 1.95-x Zr x , with x = 0-0.075, were prepared by conventional melting and casting under vacuum. The magnetostriction improved remarkably with the individual addition of Nb and Zr. It is seen from the microstructural features that Nb addition results in the formation of NbFe 2 as the primary phase while Zr addition results in the depletion of (Tb,Dy)Fe 3 phase owing to the substitution of Zr for rare earths in the main phase

  11. History-dependent thermal expansion in NbO{sub 2}F

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Josefsberg, Ryan E.; Gallington, Leighanne C.; Morelock, Cody R.; Monaco, Christopher M. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States)

    2014-05-01

    Materials with cubic ReO{sub 3}-type structures are of interest for their low or negative thermal expansion characteristics. TaO{sub 2}F is known to display almost zero thermal expansion over a wide temperature range. On heating NbO{sub 2}F, its volume coefficient of thermal expansion decreases from ∼+45 ppm K{sup −1} at 100 K to almost zero at 400 K. NbO{sub 2}F is cubic between 100 and 500 K. Samples of “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying contain hydroxyl defects and metal vacancies. On heating, they can undergo irreversible chemical changes while maintaining a cubic ReO{sub 3}-type structure. The possibility of hydroxyl defect incorporation should be considered when preparing oxyfluorides for evaluation as battery materials. - Graphical abstract: “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in HF contains cation vacancies and hydroxyl groups. It undergoes irreversible changes on heating to low temperatures, unlike NbO{sub 2}F prepared by the solid state reaction of Nb{sub 2}O{sub 5} and NbF{sub 5}. - Highlights: • The digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying does not produce NbO{sub 2}F. • The ReO{sub 3}-type product from the HF digestion of Nb{sub 2}O{sub 5} contains metal vacancies and hydroxyl. • The thermal expansion coefficient of NbO{sub 2}F decreases on heating and approaches zero at ∼400 K.

  12. Development of crystal texture in R-lean RFeCoNbB (R = Nd, Pr) alloy during melt spinning processes

    International Nuclear Information System (INIS)

    Li, Wei; Li, Lanlan; Liu, Yanguo; Zhang, Xiangyi

    2012-01-01

    Highlights: ► We study the texture development during the melt spinning processes of R-lean alloys. ► A strong (0 0 l) texture parallel to the ribbon plane for (Nd,Pr) 2 Fe 14 B is obtained. ► The texture for R 2 Fe 14 B crystals can develop by a seeding effect of α-Fe texture. ► The anisotropic nanocomposite magnet yields M r = 0.78M s and large (BH) max = 25.2 MGOe. - Abstract: The formation of crystal texture of R 2 Fe 14 B nanocrystals in R–Fe–B (R = rare earth) alloys with low R content ( 2 Fe 14 B nanocrystals during the melt spinning processes of Nd 3.6 Pr 5.4 Fe 80 Co 3 NbB 7 by effectively employing the seeding effect of α-Fe nanocrystal texture. The (Nd,Pr) 2 Fe 14 B nanocrystals produced from the R-lean alloy at a wheel speed of 18 m/s show a strong (0 0 l) texture parallel to the ribbon plane, which yields a high remanence M r = 0.78M s and a large energy product (BH) max = 25.2 MGOe for the α-Fe/(Nd,Pr) 2 Fe 14 B nanocomposite ribbons. The present study provides a promising approach to prepare anisotropic nanocomposite magnets from R-lean alloys.

  13. Behaviour at the indicator scale of the elements Zr, Hf and 104, Nb,Ta and Pa (105) in very complexation media; Comportement a l`echelle des indicateurs des elements Zr, Hf, et 104, Nb, Ta, et Pa (105) en milieux tres complexants

    Energy Technology Data Exchange (ETDEWEB)

    Monroy Guzman, F. [Institut de Physique Nucleaire, CNRS - IN2P3 Universite Paris Sud, 91406 Orsay Cedex (France)

    1997-12-31

    In order to determine the chemical properties of the trans-actinide elements of Z = 104 and 105 in aqueous solutions we studied their behaviour to ion exchange resin in different complex media. Due to the very short lifetimes (some tens of seconds) et to the low yield of these elements (a few atoms per irradiation hour) only very fast radiochemical techniques can be used. These severe constraints impose comparative studies of these elements with their most likely homologues to be carried out. The corresponding homologues were the elements of group 4 (Zr and Hf) for the element 104 and the elements of group 5 (Nb and Ta) and also Pa for the element 105. The complexation properties of the elements at indicator scale were determined in the media of HF, NH{sub 4}/HClO{sub 4}, NH{sub 4}SCN/HClO{sub 4}, NH{sub 4}SCN/HF and HCl/HF by ion exchange chromatography. The studies in fluorides media allowed us to identify the complexes in solution and to explain the shape of the experimentally observed sorption curves. The decrease of sorption for higher acid concentration in case of HF/HCl medium was interpreted by formation of chloro-fluoro-complexes. In case of the mixture NH{sub 4}SCN/HF, the particularly pronounced anti-synergic effects were observed and discussed. At the same time studies of the Hf and Ta short-lived isotopes were carried out by means of the RACHEL facility operating by the Orsay Tandem accelerator. These realistic simulations allowed optimization of different production, transportation and separation stages of the trans-actinide elements. The two experiments of 104 element production showed that this element forms in HF very stable anionic complexes similarly to its homologues Zr and Hf. (authors). 181 refs.

  14. Behaviour at the indicator scale of the elements Zr, Hf and 104, Nb,Ta and Pa (105) in very complexation media; Comportement a l`echelle des indicateurs des elements Zr, Hf, et 104, Nb, Ta, et Pa (105) en milieux tres complexants

    Energy Technology Data Exchange (ETDEWEB)

    Monroy Guzman, F [Institut de Physique Nucleaire, CNRS - IN2P3 Universite Paris Sud, 91406 Orsay Cedex (France)

    1998-12-31

    In order to determine the chemical properties of the trans-actinide elements of Z = 104 and 105 in aqueous solutions we studied their behaviour to ion exchange resin in different complex media. Due to the very short lifetimes (some tens of seconds) et to the low yield of these elements (a few atoms per irradiation hour) only very fast radiochemical techniques can be used. These severe constraints impose comparative studies of these elements with their most likely homologues to be carried out. The corresponding homologues were the elements of group 4 (Zr and Hf) for the element 104 and the elements of group 5 (Nb and Ta) and also Pa for the element 105. The complexation properties of the elements at indicator scale were determined in the media of HF, NH{sub 4}/HClO{sub 4}, NH{sub 4}SCN/HClO{sub 4}, NH{sub 4}SCN/HF and HCl/HF by ion exchange chromatography. The studies in fluorides media allowed us to identify the complexes in solution and to explain the shape of the experimentally observed sorption curves. The decrease of sorption for higher acid concentration in case of HF/HCl medium was interpreted by formation of chloro-fluoro-complexes. In case of the mixture NH{sub 4}SCN/HF, the particularly pronounced anti-synergic effects were observed and discussed. At the same time studies of the Hf and Ta short-lived isotopes were carried out by means of the RACHEL facility operating by the Orsay Tandem accelerator. These realistic simulations allowed optimization of different production, transportation and separation stages of the trans-actinide elements. The two experiments of 104 element production showed that this element forms in HF very stable anionic complexes similarly to its homologues Zr and Hf. (authors). 181 refs.

  15. Effect of Mo-Fe substitution on glass forming ability, thermal stability, and hardness of Fe-C-B-Mo-Cr-W bulk amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, Hesham E.; Cheney, Justin L. [University of California, San Diego Materials Science and Engineering Program, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States); Vecchio, Kenneth S. [University of California, San Diego Department of NanoEngineering, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: kvecchio@ucsd.edu

    2008-08-25

    Amorphous Fe{sub 67-x}C{sub 10}B{sub 9}Mo{sub 7+x}Cr{sub 4}W{sub 3} (x = 1-7 at.%) plates with 640 {mu}m thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry (DSC), differential thermal analysis, and X-ray diffractometry (XRD). The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe{sub 62}C{sub 10}B{sub 9}Mo{sub 12}Cr{sub 4}W{sub 3} is the best glass former in this study, demonstrating a supercooled liquid region, {delta}T{sub x} = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three-phase evolution during crystallization. A second set of heat treatments was performed to identify each phase. Hardness data was collected at each of the heat treatment conditions, and a bulk metallic glasses (BMG)-derived composite containing a Mo-rich phase exhibited Vickers Hardness in excess of 2000. The fully amorphous alloys had an average hardness approaching 1500.

  16. 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

  17. Influence of alloying element of corrosion of Zr-Nb-Sn-Fe-Cu alloy and impedance characteristics of its oxide layer

    International Nuclear Information System (INIS)

    Park, S. Y.; Lee, M. H.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.

    2000-01-01

    As a part of the advanced Zr fuel cladding development program, the autoclave corrosion test was performed on the series of Zr-0.2Nb-1.1Sn-Fe-Cu and Zr-0.4Nb-0.8Sn-Fe-Cu alloys in 70 ppm LiOH solution at 360 .deg. C. The oxide characteristics were investigated by using the Electrochemical Impedance Spectroscope(EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of main alloying elements such as Nb, Sn, Fe and Cu. The equivalent circuit was composed as a result of the spectrum from EIS measurements on the oxide layer that formed at pro- and post-transition regions. By using the capacitance characteristics of equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results

  18. Magnetic regimes in amorphous Ni--Fe--P--B alloys

    International Nuclear Information System (INIS)

    Durand, J.

    1976-10-01

    A complete substitution of iron for nickel was obtained by splat-cooling in amorphous alloys of composition (Ni/sub 100-y/Fe/sub y/) 79 P 13 B 8 . Results of high-field magnetization (up to 70 kOe), ac and dc low-field susceptibility, Curie temperature, and resistivity measurements over a temperature range of 1.7 to 300 0 K are reported. The Ni 79 P 13 B 8 alloy is not ferromagnetic, but the magnetization behavior as a function of field and temperature is typically that of alloys in the critical concentration range for ferromagnetism. The Fe 79 P 13 B 8 alloy is ferromagnetic with a Curie temperature T/sub c/ of 616 0 K. For y = 1 at. percent, the Fe atoms are magnetic. The variation of the moment per Fe atom as a function of y is discussed. When y is increased, the Ni atoms are likely to be polarized progressively and the moment per Ni atom would be roughly constant for y equal to or greater than 30 at. percent. Various magnetic behaviors were defined as a function of the Fe content. The value of T/sub c/ reaches a maximum for y similarly ordered 90 at. percent and extrapolates to zero for y similarly ordered 7 at. percent. Alloys within the range 1 equal to or less than y equal to or less than 10 at. percent did not exhibit well-defined Curie transition, but sharp maxima in low-field susceptibility measurements were observed at T/sub M/. The value of T/sub M/ is proportional to y for 1 equal to or less than y equal to or less than 4 at. percent, as in classical spin-glass regimes. For 4 less than y equal to or less than 10 at. percent, the variation of T/sub M/ as a function of y implies a more complicated type of magnetic ordering (micromagnetism or superparamagnetism). Homogeneous ferromagnetic ordering emerges only for y greater than 10 at. percent. Results of resistivity measurements are discussed in relation to the magnetic properties of different regimes in the magnetic phase diagram. 6 figures, 2 tables

  19. Effect of interfacial SiO2- y layer and defect in HfO2- x film on flat-band voltage of HfO2- x /SiO2- y stacks for backside-illuminated CMOS image sensors

    Science.gov (United States)

    Na, Heedo; Lee, Jimin; Jeong, Juyoung; Kim, Taeho; Sohn, Hyunchul

    2018-03-01

    In this study, the effect of oxygen gas fraction during deposition of a hafnium oxide (HfO2- x ) film and the influence of the quality of the SiO2- y interlayer on the nature of flat-band voltage ( V fb) in TiN/HfO/SiO2- y /p-Si structures were investigated. X-ray photoemission spectroscopy analysis showed that the non-lattice oxygen peak, indicating an existing oxygen vacancy, increased as the oxygen gas fraction decreased during sputtering. From C- V and J- E analyses, the V fb behavior was significantly affected by the characteristics of the SiO2- y interlayer and the non-lattice oxygen fraction in the HfO2- x films. The HfO2- x /native SiO2- y stack presented a V fb of - 1.01 V for HfO2- x films with an oxygen gas fraction of 5% during sputtering. Additionally, the V fb of the HfO2- x /native SiO2- y stack could be controlled from - 1.01 to - 0.56 V by changing the deposition conditions of the HfO2- x film with the native SiO2- y interlayer. The findings of this study can be useful to fabricate charge-accumulating layers for backside-illuminated image sensor devices.

  20. Substitution of Nb doping on the structural, microstructural and electrical properties in PZT films

    International Nuclear Information System (INIS)

    Haccart, T.; Remiens, D.; Cattan, E.

    2003-01-01

    Undoped and niobium (Nb) doped Pb 1-y (Zr 0.54 Ti 0.46 ) 1-y Nb y O 3 have been deposited by sputtering on Pt metallized silicon substrates. The niobium concentration, y, was varied from 1 to 7 at.% by 1 at.%. The Zr/Ti ratio was fixed to 54/46 corresponding to the Morphotropic Phase Boundary. Structural, microstructural, and electrical properties were evaluated depending on Nb content. The films (doped and undoped) present a (1 1 1)-preferred orientation. The Nb doping induces an increase of the grain size and as it was observed in bulk materials the dielectric constant (ε r ) and the piezoelectric coefficients (e 31 and d 33 ) reach their maximum for low Nb concentration (2 at.%). The remnant and the maximum polarizations increase as the coercive field decreased slightly with the Nb concentration. The internal electric field increases with Nb content; as a result, the 'self-polarization' of the films (polarization measured without poling treatment) is enhanced with niobium substitution. In term of fatigue behavior, it was found that switching endurance characteristics are maximum for low Nb doping level

  1. Substitution of Nb doping on the structural, microstructural and electrical properties in PZT films

    Energy Technology Data Exchange (ETDEWEB)

    Haccart, T.; Remiens, D.; Cattan, E

    2003-01-15

    Undoped and niobium (Nb) doped Pb{sub 1-y}(Zr{sub 0.54}Ti{sub 0.46}){sub 1-y}Nb{sub y}O{sub 3} have been deposited by sputtering on Pt metallized silicon substrates. The niobium concentration, y, was varied from 1 to 7 at.% by 1 at.%. The Zr/Ti ratio was fixed to 54/46 corresponding to the Morphotropic Phase Boundary. Structural, microstructural, and electrical properties were evaluated depending on Nb content. The films (doped and undoped) present a (1 1 1)-preferred orientation. The Nb doping induces an increase of the grain size and as it was observed in bulk materials the dielectric constant ({epsilon}{sub r}) and the piezoelectric coefficients (e{sub 31} and d{sub 33}) reach their maximum for low Nb concentration (2 at.%). The remnant and the maximum polarizations increase as the coercive field decreased slightly with the Nb concentration. The internal electric field increases with Nb content; as a result, the 'self-polarization' of the films (polarization measured without poling treatment) is enhanced with niobium substitution. In term of fatigue behavior, it was found that switching endurance characteristics are maximum for low Nb doping level.

  2. Phosphorus-containing enamel type coatings on metals

    International Nuclear Information System (INIS)

    Sedmale, G.; Sedmalis, U.; Kpbjakov, V.

    1998-01-01

    Experimental data are given on development of temperature resistant glassy electroinsulating coatings for two groups of metals: niobium and its alloys and metals of the Fe-Co group. The development of the coatings is based on the system: BaO-B 2 O 3 (Al 2 O 3 )-SiO 2 -P 2 O 5 with content of P 2 O 5 up to 30 mol %. The formation process of coatings on metals proceeds via formation of intermediate layer with thickness of 4-6 m u m , which in the case of Nb-Zr coatings consists of dense crystalline aggregates, whose composition according to the x-ray phase analysis corresponds to NbP, Al 9 Nb,AlPO 4 , NbPO 3 . In the case Co-Fe alloys the intermediate layer is amorphous, the content of crystalline phases (CoFe 2 O 4 , Fe 2 O 3 ) is low (not more than 10 %). The latter does not significantly influence the magnetic properties of material and provides the electrical insulation at 550-666 deg C. In the case of protective coatings for Nb-Zr metals the formed intermediate layer and glassy surface layer (their total thickness being 40-60 m u m ) provide protection of the metals up to 1000 deg C in the period up to 1000 h. (author)

  3. Characterization of the Nb-B superlattice system

    Energy Technology Data Exchange (ETDEWEB)

    Franco, D.G.; Sarmiento-Chavez, A.; Schenone, N.; Llacsahuanga Allcca, A.E.; Gómez Berisso, M.; Fasano, Y.; Guimpel, J., E-mail: jguimpel@cab.cnea.gov.ar

    2016-12-15

    Highlights: • In this manuscript we study the crystalline and superconducting properties of this system, as a possible material to be used in solid state neutron detector sensors. • The results show that this superlattice system can be grown even for very thin layers, in spite of the Nb-B binary system showing many possible compounds, which could enhance interdifussion at the interfaces. • Also, the superconducting properties are not degraded, and they are even enhanced with respect to those of single Nb films of the same thickness. • In conclusion, we find that this system is a good potential candidate for the design and construction of solid state neutron Transition Edge Sensors. - Abstract: We study the growth, stacking and superconducting properties of Nb and B thin films and superlattices. The interest in these resides in their possible use in transition edge neutron sensors. The samples were grown by magnetron sputtering over Si (1  0  0) substrates. The X-ray diffraction patterns for all Nb containing samples show a Nb (1  1  0) preferential orientation. From the low-angle X-ray reflectivity we obtain information on the superlattice structure. The superconducting transition temperatures of the superlattices, obtained from the temperature dependence of the magnetization, are higher than those of single Nb films of similar thickness. The temperature dependence of the perpendicular and parallel upper critical fields indicate that the superlattices behave as an array of decoupled superconducting Nb layers.

  4. Characterization of the Nb-B superlattice system

    International Nuclear Information System (INIS)

    Franco, D.G.; Sarmiento-Chavez, A.; Schenone, N.; Llacsahuanga Allcca, A.E.; Gómez Berisso, M.; Fasano, Y.; Guimpel, J.

    2016-01-01

    Highlights: • In this manuscript we study the crystalline and superconducting properties of this system, as a possible material to be used in solid state neutron detector sensors. • The results show that this superlattice system can be grown even for very thin layers, in spite of the Nb-B binary system showing many possible compounds, which could enhance interdifussion at the interfaces. • Also, the superconducting properties are not degraded, and they are even enhanced with respect to those of single Nb films of the same thickness. • In conclusion, we find that this system is a good potential candidate for the design and construction of solid state neutron Transition Edge Sensors. - Abstract: We study the growth, stacking and superconducting properties of Nb and B thin films and superlattices. The interest in these resides in their possible use in transition edge neutron sensors. The samples were grown by magnetron sputtering over Si (1  0  0) substrates. The X-ray diffraction patterns for all Nb containing samples show a Nb (1  1  0) preferential orientation. From the low-angle X-ray reflectivity we obtain information on the superlattice structure. The superconducting transition temperatures of the superlattices, obtained from the temperature dependence of the magnetization, are higher than those of single Nb films of similar thickness. The temperature dependence of the perpendicular and parallel upper critical fields indicate that the superlattices behave as an array of decoupled superconducting Nb layers.

  5. XYO{sub 3} (X = K, Na; Y = Nb, Ta) based superlattices for photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guang-Zhao; Chen, Xiao-Rui; Yuan, Hong-Kuan; Kuang, An-Long [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Chen, Hong [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2017-05-15

    The photocatalytic activities of XYO{sub 3} (X = K, Na; Y = Ta, Nb) and XYO{sub 3}/X1Y1O{sub 3} (X, X1 = K, Na; Y, Y1 = Ta, Nb) systems are investigated by using hybrid density functional. All the XYO{sub 3} and XYO{sub 3}/X1Y1O{sub 3} systems are indirect band gap semiconductors, and the band gap of KNbO{sub 3}/KTaO{sub 3} is smaller than those of KNbO{sub 3} and KTaO{sub 3}, while the band gaps of KNbO{sub 3}/NaNbO{sub 3}, KNbO{sub 3}/NaTaO{sub 3}, KTaO{sub 3}/NaNbO{sub 3}, KTaO{sub 3}/NaTaO{sub 3}, and NaNbO{sub 3}/NaTaO{sub 3} are respectively between the band gaps of these two crystals which make up these superlattices. The electronic structure of KNbO{sub 3}/NaTaO{sub 3} is the same as that of KTaO{sub 3}/NaNbO{sub 3} since both have the same component and similar crystal structure. The band edges of all the considered superlattices are thermodynamically allowed for the water reduction and oxidation processes, and therefore, they could be used for photocatalytic water splitting. Band structures for (i) KNbO{sub 3}/KTaO{sub 3}, (ii) KNbO{sub 3}/NaNbO{sub 3}, (iii) KNbO{sub 3}/NaTaO{sub 3}, (iv) KTaO{sub 3}/NaNbO{sub 3}, (v) KTaO{sub 3}/NaTaO{sub 3}, and (vi) NaNbO{sub 3}/NaTaO{sub 3} superlattices. The horizontal dashed lines represent the Fermi levels. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Feasibility study of electrophoresis deposition of DyF3 on Nd-Fe-B particles for coercivity enhancement

    Science.gov (United States)

    Kim, K. M.; Kang, M. S.; Kwon, H. W.; Lee, J. G.; Yu, J. H.

    2018-05-01

    Feasibility of the electrophoresis deposition (EPD) technique for homogeneous and adhesive deposition of DyF3 particles on the Nd-Fe-B-type particles was studied, and coercivity enhancement in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD was investigated. HDDR-treated Nd12.5Fe80.6B6.4Ga0.3Nb0.2 particles were deposited with DyF3 particles by EPD. More homogeneous and adhesive deposition of DyF3 particles on the surface of Nd-Fe-B particles was made by the EPD with respect to conventional dip-coating, and this led to more active and homogeneous diffusion of Dy. More profound coercivity enhancement was achieved in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD compared to dip-coated particles.

  7. Structural and Moessbauer Effect Studies of 0.7Bi0.95Dy0.05FeO3-0.3Pb(Fe0.5Nb0.5)O3 Multiferroic

    International Nuclear Information System (INIS)

    Stoch, A.; Kulawik, J.; Stoch, P.; Maurin, J.; Zachariasz, P.

    2011-01-01

    0.7Bi 0.95 Dy 0.05 FeO 3 -0.3Pb(Fe 0.5 Nb 0.5 )O 3 is a multiferroic material which exhibits ferroelectric and antiferromagnetic ordering. In this paper the way of the synthesis of 0.7Bi 0.95 Dy 0.05 FeO 3 -0.3Pb(Fe 0.5 Nb 0.5 )O 3 is presented. The detailed X-ray and Moessbauer effect studies were done and crystal and hyperfine interaction parameters were obtained. (authors)

  8. Unidirectional solidification of a Nbss/Nb5Si3 in-situ composite

    International Nuclear Information System (INIS)

    Guo, X.P.; Ding, X.; Zhang, J.; Fu, H.Z.; Guan, P.; Kusabiraki, K.

    2005-01-01

    The directionally solidified specimens of Nb-13.52 Si-22.60 Ti-6.88 Hf-2.54 Cr-2.24 Al alloy were prepared in an electron beam floating zone melting furnace at the withdrawing rate of 0.1, 0.3, 0.6, 1.0, 2.4 and 6.0 mm/min. All the primary Nb solid solution (Nb ss ) columns, Nb ss + (Nb) 3 Si/(Nb) 5 Si 3 eutectic colonies and divorced (Nb) 3 Si/(Nb) 5 Si 3 plates or chains align well along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the microstructure is gradually refined, and the amount of Nb ss + (Nb) 3 Si/(Nb) 5 Si 3 eutectic colonies increases. Both the room temperature ultimate tensile strength σ b and fracture toughness K Q are improved for the directionally solidified specimens. The tensile fracture occurs in a cleavage way. (orig.)

  9. Novel high-strength Fe-based composite materials with large plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Werniewicz, Katarzna; Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Siegel, Uwe; Bartusch, Birgit; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering (Poland)

    2007-07-01

    Among glass-forming alloy systems reported so far, Fe-based bulk metallic glasses play a special role. Compared to other amorphous alloys e.g. Zr-, Ti-based, such glasses show superior mechanical strength. However, due to the general brittleness their wider application as structural materials is strongly restricted. The alternative approach to overcome this defect is to design BMG composites. In this work we present a series of new Fe-Cr-Mo-Ga-(Si,C) composite materials derived from an Fe-Cr-Mo-Ga-C-P-B glassy alloy, with the aim to improve the ductility of this high-strength material. The effect of the composition and the phase formation on the resulting mechanical properties was investigated. It has been found that the formation of a complex microstructure, which essentially consists of soft Ga-rich dendrites embedded in a hard Cr- and Mo-rich matrix, leads to a material with excellent compressive mechanical properties. While the obtained values of true strength are comparable with data reported for Fe-Cr-Mo-Ga-C-P-B BMG, the values of true strain are greatly improved for investigated composites.

  10. Effect of magnetic field frequency on coercivity behavior of nanocrystalline Fe79Hf7B12Si2 glass-coated microwires

    International Nuclear Information System (INIS)

    Garcia, C.; Zhukova, V.; Gonzalez, J.; Blanco, J.M.; Zhukov, A.

    2008-01-01

    Dependence of coercitivy, H c , on AC magnetic field frequency, f, has been studied in glass coated Fe 79 Hf 7 B 12 Si 2 microwires exhibiting nanocrystalline structure. Annealing of the samples at 450-600 deg. C changes its structure and consequently the magnetic properties (coercivity and magnetostriction constant). The grain size of the nanocrystals increases from about 17 nm up to 35 nm after annealing at 600 deg. C. For the as-prepared microwires the frequency dependence fits well to √(f). In annealed at 550 deg. C samples H c ∼f 2/3 dependence is observed. In terms of the interpretation of the domain wall propagation, both kind of H c (f) dependences can be interpreted considering depinned domain walls, i.e. neglecting elastic coefficient K of the domain wall motion equation. The H c ∼√(f) corresponds better to low frequency limits while H c ∼f 2/3 is attributed to the high frequency behavior

  11. Analysis of physical and magnetic properties of composite NdFeB bind with polyvinyl alcohol

    Science.gov (United States)

    Ramlan; Sardjono, P.; Muljadi; Setiabudidaya, D.; Gulo, F.

    2018-03-01

    The composite magnet NdFeB has been made using magnetic powder MQP-B and polyvinyl alcohol (PVA) as the binder. The mixing compositions of raw materials used are: 95 wt% NdFeB - 5 wt% PVA, 92.5 wt% NdFeB - 7.5 wt% PVA, 90 wt.% NdFeB - 10 wt% PVA, and 87.5 wt% NdFeB - 12.5 wt% PVA. Both raw materials are weighed according to the composition, and then mixed until homogeneous. Furthermore, pellet forming was made using dry pressing at 50 kgf/cm2 pressures and continued with drying at 100 °C and 10 mmbar for 4 hours. The characterization includes bulk density, hardness, compressive strength measurements, and magnetic properties testing. The characterization results show that the optimal composition of binder PVA is achieved at 5–7.5 wt% NdFeB composite magnet with following properties: bulk density = 5.21–5.25 g/cm3, hardness = 302.17 - 304.32 Hv, compressive strength = 25.17–3.17 kgf/cm2, magnetic flux = 1150-1170 Gauss, remanence = 70.90–74.97 emu/g or 4.7–5.0 kGauss, coercivity = 8.68–8.76 kOe, and energy product = 2.89–3.04 MgOe.

  12. Large Magnetic Anisotropy in HfMnP

    Science.gov (United States)

    Parker, David; Lamichhane, Tej; Taufour, Valentin; Masters, Morgan; Thimmaiah, Srinivasa; Bud'Ko, Ser'gey; Canfield, Paul

    We present a theoretical and experimental study of two little-studied manganese phosphide ferromagnets, HfMnP and ZrMnP, with Curie temperatures above room temperature. We find an anisotropy field in HfMnP approaching 10 T - larger than that of the permanent magnet workhorse NdFeB magnets. From theory we determine the source of this anisotropy. Our results show the potential of 3d-element-based magnetic materials for magnetic applications.

  13. Corrosion resistance of Fe-based amorphous alloys

    International Nuclear Information System (INIS)

    Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

    2014-01-01

    Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

  14. TbNb6Sn6: the first ternary compound from the rare earth–niobium–tin system

    Directory of Open Access Journals (Sweden)

    Viktor Hlukhyy

    2010-12-01

    Full Text Available The title compound, terbium hexaniobium hexastannide, TbNb6Sn6, is the first ternary compound from the rare earth–niobium–tin system. It has the HfFe6Ge6 structure type, which can be analysed as an intergrowth of the Zr4Al3 and CaCu5 structures. All the atoms lie on special positions; their coordination geometries and site symmetries are: Tb (dodecahedron 6/mmm; Nb (distorted icosahedron 2mm; Sn (Frank–Caspar polyhedron, CN = 14–15 6mm and overline{6}m2; Sn (distorted icosahedron overline{6}m2. The structure contains a graphite-type Sn network, Kagome nets of Nb atoms, and Tb atoms alternating with Sn2 dumbbells in the channels.

  15. Densification and properties of HfB2 based materials

    International Nuclear Information System (INIS)

    Sonber, J.K.; Ch Murthy, T.S.R.; Bedse, R.D.; Subramanian, C.; Kumar, Sunil; Fotedar, R.K.; Krishnamurthy, N.; Suri, A.K.

    2011-01-01

    This paper presents the results of investigation carried out on densification and properties of HfB 2 based materials. Densification study of HfB 2 with and without sinter additive was carried out by hot pressing. TiSi 2 and CrSi 2 were used as sinter additive. Monolithic HfB 2 was densified to only 80%ρ th at 1850 deg C with a pressure of 35 MPa. Addition of 10 wt% TiSi 2 resulted in a density of 95% TD at a relatively low temperature of 1650 deg C and a low pressure of 20 MPa. Addition of 10% CrSi 2 resulted in a density of 99% TD at the same operating conditions. All the samples were characterized by SEM/EDS and mechanical property measurement. (author)

  16. Scaling analysis of [Fe(pyrazole)4]2[Nb(CN)8] molecular magnet

    International Nuclear Information System (INIS)

    Konieczny, P.; Pełka, R.; Zieliński, P.M.; Pratt, F.L.; Pinkowicz, D.; Sieklucka, B.; Wasiutyński, T.

    2013-01-01

    The critical behaviour of the three dimensional (3D) molecular magnet {[Fe II (pirazol) 4 ] 2 [Nb IV (CN) 8 ]·4H 2 O} n has been studied with the use of experimental techniques such as ac magnetometry and zero field μSR spectroscopy. The sample orders magnetically below T c =7.8 K. The measurements allowed to determine static exponents β, γ, and the dynamic exponent w. The resulting exponent values indicate that the studied system belongs to the universality class of the 3D Heisenberg model. - Highlights: • The critical behaviour of {[Fe II (pirazol) 4 ] 2 [Nb IV (CN) 8 ]∙4H 2 O} n has been studied. • Critical exponents β, γ, and w were obtained from ac magnetometry and ZF µSR data. • All obtained values of critical exponents are close to the 3D Heisenberg model

  17. Coexistence of 3d-ferromagnetism and superconductivity in (Li{sub 1-x}Fe{sub x}OH)(Fe{sub 1-y}Li{sub y}Se)

    Energy Technology Data Exchange (ETDEWEB)

    Brueckner, Felix; Sarkar, Rajib; Kamusella, Sirko; Klauss, Hans-Henning [Institut fuer Festkoerperphysik, Technische Universitaet Dresden (Germany); Luetkens, Hubertus [Paul-Scherrer-Institut, Villigen (Switzerland); Pachmayr, Ursula; Nitsche, Fabian; Johrendt, Dirk [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

    2015-07-01

    In the family of iron-based superconductors, where the superconducting dome is usually separated from the magnetic phase, only few compounds show ferromagnetism arising in the superconducting state. The so far discovered examples show ferromagnetic ordering of Eu{sup 2+} ions. In this context, the presented ordering of iron orbitals in (Li{sub 1-x}Fe{sub x}OH)(Fe{sub 1-y}Li{sub y}Se) is unique. We performed a wealth of experimental methods to characterize the physics in this system, including dc resistivity and magnetization. With use of local probes (μSR,NMR,Moessbauer), we are able to describe the emergence of bulk ferromagnetism and superconductivity in a microscopic scale. Both phenomena can coexist, though they compete with each other, due to a spatial separation in the multilayer system.

  18. Corrosion fatigue studies on a bulk glassy Zr-based alloy under three-point bending

    Science.gov (United States)

    Grell, Daniel; Wilkin, Yannic; Gostin, Petre F.; Gebert, Annett; Kerscher, Eberhard

    2016-12-01

    Corrosion fatigue (CF) tests were carried out on bulk glassy Zr52.5Cu17.9Al10Ni14.6Ti5 (Vitreloy 105) samples under load-controlled three-point bending conditions with a load ratio of R = 0.1 in 0.01 M Na2SO4 + 0.01 M NaCl electrolyte. During cyclic testing, the bar-shaped specimens were polarized in situ at constant potentials and the current was monitored. Three different anodic potentials within the interval between the pitting potential EP and the repassivation potential ER, and three different load amplitudes were applied. In some cases, in situ microscopic observations revealed the formation of black corrosion products in the vicinity of the crack tip during anodic polarization. Fractographic analysis revealed a clear distinction between two modes of crack growth characterized by smooth dissolution induced regions on the one hand and slim fast fracture areas on the other hand. Both alternating features contributed to a broad striated corrosion fatigue fracture surface. Moreover, further fatigue tests were carried out under free corrosion conditions yielding additional information on crack initiation and crack propagation period by means of the open circuit potential (OCP) changes. Thereby, a slight increase in OCP was detected after rupture of the passive layer due to bare metal exposed to the electrolyte. The electrochemical response increased continuously according to stable crack propagation until fracture occurred. Finally, the fracture surfaces of the corrosion fatigue samples were investigated by energy dispersive X-ray with the objective of analyzing the elemental distribution after anodic dissolution. Interestingly, anodic polarization at a near repassivation potential of -50 mV vs. SCE (Saturated Calomel Electrode, E = 0.241 V vs. SHE, Standard Hydrogen Electrode) led to favorable effects on the fatigue lifetime. In conclusion, all results are conflated to a corrosion fatigue model for bulk glassy Vitreloy 105 under anodic polarization in chloride

  19. Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, A.S.; Buznikov, N.A. E-mail: n_buznikov@mail.ru; Granovsky, A.B.; Iakubov, I.T.; Prokoshin, A.F.; Rakhmanov, A.L.; Yakunin, A.M

    2002-08-01

    The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC current is studied. The frequency spectrum of a voltage induced in a pick-up coil wound around the wire is analyzed. The frequency spectrum is shown to consist of even harmonics within a wide range of AC current amplitudes and longitudinal DC magnetic fields. The strong dependencies of the harmonic amplitudes on the DC field are found. The results obtained may be of importance for the design of weak magnetic field sensors.

  20. Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires

    International Nuclear Information System (INIS)

    Antonov, A.S.; Buznikov, N.A.; Granovsky, A.B.; Iakubov, I.T.; Prokoshin, A.F.; Rakhmanov, A.L.; Yakunin, A.M.

    2002-01-01

    The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC current is studied. The frequency spectrum of a voltage induced in a pick-up coil wound around the wire is analyzed. The frequency spectrum is shown to consist of even harmonics within a wide range of AC current amplitudes and longitudinal DC magnetic fields. The strong dependencies of the harmonic amplitudes on the DC field are found. The results obtained may be of importance for the design of weak magnetic field sensors

  1. A method for increasing the homogeneity of the temperature distribution during magnetic fluid hyperthermia with a Fe-Cr-Nb-B alloy in the presence of blood vessels

    Science.gov (United States)

    Tang, Yundong; Flesch, Rodolfo C. C.; Jin, Tao

    2017-06-01

    Magnetic hyperthermia ablates tumor cells by absorbing the thermal energy from magnetic nanoparticles (MNPs) under an external alternating magnetic field. The blood vessels (BVs) within tumor region can generally reduce treatment effectiveness due to the cooling effect of blood flow. This paper aims to investigate the cooling effect of BVs on the temperature field of malignant tumor regions using a complex geometric model and numerical simulation. For deriving the model, the Navier-Stokes equation for blood flow is combined with Pennes bio-heat transfer equation for human tissue. The effects on treatment temperature caused by two different BV distributions inside a mammary tumor are analyzed through numerical simulation under different conditions of flow rate considering a Fe-Cr-Nb-B alloy, which has low Curie temperature ranging from 42 °C to 45 °C. Numerical results show that the multi-vessel system has more obvious cooling effects than the single vessel one on the temperature field distribution for hyperthermia. Besides, simulation results show that the temperature field within tumor area can also be influenced by the velocity and diameter of BVs. To minimize the cooling effect, this article proposes a treatment method based on the increase of the thermal energy provided to MNPs associated with the adoption of low Curie temperature particles recently reported in literature. Results demonstrate that this approach noticeably improves the uniformity of the temperature field, and shortens the treatment time in a Fe-Cr-Nb-B system, thus reducing the side effects to the patient.

  2. FTIR and Mössbauer spectroscopic study of sodium–aluminum–iron phosphate glassy materials for high level waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Stefanovsky, S.V., E-mail: serge.stefanovsky@yandex.ru [Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Laboratory of Radioecology and Radiation Problems, Moscow (Russian Federation); Stefanovsky, O.I. [Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Laboratory of Radioecology and Radiation Problems, Moscow (Russian Federation); Remizov, M.B.; Belanova, E.A.; Kozlov, P.V. [FSUE PA Mayak, Central Plant Laboratory, Ozersk, Chelyabinsk Reg. (Russian Federation); Glazkova, Ya.S.; Sobolev, A.V.; Presniakov, I.A. [Lomonosov Moscow State University, Department of Radiochemistry (Russian Federation); Kalmykov, S.N. [Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Laboratory of Radioecology and Radiation Problems, Moscow (Russian Federation); Lomonosov Moscow State University, Department of Radiochemistry (Russian Federation); Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences, Laboratory of Radiochemistry, Moscow (Russian Federation); Myasoedov, B.F. [Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Laboratory of Radioecology and Radiation Problems, Moscow (Russian Federation); Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences, Laboratory of Radiochemistry, Moscow (Russian Federation)

    2015-11-15

    Complex sodium-aluminum-iron phosphate glassy materials with various Al{sub 2}O{sub 3} to Fe{sub 2}O{sub 3} ratio containing high level waste (HLW) surrogate were characterized by X-ray diffraction and scanning electron microscopy and studied in details by Fourier transform infrared (FTIR) spectroscopy. The samples with high Al{sub 2}O{sub 3} content and not containing Fe{sub 2}O{sub 3} were predominantly amorphous but subjected to devitrification under annealing. Addition of B{sub 2}O{sub 3} and partial Fe{sub 2}O{sub 3} substitution for Al{sub 2}O{sub 3} in the materials increases their resistance to devitrification whereas further substitution and NiO incorporation significantly increase the tendency to devitrification. FTIR spectra demonstrate changes in the structure of glassy materials caused by both structural variations in the anionic motif and occurrence of crystalline phases in the materials. According to Mössbauer spectroscopy data, iron in the glassy samples is present as octahedrally coordinated Fe{sup 3+} ions while in the partly devitrified samples iron is partitioned among vitreous and crystalline phases entering the vitreous phase mainly as Fe{sup 3+}O{sub 6} units and crystalline phases as major Fe{sup 3+} and minor Fe{sup 2+} ions in a magnetically ordered state and participating in a “fast” electronic exchange.

  3. A novel Fe–Cr–Nb matrix composite containing the TiB_2 neutron absorber synthesized by mechanical alloying and final hot isostatic pressing (HIP) in the Ti-tubing

    International Nuclear Information System (INIS)

    Litwa, Przemysław; Perkowski, Krzysztof; Zasada, Dariusz; Kobus, Izabela; Konopka, Gustaw; Czujko, Tomasz; Varin, Robert A.

    2016-01-01

    The Fe–Cr–Ti-Nb elemental powders were mechanically alloyed/ball milled with TiB_2 and a small quantity of Y_2O_3 ceramic to synthesize a novel Fe-based alloy-ceramic powder composite that could be processed by hot isostatic pressing (HIP) for a perceived potential application as a neutron absorber in nuclear reactors. After ball milling for the 30–80 h duration relatively uniform powders with micrometric sizes were produced. With increasing milling time a fraction of TiB_2 particles became covered with the much softer Fe-based alloy which resulted in the formation of a characteristic “core-mantel” structure. For the final HIP-ing process the mechanically alloyed powders were initially uniaxially pressed into rod-shaped compacts and then cold isostatically pressed (CIP-ed). Subsequently, the rod-shaped compacts were placed in the Ti-tubing and subjected to hot isostatic pressing (HIP) at 1150 °C/200 MPa pressure. The HIP-ing process resulted in the formation of the near-Ti and intermediate diffusional layers in the microstructure of HIP-ed samples which formed in accord with the Fe-Ti binary phase diagram. Those layers contain the phases such as α-Ti (HCP), the FeTi intermetallic and their hypo-eutectoid mixtures. In addition, needle-like particles were formed in both layers in accord with the Ti-B binary phase diagram. Nanohardness testing, using a Berkovich type diamond tip, shows that the nanohardness in the intermediate layer areas, corresponding to the composition of the hypo-eutectoid mixture of Ti-FeTi, equals 980.0 (±27.1) HV and correspondingly 1176.9 (±47.6) HV for the FeTi phase. The nanohardness in the sample's center in the areas with the fine mixture of Fe-based alloy and small TiB_2 particles equals 1048.3 (±201.8) HV. The average microhardness of samples HIP-ed from powders milled for 30 and 80 h is 588 HV and 733 HV, respectively. - Highlights: • A Fe–Cr–Nb-based composite with TiB_2 neutron absorbing ceramic was mechanically

  4. Lattice Thermal Conductivity from Atomistic Simulations: ZrB2 and HfB2

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  5. Magnetic properties improvement of melt spun Co{sub 86.5}Hf{sub 11.5}B{sub 2} nanocomposites by refractory elements substitution

    Energy Technology Data Exchange (ETDEWEB)

    Chang, H.W. [Department of Applied Physics, Tunghai University, Taichung 407, Taiwan (China); Lin, Y.H.; Shih, C.W.; Liao, M.C.; Lee, Y.I. [Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Chang, W.C., E-mail: phywcc@ccu.edu.tw [Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Yang, C.C. [Department of Physics, Chung-Yuan Christian University, Chungli 320, Taiwan (China); Shaw, C.C. [Superrite Electronics Co. Ltd., Taipei 111, Taiwan (China)

    2016-03-01

    Magnetic properties of melt spun Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons with refractory elements substitution (M=Cr, Nb, Ti, Zr) have been studied. For ternary Co{sub 86.5}Hf{sub 11.5}B{sub 2} ribbon, permanent magnetic properties of B{sub r}=0.71 T, {sub i}H{sub c}=192 kA/m, and (BH){sub max}=34.4 kJ/m{sup 3} are obtained, and they are significantly improved to B{sub r}=0.73–0.76 T, {sub i}H{sub c}=136–216 kA/m and (BH){sub max}=38.4–52.8 kJ/m{sup 3} with M substitution. Summarized with the results of x-ray diffraction refinement, thermal magnetic analysis, and transmission electron microscopy, the Co{sub 86.5}Hf{sub 10.5}MB{sub 2} nanocomposites following the optimal crystallization treatment mainly consist of orthorhombic 7:1 and face-center-cubic Co phases. Fine microstructure with average grain size in the range of 12.5−19.6 nm promotes exchange coupling effect between magnetic grains, thus improving permanent magnetic properties. The magnetic field dependence of coercivity reveals that coercivity of the studied Co{sub 86.5}Hf{sub 10.5}MB{sub 2} nonocomposites is mainly governed by the reverse domain nucleation mechanism. - Highlights: • M substitution refines the grain size. • M substitution strengthens the exchange coupling effect between grains. • M substitution improves hard magnetic properties of Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons. • The coercivity is mainly governed by the reverse domain nucleation mechanism. • Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons are relevant candidate for RE free permanent magnets.

  6. Feasibility study of electrophoresis deposition of DyF3 on Nd-Fe-B particles for coercivity enhancement

    Directory of Open Access Journals (Sweden)

    K. M. Kim

    2018-05-01

    Full Text Available Feasibility of the electrophoresis deposition (EPD technique for homogeneous and adhesive deposition of DyF3 particles on the Nd-Fe-B-type particles was studied, and coercivity enhancement in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD was investigated. HDDR-treated Nd12.5Fe80.6B6.4Ga0.3Nb0.2 particles were deposited with DyF3 particles by EPD. More homogeneous and adhesive deposition of DyF3 particles on the surface of Nd-Fe-B particles was made by the EPD with respect to conventional dip-coating, and this led to more active and homogeneous diffusion of Dy. More profound coercivity enhancement was achieved in the diffusion-treated Nd-Fe-B-type particles deposited with DyF3 by EPD compared to dip-coated particles.

  7. Stress and annealing induced changes in the Curie temperature of amorphous and nanocrystalline FeZr and FeNb based alloys

    International Nuclear Information System (INIS)

    Gorria, P.; Orue, I.; Fernandez-Gubieda, M.L.; Plazaola, F.; Zabala, N.; Barandiaran, J.M.

    1996-01-01

    The stress and annealing dependence of the Curie temperature in FeZrBCu alloys is presented. A change of about 50 /GPa has been observed. The change in amorphous matrix composition upon crystallization produces an expected increase in T C (about 200 C) which is similar to the experimentally observed increase. This behaviour is opposite to that observed in Fe-Nb based alloys. (orig.)

  8. Evaluación de algunos métodos para la extracción de los micronutrimentos B, Fe, Zn, Mn y Cu en suelos de las zonas norte y centro del Valle del Cauca

    Directory of Open Access Journals (Sweden)

    García O. Álvaro

    1988-12-01

    Full Text Available Para evaluar el contenido de Fe, Cu, Mn y Zn disponibles en el suelo se usaron: EDTA 0.01M + NaHCD3 0.5 N, HCI 0.05 N + H2SD4, DTPA y HCI 0.1N. El B disponible fue extraído con Ca(H2PD42H20 0.008 M, HCI 0.05N y NH40Ac pH 4.8. Para la determinación de los micronutrimentos en el material vegetal se usaron como soluciones para la digestión el metanol ácido y la mezcla nítrico perclórica para Fe, Mn, Cu y Zn; para el B se usó el método de Hunter. El DTP A resultó adecuado para evaluar Fe y Cu, el doble ácido para Mn, el NaHC03 + EDTA para el Zn y el HCI 0.05N y Ca (H2P042 H20 para evaluar el B disponible en el suelo. La mezcla nítrico perclórica resultó más apropiada para la determinación de los nutrimentos en los tejidos que el metanol ácido.To evaluate available Fe, Cu, Mn and Zn was used: EDTA 00.1M + NaHC03 0.5N, HCI 0.05N + H2S04 0.025N, DTPA and HCI 0.1 N. Available B was extracted with Ca (H2P042 H2O 0.008M; HCI 0.05N and NH40Ac pH 4.8. For determination of micronutriment in the vegetal material was used as solution acid methanol and nitric – perchloric mixture for Fe, Mn, Cu and Zn; for B Hunters methods. DTPA is advantageous to evaluate Fe and Cu, double acid to Mn, NaHC03 + EDTA to Zn and HCI 0.05N and Ca(H2P042 H20 to evaluate B available in the soil. Nitric-perchloric mixture is most advantageous for determination of nutriments in the tissues than acid methanol.

  9. Elastic properties of amorphous T0.75Y0.75B14 (T   =  Sc, Ti, V, Y, Zr, Nb) and the effect of O incorporation on bonding, density and elasticity (T ′  =  Ti, Zr)

    International Nuclear Information System (INIS)

    Hunold, Oliver; Keuter, Philipp; Bliem, Pascal; Music, Denis; Wittmers, Friederike; Ravensburg, Anna L; Schneider, Jochen M; Primetzhofer, Daniel

    2017-01-01

    We have systematically studied the effect of transition metal valence electron concentration (VEC) of amorphous T 0.75 Y 0.75 B 14 (a- T 0.75 Y 0.75 B 14 , T   =  Sc, Ti, V, Y, Zr, Nb) on the elastic properties, bonding, density and electronic structure using ab initio molecular dynamics. As the transition metal VEC is increased in both periods, the bulk modulus increases linearly with molar- and mass density. This trend can be understood by a concomitant decrease in cohesive energy. T ′  =  Ti and Zr were selected to validate the predicted data experimentally. A-Ti 0.74 Y 0.80 B 14 and a-Zr 0.75 Y 0.75 B 14 thin films were synthesized by high power pulsed magnetron sputtering. Chemical composition analysis revealed the presence of up to 5 at.% impurities, with O being the largest fraction. The measured Young’s modulus values for a-Ti 0.74 Y 0.80 B 14 (301  ±  8 GPa) and a-Zr 0.75 Y 0.75 B 14 (306  ±  9 GPa) are more than 20% smaller than the predicted ones. The influence of O incorporation on the elastic properties for these selected systems was theoretically studied, exemplarily in a-Ti 0.75 Y 0.75 B 12.75 O 1.25 . Based on ab initio data, we suggest that a-Ti 0.75 Y 0.75 B 14 exhibits a very dense B network, which is partly severed in a-Ti 0.75 Y 0.75 B 12.75 O 1.25 . Upon O incorporation, the average coordination number of B and the molar density decrease by 9% and 8%, respectively. Based on these data the more than 20% reduced Young’s modulus obtained experimentally for films containing impurities compared to the calculated Young’s modulus for a-Ti 0.75 Y 0.75 B 14 (without incorporated oxygen) can be rationalized. The presence of oxygen impurities disrupts the strong B network causing a concomitant decrease in molar density and Young’s modulus. Very good agreement between the measured and calculated Young’s modulus values is obtained if the presence of impurities is considered in the calculations. The

  10. Development of Fe/Nb-based solar photocatalysts for water treatment: impact of different synthesis routes on materials properties.

    Science.gov (United States)

    Ribeiro, Marília C M; Amorim, Camila C; Moreira, Regina F P M; Oliveira, Luiz C A; Henriques, Andréia B; Leão, Mônica M D

    2018-04-27

    Semiconductors based on Fe/Nb oxides can present both solar sensitivity and high catalytic activity. However, there is still a lack regarding the comparison between different routes to produce Fe/Nb-based solar photocatalysts and the evaluation of the impact of the synthesis operating conditions on the material properties. In this work, Fe/Nb 2 O 5 ratio, type of precipitating agent, presence/absence of washing stage, and temperature of calcination were verified to be the most relevant parameters in the synthesis by the co-precipitation method. These factors led to remarkable differences in the properties and performance of the photocatalysts produced by each distinct synthesis route. Composition, iron species present in the materials, crystallinity characteristics, and pH of the catalysts were affected, leading to different photocatalytic activities under UV-Vis light. Due to their characteristics, the synthesized materials are potential photocatalysts for application in solar processes. Graphical abstract ᅟ.

  11. Internal friction of Fe-B alloys neutron irradiated at low temperature

    International Nuclear Information System (INIS)

    Kitajima, Kazunori; Futagami, Koji; Abe, Hironobu; Yoshida, Hiroyuki.

    1975-01-01

    Measurements were made on the internal friction of Fe-B alloys irradiated by neutron at 16 0 K to the dose of 3x10 16 nvt (>1 MeV) and 6x10 17 nvt (thermal). Boron was used to enhance the production of defects by the nuclear transformation B 10 (n,α)Li 7 . Relaxation peaks were found in specimens containing dispersed fine precipitates of NbB 2 in range of B 500--7200 wt ppm and Nb 2000--30000 wt ppm. The most prominent peak is the one with the peak temperature of 169 0 K at the frequency of 264 c/sec. Activation energy determined from the peak shift is 0.28+-0.01 eV, which is nearly equal to that of migration of self-interstitial reported on pure iron. However activation energy of the decay of peaks by annealing is about 0.7 eV. Interpretation was presented that the peak may be attributed to re-orientation of self-interstitials loosely bound to a boron atom. (auth.)

  12. Diatomic substitutionals in superconducting Nb(1-x)B2

    International Nuclear Information System (INIS)

    Farrell, H.H.; LaViolette, Randall A.; Lillo, T.M.

    2006-01-01

    Using first-principles, density functional theory calculations, we have shown that the increase in superconducting critical temperature to above 9 K experimentally observed for B-rich, off-stoichiometry NbB 2 material is associated with the formation of B-dimers on Nb sites rather than with the formation of Nb vacancies, as previously proposed. Our calculations show that certain of these B-dimer configurations have lower binding energies than do the vacancy structures. This result is pressure independent in the range between 0 and 10 GPa, and above. Further, the dimer-containing materials have a higher electronic density of states at the Fermi level than do the vacancy structures. Finally, the presence of B-dimers results in the splitting off of phonon normal modes. These last two factors are relevant to the improved superconducting properties

  13. Correlation between zirconium oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

    International Nuclear Information System (INIS)

    Park, Sang Yoon; Lee, Myung Ho; Choi, Byoung Kwon; Jeong, Yong Hwan; Jung, Youn Ho

    2001-01-01

    To evaluate the correlation of Zr oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys, the corrosion behavior of the alloys was tested in the autoclave containing 70 ppm LiOH solution at 360 .deg. C. The characteristics of the oxide on the alloys were investigated by using the electrochemical impedance spectrosocpy (EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of Nb. The equivalent circuit of the oxide was composed on the base of the spectrum from EIS measurements on the oxide layers that had formed at pre-and post-transition regions on the curve of corrosion rate. By using the capacitance characteristics of the equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results

  14. Correlation between the oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

    Science.gov (United States)

    Park, Sang-Yoon; Lee, Myung-Ho; Jeong, Yong-Hwan; Jung, Youn-Ho

    2004-12-01

    The correlation between the oxide impedance and corrosion behavior of two series of Zr-Nb-Sn-Fe-Cu alloys was evaluated. Corrosion tests were performed in a 70 ppm LiOH aqueous solution at 360°C for 300 days. The results of the corrosion tests revealed that the corrosion behavior of the alloys depended on the Nb and Sn content. The impedance characteristics for the pre- and post-transition oxide layers formed on the surface of the alloys were investigated in sulfuric acid at room temperature. From the results, a pertinent equivalent circuit model was preferably established, explaining the properties of double oxide layers. The impedance of the oxide layers correlated with the corrosion behavior; better corrosion resistance always showed higher electric resistance for the inner layers. It is thus concluded that a pertinent equivalent circuit model would be useful for evaluating the long-term corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys.

  15. Three-peak behavior in giant magnetoimpedance effect in Fe73.5-x Cr x Nb3Cu1Si13.5B9 amorphous ribbons

    International Nuclear Information System (INIS)

    Rosales-Rivera, A.; Valencia, V.H.; Pineda-Gomez, P.

    2007-01-01

    A systematic study of the giant magnetoimpedance (GMI) effect in Fe 73.5- x Cr x Nb 3 Cu 1 Si 13.5 B 9 amorphous ribbons with x=0, 2, 4, 6, 8 and 10 is presented. The complex impedance in these compounds was measured for applied fields from -80 to 80 Oe at room temperature, via the so-called four-probe technique. Depending on the frequency, the experimentally observed GMI curves usually exhibit two types of behavior, namely single-peak (SP), and two-peak (TP). In this work, we emphasize the presence of a 'three-peak behavior' in GMI curves. It occurs between SP and TP behaviors. The mechanisms leading to the three-peak behavior are discussed

  16. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-01-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

  17. High pressure die casting of Fe-based metallic glass.

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-11

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  18. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  19. Ferromagnetic resonance on oxideless magnetic Fe and FeRh nanoparticles; Ferromagnetische Resonanz an oxidfreien magnetischen Fe und FeRh Nanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Trunova, Anastasia

    2009-05-25

    This work is dedicated to investigations of structural and magnetic properties of the colloidal Fe/Fe{sub x}O{sub y} nanocubes (13 nm) and the Fe{sub x}Rh{sub 100-x} core/shell nanoparticles (2 nm). As compared with other works, where the measurements on oxidized nanoparticles were carried out, we additionally performed investigations on nanoparticles in an oxide free state. In order to make the measurements on oxide free particles possible, oxygen- and hydrogenplasma was used to remove the ligands and reduce the oxide shell of the Fe nanocubes. The oxide free Fe nanocubes were covered with a Ag/Pt protective coating to prevent them from new oxidation. This method allowed carrying out the magnetic measurements on oxide free Fe nanocubes. Micromagnetic simulations as well as simulations of the high frequency susceptibility were used for the data analysing. It was found that both the g-factor g=2.09{+-}0.01 and the anisotropy constant K{sub 4}=(4.8{+-}0.5).10{sup 4} J/m{sup 3} coincide with that of bulk iron. However, the saturation magnetization M{sub S}(5 K)=(1.2{+-}0.12).10{sup 6} A/m differs from the bulk value by 30%. The reduction by 30% compared to the bulk value in the case of nanoparticles may be caused by the following possible reasons: a) the presence of inner oxide layer (approx. 10 at.%) that cannot be reduced; b) the anti-parallel order between magnetic moments of iron core and magnetic moments of antiferomagnetic iron oxide; c) some structural changes of the surface after plasma treatment. The obtained damping parameter {alpha}=0.03{+-}0.005 is ten times larger than that of the Fe layers as it is known for nanoparticles systems in general. The core/shell Fe{sub x}Rh{sub 100-x} nanoparticles (x=80,50) were produced under Ar-atmosphere and were sealed into a quartz tube to prevent oxidation. The analysis of g-factors shows that the value for the FePh nanoparticles with Fe-rich core is larger (g=2.08{+-}0.01) than that for the nanoparticles with Rh

  20. Zr-Sn-Nb alloys. Preliminary studies

    International Nuclear Information System (INIS)

    Danon, C.A.; Arias, D.E.

    1993-01-01

    Studies of the Zr-Sn-Nb diagram have been started, focussing on the Zr-rich corner, near the composition of Zirlo commercial alloy, Zr-1Sn-1Nb, and with Fe and O contents usual in nuclear grade materials. Three alloys were melted, namely Zr-4Sn-2.4Nb (A), Zr-1Sn-3Nb (B) and Zr-2.1Sn-1Nb (C). α/β transformation temperatures were measured through the variation of electrical resistivity(p) vs temperature (T). Values of 560 deg C, 670 deg C and 750 deg C were measured for the α→α+β reaction and 980 deg C, 910 deg C and 1000 deg C for the α+β→β reaction, for the A, B and C alloys, respectively in that order. Some samples were submitted to heat treatments (62 and 216 hours at 825 deg C, 120 hours at 875 deg C). Optical and scanning electronic microscopy of those samples confirmed our resistivity results. (Author)

  1. Magnetoimpedance of stress and/or field annealed Fe73.5Cu1Nb3Si15.5B7 amorphous and nanocrystalline ribbon

    International Nuclear Information System (INIS)

    Miguel, C.; Zhukov, A.P.; Gonzalez, J.

    2003-01-01

    Magnetoimpedance (MI) response of as-cast and annealed Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 amorphous alloy ribbon has been investigated. The thermal treatments were performed by current annealing technique (density 45 A/mm 2 during 1-120 min) under the action of a tensile stress of 500 MPa and/or an axial magnetic field of 750 A/m. For short annealing time (less than 5 min), the three kinds of treatment induced an uniaxial magnetic anisotropy in the amorphous state with a maximum of MI of 15%, while for long annealing the nanocrystallization process occurs with larger MI effect of around 22%. This MI behaviour is explained taking into account the role of the induced magnetic anisotropy and the microstructural changes owing to the thermal treatments

  2. The hyperfine fields at 181Ta in HfFe2

    International Nuclear Information System (INIS)

    Cekic, B.; Ivanovic, N.; Manasijevic, M.; Koicki, S.; Koteski, V.; Cavor, J.; Radisavljevic, I.; Milosevic, Z.; Novakovic, N.

    2001-01-01

    The hyperfine fields (HFF) in the polycrystalline HfFe 2 binary compound consisting the two various phases MgCu 2 and MgZn 2 , were measured at 181 Ta probe ion sites by gamma-gamma time differential perturbed angular correlations (TDPAC) technique in a wide temperature range. The origin of the hyperfine magnetic field is discussed taking in account the coordination of the 181 Ta probe ion, its core polarization and the polarization of conduction electrons around the 181 Ta site in both phases. (author)

  3. A first-principles study of cementite (Fe{sub 3}C) and its alloyed counterparts: Elastic constants, elastic anisotropies, and isotropic elastic moduli

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, G., E-mail: g-ghosh@northwestern.edu [Department of Materials Science and Engineering, Robert R. McCormick School of Engineering and Applied Science, Northwestern University, 2220 Campus Drive, Evanston, IL 60208-3108 (United States)

    2015-08-15

    A comprehensive computational study of elastic properties of cementite (Fe{sub 3}C) and its alloyed counterparts (M{sub 3}C (M = Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Si, Ta, Ti, V, W, Zr, Cr{sub 2}FeC and CrFe{sub 2}C) having the crystal structure of Fe{sub 3}C is carried out employing electronic density-functional theory (DFT), all-electron PAW pseudopotentials and the generalized gradient approximation for the exchange-correlation energy (GGA). Specifically, as a part of our systematic study of cohesive properties of solids and in the spirit of materials genome, following properties are calculated: (i) single-crystal elastic constants, C{sub ij}, of above M{sub 3}Cs; (ii) anisotropies of bulk, Young’s and shear moduli, and Poisson’s ratio based on calculated C{sub ij}s, demonstrating their extreme anisotropies; (iii) isotropic (polycrystalline) elastic moduli (bulk, shear, Young’s moduli and Poisson’s ratio) of M{sub 3}Cs by homogenization of calculated C{sub ij}s; and (iv) acoustic Debye temperature, θ{sub D}, of M{sub 3}Cs based on calculated C{sub ij}s. We provide a critical appraisal of available data of polycrystalline elastic properties of alloyed cementite. Calculated single crystal properties may be incorporated in anisotropic constitutive models to develop and test microstructure-processing-property-performance links in multi-phase materials where cementite is a constituent phase.

  4. Effect of Nb on glass forming ability and plasticity of (Ti-Cu)-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Suo, Z.Y.; Qiu, K.Q.; Li, Q.F.; Ren, Y.L.; Hu, Z.Q.

    2010-01-01

    A Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 alloy. The glass forming ability Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promote the glass forming ability. Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG compared to 0.15% for Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti-Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.

  5. Ternary oxide nanostructures and methods of making same

    Science.gov (United States)

    Wong, Stanislaus S [Stony Brook, NY; Park, Tae-Jin [Port Jefferson, NY

    2009-09-08

    A single crystalline ternary nanostructure having the formula A.sub.xB.sub.yO.sub.z, wherein x ranges from 0.25 to 24, and y ranges from 1.5 to 40, and wherein A and B are independently selected from the group consisting of Ag, Al, As, Au, B, Ba, Br, Ca, Cd, Ce, Cl, Cm, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Ho, I, In, Ir, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Rb, Re, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Tc, Te, Ti, Tl, Tm, U, V, W, Y, Yb, and Zn, wherein the nanostructure is at least 95% free of defects and/or dislocations.

  6. On the frequency dependence of the magnetic permeability of FeHfO thin films

    NARCIS (Netherlands)

    Bloemen, P.J.H.; Rulkens, B.

    1998-01-01

    The frequency dependence of the magnetic permeability as well as of the electrical impedance have been investigated for soft-magnetic granular FeHfO thin films. The impedance measurements indicate that capacitive effects resulting from the inhomogeneous structure of the layers are of no importance

  7. TEM study on a new Zr-(Fe, Cu) phase in furnace-cooled Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cu alloy

    Science.gov (United States)

    Liu, Yushun; Qiu, Risheng; Luan, Baifeng; Hao, Longlong; Tan, Xinu; Tao, Boran; Zhao, Yifan; Li, Feitao; Liu, Qing

    2018-06-01

    A new Zr-(Fe, Cu) phase was found in furnace-cooled Zr-1.0Sn-0.3Nb-0.3Fe- 0.1Cu alloy and alloys aged at 580 °C for 10min, 2 h and 10 h. Electron diffraction experiment shows the crystal structure of this phase to be body-centered tetragonal with unit cell dimensions determined to be a = b = 6.49 Å, c = 5.37 Å. Its possible space groups have been discussed and the reason accounting for its formation is believed to be the addition of Cu according to the atom-level images. In addition, no crystal structural or chemical composition changes were observed throughout the aging process.

  8. Efecto del BiFeO3 en las propiedades del sistema ferroeléctrico libre de plomo K0.5Na0.5NbO3

    Directory of Open Access Journals (Sweden)

    Pinza, Billy N.

    2014-10-01

    Full Text Available In order to obtain a multiferroic material, powders and ceramic pieces, of the lead-free ferroelectric (1-x-x K0.5Na0.5NbO3 (Bi0.8La0.2FeO3 (KNN-BLFO (x = 0.005, 0.010, 0.015, 0.020, 0.025 system were prepared using the combustion reaction method. For all the studied perovskite phase, stoichiometries feature KNN was obtained. Using characterisation techniques, it was determined that the BLFO is incorporated in the crystal structure of KNN without modifying present a phase transition. Moreover, It was also proved that the addition of the BLFO to KNN, alters the particle size of the obtained powders and generates magnetic behavior in this ferroelectric.En la búsqueda de un material multiferroico, se prepararon polvos y piezas cerámicas del sistema ferroeléctrico libre de plomo (1-xK0.5Na0.5NbO3-x(Bi0.8La0.2FeO3 (KNN-BLFO (x=0.005, 0.010, 0.015, 0.020, 0.025, mediante el método de reacción por combustión. Para todas las estequiometrias estudiadas se obtuvo la fase perovskita característica del KNN. Con las diferentes caracterizaciones se determinó que el BLFO se incorpora en la estructura cristalina del KNN modificándola sin que se presente una transición de fase. Se comprobó además que la adición del BLFO al KNN, altera el tamaño de partícula de los polvos obtenidos y genera comportamiento magnético en este ferroeléctrico.

  9. Adhesive and Cohesive Strength in FeB/Fe2B Systems

    Science.gov (United States)

    Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

    2018-05-01

    In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

  10. Semiquantitative spectrographic analysis of nuclear interest minerals and of various products

    International Nuclear Information System (INIS)

    Alvarez Gonzalez, F.; Roca Adell, M.; Fernandez Cellini, R.

    1958-01-01

    Because the great number of samples of various kinds receiving in the Chemical Division, minerals in the most part, for its complete analysis, a rapid spectrographic method has been developed. It permits the determination of the following elements with a semiquantitative character. Al, As, Ag, Au, B, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, Hf, Hn, In, K, La, Li, Mg, Mn, Mo, Na, Nb, P, Pb, Pt, Sb, Si, Sn, Sr, Ta, Ti, V, W, Y, Zn and Zr. (Author) 14 refs

  11. TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel with Hf addition

    International Nuclear Information System (INIS)

    Dou, Peng; Kimura, Akihiko; Kasada, Ryuta; Okuda, Takanari; Inoue, Masaki; Ukai, Shigeharu; Ohnuki, Somei; Fujisawa, Toshiharu; Abe, Fujio; Jiang, Shan; Yang, Zhigang

    2017-01-01

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) ferritic steel with Hf addition, i.e., SOC-16 (Fe-15Cr-2W-0.1Ti-4Al-0.62Hf-0.35Y 2 O 3 ), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr ODS ferritic steel without Hf addition, i.e., SOC-9 (Fe-15.5Cr-2W-0.1Ti-4Al-0.35Y 2 O 3 ), the dispersion morphology and coherency of the oxide nanoparticles in SOC-16 were significantly improved. Almost all the small nanoparticles (diameter <10 nm) in SOC-16 were found to be consistent with cubic Y 2 Hf 2 O 7 oxides with the anion-deficient fluorite structure and coherent with the bcc steel matrix. The larger particles (diameter >10 nm) were also mainly identified as cubic Y 2 Hf 2 O 7 oxides with the anion-deficient fluorite structure. The results presented here are compared with those of SOC-9 with a brief discussion of the underlying mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the superior strength, excellent irradiation tolerance and extraordinary corrosion resistance of SOC-16.

  12. Effect of heat treatment on the electrochemical behaviour and catalytic activity of metal-glass of an Fe76.1Cu1.0Nb3.0Si13.8B6.1

    International Nuclear Information System (INIS)

    Zhdanova, L.I.; Sharipova, E.Kh.; Lad'yanov, V.I.; Volkov, V.A.

    1999-01-01

    Effect of the different degree of the initial surface crystallization of Fe 76.1 Cu 1.0 Nb 3.0 Si 13.8 B 6.1 metal glasses on the electrochemical behaviour and catalytic activity of the alloy during thermal treatment of tapes was studied. Growth of amorphous-nanocrystalline structure during annealing is shown to improve protective properties of fast-hardened tapes. The highest corrosion resistance of the material is manifested when in nanocrystalline state subsequent to annealing under 550 deg C [ru

  13. Role of Nb content in nanocrystals

    International Nuclear Information System (INIS)

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

    1995-01-01

    The influence of Nb content on the formation of nanocrystalline phase in the Fe 73.5-x Cu 1 Nb 3+x Si 13.5 B 9 system was studied by Moessbauer spectroscopy. The kinetics of crystallization was observed by isothermal heating at temperature 550 C during annealing time up to 16 h. The samples containing 3 and 4.5 at% were compared. Nanocrystalline phase formation was explained on the basis of cluster model. ((orig.))

  14. Distribution of impurity states and charge transport in Zr{sub 0.25}Hf{sub 0.75}Ni{sub 1+x}Sn{sub 1−y}Sb{sub y} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuanfeng; Makongo, Julien P.A. [Laboratory for Emerging Energy and Electronic Materials, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Page, Alexander [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Sahoo, Pranati [Laboratory for Emerging Energy and Electronic Materials, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Uher, Ctirad [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Stokes, Kevin [The Advanced Materials Research Institute, Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States); Poudeu, Pierre F.P., E-mail: ppoudeup@umich.edu [Laboratory for Emerging Energy and Electronic Materials, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-02-15

    Energy filtering of charge carriers in a semiconducting matrix using atomically coherent nanostructures can lead to a significant improvement of the thermoelectric figure of merit of the resulting composite. In this work, several half-Heusler/full-Heusler (HH/FH) nanocomposites with general compositions Zr{sub 0.25}Hf{sub 0.75}Ni{sub 1+x}Sn{sub 1−y}Sb{sub y} (0≤x≤0.15 and y=0.005, 0.01 and 0.025) were synthesized in order to investigate the behavior of extrinsic carriers at the HH/FH interfaces. Electronic transport data showed that energy filtering of carriers at the HH/FH interfaces in Zr{sub 0.25}Hf{sub 0.75}Ni{sub 1+x}Sn{sub 1−y}Sb{sub y} samples strongly depends on the doping level (y value) as well as the energy levels occupied by impurity states in the samples. For example, it was found that carrier filtering at HH/FH interfaces is negligible in Zr{sub 0.25}Hf{sub 0.75}Ni{sub 1+x}Sn{sub 1−y}Sb{sub y} (y=0.01 and 0.025) composites where donor states originating from Sb dopant dominate electronic conduction. However, we observed a drastic decrease in the effective carrier density upon introduction of HH/FH interfaces for the mechanically alloyed Zr{sub 0.25}Hf{sub 0.75}Ni{sub 1+x}Sn{sub 0.995}Sb{sub 0.005} samples where donor states from unintentional Fe impurities contribute the largest fraction of conduction electrons. This work demonstrates the ability to synergistically integrate the concepts of doping and energy filtering through nanostructuring for the optimization of electronic transport in semiconductors. - Graphical abstract: Electronic transport in semiconducting half-Heusler (HH) matrices containing full-Heusler (FH) nanoinclusions strongly depends on the energy distribution of impurity states within the HH matrix with respect to the magnitude of the potential energy barrier at the HH/FH interfaces. - Highlights: • Coherent nanostructures enhanced thermoelectric behavior of half-Heusler alloys. • Nanostructures act as energy filter of

  15. Structural and magnetic behavior of the cubic oxyfluoride SrFeO{sub 2}F studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Corey M., E-mail: thompco@mcmaster.ca [Department of Chemistry, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Brockhouse Institute of Materials Research, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Blakely, Colin K. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Flacau, Roxana [Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratories, Chalk River, ON, Canada K0J 1J0 (Canada); Greedan, John E. [Department of Chemistry, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Brockhouse Institute of Materials Research, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Poltavets, Viktor V. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)

    2014-11-15

    The oxyfluoride SrFeO{sub 2}F has been prepared via a low temperature route involving the infinite-layer SrFeO{sub 2} and XeF{sub 2}. SrFeO{sub 2}F crystallizes in the cubic space group Pm-3m with disordered oxygen and fluorine atoms on the anion site. Recent reports demonstrated that SrFeO{sub 2}F is antiferromagnetic at room temperature and the zero field cooled and field cooled curves diverge at ∼150 K and ∼60 K, suggesting that the material has a spin glassy magnetic state at low temperatures. In this article, variable-temperature neutron diffraction (4–723 K) was performed to clarify the magnetic behavior observed in this material. Neutron powder diffraction measurements confirmed the antiferromagnetic (AFM) ordering of the system at room temperature. Below 710(1) K, the magnetic structure is a G-type AFM structure characterized by a propagation vector k=(1/2 , 1/2 , 1/2 ). The ordered moments on Fe{sup 3+} are 4.35(6)µ{sub B} at 4 K and 4.04(5)µ{sub B} at 290 K. Our results indicate that the cubic structure is retained all the way to base temperature (4 K) in contrast to PbFeO{sub 2}F. These results are compared with those of Pb and Ba analogs which exhibit very similar magnetic behavior. Furthermore, the observation of magnetic reflections at 4 K in the diffraction pattern shows the absence of the previously proposed spin glassy behavior at low temperatures. Previous proposals to explain the ZFC/FC divergences are examined. - Graphical abstract: Variable temperature powder neutron diffraction was employed to follow the evolution of the long range antiferromagnetic state in SrFeO{sub 2}F. - Highlights: • SrFeO{sub 2}F prepared via low temperature route involving SrFeO{sub 2} and XeF{sub 2}. • The cubic structure, Pm-3m, is retained at low temperatures, 4 K. • The magnetic structure is G-type AFM with T{sub N}=710 K and Fe{sup 3+} moment of 4.35µ{sub B}. • A small volume, bulk decoupled, spin glassy domain/cluster mechanism is proposed.

  16. Effect of magnetic soft phase on the magnetic properties of bulk anisotropic Nd2Fe14B/α-Fe nanocomposite permanent magnets

    Science.gov (United States)

    Li, Yuqing; Yue, Ming; Zhao, Guoping; Zhang, Hongguo

    2018-01-01

    The effects of soft phase with different particle sizes and distributions on the Nd2Fe14B/α-Fe nanocomposite magnets have been studied by the micro-magnetism simulation. The calculated results show that smaller and/or scattered distribution of soft phase can benefit to the coercivity (H ci) of the nanocomposite magnets. The magnetization moment evolution during magnetic reversal is systematically analyzed. On the other hand, magnetic properties of anisotropic Nd-Fe-B/α-Fe nanocomposite magnets prepared by hot pressing and hot deformation methods also provide evidences for the calculated results.

  17. Irradiation effects on Fe distributions in zircaloy-2 and Zr-2.5Nb

    International Nuclear Information System (INIS)

    Zou, H.; Hood, G.M.; Roy, J.A.

    1995-03-01

    Irradiation of large-grained Zr-2.5Nb (ZN) and Zircaloy-2 (Zy) with 1.5 MeV Ar ions to a fluence of ∼ 10 20 /m 2 (≡ 10 dpa) at 50, 300 and 420 deg C leads to enhanced α-phase Fe levels of 250-1500 ppma, compared to equivalent non-irradiated state values of ∼ 70 ppma. In ZN the β-phase Fe levels fell from about 6000 to 3500 ppma: this result accords, qualitatively, with the loss of Fe from the β-phase following in-service neutron irradiation. Measurements on Zy showed that the Fe concentrations were higher near the specimen surfaces. Limited data for Ni distributions in Zy show similar (to Fe) behaviour. (author). 18 refs., 2 tabs

  18. Laser-induced damage thresholds of bulk and coating optical materials at 1030  nm, 500  fs.

    Science.gov (United States)

    Gallais, Laurent; Commandré, Mireille

    2014-02-01

    We report on extensive femtosecond laser damage threshold measurements of optical materials in both bulk and thin-film form. This study, which is based on published and new data, involved simple oxide and fluoride films, composite films made from a mixture of two dielectric materials, metallic films, and the surfaces of various bulk materials: oxides, fluorides, semiconductors, and ionic crystals. The samples were tested in comparable conditions at 1030 nm, 375 to 600 fs, under single-pulse irradiation. A large number of different samples prepared by different deposition techniques have been tested, involving classical materials used in the fabrication of optical thin film components (Ag, AlF3, Al2O3, HfO2, MgF2, Nb2O5, Pt, Sc2O3, SiO2, Ta2O5, Y2O3, and ZrO2) and their combination with codeposition processes. Their behaviors are compared with the surfaces of bulk materials (Al2O3, BaF2, CaF2, Ge, KBr, LiF, MgF2, NaCl, Quartz, Si, ZnS, ZnSe, and different silica glasses). Tabulated values of results are presented and discussed.

  19. Controlling the crystallization and magnetic properties of melt-spun Pr2Fe14B/α-Fe nanocomposites by Joule heating

    Science.gov (United States)

    Jin, Z. Q.; Cui, B. Z.; Liu, J. P.; Ding, Y.; Wang, Z. L.; Thadhani, N. N.

    2004-05-01

    Pr2Fe14B/α-Fe based nanocomposites have been prepared through crystallization of melt-spun amorphous Pr7Tb1Fe85Nb0.5Zr0.5B6 ribbons by means of ac Joule heating while simultaneously monitoring room-temperature electrical resistance R. The R value shows a strong variation with respect to applied current I, and is closely related to the amorphous-to-nanocrystalline phase transformation. The curve of R versus I allows one to control the crystallization behavior during Joule heating and to identify the heat-treatment conditions for optimum magnetic properties. A coercivity of 550 kA/m and a maximum energy product of 128 kJ/m3 have been obtained upon heating the amorphous ribbons at a current of 2.0 A. These properties are around 30% higher than the values of samples prepared by conventionally (furnace) annealed amorphous ribbons.

  20. Structure and tensile properties of Fe-Cr model alloy strengthened by nano-scale NbC particles derived from controlled crystallization of Nb-rich clusters

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Lei [College of Materials and Chemical Engineering, Three Gorges University, Yichang 443002 (China); Guo, Qianying [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China); Liu, Yongchang, E-mail: licmtju@163.com [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China); Yu, Liming; Li, Huijun [State Key Lab of Hydraulic Engineering Simulation and Safety, School of Material Science and Engineering, Tianjin University, Tianjin 300354 (China)

    2016-09-30

    This article describes the microstructural evolution and tensile properties of Fe-Cr model alloy strengthened by nano-scale NbC particles. According to the results obtained from X-ray diffraction and transmission electron microscope with Energy Dispersive Spectrometer, the bcc ultrafine grains and the disordered phase of Nb-rich nano-clusters were observed in the milled powders. The hot pressing (HP) resulted in a nearly equiaxed ferritic grains and dispersed nano-scale NbC (~8 nm) particles. The microstructure studies reveal that the formation of NbC nanoparticles is composed of nucleation and growth of the Nb-rich nano-clusters involving diffusion of their component. At room temperature the material exhibits an ultimate tensile strength of 700 MPa, yield strength of 650 MPa, and total elongation of 11.7 pct. The fracture surface studies reveal that a typical ductile fracture mode has occurred during tensile test.

  1. In situ synthesis of NiAl–NbB2 composite powder through combustion synthesis

    International Nuclear Information System (INIS)

    Shokati, Ali Akbar; Parvin, Nader; Sabzianpour, Naser; Shokati, Mohammad; Hemmati, Ali

    2013-01-01

    Highlights: ► A Novel NiAl matrix composite powder with 0–40 wt.% NbB 2 was synthesized. ► Composite powders were synthesized by thermal explosion reaction of Ni–Al–Nb–B system. ► Microhardness of NiAl considerably increased with raising NbB 2 content. ► Synthesized composite powders is a good candidate as precursor for thermal barrier application. - Abstract: Synthesis of a novel NiAl matrix composite powder reinforced with 0–40 wt.% NbB 2 by combustion synthesis in thermal explosion mode was investigated. The elemental powders of Ni, Al, Nb, and amorphous boron were used as starting material. For all compositions final products consisted of only the NiAl and NbB 2 phases. Coarser NbB 2 with a relatively uniform distribution in NiAl matrix was formed with rising NbB 2 content. Microhardness of NiAl considerably increased from 377 ± 13 HV 0.05 to 866 ± 81 HV 0.05 for NiAl with 40 wt.% NbB 2 . High microhardness, proper size and distribution of NbB 2 in NiAl matrix make it a good candidate as precursor for thermal spray application.

  2. Contrasting origin of two A-type rhyolite series from the Early Permian Nomgon bimodal volcanic association (Southern Mongolia)

    Science.gov (United States)

    Kozlovsky, A. M.; Yarmolyuk, V. V.; Savatenkov, V. M.; Kudryashova, E. A.

    2017-08-01

    A-type rhyolites of contrasting compositions and eruption characters were revealed among two volcanic series of the Early Permian bimodal association in the Nomgon graben. Rhyolites of the lower volcanic series formed extrusions, lava domes, and tuff horizons. They had low FeOt, Zr, Hf, Nb, Ta, Y, and REE concentrations and also a moderately depleted Nd isotope composition (ɛNd( T) = 6.7-7.1). Their formation was related to anatexis of the juvenile continental crust, triggered by the thermal effect of mafic magmas. Rhyolites of the upper volcanic series formed extensive lava flows and dikes. Their composition was characterized by high FeOt, Zr, Hf, Nb, Ta, Y, and REE concentrations, and also depleted Nd isotope characteristics (ɛNd( T) = 7.7-9.0). These rhyolite melts formed under long-term crystallizational differentiation of basaltoids in the intracrustal magmatic chambers, with limited participation of crustal contamination. The source of magmas for the upper volcanic series was the sublithospheric mantle.

  3. The attenuation of the levitation force of HTS bulk exposed to AC magnetic field on the above NdFeB guideway

    International Nuclear Information System (INIS)

    Liu Minxian; Wang Yan

    2012-01-01

    The characteristic of the levitation force relaxation was studied by experiment. The levitation force is attenuated with the application of the AC external magnetic field. The decay increases with the amplitude of the A external magnetic field. The decay is almost independent of the frequency of AC field. In the present High Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets make the magnetic fields above the NdFeB guideway non-uniform. So it is required to study the characteristics of levitation force of the HTS bulk affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we have studied the characteristics of the levitation force relaxation by an experiment in which AC magnetic field generated by an electromagnet is used to simulate the time-varying magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it is found that the levitation force is attenuated with the application of the AC field, and the attenuation is increased with the amplitude of the AC field, but the attenuation is almost independent of the frequency the AC magnetic field.

  4. The attenuation of the levitation force of HTS bulk exposed to AC magnetic field on the above NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Liu Minxian, E-mail: liukey_sjtu@263.net [School of Computer Science and Technology, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Wang Yan [Luoyang Institute of Science and Technology, Luoyang, Henan 471023 (China)

    2012-01-15

    The characteristic of the levitation force relaxation was studied by experiment. The levitation force is attenuated with the application of the AC external magnetic field. The decay increases with the amplitude of the A external magnetic field. The decay is almost independent of the frequency of AC field. In the present High Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets make the magnetic fields above the NdFeB guideway non-uniform. So it is required to study the characteristics of levitation force of the HTS bulk affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we have studied the characteristics of the levitation force relaxation by an experiment in which AC magnetic field generated by an electromagnet is used to simulate the time-varying magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it is found that the levitation force is attenuated with the application of the AC field, and the attenuation is increased with the amplitude of the AC field, but the attenuation is almost independent of the frequency the AC magnetic field.

  5. The influence of the long time milling on the structure and magnetic properties of the Fe-Cu-Nb-Si-B powder

    International Nuclear Information System (INIS)

    Fechova, E.; Kollar, P.; Fuezer, J.; Kovac, J.; Petrovic, P.; Kavecansky, V.

    2004-01-01

    We have studied the influence of milling on the structure and magnetic properties of Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 powder prepared in a vibratory micro-mill as a function of long milling time. Three powder samples have been prepared and investigated (the first one was prepared by the milling of amorphous ribbon, the second one by milling of the same ribbon in a partially nanocrystallized state and the third one by milling of pure elements). Structural analysis shows the decrease of the grain size with the increasing time of milling. The coercivity of the samples prepared from pure elements increases almost linearly up to 1700 h of milling while further milling leads to the saturation at 25 kA/m (at the milling time of 3500 h). The coercivity of the samples milled from ribbons increases to its maximum of 8 kA/m for the milling time of 800 h and then decreases

  6. Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1 -yCoyGe films

    Science.gov (United States)

    Spencer, Charles S.; Gayles, Jacob; Porter, Nicholas A.; Sugimoto, Satoshi; Aslam, Zabeada; Kinane, Christian J.; Charlton, Timothy R.; Freimuth, Frank; Chadov, Stanislav; Langridge, Sean; Sinova, Jairo; Felser, Claudia; Blügel, Stefan; Mokrousov, Yuriy; Marrows, Christopher H.

    2018-06-01

    Epitaxial films of the B20-structure compound Fe1 -yCoyGe were grown by molecular beam epitaxy on Si (111) substrates. The magnetization varied smoothly from the bulklike values of one Bohr magneton per Fe atom for FeGe to zero for nonmagnetic CoGe. The chiral lattice structure leads to a Dzyaloshinskii-Moriya interaction (DMI), and the films' helical magnetic ground state was confirmed using polarized neutron reflectometry measurements. The pitch of the spin helix, measured by this method, varies with Co content y and diverges at y ˜0.45 . This indicates a zero crossing of the DMI, which we reproduced in calculations using first-principles methods. We also measured the longitudinal and Hall resistivity of our films as a function of magnetic field, temperature, and Co content y . The Hall resistivity is expected to contain contributions from the ordinary, anomalous, and topological Hall effects. Both the anomalous and topological Hall resistivities show peaks around y ˜0.5 . Our first-principles calculations show a peak in the topological Hall constant at this value of y , related to the strong spin polarization predicted for intermediate values of y . Our calculations predict half-metallicity for y =0.6 , consistent with the experimentally observed linear magnetoresistance at this composition, and potentially related to the other unusual transport properties for intermediate value of y . While it is possible to reconcile theory with experiment for the various Hall effects for FeGe, the large topological Hall resistivities for y ˜0.5 are much larger than expected when the very small emergent fields associated with the divergence in the DMI are taken into account.

  7. Hyperfine spectroscopic study of Laves phase HfFe2

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Novakovic, N.; Cekic, B.; Ivanovic, N.; Manasijevic, M.

    2004-01-01

    Hyperfine fields in HfFe 2 were measured at 181 Ta probe using the time-differential perturbed angular correlation method (TDPAC) in the temperature range 78-1200 K. Analysis of the spectra revealed two interactions with hyperfine fields of 13.82(7) T and 8.0(2) T, at 293 K. First is ascribed to the interaction at the 8a position in the cubic C15 structure. The second can be assigned to a minor amount of hexagonal C14 phase, or to an irregular position of the probe in the C15 lattice. Results of calculations using LAPW-WIEN97 are in a good agreement with experiment

  8. Influence of cobalt content on the structure and hard magnetic properties of nanocomposite (Fe,Co)-Pt-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grabias, A., E-mail: agnieszka.grabias@itme.edu.pl [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Kopcewicz, M. [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Latuch, J.; Oleszak, D. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Pękała, M. [Department of Chemistry, University of Warsaw, Al. Żwirki i Wigury 101, 02-089 Warsaw (Poland); Kowalczyk, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland)

    2017-07-15

    Highlights: • Nanocomposite alloys were formed by annealing of the rapidly quenched alloys. • Magnetically hard L1{sub 0} (Fe,Co)Pt and soft (Fe,Co){sub 2}B or (Fe,Co)B were formed. • Mössbauer spectra revealed Co substitution for Fe in L1{sub 0} FePt, FeB and Fe{sub 2}B phases. • Annealed alloys exhibit hard magnetic properties which depend on phase compositions. • Co addition was found to decrease the magnetization and the energy product. - Abstract: The influence of Co content on the structural and hard magnetic properties of two sets of nanocrystalline Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} (x = 0–26) and Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} (y = 0–40) alloys was studied. The alloys were prepared as ribbons by the rapid quenching technique. The nanocomposite structure in the alloys was obtained by annealing at 840–880 K for 30 min. Structural characterization of the samples was performed using the Mössbauer spectroscopy and X-ray diffraction. Magnetic properties of the samples were studied by the measurements of the hysteresis loops and of the magnetization at increasing temperatures. An amorphous phase prevailed in the as-quenched Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} alloys while a disordered solid solution of fcc-(Fe,Co)Pt was a dominating phase in the Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} ribbons. Differential scanning calorimetry measurements revealed one or two exothermic peaks at temperatures up to 993 K, depending on the composition of the alloys. Thermal treatment of the samples led to the formation of the magnetically hard ordered L1{sub 0} tetragonal (Fe,Co)Pt nanocrystallites and magnetically softer phases of (Fe,Co)B (for Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20}) or (Fe,Co){sub 2}B (for Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15}). Detailed Mössbauer spectroscopy studies revealed that cobalt substituted for iron in both the L1{sub 0} phase and in iron borides. The nanocomposite Fe{sub 60−y}Co{sub y

  9. Structural, dielectric and magnetic studies of Ba and Nb codoped BiFeO{sub 3} multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Jangra, Sandhaya, E-mail: sndh17@gmail.com; Sanghi, Sujata; Agarwal, Ashish; Kaswan, Kavita; Rangi, Manisha; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar, Haryana-125001 (India)

    2016-05-23

    Polycrystalline materials with composition Bi{sub 0.8}Ba{sub 0.2}Fe{sub 1-x}Nb{sub x}O{sub 3} (x= 0.07, 0.10) were prepared via solid state reaction method. Preliminary analysis of structure was performed by XRD technique and confirmed formation of single phase crystalline materials. Rietveld refinement reveled that these materials have rhombohedral phase with R3c space group. Dielectric constant increased with temperature and Nb concentration. Ba and Nb co-doping suppress the spiral spin structure and produce net magnetization.

  10. Aleaciones de aluminio amorfas y nanoestructuradas

    Directory of Open Access Journals (Sweden)

    García-Escorial, A.

    1998-05-01

    Full Text Available The work carried out in CENIM on amorphous and nanostructured aluminium alloys is described. Results about Al-LTM-ETM, Al-Fe-Nb and Al-Cu-Zr, and Al-LTM-RE, Al-Fe-Nd (LTM = Late Transition Metal, ETM = Early Transition Metal y RE = Rare Earth alloys obtained by rapid solidification, inert gas atomization and melt-spinning, as well as mechanical alloying are presented.

    En este trabajo se recoge la labor desarrollada en el CENIM en aleaciones de base aluminio amorfas y nanoestructuradas. Se presentan los resultados obtenidos hasta ahora en el estudio de aleaciones Al-LTM-ETM, Al-Fe-Nb y Al-Cu-Zr, y Al-LTM-RE, Al-Fe-Nd (LTM = Late Transition Metal, ETM = Early Transition Metal y RE = Rare Earth, procesadas por solidificación rápida, mediante atomización por gas inerte y temple ultrarrápido sobre rueda, así como por aleado mecánico en molino de bolas de alta energía.

  11. On the origin of discontinuity of the hyperfine fields at {sup 57}Fe nuclei in bulk iron and aerosol Fe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Yu.I. [Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygin str. 4, 119991, GSP-1, Moscow (Russian Federation); Shafranovsky, E.A., E-mail: shafr@chph.ras.r [Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygin str. 4, 119991, GSP-1, Moscow (Russian Federation); Casas, Ll. [Departament de Geologia, Universitat Autonoma de Barcelona, Edifici C, Campus de la UAB, 08193 Bellaterra (Spain); Molins, E. [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra (Spain)

    2011-03-14

    Advancing the early work in which a discontinuity of hyperfine fields at {sup 57}Fe nuclei in bulk iron and in aerosol Fe nanoparticles has been revealed by analyzing their Moessbauer spectra the present Letter evidences that the existence of several peaks in the hyperfine distribution (HFD) for bulk Fe is caused with the internal magnetic fields owing to its multidomain structure whereas aerosol Fe nanoparticles are single-domain and show only a unique peak in HFD. This argument has been corroborated by transformation of the HFD pattern for Fe foil after applying the external magnetic field of 0.03 T.

  12. Influence of maglev force relaxation on the forces of bulk HTSC subjected to different lateral displacements above the NdFeB guideway

    International Nuclear Information System (INIS)

    Qin Yujie; Hou Xiaojing

    2011-01-01

    Research highlights: → The relaxation properties of maglev forces have been investigated simultaneously. → Influence of relaxation on forces of HTSC subjected to different LDs above PMG is different. → The influence is explained based on motion of flux lines, re/demagnetization of HTSC during LD. → The work provide a scientific analysis for the practical application of the bulk HTSC. - Abstract: This paper studied the influence of maglev force relaxation on the force (both levitation and guidance forces) of bulk high-temperature superconductor (HTSC) subjected to different lateral displacements above a NdFeB guideway. Firstly, the maglev forces relaxation property of bulk HTSC above the permanent-magnet guideway (PMG) was studied experimentally, then the levitation and guidance forces were measured by SCML-2 measurement system synchronously at different lateral displacements, some times later(after relaxation), the forces were measured again as the same way. Compared to the two measured results, it was found that the change of the levitation force was larger compared to the case without relaxation, while the change of the guidance force was smaller. In addition, the rate of change of levitation force and guidance force was different for different maximum lateral displacements. This work provided a scientific analysis for the practical application of the bulk HTS.

  13. Influence of maglev force relaxation on the forces of bulk HTSC subjected to different lateral displacements above the NdFeB guideway

    Energy Technology Data Exchange (ETDEWEB)

    Qin Yujie, E-mail: qyjswjtu@vip.sohu.co [Department of Computer and Information Engineering, Luoyang Institute of Science and Technology, Luoyang, Henan 471023 (China); Hou Xiaojing [Department of Computer and Information Engineering, Luoyang Institute of Science and Technology, Luoyang, Henan 471023 (China)

    2011-02-15

    Research highlights: {yields} The relaxation properties of maglev forces have been investigated simultaneously. {yields} Influence of relaxation on forces of HTSC subjected to different LDs above PMG is different. {yields} The influence is explained based on motion of flux lines, re/demagnetization of HTSC during LD. {yields} The work provide a scientific analysis for the practical application of the bulk HTSC. - Abstract: This paper studied the influence of maglev force relaxation on the force (both levitation and guidance forces) of bulk high-temperature superconductor (HTSC) subjected to different lateral displacements above a NdFeB guideway. Firstly, the maglev forces relaxation property of bulk HTSC above the permanent-magnet guideway (PMG) was studied experimentally, then the levitation and guidance forces were measured by SCML-2 measurement system synchronously at different lateral displacements, some times later(after relaxation), the forces were measured again as the same way. Compared to the two measured results, it was found that the change of the levitation force was larger compared to the case without relaxation, while the change of the guidance force was smaller. In addition, the rate of change of levitation force and guidance force was different for different maximum lateral displacements. This work provided a scientific analysis for the practical application of the bulk HTS.

  14. Grain Boundary Analysis of the Garnet-Like Oxides Li{sub 7+X−Y}La{sub 3−X}A{sub X}Zr{sub 2−Y}Nb{sub Y}O{sub 12} (A = Sr or Ca)

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Shingo, E-mail: shingo_ohta@mail.toyota.co.jp; Kihira, Yuki; Asaoka, Takahiko [Battery & Cell Division, Toyota Central R& D Labs. Inc., Nagakute (Japan)

    2016-07-28

    Garnet-like oxides having the formula Li{sub 7+X−Y}La{sub 3−X}A{sub X}Zr{sub 2−Y}Nb{sub Y}O{sub 12} (A = Sr or Ca) were synthesized using a solid-state reaction, and their bulk and grain boundary resistivities were assessed by AC impedance measurements. A difference in grain boundary resistivity was identified between Sr and Ca materials, and so the grain boundaries were examined using electron probe microanalysis (EPMA). The difference in the grain boundary resistivities was attributed to the core–shell structure of the Sr-substituted samples. In contrast, the Ca-substituted materials exhibited accumulations of impurities at the grain boundaries.

  15. Magnetic and magnetocaloric properties of itinerant-electron system Hf{sub 1−x}Ta{sub x}Fe{sub 2} (x = 0.125 and 0.175)

    Energy Technology Data Exchange (ETDEWEB)

    Diop, L.V.B. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Kastil, J. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Isnard, O. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Arnold, Z.; Kamarad, J. [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2015-04-05

    Highlights: • First report of the direct measurement of ΔT{sub ad} in Hf{sub 1−x}Ta{sub x}Fe{sub 2} compounds. • ΔT{sub ad} reach values of 2.5 K under μ{sub 0}ΔH = 3 T for x = 0.175 compound. • A field induced metamagnetic phase transition has been observed. - Abstract: Intrinsic magnetic properties and magnetocaloric effect (MCE) have been investigated for Hf{sub 1−x}Ta{sub x}Fe{sub 2} (x = 0.125 and 0.175) itinerant-electron compounds which exhibit a temperature-induced transition from the ferromagnetic (FM) to the antiferromagnetic (AFM) state. Upon increasing Ta concentration, the ferromagnetic ordering temperature strongly decreases with decreasing the lattice parameters and both the isothermal magnetic entropy change ΔS{sub M} and the adiabatic temperature change ΔT{sub ad} are enhanced. An adiabatic temperature change of ΔT{sub ad} = 2 and 2.5 K was observed in Hf{sub 0.875}Ta{sub 0.125}Fe{sub 2} and Hf{sub 0.825}Ta{sub 0.175}Fe{sub 2}, respectively, for a magnetic field change of 3 T. Therefore, the partial substitution of Ta for Hf is highly effective in the enhancement of the magnetocaloric effect in Hf{sub 1−x}Ta{sub x}Fe{sub 2} systems. In addition substitution can be used to tune both the transition temperature but also the magnetic transition from first toward second order type.

  16. A binomial truncation function proposed for the second-moment approximation of tight-binding potential and application in the ternary Ni-Hf-Ti system

    International Nuclear Information System (INIS)

    Li, J H; Dai, X D; Wang, T L; Liu, B X

    2007-01-01

    We propose a two-parameter binomial truncation function for the second-moment approximation of the tight-binding (TB-SMA) interatomic potential and illustrate in detail the procedure of constructing the potentials for binary and ternary transition metal systems. For the ternary Ni-Hf-Ti system, the lattice constants, cohesion energies, elastic constants and bulk moduli of six binary compounds, i.e. L1 2 Ni 3 Hf, NiHf 3 , Ni 3 Ti, NiTi 3 , Hf 3 Ti and HfTi 3 , are firstly acquired by ab initio calculations and then employed to derive the binomial-truncated TB-SMA Ni-Hf-Ti potential. Applying the ab initio derived Ni-Hf-Ti potential, the lattice constants, cohesive energy, elastic constants and bulk moduli of another six binary compounds, i.e. D0 3 NiHf 3 , NiTi 3 HfTi 3 , and B2 NiHf, NiTi, HfTi, and two ternary compounds, i.e. C1 b NiHfTi, L2 1 Ni 2 HfTi, are calculated, respectively. It is found that, for the eight binary compounds studied, the calculated lattice constants and cohesion energies are in excellent agreement with those directly acquired from ab initio calculations and that the elastic constants and bulk moduli calculated from the potential are also qualitatively consistent with the results from ab initio calculations

  17. Morphology effect on photocatalytic activity in Bi3Fe0.5Nb1.5O9

    Science.gov (United States)

    Yin, Xiaofeng; Li, Xiaoning; Gu, Wen; Zou, Wei; Liu, Huan; Zhu, Liuyang; Fu, Zhengping; Lu, Yalin

    2018-06-01

    In this work, the Aurivillius-phase ferroelectric Bi3Fe0.5Nb1.5O9 were synthesized by hydrothermal (BFNO-H) and solid state methods (BFNO-S), respectively. The BFNO-H shows a hierarchical morphology, which is stacked by intersecting single-crystal nanosheets with {001} and {110} exposed facets, while the BFNO-S shows disorganized micron-scale morphology. BFNO-H shows a much stronger photodegradation activity (10.4 times and 9.8 times) than BFNO-S in the visible-light photodegradation of rhodamine B (RhB) and salicylic acid. The higher photodegradation activity of BFNO-H was firstly ascribed to the hierarchical structure and the larger specific surface area (16.586 m2 g‑1) because a large specific surface area can increase reactive sites and shorten photogenerated carrier migration distance. However, after being normalized by the specific surface area, BFNO-H still performs better than BFNO-S, implying that the specific surface area is not the only factor that determines the photocatalytic activity. Considering that the built-in electric field originating from spontaneous polarization in Bi3Fe0.5Nb1.5O9 has existed in both ab plane and c direction, it matches well with the {001} and {110} exposed facets of BFNO-H nanosheets. This appropriate matching in BFNO-H nanosheets may improve the separation and transmission of photogenerated electron–hole pairs and further enhance its photocatalytic activity. Moreover, the trapping experiments reveals that holes (h +) are the main active species and hole-derived oxidation is the main redox reaction during photodegradation of organic pollutions.

  18. Role of aluminium addition on structure of Fe substituted Fe73· 5 ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Role of aluminium addition on structure of Fe substituted Fe73.5−Si13.5B9Nb3Cu1Al alloy ribbons. Gautam Agarwal Himanshu Agrawal M Srinivas B Majumdar N K Mukhopadhyay. Volume 36 Issue 4 August 2013 pp 613-618 ...

  19. The magnetic hyperfine field in the 181Ta site in the Co2HfAl and Co2HfGa Heusler alloys

    International Nuclear Information System (INIS)

    Silva, R. da.

    1979-01-01

    The hyperfine magnetic fields at 181 Ta nuclei in Heusler alloys Co 2 HfZ (Z=Al, Ga) have been measured using the time differential perturbed gamma-gamma angular correlation (TDPAC) method. The hyperfine fields obtained from these measurements at the liquid nitrogen temperature are -189 and +- 150 kOersted for Co 2 HfAl and Co 2 HfGa, respectively. The concept that the hyperfine field at the Y site is similar to the solute fields in Fe, Co, Ni and Gd matrices is corroborated. We have verified that ratios H sub(hf) sub(Ta)/T sub(c) and H sub(hf) sub(Ta)μ sub(Co) in Co 2 HfZ compounds (Z=Al, Ga, Sn) do not depend on the nature of Z element. However a dependence in the value of observed field with the s-p element in Z site was noticed. We feel that the samples are not completely ordered cubic as observed by the quadrupole interaction measurements. The results are interpreted in terms of the Campbell-Blandin formalism, and it is shown that the spin polarization of conduction electrons at Hf and Ta have opposite signs. (Author) [pt

  20. Hf isotope evidence for a hidden mantle reservoir

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2002-01-01

    High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir-marked by an unradiogenic...... Hf isotopic composition and preserved in the deep mantle for at least 3 b.y.-may account for the mass imbalance in Earth's Hf-Nd budget. The Hf isotopic data presented here support a common mantle source region and genetic link between carbonatite and some oceanic-island basalt volcanoes....

  1. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    Energy Technology Data Exchange (ETDEWEB)

    Lollobrigida, V. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Torino (Italy); Borgatti, F. [CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), I-40129 Bologna (Italy); Torelli, P.; Panaccione, G. [CNR, Istituto Officina dei Materiali (IOM), Lab. TASC, I-34149 Trieste (Italy); Tortora, L. [Laboratorio di Analisi di Superficie, Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Ingegneria Meccanica, Università Tor Vergata, I-00133 Rome (Italy); Stefani, G.; Offi, F. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy)

    2014-05-28

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  2. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    Science.gov (United States)

    Lollobrigida, V.; Basso, V.; Borgatti, F.; Torelli, P.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F.; Tortora, L.; Stefani, G.; Panaccione, G.; Offi, F.

    2014-05-01

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  3. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    International Nuclear Information System (INIS)

    Lollobrigida, V.; Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F.; Borgatti, F.; Torelli, P.; Panaccione, G.; Tortora, L.; Stefani, G.; Offi, F.

    2014-01-01

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  4. Electric-field-control of magnetic anisotropy of Co0.6Fe0.2B0.2/oxide stacks using reduced voltage

    Science.gov (United States)

    Kita, Koji; Abraham, David W.; Gajek, Martin J.; Worledge, D. C.

    2012-08-01

    We have demonstrated purely electrical manipulation of the magnetic anisotropy of a Co0.6Fe0.2B0.2 film by applying only 8 V across the CoFeB/oxide stack. A clear transition from in-plane to perpendicular anisotropy was observed. The quantitative relationship between interface anisotropy energy and the applied electric-field was determined from the linear voltage dependence of the saturation field. By comparing the dielectric stacks of MgO/Al2O3 and MgO/HfO2/Al2O3, enhanced voltage control was also demonstrated, due to the higher dielectric constant of the HfO2. These results suggest the feasibility of purely electrical control of magnetization with small voltage bias for spintronics applications.

  5. TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened ferritic steel with Hf addition

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Peng, E-mail: doup@tsinghua.edu.cn [School of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko, E-mail: kimura@iae.kyoto-u.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kasada, Ryuta, E-mail: r-kasada@iae.kyoto-u.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Okuda, Takanari, E-mail: okuda.takanari@kki.kobelco.com [Kobelco Research Institute, 1-5-5 Takatsukadai, Nishi-ku, Kobe, Hyogo 651-2271 (Japan); Inoue, Masaki, E-mail: inoue.masaki@jaea.go.jp [Advanced Nuclear System R& D Directorate, Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki 311-1393 (Japan); Ukai, Shigeharu, E-mail: s-ukai@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-ku, Sapporo 060-8628 (Japan); Ohnuki, Somei, E-mail: ohnuki@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-ku, Sapporo 060-8628 (Japan); Fujisawa, Toshiharu, E-mail: fujisawa@esi.nagoya-u.ac.jp [EcoTopia Science Institute, Nagoya University, Furo, Chikusa-ku, Nagoya 464-8603 (Japan); Abe, Fujio, E-mail: ABE.Fujio@nims.go.jp [Structural Metals Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Jiang, Shan, E-mail: js93518@gmail.com [School of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Yang, Zhigang, E-mail: zgyang@tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Sciences and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-03-15

    The nanoparticles in an Al-alloyed high-Cr oxide dispersion strengthened (ODS) ferritic steel with Hf addition, i.e., SOC-16 (Fe-15Cr-2W-0.1Ti-4Al-0.62Hf-0.35Y{sub 2}O{sub 3}), have been examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Relative to an Al-alloyed high-Cr ODS ferritic steel without Hf addition, i.e., SOC-9 (Fe-15.5Cr-2W-0.1Ti-4Al-0.35Y{sub 2}O{sub 3}), the dispersion morphology and coherency of the oxide nanoparticles in SOC-16 were significantly improved. Almost all the small nanoparticles (diameter <10 nm) in SOC-16 were found to be consistent with cubic Y{sub 2}Hf{sub 2}O{sub 7} oxides with the anion-deficient fluorite structure and coherent with the bcc steel matrix. The larger particles (diameter >10 nm) were also mainly identified as cubic Y{sub 2}Hf{sub 2}O{sub 7} oxides with the anion-deficient fluorite structure. The results presented here are compared with those of SOC-9 with a brief discussion of the underlying mechanisms of the unusual thermal and irradiation stabilities of the oxides as well as the superior strength, excellent irradiation tolerance and extraordinary corrosion resistance of SOC-16.

  6. Bioactivity and structural properties of nanostructured bulk composites containing Nb2O5 and natural hydroxyapatite

    Science.gov (United States)

    Bonadio, T. G. M.; Sato, F.; Medina, A. N.; Weinand, W. R.; Baesso, M. L.; Lima, W. M.

    2013-06-01

    In this work, we investigate the bioactivity and structural properties of nanostructured bulk composites that are composed of Nb2O5 and natural hydroxyapatite (HAp) and are produced by mechanical alloying and powder metallurgy. X-ray diffraction and Raman spectroscopy data showed that the milling process followed by a heat treatment at 1000 °C induced chemical reactions along with the formation of the CaNb2O6, PNb9O25 and Ca3(PO4)2 phases. Rietveld refinement indicated significant changes in each phase weight fraction as a function of HAp concentration. These changes influenced the in vitro bioactivity of the material. XRD and FTIR analyses indicated that the composites exhibited bioactivity characteristics by forming a carbonated apatite layer when the composites were immersed in a simulated body fluid. The formed layers had a maximum thickness of 13 μm, as measured by confocal Raman spectroscopy and as confirmed by scanning electron microscopy. The results of this work suggest that the tested bulk composites are promising biomaterials for use in implants.

  7. Zircon U–Pb–Hf isotopic and geochemical characteristics of the Xierzi biotite monzogranite pluton, Linxi, Inner Mongolia and its tectonic implications

    Directory of Open Access Journals (Sweden)

    Qing-Bin Guan

    2018-03-01

    Full Text Available The opening, subduction and final closure of the Paleo-Asian Ocean led to the formation of the Central Asian Orogenic Belt. Controversy has long surrounded the timing of final closure of the Paleo-Asian Ocean. Here we present zircon U–Pb ages and petrological, geochemical and in situ Hf isotope data for the Xierzi biotite monzogranite pluton, Linxi, SE Inner Mongolia. U–Pb dating of zircon by LA-ICP-MS yields a middle Permian emplacement age (268.7 ± 2.3 Ma for the Xierzi pluton that is dominated by biotite monzogranites with high SiO2 (71.2–72.8 wt.%, alkali (Na2O + K2O = 8.05–8.44 wt.%, Al2O3 (14.4–15.2 wt.% and Fe2O3T relative to low MgO contents, yielding Fe2O3T/MgO ratios of 2.87–3.44, and plotting within the high-K calc-alkaline field on a SiO2 vs. K2O diagram. The aluminum saturation indexes (A/CNK of the biotite monzogranites range from 1.06 to 1.19, corresponding to weakly to strongly peraluminous. They are enriched in rare earth elements (REE, high field strength elements (HFSEs; Zr, Hf, and large ion lithophile elements (LILEs; Rb, U, Th. The LREEs are enriched relative to the HREEs, with a distinct negative Eu anomaly in a chondrite–normalized REE diagram. Geochemically, the Xierzi biotite monzogranite is classified as an aluminous A-type granite, with all samples plotting within the A2-type granite field on a Y/Nb vs. Rb/Nb diagram. Zircon εHf(t values and two-stage modal ages of the zircons within the pluton range from +4.80 to +13.65 and from 983 to 418 Ma, respectively, indicating that the primary magma was generated through partial melting of felsic rocks from juvenile crust. Consequently, these results demonstrate that the Xierzi pluton formed under the post-orogenic extensional setting after arc–continent collision in the middle Permian.

  8. Desarrollo de materiales de base Fe a partir de la síntesis de precursores por aleado mecánico

    Directory of Open Access Journals (Sweden)

    González, A.

    2005-12-01

    Full Text Available Fe rich alloys with ZrNi or Nb and with non metallic B were developed by means of mechanical alloying. The material is nanocrystalline with a minoritary amorphous phase (about 12%. The reduction of the crystallite size is favoured by the addition of Zr, Nb or B. The mechanical alloying parameters were optimised to obtain a nanocrystalline state at low milling time. Furthermore, the apparent activation energy of the crystallisation processes was obtained by thermal treatment, controlled by differential scanning calorimetry. Typical values between 280 and 410 kJ mol-1 are associated to crystalline growth. The control of the crystal size is related to the kinetic study of the non-equilibrium transformations where the incipient phase as different composition that the initial phase.

    Se han producido mediante síntesis mecánica aleaciones ricas en Fe, con Zr o Nb y con un no metal, B obteniéndose materiales nanoestructurados con una incipiente fase amorfa (entorno 12%. Tanto el Zr y el Nb como el B facilitan la reducción del tamaño de los nanocristales. Se han optimizado las condiciones de proceso, minimizando el tiempo de molturación. Además, el posterior tratamiento térmico, controlado mediante calorimetría diferencial, de las diferentes aleaciones permite obtener la energía de activación de los procesos de cristalización, con valores entre 280 y 410 kJ mol-1 asociados al crecimiento cristalino. El control del tamaño de los nanocristales se enmarca en el estudio de la cinética de las transformaciones fuera del equilibrio en las que la fase incipiente tiene composición diferente a la de la fase inicial.

  9. Nonequilibrium synthesis of Nb-Al alloys by laser processing

    International Nuclear Information System (INIS)

    Tewari, S.K.; Mazumder, J.

    1993-01-01

    The technique of laser surface modification provides a unique means of synthesizing novel nonequilibrium materials in near net shape. Claddings of several NbAl 3 alloys with Ti, B and Hf as a ternary alloy addition were prepared using a CW CO 2 laser. Isothermal oxidation behavior of the clads were examined in air. Oxidation tests at 800, 1,200 and 1,400 C. Alternating layers of alumina and NbAlO 4 were not observed in any of the samples as reported in literature for conventionally processed NbAl 3 oxidized under similar conditions. The parabolic rate constants for all the alloys, except 0 B, were comparable to that for isothermal oxidation of β-NiAl, at 1,200 and 1,400 C in 0.1 atm oxygen, which is a known alumina former. Ternary alloying additions for improved oxidation resistance at 1,400 C accompanied with improved ductility were identified

  10. Ferromagnetic resonance on oxideless magnetic Fe and FeRh nanoparticles

    International Nuclear Information System (INIS)

    Trunova, Anastasia

    2009-01-01

    This work is dedicated to investigations of structural and magnetic properties of the colloidal Fe/Fe x O y nanocubes (13 nm) and the Fe x Rh 100-x core/shell nanoparticles (2 nm). As compared with other works, where the measurements on oxidized nanoparticles were carried out, we additionally performed investigations on nanoparticles in an oxide free state. In order to make the measurements on oxide free particles possible, oxygen- and hydrogenplasma was used to remove the ligands and reduce the oxide shell of the Fe nanocubes. The oxide free Fe nanocubes were covered with a Ag/Pt protective coating to prevent them from new oxidation. This method allowed carrying out the magnetic measurements on oxide free Fe nanocubes. Micromagnetic simulations as well as simulations of the high frequency susceptibility were used for the data analysing. It was found that both the g-factor g=2.09±0.01 and the anisotropy constant K 4 =(4.8±0.5).10 4 J/m 3 coincide with that of bulk iron. However, the saturation magnetization M S (5 K)=(1.2±0.12).10 6 A/m differs from the bulk value by 30%. The reduction by 30% compared to the bulk value in the case of nanoparticles may be caused by the following possible reasons: a) the presence of inner oxide layer (approx. 10 at.%) that cannot be reduced; b) the anti-parallel order between magnetic moments of iron core and magnetic moments of antiferomagnetic iron oxide; c) some structural changes of the surface after plasma treatment. The obtained damping parameter α=0.03±0.005 is ten times larger than that of the Fe layers as it is known for nanoparticles systems in general. The core/shell Fe x Rh 100-x nanoparticles (x=80,50) were produced under Ar-atmosphere and were sealed into a quartz tube to prevent oxidation. The analysis of g-factors shows that the value for the FePh nanoparticles with Fe-rich core is larger (g=2.08±0.01) than that for the nanoparticles with Rh-rich core and coincides within error bars with the g-factor of bulk

  11. A method for increasing the homogeneity of the temperature distribution during magnetic fluid hyperthermia with a Fe-Cr-Nb-B alloy in the presence of blood vessels

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yundong [College of Physics and Information Engineering, Fuzhou University, Fuzhou 350116 (China); Flesch, Rodolfo C.C. [Departamento de Automação e Sistemas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Jin, Tao, E-mail: jintly@fzu.edu.cn [College of Electrical Engineering and Automation, Fuzhou University, Fuzhou 350116 (China)

    2017-06-15

    Highlights: • The effects of blood vessels on temperature field distribution are investigated. • The critical thermal energy of hyperthermia is computed by the Finite Element Analysis. • A treatment method is proposed by using the MNPs with low Curie temperature. • The cooling effects due to the blood flow can be controlled. - Abstract: Magnetic hyperthermia ablates tumor cells by absorbing the thermal energy from magnetic nanoparticles (MNPs) under an external alternating magnetic field. The blood vessels (BVs) within tumor region can generally reduce treatment effectiveness due to the cooling effect of blood flow. This paper aims to investigate the cooling effect of BVs on the temperature field of malignant tumor regions using a complex geometric model and numerical simulation. For deriving the model, the Navier-Stokes equation for blood flow is combined with Pennes bio-heat transfer equation for human tissue. The effects on treatment temperature caused by two different BV distributions inside a mammary tumor are analyzed through numerical simulation under different conditions of flow rate considering a Fe-Cr-Nb-B alloy, which has low Curie temperature ranging from 42 °C to 45 °C. Numerical results show that the multi-vessel system has more obvious cooling effects than the single vessel one on the temperature field distribution for hyperthermia. Besides, simulation results show that the temperature field within tumor area can also be influenced by the velocity and diameter of BVs. To minimize the cooling effect, this article proposes a treatment method based on the increase of the thermal energy provided to MNPs associated with the adoption of low Curie temperature particles recently reported in literature. Results demonstrate that this approach noticeably improves the uniformity of the temperature field, and shortens the treatment time in a Fe-Cr-Nb-B system, thus reducing the side effects to the patient.

  12. Recent development in crystal growth of large-diameter Y-QMG (reg sign) bulk superconductors; Y kei ogata QMG (reg sign) baruku koonchodendotai no kaihatsu jokyo

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, T.; Morita, M. [Nippon Steel Corporation, Tokyo (Japan); Masahashi, N. [Tohoku University, Miyagi (Japan). Institute for Materials Research

    1999-11-25

    The current status of large-diameter Y-Ba-Cu-O OMG(reg sign) bulk superconductors is described. 75 mm-diameter QMG(reg sign) samples with fairly concentric trapped-magnetic-flux-density distributions have been successfully grown. In addition, a record-high value of the magnetic levitation force, 171 kgf, measured at 77 K using a 90 mm-diameter Nd-Fe-B magnet has been obtained for a 100 mm-diameter sample. The crystal orientation of subgrains in the sample was determined using Electron Back-Scattering Diffraction as well as using a conventional optical apparatus including a He-Ne-laser. For the sample grown under normal process conditions, the maximum value of the [001]-axis misorientation angles at the subgrain-boundaries we obtained in the c-substructure region is 2.9 degree. However, in the a/b-substructure regions, the misorientation angles are larger, and the maximum value obtained is 6.6 degree, exceeding the critical angle at which a significant reduction of the critical current density occurs in Y123 thin films due to the weak-link problem. (author)

  13. Role of Nb content in nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, J. [Department of Nuclear Physics and Technology, Slovak Technical University, Ilkovicova 3, 812 19, Bratislava (Slovakia); Lipka, J. [Department of Nuclear Physics and Technology, Slovak Technical University, Ilkovicova 3, 812 19, Bratislava (Slovakia); Miglierini, M. [Department of Nuclear Physics and Technology, Slovak Technical University, Ilkovicova 3, 812 19, Bratislava (Slovakia); Toth, I. [Department of Nuclear Physics and Technology, Slovak Technical University, Ilkovicova 3, 812 19, Bratislava (Slovakia)

    1995-02-09

    The influence of Nb content on the formation of nanocrystalline phase in the Fe{sub 73.5-x}Cu{sub 1}Nb{sub 3+x}Si{sub 13.5}B{sub 9} system was studied by Moessbauer spectroscopy. The kinetics of crystallization was observed by isothermal heating at temperature 550 C during annealing time up to 16 h. The samples containing 3 and 4.5 at% were compared. Nanocrystalline phase formation was explained on the basis of cluster model. ((orig.)).

  14. Determination of the electrostatic potential distribution in Pt/Fe:SrTiO₃/Nb:SrTiO₃ thin-film structures by electron holography.

    Science.gov (United States)

    Marchewka, Astrid; Cooper, David; Lenser, Christian; Menzel, Stephan; Du, Hongchu; Dittmann, Regina; Dunin-Borkowski, Rafal E; Waser, Rainer

    2014-11-10

    We determined the electrostatic potential distribution in pristine Pt/Fe:SrTiO3/Nb:SrTiO3 structures by electron holography experiments, revealing the existence of a depletion layer extending into the Nb-doped bottom electrode. Simulations of potential profiles in metal-insulator-metal structures were conducted assuming different types and distributions of dopants. It is found that the presence of acceptor-type dopant concentrations at the Fe:SrTiO3/Nb:SrTiO3 interface with a donor-doped insulating layer provides a good match to the measured profile. Such acceptor-type interface concentrations may be associated with Sr vacancies on the Nb:SrTiO3 side of the bottom interface.

  15. Structural and magnetic properties of NdFeB and NdFeB/Fe films with Mo addition

    Energy Technology Data Exchange (ETDEWEB)

    Urse, M; Grigoras, M; Lupu, N; Chiriac, H, E-mail: urse@phys-iasi.ro [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)

    2011-07-06

    The influence of the Mo addition on the microstructure and magnetic properties of Nd-Fe-B and Nd-Fe-B/Fe films was studied. The coercivity is a key parameter in the control of technical performances of Nd-Fe-B films. A small amount of about 1 at.% Mo can enhance the coercivity of Nd-Fe-B film by controlling the growth of soft and hard magnetic grains. A coercivity of 22.1 kOe, a remanence ratio, M{sub r}/M{sub s}, of 0.83 and a maximum energy product of 8 MGOe were obtained for Ta/[NdFeBMo(1at.%)(540nm)/Ta films annealed at 650{sup 0}C for 20 minutes due to Mo precipitates formed at the Nd{sub 2}Fe{sub 14}B phase boundaries which prevent the nucleation and expansion of the magnetic domains. Simultaneous use of Mo as addition and the stratification of Nd-Fe-B-Mo films using Fe as spacer layer are important tools for the improvement of the hard magnetic properties of Nd-Fe-B films. The Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta multilayer film annealed at 620{sup 0}C exhibits an increase in the coercivity from 12.1 kOe to 22.8 kOe, in the remanence ratio from 0.77 to 0.80, and in the maximum energy product from 4.5 to 7.1 MGOe in comparison with Ta/Nd-Fe-B/Ta film. As compared to Ta/Nd-Fe-B/Ta film, the Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta film presents a decrease in the crystallization temperature of about 30{sup 0}C.

  16. A novel Fe–Cr–Nb matrix composite containing the TiB{sub 2} neutron absorber synthesized by mechanical alloying and final hot isostatic pressing (HIP) in the Ti-tubing

    Energy Technology Data Exchange (ETDEWEB)

    Litwa, Przemysław [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Perkowski, Krzysztof [Department of Nanotechnology, Institute of Ceramics and Building Materials, Postępu 9, 02-676 Warsaw (Poland); Zasada, Dariusz [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Kobus, Izabela; Konopka, Gustaw [Department of Nanotechnology, Institute of Ceramics and Building Materials, Postępu 9, 02-676 Warsaw (Poland); Czujko, Tomasz [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Varin, Robert A., E-mail: robert.varin@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., Waterloo, ON N2L 3G1 (Canada)

    2016-07-25

    The Fe–Cr–Ti-Nb elemental powders were mechanically alloyed/ball milled with TiB{sub 2} and a small quantity of Y{sub 2}O{sub 3} ceramic to synthesize a novel Fe-based alloy-ceramic powder composite that could be processed by hot isostatic pressing (HIP) for a perceived potential application as a neutron absorber in nuclear reactors. After ball milling for the 30–80 h duration relatively uniform powders with micrometric sizes were produced. With increasing milling time a fraction of TiB{sub 2} particles became covered with the much softer Fe-based alloy which resulted in the formation of a characteristic “core-mantel” structure. For the final HIP-ing process the mechanically alloyed powders were initially uniaxially pressed into rod-shaped compacts and then cold isostatically pressed (CIP-ed). Subsequently, the rod-shaped compacts were placed in the Ti-tubing and subjected to hot isostatic pressing (HIP) at 1150 °C/200 MPa pressure. The HIP-ing process resulted in the formation of the near-Ti and intermediate diffusional layers in the microstructure of HIP-ed samples which formed in accord with the Fe-Ti binary phase diagram. Those layers contain the phases such as α-Ti (HCP), the FeTi intermetallic and their hypo-eutectoid mixtures. In addition, needle-like particles were formed in both layers in accord with the Ti-B binary phase diagram. Nanohardness testing, using a Berkovich type diamond tip, shows that the nanohardness in the intermediate layer areas, corresponding to the composition of the hypo-eutectoid mixture of Ti-FeTi, equals 980.0 (±27.1) HV and correspondingly 1176.9 (±47.6) HV for the FeTi phase. The nanohardness in the sample's center in the areas with the fine mixture of Fe-based alloy and small TiB{sub 2} particles equals 1048.3 (±201.8) HV. The average microhardness of samples HIP-ed from powders milled for 30 and 80 h is 588 HV and 733 HV, respectively. - Highlights: • A Fe–Cr–Nb-based composite with TiB{sub 2} neutron

  17. Physical and magnetic properties, microstructure of bonded magnet NdFeB prepared by using synthesis rubber

    International Nuclear Information System (INIS)

    Suprapedi; Sardjono, P.; Muljadi

    2016-01-01

    The magnet permanent has been made by using NdFeB (NQP-B) powder with purity 99.90% and polymer rubber with purity 90%. This research was done to determine the effect of the polymer (rubber) composition as binder in the manufacture of bonded magnet NdFeB on physical properties, microstructure and magnetic properties. Bonded magnets are magnet material made from a mixture of magnetic powder as a filler and the polymer as a matrix material or as binder to bind the magnetic particles. The NdFeB (NQP-B) powder fractions of bonded magnets NdFeB investigated were as follows: a) 97 wt.% of NdFeB (NQP-B) and 3 wt.% of rubber,b) 95wt.% of NdFeB (NQP-B) and 5 wt.% of rubber, c) 93 wt.% of NdFeB (NQP-B) and 7 wt.% of rubber, d) 91 wt.% of NdFeB (NQP-B) and 9 wt.% of rubber. Both raw materials were mixed by using mixer until homogen with total weight about 16 g for each sample, then added 0.3 ml of catalyst and mixed again and put in dies mould and compacted at pressure 30 MPa, then dried for 2 hours at room temperature. The dried samples was characterized such as: bulk density measurement and magnetic properties by using BH-curve permeagraph. The bulk density values of the sample bonded NdFeB magnets using the binder 3% wt. and 5% wt. rubber are respectively 4,70 g/cm 3 and 4.88 g/cm 3 . The result from BH- curve shows that the highest value of remanence (Br = 5.12 kGauss) is at sample with 3% wt. of rubber, but sample with 5% wt. of rubber has lowest value of remanance (Br = 4.40 kGauss). Based on the observation of the SEM photograph shown that the rubber material has been successfully covered the whole surface of the grain and fill some of the voids that are in the grain boundary. (paper)

  18. Physical and magnetic properties, microstructure of bonded magnet NdFeB prepared by using synthesis rubber

    Science.gov (United States)

    Suprapedi; Sardjono, P.; Muljadi

    2016-11-01

    The magnet permanent has been made by using NdFeB (NQP-B) powder with purity 99.90% and polymer rubber with purity 90%. This research was done to determine the effect of the polymer (rubber) composition as binder in the manufacture of bonded magnet NdFeB on physical properties, microstructure and magnetic properties. Bonded magnets are magnet material made from a mixture of magnetic powder as a filler and the polymer as a matrix material or as binder to bind the magnetic particles. The NdFeB (NQP-B) powder fractions of bonded magnets NdFeB investigated were as follows: a) 97 wt.% of NdFeB (NQP-B) and 3 wt.% of rubber,b) 95wt.% of NdFeB (NQP-B) and 5 wt.% of rubber, c) 93 wt.% of NdFeB (NQP-B) and 7 wt.% of rubber, d) 91 wt.% of NdFeB (NQP-B) and 9 wt.% of rubber. Both raw materials were mixed by using mixer until homogen with total weight about 16 g for each sample, then added 0.3 ml of catalyst and mixed again and put in dies mould and compacted at pressure 30 MPa, then dried for 2 hours at room temperature. The dried samples was characterized such as: bulk density measurement and magnetic properties by using BH-curve permeagraph. The bulk density values of the sample bonded NdFeB magnets using the binder 3% wt. and 5% wt. rubber are respectively 4,70 g/cm3 and 4.88 g/cm3. The result from BH- curve shows that the highest value of remanence (Br = 5.12 kGauss) is at sample with 3% wt. of rubber, but sample with 5% wt. of rubber has lowest value of remanance (Br = 4.40 kGauss). Based on the observation of the SEM photograph shown that the rubber material has been successfully covered the whole surface of the grain and fill some of the voids that are in the grain boundary.

  19. Structure, nonstoichiometry, sintering and oxygen permeability of perovskite SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.05, 0.10) oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jin Na [College of Chemistry and Materials Science, Liaoning University of Petroleum and Chemical Technology, Fushun 113001 (China); State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Lu, Hui, E-mail: huilu@dicp.ac.cn [Greenhouse Gas Research Center, Climate Change Technology Research Division, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of); State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Gui, Jian Zhou [College of Chemistry and Materials Science, Liaoning University of Petroleum and Chemical Technology, Fushun 113001 (China); Kim, Jong Pyo; Son, Sou Hwan [Greenhouse Gas Research Center, Climate Change Technology Research Division, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of); Park, Jung Hoon, E-mail: pjhoon@kier.re.kr [Greenhouse Gas Research Center, Climate Change Technology Research Division, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of)

    2013-04-20

    Highlights: ► The novel Fe/Nb co-substituted SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.05, 0.10) oxides were characterized by the XRD, DSC, TG and SEM–EDS. ► The high structural stability of the co-substituted SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.05, 0.10) oxides. ► The excellent oxygen permeation performance of the co-substituted SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.10) membrane. -- Abstract: The novel Fe/Nb co-substituted SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.05, 0.10) oxides have been synthesized and characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), and scanning electron microscopy (SEM). The XRD and DSC results demonstrate that the structural stability of the Fe/Nb co-substituted samples x = 0.05, 0.10 is improved greatly compared to the sample x = 0.00. The Fe/Nb co-doping in the SrCoO{sub 3−δ} oxide results in the improved structural stability of the SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.05, 0.10) oxides. The nonstoichiometric and sintering properties were investigated by TG and SEM, and the oxygen permeation fluxes were measured at 800–950 °C for the sample x = 0.10. The improved oxygen permeability of the ceramic SrCo{sub 1−2x}(Fe,Nb){sub x}O{sub 3−δ} (x = 0.10) membrane compared to the (Ba{sub 0.5}Sr{sub 0.5})(Co{sub 0.8}Fe{sub 0.2})O{sub 3−δ} and SrCo{sub 0.8}Fe{sub 0.2}O{sub 3–δ} membranes, was observed under an air/He oxygen partial pressure gradient at 800–950 °C.

  20. Electric-Field Control of Magnetism in Co40Fe40B20/(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 Multiferroic Heterostructures with Different Ferroelectric Phases.

    Science.gov (United States)

    Liu, Yan; Zhao, Yonggang; Li, Peisen; Zhang, Sen; Li, Dalai; Wu, Hao; Chen, Aitian; Xu, Yang; Han, X F; Li, Shiyan; Lin, Di; Luo, Haosu

    2016-02-17

    Electric-field control of magnetism in multiferroic heterostructures composed of Co40Fe40B20 (CoFeB) and (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) with different ferroelectric phases via changing composition and temperature is explored. It is demonstrated that the nonvolatile looplike bipolar-electric-field-controlled magnetization, previously found in the CoFeB/PMN-xPT heterostructures with PMN-xPT in the rhombohedral (R) phase around the morphotropic phase boundary (MPB), also occurs for PMN-xPTs with both R phase (far away from MPB) and monoclinic (M) phase, suggesting that the phenomenon is the common feature of CoFeB/PMN-xPT multiferroic heterostructures for PMN-xPT with different phases. The magnitude of the effect changes with increasing temperature and volatile bipolar-electric-field-controlled magnetization with a butterflylike behavior occurs when the ferroelectric phase changes to the tetragonal phase (T). Moreover, for the R-phase sample with x = 0.18, an abrupt and giant increase of magnetization is observed at a characteristic temperature in the temperature dependence of magnetization curve. These results are discussed in terms of coupling between magnetism and ferroelectric domains including macro- and microdomains for different ferroelectric phases. This work is helpful for understanding the phenomena of electric-field control of magnetism in FM/FE multiferroic heterostructures and is also important for applications.

  1. Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

    Directory of Open Access Journals (Sweden)

    Ambreen Nisar

    2017-07-01

    Full Text Available The refractory diborides (HfB2 and ZrB2 are considered as promising ultra-high temperature ceramic (UHTCs where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness. The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment surpassing that of the parent materials (ZrB2/HfB2-SiC is attributed to the synergy of solid solution formation and enhanced densification (~99.5%. In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications.

  2. Degradation of superconducting Nb/NbN films by atmospheric oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Wolfley, Steven L.; Young, Travis Ryan; Monson, Todd; Pearce, Charles Joseph; Lewis, Rupert M.; Clark, Blythe; Brunke, Lyle Brent; Missert, Nancy A.

    2017-03-01

    Niobium and niobium nitride thin films are transitioning from fundamental research toward wafer scale manufacturing with technology drivers that include superconducting circuits and electronics, optical single photon detectors, logic, and memory. Successful microfabrication requires precise control over the properties of sputtered superconducting films, including oxidation. Previous work has demonstrated the mechanism in oxidation of Nb and how film structure could have deleterious effects upon the superconducting properties. This study provides an examination of atmospheric oxidation of NbN films. By examination of the room temperature sheet resistance of NbN bulk oxidation was identified and confirmed by secondary ion mass spectrometry. As a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.

  3. Exchange interactions and the state of iron atoms in Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ}

    Energy Technology Data Exchange (ETDEWEB)

    Chezhina, N.V., E-mail: chezhina@nc2490.spb.edu [St. Petersburg State University, 7/9 Universitetskaya Nab., 199034 (Russian Federation); Korolev, D.A. [St. Petersburg State University, 7/9 Universitetskaya Nab., 199034 (Russian Federation); Zhuk, N.A. [Syktyvkar State University (Russian Federation); Lutoev, V.P.; Makeev, B.A. [Institute of Geology Komi Scientific Center of Ural branch of Russian Academy of Sciences, Syktyvkar (Russian Federation)

    2017-03-15

    On the basis of the results of magnetic susceptibility and ESR studies of the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions iron atoms in the solid solutions of cubic modification of bismuth niobate were found to exist as Fe(III) monomers and exchange bound Fe(III)-O-Fe(III) dimers with antiferro- and ferromagnetic type of superexchange. The exchange parameters and the distribution of monomers and dimers in the solid solutions were calculated as a function of paramagnetic atom content. - Graphical abstract: The study of the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions showed that the introduction of iron atoms into the structure of Bi{sub 3}NbO{sub 7} stabilizes the cubic structure of bismuth niobate making the phase transition tetragonal ↔ cubic structure irreversible. In the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions we observe the formation of dimers with antiferro- and ferromagnetic exchange. Such clusters are partially retained even at the infinite dilution of the solid solution, which testifies for their rigidity. A sufficiently high parameter of ferromagnetic exchange in a dimer (+53 cm{sup −1}) seems to result from iron atoms being located in the vicinity of oxygen vacancy. - Highlights: • The reversible transition cubic – tetragonal modifications in Bi{sub 3}NbO{sub 7} becomes irreversible. • Only cubic modification of Bi{sub 3}Nb{sub 1-x}Fe{sub x}O{sub 7-δ} is stable due to clusters of Fe atoms. • These clusters are sufficiently strong and retained even at the infinite dilution. • The calculations of magnetic susceptibility give the distribution of the clusters and single atoms.

  4. Electrochemical etching of a niobium foil in methanolic HF for electrolytic capacitor

    International Nuclear Information System (INIS)

    Kim, Kyungmin; Park, Jiyoung; Cha, Gihoon; Yoo, Jeong Eun; Choi, Jinsub

    2013-01-01

    Electrochemical etching of niobium foil in order to enlarge the surface area for the application in electrolytic capacitor was carried out in a methanolic electrolyte. We found that the pit density and depth are not linearly proportional to concentration of HF and applied potential: there is the optimal concentration of HF at each applied potential. The optimal etching condition was obtained at 50 V in 0.99 vol.% HF, which exhibited the capacitance of 350 μF cm −2 . Pit density and depth of pits on electrochemical etched Nb foil under different conditions were counted from SEM images and electrochemical impedance spectroscopy (EIS) of the etched Nb foils was carried out for the capacitance measurement. Equivalent circuit model showing less than 5% error was suggested for applying to the etched niobium foil. - Highlights: • Surface enlargement of Nb foil can be achieved by electrochemical etching in methanolic HF. • Electrolytic capacitor of etched niobium foil exhibits a capacitance of 350 μF cm −2 . • The method provides a way of developing commercially viable process

  5. Relation between time-temperature transformation and continuous heating transformation diagrams of metallic glassy alloys

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.; Inoue, Akihisa

    2005-01-01

    The time-temperature transformation (TTT) diagrams for the onset of devitrification of the Ge-Ni-La and Cu-Hf-Ti glassy alloys were calculated from the isothermal differential calorimetry data using an Arrhenius equation. The continuous heating transformation (CHT) diagrams for the onset of devitrification of the glassy alloys were subsequently recalculated from TTT diagrams. The recalculation method used for conversion of the TTT into CHT diagrams produces reasonable results and is not sensitive to the type of the devitrification reaction (polymorphous or primary transformation). The diagrams allow to perform a comparison of the stabilities of glassy alloys on a long-term scale. The relationship between these diagrams is discussed

  6. Electron microscopy investigations of rapidly solidified Fe-Zr-B-Cu alloys

    International Nuclear Information System (INIS)

    Majumdar, B.; Arvindha Babu, D.; Akhtar, D.

    2010-01-01

    Rapidly solidified Fe-based nanocrystalline soft magnetic materials possess a unique combination of properties i,e high permeability, saturation and Curie temperature and very low coercivity which are otherwise not attainable in conventional soft magnetic materials. The alloys are processed by producing amorphous phase through melt spinning route followed by a partial devitrification for incorporation of nanocrystalline phase in the amorphous matrix. In this paper, detailed electron microscopic investigations of melt spun Fe-Zr-B-Cu alloys are presented. Melt spun ribbons of Fe 99-x-y Zr x BCu 1 alloys with x+y = 11 and x+y = 13 were prepared under different wheel speed conditions and then vacuum annealed for 1 h at different temperatures. The microstructure changes from completely amorphous to a cellular/dendritic bcc solid solution coexisting with the amorphous phase at intercellular/dendritic regions when Zr/B ratio or the process parameters are varied. Annealing leads to the precipitation of nanocrystalline bcc-Fe phase from both amorphous phase and already existing bcc solid solution. (author)

  7. Phase transition temperature in the Zr-rich corner of Zr-Nb-Sn-Fe alloys

    Science.gov (United States)

    Canay, M.; Danón, C. A.; Arias, D.

    2000-08-01

    The influence of small composition changes on the phase transformation temperature of Zr-1Nb-1Sn-0.2(0.7)Fe alloys was studied in the present work, by electrical resistivity measurements and metallographic techniques. For the alloy with 0.2 at.% Fe we have determined Tα↔α+β=741°C and Tα+β↔β=973°C, and for the 0.7 at.% Fe the transformation temperatures were T α↔α+β=712°C and T α+β↔β=961°C. We have verified that the addition of Sn stabilized the β phase.

  8. Mecano-synthesis of the alloy 25%Fe-50%Cu-25%Nb

    International Nuclear Information System (INIS)

    Sousa, Keytiane; Oliveira, Michel Picanco de; Guimaraes, Renan da Silva; Moreira Junior, Valdenir; Filgueira, Marcello

    2016-01-01

    In general, this study aims at the application of mechanical grinding to the system 25% Fe-50% Cu-25% Nb and studies the production process of these powders during milling. The evolution of the structure during the synthesis and the effect of variation of the grinding time were studied by diffraction of X-rays (XRD) and Scanning Electron Microscopy coupled EDS (SEM + EDS) in order to obtain the sizes of crystallites, the phase formation and its evolution with grinding time, and also the homogeneity of the mixture. The particle size distribution was analyzed by laser sedigraph technique. The powders synthesis were performed for milling time of 2.5, 5 and 10 hours. The mechanical grinding showed to be effective with the solid solution formation in the early grinding times. The XRD showed the solid solution formation with subsequent reduction and disappearance of Cu peaks. Through the technique of laser sedigraph it was observed the increase of the particle size followed by the its reduction in the milling time of 10h, a fact that characterizes the mechanical grinding process for ductile powder particles. Thus, the study demonstrated the effectiveness of the mechanical grinding to obtain powder of Fe-Cu-Nb and further processing and application of diamond cutting tools. (author)

  9. High-aspect-ratio HfC nanobelts accompanied by HfC nanowires: Synthesis, characterization and field emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Song, E-mail: tiansong22@126.com [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Li, Hejun, E-mail: lihejun@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China)

    2017-04-30

    Highlights: • HfC naobelts accompanied by HfC nanowires were synthesized by a catalytic CVD method. • HfC nanobelts as a novel structure of HfC ceramic are reported for the first time. • HfC nanobelts have 100–200 μm in lengths and reach up to 10 μm in widths. • The synthesized product is promising field nanoemitters. - Abstract: As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor–liquid–solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO{sub 2} shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm{sup −1} and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications.

  10. Influence of the fabrication conditions on the high frequency magnetic response of melt spun Fe73.5Si13.5B9Nb3Cu1

    International Nuclear Information System (INIS)

    Pascual, L.; El Ghannami, M.; Vazquez, M.; Gomez-Polo, C.; Univ. Publica de Navarra, Pamplona

    1998-01-01

    The aim of this work is to analyze the influence of the fabrication conditions on the magnetic properties of Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 melt-spun nanocrystalline ribbons. Different initial structures, amorphous and partially crystalline, have been obtained during the rapid solidification procedure. The structural characterization shows that a decrease in the quenching rate through a reduction in the tangential wheel velocity, gives rise to a partially crystalline state, characterized by the appearance of a textured α-FeSi nanocrystalline phase. The occurrence of the crystalline fraction in the initial as-cast state gives rise to a magnetic hardening with respect to the amorphous sample casted at higher quenching rate. However, the evolution of coercivity under thermal treatments is roughly independent of the initial structure. Moreover, a detailed analysis of the ac susceptibility as a function of annealing temperature shows that the ribbon obtained at lower quenching rate presents higher susceptibility values in the optimum magnetic state (T a = 550 C. 1 h) in a wide range of driving frequency (up to 100 kHz). (orig.)

  11. Microstructure and property of Fe–Co–B–Si–C–Nb amorphous composite coating fabricated by laser cladding process

    International Nuclear Information System (INIS)

    Zhu, Y.Y.; Li, Z.G.; Li, R.F.; Li, M.; Daze, X.L.; Feng, K.; Wu, Y.X.

    2013-01-01

    Laser cladding of Fe 34 Co 34 B 20 Si 5 C 3 Nb 4 on a low carbon steel substrate was conducted using coaxial powder feeding method. Microstructure, phase and microhardness were investigated by scanning electronic microscopy, transmission electron microscopy, X-ray diffraction, electron probe micro-analysis and microhardness tester. Amorphous coating with NbC particles embedded in the matrix was formed. Differential scanning calorimetry curve showed that the glass transition temperature (T g ) and the onset crystallization temperature (T x ) were 799 K and 850 K, respectively. The supercooled liquid region (ΔT x = T x − T g ) was as large as 51 K, which implied the high thermal stability of the supercooled liquid against crystallization. Due to the NbC particles embedded in the amorphous matrix, the mean value of the microhardness of the coating prepared by laser cladding was higher than that of the bulk metallic glass formed by the copper mold casting method. The contribution of NbC particles to the total microhardness was theoretically estimated. The estimated hardness of the composite coating agreed well with the tested value.

  12. Interface-driven alloying and metallic glass formation in nano-multilayers in an immiscible Y-Nb system

    International Nuclear Information System (INIS)

    Chen, Y.G.; Liu, B.X.; Nanjing Univ.

    1999-01-01

    Several new amorphous alloys were obtained in an immiscible Y-Nb system by room temperature 190 keV xenon ion mixing of Y-Nb multilayered films, which were designed to include a sufficient fraction of interfacial atoms and thus possessed a high free energy comparable to that of the amorphous state. In addition, two metastable f.c.c. phases were formed in Y-rich and Nb-rich multilayered films, respectively. The growth kinetics of the f.c.c. phases and their effect on the composition range of amorphization are also discussed. To understand the observed unusual alloying behaviors, a Gibbs free-energy diagram was constructed based on Miedema's model. The diagram included the free-energy curves of all the involved phases as well as that of the Y-Nb multilayered films including the extra interfacial free energy and thus gave a qualitative and reasonable interpretation to the formation of metastable alloys upon ion mixing. Furthermore, some multilayered films with a sufficient fraction of interfacial atoms were subjected to steady-state thermal annealing, which also resulted in the formation of the Y-Nb amorphous phases, suggesting that alloying in this immiscible system was actually driven by the interfacial free energy

  13. Atomic force microscope and scanning tunneling microscope studies of superlattices and density waves in Fe doped NbSe2, TaSe2, TaS2 and in NbSe3 doped with Fe, Co, Cr, and V

    International Nuclear Information System (INIS)

    Coleman, R.V.; Dai, Z.; Gong, Y.; Slough, C.G.; Xue, Q.

    1994-01-01

    Results of atomic force microscope (AFM) and scanning tunneling microscope (STM) studies of superlattices and long-range modulations induced by impurities in transition metal chalcogenides are presented. Superlattices formed by Fe intercalation into the van der Waals gaps of 2H--NbSe 2 , 2H--TaSe 2 and 2H--TaS 2 show ordered occupation of the octahedral holes and STM spectroscopy shows density-wave energy gaps existing in the antiferromagnetic phases. In NbSe 3 , interstitial impurities such as Fe, Co, Cr, and V induce long-range modulated structures that can be detected at room temperature with AFM scans. These modulations modify the charge-density wave structure forming at low temperature and STM spectroscopy has been used to measure these changes

  14. Electron-irradiation induced changes in structural and magnetic properties of Fe and Co based metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kane, S.N., E-mail: kane_sn@yahoo.com [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Satalkar, M., E-mail: satalkar.manvi@gmail.com [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Ghosh, A.; Shah, M. [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Ghodke, N. [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001 (India); Pramod, R.; Sinha, A.K.; Singh, M.N.; Dwivedi, J. [Raja Ramanna Centre for Advanced Technology, P.O. CAT, Indore 452013 (India); Coisson, M.; Celegato, F.; Vinai, F.; Tiberto, P. [INRIM, Electromagnetism Division, Strada Delle Cacce 91, I-10135 TO (Italy); Varga, L.K. [RISSPO, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary)

    2014-12-05

    Highlights: • Enhancement of Ms by low electron irradiation dose in Fe-based alloy. • Variation of magnetic properties by electron irradiation induced ordered phase. • Electron irradiation alters TM-TM distance and, magnetic properties. - Abstract: Electron-irradiation induced changes in structural and, magnetic properties of Co{sub 57.6}Fe{sub 14.4}Si{sub 4.8}B{sub 19.2}Nb{sub 4}, Fe{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4} and, Co{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4} metallic glasses were studied using magnetic hysteresis and, synchrotron X-ray diffraction measurements. Results reveal composition dependent changes of magnetic properties in electron irradiated metallic glasses. A low electron irradiation dose (15 kGy) enhances saturation magnetization (up to 62%) in Fe-based alloy (Fe{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4}). Synchrotron XRD measurements reveal that electron irradiation transforms the amorphous matrix to a more ordered phase, accountable for changes in magnetic properties.

  15. Investigation of Mn Implanted LiNbO3 applying electron paramagnetic resonance technique

    International Nuclear Information System (INIS)

    Darwish, A.; Ila, D.; Poker, D.B.; Hensley, D.K.

    1997-10-01

    The effect of ion implantation on the LiNbO 3 crystal is studied using electron paramagnetic resonance spectroscopy (EPR). EPR measurements on these crystals were performed as a function of ion species Mn and Fe and fluence at room temperature. Also the effect of the laser illumination on the EPR signal was determined by illuminating the crystal in situ and measuring the decay and growth of the EPR signal. LiNbO 3 :Mn 2+ at a depth of approximately 200 nm was formed by implantation of 2.5 x 10 14 Mncm 2 and 1 x 10 17 Mn/cm 2 at 2 MeV. The implanted samples were compared with bulk doped crystals. It was found that the decay and growth of Mn EPR for the implanted crystal is very small compared with the bulk doped LiNbO 3 :Mn crystal. This was found to be primarily due to the spin concentration on the crystals. On the other, hand the decay time of the high fluence is about 40% slower than the decay of the low fluence implanted crystal

  16. Structure, chemistry and luminescence properties of dielectric La{sub x}Hf{sub 1-x}O{sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Kaichev, V.V., E-mail: vvk@catalysis.ru [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Smirnova, T.P.; Yakovkina, L.V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation); Ivanova, E.V.; Zamoryanskaya, M.V. [Ioffe Physical-Technical Institute, St. Petersburg (Russian Federation); Saraev, A.A. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Pustovarov, V.A. [Ural State Technical University, Ekaterinburg (Russian Federation); Perevalov, T.V.; Gritsenko, V.A. [Novosibirsk State University, Novosibirsk (Russian Federation); Rzhanov Institute of Semiconductor Physics, Novosibirsk (Russian Federation)

    2016-06-01

    Dielectric films of La{sub 2}O{sub 3}, HfO{sub 2}, and La{sub x}Hf{sub 1-x}O{sub y} were synthesized by metal-organic chemical vapor deposition. Structural, chemical, and luminescence properties of the films were studied using X-ray photoelectron spectroscopy, methods of X-ray diffraction and selected area electron diffraction, high-resolution transmission electron microscopy, and a cathodoluminescence technique. It was found that doping of hafnium oxide with lanthanum leads to the formation of a continuous series of solid solutions with a cubic structure. This process is accompanied by the formation of oxygen vacancies in the HfO{sub 2} lattice. Cathodoluminescence spectra of the La{sub x}Hf{sub 1-x}O{sub y}/Si films exhibited a wide band with the maximum near 2.4–2.5 eV, which corresponds to the blue emission. Quantum-chemical calculations showed that this blue band is due to oxygen vacancies in the HfO{sub 2} lattice. - Highlights: • HfO{sub 2} and solid solution La{sub x}Hf{sub 1-x}O{sub y} films were synthesized by MOCVD. • The continuous series of solid solutions with a cubic structure was formed at La doping of HfO{sub 2}. • Cathodoluminescence band at 2.4–2.5 eV is observed due to the oxygen vacancies in La{sub x}Hf{sub 1-x}O{sub y}. • The cathodoluminescence decreases in intensity when the La concentration increases.

  17. Orbital physics in sulfur spinels: ordered, liquid and glassy ground states

    International Nuclear Information System (INIS)

    Buettgen, N; Hemberger, J; Fritsch, V; Krimmel, A; Muecksch, M; Nidda, H-A Krug von; Lunkenheimer, P; Fichtl, R; Tsurkan, V; Loidl, A

    2004-01-01

    Measurements of magnetization M(T, H), heat capacity C(T), NMR lineshift K(T) and linewidth Δ(T), neutron scattering S(Q, ω, T) and broadband dielectric spectroscopy ε(ω, T) provide experimental evidence of the different orbital ground states in the cubic sulfur spinels under investigation. In all compounds, the tetrahedrally coordinated Jahn-Teller ions Fe 2+ are characterized by a degeneracy of the orbital degrees of freedom. Particularly, we found a long-range orbital ordering in polycrystalline (PC) FeCr 2 S 4 , and a glassy freezing of the orbital degrees of freedom in FeCr 2 S 4 (single crystals) (SCs). In contrast, FeSc 2 S 4 belongs to the rare class of spin-orbital liquids, where quantum fluctuations accompanying the glassy freezing of the orbitals suppress long-range magnetic order

  18. Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dapeng; Poudyal, Narayan; Rong, Chuanbing; Zhang, Ying; Kramer, Matthew J.; Liu, J. Ping

    2012-05-11

    Nanoscalehybridmagnets containing SmCo5 and Nd2Fe14B hard magnetic phases have been produced via a novel “in-one-pot” processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybridmagnets have greatly improved thermal stability compared to the Nd2Fe14B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo5 counterpart.

  19. Ti-catalyzed HfSiO4 formation in HfTiO4 films on SiO2 studied by Z-contrast scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Elizabeth Ellen Hoppe

    2013-08-01

    Full Text Available Hafnon (HfSiO4 as it is initially formed in a partially demixed film of hafnium titanate (HfTiO4 on fused SiO2 is studied by atomic number (Z contrast high resolution scanning electron microscopy, x-ray diffraction, and Raman spectroscopy and microscopy. The results show exsoluted Ti is the catalyst for hafnon formation by a two-step reaction. Ti first reacts with SiO2 to produce a glassy Ti-silicate. Ti is then replaced by Hf in the silicate to produce HfSiO4. The results suggest this behavior is prototypical of other Ti-bearing ternary or higher order oxide films on SiO2 when film thermal instability involves Ti exsolution.

  20. 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.

  1. An electrochemical sensor for rizatriptan benzoate determination using Fe3O4 nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples.

    Science.gov (United States)

    Madrakian, Tayyebeh; Maleki, Somayeh; Heidari, Mozhgan; Afkhami, Abbas

    2016-06-01

    In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles (Fe3O4/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe3O4 nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5-100.0 μmol L(-1) with a detection limit of 0.09 μmol L(-1) under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Microstructural comparison of effects of hafnium and titanium additions in spark-plasma-sintered Fe-based oxide-dispersion strengthened alloys

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yina, E-mail: huangyina1981@hotmail.com [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Hongtao [Department of Materials, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Auger, Maria A.; Hong, Zuliang [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Ning, Huanpo [School of Engineering of Materials Science, Queen Mary University of London, London, E1 4NS (United Kingdom); Nanoforce Technology Ltd, London, E1 4NS (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Grant, Patrick S. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Reece, Michael J.; Yan, Haixue [School of Engineering of Materials Science, Queen Mary University of London, London, E1 4NS (United Kingdom); Nanoforce Technology Ltd, London, E1 4NS (United Kingdom); Roberts, Steve G. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom)

    2017-04-15

    Two oxide dispersion strengthened alloys: 14Cr-0.25Y{sub 2}O{sub 3}-0.22Hf (wt.%) and Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.4Ti (wt.%) were fabricated by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS). Electron backscatter diffraction showed grain sizes in the range 0.5–15 μm in both alloys. Transmission electron microscopy and scanning transmission electron microscopy showed a homogeneous distribution of nano-oxides precipitated during SPS. Using high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and atom probe tomography, several different oxide phases were found in both alloys, but the majority of dispersoids were Y-Hf-O type in Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.22Hf and Y-Ti-O type in Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.4Ti. There were a variety of orientation relationships between the different dispersoids and the ferritic matrix. Both alloys had dispersoid densities of ∼10{sup 23}/m{sup 3}, with average diameters of 4.3 nm and 3.5 nm in the 0.22Hf and 0.4Ti containing alloys, respectively. Per atom added, Hf (0.07 at.%) is suggested to be more potent than Ti (0.46 at.%) in refining the nano-oxides.

  3. Hf-Nd isotope constraints on the origin of the Cretaceous Caribbean plateau and its relationship to the Galápagos plume

    Science.gov (United States)

    Thompson, P. M. E.; Kempton, P. D.; White, R. V.; Kerr, A. C.; Tarney, J.; Saunders, A. D.; Fitton, J. G.; McBirney, A.

    2004-01-01

    Formation of the Cretaceous Caribbean plateau, including the komatiites of Gorgona, has been linked to the currently active Galápagos hotspot. We use Hf-Nd isotopes and trace element data to characterise both the Caribbean plateau and the Galápagos hotspot, and to investigate the relationship between them. Four geochemical components are identified in the Galápagos mantle plume: two 'enriched' components with ɛHf and ɛNd similar to enriched components observed in other mantle plumes, one moderately enriched component with high Nb/Y, and a fourth component which most likely represents depleted MORB source mantle. The Caribbean plateau basalt data form a linear array in Hf-Nd isotope space, consistent with mixing between two mantle components. Combined Hf-Nd-Pb-Sr-He isotope and trace element data from this study and the literature suggest that the more enriched Caribbean end member corresponds to one or both of the enriched components identified on Galápagos. Likewise, the depleted end member of the array is geochemically indistinguishable from MORB and corresponds to the depleted component of the Galápagos system. Enriched basalts from Gorgona partially overlap with the Caribbean plateau array in ɛHf vs. ɛNd, whereas depleted basalts, picrites and komatiites from Gorgona have a high ɛHf for a given ɛNd, defining a high- ɛHf depleted end member that is not observed elsewhere within the Caribbean plateau sequences. This component is similar, however, in terms of Hf-Nd-Pb-He isotopes and trace elements to the depleted plume component recognised in basalts from Iceland and along the Reykjanes Ridge. We suggest that the Caribbean plateau represents the initial outpourings of the ancestral Galápagos plume. Absence of a moderately enriched, high Nb/Y component in the older Caribbean plateau (but found today on the island of Floreana) is either due to changing source compositions of the plume over its 90 Ma history, or is an artifact of limited sampling. The

  4. Effects of annealing, acid and alcoholic beverages on Fe1+yTe0.6Se0.4

    International Nuclear Information System (INIS)

    Sun, Y; Taen, T; Tsuchiya, Y; Tamegai, T; Shi, Z X

    2013-01-01

    We have systematically investigated and compared different methods to induce superconductivity in the iron chalcogenide Fe 1+y Te 0.6 Se 0.4 , including annealing in a vacuum, N 2 , O 2 and I 2 atmospheres and immersing samples into acid and alcoholic beverages. Vacuum and N 2 annealing are proved to be ineffective in inducing superconductivity in a Fe 1+y Te 0.6 Se 0.4 single crystal. Annealing in O 2 and I 2 and immersion in acid and alcoholic beverages can induce superconductivity by oxidizing the excess Fe in the sample. Superconductivity in O 2 annealed samples is of a bulk nature, while I 2 , acid and alcoholic beverages can only induce superconductivity near the surface. By comparing the different effects of O 2 , I 2 , acid and alcoholic beverages we propose a scenario to explain how the superconductivity is induced in the non-superconducting as-grown Fe 1+y Te 0.6 Se 0.4 . (paper)

  5. The improved magnetic properties in phosphorus substituted Pr-Fe-P-B nanocomposites

    International Nuclear Information System (INIS)

    Jin, Z.Q.; Zhang, Y.; Wang, H.L.; Klaessig, A.; Bonder, M.; Hadjipanayis, G.C.

    2003-01-01

    Phosphorus substituted (Pr,Tb) 8 (Fe,Nb,Zr,P) 88 B 4 nanocomposites have been produced by melt-spinning. The effects of phosphorus substitution as well as wheel speed on the crystallization behavior and magnetic properties of the melt-spun samples have been investigated. With the substitution of phosphorus, the crystallization temperature of amorphous phase increases. The optimum wheel speed was found to be around 25 m/s for as-spun ribbons and 40 m/s for the annealed samples, both of which present excellent second quadrant hysteresis loop shapes due to the fine grain size of α-Fe which is around 20 nm. The addition of phosphorus also greatly improves the coercivity of Pr-Fe-B nanocomposites without a significant loss of saturation magnetization. A higher coercivi