WorldWideScience

Sample records for fe-base amorphous alloys

  1. 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

  2. Wear behaviors of a Fe-based amorphous alloy in ambient atmosphere and in distilled water

    Science.gov (United States)

    Jang, B. T.; Kim, S. S.; Yi, S.

    2014-01-01

    Wear behaviors of a Fe-based bulk amorphous alloy with more 3MPa yield strength against AISI 304 disc were studied in different environment using a unidirectional tribometer. Friction behaviors were also investigated in the state of both amorphous pin on amorphous disc test set and the amorphous pin on AISI 304 disc test set with surface temperature using thermocouple embedded pin. Wear mechanisms of a Fe-based bulk amorphous alloy have been proposed based upon the microstructural analysis and surface temperature measurements during pin-on disc friction tests in ambient atmosphere and in distilled water, respectively. Delamination from the smooth friction surface was the main wear mechanism during the friction test in ambient atmosphere, while brittle fracture morphologies were apparent on the friction surface formed in a distilled water condition. Based upon the surface temperature measurements, difference in the heat removal efficiency on the friction surface due to different atmospheres was suggested to cause distinct wear mechanisms.

  3. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2010-07-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  4. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    International Nuclear Information System (INIS)

    Cabral P, A.; Garcia S, I.; Contreras V, J. A.; Garcia S, F.; Nava, N.

    2010-01-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  5. Effect of Co content on structure and magnetic behaviors of high induction Fe-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Rajat K., E-mail: rajat@nmlindia.org; Panda, Ashis K.; Mitra, Amitava

    2016-11-15

    The replacement of Fe with Co is investigated in the (Fe{sub 1−x}Co{sub x}){sub 79}Si{sub 8.5}B{sub 8.5}Nb{sub 3}Cu{sub 1} (x=0, 0.05, 0.2, 0.35, 0.5) amorphous alloys. The alloys are synthesized in the forms of ribbons by single roller melt spinning technique, and the structural and magnetic properties of annealed ribbons are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), B–H curve tracer, respectively. All as-cast alloys are structurally amorphous, however, their magnetic properties are varying with Co addition. The Co addition within 5–20 at% results in moderate thermal stability, saturation induction, Curie temperature and lowest coercivity, while 35 at% Co causes highest saturation induction, coercivity, Curie temperature and lowest thermal stability. On devitrification, the magnetic properties change with the generation of α-FeCo nanocrystallites and (FeCo){sub 23}B{sub 6}, Fe{sub 2}B phases during primary and secondary crystallization stages, respectively. A small amount Co is advantageous for maintaining finer nanocrystallites in amorphous matrix even after annealing at 600 °C, leading to high saturation magnetization (>1.5 T) and low coercivity (~35 A/m). The improved magnetic properties at elevated temperatures indicate these alloys have a potential for high frequency transformer core applications. - Highlights: • The structural and magnetic behaviors of Fe based amorphous alloys have been investigated with the effect of Co content. • The Co has no adverse effect on amorphization of alloys. • A small amount Co causes the superior improvement of magnetic properties at elevated temperatures. • Therefore, it is important not only for academic research but also for industrial applied research.

  6. Pulsed laser deposition of magnetic films by ablation of Co- and Fe-based amorphous alloys

    Czech Academy of Sciences Publication Activity Database

    Caricato, A. P.; Frenández, M.; Frait, Zdeněk; Fraitová, Dagmar; Luby, S.; Luches, A.; Majková, E.; Majni, G.; Malych, Rastislav; Mengucci, P.

    2004-01-01

    Roč. 79, - (2004), s. 1251-1254 ISSN 0947-8396 Grant - others:VEGA(SK) 2/1106/22; VEGA(SK) 2/3149/23; MIUR(IT) Cluster P10-B; HPRN-CT(XE) 1999-00150 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic resonance * thin amorphous films * magnetization damping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.452, year: 2004

  7. Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

    Science.gov (United States)

    Skulkina, N. A.; Ivanov, O. A.; Pavlova, I. O.; Minina, O. A.

    2011-12-01

    On the example of soft magnetic Fe81B13Si4C2 and Fe77Ni1Si9B13 amorphous alloys, the relation between the level of magnetic properties and duration of isothermal holding in the course of heat treatment in air has been studied. The optimum temperature-dependent time τ of isothermal holding has been shown to be related to the volume fraction of domains ( V orth) with orthogonal magnetization in the initial (quenched) ribbon by equation V orth = ττ1/3. A temperature dependence of the proportionality coefficient α, which determines the degree of diffusion-process activity, has been determined. The results obtained allow us to substantially simplify the choice of optimum conditions of atmospheric heat treatment of soft magnetic Fe-based amorphous ribbons.

  8. Microstructure evolution and thermal stability of an Fe-based amorphous alloy powder and thermally sprayed coatings

    International Nuclear Information System (INIS)

    Chokethawai, K.; McCartney, D.G.; Shipway, P.H.

    2009-01-01

    High velocity oxy-fuel (HVOF) thermal spraying has been used to produce coatings of an Fe-18.9%Cr-16.1%B-4.0%C-2.8%Si-2.4%Mo-1.9%Mn-1.7%W (in at.%) alloy from a commercially available powder (Nanosteel SHS7170). X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to investigate the powder, as-sprayed coatings and annealed coatings which had been heated to temperatures in the range of 550-925 deg. C for times ranging from 60 to 3900 min. Microhardness changes of the coatings were also measured as a function of annealing time and temperature. The powder was found to comprise amorphous and crystalline particles; the former had a maximum diameter of around 22 μm. The coating was composed of splat like regions, arising from rapid solidification of fully molten powder, and near-spherical regions from partially melted powder which had a largely retained its microstructure. The amorphous fraction of the coating was around 50% compared with 18% for the powder. The enthalpies and activation energies for crystallization of the amorphous phase were determined. Crystallization occurred in a two stage process leading to the formation of α-Fe (bcc), Fe 1.1 Cr 0.9 B 0.9 and M 23 C 6 phases. DSC measurements showed that the first stage occurred at 650 deg. C. Annealing the coating gave a hardening response which depended on temperature and time. The as-sprayed coating had a hardness of 9.2 GPa and peak hardnesses of 12.5 and 11.8 GPa were obtained at 650 and 750 deg. C, respectively. With longer annealing times hardness decreased rapidly from the peak.

  9. Mixed hyperfine interaction - a tool to investigate the short range order and the strange magnetic behaviour of amorphous Fe-based binary alloys

    International Nuclear Information System (INIS)

    Fries, S.M.; Crummenauer, J.; Gonser, U.; Schaaf, P.; Chien, C.L.

    1989-01-01

    The Moessbauer study of the mixed magnetic dipole and electric quadrupole interaction in the paramagnetic state of amorphous Fe-Zr and Fe-Hf alloys is presented. Strong evidence for chemical short range order of the iron-pure alloys is found. The hyperfine parameters of the iron-rich alloys are marked by a complex applied field and temperature dependence, suggesting a not negligible spin-correlation well above Tc. (orig.)

  10. Kinetics of crystallization of a Fe-based multicomponent amorphous ...

    Indian Academy of Sciences (India)

    Administrator

    these amorphous alloys, which consequently led to better magnetic performance (Yoshizawa 1988). The kinetics of crystallization plays an important role in physics, chemistry, ceramic and metallurgical sciences. Thermal analysis methods, including DSC, are exten- sively used for studying kinetics of chemical reactions.

  11. Poor glass-forming ability of Fe-based alloys

    DEFF Research Database (Denmark)

    Zheng, H.J.; Hu, L.N.; Zhao, X.

    2017-01-01

    processes. By using the concept of fluid cluster and supercooled liquid fragility in metallic liquids, it has been found that this dynamic transition makes the Fe-based supercooled liquids become more unstable, which leads to the poor GFA of Fe-based alloys. Further, it has been found that the degree...

  12. Thermal Conductivity and Wear Behavior of HVOF-Sprayed Fe-Based Amorphous Coatings

    Directory of Open Access Journals (Sweden)

    Haihua Yao

    2017-10-01

    Full Text Available To protect aluminum parts in vehicle engines, metal-based thermal barrier coatings in the form of Fe59Cr12Nb5B20Si4 amorphous coatings were prepared by high velocity oxygen fuel (HVOF spraying under two different conditions. The microstructure, thermal transport behavior, and wear behavior of the coatings were characterized simultaneously. As a result, this alloy shows high process robustness during spraying. Both Fe-based coatings present dense, layered structure with porosities below 0.9%. Due to higher amorphous phase content, the coating H-1 exhibits a relatively low thermal conductivity, reaching 2.66 W/(m·K, two times lower than the reference stainless steel coating (5.85 W/(m·K, indicating a good thermal barrier property. Meanwhile, the thermal diffusivity of amorphous coatings display a limited increase with temperature up to 500 °C, which guarantees a steady and wide usage on aluminum alloy. Furthermore, the amorphous coating shows better wear resistance compared to high carbon martensitic GCr15 steel at different temperatures. The increased temperature accelerating the tribological reaction, leads to the friction coefficient and wear rate of coating increasing at 200 °C and decreasing at 400 °C.

  13. FE-based long range ordered alloys

    International Nuclear Information System (INIS)

    Liu, C.-T.; Inouye, H.; Schaffhauser, A.C.

    1981-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Co,Fe) 3 and V(Co,Fe,Ni) 3 system having a specified composition with an electron density no greater than 8.00. Excellent high temperature properties occur in alloys in this system, having specified compositions. The alloys are fabricable by casting, deforming and annealing for sufficient time to provide ordered structure. (author)

  14. Amorphous Semiconductor Alloys

    Science.gov (United States)

    Madan, Arun

    1985-08-01

    Amorphous silicon (a-Si) based alloys have attracted a considerable amount of interest because of their applications in a wide variety of technologies. However, the major effort has concentrated on inexpensive photovoltaic device applications and has moved from a laboratory curiosity in the early 1970's to viable commercial applications in the 1980's. Impressive progress in this field has been made since the group at University of Dundee demonstrated that a low defect, device quality hydrogenated amorphous silicon (a-Si:H) 12 material could be produced using the radio frequency (r.f.) glow discharge in SiH4 gas ' and that the material could be doped n- and p-type.3 These results spurred a worldwide interest in a-Si based alloys, especially for photovoltaic devices which has resulted in a conversion efficiency approaching 12%. There is now a quest for even higher conversion efficiencies by using the multijunction cell approach. This necessitates the synthesis of new materials of differing bandgaps, which in principle amorphous semiconductors can achieve. In this article, we review some of this work and consider from a device and a materials point of view the hurdles which have to be overcome before this type of concept can be realized.

  15. Acoustic properties of TiNiMoFe base alloys

    International Nuclear Information System (INIS)

    Gyunter, V.Eh.; Chernyshev, V.I.; Chekalkin, T.L.

    2000-01-01

    The regularity of changing the acoustic properties of the TiNi base alloys in dependence on the alloy composition and impact temperature is studied. It is shown that the oscillations of the TiNiMoFe base alloys within the temperature range of the B2 phase existence and possible appearance of the martensite under the load differ from the traditional materials oscillations. After excitation of spontaneous oscillations within the range of M f ≤ T ≤ M d there exists the area of long-term and low-amplitude low-frequency acoustic oscillations. It is established that free low-frequency oscillations of the TH-10 alloy sample are characterized by the low damping level in the given temperature range [ru

  16. Prediction of heating rate controlled viscous flow activation energy during spark plasma sintering of amorphous alloy powders

    Science.gov (United States)

    Paul, Tanaji; Harimkar, Sandip P.

    2017-07-01

    The viscous flow behavior of Fe-based amorphous alloy powder during isochronal spark plasma sintering was analyzed under the integrated theoretical background of the Arrhenius and directional structural relaxation models. A relationship between viscous flow activation energy and heating rate was derived. An extension of the pertinent analysis to Ti-based amorphous alloys confirmed the broad applicability of such a relationship for predicting the activation energy for sintering below the glass transition temperature (T g) of the amorphous alloy powders.

  17. Amorphization of equimolar alloys with HCP elements during mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Liang [Materials and Electro-Optics Research Division, Chung-Shan Institute of Science and Technology, Armaments Bureau, MND, P.O. Box 90008-8-5, Lung-Tan, Tao-Yuan 32599, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Tsai, Che-Wei; Juan, Chien-Chang; Chuang, Ming-Hao [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Yeh, Jien-Wei, E-mail: jwyeh@mx.nthu.edu.t [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Chin, Tsung-Shune [Department of Materials Science and Engineering, Feng Chia University, 100, Wenhwa Rd., Seatwen District, Taichung 40724, Taiwan (China); Chen, Swe-Kai [Center for Nanotechnology, Materials Science and Microsystems, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

    2010-09-10

    This study prepares two equimolar alloys, entirely composed of HCP elements, BeCoMgTi and BeCoMgTiZn, from elemental powders by mechanical alloying. No crystalline solid solutions and compounds formed during milling except an amorphous phase formed gradually until full amorphization was attained. The amorphization processes of these two alloys conform to type II according to the Weeber and Bakker classification based on binary alloys. The inhibition of crystalline solid solutions and compounds before amorphization relates to chemical compatibility, high entropy effect and large atomic size difference effect.

  18. Magnetic and Random Anisotropy Studies in some Amorphous Fe-Based Compounds

    Science.gov (United States)

    Tlemçani, Mohamed; Benbachir, Khadija; Sayouri, Salaheddine; Meknassi, K.; Kadiri, H.

    2000-12-01

    We have studied the magnetization of melt spun amorphous Fe100-x-yCrx(PCSi)y alloys with 4≤x≤11 and 19≤y≤22 under magnetic fields up to 18 kOe, and have analyzed the results at 10 K in the framework of the phenomenological model of Chudnovsky and Serota. Behaviour of magnetic moment and exchange and anisotropy constants has been compared to that of the same parameters in amorphous FeNi(BSi), FeNiCr(BSi) and FeV(BSi).

  19. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...... and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  20. Formation of Fe-Nb-X (X=Zr, Ti) amorphous alloys from pure metal elements by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Zhiyu [National Engineering Research Center of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640 (China); Tang Cuiyong, E-mail: hnrtcy@163.com [National Engineering Research Center of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640 (China); Ngai, Tungwai Leo; Yang Chao; Li Yuanyuan [National Engineering Research Center of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640 (China)

    2012-01-15

    Fe-based amorphous powders of Fe{sub 56}Nb{sub 6}Zr{sub 38} and Fe{sub 60}Nb{sub 6}Ti{sub 34} based on binary eutectic were prepared by mechanical alloying starting from mixtures of pure metal powders. The amorphization behavior and thermal stability were examined by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry. Results show that Fe{sub 56}Nb{sub 6}Zr{sub 38} alloy has a better glass forming ability and a relatively lower thermal stability comparing with Fe{sub 60}Nb{sub 6}Ti{sub 34} alloy. The prepared amorphous powders have homogeneous element distribution and no obvious contaminants coming from mechanical alloying. The synthesized amorphous powders offer the potential for consolidation to full density with desirable mechanical properties through the powder metallurgy methods.

  1. Effects of the addition of Co, Ni or Cr on the decolorization properties of Fe-Si-B amorphous alloys

    Science.gov (United States)

    Zhang, Changqin; Zhu, Zhengwang; Zhang, Haifeng

    2017-11-01

    Fe-based amorphous alloys show great potential in degrading azo dyes and other organic pollutants, and are widely investigated as a kind of environmental-friendly materials for wastewater remediation. In this paper, the effects of Co, Ni or Cr addition on the decolorization properties of Fe-Si-B amorphous alloys were studied, and the mechanism of their different effects was analyzed. Co addition could lower the activation energy of Fe-Si-B amorphous alloys in decolorizing azo dyes, and had no weakening effect on the decolorization capability of Fe-Si-B amorphous alloys. Ni addition led to partial crystallization of Fe-Si-B amorphous alloys, and the decolorization mechanism at low temperatures changed from chemical degradation to physical adsorption. Cr addition could enhance the corrosion resistance of Fe-Si-B amorphous alloys, but the amorphous alloys completely lost the decolorization capability no matter at lower or higher temperatures. The results of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that the addition of Co, Ni or Cr could generate different surface structures that had significant influences on the decolorization process. Our work demonstrated that the effiecient decolorization of azo dyes by Fe-based alloys could be realized only when amorphous nature and incompact surface structure were simultaneously achieved for the alloys.

  2. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  3. The welding characteristics of Fe-based shape memory alloys

    International Nuclear Information System (INIS)

    Lin, H.C.; Lin, K.M.; Chuang, Y.C.; Chen, F.H.

    2000-01-01

    After TIG and laser welding, the microstructure, shape memory effect and chemical corrosion resistance of Fe-30Mn-6Si and Fe-30Mn-6Si-5Cr shape memory alloys have been investigated. Experimental results show that the welded zones exhibit dendrite structures. The as-welded alloys still have an excellent shape memory effect. The corrosion resistance of welded zones is found to be worse than that of the base-material for both Fe-30Mn-6Si and Fe-30Mn-6Si-5Cr alloys. The degradation of corrosion resistance is more obvious for laser-welded zone than that for TIG-welded zone. After annealing treatment of 1100 C x 2h for these welded alloys, the dendrite structures in the welded zones disappear and the corrosion resistance is improved. (orig.)

  4. Plasma deposition of amorphous metal alloys

    Science.gov (United States)

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  5. Annealing behavior of high permeability amorphous alloys

    International Nuclear Information System (INIS)

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co 71 4 Fe 4 6 Si 9 6 B 14 4 were investigated. Annealing this alloy below 400 0 C results in magnetic hardening; annealing above 400 0 C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation

  6. Laser assisted Fe-based bulk amorphous coating: Thermal effects and corrosion

    International Nuclear Information System (INIS)

    Katakam, Shravana; Kumar, Vivek; Santhanakrishnan, S.; Rajamure, Ravishankar; Samimi, P.; Dahotre, Narendra B

    2014-01-01

    Highlights: • Volume fraction of the amorphous phase increases with laser energy density. • Improved corrosion resistance of coatings compared to substrate. • Corrosion resistance of coatings decreases with increase in laser energy density. • Significant pitting due to precipitation of carbides for higher laser powers. • Phase transformation explained with the help of thermal modeling results. - Abstract: The present study focuses on synthesizing composite coatings for corrosion resistance using laser surface alloying (LSA). Amorphous powder with nominal composition (Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 ) is used as the precursor powder on AISI 4130 steel substrate and processed with a continuous wave ytterbium Nd-YAG fiber laser. A multi-physics based heat transfer model was developed to evaluate the thermal histories experienced during processing. The thermodynamic parameters like peak temperatures and cooling rates are evaluated using the computational model and correlated to the evolution of microstructure. Phase and microstructural characterization of the coatings was conducted using XRD, SEM and TEM. Anodic polarization tests conducted in HCl medium indicated the enhancement in corrosion resistance of the laser processed samples. The laser processed samples showed better corrosion resistance than the substrate and among the processed samples, the corrosion resistance decreased with increasing laser energy density. The reduction in the corrosion resistance can be attributed to the formation of Cr 23 C 6 nano crystals in the amorphous phase. The operating corrosion mechanisms are discussed with the aid of the thermal modeling results

  7. High frequency magnetic properties of Fe-based nanocrystalline alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.K. [Seoul National University of Technology, Seoul 139-743 (Korea); Korea Institute of Science and Technology, Seoul 136-791 (Korea); Kim, Yoon B.; Jee, K.K. [Korea Institute of Science and Technology, Seoul 136-791 (Korea); Choi, G.B. [R and D Center, Changsung Corporation, Incheon (Korea)

    2007-12-15

    Toroidal shape Fe-based nanocrystalline alloy powder cores were prepared from the melt spun Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} ribbons by cold pressing using silicon and phenol resin as an insulating material, respectively. The effect of the insulating materials and their content on the high-frequency magnetic properties of the compacted cores were investigated. The Fe-based nanocrystalline alloy powder cores using phenol resin exhibit stable permeability over 1 MHz, showing excellent high-frequency characteristics. The core loss was reduced significantly and the dc-bias property was improved by using phenol resin. Uniform and good insulation by phenol resin leads to the excellent high-frequency characteristics of the cores. Silicon resin as an insulating material was also effective in improving the high frequency characteristics of the Fe-based nanocrystalline alloy powder cores. However, an appropriate coating process for silicon resin should be applied in order to achieve more improved high frequency characteristics of the nanocrystalline alloy powder cores by controlling the thickness of coated layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Large plastic stability in magnesium alloys: crystalline vs. amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boissiere, R.; Puech, S.; Blandin, J.J. [Institut National Polytechnique de Grenoble (INPG), SIMaP Laboratory - GPM2 group, CNRS/UJF, Domaine Universitaire, Saint-Martin d' Heres (France)

    2008-04-15

    Except if strain induces damage, the plastic stability can be roughly estimated thanks to the value of the strain rate sensitivity parameter m. In conventional magnesium alloys, moderate values of m (typically close to 0.3) can be frequently obtained during high temperature deformation. Such values allow reaching significant elongations to fracture. For alloys displaying fine grains, superplastic properties associated with values of m of about 0.5 or more are achievable leading to large elongations to fracture in optimized conditions for which damage processes remain limited. Quite recently, amorphous magnesium alloys have been produced in bulk conditions. In appropriate conditions of deformation, these alloys display Newtonian behaviour (i.e. m=1). With such rheologies, the plastic stability is expected to be maximal. In this presentation, features in relation with high temperature deformation of amorphous and crystalline magnesium alloys will be compared and apparent similitudes and differences will be discussed. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  9. Microstructural Characterization and Wear Properties of Fe-Based Amorphous-Crystalline Coating Deposited by Twin Wire Arc Spraying

    Directory of Open Access Journals (Sweden)

    Ana Arizmendi-Morquecho

    2014-01-01

    Full Text Available Twin wire arc spraying (TWAS was used to produce an amorphous crystalline Fe-based coating on AISI 1018 steel substrate using a commercial powder (140MXC in order to improve microhardness and wear properties. The microstructures of coating were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM as well as the powder precursor. Analysis in the coating showed the formation of an amorphous matrix with boron and tungsten carbides randomly dispersed. At high amplifications were identified boron carbides at interface boron carbide/amorphous matrix by TEM. This kind of carbides growth can be attributed to partial crystallization by heterogeneous nucleation. These interfaces have not been reported in the literature by thermal spraying process. The measurements of average microhardness on amorphous matrix and boron carbides were 9.1 and 23.85 GPa, respectively. By contrast, the microhardness values of unmelted boron carbide in the amorphous phase were higher than in the substrate, approaching 2.14 GPa. The relative wear resistance of coating was 5.6 times that of substrate. These results indicate that the twin wire arc spraying is a promising technique to prepare amorphous crystalline coatings.

  10. Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

    Directory of Open Access Journals (Sweden)

    Andrea Milanti

    2014-01-01

    Full Text Available Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C manufactured by High Velocity Oxygen Fuel (HVOF thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C and hard-metal (WC-CoCr coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

  11. Determination of boron in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grazhulene, S.S.; Grossman, O.V.; Kuntscher, K.K.; Malygina, L.I.; Muller, E.N.; Telegin, G.F.

    1985-10-01

    In the determination of boron in amorphous alloys containingFe, Co, B, Si, Ni, and P having unusal magnetic and electrical properties, precise analysis and rapid analysis are necessary. To improve the metrological properties of the existing procedure, to find a rapid determination of boron in amorphous alloys, and to verify the accuracy of the results, in the present work the optimization of the photometric determination after extraction of the BF/sup -//sub 4/ ion pair with methylene blue has been studied, and a boron determination by flame photometry using selective methylation has been developed. The determination of boron by the flame photometric and spectrophotometric methods is shown. When a highly precise determination is needed, the spectrophotometric procedure can be used. This procedure is distinguished by its labor intensity and duration. When the need for reproducibility is less severe, the rapid flame photometric procedure is best.

  12. Phase formation and crystallization behavior of melt spun Sm-Fe-based alloys

    International Nuclear Information System (INIS)

    Shield, J.E.

    1999-01-01

    The phase formation and microstructures of Sm-Fe alloys have been investigated at Sm levels of 11 and 17 atomic percent and with alloying additions of Ti and C. At lower Sm content, virtually phase pure SmFe 7 formed, while higher Sm content resulted in the formation of SmFe 7 , SmFe 2 and amorphous phases. The addition of Ti and C resulted in greater stability and a larger volume fraction of the amorphous phase. The binary Sm-Fe alloys at both Sm levels had tremendously variable microstructures, with large discrepancies in grain size and phase distribution from region to region. The addition of Ti and C tended to result in a more homogeneous microstructure, as well as a refinement in the microstructural scale. (orig.)

  13. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  14. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    Science.gov (United States)

    Farmer, Joseph C; Wong, Frank M.G.; Haslam, Jeffery J; Ji, Xiaoyan; Day, Sumner D; Blue, Craig A; Rivard, John D.K.; Aprigliano, Louis F; Kohler, Leslie K; Bayles, Robert; Lemieux, Edward J; Yang, Nancy; Perepezko, John H; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J

    2013-09-03

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  15. Magnetic structure of Fe-based amorphous and thermal annealed microwires

    Energy Technology Data Exchange (ETDEWEB)

    Olivera, J. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Provencio, M. [Instituto de Ciencia de Materiales, CSIC, Cantoblanco, 28049 Madrid (Spain); Prida, V.M. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Hernando, B. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain)]. E-mail: grande@pinon.ccu.uniovi.es; Santos, J.D. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Perez, M.J. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Gorria, P. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Sanchez, M.L. [Depto. Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Belzunce, F.J. [Depto. Ciencia de los Materiales e Ingenieria Metalurgica, Universidad de Oviedo, Independencia 13, 33004 Oviedo (Spain)

    2005-07-15

    The magnetic structure of amorphous and thermal annealed glass coated microwires is studied by thermomagnetic, DSC, and Bitter domain pattern techniques. The long-range dipolar interaction between parallel aligned microwires and the appearance of large Barkhausen jumps steps in the axially magnetized loops are discussed in terms of reversal magnetization process.

  16. Pulsed laser deposition of Co- and Fe-based amorphous magnetic films and multilayers

    Czech Academy of Sciences Publication Activity Database

    Acquaviva, S.; Caricato, A. P.; D'Anna, E.; Fernández, M.; Luches, A.; Frait, Zdeněk; Majková, E.; Ozvold, M.; Luby, S.; Mengucci, P.

    2003-01-01

    Roč. 433, 1-2 (2003), s. 252-258 ISSN 0040-6090 Grant - others:NATO(XX) PST.CLG.978058; VEGA(SK) 2/1106/22 Institutional research plan: CEZ:AV0Z1010914 Keywords : laser ablation * amorphous magnetic materials * magnetic thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.598, year: 2003

  17. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Devitrification of rapidly quenched Al–Cu–Ti amorphous alloys

    Indian Academy of Sciences (India)

    Unknown

    spinning, the entire apparatus was ... The crystallization behaviour of these amorphous alloys has been studied using DSC 2910 (TA ... Thus the change in the structure of amorphous Al50Cu45Ti5 and Al45Cu45Ti10 alloys may be summarized as ...

  19. Local atomic order in nanocrystalline Fe-based alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Jartych, E.

    2003-01-01

    Using the 57 Fe Moessbauer spectroscopy, a local atomic order in nanocrystalline alloys of iron with Al, Ni, W and Mo has been determined. Alloys were prepared by mechanical alloying method. Analysis of Moessbauer spectra was performed on the basis of the local environment model in terms of Warren-Cowley parameters. It was shown that impurity atoms are not randomly distributed in the volume of the first and the second co-ordination spheres of 57 Fe nuclei and they form clusters

  20. Transformation processes during annealing of Al-amorphous alloys

    International Nuclear Information System (INIS)

    Petrescu, N.; Petrescu, M.; Calin, M.; Jianu, A.D.; Fecioru, M.

    1993-01-01

    As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.)

  1. Transformation processes during annealing of Al-amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Petrescu, N. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Petrescu, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Calin, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Jianu, A.D. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) IFTM-Bucharest (Romania)); Fecioru, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) DACIA Enterprise-Bucharest (Romania))

    1993-11-01

    As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.).

  2. Brazing Inconel 625 Using Two Ni/(Fe)-Based Amorphous Filler Foils

    Science.gov (United States)

    Chen, Wen-Shiang; Shiue, Ren-Kae

    2012-07-01

    For MBF-51 filler, the brazed joint consists of interfacial grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr-rich matrix. In contrast, the VZ-2106 brazed joint is composed of interfacial Nb6Ni16Si7 precipitates as well as grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr/Fe-rich matrix. The maximum tensile strength of 443 MPa is obtained from the MBF-51 brazed specimen. The tensile strengths of VZ-2106 brazed joints are approximately 300 MPa. Both amorphous filler foils demonstrate potential in brazing IN-625 substrate.

  3. Salt Fog Testing Iron-Based Amorphous Alloys

    International Nuclear Information System (INIS)

    Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

    2007-01-01

    Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

  4. Magnetism and high magnetic-field-induced stability of alloy carbides in Fe-based materials.

    Science.gov (United States)

    Hou, T P; Wu, K M; Liu, W M; Peet, M J; Hulme-Smith, C N; Guo, L; Zhuang, L

    2018-02-14

    Understanding the nature of the magnetic-field-induced precipitation behaviors represents a major step forward towards unravelling the real nature of interesting phenomena in Fe-based alloys and especially towards solving the key materials problem for the development of fusion energy. Experimental results indicate that the applied high magnetic field effectively promotes the precipitation of M 23 C 6 carbides. We build an integrated method, which breaks through the limitations of zero temperature and zero external field, to concentrate on the dependence of the stability induced by the magnetic effect, excluding the thermal effect. We investigate the intimate relationship between the external field and the origins of various magnetics structural characteristics, which are derived from the interactions among the various Wyckoff sites of iron atoms, antiparallel spin of chromium and Fe-C bond distances. The high-magnetic-field-induced exchange coupling increases with the strength of the external field, which then causes an increase in the parallel magnetic moment. The stability of the alloy carbide M 23 C 6 is more dependent on external field effects than thermal effects, whereas that of M 2 C, M 3 C and M 7 C 3 is mainly determined by thermal effects.

  5. Density measurement of amorphous SixGe1-x alloys

    International Nuclear Information System (INIS)

    Laaziri, K.; Roorda, S.; Cliche, L.

    1994-01-01

    The atomic density of amorphous Si x Ge 1-x alloys (x = 1, 0.85, 0.67, 0.50, 0.20 and 0) has been measured. Mono-crystalline Si x Ge 1-x layers were implanted with 1.50-2.75 MeV Si 2+ and Ge 2+ ions to produce the amorphous material. Using surface profilometry and RBS/channeling, it was found that amorphous alloys are less dense than the crystalline alloys, and that Vegard's law underestimates the a-Si x Ge 1-x density. (orig.)

  6. Structural observation of amorphous alloys by neutron diffraction

    International Nuclear Information System (INIS)

    Fukunaga, Toshiharu; Itoh, Keiji

    2006-01-01

    Neutron diffraction is a powerful tool to elucidate the atomic arrangement of amorphous alloys because of characteristic scattering lengths of constituent elements. For hydrogen absorption amorphous alloys H/D isotopic substitution was employed to observe the location of deuterium atoms because the neutron coherent scattering length of deuterium is large enough to observe in comparison with those of the constituent atoms. Moreover, Reverse Monte Carlo (RMC) modeling has been recognized to be an excellent method for visualizing the three-dimensional atomic arrangement of amorphous alloys, based on the results of neutron and X-ray diffraction experiments. Therefore, the combination of neutron, X-ray diffraction experiments and the RMC modeling was used to clarify the topological characteristics of the structure of amorphous alloys. (author)

  7. Phase transformations of amorphous semiconductor alloys under high pressures

    CERN Document Server

    Antonov, V E; Fedotov, V K; Harkunov, A I; Ponyatovsky, E G

    2002-01-01

    The paper reviews the results of experimental studies and thermodynamical modelling of metastable T-P diagrams of initially amorphous GaSb-Ge and Zn-Sb alloys which provide a new insight into the problem of pressure-induced amorphization.

  8. Amorphization of C-implanted Fe(Cr) alloys

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  9. 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.

  10. Features of exoelectron emission in amorphous metallic alloys

    CERN Document Server

    Veksler, A S; Morozov, I L; Semenov, A L

    2001-01-01

    The peculiarities of the photothermostimulated exoelectron emission in amorphous metallic alloys of the Fe sub 6 sub 4 Co sub 2 sub 1 B sub 1 sub 5 composition are studied. It is established that the temperature dependences of the exoelectron emission spectrum adequately reflect the two-stage character of the amorphous alloy transition into the crystalline state. The exoelectron emission spectrum is sensitive to the variations in the modes of the studied sample thermal treatment. The thermal treatment of the amorphous metallic alloy leads to growth in the intensity of the exoelectrons yield. The highest growth in the intensify of the exoelectron emission was observed in the alloys at the initial stage of their crystallization

  11. Amorphous Alloy Membranes for High Temperature Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Coulter, K. [Southwest Research Inst. (SwRI), San Antonio, TX (United States)

    2013-09-30

    At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute® (SwRI®), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 °C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys

  12. Crystallization characteristics of amorphous alloys of FeZr

    International Nuclear Information System (INIS)

    Rozhan, M. Idrus; Grundy, P.J.

    1993-01-01

    The crystallization characteristics of sputter-deposited amorphous alloys of Fe 100-x Zr x prepared at zirconium concentrations between 9 and 89 at.% was investigated. The transformation of the alloys from the amorphous to the crystalline state has been examined by thermal analysis, electrical resistance and X-ray diffraction. The crystallization temperatures were determined by differential scanning calorimetry (DSC) and electrical resistance as a function of temperature. The final phases were determined by X-ray diffraction. The activation energies were calculated from the Kissinger plots and the heats of crystallization were calculated and correlations between the thermal analysis and the resistance results are presented

  13. Superconducting properties of amorphous Zr-Ge binary alloys

    International Nuclear Information System (INIS)

    Inoue, A.; Takahashi, Y.; Toyota, N.; Fukase, T.; Masumoto, T.

    1982-01-01

    A new type of refractory metal-metalloid amorphous alloys exhibiting superconductivity has been found in a binary Zr-Ge system by a modified melt-spinning technique. Specimens are in the form of continuous ribbons 1 to 2 mm wide and 0.02 to 0.03 mm thick. The germanium content in the amorphous alloys is limited to the range of 13 to 21 at%. These amorphous alloys are so ductile that no cracks are observed even after closely contacted bending test. Data are reported for various alloy compositions for the Vickers hardness and crystallization temperature, the tensile fracture strength, superconducting transition temperature Tsub(c), upper critical magnetic field, critical current density in the absence of an applied field, upper critical field gradient at Tsub(c) and the electrical resistivity at 4.2 K. The Ginzburg-Landau (GL) parameter and the GL coherence length were estimated to be 72 to 111 and about 7.9 nm, respectively, from these experimental values by using the Ginzburg-Landau-Abrikosov-Gorkov theory and hence it is concluded that the Zr-Ge amorphous alloys are extremely 'soft' type-II superconductor with high degree of dirtiness which possesses the Tsub(c) values higher than zirconium metal, in addition to high strength combined with good ductility. (author)

  14. Fabrication of Ti-Cu-Ni-Al amorphous alloys by mechanical alloying and mechanical milling

    International Nuclear Information System (INIS)

    Kishimura, Hiroaki; Matsumoto, Hitoshi

    2011-01-01

    Research highlights: → Ti-based amorphous alloys are produced by the mechanical alloying and by the mechanical milling. → The amorphization by the mechanical alloying is slower than that by the mechanical milling. → Activation energy and temperature of crystallization of both alloys are different. - Abstract: Ti-based amorphous alloy powders were synthesized by the mechanical alloying (MA) of pure elements and the mechanical milling (MM) of intermetallic compounds. The amorphous alloy powders were examined by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Scanning electron micrographs revealed that the vein morphology of these alloy powders shows deformation during the milling. The energy-dispersive X-ray spectral maps confirm that each constituent is uniformly dispersed, including Fe and Cr. The XRD and DSC results showed that the milling time required for amorphization for the MA of pure elements was longer than that of the MM for intermetallic compounds. The activation energy and crystallization temperature of the MA powder are different from those of the MM powder.

  15. Surface segregations in amorphous magnetically soft alloy under oxidation

    International Nuclear Information System (INIS)

    Bayankin, V.A.; Vasil'ev, V.Yu.; Volkova, I.B.; Skvortsova, N.G.; Smirnova, O.I.

    1997-01-01

    Using the Auger electron spectroscopy and electron reflecting diffraction the effects of high temperature annealing and electro-chemical treatment on chemical composition and atomic structure of amorphous magnetically soft alloy Co 57 Fe 5 Ni 10 Si 11 B 7 were investigated. It is shown the surface layers on the base of silicon carbide are formed during annealing while during electro-chemical treatment a cobalt borides are formed. Besides, during electro-chemical treatment the amorphous structure with different interatomic space are saved depending on time. At the time, mechanical properties of the alloy are not worse and it may be used for manufacturing of magnetodrives from amorphous magnetically soft materials [ru

  16. Amorphous Metallic Alloys: Pathways for Enhanced Wear and Corrosion Resistance

    Science.gov (United States)

    Aditya, Ayyagari; Felix Wu, H.; Arora, Harpreet; Mukherjee, Sundeep

    2017-11-01

    Amorphous metallic alloys are widely used in bulk form and as coatings for their desirable corrosion and wear behavior. Nevertheless, the effects of heat treatment and thermal cycling on these surface properties are not well understood. In this study, the corrosion and wear behavior of two Zr-based bulk metallic glasses were evaluated in as-cast and thermally relaxed states. Significant improvement in wear rate, friction coefficient, and corrosion penetration rate was seen for both alloys after thermal relaxation. A fully amorphous structure was retained with thermal relaxation below the glass transition. There was an increase in surface hardness and elastic modulus for both alloys after relaxation. The improvement in surface properties was explained based on annihilation of free volume.

  17. Aluminium base amorphous and crystalline alloys with Fe impurity

    International Nuclear Information System (INIS)

    Sitek, J.; Degmova, J.

    2006-01-01

    Aluminium base alloys show remarkable mechanical properties, however their low thermal stability still limits the technological applications. Further improvement of mechanical properties can be reached by partial crystallization of amorphous alloys, which gives rise to nanostructured composites. Our work was focused on aluminium based alloys with Fe, Nb and V additions. Samples of nominal composition Al 90 Fe 7 Nb 3 and Al 94 Fe 2 V 4 were studied in amorphous state and after annealing up to 873 K. From Moessbauer spectra taken on the samples in amorphous state the value of f-factor was determined as well as corresponding Debye temperatures were calculated. Annealing at higher temperatures induced nano and microcrystalline crystallization. Moessbauer spectra of samples annealed up to 573 K are fitted only by distribution of quadrupole doublets corresponding to the amorphous state. An increase of annealing temperature leads to the structural transformation, which consists in growth of nanometer sized aluminium nuclei. This is partly reflected in Moessbauer parameters. After annealing at 673 K intermetallic phase Al 3 Fe and other Al-Fe phases are created. In this case Moessbauer spectra are fitted by quadrupole doublets. During annealing up to 873 K large grains of Fe-Al phases are created. (authors)

  18. Consolidation of partially amorphous Al-Fe-Zr alloys

    International Nuclear Information System (INIS)

    Rodrigues, C.A.D.; Leiva, D.R.; Kiminami, C.S.; Botta F., W.J.

    2002-01-01

    We present in this work the preparation of partially amorphous Al-Fe-Zr alloy powders by mechanical alloying and their consolidation by hot-extrusion. Elemental powder mixture corresponding to the composition Al 90 Fe 7 Zr 3 was mechanically alloyed with milling power of 10:1 and time varying from 5 h to 100 h. Milling for 60 h resulted in a powder alloy microstructure composed mostly of nanocrystalline Al and amorphous phase. Heat treatment of such powder resulted in the formation of Al and also the equilibrium intermetallic Al 3 Zr and Al 13 Fe 4 phases. The alloy powders have been hot extruded at 450 C and the microstructure of the consolidated alloy was very fine and composed also by the three equilibrium phases; Al, Al 3 Zr and Al 13 Fe 4 . This fine microstructure resulted in yield stress values in compression tests at room temperature in the range of 780MPa, associated with elongation to fracture of 10%. (orig.)

  19. Properties of amorphous FeCoB alloy particles (abstract)

    DEFF Research Database (Denmark)

    Charles, S. W.; Wells, S.; Meagher, A.

    1988-01-01

    Amorphous and crystalline alloy particles (0.05–0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x......-ray diffraction. Magnetic measurements of the saturation magnetization, coercivity, and remanence of the particles have been measured. The transition from the amorphous-to-crystalline state has been studied using differential scanning calorimetry (DSC) and thermomagnetometry up to a temperature of 450 °C (see Fig...

  20. Positron lifetime measurements on electron irradiated amorphous alloys

    International Nuclear Information System (INIS)

    Moser, P.; Hautojaervi, P.; Chamberod, A.; Yli-Kauppila, J.; Van Zurk, R.

    1981-08-01

    Great advance in understanding the nature of point defects in crystalline metals has been achieved by employing positron annihilation technique. Positrons detect vacancy-type defects and the lifetime value of trapped positrons gives information on the size of submicroscopic vacancy aglomerates and microvoids. In this paper it is shown that low-temperature electron irradiations can result in a considerable increase in the positron lifetimes in various amorphous alloys because of the formation of vacancy-like defects which, in addition of the pre-existing holes, are able to trap positrons. Studied amorphous alloys were Fe 80 B 20 , Pd 80 Si 20 , Cu 50 Ti 50 , and Fe 40 Ni 40 P 14 B 6 . Electron irradiations were performed with 3 MeV electrons at 20 K to doses around 10 19 e - /cm 2 . After annealing positron lifetime spectra were measured at 77 K

  1. Temperature dependence of the magnetic properties of ferromagnetic amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, P.

    1979-01-01

    The magnetic hysteresis properties of amorphous alloys have recently been discussed in terms of an exchange-enhanced applied field. This absolute-zero model is here extended to finite temperatures. The modified treatment predicts a remanent magnetization which is unaffected by thermal activation while the coercive force falls (finally to zero) as temperature increases. Comparison with experiment for TbFe/sub 2/ suggests that regions of volume approx. =7500 A/sup 3/ reverse coherently.

  2. Formation of amorphous metal alloys by chemical vapor deposition

    Science.gov (United States)

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  3. Understanding self ion damage in FCC Ni-Cr-Fe based alloy using X-ray diffraction techniques

    Science.gov (United States)

    Halder Banerjee, R.; Sengupta, P.; Chatterjee, A.; Mishra, S. C.; Bhukta, A.; Satyam, P. V.; Samajdar, I.; Dey, G. K.

    2018-04-01

    Using X-ray diffraction line profile analysis (XRDLPA) approach the radiation response of FCC Ni-Cr-Fe based alloy 690 to 1.5 and 3 MeV Ni2+ ion damage was quantified in terms of its microstructural parameters. These microstructural parameters viz. average domain size, microstrain and dislocation density were found to vary anisotropically with fluence. The anisotropic behaviour is mainly attributable to presence of twins in pre-irradiated microstructure. After irradiation, surface roughness increases as a function of fluence attributable to change in surface and sub-surface morphology caused by displacement cascade, defects and sputtered atoms created by incident energetic ion. The radiation hardening in case of 1.5 MeV Ni2+ irradiated specimens too is a consequence of the increase in dislocation density formed by interaction of radiation induced defects with pre-existing dislocations. At highest fluence there is an initiation of saturation.

  4. Multi-scale Modelling of bcc-Fe Based Alloys for Nuclear Applications

    International Nuclear Information System (INIS)

    Malerba, Lorenzo

    2008-01-01

    Understanding the basic mechanisms that determine microstructure changes in neutron irradiated steels is vital for a safe lifetime management of existing nuclear reactors and a safe design of future nuclear options. Low-alloyed ferritic steels containing Cu, Ni, Mn and Si as principal solute atoms are used as structural materials for current reactor vessels. The microstructural evolution under irradiation in alloys is decided by the interplay between defect formation and thermodynamic driving forces, together determining the appearance of phase transformations (precipitation, segregation,...) and favouring or delaying the nucleation and growth of point-defect clusters, their diffusion and their mutual recombination or removal at sinks. A reliable description of the production, evolution and accumulation of radiation damage must therefore start from the atomic level and requires being able to describe multicomponent systems for timescales ranging from few picoseconds to years. This goal demands firstly the fabrication of interatomic potentials for alloys that must be both consistent with the thermodynamic properties of the system and capable of reproducing correctly the characteristic solute-point defect interactions, versus ab initio or experimental data. Secondly the performance of extensive molecular dynamics (MD) simulations, to grasp the main mechanisms of defect production, diffusion, mutual interaction, and interaction with solute atoms and impurities. Thirdly, the development of simulation tools capable of describing the microstructure evolution beyond the time-frame and length-scale of MD, while reproducing as much as possible the atomic-level origin of the mechanisms governing the evolution of the system, including phase changes. In this presentation the results of recent efforts made in this direction in the case of Fe-Cu, Fe-Cr and Fe-Ni alloys, as basic model alloys for the description of steels of technological relevance, are highlighted. In particular

  5. Surface-Activated Amorphous Alloy Fuel Electrodes for Methanol Fuel Cell

    OpenAIRE

    Asahi, Kawashima; Koji, Hashimoto; The Research Institute for Iron, Steel and Other Metals; The Research Institute for Iron, Steel and Other Metals

    1983-01-01

    Amorphous alloy electrodes for electrochemical oxidation of methanol and its derivatives were obtained by the surface activation treatment consisting of electrodeposition of zinc on as-quenched amorphous alloy substrates, heating at 200-300℃ for 30 min, and subsequently leaching of zinc in an alkaline solution. The surface activation treatment provided a new method for the preparation of a large surface area on the amorphous alloys. The best result for oxidation of methanol, sodium formate an...

  6. Magnetic properties of iron-based amorphous and nanocrystalline Fe-Zr-X-B (X: Cu, Al) alloy films

    International Nuclear Information System (INIS)

    Goscianska, I.; Tolinski, T.; Ratajczak, H.; Sovak, P.; Dlugos, R.; Konc, M.

    2000-01-01

    Thermal stability and magnetic properties of thin films, of a few Fe-based amorphous and nanocrystalline alloys, have been studied. The alloys belong to the class Fe-M-B, whose representatives are Fe 87 Zr 4 CuB 8 , Fe 87 Zr 7 B 6 , and Fe 87 Zr 7 AlB 5 and are of particular interest because of their wide variety of magnetic properties. The films were prepared by flash evaporation onto liquid nitrogen cooled substrates. Measurements of the Kerr effect, the Hall effect, and ferromagnetic resonance in the films were carried out as functions of the annealing temperature. It was found that the changes in the coercive field H c , resonance linewidth ΔH pp , effective magnetization M eff , Hall parameters, and resistance were correlated with the structural changes in the studied films. (author)

  7. Thermomechanical behavior of an Fe-based shape memory alloy: transformation conditions and hystereses

    International Nuclear Information System (INIS)

    Tanaka, K.; Nishimura, F.; Tobushi, H.; Oberaigner, E.R.; Fischer, F.D.

    1995-01-01

    Transformation/thermomechanical behavior in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy during thermomechanical loading is investigated. The transformation lines in the stress-temperature plane are strongly influenced by the parameters characterizing the thermomechanical loading. The transformation start condition, the martensite start stress and the austenite start temperature, is carefully measured to compare the results with the other experimental and theoretical observations. The stress-strain-temperature hysteresis loops, full and sub, are determined during cyclic loading. (orig.)

  8. Crystallization of amorphous phase in niobium alloys with oxygen

    International Nuclear Information System (INIS)

    Dekanenko, V.M.; Samojlenko, Z.A.; Revyakin, A.V.

    1982-01-01

    Crystallization and subsequent phase transformations of amorphous phase during annealings in the system Nb-O are studied. It is shown that quenching from liquid state of niobium alloys with oxygen with a rate of 10 5 -10 6 K/s results in partial crystallization of the melt. Phase transition from amorphous to crystal state at 670 K in all probability takes place without the change of chemical composition. After crystallization the decomposition of oversaturated solid solution on the basis of NbO takes place with the separation of low- temperature modification, γ-Nb 2 O 5 . Niobium pentoxide of both modifications during prolong annealings at 770 K and short- time annealings higher 1070 K disappears completely [ru

  9. Diffusion studies in amorphous NiZr alloys

    International Nuclear Information System (INIS)

    Hahn, H.; Averback, R.S.; Hoshino, K.; Rothman, S.J.

    1987-06-01

    Tracer impurity and self diffusion measurements have been made on amorphous (a-) NiZr alloys using radioactive tracer, Secondary Ion Mass Spectrometry and Rutherford backscattering techniques. The temperature dependence of diffusion in a-NiZr can be represented in the form D = D 0 exp(-Q/kT), with no structural relaxation effects being observed. The mobility of an atom in a-NiZr increased dramatically with decreasing atomic radius of the diffusing atom and also with decreasing Ni content for Ni concentrations below ≅40 at. %. These diffusion characteristics in a-NiZr are remarkably similar to those in α-Zr and α-Ti. These mechanisms assume that Zr and Ti provide a close packed structure, either crystalline or amorphous, through which small atoms diffuse by an interstitial mechanism and large atoms diffuse by a vacancy mechanism. 12 refs., 2 figs., 2 tabs

  10. High tunneling magnetoresistance ratio in perpendicular magnetic tunnel junctions using Fe-based Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu-Pu, E-mail: Vicky-sg1015@hotmail.com [Department of Electrical and Computer Engineering, National University of Singapore (Singapore); Data Storage Institute, Agency for Science, Technology and Research - A*STAR (Singapore); Lim, Sze-Ter; Han, Gu-Chang, E-mail: HAN-Guchang@dsi.a-star.edu.sg [Data Storage Institute, Agency for Science, Technology and Research - A*STAR (Singapore); Teo, Kie-Leong, E-mail: eleteokl@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore (Singapore)

    2015-12-21

    Heulser alloys Fe{sub 2}Cr{sub 1−x}Co{sub x}Si (FCCS) with different Co compositions x have been predicted to have high spin polarization. High perpendicular magnetic anisotropy (PMA) has been observed in ultra-thin FCCS films with magnetic anisotropy energy density up to 2.3 × 10{sup 6 }erg/cm{sup 3}. The perpendicular magnetic tunnel junctions (p-MTJs) using FCCS films with different Co compositions x as the bottom electrode have been fabricated and the post-annealing effects have been investigated in details. An attractive tunneling magnetoresistance ratio as high as 51.3% is achieved for p-MTJs using Fe{sub 2}CrSi (FCS) as the bottom electrode. The thermal stability Δ can be as high as 70 for 40 nm dimension devices using FCS, which is high enough to endure a retention time of over 10 years. Therefore, Heusler alloy FCS is a promising PMA candidate for p-MTJ application.

  11. Deformation-driven catalysis of nanocrystallization in amorphous Al alloys

    Directory of Open Access Journals (Sweden)

    Rainer J. Hebert

    2016-10-01

    Full Text Available Nanocrystals develop in amorphous alloys usually during annealing treatments with growth- or nucleation-controlled mechanisms. An alternative processing route is intense deformation and nanocrystals have been shown to develop in shear bands during the deformation process. Some controversy surrounded the idea of adiabatic heating in shear bands during their genesis, but specific experiments have revealed that the formation of nanocrystals in shear bands has to be related to localized deformation rather than thermal effects. A much less debated issue has been the spatial distribution of deformation in the amorphous alloys during intense deformation. The current work examines the hypothesis that intense deformation affects the regions outside shear bands and even promotes nanocrystal formation in those regions upon annealing. Melt-spun amorphous Al88Y7Fe5 alloy was intensely cold rolled. Microcalorimeter measurements at 60 °C indicated a slight but observable growth of nanocrystals in shear bands over the annealing time of 10 days. When the cold-rolled samples were annealed at 210 °C for one hour, transmission electron images did not show any nanocrystals for as-spun ribbons, but nanocrystals developed outside shear bands for the cold rolled samples. X-ray analysis indicated an increase in intensity of the Al peaks following the 210 °C annealing while the as-spun sample remained “X-ray amorphous”. These experimental observations strongly suggest that cold rolling affects regions (i.e., spatial heterogeneities outside shear bands and stimulates the formation of nanocrystals during annealing treatments at temperatures well below the crystallization temperature of undeformed ribbons.

  12. Relationship between thermomechanical treatment, microstructure and α' martensite in stainless Fe-based shape memory alloys

    International Nuclear Information System (INIS)

    Otubo, J.; Mei, P.R.; Shinohara, A.H.; Suzuki, C.K.

    1999-01-01

    This work presents some preliminary results relating training treatment, training temperature and the formation of α' martensite to the shape recovery effect of stainless shape memory alloys. For the composition tested, the sample shows some mechanical memory (constant tensile stress at 4% strain and constant yield stress throughout the training cycles) with a very good shape recovery (95% after 4% tensile strain) at a training temperature of 873 K. Its residual strain is related to the generation of perfect dislocations only. For the sample trained at 723 K, the residual strain could be attributed to incomplete reversion of stress-induced ε martensite, in part due to the blocking effect of α' martensite and also to the generation of perfect dislocations. The influence of α' martensite on shape recovery is relative and is dependent on training temperature, and the preferential growth of α' martensite is shown to occur for large grain size. (orig.)

  13. Formation and characterization of amorphous-nanocrystalline Al{sub 80}Fe{sub 10}M{sub 10} [M = Fe, Nb, Ti, Ni, (Ni{sub 0.5}Ti{sub 0.5})] alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tavoosi, M., E-mail: Ma.tavoosi@gmail.com [Department of Material Engineering, Malek-Ashtar University of Technology (MUT), Shahin-shahr, Isfahan (Iran, Islamic Republic of); Department of Material Engineering, Isfahan University of Technology (IUT), Isfahan (Iran, Islamic Republic of); Karimzadeh, F.; Enayati, M.H. [Department of Material Engineering, Isfahan University of Technology (IUT), Isfahan (Iran, Islamic Republic of)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Formation of amorphous-nanocrystalline Al-Fe based alloys by means of mechanical alloying. Black-Right-Pointing-Pointer The effect of Ni, Ti and Nb on glass forming ability of Al-Fe based alloys. Black-Right-Pointing-Pointer The effect of Ni, Ti and (Ni{sub 50}Ti{sub 50}) on thermal stability of produced amorphous phases. - Abstract: In this study, the formation and characterization of amorphous-nanocrystalline phases in Al{sub 80}Fe{sub 10}M{sub 10} [M = Fe, Ti, Nb, Ni, (Ni{sub 0.5}Ti{sub 0.5})] powder mixtures by means of mechanical alloying (MA) have been investigated. The milled samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transition electron microscopy (TEM). Performed mechanical alloying in different alloying systems showed that, only in Al{sub 80}Fe{sub 10}Ni{sub 10}, Al{sub 80}Fe{sub 10}Ti{sub 10} and Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} powder mixtures amorphous phase can be formed. The produced amorphous phases in these systems, exhibit one-stage crystallization on heating (at temperature up that 850 Degree-Sign C) and the activation energy for crystallization is more than 300 kJ/mol. The crystallization mechanism of amorphous phase in these three systems is different and the thermal stability of amorphous phase in Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} alloy is more than Al{sub 80}Fe{sub 10}Ni{sub 10} and Al{sub 80}Fe{sub 10}Ti{sub 10}.

  14. Abrasive Wear Properties of Fe-Based Alloys Designed for Mining Applications

    Directory of Open Access Journals (Sweden)

    Wieczorek A. N.

    2017-09-01

    Full Text Available The purpose of this study was to determine experimentally the wear properties of 5 groups of iron-based alloys used in the mining and transport machines exposed to the action of a hard abrasive material. The groups of materials to be examined included austempered ductile irons (ADI, steels and cast steel designed for quenching and tempering and for surface hardening, hard-wearing hardened steels and structural steels. The wear tests were carried out on a disc-on-disc test rig. The test samples were examined under conditions of sliding mating, while the leading destructive process was microcutting of the surface with loose corundum grain. The loss of mass of the examined samples was measured as a parameter characterizing the wear. Base on it, other wear coefficients were determined, for example the volume loss, the intensity of wear and the wear rate. The volume loss values determined were presented as a function of the strength and the initial hardness. Based on the results obtained, it was found that the hardened steel and ADI had comparable wear properties, while the ADI surface was strengthened probably as a result of the transition of austenite into martensite and the impact of the deformation of the graphite contained in ADI on the abrasive wear of the surface.

  15. Study of oxidation behaviour of Zr-based bulk amorphous alloy Zr 65 ...

    Indian Academy of Sciences (India)

    The oxidation behaviour of Zr-based bulk amorphous alloy Zr65Cu17.5Ni10Al7.5 has been studied in air environment at various temperatures in the temperature range 591–684 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy in the amorphous phase obeys the parabolic rate law for oxidation ...

  16. Defects in hyperpure Fe-based alloys created by 3 MeV e{sup -}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.H.; Moser, P. [CEA Centre d`Etudes de Grenoble, 38 (France). Dept. de Recherche Fondamentale sur la Matiere Condensee; Akamatsu, M.; Van Duysen, C. [Electricite de France (EDF), 77 - Ecuelles (France)

    1994-12-31

    Information about vacancy defects created in RPV (Reactor Pressure Vessels) steels after neutron irradiations are obtained via a simulation: the RPV steels are simulated by a series of high purity Fe-based alloys; the neutron irradiation is simulated by a 3 MeV electron irradiation; vacancy defects characteristics are obtained by positron lifetime techniques. Irradiations are made at 150 or 288 deg C, with a dose of 4*10{sup 19} e-/cm{sup 2}, and followed by isochronal annealing in the range 20-500 deg C. The observed vacancy defects are single trapped vacancies and small vacancy clusters, the size of which being lower than 10 empty atomic volumes (vacancy clusters containing more than 50 empty atomic volumes were never found). A large recovery step is observed between 200 and 400 deg C, after 150 deg C irradiation and attributed to vacancy-impurity detrapping, and also, vacancy cluster evaporation. The influence of C, Cu and Mo are presented. These results are in agreement with a model supposing, in pure Fe, single vacancy migration at -50 deg C and vacancy-impurity detrapping at 200 deg C. (authors). 4 figs., 15 refs.

  17. Cavitation erosion of Ti-Ni shape memory alloy deposited coatings and Fe base shape memory alloy solid

    International Nuclear Information System (INIS)

    Hattori, Shuji; Fujisawa, Seiji; Owa, Tomonobu

    2007-01-01

    In this study, cavitation erosion tests were carried out by using thermal spraying and deposition of Ti-Ni shape memory alloy for the surface coating. The results show the test speciment of Ti-Ni thermal spraying has many initial defects, so that the erosion resistance is very low. The erosion resistance of Ti-Ni deposit is about 5-10 times higher than that of SUS 304, thus erosion resistance of Ti-Ni deposit is better than that of Ti-Ni thermal spraying. The cavitation erosion tests were carried out by using Fe-Mn-Si with shape memory and gunmetal with low elastic modulus. The erosion resistance of Fe-Mn-Si shape memory alloy solid is about 9 times higher than that of SUS 304. The erosion resistance of gunmetal is almost the same as SUS 304, because the test specimen of gunmetal has many small defects on the original surface. (author)

  18. Low temperature irradiation effects on iron boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, A.

    1982-09-01

    Three Fe-B amorphous alloys (Fe 80 B 20 , Fe 27 Mo 2 B 20 and Fe 75 B 25 ) and the crystallized Fe 3 B alloy have been irradiated at the temperature of liquid hydrogen. Electron irradiation and irradiation by 10 B fission fragments induce point defects in amorphous alloys. These defects are characterized by an intrinsic resistivity and a formation volume. The threshold energy for the displacement of iron atoms has also been calculated. Irradiation by 235 U fission fragments induces some important structural modifications in the amorphous alloys [fr

  19. Low temperature irradiation effects on iron-boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, Alain.

    1983-01-01

    Three iron-boron amorphous alloys and the crystalline Fe 3 B alloy have been irradiated at liquid hydrogen temperature. 2,4 MeV electron irradiation induces the creation of point defects in the amorphous alloys as well as in the crystalline Fe 3 B alloy. These point defects can be assimilated to iron ''Frenkel pairs''. They have been characterized by determining their intrinsic electrical resistivity and their formation volume. The displacement threshold energy of iron atoms has also been determined. 10 B fission fragments induce, in these amorphous alloys, displacement cascades which lead to stable vacancy rich zones. This irradiation also leads to a structural disorder in relation with the presence of defects. 235 U fission fragments irradiation modifies drastically the structure of the amorphous alloys. The results have been interpreted on the basis of the coexistence of two opposite processes which induce local disorder and crystallisation respectively [fr

  20. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

    Science.gov (United States)

    Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

  1. Short range ordering and microstructure property relationship in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shariq, A.

    2006-07-01

    A novel algorithm, ''Next Neighbourhood Evaluation (NNE)'', is enunciated during the course of this work, to elucidate the next neighbourhood atomic vicinity from the data, analysed using tomographic atom probe (TAP) that allows specifying atom positions and chemical identities of the next neighbouring atoms for multicomponent amorphous materials in real space. The NNE of the Pd{sub 55}Cu{sub 23}P{sub 22} bulk amorphous alloy reveals that the Pd atoms have the highest probability to be the next neighbours to each other. Moreover, P-P correlation corroborates earlier investigations with scattering techniques that P is not a direct next neighbour to another P atom. Analogous investigations on the Fe{sub 40}Ni{sub 40}B{sub 20} metallic glass ribbons, in the as quenched state and for a state heat treated at 350 C for 1 hour insinuate a pronounced elemental inhomogeneity for the annealed state, though, it also depicts glimpse of a slight inhomogeneity for B distribution even for the as quenched sample. Moreover, a comprehensive microstructural investigation has been carried out on the Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy system. TEM and TAP investigations evince that the as cast bulk samples constitutes a composite structure of an amorphous phase and crystalline phase(s). The crystallization is essentially triggered at the mould walls due to heterogeneous nucleation. The three dimensional atomic reconstruction maps of the volume analysed by TAP reveal a complex stereological interconnected network of two phases. The phase that is rich in Zr and Al concentration is depleted in Co concentration while the phase that is rich in Co concentration is depleted both in Zr and Al. Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy splat samples exhibit a single exothermic crystallization peak contrary to the as cast bulk sample with a different T{sub g} temperature. A single homogeneous amorphous phase revealed by TEM investigations depicts that the faster cooling

  2. The crystallization of Al-Sm amorphous alloys

    International Nuclear Information System (INIS)

    Rizzi, P.; Baricco, M.; Battezzati, L.; Schumacher, P.; Greer, A.L.

    1995-01-01

    Amorphous alloys with composition Al 100-x Sm x (8 ≤ x ≤ 14) have been prepared by melt spinning in controlled atmosphere. The quenching conditions significantly influence the microstructure of as-quenched samples and their crystallization mechanisms. The crystallization was followed by means of DSC, XRD, TEM and SEM. Different mechanisms are observed as a function of composition. For low Sm content (Al 92 Sm 8 ), a primary crystallization occurs at about 180 C, with the formation of Al nanocrystals with a grain size of about 15 nm. A polymorphic crystallization is found in Al 90 Sm 10 , with the formation of a metastable intermetallic phase at about 220 C. For higher Sm content (Al 88 Sm 12 and Al 86 Sm 14 ), a eutectic crystallization at about 230 C gives a mixture of stable (Al and Al 11 Sm 3 ) and metastable phases. (orig.)

  3. Density of states in Mo-Ru amorphous alloys

    International Nuclear Information System (INIS)

    Miyakawa, W.

    1985-01-01

    The density of states is calculated for several compositions of amorphous Mo 1-x Ru x . In order to simulate amorphous clusters, the structures (atomic positions) utilized in the calculations were built from a small dense randomly packed unit of hard spheres with periodic boundary conditions. The density of states is calculated from a tight-binding Hamiltonian with hopping integrals parametrized in terms of the ddσ, ddΠ and ddδ molecular integrals. The results for pure Mo and pure Ru, compared in the canonical band aproximation, agree well with the literature. For binary alloys, the comparison of the calculated density of states with the rigid band aproximation results indicates that a more complex approach than the rigid band model must be used, even when the two atoms have similar bands, with band centers at nearly the same energy. The results also indicate that there is no relation between the peak in the superconducting critical temperature as a function of the number of valence eletrons per atom (e/a) in the region near Mo(e/a=6) and the peak of the density of states at the Fermi level in the same region, as has been sugested by some authors. (Author) [pt

  4. Pressure effects on Al89La6Ni5 amorphous alloy crystallization

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Jiang, Jianzhong; Zhou, T. J.

    2000-01-01

    The pressure effect on the crystallization of the Al89La6Ni5 amorphous alloy has been investigated by in situ high-pressure and high-temperature x-ray powder diffraction using synchrotron radiation. The amorphous alloy crystallizes in two steps in the pressure range studied (0-4 GPa). The first......(s). The applied pressure strongly affects the crystallization processes of the amorphous alloy. Both temperatures first decrease with pressure in the pressure range of 0-1 GPa and then increase with pressure up to 4 GPa. The results are discussed with reference to competing processes between the thermodynamic...

  5. Effect of neutron irradiation on Mo-Si amorphous alloys

    International Nuclear Information System (INIS)

    Ito, Fumitake; Hasegawa, Masayuki; Suzuki, Kenji; Honda, Toshihisa; Fukunaga, Toshiharu.

    1982-01-01

    The irradiation effects on Mo-Si amorphous alloys were investigated by means of X-ray diffraction and positron annihilation, and their electric resistance at low temperature was measured to examine the superconductivity of the alloys. The specimens of Mo 68 Si 32 and Mo 45 Si 55 were irradiated with the neutron fluence (E > 1 MeV) of about 9 x 10 18 n/cm 2 without temperature control in the Japanese Material Testing Reactor (JMTR). For these irradiated specimens, the X-ray diffraction experiment was performed to examine the irradiation effects on the radial distribution function, and the angular correlation curves for the positron annihilation were also measured. Both experiments showed that there was almost no irradiation effect. However, the width of the superconductive transition measured in Mo 68 Si 32 became extremely narrow due to neutron irradiation, and the transition temperature rose from 6.89 K to 7.03 K. On the other hand, in Mo 45 Si 55 , the width showed a tendency to become somewhat narrow, but the transition temperature shifted to the lower side. (Asami, T.)

  6. High speed cinematography of cracks spreading under failure of amorphous metallic alloys

    International Nuclear Information System (INIS)

    Tabachnikova, E.D.; Golovin, Y.I.; Makarov, M.V.; Shibkov, A.A.

    1997-01-01

    The results of experimental investigation of crack propagation velocity in amorphous alloys are presented. It is shown that there exists some correlation between crack velocity and fracture mode and morphology (orig.)

  7. Transformers with amorphous alloy nucleus in distribution system; Transformadores com nucleo de liga amorfa em sistemas de distribuicao

    Energy Technology Data Exchange (ETDEWEB)

    Luciano, Benedito Antonio; Freire, Raimundo Carlos Silverio [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Bezerra, Reno Barroso [Industria de Transformadores Itaipu, Campinas, SP (Brazil); Inacio, Renato Cucatu [Companhia de Energia Eletrica do Estado do Tocantins (CELTINS), TO (Brazil)

    2010-01-15

    This paper compares the performance of amorphous alloy nucleus with oriented grain silicon steel alloy, related to losses, energy efficiency and energy quality. Besides, are highlighted the process obtention of the amorphous alloys and the electric, magnetic and mechanicals, magneto thermal treatment, effect of oxidation properties, and etc. (author)

  8. Magnetoresistance and magnetic breakdown phenomenon in amorphous magnetic alloys

    International Nuclear Information System (INIS)

    Chen Hui-yu; Gong Xiao-yu

    1988-01-01

    Transverse magnetoresistance in amorphous magnetic alloys (Fe/sub 1-//sub x/CO/sub x/) 82 Cu/sub 0.4/Si/sub 4.4/B/sub 13.2/ were measured at room temperature and in the magnetic field range 0--15 kOe. For large magnetic field, three different functional dependences of magnetoresistance on magnetic field strength have been found as follows: (1) Δrho/rho approaches saturation. (2) Δrho/rho increases proportionally to H 2 . (3) For x = 0.15, a sharp Δrho/rho peak appears at a certain magnetic field strength in spatial angular orientation of both magnetic field and electric currents. Case (3) is a magnetic breakdown phenomenon. Magnetic breakdown occurs at the gap between the spin-up and spin-down sheets of the Fermi surface. This gap is the spin-orbit gap and its magnitude is a sensitive function of magnetization. Hence the magnitude and width of the magnetoresistance peak and the magnetic field strength at the peak point are functions of angular orientation of both magnetic field and electric current

  9. Corrosion-resistant amorphous metallic films of Mo49Cr33B18 alloy

    Science.gov (United States)

    Ramesham, R.; Distefano, S.; Fitzgerald, D.; Thakoor, A. P.; Khanna, S. K.

    1987-01-01

    Corrosion-resistant amorphous metallic alloy films of Mo49Cr33B18 with a crystallization temperature of 590 C were deposited onto glass and quartz substrates by magnetron sputter-quench technique. The amorphous nature of the films was confirmed by their diffuse X-ray diffraction patterns. The deposited films are densely packed (zone T) and exhibit low stress and good adhesion to the substrate. Corrosion current of as-deposited coating of MoCrB amorphous metallic alloy is approximately three orders of magnitude less than the corrosion current of 304 stainless steel in 1N H2SO4 solution.

  10. Study by positron annihilation of defects in metals, crystalline or amorphous alloys and in semiconductors

    International Nuclear Information System (INIS)

    Moumene, M.

    1984-07-01

    In this work lifetime of positron is used to study vacancies in different systems irradiated by electrons: pure metals (Fe, Zn), diluted (FeCo, FeAu) and concentrated (Cu 3 Au) alloys, semiconductors (CdTe, ZnTe) and amorphous alloys. Results on vacancy migration temperature and of the formation of two or three-dimensional vacancy clusters are given [fr

  11. Development of Computational Tools for Predicting Thermal- and Radiation-Induced Solute Segregation at Grain Boundaries in Fe-based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    Radiation-induced segregation (RIS) has been frequently reported in structural materials such as austenitic, ferritic, and ferritic-martensitic stainless steels (SS) that have been widely used in light water reactors (LWRs). RIS has been linked to secondary degradation effects in SS including irradiation-induced stress corrosion cracking (IASCC). Earlier studies on thermal segregation in Fe-based alloys found that metalloids elements such as P, S, Si, Ge, Sn, etc., embrittle the materials when enrichment was observed at grain boundaries (GBs). RIS of Fe-Cr-Ni-based austenitic steels has been modeled in the U.S. 2015 fiscal year (FY2015), which identified the pre-enrichment due to thermal segregation can have an important role on the subsequent RIS. The goal of this work is to develop thermal segregation models for alloying elements in steels for future integration with RIS modeling.

  12. Amorphous TM1−xBx alloy particles prepared by chemical reduction (invited)

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, Steen

    1991-01-01

    Amorphous transition-metal boron (TM-B) alloy particles can be prepared by chemical reduction of TM ions by borohydride in aqueous solutions. ln the last few years systematic studies of the parameters which control the composition, and, in turn, many of the properties of the alloy particles, have...... been performed and are reviewed in the present paper. The most important preparation parameters which influence the composition are the concentration of the borohydride solution and the pH of the TM salt solution. By controlling these parameters it is possible to prepare amorphous alloy samples...

  13. A Fundamental Approach to Developing Aluminium based Bulk Amorphous Alloys based on Stable Liquid Metal Structures and Electronic Equilibrium - 154041

    Science.gov (United States)

    2017-03-28

    AFRL-AFOSR-JP-TR-2017-0027 A Fundamental Approach to Developing Aluminium -based Bulk Amorphous Alloys based on Stable Liquid-Metal Structures and...to 16 Dec 2016 4.  TITLE AND SUBTITLE A Fundamental Approach to Developing Aluminium -based Bulk Amorphous Alloys based on Stable Liquid-Metal...Air Force Research Laboratory for accurately predicting compositions of new amorphous alloys specifically based on aluminium with properties superior

  14. Moessbauer and transport studies of amorphous and icosahedral Zr-Ni-Cu-Ag-Al alloys

    International Nuclear Information System (INIS)

    Stadnik, Z.M.; Rapp, O.; Srinivas, V.; Saida, J.; Inoue, A.

    2002-01-01

    The alloy Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 in the amorphous and icosahedral states, and the bulk amorphous alloy Zr 65 Al 7.5 Ni 10 Cu 7.5 Ag 10 , have been studied with 57 Fe Moessbauer spectroscopy, electrical resistance and magnetoresistance techniques. The average quadrupole splitting in both alloys decreases with temperature as T 3/2 . The average quadrupole splitting in the icosahedral alloy is the largest ever reported for a metallic system. The lattice vibrations of the Fe atoms in the amorphous and icosahedral alloys are well described by a simple Debye model, with the characteristic Moessbauer temperatures of 379(29) and 439(28) K, respectively. Amorphous alloys Zr 65 Al 7. )5Ni 10 Cu 7.5 Ag 10 and Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 have been found to be superconducting with the transition temperature, T c , of about 1.7 K. The magnitude of Tc and the critical field slope at Tc are in agreement with previous work on Zr-based amorphous superconductors, while the low-temperature normal state resistivity is larger than typical results for binary and ternary Zr-based alloys. The resistivity of icosahedral Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 is larger than that for the amorphous ribbon of the same composition, as inferred both from direct measurements on the ribbons and from the observed magnetoresistance. However the icosahedral sample is non-superconducting in the measurement range down to 1.5 K. The results for the resistivity and the superconducting T c both suggest a stronger electronic disorder in the icosahedral phase than in the amorphous phase. (author)

  15. Neutron diffraction studies of atomic structures of amorphous Fe-Ge and Ni-Ge alloys

    International Nuclear Information System (INIS)

    Yamada, Kazuyoshi; Endoh, Yasuo; Ishikawa, Yoshikazu; Watanabe, Noboru.

    1980-01-01

    The structures of Ge rich amorphous Fe-Ge and Ni-Ge alloys were studied by pulsed neutron total scattering. The partial structure factors of S sub(GeGe)(Q), S sub(NiGe)(Q) and S sub(NiNi)(Q) were determined successfully by using Ni 60 isotope for the Ni-Ge alloys. The Ge atoms in the 10 at% Ni-Ge amorphous alloy were found to construct a similar atomic structure as that of the amorphous Ge, while the intermediate short range order configuration between the tetrahedral random network (TRN) and the dense random packing (DRP) structure was found for the 30 at% Ni-Ge alloy. The Ge-Ge pair correlation for this intermediate short range order could well be reproduced by the modified Ge II microcrystalline model. (author)

  16. THE BEHAVIOR OF SOLUBLE METALS ELUTED FROM Ni/Fe-BASED ALLOY REACTORS AFTER HIGH-TEMPERATURE AND HIGH-PRESSURE WATER PROCESS

    Directory of Open Access Journals (Sweden)

    M. Faisal

    2012-05-01

    Full Text Available The behavior of heavy metals eluted from the wall of Ni/Fe-based alloy reactors after high-temperature and high-pressure water reaction were studied at temperatures ranging from 250 to 400oC. For this purpose, water and cysteic acid were heated in two reactor materials which are SUS 316 and Inconel 625. Under the tested conditions, the erratic behaviors of soluble metals eluted from the wall of Ni/Fe-based alloy in high temperature water were observed. Results showed that metals could be eluted even at a short contact time. The presence of air also promotes elution at sub-critical conditions. At sub-critical conditions, a significant amount of Cr was extracted from SUS 316, while only traces of Ni, Fe, Mo and Mn were eluted. In contrast, Ni was removed in significant amounts compared to Cr when Inconel 625 was tested. It was observed that eluted metals tend to increased under acidic conditions and most of those metals were over the limit of WHO guideline for drinking water. The results are significant both on the viewpoint of environmental regulation on disposal of wastes containing heavy metals, toxicity of resulting product and catalytic effect on a particular reaction.

  17. Structural, vibrational and optical studies on an amorphous Se90P10 alloy produced by mechanical alloying.

    Science.gov (United States)

    Oliveira, E C; Deflon, E; Machado, K D; Silva, T G; Mangrich, A S

    2012-03-21

    We investigated some physicochemical properties of an amorphous Se(90)P(10) alloy produced by mechanical alloying through x-ray diffraction, Raman spectroscopy, optical absorption spectroscopy and EXAFS techniques. The total structure factor obtained from x-ray diffraction and the EXAFS χ(k) oscillations on the Se K edge were used in reverse Monte Carlo simulations to obtain structural information such as average coordination numbers and interatomic distances and the distribution of structural units present in the alloy. In addition, we also determined the vibrational modes and the optical band gap energy of the alloy. © 2012 IOP Publishing Ltd

  18. Development of Ultra-high Purity (UHP) Fe-Based Alloys with High Creep and Oxidation Resistance for A-USC Technology

    Science.gov (United States)

    Hamdani, Fethi; Das, Nishith K.; Shoji, Tetsuo

    2018-03-01

    The design of ultra-high purity (UHP) Fe-based model alloys for advanced ultra-supercritical (A-USC) technology is attempted in this work. Creep testing has been performed in air at 700 °C and a stress level of 150 MPa. Analysis of the fracture surface and cross section of the crept specimen was performed. To evaluate the oxidation resistance in A-USC conditions, oxidation testing was performed in supercritical water (SCW) at 700 °C and 25 MPa. Weight gain (WG) measurements and meticulous characterization of the oxide scale were carried out. Based on thermodynamics and density functional theory calculations, some reactive elements in the Fe-Cr-Ni system were designated to promote precipitation strengthening and to improve the hydrogen-accelerated oxidation resistance. The addition of a 2 wt pct Mo into Fe-22Cr-22Ni-0.6Nb wt pct-based matrix did not significantly improve the creep resistance. The addition of 0.26 wt pct Zr coupled with cold working was effective for improving creep properties. The Mo-modified model alloy showed almost the same WG value as SUS310, while the Zr-modified alloy showed a higher WG value. Meanwhile, a Cr-enriched continuous oxide layer was formed at the oxidation front of the Zr-modified alloy and SUS310S after exposure to SCW conditions.

  19. Crystallization process of Fe80P20-xSix amorphous alloys

    International Nuclear Information System (INIS)

    Ohnuma, Masato; Sasaki, Osamu; Kuwano, Hisashi; Katano, Susumu; Morii, Yukio; Funahashi, Satoru; Child, H.R.; Hamaguchi, Yoshikazu.

    1993-01-01

    The crystallization process of Fe 80 P 20-x Si x amorphous alloys has been studied by electrical resistivity, X-ray diffraction, neutron diffraction, and transmission electron microscopy. This process is classified into two different patterns with a boundary of 6 at%Si. In the alloys containing less than 6 at%Si, α-Fe and Fe 3 P, both of which are stable phases, precipitate from the amorphous matrix directly. In the crystallization of the amorphous alloys containing over 6 at%Si, two complex phases are observed in the early stages. We found that these two phases are isostructural with the α-Mn type and β-Mn type phase. After these two metastable phases disappear, another metastable phase which is probably Fe 2 P appears. In the final stage of the crystallization, however, existing crystalline phases are stable α-Fe (or ordered Fe 3 Si) and Fe 3 P. In the isothermal crystallization process of the Fe 80 P 14 Si 6 amorphous alloy, only the α-Mn type phase is observed as the metastable phase at high temperatures such as 683, 703 and 723 K; however, at a lower temperature such as 668 K, no metastable phase is observed. The precipitation of the metastable α-Mn type and/or β-Mn type phases, which consist of the Frank-Kasper coordination polyhedra, can be closely related to the local structure in these amorphous alloys. (author)

  20. Effect Of Low-Temperature Annealing On The Properties Of Ni-P Amorphous Alloys Deposited Via Electroless Plating

    Directory of Open Access Journals (Sweden)

    Zhao Guanlin

    2015-06-01

    Full Text Available Amorphous Ni-P alloys were prepared via electroless plating and annealing at 200°C at different times to obtain different microstructures. The effects of low-temperature annealing on the properties of amorphous Ni-P alloys were studied. The local atomic structure of the annealed amorphous Ni-P alloys was analyzed by calculating the atomic pair distribution function from their X-ray diffraction patterns. The results indicate that the properties of the annealed amorphous Ni-P alloys are closely related to the order atomic cluster size. However, these annealed Ni-P alloys maintained their amorphous structure at different annealing times. The variation in microhardness is in agreement with the change in cluster size. By contrast, the corrosion resistance of the annealed alloys in 3.5 wt% NaCl solution increases with the decrease in order cluster size.

  1. Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Guo J.

    2015-06-01

    Full Text Available Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.

  2. Formation of soft magnetic high entropy amorphous alloys composites containing in situ solid solution phase

    Science.gov (United States)

    Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan

    2018-03-01

    Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.

  3. X-ray diffraction during study of short-range order in amorphous alloys (Review)

    International Nuclear Information System (INIS)

    Shelekhov, E.V.; Skakov, Yu.A.

    1988-01-01

    Conditions for amorphous solidification of metallic system many alloys have been investigated and material compositions with peculiar set of properties have been chosen due to the intensive researches, conducted recently. Amorphous alloys, which combine magnetically soft properties with high wear resistance, are used more extensively among these materials. Analysis of X-ray diffuse scattering by amorphous alloys, using diffractometer, is more available and popular in spite of the presence of energy-dispersion method and neutron diffraction analysis. It should be noted, that low-cost isotopes with neutrons scattering amplitude, which differs essentially from that of their natural mixture, do not exist for all these elements. That is why, it is necessary to use X-ray diffractometry to separate distribution partial functions as well

  4. Electron irradiation-induced nanocrystallization of amorphous Fe85B15 alloy: Evidence for athermal nature

    International Nuclear Information System (INIS)

    Qin, W.; Nagase, T.; Umakoshi, Y.

    2009-01-01

    Nanocrystallization of amorphous alloys induced by electronic energy deposition has been frequently reported in recent years. In this paper, the crystallization of amorphous Fe 85 B 15 alloy was performed by electron irradiation with 2 MeV electrons up to a flux of 4.0 x 10 24 m -2 s -1 . It was found that at 298 K, nanocrystalline Fe-B intermetallic phases formed prior to α-Fe phase, while at 463 K, only the α-Fe phase was observed. This phenomenon cannot be interpreted in terms of the electron-beam heating, but may be attributed to the irradiation-induced increases in the short-range order and atomic diffusivity. Theoretical analysis also showed that the maximum-temperature rise driven by beam heating is much lower than that required for thermal crystallization. Our work offers strong evidence that the irradiation-induced crystallization in amorphous alloys is not a thermal activation process

  5. AC susceptibility in amorphous and nanocrystalline Fe-Zr-B alloys

    International Nuclear Information System (INIS)

    Slawska-Waniewska, A.; Pont, M.; Lazaro, F.J.; Garcia, J.L.; Nowicki, P.; Munoz, J.S.

    1995-01-01

    AC susceptibility measurements show that in Fe 89 Zr 7 B 4 amorphous material the ferromagnetic-reentrant spin-glass transition follows the paramagnetic-ferromagnetic transition as the temperature is lowered, whereas the behavior of nanocrystalline sample is characteristic of ferromagnetic material. The results are interpreted in terms of a non-collinear magnetic structure in amorphous alloy which changes considerably after crystallization. ((orig.))

  6. 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)

  7. Electrical resistivity of amorphous Fesub(1-x) Bsub(x) alloys

    International Nuclear Information System (INIS)

    Paja, A.; Stobiecki, T.

    1984-07-01

    The concentration dependence of the electrical resistivity of amorphous Fesub(1-x) Bsub(x) alloys has been studied over a broad composition range. The measurements for RF sputtered films made in the liquid helium temperature have been analyzed in the framework of the diffraction model. The calculated results are in good agreement with the experimental data in the range of concentration 0.12< x <0.37 where samples are amorphous and have a metallic character. (author)

  8. Evidence of the extended orientational order in amorphous alloys obtained from magnetic measurements

    International Nuclear Information System (INIS)

    Chudnovsky, E.M.; Tejada, J.

    1993-01-01

    Magnetic measurements of R-Fe-B (R = rare earth) amorphous alloys show that magnetic anisotropy axes are correlated on the scale ∼ 100 A. The X-ray study of these materials does not reveal any positional correlations beyond the 10 A scale. These observations support theoretical suggestions that the orientational order in amorphous systems can be much more extended than the positional order. (orig.)

  9. Mechanical properties of amorphous alloys ribbons prepared by rapid quenching of the melt after different thermal treatments before quenching

    NARCIS (Netherlands)

    Tabachnikova, ED; Bengus, VZ; Egorov, D V; Tsepelev, VS; Ocelik, Vaclav

    1997-01-01

    The mechanical properties of amorphous alloy are greatly influenced by the thermal treatment of its melt before rapid quenching. The strength and the fracture toughness of some amorphous alloys obtained after melt beating above the melt critical temperature T-CR are essentially higher than those

  10. Amorphous phase formation in intermetallic Mg2Ni alloy synthesized by ethanol wet milling

    International Nuclear Information System (INIS)

    Wang, H.-W.; Chyou, S.-D.; Wang, S.-H.; Yang, M.-W.; Hsu, C.-Y.; Tien, H.-C.; Huang, N.-N.

    2009-01-01

    The hydriding/dehydriding properties of an intermetallic Mg 2 Ni alloy synthesized by wet ball milling in ethanol have been investigated. The appearance of the particle surface after different milling methods is one obvious difference. The alloyed powders prepared by either dry milling or wet milling under ethanol were characterized for phase content by X-ray diffractometer (XRD). The results show that two broad diffuse peaks, which are an ionic-organic-Mg amorphous material, appear in addition to the nickel element peaks. This unexpected amorphous phase has the special hydrogen absorbing/desorbing features.

  11. Crystal field symmetry and magnetic interactions in rare earth-silver amorphous alloys

    International Nuclear Information System (INIS)

    Pappa, Catherine.

    1979-01-01

    A study has been made of the following rare earth based amorphous alloys: Ndsub(x)Agsub(100-x), Prsub(x)Agsub(100-x), Gdsub(x)Agsub(100-x), Tlsub(x)Agsub(100-x). In rare earth based amorphous alloys, the symmetrical distribution of the crystal field is very wide and hence not very sensitive to the content of the alloys. The existence of preponderant negative magnetic interactions leads to an upset magnetic order, the magnetization of a small volume not being nil. The magnetic behaviour of alloys with a small concentration of rare earths is governed by the existence of clusters of statistical origin, within which a rare earth ion has at least one other rare earth ion in the position of first neighbour. The presence of a high anisotropy at low temperatures make the magnetic interactions between clusters inoperative [fr

  12. Comparison thermal and mechanical properties of two Zr-based bulk amorphous alloys

    International Nuclear Information System (INIS)

    Iqbal, M.; Akhtar, J.I.; Zhang, H.F.; Hu, Z.Q.

    2007-01-01

    Since the last decade bulk metallic glasses (BMGs) have attracted considerable attention of materials scientists due to their potential applications in various fields. In the present study, two alloys having composition (Zr/sub 64.5/ Ni/sub 15.5/ Al/sub 11.5/Cu/sub 8.5/)/sub 100-x/ Ti/sub x/ where x = 0 and 2, were synthesized using Cu mould casting technique from 2-3N pure elements. The alloys were designed following the Inoue's rules for amorphous alloys along with the criterion of conduction electrons/atom (e/a ratio =1.4) and average atomic size R/sub a/ = 0.1496 nm. Alloys were characterized by XRD, DSC and SEM/EDS and FESEM techniques. The alloys show wide supercooled liquid region and high GFA. Crystallization was studied and activation energies were calculated. Mechanical properties like Vicker's hardness, nanohardness elastic modulus and fracture strength etc. were measured. The alloys show high fracture strength of -2GPa. FESEM examination shows vein patterns and liquid droplets in the compression tested fractured samples in both the alloys. Shear angles were found to be 36+-1 degree and 38+-1 degree for alloy1 (base alloy with out Ti) and alloy2. Comparison of both alloys shows that Ti has positive effect of thermal and mechanical properties. It is concluded that the present alloys have very attractive mechanical and thermal properties. (author)

  13. Phase transformation during mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Amini, Rasool, E-mail: ramini2002@gmail.com [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Shamsipoor, Ali [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Ghaffari, Mohammad [Department of Electrical and Electronics Engineering, UNAM-National Institute of Materials Science and Nanotechnology Bilkent University, Ankara 06800 (Turkey); Alizadeh, Morteza [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Okyay, Ali Kemal [Department of Electrical and Electronics Engineering, UNAM-National Institute of Materials Science and Nanotechnology Bilkent University, Ankara 06800 (Turkey)

    2013-10-15

    Mechano-synthesis of Fe–32Mn–6Si alloy by mechanical alloying of the elemental powder mixtures was evaluated by running the ball milling process under an inert argon gas atmosphere. In order to characterize the as-milled powders, powder sampling was performed at predetermined intervals from 0.5 to 192 h. X-ray florescence analyzer, X-ray diffraction, scanning electron microscope, and high resolution transmission electron microscope were utilized to investigate the chemical composition, structural evolution, morphological changes, and microstructure of the as-milled powders, respectively. According to the results, the nanocrystalline Fe–Mn–Si alloys were completely synthesized after 48 h of milling. Moreover, the formation of a considerable amount of amorphous phase during the milling process was indicated by quantitative X-ray diffraction analysis as well as high resolution transmission electron microscopy image and its selected area diffraction pattern. It was found that the α-to-γ and subsequently the amorphous-to-crystalline (especially martensite) phase transformation occurred by milling development. - Graphical abstract: Mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si shape memory alloys in the powder form: amorphous phase formation, α-to-γ phase transformation, mechano-crystallization of the amorphous, and martensite phase formation during the process. Highlights: • During MA, the α-to-γ phase transformation and amorphization occurred. • Mechano-crystallization of the amorphous phase occurred at sufficient milling time. • The formation of high amount of ε-martensite was evidenced at high milling times. • The platelet, spherical, and then irregular particle shapes was extended by MA. • By MA, the particles size was increased, then reduced, and afterward re-increased.

  14. Structural transformations in amorphous ↔ crystalline phase change of Ga-Sb alloys

    International Nuclear Information System (INIS)

    Edwards, T. G.; Sen, S.; Hung, I.; Gan, Z.; Kalkan, B.; Raoux, S.

    2013-01-01

    Ga-Sb alloys with compositions ranging between ∼12 and 50 at. % Ga are promising materials for phase change random access memory applications. The short-range structures of two such alloys with compositions Ga 14 Sb 86 and Ga 46 Sb 54 are investigated, in their amorphous and crystalline states, using 71 Ga and 121 Sb nuclear magnetic resonance spectroscopy and synchrotron x-ray diffraction. The Ga and Sb atoms are fourfold coordinated in the as-deposited amorphous Ga 46 Sb 54 with nearly 40% of the constituent atoms being involved in Ga-Ga and Sb-Sb homopolar bonding. This necessitates extensive bond switching and elimination of homopolar bonds during crystallization. On the other hand, Ga and Sb atoms are all threefold coordinated in the as-deposited amorphous Ga 14 Sb 86 . Crystallization of this material involves phase separation of GaSb domains in Sb matrix and a concomitant increase in the Ga coordination number from 3 to 4. Results from crystallization kinetics experiments suggest that the melt-quenching results in the elimination of structural “defects” such as the homopolar bonds and threefold coordinated Ga atoms in the amorphous phases of these alloys, thereby rendering them structurally more similar to the corresponding crystalline states compared to the as-deposited amorphous phases

  15. Magnetic properties of FeZrB(Cu) amorphous alloys; the effect of boron content

    International Nuclear Information System (INIS)

    Slawska-Waniewska, A.; Zuberek, R.

    1996-01-01

    The composition dependences of the basic magnetic properties indicate that Fe-rich FeZrB(Cu) amorphous alloys show behavior characteristic of Invar material. The critical Fe concentration at which the ferromagnetic order disappears is found to be 98%. (orig.)

  16. Evidence of eutectic crystallization and transient nucleation in Al89La6Ni5 amorphous alloy

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Jiang, Jianzhong; Lin, Z. G.

    2001-01-01

    The phase evolution with the temperature and time in the process of crystallization of Al89La6Ni5 amorphous alloy has been investigated by in situ high-temperature and high-pressure x-ray powder diffraction using synchrotron radiation. Two crystalline phases, fcc-Al and a metastable bcc-(AlNi)(11...

  17. Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.

  18. Cu clustering stage before the crystallization in Fe-Si-B-Nb-Cu amorphous alloys

    DEFF Research Database (Denmark)

    Ohnuma, M.; Hono, K.; Onodera, H.

    1999-01-01

    The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary...

  19. Critical behavior of electrical resistivity in amorphous Fe–Zr alloys

    Indian Academy of Sciences (India)

    Electrical resistivity (ρ) of the amorphous (a-)Fe100-Zr ( = 8.5, 9.5 and 10) alloys has been measured in the temperature range 77 to 300 K, which embraces the second-order magnetic phase transition at the Curie temperature point . Analysis of the resistivity data particularly in the critical region reveals that these ...

  20. Comparison between Zr-Rh amorphous alloys fabricated by different processes

    International Nuclear Information System (INIS)

    Missell, F.P.

    1984-01-01

    It has been considered Zr-Rh amorphous alloys fabricated by sputtering and melt-spinning. For these materials, it was compared the superconducting transition temperatures T c , the superior critical field H c2 , the states density at Fermi energy N*, the dependence of T c with the hydrostatic pressure and results of differential thermic analysis. (A.C.A.S.) [pt

  1. Specimen thickness dependent crystallization of amorphous Ni69Cr14P17 alloy

    International Nuclear Information System (INIS)

    Schumacher, G.; Wahi, R.P.

    1994-01-01

    Metallic glasses are of technological interest due to their unique combination of physical properties, e.g. soft ferromagnetism, high ductility and large resistance to corrosion. Many interesting properties of metallic glasses improve or deteriorate, however, in the presence of even small fractions of crystalline phases. The basic understanding of the crystallization process is, therefore, important. The thermal stability of amorphous Ni 69 Cr 14 P 17 is of interest for the following reasons: (1) this alloy is being considered for use as joining material for structural components in fusion reactors, the chemical homogeneity and the high ductility of amorphous alloys are important process parameters of joining; (2) an amorphous alloy of similar composition, Ni 81 P 19 , was shown to reveal specimen thickness dependent crystallization. It is, however, not clear whether this phenomenon would also be observed in Ni 69 Cr 14 P 17 as even small additions of a third element can change the crystallization temperature and the crystallization process of an amorphous alloy

  2. Study of oxidation behaviour of Zr-based bulk amorphous alloy ...

    Indian Academy of Sciences (India)

    Unknown

    5Ni10Al7⋅5 has been studied in air environment at various temperatures in the temperature range 591–684 K using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy in the amorphous phase obeys the parabolic rate law ...

  3. Thermally induced crystallization of amorphous Fe40Ni40P14B6 alloy

    Czech Academy of Sciences Publication Activity Database

    Vasić, M.; Blagojević, V. A.; Begović, N. N.; Žák, Tomáš; Pavlović, V. B.; Minić, Dragica M.

    2015-01-01

    Roč. 614, AUG (2015), s. 129-136 ISSN 0040-6031 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Amorphous alloy * Crystallization * Kinetics * Deconvolution * Impingement * Surface morphology Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.938, year: 2015

  4. Crystallization processes in an amorphous Co-Fe-Cr-Si-B alloy under isothermal annealing

    Science.gov (United States)

    Fedorets, A. N.; Pustovalov, E. V.; Plotnikov, V. S.; Modin, E. B.; Kraynova, G. S.; Frolov, A. M.; Tkachev, V. V.; Tsesarskaya, A. K.

    2017-09-01

    Research present the crystallization processes investigation of the amorphous Co67Fe3Cr3Si15B12 alloy. In-situ experiments on heating in a transmission electron microscope (TEM) column were carried out. Critical temperatures influencing material structure are determined. The onset temperature of material crystallization was determined.

  5. Formation and structure of V-Zr amorphous alloy thin films

    KAUST Repository

    King, Daniel J M

    2015-01-01

    Although the equilibrium phase diagram predicts that alloys in the central part of the V-Zr system should consist of V2Zr Laves phase with partial segregation of one element, it is known that under non-equilibrium conditions these materials can form amorphous structures. Here we examine the structures and stabilities of thin film V-Zr alloys deposited at room temperature by magnetron sputtering. The films were characterized by X-ray diffraction, transmission electron microscopy and computational methods. Atomic-scale modelling was used to investigate the enthalpies of formation of the various competing structures. The calculations confirmed that an amorphous solid solution would be significantly more stable than a random body-centred solid solution of the elements, in agreement with the experimental results. In addition, the modelling effort provided insight into the probable atomic configurations of the amorphous structures allowing predictions of the average distance to the first and second nearest neighbours in the system.

  6. Corrosion-resistant amorphous alloy ribbons for electromagnetic filtration of iron rusts from water

    International Nuclear Information System (INIS)

    Kawashima, Asahi; Asami, Katsuhiko; Sato, Takeaki; Hashimoto, Koji

    1985-01-01

    An attempt was made to use corrosion-resistant amorphous Fe-9Cr-13P-7C alloy ribbons as an electromagnetic filter material for trapping various iron rusts suspended in water at 40 0 C. The ferrimagnetic Fe 3 O 4 rust was trapped with the 100 % efficiency and paramagnetic rusts such as α-Fe 2 O 3 , α-FeOOH and amorphous ferric oxyhydroxide were trapped with certain efficiencies at the magnetic field strength of 0.5-10 kOe. The regeneration of the filter by back-washing was easy. The trapping capacity of electromagnetic filter was proportional to the edge length of the filter material where the high magnetic field strength existed. Therefore, melt-spun thin and narrow amorphous alloy ribbons having the high corrosion resistance have the potential utility as electromagnetic filter material. (author)

  7. Surface morphology study of Zr-based amorphous alloys after immersion in boiling nitric acid medium

    Science.gov (United States)

    Sharma, Poonam; Dhawan, Anil; Sharma, S. K.

    2016-05-01

    Weight loss studies have been performed to determine the corrosion resistance of amorphous Zr60Nb2Al10Ni8Cu20 and Zr59Nb3Al10Ni8Cu20 alloys in aqueous HNO3 media at boiling temperature. The FESEM micrographs has been obtained to know the surface morphology of specimens after immersion in 11.5M boiling aqueous HNO3 media. Zr59Nb3Al10Ni8Cu20 alloy shows better corrosion resistance in nitric acid media than Zr60Nb2Al10Ni8Cu20 alloy.

  8. Local moments and electronic correlations in Fe-based Heusler alloys: Kα x-ray emission spectra measurements

    Energy Technology Data Exchange (ETDEWEB)

    Svyazhin, Artem, E-mail: svyazhin@imp.uran.ru [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Kurmaev, Ernst; Shreder, Elena; Shamin, Sergey [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Sahle, Christoph J. [ESRF – The European Synchrotron, CS40220, 38043 Grenoble Cedex 9 (France)

    2016-09-15

    Heusler alloys are a property-rich class of materials, intensively investigated today from both theoretical and real-world application points of view. In this paper, we attempt to shed light on the role of electronic correlations in the Fe{sub 2}MeAl group (where Me represents all 3d elements from Ti to Ni) of Heusler alloys. For this purpose, we have investigated the local moments of iron by means of the x-ray emission spectroscopy technique. To obtain numerical values of local moments, the Kα-FWHM method has been employed for the first time. In every compound of the group, the presence of a local moment on the Fe atom was detected. As has been revealed, the values of these moments are temperature-independent, pointing to an insufficiency of a pure itinerant approach to magnetism in these alloys. We also comprehensively compare the usage of Kβ main lines and Kα spectra as tools for the probing of local moments and point out the significant advantages of the latter. - Highlights: • Local spin moments of iron in Fe{sub 2}MeAl (Me = Ti … Ni) Heusler alloys were investigated by means of x-ray emission spectroscopy. • Independence of the local moments from temperature confirms their localized nature. • A local moment value of iron in Fe{sub 2}MeAl raises with the atomic number of element Me. • The applicability of the Kα x-ray emission line for extracting local moment values of 3d elements was established.

  9. Local moments and electronic correlations in Fe-based Heusler alloys: Kα x-ray emission spectra measurements

    International Nuclear Information System (INIS)

    Svyazhin, Artem; Kurmaev, Ernst; Shreder, Elena; Shamin, Sergey; Sahle, Christoph J.

    2016-01-01

    Heusler alloys are a property-rich class of materials, intensively investigated today from both theoretical and real-world application points of view. In this paper, we attempt to shed light on the role of electronic correlations in the Fe 2 MeAl group (where Me represents all 3d elements from Ti to Ni) of Heusler alloys. For this purpose, we have investigated the local moments of iron by means of the x-ray emission spectroscopy technique. To obtain numerical values of local moments, the Kα-FWHM method has been employed for the first time. In every compound of the group, the presence of a local moment on the Fe atom was detected. As has been revealed, the values of these moments are temperature-independent, pointing to an insufficiency of a pure itinerant approach to magnetism in these alloys. We also comprehensively compare the usage of Kβ main lines and Kα spectra as tools for the probing of local moments and point out the significant advantages of the latter. - Highlights: • Local spin moments of iron in Fe 2 MeAl (Me = Ti … Ni) Heusler alloys were investigated by means of x-ray emission spectroscopy. • Independence of the local moments from temperature confirms their localized nature. • A local moment value of iron in Fe 2 MeAl raises with the atomic number of element Me. • The applicability of the Kα x-ray emission line for extracting local moment values of 3d elements was established.

  10. Influence of Cr and Y Addition on Microstructure, Mechanical Properties, and Corrosion Resistance of SPSed Fe-Based Alloys

    Science.gov (United States)

    Muthaiah, V. M. Suntharavel; Mula, Suhrit

    2018-03-01

    Present work investigates the microstructural stability during spark plasma sintering (SPS) of Fe-Cr-Y alloys, its mechanical properties and corrosion behavior for its possible applications in nuclear power plant and petrochemical industries. The SPS was carried out for the Fe-7Cr-1Y and Fe-15Cr-1Y alloys at 800 °C, 900 °C, and 1000 °C due to their superior thermal stability as reported in Muthaiah et al. [Mater Charact 114:43-53, 2016]. Microstructural analysis through TEM and electron back scattered diffraction confirmed that the grain sizes of the sintered samples depicted a dual size grain distribution with >50 pct grains within a range of 200 nm and remaining grains in the range 200 nm to 2 µm. The best combination of hardness, wear resistance, and corrosion behavior was achieved for the samples sintered at 1000 °C. The high hardness (9.6 GPa), minimum coefficient of friction (0.25), and extremely low wear volume (0.00277 × 10-2 mm3) and low corrosion rate (3.43 mpy) are discussed in the light of solid solution strengthening, grain size strengthening, grain boundary segregation, excellent densification due to diffusion bonding, and precipitation hardening due to uniformly distributed nanosize Fe17Y2 phase in the alloy matrix. The SEM analysis of the worn surface and corroded features corroborated well with the wear resistance and corrosion behavior of the corresponding samples.

  11. Band gap tuning of amorphous Al oxides by Zr alloying

    DEFF Research Database (Denmark)

    Canulescu, Stela; Jones, N. C.; Borca, C. N.

    2016-01-01

    The optical band gap and electronic structure of amorphous Al-Zr mixed oxides, with Zr content ranging from4.8 to 21.9% were determined using vacuum ultraviolet (VUV) and X-ray absorption spectroscopy (XAS). Thelight scattering by the nano-porous structure of alumina at low wavelengths was estima...

  12. Macroscopic and microscopic magnetism of metal-metalloid amorphous alloys

    International Nuclear Information System (INIS)

    Vasconcellos, M.A.Z.; Fichtner, P.F.P.; Livi, F.P.; Costa, M.I. da; Baibich, M.N.

    1984-01-01

    In this paper is investigated the interrelation between macroscopic and microscopic magnetic phenomena using experimetnal data from Moessbauer effect and the magnetization of layers of amorphous (Fe 1-x Ni x ) 80 B 20 . The Moessbauer effect measurement show a distribution of hyperfine fields in Fe site as well as a likely distribution of isomeric shifts (M.W.O.) [pt

  13. Development of soft magnetic amorphous alloys with distinctly high Fe content

    Science.gov (United States)

    Chen, PingBo; Wang, AnDing; Zhao, ChengLiang; He, AiNa; Wang, Gang; Chang, ChunTao; Wang, XinMin; Liu, Chain-Tsuan

    2017-10-01

    This paper reports on the preparation of Fe82.7-85.7Si2-4.9B9.2-11.2P1.5-2.7C0.8 soft magnetic amorphous alloys with a distinctly high Fe content of 93.5-95.5 wt.% by component design and composition adjustment. All alloys can be readily fabricated into completely amorphous ribbon samples with good surface quality by the single copper roller melt-spinning method. These alloys show good bending ductility and excellent magnetic properties after annealing, i.e., low coercivity ( H c) of 3.3-5.9 A/m, high permeability ( μ e) of 5000-10000 and high flux saturation density ( B s) of 1.63-1.66 T. The mechanism of the good glass forming ability (GFA) and soft-magnetic properties are explored. The amorphous alloys with the high Fe content comparable to that of the desired high Si alloy can be promising candidates for the potential application in electric devices.

  14. Microstructure and surface chemistry of amorphous alloys important to their friction and wear behavior

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1986-01-01

    An investigation was conducted to examine the microstructure and surface chemistry of amorphous alloys, and their effects on tribological behavior. The results indicate that the surface oxide layers present on amorphous alloys are effective in providing low friction and a protective film against wear in air. Clustering and crystallization in amorphous alloys can be enhanced as a result of plastic flow during the sliding process at a low sliding velocity, at room temperature. Clusters or crystallines with sizes to 150 nm and a diffused honeycomb-shaped structure are produced on sizes to 150 nm and a diffused honeycomb-shaped structure are produced on the wear surface. Temperature effects lead to drastic changes in surface chemistry and friction behavior of the alloys at temperatures to 750 C. Contaminants can come from the bulk of the alloys to the surface upon heating and impart to the surface oxides at 350 C and boron nitride above 500 C. The oxides increase friction while the boron nitride reduces friction drastically in vacuum.

  15. Magneto-caloric effect of a Gd50Co50 amorphous alloy near the freezing point of water

    Directory of Open Access Journals (Sweden)

    L. Xia

    2015-09-01

    Full Text Available In the present work, we report the magneto-caloric effect (MCE of a binary Gd50Co50 amorphous alloy near the freezing temperature of water. The Curie temperature of Gd50Co50 amorphous ribbons is about 267.5 K, which is very close to room temperature. The peak value of the magnetic entropy change (-ΔSmpeak and the resulting adiabatic temperature rise (ΔTad. of the Gd50Co50 amorphous ribbons is much higher than that of any other amorphous alloys previously reported with a Tc near room temperature. On the other hand, although the -ΔSmpeak of Gd50Co50 amorphous ribbons is not as high as those of crystalline alloys near room temperature, its refrigeration capacity (RC is still much larger than the RC values of these crystalline alloys. The binary Gd50Co50 amorphous alloy provides a basic alloy for developing high performance multi-component amorphous alloys near room temperature.

  16. Mg amorphous alloys for biodegradable implants; Ligas amorfas de magnesio utilizadas em implantes consumiveis

    Energy Technology Data Exchange (ETDEWEB)

    Danez, G.P., E-mail: gabidanez@hotmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Koga, G.Y.; Tonucci, S.; Bolfarini, C.; Kiminami, C.S.; Botta Filho, W.J. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The use of implants made from amorphous alloys magnesium-based with additions of zinc and calcium are promising. Properties such as biocompatibility, low density, high mechanical strength, low modulus (as compared to alloys such as stainless steel and titanium), corrosion resistance and wear resistance make it attractive for use in implants. Moreover, the by-products of corrosion and wear are not toxic and may contribute to fixation. Aiming to understand the tendency of this amorphous ternary (Mg-Zn-Ca) and expand the information about this system, this work involved the use of the topological criterion of instability ({lambda}) and the criterion of electronegativity ({Delta}e) to the choice of compositions. The alloys were processed into wedge-shaped and analyzed structurally and in X-ray diffraction and scanning electron microscopy. (author)

  17. Structure and thermal stability of biodegradable Mg-Zn-Ca based amorphous alloys synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Moni Kanchan; Chou, Da-Tren; Hong, Daeho; Saha, Partha [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Chung, Sung Jae [Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Lee, Bouen [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Sirinterlikci, Arif [Department of Engineering, Robert Morris University, Moon Township, Pittsburgh, PA 15108 (United States); Ramanathan, Madhumati; Roy, Abhijit [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kumta, Prashant N., E-mail: matscib@gmail.com [Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2011-12-15

    Room temperature solid state diffusion reaction induced by mechanical alloying (MA) of elemental blends of Mg, Zn and Ca of nominal composition 60 at.% Mg-35 at.% Zn-5 at.% Ca has been studied. Formation of fully amorphous structure has been identified after 5 h of MA performed in a SPEX 8000M shaker mill, with milling continued up to 8 h to confirm the formation of homogeneous amorphous phase. Thermal stability of the amorphous phase has been studied using differential scanning calorimetry (DSC) and isothermal heat treatment at different temperatures. The amorphous powder consolidated using cold isostatic pressing (CIP) showed an envelope density {approx}80% of absolute density, which increased to an envelope density {approx}84% of absolute density after sintering at an optimized temperature of {approx}523 K for 9 h. Electrochemical bio-corrosion testing of the CIP compacted amorphous pellet as well as the sintered pellet performed in Dulbecco's Modified Eagle Medium, showed improved corrosion resistance in comparison to the as-cast pure Mg. Cytotoxicity testing of the CIP compacted amorphous pellet, performed using the MTT assay with MC3T3 osteoblastic cells, showed low cytotoxicity in comparison to the as-cast pure Mg.

  18. Influence of structural relaxation and partial devitrification on the corrosion resistance of Fe78B13Si9 amorphous alloy

    International Nuclear Information System (INIS)

    Souza, C.A.C.; Politi, F.S.; Kiminami, C.S.

    1998-01-01

    Amorphous alloys obtained by rapid solidification from the melt exhibit a similar structure to those observed in the liquid state, i.e., without long range ordering, in such a way that the constituents of the alloy usually are randomly and homogeneously distributed. Amorphous alloys, depending on their composition, may exhibit interesting characteristics such as very soft magnetic properties and improved resistance to corrosion. The high corrosion resistance of these alloys is attributed mainly to a higher rate of dissolution of passivating elements in the amorphous state. In addition, amorphous alloys are chemically homogeneous and free of defects such as grain boundaries, precipitates and segregation, which are favorable sites for corrosion. The corrosion resistance of amorphous alloys also depends on their thermal history. Several authors have reported that structural changes, such as structural relaxation and devitrification caused by annealing, change significantly the corrosion properties of these alloys. The purpose of this paper is to study corrosion resistance of the amorphous FeBSi alloy and the effects of structural changes such as structural relaxation and partial crystallization caused by annealing

  19. Invar behavior of NANOPERM-type amorphous Fe-(Pt)-Zr-Nb-Cu-B alloys

    Science.gov (United States)

    Gondro, J.; Świerczek, J.; Rzącki, J.; Ciurzyńska, W.; Olszewski, J.; Zbroszczyk, J.; Błoch, K.; Osyra, M.; Łukiewska, A.

    2013-09-01

    Transmission Mössbauer spectra of amorphous Fe86Zr7Nb1Cu1B5, Fe81Zr7Nb1Cu1B10 and Fe81Pt5Zr7Nb1Cu1B5 alloys in the as-quenched state and subjected to the accumulative annealing for 15 min in the temperature range from 573 K up to 750 K are presented. After these heat treatments the alloys remain in the amorphous state. The accumulative annealing for 15 min at 573 K and then 600 K of the Fe86Zr7Nb1Cu1B5 and Fe81Zr7Nb1Cu1B10 alloys causes the narrowing of the transmission Mössbauer spectra as compared to the as-quenched state and the decrease of the average hyperfine field induction which is connected with the invar effect. For similar behavior in Fe81Pt5Zr7Nb1Cu1B5 alloy the accumulative annealing up to 700 K is needed. With further increase of the annealing temperature up to 750 K the broadening of the Mössbauer spectra and the increase of the average hyperfine field induction occur. The lowest value of the average hyperfine field induction of amorphous samples is accompanied by the lowest value of the Curie temperature. The investigated amorphous alloys do not reach the magnetic saturation up to the magnetizing field of 2 T and the coefficient in Holstein-Primakoff term is about one order in magnitude larger than in other classical FeCo-based amorphous alloys due to the non-collinear magnetic structure. The Mössbauer spectra and hysteresis loops of the amorphous Fe86Zr7Nb1Cu1B5 alloy in the as-quenched state and after the accumulative annealing at 573+620 K for 15 min are sensitive to the tensile stresses subjected to the sample. Such behavior is ascribed to the invar anomalies.

  20. Understanding the magnetic anisotropy in Fe-Si amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, J.; Hamdan, N.M.; Jalil, P.; Hussain, Z.; Valvidares, S.M.; Alameda, J.M.

    2002-08-01

    The origin of the magnetic anisotropy in a very disordered Fe-Si alloy has been investigated. The alloy containing 40 percent at. Si was prepared in the form of a thin film in a DC magnetron sputtering chamber. Structural disorder was obtained from Extended X-ray Absorption Fine Structure spectroscopy. The uniformity and lack of inhomogeneities at a microscopic level was checked by measuring their transverse magnetic susceptibility and hysteresis loops. The orbital component of the magnetic moment was measured by X-ray Magnetic Circular Dichroism spectroscopy. The orbital moment was extraordinary high, 0.4mB. Such a high value contrasted with the relatively small uniaxial anisotropy energy of the thin film (2kJ/m3). This suggests that the cause of the magnetic anisotropy in this alloy was a small degree of correlation in the orientation of the local orbital moments along a preferential direction.

  1. Understanding the magnetic anisotropy in Fe-Si amorphous alloys

    International Nuclear Information System (INIS)

    Diaz, J.; Hamdan, N.M.; Jalil, P.; Hussain, Z.; Valvidares, S.M.; Alameda, J.M.

    2002-01-01

    The origin of the magnetic anisotropy in a very disordered Fe-Si alloy has been investigated. The alloy containing 40 percent at. Si was prepared in the form of a thin film in a DC magnetron sputtering chamber. Structural disorder was obtained from Extended X-ray Absorption Fine Structure spectroscopy. The uniformity and lack of inhomogeneities at a microscopic level was checked by measuring their transverse magnetic susceptibility and hysteresis loops. The orbital component of the magnetic moment was measured by X-ray Magnetic Circular Dichroism spectroscopy. The orbital moment was extraordinary high, 0.4mB. Such a high value contrasted with the relatively small uniaxial anisotropy energy of the thin film (2kJ/m3). This suggests that the cause of the magnetic anisotropy in this alloy was a small degree of correlation in the orientation of the local orbital moments along a preferential direction

  2. 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.)

  3. Magnetic properties of amorphous alloys of Fe with La, Lu, Y, and Zr

    International Nuclear Information System (INIS)

    Heiman, N.; Kazama, N.

    1979-01-01

    In order to study the systematics of the Fe-Fe exchange in amorphous rare-earth--Fe alloys, without the complications associated with the magnetic characteristics of the rare-earth elements, amorphous films of Fe alloyed with La, Lu, Y, and Zr have been prepared with a wide range of Fe concentrations. Magnetization and Moessbauer-effect measurements were made. The magnetic properties of the alloys depended critically on the choice of rare earth (or rare-earth-like element). YFe and LuFe alloys were found to have spin-glass characteristics while LaFe and ZrFe alloys were found to be ferromagnetic, but with evidence that exchange fluctuations were nearly as large as the average exchange. Thus the nature of the Fe-Fe exchange interaction depends critically upon the species of the rare earth. The most important parameter in determining the magnetic behavior of these alloys appears to be the size of the rare-earth atom, with large rare-earth atoms resulting in a smaller ratio of exchange fluctuations to exchange. The same dependence of the magnetic properties upon rare-earth size appears to be important in the case of magnetic-rare-earth atoms; however, the effect of rare-earth--Fe exchange also becomes important and these effects are discussed

  4. Microstructural investigation on marforming and conventional cold deformation in Ni-Ti-Fe-based shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Ritwik; Szpunar, Jerzy; Eskandari, Mostafa; Mohtadi-Bonab, M.A. [Univ. Saskatchewan, Dept. of Mechanical Engineering, Saskatoon (Canada)

    2015-08-15

    A hot-rolled Ni-Ti-Fe alloy was subjected to 50% cold rolling by laboratory rolling mill and was subsequently annealed at 800 C for 1.5 h. This sample was then deformed through another 10% reduction in thickness by two different routes (i) conventional cold rolling and (ii) marforming (rolling in liquid nitrogen) followed by annealing under identical conditions. The grain refinement during normal cold rolling was attributed to relatively large presence of dislocations in the ND // left angle 110 right angle grains in the starting microstructure. The regions of higher dislocation densities became gradually textured to ND // left angle 111 right angle orientation, with cold rolling. Marforming (deformation in liquid nitrogen following phase transformation) on the other hand led to more significant grain refinement and also change in the bulk texture. The objective of this study was to compare the grain refinement and microstructural modification produced through marforming with that obtained in conventional cold deformation.

  5. Hyperfine interactions and some thermomagnetic properties of amorphous FeZr(CrNbBCu alloys

    Directory of Open Access Journals (Sweden)

    Łukiewska Agnieszka

    2017-06-01

    Full Text Available In this research, we studied the magnetic phase transition by Mössbauer spectroscopy and using vibrating sample magnetometer for amorphous Fe86-xZr7CrxNb2Cu1B4 (x = 0 or 6 alloys in the as-quenched state and after accumulative annealing in the temperature range 600-750 K. The Mössbauer investigations were carried out at room and nitrogen temperatures. The Mössbauer spectra of the investigated alloys at room temperature are characteristic of amorphous paramagnets and have a form of asymmetric doublets. However, at nitrogen temperature, the alloys behave like ferromagnetic amorphous materials. The two components are distinguished in the spectrum recorded at both room and nitrogen temperatures. The low field component in the distribution of hyperfine field induction shifts towards higher field with the annealing temperature. It is assumed that during annealing at higher temperature, due to diffusion processes, the grains of α-Fe are created in the area corresponding to this component. Both investigated alloys show the invar effect and the decrease of hyperfine field induction after annealing at 600 K for 10 min is observed. It is accompanied by the lowering of Curie temperature.

  6. Amorphous CuZr alloy investigated by anomalous X-ray scattering

    International Nuclear Information System (INIS)

    Bionducci, M.; Buffa, F.; Licheri, G.; Navarra, G.

    1993-01-01

    Cu Zr amorphous powder was prepared by a mechano-chemical reaction in order to state a comparison with corresponding samples prepared by different amorphization processes. The structure of the alloyed powder is studied by anomalous X-ray scattering method. Starting from a suitable set of total and differential structure factors and using a regularization algorithm, a set of partial structure factors is obtained, which compares well with those previously obtained for a sample prepared by rapid solidification of the melt. (authors) 1 fig., 1 tab., 14 refs

  7. Corrosion resistance of amorphous and crystalline Pd40Ni40P20 alloys in aqueous solutions

    DEFF Research Database (Denmark)

    Wu, Y.F.; Chiang, Wen-Chi; Chu, J.

    2006-01-01

    The corrosion behaviors of amorphous and crystalline Pd40Ni40P20 alloys in various aqueous solutions are reported in this paper. The corrosion resistance of crystalline (annealed) Pd40Ni40P20 is better than that of amorphous Pd40Ni40P20 in various corrosive solutions, due to crystalline Pd40Ni40P20...... and mainly consists of inert Pd5P2, NI3P, Ni2Pd2P and noble Pd phases. These inert and noble properties result in a higher corrosion resistance in crystalline Pd40Ni40P20....

  8. Formation of amorphous Ti-50at.%Pt by solid state reactions during mechanical alloying

    CSIR Research Space (South Africa)

    Mahlatji, ML

    2013-10-01

    Full Text Available ) homogenous equiaxed particles MA of crystalline powder mixtures of two transition metals often results in the formation of amorphous alloys (Koch et al., 1983; Schwarz and Koch, 1986). It is generally accepted that this is due to solid-state amorphization...Ni (Schwarz, Petrich, and Saw, 1985; Liang, Wang, and Li, 1995) and TiPd (Thompson and Politis, 1987) systems. The deformation, fracturing, and cold welding of powder particles is illustrated by Figure 5(a-b), where the formerly spherical/-spongy particles...

  9. Investigation of inhomogeneous deformation in band amorphous alloys at constant heating rate

    Science.gov (United States)

    Fedorov, Victor; Berezner, Arseniy; Pluzhnikova, Tatiana; Beskrovnyi, Anatolyi

    2017-11-01

    The present paper contains investigations of the creep process in the cobalt-based amorphous metallic alloy within the temperature range from 300 up to 1023 K. In all the curves of deformation there were observed jumps and dying oscillations. It is noted that the creep of the sample ribbons is unstable and results in the thinning of ribbons with tightening and crimping. There is suggested the mechanism of inhomogeneous deformation, which takes place in course of the process of creep under intermittent heating. For the evaluation of amorphism in the treated samples there have been carried out neutron-graphical and X-ray diffraction investigations, as well as thermal analysis.

  10. Solid solution and amorphous phase in Ti–Nb–Ta–Mn systems synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzman, P. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Parra, C. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bejar, L. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Morelia C.P. 58000, Michoacán (Mexico); Medina, A. [Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, C.P. 58000, Michoacán (Mexico); Guzman, D. [Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó (Chile)

    2016-06-15

    This work discusses the formation of Ti–30Nb–13Ta–xMn (x: 2, 4 and 6 wt%) solid solution by mechanical alloying using a shaker mill. A solid solution was formed after 15 h of milling and an amorphous phase was formed after 30 h of milling, according to X-ray diffraction results. Disappearance of strongest X-ray diffraction peaks of Nb, Ta and Mn indicated the formation of solid solution, while, X-ray diffraction patterns of powders milled for 30 h showed an amorphous hump with crystalline peaks in the angular range of 35–45° in 2θ. TEM image analysis showed the presence of nanocrystalline intermetallic compounds embedded in an amorphous matrix. Mn{sub 2}Ti, MnTi and NbTi{sub 4} intermetallic compounds were detected and revealed crystallites with size ranging from 3 to 20 nm. The Gibbs free energy for the formation of solid solution and amorphous phase of three ternary systems (Ti–Nb–Ta, Ti–Nb–Mn and Ti–Ta–Mn) was calculated using extended Miedema's model. Experimental and thermodynamic data confirmed that solid solution was first formed in the alloy with 6wt% Mn followed by the formation of an amorphous phase as milling time increases. The presence of Mn promoted the formation of amorphous phase because the atomic radius difference between Mn with Ti, Nb and Ta. - Highlights: • Thermodynamics analysis of extension of solid solution of the Ti–Nb–Ta–Mn system. • Formation of amorphous phase and intermetallic compounds were observed. • Nanocrystalline intermetallic compounds were formed with the sizes between 3 and 20 nm.

  11. Invar behavior of NANOPERM-type amorphous Fe–(Pt)–Zr–Nb–Cu–B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gondro, J.; Świerczek, J., E-mail: swiercz@wip.pcz.pl; Rzącki, J.; Ciurzyńska, W.; Olszewski, J.; Zbroszczyk, J.; Błoch, K.; Osyra, M.; Łukiewska, A.

    2013-09-15

    Transmission Mössbauer spectra of amorphous Fe{sub 86}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5}, Fe{sub 81}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 10} and Fe{sub 81}Pt{sub 5}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5} alloys in the as-quenched state and subjected to the accumulative annealing for 15 min in the temperature range from 573 K up to 750 K are presented. After these heat treatments the alloys remain in the amorphous state. The accumulative annealing for 15 min at 573 K and then 600 K of the Fe{sub 86}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5} and Fe{sub 81}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 10} alloys causes the narrowing of the transmission Mössbauer spectra as compared to the as-quenched state and the decrease of the average hyperfine field induction which is connected with the invar effect. For similar behavior in Fe{sub 81}Pt{sub 5}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5} alloy the accumulative annealing up to 700 K is needed. With further increase of the annealing temperature up to 750 K the broadening of the Mössbauer spectra and the increase of the average hyperfine field induction occur. The lowest value of the average hyperfine field induction of amorphous samples is accompanied by the lowest value of the Curie temperature. The investigated amorphous alloys do not reach the magnetic saturation up to the magnetizing field of 2 T and the coefficient in Holstein–Primakoff term is about one order in magnitude larger than in other classical FeCo-based amorphous alloys due to the non-collinear magnetic structure. The Mössbauer spectra and hysteresis loops of the amorphous Fe{sub 86}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5} alloy in the as-quenched state and after the accumulative annealing at 573+620 K for 15 min are sensitive to the tensile stresses subjected to the sample. Such behavior is ascribed to the invar anomalies. - Highlights: • Complex magnetic transformations found in the amorphous Fe{sub 86}Zr{sub 7}Nb{sub 1}Cu{sub 1}B{sub 5}, Fe{sub 81}Zr{sub 7}Nb{sub 1}Cu{sub 1}B

  12. Radiation resistance of amorphous silicon alloy solar cells

    International Nuclear Information System (INIS)

    Hanak, J.J.; Chen, E.; Myatt, A.; Woodyard, J.R.

    1987-01-01

    The radiation resistance of a-Si alloy solar cells when bombarded by high energy particles is reviewed. The results of investigations of high energy proton radiation resistance of a-Si alloy thin film photovoltaic cells are reported. Irradiations were carried out with 200 keV and 1.00 MeV protons with fluences ranging betweeen 1E11 and 1E15 cm-2. Defect generation and passivation mechanisms were studied using the AM1 conversion efficiency and isochronal anneals. It is concluded that the primary defect generation mechanism results from the knock-on of Si and Ge in the intrinsic layer of the cells. The defect passivation proceeds by the complex annealing of Si and Ge defects and not by the simple migration of hydrogen

  13. New aspect of ultrasonic detection of some significant structural parameters of amorphous Se-Te alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kostial, P.; Malik, L. (Technical Univ. of Transport and Communication Engineering, Zilina (Czechoslovakia)); Both, L. (Meopta, Bratislava (Czechoslovakia))

    1983-12-16

    Measurements of the ultrasonic attenuation and transit time as a function of temperature in amorphous Se/sub 1-x/Te/sub x/ alloys (x = 1, 3, 10, and 20 at%) are made. There is a remarkable change in the slope of the ultrasonic transit time curve at 31 /sup 0/C (T/sub 1/) and a corresponding maximum in ultrasonic attenuation. The point T/sub 1/ is independent of the Te concentration. The second point T/sub 2/ found from curves shifts to higher temperatures with increase of the Te content. T/sub 2/ is identified as glass transition point of the alloy.

  14. Polarization and resistivity measurements of post-crystallization changes in amorphous Fe-B-Si alloys

    International Nuclear Information System (INIS)

    Chattoraj, I.; Bhattamishra, A.K.; Mitra, A.

    1993-01-01

    The effects of grain growth and compositional changes on the electrochemical behavior and the resistivity of amorphous iron-boron-silicon (Fe 77.5 B 15 Si 7.5 ) alloys after crystallization were studied. Deterioration of the protective passive film was observed, along with increased annealing. Potentiodynamic polarization provided excellent information about microstructural and chemical changes. It was concluded that electrochemical measurements could be used in conjunction with resistivity measurements in direct studies of grain growth and chemical changes occurring in different phases of the devitrified alloy

  15. High-resolution transmission electron microscopy of grain-refining particles in amorphous aluminum alloys

    International Nuclear Information System (INIS)

    Schumacher, P.; Greer, A.L.

    1996-01-01

    The nucleation mechanism of Al-Ti-B grain refiners is studied in an Al-based amorphous alloy. The ability to limit growth of α-Al in the amorphous alloy permits the microscopical observation of nucleation events on boride particles. Earlier studies of this kind are extended by using high-resolution electron microscopy. This shows that the efficient nucleation α-Al depends on the TiB 2 particles being coated with a thin layer of Al 3 Ti, which can form only when there is some excess titanium in the melt. The aluminide layer, stabilized by adsorption effects, can be as little as a few monolayers thick, and is coherent with the boride. The nature of this layer, and its importance for the nucleation mechanism are discussed. The fading of the grain refinement action is also considered

  16. A non-resonant RF cavity loaded with amorphous alloy for proton cancer therapy

    CERN Document Server

    Makita, Y; Nayayama, T; Tsuchidate, H; Tsukishima, C; Yoshida, K

    1999-01-01

    A non-resonant RF cavity loaded with amorphous alloy cores has been designed and tested. The cavity has a re-entrant structure loaded with 8 amorphous alloy toroidal core and its characteristic impedance is designed as 450 Omega . The RF power is fed by 1 kW solid state amplifier using a step-up transformer with 1:9 impedance ratio. In the high power test, an accelerating gap voltage of more than 900 V was measured with input power of 1 kW in the frequency range of 1 to 10 MHz. The voltage standing wave ratio (VSWR) was less than 2.0. The results prove that the cavity may be used successfully within a compact proton synchrotron for a cancer therapy facility. (3 refs).

  17. 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

  18. Surface effects on Sm valence in amorphous Sm alloys

    International Nuclear Information System (INIS)

    Krill, G.; Durand, J.; Berrada, A.; Hassanain, N.; Ravet, M.F.

    1980-01-01

    The results are presented of XPS and X-ray absorption measurements performed on amorphous Sm Au and La Sm Au compounds. The XPS Sm 3dsub(5/2) core level spectra in these compounds reveal that at the surface (5 to 7 A) the samarium ions present both the Sm 2+ (4f 6 ) and Sm 3+ (4f 5 ) configurations. When the concentration in samarium decreases it is shown that the Sm 2+ configuration is strongly enhanced at the surface whereas the X-ray absorption measurements indicate on the contrary that in the bulk only the Sm 3+ configuration is present. Comparison is made with similar findings in pure crystalline Sm and various crystalline rare earth compounds. (author)

  19. Optimization of operational parameters and bath control for electrodeposion of Ni-Mo-B amorphous alloys

    OpenAIRE

    Marinho,Fabiano A.; Santana,François S. M.; Vasconcelos,André L. S.; Santana,Renato A. C.; Prasad,Shiva

    2002-01-01

    Optimization of operational parameters of an electrodeposition process for deposition of boron-containing amorphous metallic layer of nickel-molybdenum alloy onto a cathode from an electrolytic bath having nickel sulfate, sodium molybdate, boron phosphate, sodium citrate, sodium-1-dodecylsulfate and ammonia for pH adjustments to 9.5 has been studied. Detailed studies of the efects on bath temperature, mechanical agitation, cathode current density and anode format have led to optimum operation...

  20. Structural transformations of Fe81B13Si4C2 amorphous alloy induced by heating

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica M.; Minić, Dušan M.; Žák, Tomáš; Roupcová, Pavla; David, Bohumil

    2011-01-01

    Roč. 323, č. 5 (2011), s. 400-404 ISSN 0304-8853 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : Amorphous material * Metallic glass * Metal and alloy * Phase transition * Thermal analysis * Mössbauer spectrum * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.780, year: 2011

  1. Effects of thermal relaxation on an amorphous superconducting Zr--Rh alloy

    International Nuclear Information System (INIS)

    Drehman, A.J.; Johnson, W.L.

    1978-05-01

    The electronic and superconducting properties of an amorphous transition metal alloy are used to evaluate the effects of low temperature annealing. It is observed that the superconducting transition temperature and the electrical resistivity relax exponentially in time from their initial value to a final relaxed value. From this an activation energy for the relaxation process is derived and an explanation is suggested which involves internal stress

  2. Directional and short-range ordering kinetics in metallic alloys, crystalline and amorphous

    International Nuclear Information System (INIS)

    Hillairet, J.

    1985-01-01

    This presentation describes the methods (resistometric and anelastic) based on analysis of stress-induced directional ordering and short-range ordering and their application to the study of metallic alloys, crystalline and amorphous. It focuses on the determination of the atomic mobility and point defect properties. It discusses also the structural information which can be gained by Zener relaxation studies about the order-disorder transition and self-induced directional ordering phenomena

  3. Amorphous Alloy Membranes Prepared by Melt-Spin methods for Long-Term use in Hydrogen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Dhanesh; Kim, Sang-Mun; Adibhatla, Anasuya; Dolan, Michael; Paglieri, Steve; Flanagan, Ted; Chien, Wen-Ming; Talekar, Anjali; Wermer, Joseph

    2013-02-28

    Amorphous Ni-based alloy membranes show great promise as inexpensive, hydrogenselective membrane materials. In this study, we developed membranes based on nonprecious Ni-Nb-Zr alloys by adjusting the alloying content and using additives. Several studies on crystallization of the amorphous ribbons, in-situ x-ray diffraction, SEM and TEM, hydrogen permeation, hydrogen solubility, hydrogen deuterium exchange, and electrochemical studies were conducted. An important part of the study was to completely eliminate Palladium coatings of the NiNbZr alloys by hydrogen heattreatment. The amorphous alloy (Ni0.6Nb0.4)80Zr20 membrane appears to be the best with high hydrogen permeability and good thermal stability.

  4. Surface crystallization and magnetic properties of amorphous Fe80B20 alloy

    International Nuclear Information System (INIS)

    Vavassori, P.; Ronconi, F.; Puppin, E.

    1997-01-01

    We have studied the effects of surface crystallization on the magnetic properties of Fe 80 B 20 amorphous alloys. The surface magnetic properties have been studied with magneto-optic Kerr measurements, while those of bulk with a vibrating sample magnetometer. This study reveals that surface crystallization is similar to the bulk process but occurs at a lower temperature. At variance with previous results on other iron-based amorphous alloys the surface crystalline layer does not induce bulk magnetic hardening. Furthermore, both the remanence to saturation ratio and the bulk magnetic anisotropy do not show appreciable variations after the formation of the surface crystalline layer. The Curie temperature of the surface layer is lower with respect to the bulk of the sample. These effects can be explained by a lower boron concentration in the surface region of the as-cast amorphous alloy. Measurements of the chemical composition confirm a reduction of boron concentration in the surface region. copyright 1997 American Institute of Physics

  5. Nanocrystallization in spark plasma sintered Fe{sub 48}Cr{sub 15}Mo{sub 14}Y{sub 2}C{sub 15}B{sub 6} bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashish; Harimkar, Sandip P. [School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, Oklahoma 74078 (United States); Katakam, Shravana; Dahotre, Narendra B. [Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203 (United States); Ilavsky, Jan [Advanced Photon Source, Argonne National Laboratory, Chicago, Illinois 60439 (United States)

    2013-08-07

    Spark plasma sintering (SPS) is evolving as an attractive process for the processing of multi-component Fe-based bulk amorphous alloys and their in-situ nanocomposites with controlled primary nanocrystallization. Extended Q-range small angle neutron scattering (EQ-SANS) analysis, complemented by x-ray diffraction and transmission electron microscopy, was performed to characterize nanocrystallization behavior of SPS sintered Fe-based bulk amorphous alloys. The SANS experiments show significant scattering for the samples sintered in the supercooled region indicating local structural/compositional changes associated with the profuse nucleation of nanoclusters (∼4 nm). For the samples spark plasma sintered near and above crystallization temperature (>653 °C), the SANS data show the formation of interference maximum indicating the formation and growth of (Fe,Cr){sub 23}C{sub 6} crystallites. The SANS data also indicate the evolution of bimodal crystallite distribution at higher sintering temperatures (above T{sub x1}). The growth of primary nanocrystallites results in impingement of concentration gradient fields (soft impingement effect), leading to non-random nucleation of crystallites near the primary crystallization.

  6. Materials developed by mechanical alloying and melt spinning

    OpenAIRE

    Suñol Martínez, Joan Josep; Fort, Joaquim

    2008-01-01

    Materials science is a multidisciplinary research topic related to the development of physics and technology. Mechanical alloying of ribbon flakes is a two steps route to develop advanced materials. In this work, a Fe based alloy was obtained using three pathways: mechanical alloying, melt-spinning and mechanical alloying of previously melt-spun samples. Processing conditions allow us to obtain amorphous or nanocrystalline structures. Furthermore, a bibliographic revision of mechanical al...

  7. Band gap tuning of amorphous Al oxides by Zr alloying

    Energy Technology Data Exchange (ETDEWEB)

    Canulescu, S., E-mail: stec@fotonik.dtu.dk; Schou, J. [Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde (Denmark); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Borca, C. N.; Piamonteze, C. [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Rechendorff, K.; Nielsen, L. P.; Almtoft, K. P. [Danish Technological Institute, Kongsvang Alle 29, 8000 Aarhus (Denmark); Gudla, V. C.; Bordo, K.; Ambat, R. [Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs-Lyngby (Denmark)

    2016-08-29

    The optical band gap and electronic structure of amorphous Al-Zr mixed oxides with Zr content ranging from 4.8 to 21.9% were determined using vacuum ultraviolet and X-ray absorption spectroscopy. The light scattering by the nano-porous structure of alumina at low wavelengths was estimated based on the Mie scattering theory. The dependence of the optical band gap of the Al-Zr mixed oxides on the Zr content deviates from linearity and decreases from 7.3 eV for pure anodized Al{sub 2}O{sub 3} to 6.45 eV for Al-Zr mixed oxides with a Zr content of 21.9%. With increasing Zr content, the conduction band minimum changes non-linearly as well. Fitting of the energy band gap values resulted in a bowing parameter of ∼2 eV. The band gap bowing of the mixed oxides is assigned to the presence of the Zr d-electron states localized below the conduction band minimum of anodized Al{sub 2}O{sub 3}.

  8. Contribution to diffusion mechanism study in amorphous metallic alloys

    International Nuclear Information System (INIS)

    Delaye, Jean-Marc

    1993-01-01

    This work is dedicated to the study of the vacancy diffusion mechanism in mono-elementary and binary amorphous Lennard-Jones systems, by a molecular dynamics method. The first chapter is a review of the preceding works performed before the beginning of this thesis, the method of simulation is described in the second chapter. We showed in the following chapters that the vacancies, introduced by the removal of one atom, remain stable on a large percentage of sites, especially in the binary system. By calculating some thermodynamical values, formation and migration enthalpies and entropies, we showed that the vacancy mechanism is magnified in a disordered system, as compared to a crystal of the same composition, and therefore can explain the magnitudes of the experimental diffusion coefficients. In parallel, to measure diffusion coefficients, we have settled an experimental method based on the evolution of the resistivity of a multilayer sample during interdiffusion, a gold-silver multilayer in our case (chapter six). By measurements under pressure, the activation volume is determined and our results agree well with the preceding ones. (author) [fr

  9. Crystallization Process of Heat-treated Amorphous Ni-P Alloy Coating

    Directory of Open Access Journals (Sweden)

    JIN Shi-wei

    2016-09-01

    Full Text Available Amorphous Ni-P alloy coatings were prepared on 45 carbon steel blocks using electrodeposition method. The thermal effect and quality change of Ni-P alloy coating under heating rate of 20℃/min were analyzed by differential scanning calorimetry (DSC and thermogravimetry (TG. Coatings were heat-treated at 300℃ and 400℃ for 0, 15, 30, 45, 60, 75min respectively, coating surface was characterized by scanning electron microscope (SEM, energy dispersive spectrometer (EDS, X-ray diffraction (XRD, microhardness tester. The result shows that the exothermic peak of Ni-P alloy coating appears at 284.8℃, coating quality and elemental composition are stable during the heat treatment. Crystallization process experiences a transformation of amorphous, metastable state NiP and Ni5P2, stable state Ni3P. The microhardness of coating can be improved remarkably after heat treatment, namely, the maximum value of heat-treated coating is 1036.56HV, which is nearly 2 times as hard as as-deposited coating. The corrosion resistance of heat-treated Ni-P alloy coating in NaCl solution is inferior to as-deposited coating, but they are both much better than 45 carbon steel substrate.

  10. Study of Critical Behavior in Amorphous Fe85Sn5Zr10 Alloy Ribbon

    Science.gov (United States)

    Han, L. A.; Hua, X. H.; Zhu, H. Z.; Yang, J.; Yang, H. P.; Yan, Z. X.; Zhang, T.

    2017-02-01

    We have investigated the critical behavior in amorphous Fe85Sn5Zr10 alloy ribbon prepared using a single-roller melt-spinning method. This alloy shows a second-order magnetic transition from paramagnetic to ferromagnetic (FM) state at the Curie temperature T C (˜306 K). To obtain more information on the features of the magnetic transition, a detailed critical exponent study was carried out using isothermal magnetization M ( H, T) data in the vicinity of the T C. Modified Arrott plot, Kouvel-Fisher plot, Widom's scaling relation and critical isotherm analysis techniques were used to investigate the critical behavior of this alloy system around its phase transition point. The values of critical exponents determined using the above methods are self-consistent. The estimated critical exponents are fairly close to the theoretical prediction of the three-dimensional (3D) Heisenberg model, implying that short-range FM interactions dominate the critical behavior in amorphous Fe85Sn5Zr10 alloy ribbon.

  11. Effect of chromium and phosphorus on the physical properties of iron and titanium-based amorphous metallic alloy films

    Science.gov (United States)

    Distefano, S.; Rameshan, R.; Fitzgerald, D. J.

    1991-01-01

    Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. Some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique are reported. The films were characterized using differential scanning calorimetry, stress analysis, SEM, XRD, SIMS, electron microprobe, and potentiodynamic polarization techniques.

  12. Optimization of operational parameters and bath control for electrodeposion of Ni-Mo-B amorphous alloys

    Directory of Open Access Journals (Sweden)

    Marinho Fabiano A.

    2002-01-01

    Full Text Available Optimization of operational parameters of an electrodeposition process for deposition of boron-containing amorphous metallic layer of nickel-molybdenum alloy onto a cathode from an electrolytic bath having nickel sulfate, sodium molybdate, boron phosphate, sodium citrate, sodium-1-dodecylsulfate and ammonia for pH adjustments to 9.5 has been studied. Detailed studies of the efects on bath temperature, mechanical agitation, cathode current density and anode format have led to optimum operational conditions for obtaining satisfactory alloy deposits. The highest cathode current efficiency for deposition of the alloy was about 69% for cylindrical and 64% for rectangular platinum anode while working at bath temperature 80ºC, cathode rotation 15 rpm and cathode current density 100 mA cm-2. A voltammetric method for automatic monitoring and control of the process was proposed.

  13. Remanent magnetization of amorphous La--Gd--Au alloys with high Gd content

    Energy Technology Data Exchange (ETDEWEB)

    Poon, S.J.; Durand, J.

    1977-04-01

    Results of bulk magnetic measurements are reported for splat-cooled amorphous alloys (La/sub 100-x/Gd/sub x/)/sub 80/Au/sub 20/ over the concentrated region between the dilute (x less than or equal to 1 at.%) and the ferromagnetic range (x > 70 at.%). For x less than or equal to 40 at.% alloys, low field susceptibility maxima occur at temperatures proportional to x, and the reduced remanent magnetization M/sub rs/(T)/x depends only on the reduced temperature T/x. Our results are analyzed in the spirit of a phenomenological model of uncompensated magnetic clouds. The interplay of the RKKY interaction and of the anisotropic dipolar forces is sufficient to account for the order of magnitude of the remanent magnetization for x less than or equal to 40 alloys.

  14. Control and optimization of baths for electrodeposition of Co-Mo-B amorphous alloys

    Directory of Open Access Journals (Sweden)

    S. Prasad

    2000-12-01

    Full Text Available Optimization and control of an electrodeposition process for depositing boron-containing amorphous metallic layer of cobalt-molybdenum alloy onto a cathode from an electrolytic bath having cobalt sulfate, sodium molybdate, boron phosphate, sodium citrate, 1-dodecylsulfate-Na, ammonium sulfate and ammonia or sulfuric acid for pH adjustments has been studied. Detailed studies on bath composition, pH, temperature, mechanical agitation and cathode current density have led to optimum conditions for obtaining satisfactory alloy deposits. These alloys were found to have interesting properties such as high hardness, corrosion resistance, wear resistance and also sufficient ductility. A voltammetric method for automatic monitoring and control of the process has been proposed.

  15. Low-emissivity coating of amorphous diamond-like carbon/Ag-alloy multilayer on glass

    International Nuclear Information System (INIS)

    Chiba, Kiyoshi; Takahashi, Toshiyuki; Kageyama, Takashi; Oda, Hironori

    2005-01-01

    Transparent low-emissivity (low-e) coatings comprising dielectrics of amorphous diamond-like carbon (DLC) and Ag-alloy films are investigated. All films have been prepared by dc magnetron sputtering. An index of refraction of the DLC film deposited in a gas mixture of Ar/H 2 (4%) shows n = 1.80 + 0.047i at 500 nm wavelength. A multilayer stack of DLC (70 nm thick)/Ag 87.5 Cu 12.5 -alloy (10 nm)/DLC (140 nm)/Ag 87.5 Cu 12.5 -alloy (10 nm)/DLC (70 nm) has revealed clear interference spectra with spectra selectivity. This coating performs low emittance less than 0.1 for black body radiation at 297 K, exhibiting a transparent heat mirror property embedded in DLC films

  16. Structural order and magnetism of rare-earth metallic amorphous alloys

    International Nuclear Information System (INIS)

    Maurer, M.

    1984-01-01

    Local symmetry (as evaluated from the electric field gradient tensor) and radial distribution functions (obtained by EXAFS measurement) are determined in a series of amorphous rare-earth base alloys. Local order is found to increase with the extent of heteroatomic interactions. Various magnetic phases (including ferromagnetic, spin-glass, reentrant spin-glass) occur for europium alloys with simple metals (Mg, Zn, Cd, Al, Au, ...). This variety reflects the sensitivity of exchange interactions to the presence of non-s conduction electrons. Asperomagnetic structures are established for the Dy alloys. The crystalline electric field interactions at the Dy 3+ ions are interpreted with the help of local symmetry data. Quadratic axial and non-axial crystal field terms are sufficient and necessary in order to account for the hyperfine and bulk experimental results [fr

  17. Corrosion study of Fe-based bulk metallic glasses in chloride medium

    International Nuclear Information System (INIS)

    Waqas, M.U.

    2010-01-01

    Bulk metallic glasses (amorphous metals) are an emerging class of alloys due to their unique set of properties. They exhibit excellent mechanical strength, high hardness and corrosion resistance. Unlike other new materials, which are developed to fulfill a particular need, BMGs came to existence without any application, so the uses of BMGs are yet to be exploited. Before putting BMGs into applications, their properties must be fully understood, particularly the corrosion resistance against a working environment. Fe-based amorphous alloys are particularly important for their future use as structural materials due to their high strength and cheap raw materials. Some Fe-based amorphous alloys exhibit excellent soft magnetic properties, which make them feasible to be used as transformer materials. Some compositions are also competitive to replace the existing bio-materials like 316L SS due to their better biocompatibility. Fe-based amorphous alloys can also be used as thermal-spray coatings due to their unchanged corrosion resistance as compared to bulk alloy. Many electrochemical studies have been done to investigate the corrosion resistance of Fe- based BMG that showed its excellent corrosion resistance. Still not enough data is available and further work is needed to be done in this field. In the present study, corrosion of Fe/sub 50/Cr/sub 14/Mo/sub 14/C/sub 14/B/sub 6/X/sub 2/ (X = Y, Gd, and Dy), designated as S1, S2 and S3 respectively, was investigated in 4M NaCI solution. The corrosion study was done using potentiodynamic polarization test and accelerated corrosion test at a current density of 6mA.cm/sup -2/. Following this; corrosion morphology was investigated by scanning electron microscope, while compositional analysis was done by energy dispersive x-ray spectroscope (EDX) attached with SEM. S1 and S3 showed similar corrosion behavior with S3 having the highest corrosion resistance while S2 have different corrosion behavior as well as least corrosion

  18. Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

    DEFF Research Database (Denmark)

    Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.

    2000-01-01

    Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial...... measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (Hv) of the amorphous material for y = 2% is higher (similar to 360 kg/mm(2)) than for y = 0 (similar to 290 kg/mm(2)). On crystallisation the hardness of the latter material increases to the 400 kg/mm(2) level...

  19. 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.

  20. 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.

  1. Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance

    Science.gov (United States)

    Kikuci, M.; Fukamichi, K.; Masumoto, T.

    1987-01-01

    Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

  2. Correlation of electrical transport and magnetism in amorphous Mn-B alloys

    Science.gov (United States)

    Bryden, W. A.; Morgan, J. S.; Kistenmacher, T. J.; Moorjani, K.

    1987-04-01

    X-ray scattering, magnetism, and electrical transport studies on amorphous thin films of MnxB100-x alloys with x=52 and 48 are reported. Each alloy exhibits a low-field (5 G) static susceptibility peak (10 K, x=52; 16 K, x=48) associated with a spin-glass transition. Isothermal magnetization data (6 K) are analyzed within the random anisotropy model of Chudnovsky, Saslow, and Serota. The magnetization isotherm for the x=52 alloy is dominated at high fields (>24 kG) by field-induced moments, while for x=48 a term (αH-1/2) arising from a ferromagnet with a wandering axis prevails to the highest field strength (44 kG). Initially the electrical resistance for these Mn-B alloys decreases monotonically with decreasing temperature, reaching a minimum (Tm) at 22 K (x=52) and 45 K (x=48). For T>Tm, a quadratic form can be effectively employed, with a negative T2 coefficient and a positive linear coefficient. The rise in resistivity for Talloys display only weakly field-dependent (to 10 kG) magnetoresistance.

  3. Structural relaxation in an amorphous rapidly quenched cobalt-based alloy

    International Nuclear Information System (INIS)

    Fradin, V.; Grynszpan, R.I.; Alves, F.; Houzali, A.; Perron, J.C.

    1995-01-01

    An amorphous melt-spun Co-based alloy (Metglas 2705 MN) is investigated by Doppler Broadening and Positron Lifetime techniques in order to follow the microstructural changes yielded by isochronal annealings before crystallization. The results are correlated with those of Differential Scanning Calorimetry and Coercive Field measurements. The quenched empty spaces underlined by Lifetime measurements are less than one atomic volume in size and migrate without clustering in larger voids. Both Positron Annihilation and Coercive Field investigations suggest that the overall decrease of free volume related to structural relaxation in this amorphous material, proceeds mainly via compositional short-range ordering. These local chemical rearrangements which lead to a partial disorientation of the magnetic moments act as strong pinning points for Bloch Walls. (orig.)

  4. Magnetic cluster mean-field description of spin glasses in amorphous La-Gd-Au alloys

    International Nuclear Information System (INIS)

    Poon, S.J.; Durand, J.

    1978-03-01

    Bulk magnetic properties of splat-cooled amorphous alloys of composition La/sub 80-x/Gd/sub x/Au 20 (0 less than or equal to x less than or equal to 80) were studied. Zero-field susceptibility, high-field magnetization (up to 75 kOe) and saturated remanence were measured between 1.8 and 290 0 K. Data were analyzed using a cluster mean-field approximation for the spin-glass and mictomagnetic alloys (x less than or equal to 56). Mean-field theories can account for the experimental freezing-temperatures of dilute spin-glasses in which the Ruderman-Kittel-Kasuya-Yosida interaction is dominant. For the dilute alloys, the role of amorphousness on the magnetic interactions is discussed. By extending the mean-field approximation, the concentrated spin-glasses are represented by rigid ferromagnetic clusters as individual spin-entities interacting via random forces. Scaling laws for the magnetization M and saturation remanent magnetization M/sub rs/ are obtained and presented graphically for the x less than or equal to 32 alloys in which M/x = g(H/x*, T/x), M/sub rs/(T)/x = M/sub rs/(0)/x/ exp (-α*T/x/sup p/) where x* is the concentration of clusters, α* is a constant, and p is the freezing-temperature exponent given by T/sub M/ infinity x/sup p/. It is found that p = 1 and 1.3 for the regions 4 less than or equal to x less than or equal to 40 respectively. An attempt is also made to account for the freezing temperatures of concentrated spin glasses. The strength of the interaction among clusters is determined from high-field magnetization measurements using the Larkin-Smith method modified for clusters. It is shown that for the x < 24 alloys, the size of the clusters can be correlated to the structural short-range order in the amorphous state. More concentrated alloys are marked by the emergence of cluster percolation

  5. Wetting behavior of molten In-Sn alloy on bulk amorphous and crystalline Cu40Zr44Al8Ag8

    International Nuclear Information System (INIS)

    Ma, G. F.; Zhang, H. F.; Li, H.; Hu, Z. Q.

    2007-01-01

    Using the sessile-drop method, the wettability of the molten In-Sn alloy on bulk amorphous and crystalline Cu 40 Zr 44 Al 8 Ag 8 alloy was studied at different temperatures. It was found that the equilibrium contact angle of In-Sn alloy melt on bulk amorphous substrate was smaller than that of the crystalline one. An intermetallic compound existed at the interface of In-Sn alloy on amorphous Cu 40 Zr 44 Al 8 Ag 8 , while no intermediate reaction layer was formed at the interface of In-Sn alloy on crystalline Cu 40 Zr 44 Al 8 Ag 8 in the temperature range studied

  6. Processing and characterization of amorphous magnesium based alloy for application in biomedical implants

    Directory of Open Access Journals (Sweden)

    Telma Blanco Matias

    2014-07-01

    Full Text Available Magnesium-based bulk metallic glasses are attractive due to their single-phase, chemically homogeneous alloy system and the absence of second-phase, which could impair the mechanical properties and corrosion resistance. However, one of the unsolved problems for the manufacturability and the applications of bulk metallic glasses is that their glass-forming ability is very sensitive to the preparation techniques and impurity of components since oxygen in the environment would markedly deteriorate the glass-forming ability. Therefore, the aim of this study was to establish proper processing conditions to obtain a magnesium-based amorphous ternary alloy and its characterization. The final composition was prepared using two binary master alloys by melting in an induction furnace. Carbon steel crucible was used in argon atmosphere with and without addition of SF6 gas in order to minimize the oxygen contamination. The microstructure, amorphous nature, thermal properties and chemical analysis of samples were investigated by scanning electron microscopy (SEM, X-ray diffraction (XRD, differential scanning calorimetry (DSC and inductively coupled plasma emission spectrometry, respectively. The oxygen content of the as-cast samples was chemically analyzed by using carrier gas hot extraction (O/N Analyzer TC-436/LECO and was kept bellow 25 ppm (without SF6 and 10 ppm (with SF6. Bulk samples were produced by rapid cooling in a cooper mold until 1.5 mm thickness, with amorphous structures being observed up to 2.5 mm.

  7. Internal friction study of neutron-irradiation effects on an amorphous Cu40Ti60 alloy

    International Nuclear Information System (INIS)

    Dong, Y.; Wu, G.; Xiao, K.; Li, X.; He, Y.

    1988-01-01

    Effects of neutron irradiation on the structure of an amorphous Cu 40 Ti 60 alloy have been studied by internal friction measurements. After irradiation, the position of the first internal friction peak remains almost unchanged and the shoulder position shifts towards a higher temperature by about 5 K, which indicates that the Cu 40 Ti 60 glass becomes more stable. These results are finally discussed based on the concept of changes of chemical short-range ordering and geometrical short-range ordering due to radiation damage

  8. Magnetic and Moessbauer studies of amorphous Fe72-xYxHo8B20 alloys

    International Nuclear Information System (INIS)

    Krishnan, R.; Dumond, Y.; Ajan, A.; Shringi, S.N.; Prasad, S.

    1996-01-01

    We have carried out magnetic and Moessbauer studies of amorphous Fe 72-x Y x Ho 8 B 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 J Fe-Fe , J Fe-Ho , etc. The Moessbauer studies show that the average hyperfine field decreases linearly with the addition of Y, in accordance with the decrease in the Fe moment. (orig.)

  9. Influence of Nd content on magnetic properties of amorphous FeB alloys

    Science.gov (United States)

    Hassanain, N.; Lassri, H.; Krishnan, R.; Berrada, A.

    The influence of the addition of Nd on the magnetic properties ( TC, M0, Hc, …) of FeB amorphous alloys is investigated. Using Chudnovsky's model we have analyzed our data and obtained some fundamental parameters. For instance, with the addition of Nd atoms the local anisotropy is 2.0 × 10 7 erg cm -3 and the exchange constant. A decreases from 38 × 10 -8 to 21.7 × 10 -8 erg cm -1 as the Nd concentration increases from 0 to 15%. The ferromagnetic exchange correlation length also decreases drastically from 353 to 80 Å in the same concentration range.

  10. Use of Δ E effect in amorphous alloys for magnetic-field measurement

    Science.gov (United States)

    Churenkov, A. V.; Listvin, V. N.; Kozel, S. M.

    1993-11-01

    Use of the ΔE effect in magnetically soft amorphous alloys (MSAA) for magnetic-field measurement is examined theoretically and experimentally. An MSAA microresonator in the form of bracket attached on one end is proposed as a sensing element. The microresonator is excited photothermally by intensity-modulated laser radiation, and the oscillations are registered by a fiber-optic interferometer. The use of fiber guides makes the sensor entirely passive, and frequency encoding minimizes the effect on the output signal of random attenuations in the fiber.

  11. Miscibility of amorphous ZrO2-Al2O3 binary alloy

    Science.gov (United States)

    Zhao, C.; Richard, O.; Bender, H.; Caymax, M.; De Gendt, S.; Heyns, M.; Young, E.; Roebben, G.; Van Der Biest, O.; Haukka, S.

    2002-04-01

    Miscibility is a key factor for maintaining the homogeneity of the amorphous structure in a ZrO2-Al2O3 binary alloy high-k dielectric layer. In the present work, a ZrO2/Al2O3 laminate thin layer has been prepared by atomic layer chemical vapor deposition on a Si (100) wafer. This layer, with artificially induced inhomogeneity (lamination), enables one to study the change in homogeneity of the amorphous phase in the ZrO2/Al2O3 system during annealing. High temperature grazing incidence x-ray diffraction (HT-XRD) was used to investigate the change in intensity of the constructive interference peak of the x-ray beams which are reflected from the interfaces of ZrO2/Al2O3 laminae. The HT-XRD spectra show that the intensity of the peak decreases with an increase in the anneal temperature, and at 800 °C, the peak disappears. The same samples were annealed by a rapid thermal process (RTP) at temperatures between 700 and 1000 °C for 60 s. Room temperature XRD of the RTP annealed samples shows a similar decrease in peak intensity. Transmission electronic microscope images confirm that the laminate structure is destroyed by RTP anneals and, just below the crystallization onset temperature, a homogeneous amorphous ZrAlxOy phase forms. The results demonstrate that the two artificially separated phases, ZrO2 and Al2O3 laminae, tend to mix into a homogeneous amorphous phase before crystallization. This observation indicates that the thermal stability of ZrO2-Al2O3 amorphous phase is suitable for high-k applications.

  12. NATO Advanced Research Workshop on Properties and Applications of Nanocrystalline Alloys from Amorphous Precursors

    CERN Document Server

    Idzikowski, Bogdan; Miglierini, Marcel

    2005-01-01

    Metallic (magnetic and non-magnetic) nanocrystalline materials have been known for over ten years but only recent developments in the research into those complex alloys and their metastable amorphous precursors have created a need to summarize the most important accomplishments in the field. This book is a collection of articles on various aspects of metallic nanocrystalline materials, and an attempt to address this above need. The main focus of the papers is put on the new issues that emerge in the studies of nanocrystalline materials, and, in particular, on (i) new compositions of the alloys, (ii) properties of conventional nanocrystalline materials, (iii) modeling and simulations, (iv) preparation methods, (v) experimental techniques of measurements, and (vi) different modern applications. Interesting phenomena of the physics of nanocrystalline materials are a consequence of the effects induced by the nanocrystalline structure. They include interface physics, the influence of the grain boundaries, the aver...

  13. High-field magnetization behavior in random anisotropy amorphous Co-Er alloys

    Science.gov (United States)

    Lassri, H.; Driouch, L.; Krishnan, R.

    1994-05-01

    Amorphous Co1-xErx ribbons with x=55 and 65 were prepared by the melt-spinning technique. Magnetization measurements were carried out in the temperature range 4-100 K under high magnetic fields up to 20 T. Even at 20 T the saturation is not fully attained. Assuming that Co has no moment in the alloy with x=65 the Er moment is found to be 7.0μB which indicates a speromagnetic spin structure. The Co moment in the alloy with x=55 is then found to be 0.1μB, which is negligibly small. By analyzing the approach to saturation using Chudnovsky's theory we have extracted some fundamental parameters.

  14. Thermal stability and primary phase of Al-Ni(Cu)-La amorphous alloys

    International Nuclear Information System (INIS)

    Huang Zhenghua; Li Jinfu; Rao Qunli; Zhou Youhe

    2008-01-01

    Thermal stability and primary phase of Al 85+x Ni 9-x La 6 (x = 0-6) and Al 85 Ni 9-x Cu x La 6 (x = 0-9) amorphous alloys were investigated by X-ray diffraction and differential scanning calorimeter. It is revealed that replacing Ni in the Al 85 Ni 9 La 6 alloy by Cu decreases the thermal stability and makes the primary phase change from intermetallic compounds to single fcc-Al as the Cu content reaches and exceeds 4 at.%. When the Ni and La contents are fixed, replacing Al by Cu increases the thermal stability but also promotes the precipitation of single fcc-Al as the primary phase

  15. Electronic Structures Localized at the Boron Atom in Amorphous Fe-B and Fe-B-P Alloys

    Science.gov (United States)

    Yasuda, Hidehiro; Nakayama, Hiroshi; Fujita, Hiroshi

    1989-11-01

    The electronic structures localized at the B in amorphous Fe-B and Fe-B-P alloys and their crystallized alloys were studied by Auger valence electron spectroscopy and the states of solute B are discussed based on the change in the degree of covalent bonding and the charge transfer between the Fe and B atoms. In amorphous phases, the charge transfers from Fe to B above 15at%B where B atoms occupy the substitutionallike situations, and from B to Fe below 15at%B where B atoms occupy the interstitiallike situations. Magnetic properties depend on such states of solute B. In crystalline phases, covalent bonding becomes dominant because the electron excitation occurs to the B2p state. Consequently, amorphous phases are more metallic in character than crystalline phases and amorphous structures are stabilized by a mixture of more than two different bonding states.

  16. Performance of single wire earth return transformers with amorphous alloy core in a rural electric energy distribution system

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano

    2012-10-01

    Full Text Available In this paper are presented some considerations about the performance of single wire earth return amorphous alloy core transformers in comparison with conventional silicon steel sheets cores transformers used in rural electric energy distribution network. It has been recognized that amorphous metal core transformers improve electrical power distribution efficiency by reducing transformer core losses. This reduction is due to some electromagnetic properties of the amorphous alloys such as: high magnetic permeability, high resistivity, and low coercivity. Experimental results obtained with some single-phase, 60 Hz, 5 kVA amorphous core transformers installed in a rural area electric distribution system in Northern Brazil have been confirming their superior performance in comparison to identical nominal rated transformers built with conventional silicon steel cores, particularly with regard to the excitation power and to the no-load losses.

  17. Co dependence of Curie temperature in amorphous Fe-Co-Zr-B-Nb alloys with high glass-forming ability

    International Nuclear Information System (INIS)

    Yao, B; Zhang, Y; Si, L; Tan, H; Li, Y

    2004-01-01

    Effects of Co substitution for Fe on the Curie temperature (T c ), glass-forming ability (GFA) and thermal stability of amorphous Fe 61-x Co x Zr 5 B 30 Nb 4 (FCZBN) alloys were studied for Co content ranging from 0 to 15 at. %. The T c shows a sinusoid-like behaviour with increasing Co content, revealing two maxima at 3 and 12.5 at. % Co and a minimum at 7.5 at. % Co. Co content dependences of glass transition (T g ), crystallization (T x ) and reduced glass transition temperatures (T rg ) of the amorphous alloys are almost completely opposite to that of the T c . The T c decreases with increasing T g and T rg , but increases with increasing Co content. The Co content dependence of the T c is suggested to relate to both Co content and high GFA of the amorphous alloys

  18. Low-temperature specific heat of the 'nearly ferromagnetic' amorphous alloy Ysub(0.22)Nisub(0.78)

    International Nuclear Information System (INIS)

    Garoche, P.; Veyssie, J.J.; Lienard, A.; Rebouillat, J.P.

    1979-01-01

    Results of specific heat measurements, between 0.3K and 10 K in magnetic fields up to 75 kOe, on the 'nearly ferromagnetic' amorphous alloy Ysub(0.22)Nisub(0.78) are reported. The results, especially the magnetic field dependence, exclude any appreciable contribution from uniform paramagnons. In contrast a quantitative analysis is obtained in terms of superparamagnetic clusters, demonstrating that the onset of ferromagnetism, as a function of concentration, is inhomogeneous in this amorphous metallic system. (author)

  19. Reactive wetting of amorphous silica by molten Al–Mg alloys and their interfacial structures

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Laixin [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Zhang, Dan [Editorial Office, Journal of Bionic Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Jiang, Qichuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China)

    2016-07-30

    Highlights: • The wettability improves with increasing Mg concentration and temperature. • Reaction product zone consists of layered structures relating with Mg concentration. • Formation of MgAl{sub 2}O{sub 4} and MgO at the interface does not promote the wettability. • Formation of Mg{sub 2}Si plays a dominant role in promoting the wettability. • Anomalous recession of the triple line was mainly due to diminishing Mg in the alloy. - Abstract: The reactive wetting of amorphous silica substrates by molten Al–Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO{sub 2} surface was 115° while that for pure Mg was 35° at 1073 K. For the Al–Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al–Mg alloy on the SiO{sub 2} surface was mainly attributed to the formation of Mg{sub 2}Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  20. Quantitative description of the magnetization curves of amorphous alloys of the series a-DyxGd1-xNi

    International Nuclear Information System (INIS)

    Barbara, B.; Filippi, J.; Amaral, V.S.

    1992-01-01

    The magnetization curves of the series of amorphous alloys Dy x Gd 1-x Ni measured between 1.5 and 4.2 K and up to 15 T, have been fitted to the zero kelvin analytical model of Chudnovsky. The results of these fits allow a detailed understanding of the magnetization curves of amorphous alloys with ferromagnetic interactions. In particular, the ratio D/J of the local anisotropy and exchange energies, and the magnetic and atomic correlation lengths, are accurately determined. (orig.)

  1. Crystallization of Fe83B17 amorphous alloy by electric pulses produced by a capacitor discharge

    International Nuclear Information System (INIS)

    Georgarakis, Konstantinos; Dudina, Dina V.; Mali, Vyacheslav I.; Anisimov, Alexander G.; Bulina, Natalia V.; Moreira Jorge, Alberto Jr.; Yavari, Alain R.

    2015-01-01

    Heating of conductive materials by electric current is used in many technological processes. Application of electric pulses to metallic glasses induces their fast crystallization, which is an interesting and complex phenomenon. In this work, crystallization of the Fe 83 B 17 amorphous alloy induced by pulses of electric current produced has been studied using X-ray diffraction and transmission electron microscopy. Ribbons of the alloy were directly subjected to single pulses of electric current 250 μs long formed by a capacitor discharge. As the value of ∫I 2 dt was increased from 0.33 to 2.00 A 2 s, different crystallization stages could be observed. The crystallization began through the formation of the nuclei of α-Fe. At high values of ∫I 2 dt, α-Fe and tetragonal and orthorhombic Fe 3 B and Fe 23 B 6 were detected in the crystallized ribbons with crystallites of about 50 nm. Thermal annealing of the ribbons at 600 C for 2 min resulted in the formation of α-Fe and tetragonal Fe 3 B. It was concluded that pulses of electric current produced by a capacitor discharge induced transformation of the Fe 83 B 17 amorphous phase into metastable crystalline products. (orig.)

  2. Theoretical study of the localization-delocalization transition in amorphous molybdenum-germanium alloys

    International Nuclear Information System (INIS)

    Ding, K.; Andersen, H.C.

    1987-01-01

    Electronic structure calculations were performed for amorphous germanium and amorphous alloys of molybdenum and germanium. The calculations used Harrison's universal linear-combination-of-atomic-orbitals parameters to generate one-electron Hamiltonians for structural configurations obtained from molecular-dynamics simulations. The density of states calculated for a model of a-Ge showed a distinct pseudogap, although with an appreciable density of states at the minimum. The states in the pseudogap are localized. As the concentration of Mo atoms increases, the pseudogap of the density of states is gradually filled up. The density of states at the Fermi energy calculated for our model of the alloys agrees quite well with that experimentally determined by Yoshizumi, Geballe, and co-workers. The localization index for the states at the Fermi energy is a decreasing function of Mo concentration in the range of 2--14 at. % Mo and the localization length is an increasing function of molybdenum concentration. These results are consistent with the experimental observation of an insulator-metal transition at about 10 at. % Mo

  3. 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

  4. Nanocrystals and amorphous matrix phase studies of Finemet-like alloys containing Ge

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J.A., E-mail: jmoya.fi.uba@gmail.co [IESIING, Facultad de Ingenieria e Informatica, UCASAL, A4402FYP Salta (Argentina); Lab. Solidos Amorfos, Facultad de Ingenieria, INTECIN, UBA-CONICET (Argentina); CONICET (Argentina)

    2010-07-15

    Two simple models were developed in order to determine the chemical composition of both nanocrystals and intergranular amorphous phases in nanocrystallized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} containing Ge using data from X-ray diffraction and Moessbauer spectroscopy techniques. Saturation magnetization of the amorphous intergranular matrix (M{sub s}{sup am}) was calculated considering the contribution of the alpha-Fe(Si,Ge) nanocrystals and saturation magnetization of the alloys. The behavior of M{sub s}{sup am} with the iron content of the matrix was obtained and discussed. The exchange stiffness constant for the nanograins and for the amorphous phases was determined. The increment in the coercive field (H{sub c}) with increasing Ge content was evaluated using two theoretical models for the random magnetocrystalline anisotropy constant (). Results show that the magnetic hardening observed could not be attributed to an increase in but mainly to an important increment of the magnetostriction constant of the alpha-Fe(Si,Ge) nanocrystals (lambda{sub s}{sup cr}). Values for lambda{sub s}{sup cr} are proposed.

  5. Research on Zr50Al15-xNi10Cu25Yx amorphous alloys prepared by mechanical alloying with commercial pure element powders

    International Nuclear Information System (INIS)

    Long Woyun; Ouyang Xueqiong; Luo Zhiwei; Li Jing; Lu Anxian

    2011-01-01

    Amorphous Zr 50 Al 15-x Ni 10 Cu 25 Y x alloy powders were fabricated by mechanical alloying at low vacuum with commercial pure element powders. The effects on glass forming ability of Al partial substituted by Y in Zr 50 Al 15 Ni 10 Cu 25 and thermal stability of Si 3 N 4 powders addition were investigated. The as-milled powders were characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimeter. The results show that partial substitution of Al can improve the glass forming ability of Zr 50 Al 15 Ni 10 Cu 25 alloy. Minor Si 3 N 4 additions raise the crystallization activation energy of the amorphous phase and thus improve its thermal stability. -- Research Highlights: → ZrAlNiCu amorphous alloys can be synthesized by MA in low cost. → Appropriate amount of Al substituted by Y in ZrAlNiCu alloy can improve its glass forming ability. → A second phase particle addition helps to improve the thermal stability of the amorphous matrix.

  6. Fluxing purification and its effect on magnetic properties of high-B{sub s} FeBPSiC amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Jing [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang, Liaoning 110870 (China); Wang, Anding, E-mail: anding@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Yue, Shiqiang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Kong, Fengyu [School of Materials and Chemical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Qiu, Keqiang, E-mail: kqqiu@163.com [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang, Liaoning 110870 (China); Chang, Chuntao; Wang, Xinmin [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Liu, Chain-Tsuan, E-mail: chainliu@cityu.edu.hk [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2017-07-01

    Highlights: • Surface crystallization in Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbon was inhibited by flux purification. • Amorphous Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbon was made with industrial process and materials. • The ribbons exhibit high B{sub s} of 1.65 T, low H{sub c} of 2 A/m, and high μ{sub e} of 9.7 × 10{sup 3}. • High melting point inclusions trigger the surface crystallization as nuclei. - Abstract: A high-B{sub s} amorphous alloy with the base composition Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} was used to study the effects of fluxing purification on amorphous forming ability and magnetic properties of the alloy prepared with raw materials in industrialization. By using fluxing purification, the surface crystallization was suppressed and fully amorphous Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbons with a maximum thickness of 48 μm were successfully achieved by using an industrial process and materials. The amorphous ribbons made with industrial-purified alloys exhibit excellent magnetic properties, containing high-B{sub s} of 1.65 T, low H{sub c} of 2.0 A/m, and high μ{sub e} of 9.7 × 10{sup 3} at 1 kHz. Impurities in the melting alloys exist in three forms and have different effluences on magnetic properties. The surface crystallization was triggered by the impurities which exist as high melting point inclusions serving as nuclei. Thus, fluxing purification is a feasible way for industrialization of high-B{sub s} FeBPSiC amorphous alloys.

  7. Gallium-enhanced phase contrast in atom probe tomography of nanocrystalline and amorphous Al-Mn alloys.

    Science.gov (United States)

    Ruan, Shiyun; Torres, Karen L; Thompson, Gregory B; Schuh, Christopher A

    2011-07-01

    Over a narrow range of composition, electrodeposited Al-Mn alloys transition from a nanocrystalline structure to an amorphous one, passing through an intermediate dual-phase nanocrystal/amorphous structure. Although the structural change is significant, the chemical difference between the phases is subtle. In this study, the solute distribution in these alloys is revealed by developing a method to enhance phase contrast in atom probe tomography (APT). Standard APT data analysis techniques show that Mn distributes uniformly in single phase (nanocrystalline or amorphous) specimens, and despite some slight deviations from randomness, standard methods reveal no convincing evidence of Mn segregation in dual-phase samples either. However, implanted Ga ions deposited during sample preparation by focused ion-beam milling are found to act as chemical markers that preferentially occupy the amorphous phase. This additional information permits more robust identification of the phases and measurement of their compositions. As a result, a weak partitioning tendency of Mn into the amorphous phase (about 2 at%) is discerned in these alloys. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness

    International Nuclear Information System (INIS)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J.

    2007-01-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  9. Growth of amorphous and epitaxial ZnSiP2–Si alloys on Si

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Aaron D. [National Renewable Energy Laboratory; Golden; USA; Department of Physics; Colorado School of Mines; Miller, Elisa M. [National Renewable Energy Laboratory; Golden; USA; Norman, Andrew G. [National Renewable Energy Laboratory; Golden; USA; Schnepf, Rekha R. [National Renewable Energy Laboratory; Golden; USA; Department of Physics; Colorado School of Mines; Leick, Noemi [National Renewable Energy Laboratory; Golden; USA; Perkins, Craig [National Renewable Energy Laboratory; Golden; USA; Stradins, Paul [National Renewable Energy Laboratory; Golden; USA; Department of Physics; Colorado School of Mines; Toberer, Eric S. [National Renewable Energy Laboratory; Golden; USA; Department of Physics; Colorado School of Mines; Tamboli, Adele C. [National Renewable Energy Laboratory; Golden; USA; Department of Physics; Colorado School of Mines

    2018-01-01

    ZnSiP2is a wide band gap material lattice matched with Si, with potential for Si-based optoelectronics. Here, amorphous ZnSiP2–Si alloys are grown with tunable composition. Films with Si-rich compositions can be crystallized into epitaxial films.

  10. Nanocrystal Growth in Thermally Treated Fe75Ni2Si8B13C2 Amorphous Alloy

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica M.; Blagojević, V.; Minić, Dušan M.; David, Bohumil; Pizúrová, Naděžda; Žák, Tomáš

    43A, č. 9 (2012), s. 3062-3069 ISSN 1073-5623 R&D Projects: GA MŠk 1M0512 Institutional support: RVO:68081723 Keywords : Nanocrystal growth * Fe75Ni2Si8B13C2 * Amorphous alloy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.627, year: 2012

  11. Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

    Energy Technology Data Exchange (ETDEWEB)

    Galván-Colín, Jonathan, E-mail: jgcolin@ciencias.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Ariel A., E-mail: valladar@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Renela M.; Valladares, Alexander [Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-542, México, D.F. 04510, México (Mexico)

    2015-10-15

    Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of Cu{sub x}Zr{sub 100−x} (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature.

  12. Short-range order in ab initio computer generated amorphous and liquid Cu-Zr alloys: A new approach

    Science.gov (United States)

    Galván-Colín, Jonathan; Valladares, Ariel A.; Valladares, Renela M.; Valladares, Alexander

    2015-10-01

    Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of CuxZr100-x (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature.

  13. Vibrational, optical and structural studies of an amorphous Se(0.90)S(0.10) alloy produced by mechanical alloying.

    Science.gov (United States)

    Machado, K D; Sanchez, D F; Maciel, G A; Brunatto, S F; Mangrich, A S; Stolf, S F

    2009-05-13

    The local atomic order of an amorphous Se(0.90)S(0.10) alloy produced by mechanical alloying was studied by x-ray diffraction and extended x-ray absorption fine structure (EXAFS) data obtained at three temperatures, T = 300, 200 and 30 K. From the cumulant analysis of the EXAFS data, structural properties such as average interatomic distances, average coordination numbers, Debye-Waller factors and anharmonicity, given by the third cumulant, were obtained. The results found indicate that there is alloying at an atomic level, and Se-S pairs are more disordered and distorted than Se-Se ones due to the milling process.

  14. Crystalline to amorphous transition in solids upon high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Sundeev, R.V., E-mail: apricisvir@gmail.com [I.P. Bardin Central Research Institute for Ferrous Metallurgy, 2-ya Baumanskaya 9/23, Moscow 105005 (Russian Federation); Moscow State University of Instrument Engineering and Computer Science, Stromynka 20, Moscow 107996 (Russian Federation); Glezer, A.M. [I.P. Bardin Central Research Institute for Ferrous Metallurgy, 2-ya Baumanskaya 9/23, Moscow 105005 (Russian Federation); Moscow State University of Instrument Engineering and Computer Science, Stromynka 20, Moscow 107996 (Russian Federation); National University of Science and Technology “MISIS”, Leninsky avenue 4, Moscow 119049 (Russian Federation); Shalimova, A.V. [I.P. Bardin Central Research Institute for Ferrous Metallurgy, 2-ya Baumanskaya 9/23, Moscow 105005 (Russian Federation)

    2014-10-25

    Highlights: • Ti–Ni, Zr and Fe-based alloys were deformed using HTP processing. • Ability to deformation-induced amorphization (DIA) of these alloys was studied. • Amorphization is determined by mechanical, thermodynamic and concentration factors. • The smaller stability of phases the higher their ability to deformation amorphization. • There is the difference between of DIA and to thermal amorphization in the nature. - Abstract: The amorphization behavior of the crystalline multicomponent Ni{sub 50}Ti{sub 30}Hf{sub 20}, Ti{sub 50}Ni{sub 25}Cu{sub 25,} Zr{sub 50}Ni{sub 18}Ti{sub 17}Cu{sub 15}, and Fe{sub 78}B{sub 8.5}Si{sub 9}P{sub 4.5} alloys upon severe plastic deformation (SPD) has been studied. It is shown that the crystalline to amorphous transition is determined by the ability of the crystals to accumulation of deformation defects under mechanical action, by the thermodynamic stability of the crystalline phases contained in the alloy, and by the possibility of the diffusion processes necessary for the change in the chemical composition of the crystalline and amorphous phases upon deformation. It is found that the susceptibility to amorphization upon SPD does not coincide with the tendency of the alloys to amorphization upon melt quenching.

  15. Study on the solid solubility extension of Mo in Cu by mechanical alloying Cu with amorphous Cr(Mo)

    International Nuclear Information System (INIS)

    Xi Shengqi; Zuo Kesheng; Li Xiaogang; Ran Guang; Zhou Jingen

    2008-01-01

    This paper presents the extension of the solid solubility of Mo in Cu by a mechanical alloying technique. Two binary systems, Cu-10 wt.% Mo and Cr-50 wt.% Mo, and one ternary system, Cu-20 wt.% Cr(Mo), are investigated. The solid solubility of Mo in Cu has been shown to be less than 4.3 at.% when the Cu-Mo system is mechanically alloyed, whereas when the Cr-Mo system is mechanically alloyed all of Mo dissolves into Cr, forming an amorphous Cr(Mo). Similarly, all of 10 wt.% Mo dissolve into Cu when Cu-20 wt.% amorphous Cr(Mo) is mechanically alloyed. Based on Miedema's model, the Gibbs free-energy changes in these three alloy systems during the formation of solid solutions are calculated to be positive, which means that thermodynamic barriers exist for the formation of these three alloy systems in solid solution states. The mechanism of solid solubility extension in these mechanical alloyed systems is discussed. The conclusion is that the extension of solid solubility is favoured by adding a third element, such as Cr, to the Cu-Mo system

  16. Local order dynamics: its application to the study of atomic mobility, of point defects in crystalline alloys, and of structural relaxation in amorphous alloys

    International Nuclear Information System (INIS)

    Balanzat, Emmanuel

    1983-01-01

    This research thesis addressed the study of the atomic mobility mechanism and of the atom movement dynamics in the case of crystalline alloys and of amorphous alloys. The first part is based on a previous study performed on an α-Cu 70 -Zn 30 crystalline alloy, and addresses the case of an α-Au 70 -Ni 30 alloy. The specificity of this case relies in the fact that the considered solid solution is metastable and susceptible to de-mixing in the considered temperature range. This case of off-equilibrium crystalline alloy is at the crossroad between steady crystalline alloys and metallic glasses which are studied in the second part. The third part addresses the irradiation of metallic amorphous alloys by fast particles (neutrons or electrons). The author tried to characterise atomic defects induced by irradiation and to compare them with pre-existing ones. He studied how these defects may change atomic mobility, and, more generally, to which extent the impact of energetic particles could modify local order status

  17. Invar, AF-Invar, Anti-Invar and Martensite in FCC Fe-Based Alloys : An Attempt to Order this Chaos

    OpenAIRE

    Wassermann, E.; Entel, P.

    1995-01-01

    Systematics concerning magnetic and structural phase transitions within Fe-based sytems can be achieved if experimental data are analyzed as a function of composition and the atomic volume. The findings can be understood from calculations of the exchange coupling of pure fcc Fe as a function of the n.n. distance. Decisive is that the volume increase going along with Invar, AF-Invar, Anti-Invar as well as martensite transitions originates from a charge transfer between antibonding electronic o...

  18. Amorphization threshold in Si-implanted strained SiGe alloy layers

    International Nuclear Information System (INIS)

    Simpson, T.W.; Love, D.; Endisch, E.; Goldberg, R.D.; Mitchell, I.V.; Haynes, T.E.; Baribeau, J.M.

    1994-12-01

    The authors have examined the damage produced by Si-ion implantation into strained Si 1-x Ge x epilayers. Damage accumulation in the implanted layers was monitored in situ by time-resolved reflectivity and measured by ion channeling techniques to determine the amorphization threshold in strained Si 1-x Ge x (x = 0.16 and 0.29) over the temperature range 30--110 C. The results are compared with previously reported measurements on unstrained Si 1-x Ge x , and with the simple model used to describe those results. They report here data which lend support to this model and which indicate that pre-existing strain does not enhance damage accumulation in the alloy layer

  19. Magnetoelectric effect in layered structures of amorphous ferromagnetic alloy and gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Bichurin, M.I., E-mail: mirza.bichurin@novsu.ru; Petrov, V.M.; Leontiev, V.S.; Ivanov, S.N.; Sokolov, O.V.

    2017-02-15

    A paper devotes to theoretical and experimental studying the magnetoelectric interaction in layered structures of amorphous ferromagnetic alloy and single- crystal gallium arsenide. The authors investigated the magnetoelectric effect in the (100) plane of gallium arsenide in the electromechanical resonance range of 200–240 kHz and obtained maximal ME voltage coefficient of 120 V/A at bias field equaled 3.6 kA/m for the direction parallel to the [011] axis. Also the magnetoelectric effect in the (110) and (111) planes is discussed. The results can be used for design of new electronic devices based on the magnetostrictive-semiconductor materials. - Highlights: • Theoretical modeling of ME interaction was conducted. • Experimental dependencies in the resonance range were done. • Maximal ME effect of gallium arsenide was observed.

  20. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Yunus Eren [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

  1. Coercivity of domain wall motion in thin films of amorphous rare earth-transition metal alloys

    Science.gov (United States)

    Mansuripur, M.; Giles, R. C.; Patterson, G.

    1991-01-01

    Computer simulations of a two dimensional lattice of magnetic dipoles are performed on the Connection Machine. The lattice is a discrete model for thin films of amorphous rare-earth transition metal alloys, which have application as the storage media in erasable optical data storage systems. In these simulations, the dipoles follow the dynamic Landau-Lifshitz-Gilbert equation under the influence of an effective field arising from local anisotropy, near-neighbor exchange, classical dipole-dipole interactions, and an externally applied field. Various sources of coercivity, such as defects and/or inhomogeneities in the lattice, are introduced and the subsequent motion of domain walls in response to external fields is investigated.

  2. Devitrification of Co-Based Amorphous Alloys, Enhanced Initial Permeability and Giant Magneto-Impedance

    Science.gov (United States)

    Hoque, S. Manjura; Hakim, M. A.; Khan, F. A.; Saha, D. K.

    2008-04-01

    Devitrification of Co-based amorphous alloys, enhanced initial permeability and giant magneto-impedance have been studied for the samples of composition, Co68Fe4Ni1Si15B12, Co67Fe4Ni2Si15B12 and Co67Fe4Mo2Si15B12. Ultra-soft magnetic properties has been observed by appropriate annealing manifested by high initial permeability of the order of 104 and low relative loss factor of 10-6. Giant magneto-impedance ratio (GMIR) has been obtained for these compositions measured with a current driving frequency of 4.5 MHz. Field dependence of GMIR response varies for different composition and annealing condition.

  3. Structure Optimization and Performance Analysis of SRM with Amorphous Alloys Core using FEM

    Directory of Open Access Journals (Sweden)

    Yiduan CHEN

    2014-01-01

    Full Text Available This paper presents the performance computation of three-phase 6/4 poles Switched Reluctance Motor (SRM with amorphous alloy core using transient Finite Element Analysis (FEA in which the magnetic field is combined with a driving circuit. In order to minimize torque ripple in SRM, this paper proposes not only optimal combination of stator pole arc and rotor pole arc but also the turn-on and turn-off angles using parameterized transient FEA and response surface methodology (RSM. The magnetic fields distribution, the winding flux linkage, the phase inductance curve, the iron losses and the torque characteristics of the prototype SRM at low-speed are investigated. All studies show that the prototype SRM is potential to apply in home appliance applications.

  4. Effect of Si and Co on the crystallization of Al-Ni-RE amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.H. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China); Bian, X.F. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China)], E-mail: xfbian@sdu.edu.cn

    2008-04-03

    Crystallization of Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 7}Nd{sub 6} and Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} amorphous alloys has been studied by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The multiple transition metal (TM) (containing metalloid element) have significant effect on the crystallization behavior. A small addition of Si transforms a eutectic crystallization (Al{sub 85}Ni{sub 10}Ce{sub 5}) to a primary crystallization (Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}); while a small addition of Co transforms a primary crystallization (Al{sub 87}Ni{sub 7}Nd{sub 6}) to a eutectic crystallization (Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6}). In addition, the activation energies for crystallization (E{sub a}) are obtained to be 191, 290, 221 and 166 kJ/mol for the Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} and Al{sub 87}Ni{sub 7}Nd{sub 6} amorphous alloys based on the Kissinger method, respectively. It is found that the primary crystallization of fcc-Al is characteristic of a lower E{sub a}, as compared with eutectic crystallization.

  5. Highly ordered amorphous silicon-carbon alloys obtained by RF PECVD

    CERN Document Server

    Pereyra, I; Carreno, M N P; Prado, R J; Fantini, M C A

    2000-01-01

    We have shown that close to stoichiometry RF PECVD amorphous silicon carbon alloys deposited under silane starving plasma conditions exhibit a tendency towards c-Si C chemical order. Motivated by this trend, we further explore the effect of increasing RF power and H sub 2 dilution of the gaseous mixtures, aiming to obtain the amorphous counterpart of c-Si C by the RF-PECVD technique. Doping experiments were also performed on ordered material using phosphorus and nitrogen as donor impurities and boron and aluminum as acceptor ones. For nitrogen a doping efficiency close to device quality a-Si:H was obtained, the lower activation energy being 0,12 eV with room temperature dark conductivity of 2.10 sup - sup 3 (OMEGA.cm). Nitrogen doping efficiency was higher than phosphorous for all studied samples. For p-type doping, results indicate that, even though the attained conductivity values are not device levels, aluminum doping conducted to a promising shift in the Fermi level. Also, aluminum resulted a more efficie...

  6. Concentration dependence of the magnetic properties in amorphous Fe-P-B alloys

    International Nuclear Information System (INIS)

    Durand, J.

    1976-05-01

    The variation with composition of the magnetic properties of amorphous Fe--P--B alloys obtained by splat-cooling is discussed. For a given Fe concentration, the magnetic moment per atom anti μ and the Curie temperature T/sub c/ both increase with the substitution of B for P. The variation of anti μ and T/sub c/ as a function of the B content had the same discontinuity as that occurring between the two phases epsilon and psilon 1 of the crystalline Fe 3 P/sub 1-x/B/sub x/ compounds. The variation of anti μ and T/sub c/ was also studied when one metalloid (P or B) substitutes for Fe, the other metalloid remaining constant. The value of anti μ was found to decrease when the P or B content is increased, as expected from a rigid band model. In the same concentration range, T/sub c/ increases with either P or B. The different behaviors of anti μ and T/sub c/ are tentatively explained by assuming that the amorphous Fe has two magnetic states (ferro and antiferromagnetic) as already suggested for crystalline Fe in a fcc environment

  7. Formation of amorphous alloys by mechanical alloying for platinum group metal-M(M=Zr or Al) system; Mechanical alloying ni yoru kikinzoku (Pd,Pt) to M(Zr aruiwa Al) tono kongo funmatsu no hishoshitsuka

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzuki, T.; Arakawa, T. [Kinki Univ., Higashi-Osaka, Osaka (Japan)

    1998-08-15

    The intermetallic compounds containing precious metals such as platinum white gold are widely used in chemistry or industry as catalysts. These alloy catalysts are mainly used in grinding the materials prepared by solidifying liquids. The authors of the paper attempt to prepare alloy powders of precious metal with Zr or Al by mechanical alloying (MA). As an object of applying them on a catalyst, alloy powders of precious metals (Pd and Pt) and M (Zr or Al) are regulated by the mechanical alloying reaction, and the results show that the Pd and Pt show different MA reaction while using Al as the M, the former generates an intermetallic compound as PdAl during the halfway point of the MA reaction, but the later generates amorphous powders. But, each of them generates amorphous alloys only while using Zr and the M. As a result of differential thermal analysis and electrical resistivity measurement investigating the crystalline process of the obtained amorphous alloys, it is clarified that the Pt-Al base alloy shows higher crystalline temperature compared with the other alloys. 8 refs., 6 figs.

  8. 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.

  9. Effect of crystallization on corrosion behavior of Fe40Ni38B18Mo4 amorphous alloy in 3.5% sodium chloride solution

    DEFF Research Database (Denmark)

    Wu, Y.F.; Chiang, Wen-Chi; Wu, J.K.

    2008-01-01

    After the crystallization of F40Ni38B18Mo4 amorphous alloy by vacuum annealing, the corrosion resistance of its crystalline state shows inferior to its amorphous state due to the local cell action between Ni phase and (Fe, Ni, Mo)(23)B-6 phase in matrix.......After the crystallization of F40Ni38B18Mo4 amorphous alloy by vacuum annealing, the corrosion resistance of its crystalline state shows inferior to its amorphous state due to the local cell action between Ni phase and (Fe, Ni, Mo)(23)B-6 phase in matrix....

  10. The effect of minor addition of insoluble elements on transformation kinetics in amorphous Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.; Perepezko, J.H., E-mail: perepezk@engr.wisc.edu

    2015-09-15

    Highlights: • By doping Pb or In in AlYFe alloys, the primary crystallization of Al is promoted. • The catalytic effect is based on the good wetting behavior between Al and Pb. • Pb promotes crystallization by providing heterogeneous nucleation sites. • Through doping 0.5–2 at.% of In, T{sub x} decreases by 35–47 °C. • The coherent interface shows a good contacting behavior between Al and In. - Abstract: Nanocrystalline metallic materials based on partial devitrification of amorphous aluminum alloys show an attractive combination of high strength and low density. A key feature concerning the improved mechanical properties is the high number density of Al nanocrystals (10{sup 22}–10{sup 23} m{sup −3}) that precipitate within the amorphous precursor structure upon low temperature annealing. For Al{sub 87}Y{sub 7}Fe{sub 5}Pb, the melt-spun ribbons consisted of an amorphous matrix with a dispersion of Pb nanoparticles (10 nm diameter). HRTEM images of the Pb–Al interface revealed a good wetting behavior between the Al and the Pb nanoparticles. Isothermal annealing for Al{sub 87}Y{sub 7}Fe{sub 5}Pb showed no transient stage even though the crystallization onset, T{sub x}, was at a much lower temperature (247 °C) compared with Al{sub 88}Y{sub 7}Fe{sub 5} (267 °C). For Al{sub (88−x)}Y{sub 7}Fe{sub 5}In{sub x} (x = 0.5, 1.0, 1.5, 2.0), the DSC results indicated that T{sub x} continuously decreased from 232 °C to 220 °C as the indium level increases from 0.5 at.% to 2.0 at.%. Under STEM, the image showed a coherent interface between Al and In particles. In the analysis of the transformation kinetics, the addition of minor elements can effectively promote additional nucleation of Al nanocrystals by providing heterogeneous nucleation sites. These developments offer new opportunities for the control of nanoscale microstructures.

  11. Magnetic properties of exchange-coupled trilayers of amorphous rare-earth-cobalt alloys

    International Nuclear Information System (INIS)

    Wuechner, S.; Toussaint, J.C.; Voiron, J.

    1997-01-01

    From amorphous thin films from alloys of rare earths (Gd, Sm), yttrium or zirconium with cobalt we have prepared trilayers with very clean interfaces appropriate for the study of magnetic coupling. The sandwiches were typically Y-Co/Gd-Co/Y-Co and Sm-Co/X/Sm-Co ' (X=Gd-Co, Co-Zr, Co). The three individual layers are coupled magnetically by exchange interactions between cobalt moments throughout the entire sample. This coupling associated with the specific properties of the given alloy (magnetic moment, anisotropy, coercivity) leads to ferrimagnetic or ferromagnetic structures of the magnetization of adjacent layers and to novel magnetization processes. For systems consisting of magnetically hard external layers with different coercivities and a soft central layer (Sm-Co/X/Sm-Co ' , X=Gd-Co, Co-Zr), the influence of the central layer close-quote s thickness and type of the material on coupling and magnetization processes have been studied quantitatively. Numerical simulations using a one-dimensional model for describing the magnetization processes observed in sandwich systems fit the magnetization curves of these model systems particularly well. copyright 1997 The American Physical Society

  12. Magnetic and thermal properties of amorphous TbFeCo alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke, E-mail: K.Wang@hqu.edu.cn; Dong, Shuo; Huang, Ya; Qiu, Yuzhen

    2017-07-15

    Highlights: • Significant increase in magnetization is observed in TbFeCo upon crystallization. • The crystallization temperature is determined in the range between 400 and 450 °C. • The activation barriers for structural changes are obtained successfully. • Better thermal stability against crystallization and oxidation is demonstrated in FeCo-rich sample than Tb-rich type. - Abstract: Amorphous TbFeCo material with perpendicular magnetic anisotropy is currently attracting more attention for potential applications in spintronic devices and logic memories. We systematically investigate magnetic, structural, thermal, optical and electrical properties of TbFeCo alloy films. It shows out-of-plane easy axis of the films turns into in-plane orientation after annealing. Significant increase in saturation magnetization in the temperature range between 400 and 450 °C is revealed by thermomagnetic measurements. The occurrence of crystallization and oxidation at high temperatures is confirmed by X-ray diffraction measurements. Pronounced changes in optical reflectance and sheet resistance are observed with temperature, in line with structural relaxation and change. The activation barriers for crystallization and oxidation are determined to be 1.01 eV and 0.83 eV, respectively, for FeCo-rich and Tb-rich samples. Better thermal stability against crystallization and oxidation is demonstrated in the FeCo-rich sample than the Tb-rich type. Our results provide some useful information for the alloy used in device fabrication.

  13. First-principle study of the structural, electronic, and magnetic properties of amorphous Fe-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tian Hua; Zhang Chong [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024 (China); Zhao Jijun, E-mail: zhaojj@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024 (China); Dong Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wen Bin [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Wang Qing [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2012-01-15

    The structural, electronic, and magnetic properties of amorphous Fe{sub 100-x}B{sub x} alloys (x=9, 17, 25, 27.3, 33.3, 36.3) are investigated using first-principles calculations. In these amorphous alloys, the short-range order is manifested as a series of Fe- or B-centered polyhedra such as tricapped trigonal prism, icosahedron, and bcc-like structural unit. The electron densities of states of the amorphous alloys resemble those of crystalline Fe borides, which further confirm the similarity of the local order in the amorphous and crystalline phases. All B atoms carry small negative moments of about -0.1{mu}{sub B}, while small negative moments are also found on very few Fe sites for the Fe-rich compositions (x=9, 17). The average magnetic moment per Fe atom decreases nonlinearly with increasing B composition, which can be associated with the nonlinear relationship between mass density and composition.

  14. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    Science.gov (United States)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E. M.

    1991-10-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$-- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y2).

  15. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    International Nuclear Information System (INIS)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E.M.

    1991-01-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$---- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y 2 )

  16. Atmospheric and milling-device effects on the activation energy for crystallization of a partially amorphized Ni-Mo alloy

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Sanchez, R.; Estrada-Guel, I.; Torre, S.D. de la; Gaona-Tiburcio, C. [Centro de Investigacion en Materiales Avanzados (CIMAV), Chihuahua (Mexico); Jaramillo-Vigueras, D. [Inst. Politecnico Nacional, ESIQIE, UPALM, Mexico (Mexico); Guerrero-Paz, J. [Centro de Investigaciones en Materiales y Metalurgia, Univ. Autonoma del Estadode Hidalgo (Mexico)

    2002-07-01

    The Mo system processed through mechanical alloying (MA) technique has been widely investigated. For the composition Mo-47 at % Ni partially amorphous phase was obtained after 36 h milling time. Fe contamination was detected in the samples milled in a stainless steel container. Longer milling times have an important effect in the crystallization temperature. The peak temperature was shifted to lower temperatures as increases the milling time. Milling device, milling container, Fe and oxygen have an important effect in the rate of amorphization and in the activation energy (Q) for crystallization. Q values for samples milled under air atmosphere are lower than those observed in samples milled in argon atmosphere. (orig.)

  17. High Efficiency Triple-Junction Amorphous Silicon Alloy Photovoltaic Technology, Final Technical Report, 6 March 1998 - 15 October 2001

    Energy Technology Data Exchange (ETDEWEB)

    Guha, S.

    2001-11-08

    This report describes the research program intended to expand, enhance, and accelerate knowledge and capabilities for developing high-performance, two-terminal multijunction amorphous silicon (a-Si) alloy cells, and modules with low manufacturing cost and high reliability. United Solar uses a spectrum-splitting, triple-junction cell structure. The top cell uses an amorphous silicon alloy of {approx}1.8-eV bandgap to absorb blue photons. The middle cell uses an amorphous silicon germanium alloy ({approx}20% germanium) of {approx}1.6-eV bandgap to capture green photons. The bottom cell has {approx}40% germanium to reduce the bandgap to {approx}1.4-eV to capture red photons. The cells are deposited on a stainless-steel substrate with a predeposited silver/zinc oxide back reflector to facilitate light-trapping. A thin layer of antireflection coating is applied to the top of the cell to reduce reflection loss. The major research activities conducted under this program were: (1) Fundamental studies to improve our understanding of materials and devices; the work included developing and analyzing a-Si alloy and a-SiGe alloy materials prepared near the threshold of amorphous-to-microcrystalline transition and studying solar cells fabricated using these materials. (2) Deposition of small-area cells using a radio-frequency technique to obtain higher deposition rates. (3) Deposition of small-area cells using a modified very high frequency technique to obtain higher deposition rates. (4) Large-area cell research to obtain the highest module efficiency. (5) Optimization of solar cells and modules fabricated using production parameters in a large-area reactor.

  18. Local atomic structure of Zr-Cu and Zr-Cu-Al amorphous alloys investigated by EXAFS method

    International Nuclear Information System (INIS)

    Antonowicz, J.; Pietnoczka, A.; Zalewski, W.; Bacewicz, R.; Stoica, M.; Georgarakis, K.; Yavari, A.R.

    2011-01-01

    Research highlights: → Coordination number, interatomic distances and mean square atomic displacement in Zr-Cu and Zr-Cu-Al glasses. → Icosahedral symmetry in local atomic structure. → Deviation from random mixing behavior resulting from Al addition. - Abstract: We report on extended X-ray absorption fine structure (EXAFS) study of rapidly quenched Zr-Cu and Zr-Cu-Al glassy alloys. The local atomic order around Zr and Cu atoms was investigated. From the EXAFS data fitting the values of coordination number, interatomic distances and mean square atomic displacement were obtained for wide range of compositions. It was found that icosahedral symmetry rather than that of corresponding crystalline analogs dominates in the local atomic structure of Zr-Cu and Zr-Cu-Al amorphous alloys. Judging from bonding preferences we conclude that addition of Al as an alloying element results in considerable deviation from random mixing behavior observed in binary Zr-Cu alloys.

  19. Electric charging/discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons.

    Science.gov (United States)

    Fukuhara, Mikio; Sugawara, Kazuyuki

    2014-01-01

    Charging/discharging behaviors of de-alloyed and anodic oxidized Ti-Ni-Si amorphous alloy ribbons were measured as a function of current between 10 pA and 100 mA, using galvanostatic charge/discharging method. In sharp contrast to conventional electric double layer capacitor (EDLC), discharging behaviors for voltage under constant currents of 1, 10 and 100 mA after 1.8 ks charging at 100 mA show parabolic decrease, demonstrating direct electric storage without solvents. The supercapacitors, devices that store electric charge on their amorphous TiO2-x surfaces that contain many 70-nm sized cavities, show the Ragone plot which locates at lower energy density region near the 2nd cells, and RC constant of 800 s (at 1 mHz), which is 157,000 times larger than that (5 ms) in EDLC.

  20. 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

  1. Magnetic and Mössbauer studies of Fe76Mo8Cu1B15 amorphous alloy

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Maryško, M.; Miglierini, M.

    54, Suppl. D, - (2004), s. D77-D80 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism /12./. Kosice, 12.07.2004-15.07.2004] R&D Projects: GA AV ČR IBS2041105; GA ČR GA106/02/0943 Institutional research plan: CEZ:AV0Z2041904 Keywords : Amorphous alloy * Mössbauer spectroscopy * magnetizationCzech and Slovak Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.292, year: 2004

  2. Large Magnetocaloric Effect Around Room Temperature in Amorphous Fe-Gd-Zr Alloy Ribbon with Short-Range Interactions

    Science.gov (United States)

    Thanh, Tran Dang; Yen, Nguyen Hai; Duc, Nguyen Huu; Phan, The-Long; Dan, Nguyen Huy; Yu, Seong-Cho

    2016-05-01

    In this work, we present a detailed study on the magnetocaloric effect and the critical behaviors of an amorphous Fe88Gd2Zr10 alloy ribbon prepared by using a rapid quenching method. We point out that the value of maximum magnetic entropy change (|Δ S max|) of amorphous Fe88Gd2Zr10 alloy ribbon appeared at near room temperature and versus Δ H obeys a power law, |Δ S max| = a·Δ H n. In addition, all Δ S m( T, Δ H) data measured at different Δ H values are collapsed onto a universal master curve. Interestingly, M 2 versus H/ M curves prove amorphous Fe88Gd2Zr10 ribbon exhibitied a second-order magnetic phase transition. The critical exponents ( β, γ, and δ) obtained from the modified Arrott plots and the Kouvel-Fisher methods, and critical isotherm analysis are very close to those expected for the 3D-Heisenberg model, proving ferromagnetic short-range interactions exist in amorphous Fe88Gd2Zr10 ribbon.

  3. In vitro metal ion release and biocompatibility of amorphous Mg67Zn28Ca5 alloy with/without gelatin coating.

    Science.gov (United States)

    Chan, W Y; Chian, K S; Tan, M J

    2013-12-01

    Amorphous zinc-rich Mg-Zn-Ca alloys have exhibited good tissue compatibility and low hydrogen evolution in vivo. However, suboptimal cell-surface interaction on magnesium alloy surface observed in vitro could lead to reduced integration with host tissue for regenerative purpose. This study aims to improve cell-surface interaction of amorphous Mg67Zn28Ca5 alloy by coating a gelatin layer by electrospinning. Coated/uncoated alloys were immersed and extracted for 3 days under different CO2. The immersion results showed that pH and metal ion release in the alloy extracts were affected by gelatin coating and CO2, suggesting their roles in alloy biocorrosion and a mechanism has been proposed for the alloy-CO2 system with/without coating. Cytotoxicity results are evident that gelatin-coated alloy with 2-day crosslinking not only exhibited no indirect cytotoxicity, but also supported attachment of L929 and MG63 cell lines around/on the alloy with high viability. Therefore, amorphous Mg67Zn28Ca5 alloy coated with gelatin by electrospinning technique provides a useful method to improve alloy biocompatibility. © 2013 Elsevier B.V. All rights reserved.

  4. Preparation of magnetic Ni-P amorphous alloy microspheres and their catalytic performance towards thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Deng, Yi; Yang, Yuanyi; Ge, Liya; Yang, Weizhong; Xie, Kenan

    2017-12-01

    In this work, a series of amorphous Ni-P alloys with diverse microspheric structures and magnetic properties were successfully prepared through a facile aqueous solution reduction using sodium hypophosphite as reducing agent with the assistance of polyvinylpyrrolidone (PVP). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and laser particle size analysis were used to investigate the structure of Ni-P alloy particles, which demonstrated that the as-prepared alloys possessed spherical morphologies and tunable compositions. We investigated the effects of the synthesis conditions including reaction temperature, initial Ni2+ concentration, pH value, and surfactant type on the morphologies and chemical constitutes of Ni-P alloy particles. Compared with other microsphere counterparts (ferromagnetism), the spherical Ni-P alloy powders with diameter of about 500 nm exhibited apparent paramagnetism. In addition, the catalytic performance of the products on the thermal decomposition of ammonium perchlorate (AP) was further investigated via thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). These Ni-P noncrystalline alloy particles with different magnetic properties and good catalytic activities would broaden the technological and industrial applications of Ni-P alloys in petrochemical reaction, soft magnetic devices, and burning rate catalysts.

  5. Stability of an amorphous alloy of the Mm-Al-Ni-Cu system

    Directory of Open Access Journals (Sweden)

    Carlos Triveño Rios

    2012-10-01

    Full Text Available An investigation was made of the stability of melt-spun ribbons of Mm55Al25Ni10Cu10 (Mm = Mischmetal amorphous alloy. The structural transformations that occurred during heating were studied using a combination of X-ray diffraction (XRD and differential scanning calorimetry (DSC. Crystallization took place through a multi-stage process. The first stage of transformation corresponded to the formation of a metastable phase followed by cfc-Al precipitation, while in the second stage, exothermic transformations led to the formation of complex and unidentified Mm(Cu, Ni and MmAl(Cu, Ni phases. The transformation curves recorded from isothermal treatments at 226 °C and 232 °C indicated that crystallization occurred through nucleation and growth, with diffusion-controlled growth occurring in the first crystallization stage. The supercooled liquid region, ∆Tx, at 40 K/min was ~80 K. This value was obtained by the substitution of Mm (=Ce + La + Nd + Pr for La or Ce, saving chemical element-related costs.

  6. Spin dynamics of an amorphous Ysub(0.33)Fesub(0.67) alloy

    International Nuclear Information System (INIS)

    Murani, A.P.; Rebouillat, J.P.

    1982-01-01

    Neutron inelastic scattering measurements are reported of the amorphous spin-glass alloy Ysub(0.33)Fesub(0.67). A broad inelastic (quasi-elastic) spectral response, centred about zero energy transfer and a resolution-limited central 'elastic' peak, is observed at all temperatures down to 5 K, the lowest temperature in the study. Both the 'elastic' scattering and the integrated inelastic scattering are strongly peaked in the forward direction at all temperatures (5 -1 ). Additionally, the spectral width initially decreases with decreasing temperature goes through a minimum at a temperature somewhere above the temperature of the maximum in the susceptibility and increases again at lower temperatures. As the temperature decreases, however, the spectral intensity of the broad quasi-elastic response decreases steadily below a reasonably high temperature around 3 Tsub(sg) while the resolution-limited 'elastic' scattering intensity increases. Overall, the spin dynamics of the system bear strong resemblance to those of the CuMn spin glasses investigated earlier. (author)

  7. Mechanical spectroscopy studies of partially amorphous Nd60Fe30Al10 alloys

    International Nuclear Information System (INIS)

    Tarnowski, German C.; Salva, Horacio; Ghilarducci, Ada A.; Urreta, Silvia E.; Billoni, Orlando V.; Fabietti, Luis M.

    2004-01-01

    The hard magnetic properties of melt spun Nd 60 Fe 30 Al 10 alloys are attributed to a major matrix nominally amorphous for X-ray diffraction, composed by two metastable nanosized (∼5 nm) phases with different intrinsic magnetic properties. This composite system is investigated for the first time by mechanical spectroscopy techniques in the temperature range between 50 K and 450 K (1 kHz) where large annealing effects and two damping phenomena are detected. The as-cast microstructure irreversibly changes during annealing above 330 K, leading to a large modulus recovery accompanied by a reduction in the internal friction level. A relatively large relaxation effect is observed about 290 K, evidenced by a narrow internal friction peak with the corresponding step in the elastic modulus; this peak remains stable under thermal cycling between 200 K and 300 K but is affected by aging at 330 K and practically vanishes after heating to 450 K. Another internal friction peak is observed at about 250 K which has associated an anomalous modulus effect; in this temperature range, the internal friction and the elastic modulus exhibit heating/cooling hysteresis, which strongly depends on the extreme temperatures of the thermal cycle, a behavior frequently associated to first-order phase transformations

  8. Electrical properties and degradation behavior of hydrogenated amorphous Si alloys for solar cells

    Science.gov (United States)

    Krühler, W.; Kusian, W.; Karg, F.; Pfleiderer, H.

    1986-12-01

    The electrical properties and the degradation behavior of hydrogenated amorphous silicon alloys (a-Si1- x A x : H, with A=C, Ge, B, P) in designs of pin, pip, nin, and MOS structures are investigated by measuring the dark and light I(V) characteristics and the spectral response as well as the space-charge-limited current (SCLC), the time of flight (TOF) of carriers and the field effect (FE). These investigations give an overview of our recent work combined with new results emphasizing the physics of the a-Si:H pin solar cells. We discuss the stabilizing influence on the degradation behavior achieved by profiling the i layers of the pin solar cells with P and B. Two kinds of pin solar cells, namely glass/SnO2/p(C)in/metal and glass/metal/pin/ITO, are investigated and an explanation of their different spectral response behavior is given. SCLC measurements lead to the conclusion that trapping is also involved in the degradation mechanism, as is recombination. TOF experiments on a-Si1- x Ge x : H pin diodes indicate that the incorporation of Ge widens the tail-state distribution below the conduction band. FE measurements showed densities of gap states of about 5×l016cm-3eV-1.

  9. Amorphous oxide alloys as interfacial layers with broadly tunable electronic structures for organic photovoltaic cells.

    Science.gov (United States)

    Zhou, Nanjia; Kim, Myung-Gil; Loser, Stephen; Smith, Jeremy; Yoshida, Hiroyuki; Guo, Xugang; Song, Charles; Jin, Hosub; Chen, Zhihua; Yoon, Seok Min; Freeman, Arthur J; Chang, Robert P H; Facchetti, Antonio; Marks, Tobin J

    2015-06-30

    In diverse classes of organic optoelectronic devices, controlling charge injection, extraction, and blocking across organic semiconductor-inorganic electrode interfaces is crucial for enhancing quantum efficiency and output voltage. To this end, the strategy of inserting engineered interfacial layers (IFLs) between electrical contacts and organic semiconductors has significantly advanced organic light-emitting diode and organic thin film transistor performance. For organic photovoltaic (OPV) devices, an electronically flexible IFL design strategy to incrementally tune energy level matching between the inorganic electrode system and the organic photoactive components without varying the surface chemistry would permit OPV cells to adapt to ever-changing generations of photoactive materials. Here we report the implementation of chemically/environmentally robust, low-temperature solution-processed amorphous transparent semiconducting oxide alloys, In-Ga-O and Ga-Zn-Sn-O, as IFLs for inverted OPVs. Continuous variation of the IFL compositions tunes the conduction band minima over a broad range, affording optimized OPV power conversion efficiencies for multiple classes of organic active layer materials and establishing clear correlations between IFL/photoactive layer energetics and device performance.

  10. Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

    International Nuclear Information System (INIS)

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

    2005-01-01

    The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

  11. Extended x-ray absorption fine structure studies of amorphous and crystalline Si-Ge alloys with synchrotron radiation

    International Nuclear Information System (INIS)

    Kajiyama, Hiroshi

    1988-01-01

    Extended X-ray absorption fine structure (EXAFS) is a powerful probe to study the local structure around the atom of a specific element. In conventional EXAFS analysis, it has been known that reliable structures are obtained with the different values of absorption edge energy for different neighboring atoms. It is shown in this study that the Ge-K edge EXAFS resulting from the Ge-Ge and Ge-Si bonds in hydrogenated amorphous Si-Ge alloys was able to be excellently explained by a unique absorption edge energy value, provided that a newly developed formula based on the spherical wave function of photoelectrons is used. The microscopic structures of hydrogenated amorphous Si-Ge alloys and crystalline Si-Ge alloys have been determined using the EXAFS method. The lengths of Ge-Ge and Ge-Si bonds were constant throughout their entire composition range, and it was found that the length of Ge-Si bond was close to the average value of the bond lengths of both Ge and Si crystals. In crystalline Si-Ge alloys, it has been shown that the bonds relaxed completely, while the lattice constant varied monotonously with the composition. (Kako, I.)

  12. Local atomic structure and chemical order in amorphous SiGe:H and SiC:H alloys

    International Nuclear Information System (INIS)

    Pisarkiewicz, T.; Stapinski, T.

    1994-01-01

    The local structure and chemical ordering in amorphous hydrogenated silicon-germanium and silicon-carbon alloys were analyzed mainly with the help of extended x-ray absorption fine structure (EXAFS) spectroscopy, Raman scattering and electron diffraction. Ge-Ge and Ge-Si distances were found to be independent of concentration and the composition of the first coordination shell around Ge is consistent with a random mixing of the two species in a-Si 1-x Ge:H alloy. The first-coordination-shell average bond lengths for Si-Si and SiC in a-Si 1-x C x :H are also constant with concentration x and the comparison of the first coordination shell composition around Si with average concentration indicates that the alloys tends to be chemically ordered. The degree of crystallinity in microcrystalline Si films determined by EXAFS is in agreement with that obtained in Raman scattering analysis. (author). 16 refs, 5 figs

  13. Crystallization of the Al-Ni-Sm amorphous alloys; Cristalizacao de ligas amorfas no sistema Al-Ni-Sm

    Energy Technology Data Exchange (ETDEWEB)

    Danez, G.P., E-mail: gabidanez@hotmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Aliaga, L.C.R.; Kiminami, C.S.; Bolfarini, C.; Botta, W.J. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    Aluminum based amorphous alloys have received special attention due to unique properties such as high mechanical strength, corrosion, ductility and toughness as well as wear resistance. On the other hand, these properties can be improved by controlled crystallization of Al matrix with grain size ranged between 5 to 50 nanometers. The goal of this work was to study the thermal crystallization behavior of Al-Ni-Sm alloys. Compositions with the same topological instability ({lambda} = 0.1) were selected. Alloys were prepared in arc-melting furnace and ribbons were processed by melt-spinning technique. Samples ribbons were submitted to heating in order to induce crystallization, and its structure analyzed by x-ray diffraction. The difference in crystallization behavior is discussed in function of the topological instability due to the variation of the proportion of the transition metal to the rare-earth. (author)

  14. Amorphization and crystallization of Zr{sub 66.7-x}Cu{sub 33.3}Nb{sub x} (x = 0, 2, 4) alloys during mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yan [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, 73 Jingshi Road, Jinan 250061 (China); School of Materials Science and Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Chen Xiuxiu [School of Materials Science and Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Geng Haoran [School of Materials Science and Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China)], E-mail: mse_wangy@ujn.edu.cn; Yang Zhongxi [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, 73 Jingshi Road, Jinan 250061 (China); School of Materials Science and Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China)

    2009-04-17

    In the present paper, the effect of Nb and different rotation speeds on the amorphization and crystallization of Zr{sub 66.7-x}Cu{sub 33.3}Nb{sub x} (x = 0, 2, 4) alloys during mechanical alloying has been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The results show that the minor addition of Nb can shorten the start time of the amorphization reaction, improve the glass forming ability of Zr-Cu alloys, but cannot promote the formation of a single amorphous phase at a lower rotation speed of 200 rpm. The glass forming ability of the Zr{sub 66.7-x}Cu{sub 33.3}Nb{sub x} (x = 0, 2, 4) alloys increases with increasing Nb additions. At a higher rotation speed of 350 rpm, a single amorphous phase of Zr{sub 66.7-x}Cu{sub 33.3}Nb{sub x} (x = 0, 2, 4) can be successfully fabricated. Moreover, the Nb addition into Zr-Cu alloys can accelerate the amorphization process and improve the stability of the amorphous phase against the mechanically induced crystallization. Furthermore, the amorphous Zr{sub 66.7}Cu{sub 33.3} phase gradually transforms into a metastable fcc-Zr{sub 2}Cu phase with increasing milling time.

  15. A study of the diffusion mechanisms in amorphous metallic alloys: diffusion and diffusion under high pressure in an amorphous NiZr alloy; Contribution a l`etude des mecanismes de transport dans les materiaux metalliques amorphes: diffusion et diffusion sous pression dans NiZr amorphe

    Energy Technology Data Exchange (ETDEWEB)

    Grandjean, A.

    1996-03-01

    The aim of this work is a better understanding of the diffusion mechanism in amorphous metallic alloys. Then interdiffusion and hafnium diffusion in amorphous NiZr alloy have been studied. Samples used are made by sputtering co-deposition under vacuum and are well relaxed before the diffusion measurements. The time evolution of resistivity during annealing due to the decay of a composition modulated film has been measured and from this change in resistivity interdiffusion coefficients have been determined. Dependence of Hf diffusion on temperature and pressure has been studied using (SIMS). In this two cases, the diffusion process obeys an Arrhenius law and gives an activation energy of 1.33 eV for interdiffusion, and 0.76 eV for Hf diffusion. An effect of pressure on Hf diffusion has been found leading to an activation volume of 8.5 angstrom{sup 3}. Thanks to these results, two approaches of the diffusion mechanisms in these systems have been proposed. The first comes from a comparison with the diffusion mechanisms in crystalline metals, that is to say by point defects. The second is an hypothesis of collective motions in these non crystalline alloys. (author).

  16. Effects of annealing on the microstructure and magnetic property of the mechanically alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoxia; Zhou, Xuan; Yu, Shuaishuai; Wei, Congcong; Xu, Jing; Wang, Yan, E-mail: mse_wangy@ujn.edu.cn

    2017-05-15

    The effects of annealing treatment on the microstructure, thermal stability, and magnetic properties of the mechanical alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys (HEAs) have been investigated in this project. The simple crystallization products in FeSiBAlNi amorphous HEAs with Co and Ag addition reveal the high phase stability during heating process. At high annealing treatment, the crystallized HEAs possess the good semi-hard magnetic property. It can conclude that crystallization products containing proper FeSi-rich and FeB-rich phases are beneficial to improve the magnetic property. Annealing near the exothermic peak temperature presents the best enhancing effect on the semi-hard magnetic property of FeSiBAlNiCo. It performs both large saturated magnetization and remanence ratio of 13.0 emu/g and near 45%, which exhibit 465% and 105% enhancement compared with as-milled state, respectively. - Highlights: • Co, Cu, Ag additions affect crystallization behavior of FeSiBAlNi amorphous HEAs. • Crystallization products in FeSiBAlNi Co/Ag reveal high phase stability. • Proper FeSi-rich and FeB-rich phases are beneficial to improve magnetic property. • Annealing treatment improves semi-hard magnetic property compared to as-milled state. • Annealing near exothermic peak temperature shows best enhancing effect on magnetism.

  17. Towards tunable and multifunctional interfaces: Multicomponent amorphous alloys and bilayer stacks

    Science.gov (United States)

    Kast, Matthew G.

    Controlling the electronic structure and requisite charge transfer at and across interfaces is a grand challenge of materials science. Despite decades of research and numerous successes in the fields microelectronics and photovoltaics much work remains to be done. In many applications, whether they be in microelectronics, photovoltaics or display technology there is a demand for multiple functions at a single interface. Historically, existent materials were either discarded as an option due to known properties or tested with some application based figure of merit in mind. Following this, the quality of the material and/or the preparation of the surface/interface to which the material would be deposited was optimized. As the microelectronics and photovoltaics industries have matured, continued progress (faster, lower power transistors and more efficient, cheaper, abundant solar cells) will require new materials (possibly not previously existent) that are fundamentally better for their application than their highly optimized existent counter parts. The manifestation of this has been seen in the microelectronics field with introduction of hafnium silicates to replace silica (which had previously been monumentally successful) as the gate dielectrics for the most advanced transistors. Continued progress in efficient, cheap, abundant photovoltaics will require similar advances. Advances will be needed in the area of new abundant absorbers that can be deposited cheaply which result in materials with high efficiencies. In addition, selective contacts capable of extracting charge from efficient absorbers with low ohmic losses and low recombination rates will be needed. Presented here are two approaches to the multifunctional interface problem, first the use of amorphous alloys that open up the accessible composition space of thin films significantly and second the use of bilayers that loosen the requirements of a single film at an interface.

  18. Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

    International Nuclear Information System (INIS)

    Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

    2011-01-01

    Composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 was prepared by mechanical milling starting with nanocrystalline Mg 2 Ni and amorphous Mg 50 Ni 50 powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg 50 Ni 50 improved the hydriding and dehydriding kinetics of Mg 2 Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: → First study of the hydriding behavior of composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 . → Microstructural characterization of composite material using XRD and SEM was obtained. → An improved effect of Mg 50 Ni 50 on the Mg 2 Ni hydriding behavior was verified. → The apparent activation energy for the hydrogen desorption of composite was obtained.

  19. Thermal stability and glass-forming ability of amorphous Nd-Al-TM (TM=Fe, Co, Ni or Cu) alloys

    International Nuclear Information System (INIS)

    Inoue, A.; Zhang Tao

    1997-01-01

    Bulk amorphous alloys were prepared for Nd 70 Al 10 TM 20 and Nd 60 Al 10 TM 30 (TM=Fe or Co) alloys by copper mold casting. The maximum sample thickness for glass formation reaches 15 mm for the Nd-Al-Fe alloys and 5 mm for the Nd-Al-Co alloys. A significant difference in the phase transition upon heating is recognized between the Fe- and Co-containing alloys. No glass transition before crystallization is observed for the Nd-Al-Fe alloys, but the Nd-Al-Co alloys exhibit the glass transition. The ΔT x (=T x -T g ) and T g /T m are 40-55 K and 0.65-0.67, respectively, for the latter alloys. The absence of supercooled liquid for the former alloys is different from those for all bulk amorphous alloys reported up to date. The T x /T m and ΔT m (=T m -T x ) are 0.85-0.89 and 88-137 K, respectively, for the Nd-Al-Fe alloys and, hence, the large glass-forming ability is presumably due to the high T x /T m and small ΔT m values. (orig.)

  20. Structural investigations on an amorphous Se90Te10 alloy produced by mechanical alloying using EXAFS, cumulant expansion and RMC simulations.

    Science.gov (United States)

    Kostrzepa, I M; Siqueira, M C; Machado, K D; Maciel, G A; Sanchez, D F; Brunatto, S F

    2012-03-28

    We investigated an amorphous Se(90)Te(10) alloy produced by mechanical alloying using two different approaches. First, we used extended x-ray absorption fine structure (EXAFS) spectroscopy and the cumulant expansion method using the Einstein model for the temperature dependence of the cumulants to obtain the cumulants C(*)(1), C(*)(2), and C(*)(3). From these, we found information about the structure of the alloy as well as the thermal and structural disorder, anharmonicity of the effective interatomic pair potentials, thermal expansion of the Se-Se and Se-Te bonds and asymmetry of the partial distribution functions g(Se-Se)(r) and g(Se-Te)(r). The cumulants C(*)(1), C(*)(2), and C(*)(3) also allowed us to reconstruct the g(EXAFS)(ij)(r,T) functions from EXAFS. Then, we made reverse Monte Carlo (RMC) simulations using the total structure factor S(K) obtained from synchrotron x-ray diffraction and the EXAFS oscillations χ(k) on the Se K edge as input data to obtain the g(RMC)(ij)(r) functions. Both methods furnished very similar g(ij)(r) functions, and the structural data obtained from them were also very similar. The results obtained from both methods showed the presence of Se-Te pairs indicating that there is alloying at the atomic level. In addition, we could not find any evidence of the presence of Te clusters in the alloy. © 2012 IOP Publishing Ltd

  1. Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys

    Science.gov (United States)

    Kalb, J.; Spaepen, F.; Wuttig, M.

    2004-06-01

    Ex situ atomic force microscopy in combination with a high-precision furnace has been employed for a systematic study of crystallization kinetics of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5, and Ge2Sb2Te5 thin films used for optical data storage. Direct observation of crystals enabled us to establish the temperature dependence of the crystal nucleation rate and crystal growth velocity around 150°C. While these alloys exhibited similar crystal growth characteristics, the crystal nucleation behavior of Ag0.055In0.065Sb0.59Te0.29 differed significantly from that of Ge4Sb1Te5 and Ge2Sb2Te5. These observations provide an explanation for the different recrystallization mechanisms observed upon laser heating of amorphous marks.

  2. Nanocrystalline FeSiBNbCu alloys: Differences between mechanical and thermal crystallization process in amorphous precursors

    International Nuclear Information System (INIS)

    Lopez, M.; Marin, P.; Agudo, P.; Carabias, I.; Venta, J. de la; Hernando, A.

    2007-01-01

    Nanocrystalline magnetic particles obtained by high energy ball milling of FeSiBNbCu alloy were prepared from rapidly quenched ribbons as a starting material. Structural characterization was made by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and Moessbauer spectroscopy. The structural changes observed in this amorphous material suggest that nanocrystallization process takes place in a different way from the one induced by thermal treatments. Our different studies reveals that after short grinding times (up to 40 h) the material is composed by a two phase system of very fine nanocrystals embedded in a residual amorphous phase, while for largest periods of milling (from 140 h) the sample consists of a very fine nanocrystalline phase with a large fraction of grain boundary

  3. A study of the diffusion mechanism in glasses: a theoretical and experimental study of tracers diffusion in amorphous metallic alloys

    International Nuclear Information System (INIS)

    Loirat, Yanick

    1999-01-01

    The principal aims of this work are a better understanding of the experimental situation in amorphous metallic alloys and a tentative explanation of the role of collective mechanisms in matter transport. Self- and solute-diffusion of Hf, Au and Cu tracers in amorphous Ni Zr alloy have been studied. We study by SIMS analysis the broadening of the concentration profile with temperature and pressure, in thin amorphous layers which were prepared by sputtering and properly relaxed. The diffusion coefficient variation with temperature shows an Arrhenius behaviour for all of our tracers. The activation energy amount to 1.55 eV for Cu, 1.65 eV for Au and 1.78 eV for Hf and corresponds to nearly one half of the corresponding energy in crystalline zirconium. The diffusion coefficients variation with hydrostatic pressure yields an activation volume equal to one half of an average atomic volume of our matrix for medium and large sized tracers Au, Hf and a smaller activation volume for Cu. The second part of our work consists of numerical simulations of atomic displacements in a generic glass by two complementary methods. In a Lennard-Jones alloy with size effect, we observe by molecular dynamics (MD) some correlated displacements which consist of substitution cycles or chains. The associated energy of these collective events represents nearly 15 pc of that found in crystalline Lennard- Jones. The systematic exploration of energy surface in space configuration made with activation-relaxation technique ART yields energy distributions of stable and saddles positions and opens the way to an evaluation of diffusion coefficients. The events found by ART are qualitatively close to MD ones, but the averaged activation energy associated with these events represents only 10 pc of the crystalline one. This clearly points towards the limit of Lennard-Jones potential, which is not enough representative of actual glasses. This is the reason why an interaction model closer to amorphous

  4. 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.

  5. Electrical and magnetic properties of Fe-based bulk metallic glass with minor Co and Ni addition

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H.Y. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); Stoica, M. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); POLITEHNICA University of Timisoara, P-ta Victoriei 2, Timisoara (Romania); Yi, S. [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, 702–701 Daegu (Korea, Republic of); Kim, D.H. [Center for Non-crystalline Materials, Department of Metallurgical Engineering, Yonsei University, 120–749 Seoul (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); University of Technology Dresden, Institute of Materials Science, D–01062 Dresden (Germany)

    2014-09-01

    The effect of minor Co and Ni alloying on soft magnetic properties and electrical resistivity of Fe{sub 75.5}C{sub 7.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} (at%) bulk metallic glass has been investigated. Within examined compositional range (Co and Ni up to 4 at%, respectively), the saturation magnetization and electrical resistivity of the alloys continuously decrease with increasing Co or Ni content, while the Curie temperature and initial permeability increase. Comparing the effect of Co and Ni additions, the alloys with Co addition have much higher Curie temperature and saturation magnetization than the alloy with Ni addition. Also, the Co-added alloys show smaller coercivity and larger permeability than the Ni-added alloys. The present results suggest that minor addition of Co can provide better effectiveness to enhance the magnetic softness of Fe-based BMGs than minor Ni addition. - Highlights: • Soft magnetic characteristics of CI-based BMGs can be enhanced with minor Co and Ni alloying. • Minor Co addition can provide better effectiveness to enhance the magnetic softness of CI-based BMG than Ni addition. • Optimum Co addition enlarges atomic packing density and randomness of amorphous structure.

  6. Neutron-diffraction study and modeling of the lattice parameters of a NiAl-precipitate-strengthened Fe-based alloy

    International Nuclear Information System (INIS)

    Teng, Z.K.; Ghosh, G.; Miller, M.K.; Huang, S.; Clausen, B.; Brown, D.W.; Liaw, P.K.

    2012-01-01

    The lattice misfit between the body-centered cubic α-Fe matrix and the B2-ordered NiAl-type β′ precipitates is a parameter of significant importance in controlling the creep resistance of precipitate-strengthened ferritic steels. However, the measurement of the lattice misfit is complicated due to the fact that the fundamental reflections of α and β′ phases almost completely overlap. In this study, neutron diffraction is used to determine the lattice parameters of these two phases in a Fe–18.9 Al–9.8 Cr–13 Ni–1.8 Mo (atomic percent, at.%) alloy as a function of temperature. The accuracy of the measurement at room temperature is verified by high-energy synchrotron X-ray diffraction. The comparison between these two techniques is discussed in terms of the difference in superlattice intensity. Furthermore, using the phase compositions determined by atom probe tomography, models are proposed to predict the lattice parameters of both phases at room temperature as a function of their compositions. The results are in very good agreement with those obtained experimentally.

  7. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    Energy Technology Data Exchange (ETDEWEB)

    Rodionova, V. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); National University of Science and Technology “MISIS”, Leninsky prospect 4, Moscow 119049 (Russian Federation); Baraban, I.; Chichay, K.; Litvinova, A. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); Perov, N. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991 (Russian Federation)

    2017-01-15

    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of “classic” Fe{sub 77.5}Si{sub 7.5}B{sub 15} alloy with positive magnetostriction coefficient.

  8. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    International Nuclear Information System (INIS)

    Rodionova, V.; Baraban, I.; Chichay, K.; Litvinova, A.; Perov, N.

    2017-01-01

    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of “classic” Fe 77.5 Si 7.5 B 15 alloy with positive magnetostriction coefficient.

  9. Reverse Monte Carlo simulations, Raman scattering, and thermal studies of an amorphous Ge30Se70 alloy produced by mechanical alloying.

    Science.gov (United States)

    Machado, K D; de Lima, J C; Campos, C E M; Grandi, T A; Pizani, P S

    2004-01-01

    The short- and intermediate-range orders of an amorphous Ge30Se70 alloy produced by mechanical alloying were studied by reverse Monte Carlo simulations of its x-ray total structure factor, Raman scattering, and differential scanning calorimetry. The simulations were used to compute the G(Ge-Ge) (RMC)(r), G(Ge-Se) (RMC)(r), and G(Se-Se) (RMC)(r) partial distribution functions and the S(Ge-Ge) (RMC)(K), S(Ge-Se) (RMC)(K), and S(Se-Se) (RMC)(K) partial structure factors. We calculated the coordination numbers and interatomic distances for the first and second neighbors and the bond-angle distribution functions Theta(ijl)(cos theta). The data obtained indicate that the structure of the alloy has important differences when compared to alloys prepared by other techniques. There are a high number of Se-Se pairs in the first shell, and some of the tetrahedral units formed seemed to be connected by Se-Se bridges. (c) 2004 American Institute of Physics

  10. Thermal treatment of the Fe78Si9B13 alloy in it amorphous phase studied by means of Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Cabral P, A.; Lopez, A.; Garcia S, F.

    2003-01-01

    The magnetic and microhardness changes, dependents of the temperature that occur in the Fe 78 Si 9 B 13 alloy in it amorphous state were studied by means of the Moessbauer spectroscopy and Vickers microhardness. According to the Moessbauer parameters and in particular that of the hyperfine magnetic field, this it changes according to the changes of the microhardness; i.e. if the microhardness increases, the hyperfine magnetic field increases. The registered increment of hardness in the amorphous state of this alloy should be considered as anomalous, according to the prediction of the Hall-Petch equation, the one that relates negative slopes with grain sizes every time but small. (Author)

  11. Quantitative description of the magnetization curves of amorphous alloys of the series a-Dy xGd 1-xNi

    Science.gov (United States)

    Barbara, B.; Amaral, V. S.; Filippi, J.

    1992-10-01

    The magnetization curves of the series of amorphous alloys Dy xGd 1- xNi measured between 1.5 and 4.2 K and up to 15 T, have been fitted to the zero kelvin analytical model of Chudnovsky [1]. The results of these fits allow a detailed understanding of the magnetization curves of amorphous alloys with ferromagnetic interactions. In particular, the ratio D/ J of the local anisotropy and exchange energies, and the magnetic and atomic correlation lengths, are accurately determined.

  12. The Effect of Substitution of Fe By Co on Rapidly Quenched (FeCoMoCuB Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Marek Paluga

    2005-01-01

    Full Text Available (Fe1-xCox79Mo8Cu1B15 amorphous alloys ware prepared in the form of ribbons by rapid quenching for x=0. 0.25 and 0.5. The effect of variation of Co/Fe ratio is analyzed with respect to the formation of amorphous state and to transformation of the structure into nancrystalline phases formed after subsequent thermal treatment. Selected properties and atomic structure in as-quenched state are studied by TEM, AFM, XRD any by measurement of magnetoresistance characteristics. The influence of heat treatment on transport and magnetic properties is shown on temperature dependencies of electrical resistivity and magnetization. It was founf that while the increase of Co content leads to the increase of Curie temperature of as-quenched structure, transition to nanocrystalline state is not affected in a significant manner. The as-quenched state for alloy without Co was found to contain thin crystal-containing layer which, however, was observed, contary to general behavior, at the side of the ribbon exposed to higher quenching rates.

  13. The Chemically-Specific Structure of an Amorphous Molybdenum Germanium Alloy by Anomalous X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, H. A.

    2002-06-11

    Since its inception in the late 1970s, anomalous x-ray scattering (AXS) has been employed for chemically-specific structure determination in a wide variety of noncrystalline materials. These studies have successfully produced differential distribution functions (DDFs) which provide information about the compositionally-averaged environment of a specific atomic species in the sample. Despite the wide success in obtaining DDFs, there are very few examples of successful extraction of the fully-chemically-specific partial pair distribution functions (PPDFs), the most detailed description of an amorphous sample possible by x-ray scattering. Extracting the PPDFs is notoriously difficult since the matrix equation involved is ill-conditioned and thus extremely sensitive to errors present in the experimental quantities that enter the equation. Instead of addressing this sensitivity by modifying the data through mathematical methods, sources of error have been removed experimentally: A focusing analyzer crystal was combined with a position-sensitive linear detector to experimentally eliminate unwanted inelastic scattering intensity over most of the reciprocal space range probed. This instrumentation has been used in data collection for the extraction of PPDFs from amorphous (a)-MoGe{sub 3}. This composition arises as a phase separation endpoint in the Ge-rich region of the vapor-deposited Mo-Ge amorphous alloy system but is not present at equilibrium. Since the first Ge-rich compound in the Mo-Ge equilibrium system is MoGe{sub 2}, previous workers have speculated that perhaps a unique MoGe{sub 3} compound exists in the amorphous system. Rather than indicating a distinct MoGe{sub 3} compound with definitive local structure, however, the coordination results are more consistent with a densely-packed alloy having a wide range of solid solubility. Significant improvement in the quality and reliability of experimental PPDFs from a-MoGe{sub 3} by AXS has been achieved solely

  14. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  15. 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.)

  16. Reversible structural relaxation in melt-spun Co80-xCrxB20 (x=20, 25 or 30) amorphous alloys

    NARCIS (Netherlands)

    Haruyama, O; Ocelik, [No Value; Asahi, N; Ocelik, Vaclav

    1996-01-01

    The structural relaxation in melt-spun Co80-xCrxB20 (x=20, 25 or 30) amorphous alloys was investigated by measuring the residual electrical resistance (liquid-N-2 temperature). The reversibility, the specific logarithmic kinetics and the cross-over effect were confirmed for the chemical short-range

  17. Reversible amorphous-crystalline phase changes in a wide range of Se1-xTex alloys studied using ultrafast differential scanning calorimetry

    NARCIS (Netherlands)

    Vermeulen, Paul. A.; Momand, Jamo; Kooi, Bart J.

    The reversible amorphous-crystalline phase change in a chalcogenide material, specifically the Se1-xTex alloy, has been investigated for the first time using ultrafast differential scanning calorimetry. Heating rates and cooling rates up to 5000 K/s were used. Repeated reversible

  18. 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.

  19. Nanocrystallization in Co67Cr7Fe4Si8B14 Amorphous Alloy Ribbons

    Directory of Open Access Journals (Sweden)

    Zahra Jamili-Shirvan

    2013-12-01

    Full Text Available The nanocrystallization of Co67Fe4Cr7Si8B14 amorphous ribbons which prepared by planar flow melt spinning process (PFMS was investigated. Crystallization of the ribbons was studied by differential thermal analysis (DTA, X-ray diffraction (XRD and transmission electron microscopy (TEM. The DTA result of amorphous ribbon at heating rate of 10˚C/min showedoccurrence of phase transitions in two stages. The ribbons were isothermally annealed for 30 minutes in argon atmosphere at different temperatures between 300 and 650ºC with 25ºC steps. The magnetic properties of annealed samples were measured using a vibrating sample magnetometer (VSM. The VSM results revealed that optimum soft magnetic properties occurred at 400ºC. XRD patterns showed that the samples isothermally annealed up to 450ºC were amorphous, while TEM results at 400ºC indicated 7-8 nm mean size nanocrytallites in amorphous matrix and size of the nanocrystallites increased by increasing temperature. Also by X-ray diffraction pattern, precipitation of different phases at higher temperatures confirmed.

  20. Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

    DEFF Research Database (Denmark)

    Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.

    2000-01-01

    and temporal numerical simulation of that process. It is concluded that good thermal contact is maintained between the amorphous part of the solidified sample and the mould, while a rather poor contact develops between the crystalline part of the sample and the mould, probably due to the appearance of a narrow...... gap at the crystal-mould interface during crystallisation. The maximum amorphous layer thickness decreases from similar to3 mm to zero when the Al content increases in the range from 0 to about y = 10%. The evolution of the microstructure of the initially amorphous phase was examined by x...... measurements to be 60-150 K/s, in agreement with estimates from the literature. The Vickers hardness (Hv) of the amorphous material for y = 2% is higher (similar to 360 kg/mm(2)) than for y = 0 (similar to 290 kg/mm(2)). On crystallisation the hardness of the latter material increases to the 400 kg/mm(2) level...

  1. Critical behavior of electrical resistivity in amorphous Fe–Zr alloys

    Indian Academy of Sciences (India)

    Heisenberg like ferromagnet behavior in asymptotic critical region or not. A complete understanding of the critical phenomena in amorphous systems, therefore demands a systematic experimental study on materials having varying degrees and types of quenched disorder. The specific heat measurement is the most ...

  2. Ultra small angle neutron scattering from amorphous Ni-Pd-P-alloys

    International Nuclear Information System (INIS)

    Hagenmayer, R.M.; Zeyen, C.M.E.; Lamparter, P.; Steeb, S.

    1993-01-01

    Using a neutron double crystal spectrometer, thin amorphous Ni-Pd-P-samples were investigated at very small Q-values (10 -5 A -1 ≤ Q ≤ 10 -3 A -1 ). The immersion method shows that the small angle scattering effect is mainly caused by surface scattering. (orig.)

  3. Upper critical fields and superconducting transition temperatures of some zirconium-base amorphous transition-metal alloys

    International Nuclear Information System (INIS)

    Karkut, M.G.; Hake, R.R.

    1983-01-01

    Superconducting upper critical fields H/sub c/2(T), transition temperatures T/sub c/, and normal-state electrical resistivities rho/sub n/ have been measured in the amorphous transition-metal alloy series Zr/sub 1-z/Co/sub x/, Zr/sub 1-x/Ni/sub x/, (Zr/sub 1-x/Ti/sub x/)/sub 0.78/Ni/sub 0.22/, and (Zr/sub 1-x/Nb/sub x/)/sub 0.78/Ni/sub 0.22/. Structural integrity of these melt-spun alloys is indicated by x-ray, density, bend-ductility, normal-state electrical resistivity, superconducting transition width, and mixed-state flux-pinning measurements. The specimens display T/sub c/ = 2.1--3.8 K, rho/sub n/ = 159--190 μΩ cm, and Vertical Bar(dH/sub c/2/dT)cVertical Bar = 28--36 kG/K. These imply electron mean free paths lroughly-equal2--6 A, zero-temperature Ginzburg-Landau coherence distances xi/sub G/0roughly-equal50--70 A, penetration depths lambda/sub G/0roughly-equal(7--10) x 10 3 A, and extremely high dirtiness parameters xi 0 /lroughly-equal300--1300. All alloys display H/sub c/2(T) curves with negative curvature and (with two exceptions) fair agreement with the standard dirty-limit theory of Werthamer, Helfand, Hohenberg, and Maki (WHHM) for physically reasonable values of spin-orbit-coupling induced, electron-spin-flip scattering time tau/sub so/. This is in contrast to the anomalously elevated H/sub c/2(T) behavior which is nearly linear in T that is observed by some, and the unphysically low-tau/sub so/ fits to WHHM theory obtained by others, for various amorphous alloys

  4. On the relation between quasi-static and dynamic stress induced reversible structural relaxation of amorphous alloys

    International Nuclear Information System (INIS)

    Krueger, P.; Stucky, T.; Boewe, M.; Neuhaeuser, H.

    1993-01-01

    Quasi-static stress relaxation and dynamic internal friction measurements of stress induced reversible structural relaxation were performed on the amorphous alloy Fe 40 Ni 40 B 20 . The kinetics can be well described by a stretched exponential Kohlrausch-Williams-Watts quasi-static relaxation. The thermally activated part of the internal friction shows an Arrhenius temperature behaviour for a fixed vibration frequency and an inverse power frequency behaviour for a fixed temperature. The activation energies calculated from the Arrhenius equation and from the frequency shift method are significantly different. In order to explain this discrepancy the relation between the quasi-static and the dynamic descriptions of the reversible relaxation is reexamined. In particular it is shown that these two activation energies are connected by the Kohlrausch exponent of the quasi-static relaxation. (orig.)

  5. D-shell of iron atom of the amorphous FeCr15B15 alloy effective charge change during the crystallization

    Science.gov (United States)

    Khmelevsky, Nikolay O.; Funtikov, Yuriy V.; Aksenenko, Anatoliy Yu.; Ilyukhina, Olga V.; Metel, Alexander S.

    2018-03-01

    An amorphous metal alloy of the FeCrB system was studied during the crystallization by thermal annealing. Such an alloy is a perspective candidate for the role of an intermediate layer in multilayer covering for cutting tools. By the using of the thermoelectric voltage measurement, positron annihilation spectroscopy, and X-ray photoelectron spectroscopy, the conjoint research was performed for the study of the conduction and d-electron band state in the amorphous metallic alloy FeCr15B15, which intersects each other by the energy. The results of all the studies agree with each other and indicate the change in the effective charge of the d-shell by 1 electron during crystallization.

  6. Fe-based composite materials with improved mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Werniewicz, Katarzyna [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland); Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland)

    2008-07-01

    Following a previous study by the authors two new compositions (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 91}C{sub 9} and (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} have been developed with the aim of improving the ductility of Fe{sub 65.5}Cr{sub 4}Mo{sub 4}Ga{sub 4}P{sub 12}C{sub 5}B{sub 5.5} bulk metallic glass (BMG). In contrast to the alloys in that study, the recently prepared Fe-based materials are Ga-free. It was expected that the variations in the composition will lead to the changes in the phase formation and, hence, in the mechanical response of the investigated alloys. It was recognized that in-situ formed Fe-based composites show superior plasticity ({epsilon}{sub pl}{approx}37%) for the alloy with lower C content and ({epsilon}{sub pl}{approx}4%) for the alloy with higher C content compared to monolithic glass ({epsilon}{sub pl}{approx}0.2%). Furthermore, on the basis of present as well as previous investigations it has been shown that the Ga addition is beneficial for the plasticity of these Fe-based alloys. It was observed that the (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} alloy exhibits a significantly smaller fracture strain ({epsilon}{sub f}{approx}5%) compared to its Ga-containing counterpart ({epsilon}{sub f}{approx}16%). Therefore, it can be concluded that appropriate alloying additions are crucial in enhancing the mechanical properties of the complex Fe-based materials developed here.

  7. Crystallization behavior and the thermal properties of Zr63Al7.5Cu17.5Ni10B2 bulk amorphous alloy

    International Nuclear Information System (INIS)

    Jang, J.S.C.; Chang, L.J.; Jiang, Y.T.; Wong, P.W.

    2003-01-01

    The ribbons of amorphous Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloys with 0.1 mm thickness were prepared by melt spinning method. The thermal properties and micro structural development during the annealing of amorphous alloy have been investigated by a combination of differential thermal analysis, differential scanning calorimetry, high-temperature optical microscope, X-ray diffractometry and TEM. The glass transition temperature for the Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloys are measured about 645 K (372 C). This alloy also obtains a large temperature interval ΔT x about 63 K. Meanwhile, the calculated T rg for Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloy presents the value of 0.57. The activation energy of crystallization for the alloy Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 was about 370± 10 kJ/mole as determined by the Kissinger and Avrami plot, respectively. These values are about 20% higher than the activation energy of crystallization for the Zr 65 Al 7.5 Cu 17.5 Ni 10 alloy (314 kJ/mol.). This implies that the boron additions exhibit the effect of improving the thermal stability for the Zr-based alloy. The average value of the Avrami exponent n were calculated to be 1.75±0.15 for Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloy. This indicates that this alloy presents a crystallization process with decreasing nucleation rate. (orig.)

  8. The influence of structural changes on electrical and magnetic characteristics of amorphous powder of the nixmoy alloy

    Directory of Open Access Journals (Sweden)

    Ribić-Zelenović Lenka

    2006-01-01

    Full Text Available Nickel and molybdenum alloy powder was electrodeposited on a titanium cathode from a NiSO4⋅7H2O and (NH46 Mo7O24⋅4H2O ammonium solution. The desired chemical composition, structure, size and shape of particles in the powder samples were achieved by an appropriate choice of electrolysis parameters (current density, composition and temperature of the solution, cathode material and electrolysis duration. Metal coatings form in the current density range 15 mA cm-2alloy decreases with the increase of the current density of deposition. Smaller sized particles form at higher current density. X-ray analysis, differential scanning calorimetric and measurements of the temperature dependence of electric resistance and magnetic permeability of the powder samples were all used to establish a predominantly amorphous structure of the powder samples formed at the current density of j≥70mA cm-2. The crystalline particle content in the powder samples increases with the decrease of the current density of deposition. Powder heating causes structural changes. The process of thermal stabilization of nickel and molybdenum amorphous powders takes place in the temperature interval from 463K to 573K and causes a decrease in electrical resistance and increase in magnetic permeability. The crystallization temperature depends on the value of current density of powder electrodeposition. Powder formed at j=180 mA cm-2 begins to crystallize at 573K, while the powder deposited at j=50 mA cm-2 begins to crystallize at 673K. Crystallization of the powder causes a decrease in electric resistivity and magnetic

  9. EFFECT OF THE TEMPERATURE ON THE FRICTION AND WEAR PROPERTIES OF BULK AMORPHOUS ALLOY

    OpenAIRE

    DAWIT ZENEBE SEGU; PYUNG HWANG; SEOCK-SAM KIM

    2014-01-01

    The present paper report the results of an experimental investigation of the temperature effect on the sliding friction and wear properties of the bulk metallic glass (BMG). To improve the friction and wear properties of the BMG, the disk specimens were developed in the alloy system of Fe67.6C7.1Si3.3B5.5P8.7Cr2.3Mo2.6Al2Co1.0 using hot metal and industrial ferro-alloys. The friction and wear test was performed using flat-on-flat contact configuration of unidirectional tribometer and Si3N4 ce...

  10. Comparison between Einstein and Debye models for an amorphous Ni46Ti54 alloy produced by mechanical alloying investigated using extended x-ray absorption fine structure and cumulant expansion.

    Science.gov (United States)

    Machado, K D

    2011-02-14

    We investigated an amorphous Ni(46)Ti(54) alloy produced by mechanical alloying using extended x-ray absorption fine structure (EXAFS) technique and cumulant expansion considering Einstein and Debye models for the temperature dependence of the cumulants. Results obtained from both models were compared and very similar values were obtained. From them, we found information about the structure of the alloy besides thermal and structural disorder, anharmonicity, thermal expansion, and asymmetry of the partial distribution functions g(ij)(r). The cumulants C(1)(*), C(2)(*), and C(3)(*) also allowed us to reconstruct the g(ij)(r, T) functions from EXAFS.

  11. Magnetic regimes in amorphous Ni--Fe--P--B alloys. [1. 7 to 300/sup 0/K

    Energy Technology Data Exchange (ETDEWEB)

    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/)/sub 79/P/sub 13/B/sub 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/sup 0/K are reported. The Ni/sub 79/P/sub 13/B/sub 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/sub 79/P/sub 13/B/sub 8/ alloy is ferromagnetic with a Curie temperature T/sub c/ of 616/sup 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.

  12. RETRACTED: Study on the magnetic viscosity of Nd45Pr15Fe30-xCoxAl10 (x=0, 10) bulk amorphous Alloys

    Science.gov (United States)

    Qi, Guoquan; Fan, Haiping; Wu, Gang; Song, Shengyin; Wei, Dong; Bai, Qiang

    2013-06-01

    The bulk amorphous Nd45Pr15Fe30-xCoxAl10 (x=0, 10) alloys, which were prepared by arc melting and investigated by XRD and VSM, present hard magnetic behavior at room temperature. The intrinsic coercivity of the bulk amorphous increased with increasing Co addition. A single sharp and narrow peak close to the coercivity appeared in the irreversible susceptibility (χirr) curve for each alloy. The addition of Co has little influence on the magnetic viscosity of the alloys. With the substitution of Co for Fe, the fluctuation field Hf increased from 9.9 mT to 11.5 mT, and the activation volume Va increased from 2.9×10-18 cm3 to 3.6×10-18 cm3, which leads to an increase of the activation diameter Da from 17.7 nm to 19.0 nm. The value of Da deduced from the magnetic viscosity measurements is similar to the size of clusters of Nd-based bulk amorphous alloys, which may be responsible for the hard magnetic property exhibited at room temperature.

  13. On the reproducibility of heterogeneous nucleation in amorphous Al{sub 85}Ni{sub 10}Ce{sub 5} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, P. [Oxford Univ. (United Kingdom). Dept. of Materials; Greer, A.L. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

    1997-06-15

    Amorphous aluminium alloys can be successfully used as a matrix in which to study heterogeneous nucleation of {alpha}-Al on embedded conventional grain-refiner particles. The nucleation potency of a particle can be estimated from the extent of Al crystal growth on the particle during the glass-forming quench. The extent of growth is, of course, also dependent on the exact quenching conditions. However, the devitrification behaviour of the amorphous matrix can be used as an indicator of the quenching conditions, thereby permitting a comparative study of the nucleation potency. (orig.)

  14. Pair distribution function and its relation to the glass transition in an amorphous alloy

    International Nuclear Information System (INIS)

    Basak, S.; Clarke, R.; Nagel, S.R.

    1979-01-01

    Data for the pair distribution function g (r) are presented as a function of temperature for amorphous Nb/sub 0.4/Ni/sub 0.6/. We show, based on a simple model, that g (r) varies linearly with T over a wide temperature range in the glass as was found empirically by Wendt and Abraham. We also find that in our glass the behavior of g (r) near the glass transition is, within experimental error, similar to what they found in their Monte Carlo calculation. We interpret the deviation from linearity at the glass transition as due to the onset of diffusive motion of the atoms

  15. Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

    International Nuclear Information System (INIS)

    Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

    2017-01-01

    The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments. - Highlights: •Corrosion of Zircaloy-4 joints brazed with Zr-Cu-X filler alloys was investigated. •Alloyed Al deteriorated the overall nobility of joints by microgalvanic reaction. •Compositional gradient of Al in joints was the driving force for galvanic corrosion. •Cu and Fe did not influence the electrochemical stability of joints. •Zr-Cu-Fe filler alloy yielded excellent high-temperature corrosion resistance.

  16. Design and fabrication of a mechanical alloying system for preparing intermetallic, nanocrystalline, amorphous and quasicrystalline compounds

    International Nuclear Information System (INIS)

    Bonifacio M, J.; Iturbe G, J.L.; Castaneda J, G.

    2002-01-01

    In this work a grinding system was designed and fabricated which allowed to improve the operation conditions in time, frequency, temperature and selection of the grinding media and that allow the contamination decrease of the compounds. By means of this method of mechanical alloying new metallic compounds can be produced, starting from elemental powders, with fine and controlled microstructures. These compounds prepared by this method are going to be used as materials for the hydrogen storage. (Author)

  17. Formation of carbon nanotubes on an amorphous Ni{sub 25}Ta{sub 58}N{sub 17} alloy film by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, D. G.; Dubkov, S. V., E-mail: sv.dubkov@gmail.com [National Research University of Electronic Technology MIET (Russian Federation); Pavlov, A. A. [Russian Academy of Sciences, Institute of Nanotechnologies of Microelectronics (Russian Federation); Skorik, S. N. [Technological Center Research and Production Complex (Russian Federation); Trifonov, A. Yu. [Lukin Scientific Research Institute of Physical Problems (Russian Federation); Kirilenko, E. P.; Shulyat’ev, A. S. [National Research University of Electronic Technology MIET (Russian Federation); Shaman, Yu. P. [Technological Center Research and Production Complex (Russian Federation); Rygalin, B. N. [National Research University of Electronic Technology MIET (Russian Federation)

    2016-12-15

    It is shown that it is possible to grow carbon nanotubes on the surface of an amorphous Ni–Ta–N metal alloy film with a low Ni content (~25 at %) by chemical deposition from acetylene at temperature 400–800°C. It is established that the addition of nitrogen into the Ni–Ta alloy composition is favorable for the formation of tantalum nitride and the expulsion of Ni clusters, which act as a catalyst of the growth of carbon nanotubes, onto the surface. From Raman spectroscopy studies, it is found that, as the temperature of synthesis is raised, the quality of nanotubes is improved.

  18. The difference between the crystallization processes induced by mechanical milling and annealing under normal and high pressure in amorphous Fe-N alloy

    CERN Document Server

    LiuLi; Guo Xing Yuan; Zhao Xu Dong; Yao Bin; Su Wen Hui

    2002-01-01

    An amorphous Fe-N alloy was prepared by ball milling a mixture of Fe and h-BN. Its crystallization processes induced by mechanical milling (MM) and annealing under normal and high pressure were studied. The crystallization product of the amorphous Fe-N alloy induced by MM and annealing at temperatures between 690 and 800 K under pressures of 3-4 GPa is epsilon-Fe sub x N, while the thermal crystallization product under normal pressure is gamma'-Fe sub 4 N. The difference between the crystallization products produced by mechanical and thermal crystallization is attributed to the effects of local pressure and local temperature produced by ball collisions.

  19. Positron annihilation Doppler broadening measurement for bulk amorphous alloy by using high energy positron generated from LCS gamma-ray at NEW SUBARU

    Science.gov (United States)

    Hori, F.; Ueno, Y.; Ishii, K.; Ishiyama, T.; Iwase, A.; Miyamoto, S.; Terasawa, T.

    2016-01-01

    A simple positron annihilation measurement apparatus via pair creation has been developed using high energetic gamma beam generated by laser Compton scattering (LCS) of 1 GeV electrons circulated in a storage ring and laser light with the power more than 1 W at the New SUBARU synchrotron radiation facility, University of Hyogo. This MeV ordered energy changeable positron apparatus is useful to study defects in bulk materials. In this study, the average energy of 8MeV positron was selected by the wavelength of laser light and circulated electron energy in photon factory. As a demonstrate of non-destruction positron measurement by this apparatus, positron annihilation Doppler broadening measurement has performed for bulk size of amorphous and crystal structured Zr based alloys. The larger Doppler broadening S parameter for amorphous alloy than that for crystallized one has been successfully measured.

  20. Structural and dynamical properties of the Cu{sub 46}Zr{sub 54} alloy in crystalline, amorphous and liquid state: A molecular dynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Valencia-Balvin, Camilo, E-mail: cavalen@fisica.udea.edu.c [Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); ITM Institucion Universitaria, A.A 54959 Medellin (Colombia); Loyola, Claudia [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Osorio-Guillen, Jorge [Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); Gutierrez, Gonzalo [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile)

    2010-12-15

    Molecular dynamics simulations for the crystal, amorphous and liquid Cu{sub 46}Zr{sub 54} alloy were carried out on a system with up to 2000 particles, using a pairwise potential of the Rosato-Guillope-Legrand type. All simulations were done in the microcanonical ensemble, for a initial density of 5.76 g/cm{sup 3}, at different temperatures. A detailed analysis has been made by means of the pair-correlation function, coordination number, angle distribution, diffusion coefficient and vibrational density of states. We compared the main peaks of the amorphous phase with experimental data, obtaining a good agreement. The analysis of coordination number for the amorphous phase shows that the main building block of this phase are distorted icosahedron.

  1. Low-temperature magnetic behaviour in amorphous and nanocrystalline Fe-Nb-B alloys

    International Nuclear Information System (INIS)

    Skorvanek, I.; Duhaj, P.; Groessinger, R.

    2000-01-01

    The low-temperature magnetic behaviour is studied in a series of heat-treated amorphous and nanocrystalline Fe 80.5 Nb 7 B 12.5 samples with different volume fractions of crystalline phase. The measurements of coercivity, initial susceptibility and magnetostriction have been performed in a temperature range between 1.5 and 300 K. The coercivity of nanocrystalline samples shows a minimum versus measuring temperature. The temperature of this minimum is shifted to lower temperatures with an increasing volume fraction of crystalline phase. A significant magnetic hardening characterized by abrupt upturn of coercivity is reported for all nanocrystalline samples in the temperature range below 30 K. The role of different factors in determining the low-temperature magnetic behaviour is discussed

  2. Influence of the microstructure on the corrosion behavior of magnetron sputter-quenched amorphous metallic alloys

    Science.gov (United States)

    Thakoor, A. P.; Khanna, S. K.; Williams, R. M.; Landel, R. F.

    1983-01-01

    The microstructure and corrosion behavior of magnetron sputter deposited amorphous metallic films of (Mo6ORu40)82B18 under varying sputtering atmospheres have been investigated. The microstructural details and topology of the films have been studied by scanning electron microscopy and correlated with the deposition conditions. By reducing the pressure of pure argon gas, the characteristic features of rough surface and columnar growth full of vertical voids can be converted into a mirror-smooth finish with very dense deposits. Films deposited in the presence of O2 or N2 exhibit columnar structure with vertical voids. Film deposited in pure argon at low pressure show remarkably high corrosion resistance due to the formation of a uniform passive surface layer. The influence of the microstructure and surface texture on the corrosion behavior is discussed.

  3. Molecular field analysis for melt-spun amorphous Fe sub 1 sub 0 sub 0 sub - sub x Gd sub x alloys (18<=60)

    CERN Document Server

    Yano, K

    2000-01-01

    The magnetic properties for the melt-spun amorphous Fe sub 1 sub 0 sub 0 sub - sub x Gd sub x alloys were analyzed using the molecular field theory (MFT). A concentration dependence of three exchange interaction constants was derived over a wide concentration range (18=T sub c sub o sub m sub p. Curvature of the Arrott plot in Gd-rich region was qualitatively simulated.

  4. Nuclear and magnetic medium range order in amorphous Tb65Cu35 and Er69.5Cu30.5 alloys

    International Nuclear Information System (INIS)

    Boucher, B.; Sanquer, M.; Tourbot, R.

    1989-01-01

    Small angle neutron scattering on amorphous and mechanical polished Tb 65 Cu 35 and Er 69.5 Cu 30.5 alloys has been measured at different temperatures between 4 and 300K on samples cooled in zero or in applied magnetic fields. The isotropic scattering is analyzed quantitatively in terms of spatial variations of chemical concentration or magnetization. The influence of the magnetic field is discussed

  5. Hydrogen absorption and hydrogen-induced phase-separation in amorphous Zr[sub 50]Ni[sub 50-x]Cu[sub x] alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bakonyi, I. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Toth-Kadar, E. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Nagy, I. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Toth, J. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Tompa, K. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Lovas, A. (Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics); Cziraki, A. (Eoetvoes Univ., Budapest (Hungary). Inst. for Solid State Physics); Fogarassay, B. (Eoetvoes Univ., Budapest (Hungary). Inst. for Solid State Physics); Wiesinger, G. (Technische Univ., Vienna (Austria). Inst. fuer Experimentalphysik)

    1994-01-01

    The hydrogen absorption from the gas phase was investigated for melt-quenched Zr[sub 50]Ni[sub 50-x]Cu[sub x] (0[<=]x[<=]25) amorphous alloys by weighing, by thermoelectric power (TEP) and magnetization measurements aand by electron microscopy. A strongly nonmonotonous behaviour been observed, both as a function of the charging time and the Cu-content, for several materials characteristics and also for the nature of the hydrogen-induced phase-separation. (orig.)

  6. Correlation between isothermal expansion and functional properties change of the Fe81B13Si4C2 amorphous alloy

    Directory of Open Access Journals (Sweden)

    Kalezić-Glišović A.

    2009-01-01

    Full Text Available The structural changes effect on functional properties of ribbon shaped samples of the Fe81B13Si4C2 amorphous alloy during annealing process was investigated in this paper. Differential scanning calorimetry method has shown that this alloy crystallizes in one stage, in temperature range from room temperature up to 700°C. Structural relaxation process was investigated by sensitive dilatation method in nonisothermal and isothermal conditions. It has been shown that structural relaxation process occurs in two stages by measuring thermal expansion at constant temperatures of t1=420°C, t2 = 440°C and t3 = 460°C. The first stage is characterized by linear logarithmic dependence of thermal expansion upon time at constant temperature. The second stage of structural relaxation process is characterized by linear dependence of isothermal expansion upon the square root of process time. These results imply that the first stage of structural relaxation process is a rapid kinetic process, while the second stage of structural relaxation process is a slow diffusion process. The rate constants k11 = 2,27⋅10- 3 s-1, k12 = 2,79⋅10-3 s-1, k13 = 3,6⋅10-3 s-1, k21 = 0,67⋅10-4 s-1, k22 = 3,72⋅10-4 s-1, k23 = 21,53⋅10-4 s-1 and activation energies E1 = 48,64 kJ/mol and E2 = 366, 23 kJ/mol were determined for both stages of structural relaxation process. The distinct correlation between structural relaxation process and magnetic susceptibility relative change was determined by thermomagnetic measurements. It has been shown that magnetic susceptibility can be increased by up to 80%, by convenient annealings after structural relaxation process, at magnetic field intensity of 8 kA/m.

  7. EXAFS study of short range order in Fe-Zr amorphous alloys

    International Nuclear Information System (INIS)

    Fernandez-Gubieda, M.L.; Gorria, P.; Barandiaran, J.M.; Barquin, L.F.

    1995-01-01

    Room temperature X-ray absorption spectra on Fe K-edge have been performed in Fe 100-x-y Zr x B y and Fe 86 Zr 7 Cu 1 B 6 alloys (x=7, 7.7, 9; y=0, 2, 4, 6). Fe-Fe coordination number and interatomic distances do not change in any sample. However, small changes in the Fe-Zr short range order, which could explain the evolution of the magnetic properties, have been observed. (orig.)

  8. Constructing superhydrophobic WO3@TiO2 nanoflake surface beyond amorphous alloy against electrochemical corrosion on iron steel

    Science.gov (United States)

    Yu, S. Q.; Ling, Y. H.; Wang, R. G.; Zhang, J.; Qin, F.; Zhang, Z. J.

    2018-04-01

    To eliminate harmful localized corrosion, a new approach by constructing superhydrophobic WO3@TiO2 hierarchical nanoflake surface beyond FeW amorphous alloy formed on stainless steel was proposed. Facile dealloying and liquid deposition was employed at low temperature to form a nanostructured layer composing inner WO3 nanoflakes coated with TiO2 nanoparticles (NPs) layer. After further deposition of PFDS on nanoflakes, the contact angle reached 162° while the corrosion potential showed a negative shift of 230 mV under illumination, resulting in high corrosion resistance in 3.5 wt% NaCl solution. The tradeoff between superhydrophobic surface and photo-electro response was investigated. It was found that this surface feature makes 316 SS be immune to localized corrosion and a pronounced photo-induced process of electron storage/release as well as the stability of the functional layer were detected with or without illumination, and the mechanism behind this may be related to the increase of surface potential due to water repellence and the delayed cathodic protection of semiconducting coating derived mainly from the valence state changes of WO3. This study demonstrates a simple and low-cost electrochemical approach for protection of steel and novel means to produce superhydrophobic surface and cathodic protection with controllable electron storage/release on engineering scale.

  9. Impact of Ion Irradiation upon Structure and Magnetic Properties of NANOPERM-Type Amorphous and Nanocrystalline Alloys

    Directory of Open Access Journals (Sweden)

    Marcel Miglierini

    2015-01-01

    Full Text Available Structural modifications and their impact upon magnetic properties are studied in amorphous and nanocrystalline NANOPERM-type 57Fe75Mo8Cu1B16 alloy. They are introduced by irradiation with 130 keV N+ ions to the total fluencies of up to 2.5 × 1017 ions/cm2 under different cooling conditions. Increased temperature during the irradiation triggers formation of nanocrystallites of bcc-Fe in those subsurface regions that are affected by bombarding ions. No crystallization occurs when good thermal contact between the irradiated sample and a sample holder is assured. Instead, structural rearrangement which favours development of magnetically active regions was determined by the local probe methods of Mössbauer spectrometry. Dipole magnetic interactions dominate in subsurface regions on that side of the ribbons which was exposed to ion irradiation. Nevertheless, structural modifications demonstrate themselves also via macroscopic magnetic parameters such as temperature dependence of magnetization, Curie temperature, and hysteresis loops. Impact of only the temperature itself to the observed effects is assessed by the help of samples that were subjected just to heat treatment, that is, without ion irradiation.

  10. Correlation between structural relaxation enthalpy and superconducting properties of amorphous Zr70Cu30 and Zr70Ni30 alloys

    International Nuclear Information System (INIS)

    Inoue, A.; Matsuzaki, K.; Toyota, N.; Chen, H.S.; Masumoto, T.; Fukase, T.

    1985-01-01

    The anneal-induced change in the superconducting properties together with the irrecoverable relaxation enthalpy (ΔHsub(i,exo)) and recoverable relaxation enthalpy (ΔHsub(r,endo)) of amorphous Zr 70 Cu 30 and Zr 70 Ni 30 alloys was examined. The increase in ΔHsub(i,exo) and the degradation of Tsub(c) progress logarithmically with annealing time tsub(a) in a temperature range of 373 to 523 K. The activation energy and the attempted frequency were respectively estimated to be 1.5 eV and 6.6 x 10 13 sec -1 for the increase in ΔHsub(i,exo) and 1.5 eV and 1.9 x 10 14 sec -1 for the degradation of Tsub(c). The recoverable structure relaxation exerts little effect on Tsub(c). Based on the agreement between the kinetic parameters for the changes of ΔHsub(i,exo) and Tsub(c), it appears that the degradation of Tsub(c) on annealing is associated with the irrecoverable structural relaxation as a result of the annihilation of frozen-in defects and the topological and compositional atomic rearrangement. The values of the attempted frequency being of the order of Debye frequency suggest that the irrecoverable structural relaxation processes occur more or less independently from each other. (author)

  11. Thermal activation analysis of the structural and phase transformations in the Zr-Cu-Nb amorphous alloy

    Directory of Open Access Journals (Sweden)

    Fedotova N.L.

    2011-05-01

    Full Text Available In the present work, the procedure of the estimation of the thermal activation parameters from the data of dilatometric measurements and the results of its application to the Zr-Cu-Nb amorphous alloy discussed. The determination of the thermal activation parameters of the processes occurring in materials under known temperature-force conditions can be useful for the identification of the structural mechanisms of phase transformations and the evolution of defect structure. We used the data of dilatometric measurements for evaluating the effective activation energy. This method exhibits some advantages over the conventional one due to the design features of dilatometers. First, it ensures the precise measurement of strains; second, the assigned temperature regime is very precisely maintained both at the stage of heating and upon isothermal holding; third, it ensures a high-speed continuous record of the experimental data. The developed method of evaluating the effective activation energy from the results of dilatometric experiments provides statistically reliable results. The data of the photometric analysis of structure images are in accordance with the results of dilatometric experiments

  12. Formation of amorphous and nanocrystalline phases in high velocity oxy-fuel thermally sprayed a Fe-Cr-Si-B-Mn alloy

    International Nuclear Information System (INIS)

    Wu Yuping; Lin Pinghua; Xie Guozhi; Hu Junhua; Cao Ming

    2006-01-01

    High velocity oxy-fuel (HVOF) thermal spray was used to deposit a Fe-Cr-Si-B alloy coating onto stainless steel (1Cr18Ni9Ti) substrate. Microstructures of the powder and the coating were investigated by X-ray diffraction (XRD), scanning election microscopy (SEM), transmission election microscopy (TEM) and differential scanning calorimeter (DSC). The coating had layered morphologies due to the deposition and solidification of successive molten or half-molten splats. The microstructures of the coating consisted of a Fe-Cr-rich matrix and several kinds of borides. The Fe-Cr-rich matrix contained both amorphous phase and nanocrystalline grains with a size of 10-50 nm. The crystallization temperature of the amorphous phase was about 605 deg. C. The formation of the amorphous phase was attributed to the high cooling rates of molten droplets and the proper powder compositions by effective addition of Cr, Mn, Si and B. The nanocrystalline grains could result from crystallization in amorphous region or interface of the amorphous phase and borides by homogeneous and heterogeneous nucleation

  13. Investigation into the Origin of Magnetic Properties of Amorphous Metallic Alloys.

    Science.gov (United States)

    1981-10-01

    gratefully acknowledged. References Alben R C, Budnick J I and ( argill i S III 1976 Merallt (lasseN ed H J Leamy and J Gilman (Metals [Park, Ohio: American...cast annealed Q 20 as 4nMs Os 4nM5 Alloy System emu/8 kG emu/g kG Reference 0. 5 l-e-B 180 16.7 184 17.0 1II 46,.( le -B-C 180 16.9 184 17.3 [21, (4] 25...Dans les alliages pour paliers au phosphore, le phosphore segrege au cours du recuit, cc qui conduit i une fragilisation de l’echantillon. Dans cet

  14. Amorphization by friction welding between 5052 aluminum alloy and 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, S.; Tsubakino, H.; Okita, K.; Aritoshi, M.; Tomita, T.

    2000-04-14

    The joining of dissimilar metals such as aluminum/stainless steel is a very important technique. In the case of fusion welding of an Fe-Al system, excess formation of brittle intermetallic compounds degrades the joint. Since friction welding is one of the solid-state bonding procedures, few intermetallic compounds are formed at the weld interface. However, in the Al-Fe system, the solid solubility is almost nil, so some intermetallic compounds will be formed in spite of the friction welding. In the present study, microstructure of the friction weld interface between Al-Mg alloy and austenitic stainless steel was investigated by high resolution transmission electron microscopy and the mechanism of friction welding was examined.

  15. PHB, crystalline and amorphous magnesium alloys: Promising candidates for bioresorbable osteosynthesis implants?

    Energy Technology Data Exchange (ETDEWEB)

    Celarek, Anna [Institute for Building Construction and Technology E-206-4, Vienna University of Technology, Karlsplatz 13, 1040 Vienna (Austria); Kraus, Tanja [Department of Paediatric Orthopaedics, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz (Austria); Tschegg, Elmar K., E-mail: elmar.tschegg@tuwien.ac.at [Institute for Building Construction and Technology E-206-4, Vienna University of Technology, Karlsplatz 13, 1040 Vienna (Austria); Fischerauer, Stefan F. [Department of Paediatric and Adolescent Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz (Austria); Stanzl-Tschegg, Stefanie [Department of Material Sciences and Process Engineering, Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Str. 82, 1190 Vienna (Austria); Uggowitzer, Peter J. [Department of Materials, Laboratory for Metal Physics and Technology, ETH Zurich, 8093 Zurich (Switzerland); Weinberg, Annelie M. [Department of Paediatric and Adolescent Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz (Austria)

    2012-08-01

    In this study various biodegradable materials were tested for their suitability for use in osteosynthesis implants, in particular as elastically stable intramedullary nails for fracture treatment in paediatric orthopaedics. The materials investigated comprise polyhydroxybutyrate (PHB), which belongs to the polyester family and is produced by microorganisms, with additions of ZrO{sub 2} and a bone graft substitute; two crystalline magnesium alloys with significantly different degradation rates ZX50 (MgZnCa, fast) and WZ21 (MgYZnCa, slow); and MgZnCa bulk metallic glasses (BMG). Push-out tests were conducted after various implantation times in rat femur meta-diaphysis to evaluate the shear forces between the implant material and the bone. The most promising materials are WZ21 and BMG, which exhibit high shear forces and push-out energies. The degradation rate of ZX50 is too fast and thus the alloy does not maintain its mechanical stability long enough during the fracture-healing period. PHB exhibits insufficient mechanical properties: it degrades very slowly and the respective low shear forces and push-out energy levels are unsatisfactory. - Highlights: Black-Right-Pointing-Pointer In-vivo (rat model) investigation of biodegradable materials suitable for ESIN. Black-Right-Pointing-Pointer Materials: polymer PHB, crystalline Mg ZX50 and Mg WZ21, MgZnCa bulk metallic glasses. Black-Right-Pointing-Pointer Evaluated interface shear strength, push-out energies, stiffness, histology. Black-Right-Pointing-Pointer Mg WZ21 suitable, other materials only after alterations.

  16. Structural and thermal investigations of an amorphous GaSe{sub 9} alloy using EXAFS, cumulant expansion, and reverse Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, M. C.; Maia, R. N. A.; Araujo, R. M. T.; Machado, K. D., E-mail: kleber@fisica.ufpr.br [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Stolf, S. F. [Centro de Engenharia e Ciências Exatas, UNIOESTE, 85903-000 Toledo, Paraná (Brazil)

    2015-02-07

    In this article, we investigated structural and thermal properties of an amorphous alloy of the Ga–Se system. The amorphous GaSe{sub 9} alloy was produced by mechanical alloying and it was studied using EXAFS spectroscopy and cumulant expansion method. We also made reverse Monte Carlo simulations using the total structure factor S(K) obtained from x-ray diffraction and the EXAFS χ(k) oscillations on Se and Ga K edges as input data. Several parameters, such as average coordination numbers and interatomic distances, structural and thermal disorders, asymmetry of the partial distribution functions g{sub ij}(r), and Einstein and Debye temperatures, were determined. The g{sub ij}{sup E}(r) functions were reconstructed from the cumulants C{sub 1}, C{sub 2}, and C{sub 3} obtained from the Einstein model, and they were compared to the g{sub ij}{sup RMC}(r) functions obtained from the simulations. The simulations also furnished the partial bond angle distribution functions Θ{sub ijℓ}(cosθ), which describe the angular distribution of bonds between first neighbors, and give information about the kind of structural units present in the alloy.

  17. Structure Analyses of Fe-based Metallic Glasses by Electron Diffraction

    Directory of Open Access Journals (Sweden)

    Akihiko Hirata

    2010-12-01

    Full Text Available Nanoscale structural information of amorphous structures has become obtainable by using nanobeam electron diffraction in combination with high resolution imaging. In addition, accurate radial distribution function analysis using energy filter has also become available to know averaged amorphous structures. In this paper, we introduce some applications of these techniques, especially to several Fe-based metallic glasses. On the basis of these results, we discuss a relationship between the glass structure and the glass stability in Fe-based metallic glasses

  18. Development of solid-state joining technology of dissimilar metals using amorphous metastable alloy powders

    International Nuclear Information System (INIS)

    Lee, Min Ku; Rhee, Chang Kyu; Uhm, Young Rang; Park, Jin Ju; Lee, Jeong Gu; Kim, Gwang Ho; Hong, Sung Mo; Lee, Jong Geuk; Kim, Kyoung Ho

    2007-04-01

    Many nuclear components such as nozzles, steam generator, pipes, condensers, and heat exchangers require a realization of the reliable and high-performance joining or welding between the dissimilar metals or alloys, despite the fact that their melting points, thermal expansion coefficients and physical properties are quite different from each other. The conventional arc welding processes (SMAW, TIG), however, which is currently used as a welding process for NPP components, have not met the requirements of obtaining a reliable and high-quality dissimilar joints, as demonstrated from a number of the previously reported accidents or material failures in the welded joints. This originates from the various weaknesses of the arc welding processes (more than 1700 .deg. C) such as high residual stresses which is sensitive to SCC, porous or deformed joint structures, a formation of grain-coarsened HAZ and an induced degradation of the base metals in the vicinity of the joint. Moreover, they are not applicable to a joining of the dissimilar metals when their melting point or mechanical/physical properties are quite different. In this research, the low-temperature joining (700 .deg. C - 800 .deg. C) and simultaneously strong diffusion bonding technologies between the dissimilar Ti and Cu metals have been developed for the applications to the dissimilar joints of various nuclear tube components

  19. Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} (R=Sm, Gd, Ho) alloys in liquid and amorphous states

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation); Svec, P.; Svec, P.; Janickovic, D. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Sidorova, E. [Plekhanov Russian University of Economics, Moscow (Russian Federation); Son, L. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation)

    2016-06-15

    Electrical resistivity and magnetic susceptibility of Al{sub 86}Ni{sub 8}Sm{sub 6}, Al{sub 86}Ni{sub 8}Gd{sub 6} and Al{sub 86}Ni{sub 8}Ho{sub 6} alloys are studied in a wide temperature range including amorphous, crystalline and liquid states. The negative value of resistivity temperature coefficient in amorphous ribbons is explained by the structural separation starting much before the beginning of their crystallization. The effective magnetic moments per Gd and Ho atoms are found to be essentially lower than for R{sup 3+} ions. The results are discussed in supposition of directed bonds between rare earth and aluminum atoms. - Highlights: • Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} alloys are studied experimentally. • The negative value of rtc in amorphous ribbons is explained. • The effective magnetic moments per Gd and Ho are found to be lower than for R{sup 3+} ions.

  20. Applications Ni59Nb40Pt(1-x) Xx (X= Sn,Sby and Ru) amorphous alloy as anodes for direct methanol (DMFC) fuel cells

    International Nuclear Information System (INIS)

    Rodriguez Pierna, A

    2005-01-01

    The search of new anode materials of amorphous nature for methanol fuel cells is one of the aims of this work.The main problem that fuel cells present is related to the catalytic material and its distribution in a suitable matrix.Amorphous alloys are particularly attractive materials as catalyst supports because of their high conductivity, high corrosion resistance in sulphuric acid, as well as the possibility of a good distribution of the electrocatalytic particles, mainly platinum and platinum-tin, on a conducting matrix.The electrooxidation of methanol, in percloric acid medium, has been used as probe to evaluate the performance of metallic amorphous electrodes, with compositions Ni 5 9Nb 4 0Pt 1 , Ni 5 9Nb 4 0Pt 0 .6Sn0.4, Ni 5 9Nb 4 0Pt 0 .6Sb 0 .4 and Ni 5 9Nb 4 0Pt 0 .6Ru 0 .4.The electrocatalytic activity of the alloyed ribbons of compositions (x = 0.6, 1% at. in platinum) is improved considerably, so much for the change in their composition, as for the roughness degree that the catalytic surfaces present. The increase of the tolerance to adsorbed species, and better resistance to the poisoning of their catalytic centers, can be observed by means of voltammetric experiments at different activation times with HF 48%. The electrooxidation of methanol in the amorphous alloy of composition Ni 5 9Nb 4 0Pt 1 , is influenced by the nature of the used electrolyte, presenting smaller values of current density in solutions 1M H 2 SO 4 than in 1M of HClO 4 .This behavior is not observed in the alloy Ni 5 9Nb 4 0Pt 0 .6Sn 0 .4, Ni 5 9Nb 4 0Pt 0 .6Sb 0 .4 and Ni 5 9Nb 4 0Pt 0 .6Ru 0 .4which does not present a poisoning of the catalytic centers depending on the used electrolyte.Adding tin to the alloys showed the existence of a synergetic effect in the methanol electrooxidation process, attaining to a descent of 20 mV vs Ag/AgCl in the onset potential, and about 200 mV in the maximun peak potential

  1. Effect of amorphous Mg{sub 50}Ni{sub 50} on hydriding and dehydriding behavior of Mg{sub 2}Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D., E-mail: danny.guzman@uda.cl [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapo (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Fernandez, J.F.; Sanchez, C. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Av. Los Carrera 01567, Quilpue, Pontificia Universidad Catolica de Valparaiso, PUCV (Chile); Aguilar, C. [Departamento de Ingenieria Metalurgica y Materiales, Universidad Tecnica Federico Santa Maria, Av. Espana 1680, Valparaiso (Chile); Tapia, P. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile)

    2011-04-15

    Composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50} was prepared by mechanical milling starting with nanocrystalline Mg{sub 2}Ni and amorphous Mg{sub 50}Ni{sub 50} powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg{sub 50}Ni{sub 50} improved the hydriding and dehydriding kinetics of Mg{sub 2}Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: {yields} First study of the hydriding behavior of composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50}. {yields} Microstructural characterization of composite material using XRD and SEM was obtained. {yields} An improved effect of Mg{sub 50}Ni{sub 50} on the Mg{sub 2}Ni hydriding behavior was verified. {yields} The apparent activation energy for the hydrogen desorption of composite was obtained.

  2. Study on glass-forming ability and hydrogen storage properties of amorphous Mg60Ni30La10−xCox (x = 0, 4) alloys

    International Nuclear Information System (INIS)

    Lv, Peng; Wang, Zhong-min; Zhang, Huai-gang; Balogun, Muhammad-Sadeeq; Ji, Zi-jun; Deng, Jian-qiu; Zhou, Huai-ying

    2013-01-01

    Mg 60 Ni 30 La 10−x Co x (x = 0, 4) amorphous alloys were prepared by rapid solidification, using a melt-spinning technique. X-ray diffraction and differential scanning calorimetry analysis were employed to measure their microstructure, thermal stability and glass-forming ability, and hydrogen storage properties were studied by means of PCTPro2000. Based on differential scanning calorimetry results, their glass-forming ability and thermal stability were investigated by Kissinger method, Lasocka curves and atomic cluster model, respectively. The results indicate that glass-forming ability, thermal properties and hydrogen storage properties in the Mg-rich corner of Mg–Ni–La–Co system alloys were enhanced by Co substitution for La. It can be found that the smaller activation energy (ΔΕ) and frequency factor (υ 0 ), the bigger value of B (glass transition point in Lasocka curves), and higher glass-forming ability of Mg–Ni–La–Co alloys would be followed. In addition, atomic structure parameter (λ), deduced from atomic cluster model is valuable in the design of Mg–Ni–La–Co system alloys with good glass-forming ability. With an increase of Co content from 0 to 4, the hydrogen desorption capacity within 4000 s rises from 2.25 to 2.85 wt.% at 573 K. - Highlights: • Amorphous Mg 60 Ni 30 La 10−x Co x (x = 0 and 4) alloys were produced by melt spinning. • The GFA and hydrogen storage properties were enhanced by Co substitution for La. • With an increase of Co content, the hydrogen desorption capacity rises at 573 K

  3. Superconductivity, magnetic susceptibility, and electronic properties of amorphous (Mo/sub 1-x/Ru/sub x/)80P20 alloys obtained by liquid quenching

    International Nuclear Information System (INIS)

    Johnson, W.L.; Poon, S.J.; Duwez, P.

    1977-11-01

    Results of x-ray diffraction, transmission electron diffraction, and crystallization studies on amorphous (Mo/sub 1-x/Ru/sub x/) 80 P 20 alloys obtained by liquid quenching are presented and discussed. The alloys are all found to be superconducting with transition temperatures ranging from approximately 3 0 K to approximately 9 0 K. The variation of T/sub c/ with alloy composition is compared to that obtained by Collver and Hammond for vapor quenched transition metal films. Results of magnetic susceptibility measurements are used to estimate the variation of the electronic density of states at the Fermi level, N(0), from the Pauli paramagnetic contribution. The relationship between the variation of T/sub c/ and N(0) is discussed in terms of the microscope theory of superconductivity. Finally, results of measurements of the upper critical field H/sub c2/, and the normal state electronic transport properties are presented and compared with recent theoretical models for amorphous superconductors

  4. 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.

  5. Effects of ion-implanted C on the microstructure and surface mechanical properties of Fe alloys implanted with Ti

    International Nuclear Information System (INIS)

    Follstaedt, D.M.; Knapp, J.A.; Pope, L.E.; Yost, F.G.; Picraux, S.T.

    1984-01-01

    The microstructural and tribological effects of ion implanting C into Ti-implanted, Fe-based alloys are examined and compared to the influence of C introduced by vacuum carburization during Ti implantation alone. The amorphous surface alloy formed by Ti implantation of pure Fe increases in thickness when additional C is implanted at depths containing Ti but beyond the range of carburization. Pin-on-disc tests of 15-5 PH stainless steel show that implantation of both Ti and C reduces friction significantly under conditions where no reduction is obtained by Ti implantation alone; wear depths are also less when C is implanted. All available experimental results can be accounted for by consideration of the thickness and Ti concentration of the amorphous Fe-Ti-C alloy. The thicker amorphous layer on samples implanted with additional C extends tribological benefits to more severe wear regimes

  6. Design and Characterisation of Metallic Glassy Alloys of High Neutron Shielding Capability

    Science.gov (United States)

    Khong, J. C.; Daisenberger, D.; Burca, G.; Kockelmann, W.; Tremsin, A. S.; Mi, J.

    2016-01-01

    This paper reports the design, making and characterisation of a series of Fe-based bulk metallic glass alloys with the aim of achieving the combined properties of high neutron absorption capability and sufficient glass forming ability. Synchrotron X-ray diffraction and pair distribution function methods were used to characterise the crystalline or amorphous states of the samples. Neutron transmission and macroscopic attenuation coefficients of the designed alloys were measured using energy resolved neutron imaging method and the very recently developed microchannel plate detector. The study found that the newly designed alloy (Fe48Cr15Mo14C15B6Gd2 with a glass forming ability of Ø5.8 mm) has the highest neutron absorption capability among all Fe-based bulk metallic glasses so far reported. It is a promising material for neutron shielding applications. PMID:27848991

  7. Potentiodynamic polarization studies of bulk amorphous alloy Zr57Cu15.4Ni12.6Al10Nb5 and Zr59Cu20Ni8Al10Ti3 in aqueous HNO3 media

    International Nuclear Information System (INIS)

    Sharma, Poonam; Dhawan, Anil; Jayraj, J.; Kamachi Mudali, U.

    2013-01-01

    The potentiodynamic polarization studies were carried out on Zr based bulk amorphous alloy Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 in solutions of 1 M, 6 M and 11.5 M HNO 3 aqueous media at room temperature. As received specimens of Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 (5 mm diameter rod) and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 (3 mm diameter rod) were polished with SiC paper before testing them for potentiodynamic polarization studies. The amorphous nature of the specimens was checked by X-ray diffraction. The bulk amorphous alloy Zr 59 Cu 20 Ni 8 Al 10 Ti 3 shows the better corrosion resistance than Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy in the aqueous HNO 3 media as the value of the corrosion current density (I corr ) for Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy were found to be more than Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy in aqueous HNO 3 media. The improved corrosion resistance of Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy is possibly due to the presence of Ti and formation of TiO 2 during anodic oxidation. Both Zr based bulk amorphous alloys shows wider passive range at lower concentration of nitric acid and the passive region gets narrowed down with the increase in concentration. A comparison of data obtained from both the Zr-based bulk amorphous alloys is made and results are discussed in the paper. (author)

  8. Crystallization kinetics of Fe-B based amorphous alloys studied in-situ using X-rays diffraction and differential scanning calorimetry

    Directory of Open Access Journals (Sweden)

    Santos D.R. dos

    2001-01-01

    Full Text Available The crystallization processes for the amorphous metallic alloys Fe74B17Si2Ni4Mo3 and Fe86B6Zr7Cu1 (at. % were investigated using X-rays diffraction measurements performed in-situ during Joule-heating, with simultaneous monitoring of the electrical resistance. We determined the main structural transitions and crystalline phases formed during heating, and correlated these results to the observed resistance variations. As the annealing current is increased, the resistance shows an initial decrease due to stress relaxation, followed by a drop to a minimum value due to massive nucleation and growth of alpha-Fe nanocrystals. Further annealing causes the formation of small fractions of Fe-B, B2Zr or ZrO2, while the resistance increases due to temperature enhancement. In situ XRD measurements allowed the identification of metastable phases, as the gamma-Fe phase which occurs at high temperatures. The exothermal peaks observed in the differential scanning calorimetry (DSC for each alloy corroborate the results. We also have performed DSC measurements with several heating rates, which allowed the determination of the Avrami exponent and crystallization activation energy for each alloy. The obtained activation energies (362 and 301 kJ/mol for Fe-B-Zr-Cu; 323 kJ/mol for Fe-B-Si-Ni-Mo are comparable to reported values for amorphous iron alloys, while the Avrami exponent values (n = 1.0 or n = 1.2 are consistent with diffusion controlled crystallization processes with nucleation rates close to zero.

  9. Structural and electronic properties of binary amorphous aluminum alloys with transition metals and rare earth metals; Strukturelle und elektronische Eigenschaften binaerer amorpher Aluminiumlegierungen mit Uebergangsmetallen und Metallen der Seltenen Erden

    Energy Technology Data Exchange (ETDEWEB)

    Stiehler, Martin

    2012-02-03

    The influence of the d-states of the transition metals on the structure formation in amorphous alloys has so far only been inadequately understood. The present work aims to elaborate additional contributions to the understanding of binary amorphous aluminum alloys with transition metals. Special emphasis was placed on alloys with a subgroup of the transition metals, the rare earth metals. Within the scope of the present work, layers of Al-Ce in the region of 15at% Ce-80at% Ce were produced by sequential flash evaporation at 4.2K in the high vacuum, and characterized electronically by electrical resistance and Hall effect measurements as well as structurally by transmission electron diffraction. In addition, studies of plasma resonance were carried out by means of electron energy loss spectroscopy. In the range of 25at% Ce-60at% Ce, homogeneous amorphous samples were obtained. Especially the structural investigations were made difficult by oxidation of the material. The influence of the Ce-4f electrons manifests itself mainly in the low-temperature and magnetoresistance, both of which are dominated by the Kondo effect. The Hall effect in Al-Ce is dominated by anomalous components over the entire temperature range (2K-320K), which are attributed to skew-scattering effects, also due to Ce-4f electrons. Down to 2K there was no macroscopic magnetic order. In the region 2K-20K, the existence of clusters of ordered magnetic moments is concluded. For T> 20K, paramagnetic behavior occurs. With regard to the structural and electronic properties, a-Al-Ce can be classified as a group with a-Al- (Sc, Y, La). In the sense of plasma resonance, a-Al-Ce is excellently arranged in a system known from other Al transition metal alloys. Furthermore, by increasing the results of binary amorphous Al transition metal alloys from the literature, it has been found that the structure formation in these systems is closely linked to a known but still unexplained structure-forming effect that

  10. High-Efficiency Amorphous Silicon Alloy Based Solar Cells and Modules; Final Technical Progress Report, 30 May 2002--31 May 2005

    Energy Technology Data Exchange (ETDEWEB)

    Guha, S.; Yang, J.

    2005-10-01

    The principal objective of this R&D program is to expand, enhance, and accelerate knowledge and capabilities for development of high-efficiency hydrogenated amorphous silicon (a-Si:H) and amorphous silicon-germanium alloy (a-SiGe:H) related thin-film multijunction solar cells and modules with low manufacturing cost and high reliability. Our strategy has been to use the spectrum-splitting triple-junction structure, a-Si:H/a-SiGe:H/a-SiGe:H, to improve solar cell and module efficiency, stability, and throughput of production. The methodology used to achieve the objectives included: (1) explore the highest stable efficiency using the triple-junction structure deposited using RF glow discharge at a low rate, (2) fabricate the devices at a high deposition rate for high throughput and low cost, and (3) develop an optimized recipe using the R&D batch large-area reactor to help the design and optimization of the roll-to-roll production machines. For short-term goals, we have worked on the improvement of a-Si:H and a-SiGe:H alloy solar cells. a-Si:H and a-SiGe:H are the foundation of current a-Si:H based thin-film photovoltaic technology. Any improvement in cell efficiency, throughput, and cost reduction will immediately improve operation efficiency of our manufacturing plant, allowing us to further expand our production capacity.

  11. The Effect of Crystallizing Heat Treatments on the Corrosion and Abrasive Wear Behaviours of Amorphous Fe40Ni40B20 Alloy

    International Nuclear Information System (INIS)

    Kim, Jong Sang; Kang, In Won; Pyun, Su Il

    1988-01-01

    The corrosion and abrasive wear characteristics of Fe 40 Ni 40 B 20 metallic glass have been studied as a function of crystallizing heat treatment by using both immersion test and potentiodynamic polarization techniques in 1 N H 2 SO 4 solution at 30 .deg. C, and also pin-on-disc type abrasive wear test method. The degree of crystallization was realized by means of X-ray diffraction before and after crystallizing heat treatment. it has been found that the crystallized state, annealed state, and amorphous state specimens increase in corrosion and abrasive wear resistances in that order. More Ni 2 + ions in the crystallized state are dissolved in the test solution as compared with those in the amorphous state. The amorphous state alloy Fe 40 Ni 40 B 20 exhibits much higher abrasive wear losses than conventional crystalline materials such as steels. The changes of corrosion and abrasive wear resistance by crystallization are discussed in terms of the heterogeneity in materials and the transition of the abrasive wear mechanism caused due to the precipitation of Ni 3 B particles resulting during crystallizing heat treatment

  12. Bulk nanocrystalline Al85Ni10La5 alloy fabricated by spark plasma sintering of atomized amorphous powders

    International Nuclear Information System (INIS)

    Sasaki, T.T.; Hono, K.; Vierke, J.; Wollgarten, M.; Banhart, J.

    2008-01-01

    Amorphous Al 85 Ni 10 La 5 powders were consolidated to cylindrical samples by spark plasma sintering (SPS), and their microstructures and mechanical properties were investigated. When the powders were consolidated below the crystallization temperature, an amorphous phase was retained in the consolidated sample. Sintering above the crystallization temperature caused full crystallization. The Vickers hardness of the amorphous-containing sample was about 350 HV in the as-sintered state and increased up to 450 HV by a subsequent heat treatment just below the crystallization temperature. The highest hardness was achieved in a nanocrystalline microstructure. Compression tests revealed the brittle nature of the consolidated samples although the fracture and yield strength was higher than 1 GPa. The brittleness is due to the low relative density of the amorphous-containing samples and the presence of a large amount of intermetallic compounds in the fully crystallized sample

  13. Glass forming ability and mechanical properties of the NiZrTiSi amorphous alloys modified with Al, Cu and Nb additions

    International Nuclear Information System (INIS)

    Czeppe, Tomasz; Ochin, Patrick; Sypien, Anna

    2007-01-01

    The composition of the amorphous alloy Ni 59 Zr 20 Ti 16 Si 5 was modified with 2-9 at.% additions of Cu, Al and Nb. The ribbons and the bars 2.7 mm in diameter were prepared by melt spinning and injection casting from the alloys of the compositions: Ni 56 Zr 18 Ti 16 Si 5 Al 3 Cu 2 , Ni 56 Zr 18 Ti 13 Al 6 Si 5 Cu 2 , Ni 56 Zr 16 Ti 12 Nb 9 Al 3 Cu 2 Si 2 and Ni 56 Zr 16 Ti 12 Nb 6 Al 6 Cu 2 Si 2 . All ribbons were amorphous up to the resolution of the X-ray diffraction and conventional transmission electron microscopy, however rods were partially crystalline. Increase of Al content lowered and Nb content slightly increased crystallization start temperature T x and glass transition temperature T g . The influence of composition changes on the overcooled liquid range ΔT was more complicated. The increase of Nb and decrease of Ti and Zr content led to the remarkable increase of the liquidus temperature T l . As a result GFA calculated as T g /T l was lowered to the values about 0.63 for 6 and 9 at.% Nb addition. The activation energies for primary crystallization in alloy with 6 at.% Al and 6 at.% of Nb, were determined. The changes of tensile test strength and microhardness with Al and Nb additions showed hardening effect caused by Nb additions and increase in fracture strength with increasing Al content

  14. Development of Fe-based bulk metallic glasses as potential biomaterials.

    Science.gov (United States)

    Li, Shidan; Wei, Qin; Li, Qiang; Jiang, Bingliang; Chen, You; Sun, Yanfei

    2015-01-01

    A new series of Fe80-x-yCrxMoyP13C7 (x = 10, y = 10; x = 20, y = 5; x = 2 0, y = 10, all in at.%) bulk metallic glasses (BMGs) with the maximum diameter of 6mm have been developed for biomedical implant application by the combination method of fluxing treatment and J-quenching technique. The corrosion performance of the present Fe-based BMGs is investigated in both Hank's solution (pH = 7.4) and artificial saliva solution (pH = 6.3) at 37 °C by electrochemical measurements. The result indicates that the corrosion resistance of the present Fe-based BMGs in the above two simulated body solutions is much better than that of biomedical 316 L stainless steel (316 L SS), and approaching that of Ti6Al4V biomedical alloy (TC4). The concentrations of Fe, Ni and Cr ions released into the Hank's solution and artificial saliva solution from the present Fe-based BMGs after potentiodynamic polarization are significant lower than that released from 316 L SS. The biocompatibility of the present Fe-based BMGs is evaluated through the in vitro test of NIH3T3 cells culture in the present Fe-based BMG extraction media for 1, 3 and 5 days. The result indicates that the present Fe-based BMGs exhibit no cytotoxicity to NIH3T3 cells. And the test result of the cell adhesion and growth on the surface of the samples indicates that the present Fe-based BMGs exhibit the better cell viability compared with 316 L SS and TC4 biomedical alloys. The present Fe-based BMGs, especially Fe55Cr20Mo5P13C7 BMG, exhibit good glass formation ability, the high corrosion resistance and excellent biocompatibility, suggesting their promising potential as biomaterials. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness; Tratamiento termico de la aleacion amorfa base Fe 2605SA1, analisis de sus defectos y microdureza

    Energy Technology Data Exchange (ETDEWEB)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. El Cerillo Piedras Blancas, 50000 Toluca, Estado de Mexico (Mexico)

    2007-07-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  16. Influence of structural transformations on functional properties of Fe75Ni2Si8B13C2 amorphous alloy

    Czech Academy of Sciences Publication Activity Database

    Minić, Dušan M.; Blagojević, V.; Maričić, A.; Žák, Tomáš; Minić, Dragica M.

    2012-01-01

    Roč. 134, č. 1 (2012), s. 111-115 ISSN 0254-0584 R&D Projects: GA MŠk 1M0512 Institutional support: RVO:68081723 Keywords : Amorphous materials * Mössbauer spectroscopy * Electrical properties * Magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.072, year: 2012

  17. Field-induced non-collinear magnetic structures in amorphous Co{sub 80-x}Dy {sub x}B{sub 20} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Annouar, F. [Laboratoire de Physique des Materiaux et de Micro-electronique, Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366, Route d' El Jadida, km-8, Casablanca (Morocco)]. E-mail: annouarfouad@yahoo.fr; Roky, K. [Faculte des Sciences et Technique de Tanger, Departement de Physique (Morocco); Faculte des Sciences de Tetouan, Departement de Physique (Morocco); Lassri, H. [Laboratoire de Physique des Materiaux et de Micro-electronique, Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366, Route d' El Jadida, km-8, Casablanca (Morocco); Elmoussaoui, A. [Faculte des Sciences de Tetouan, Departement de Physique (Morocco); Driouch, L. [Laboratoire de Physique des Materiaux et de Micro-electronique, Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366, Route d' El Jadida, km-8, Casablanca (Morocco); Ayadi, M. [Laboratoire de Physique des Materiaux et de Micro-electronique, Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366, Route d' El Jadida, km-8, Casablanca (Morocco); Omri, M. [Laboratoire de Physique des Materiaux et de Micro-electronique, Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366, Route d' El Jadida, km-8, Casablanca (Morocco); Krishnan, R. [Laboratoire de Magnetisme et d' Optique de l' Universite de Versailles, Ba-hat timent Fermat, 45 Avenue des Etats-Unis 78035 Versailles cedex (France)

    2005-07-25

    Amorphous Co{sub 80-x}Dy {sub x}B{sub 20} alloys have been prepared by melt spinning technique and their magnetic properties have been studied. The mean field theory has been used to explain the temperature dependence of the magnetization. High-field magnetization studies performed at 4.2 K in magnetic fields up to 38 T have revealed, for samples with stoichiometry close to that of a compensated ferrimagnet, a magnetic behavior that is characteristic of a non-collinear magnetic structure of the Dy and Co sublattices. From the non-collinear regime the exchange interactions between the Co and Dy magnetic sublattices and the magnetic anisotropy constants have been evaluated.

  18. Influence of Microstructure on Microhardness of Fe81Si4B13C2 Amorphous Alloy after Thermal Treatment

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica, M.; Blagojević, V.; Minić, Dušan M.; Gavrilović, A.; Rafailović, L.; Žák, Tomáš

    42A, č. 13 (2011), s. 4106-4112 ISSN 1073-5623 R&D Projects: GA MŠk(CZ) 1M0512 Institutional research plan: CEZ:AV0Z2041904 Keywords : bulk metallic-glass * mechanical properties * Fe81B13SI4C2 alloy * B alloys * alpha-Fe * crystallization * phase * nanocrystallization * behavior Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.545, year: 2011

  19. Determination of properties of high temperature superconductors and amorphous metallic alloys using positron annihilation techniques. Final report for the period 15 January 1992 - 15 July 1995

    International Nuclear Information System (INIS)

    Kristiak, J.

    1995-11-01

    The positron lifetime results obtained on amorphous thermally treated Ni 25 Zr 55 Al 20 alloy indicate that positrons annihilate at places with different properties. The observed shifts of positron lifetime distribution were analyzed in the terms of a relaxation of free-volume, i.e. chemical (CSRO) and topological (TSRO) short range ordering. The upper limit of the activation energy of CSRO and TSRO relaxation was determined to be 2.2eV and 2.6eV, respectively. Positron lifetime τ and Doppler broadening of the annihilation line measurements on very pure C 60 sample as a function of temperature between 120 and 300 K have been reported. A rapid change of τ was observed between 240 and 250 K. This results indicate that the lattice from C 60 molecules is undergoing a phase transition and the phases coexist over an ∼ 10K range. The annihilation of positrons in amorphous tetramethylpoly-carbonate has been investigated in the temperature range from 30 to 300 K. The observed dependences of the mean lifetime of oPs and its relative intensity 1 on temperature were interpreted within the framework of the microstructural free-volume concept. The man radius of free space (hole) was deduced to be around 3,1.10 -10 m. Refs, figs, tabs

  20. The Effects of Strain-Annealing on Tuning Permeability and Lowering Losses in Fe-Ni-Based Metal Amorphous Nanocomposites

    Science.gov (United States)

    Aronhime, Natan; DeGeorge, Vincent; Keylin, Vladimir; Ohodnicki, Paul; McHenry, Michael E.

    2017-11-01

    Fe-Ni-based metal amorphous nanocomposites with a range of compositions (Fe100- x Ni x )80Nb4Si2B14 (30 ≤ x ≤ 70) are investigated for motor and transformer applications, where it is beneficial to have tunable permeability. It is shown that strain annealing offers an effective method for tuning permeability in these alloys. For an Fe-rich alloy, permeability increased from 4000 to 16,000 with a positive magnetostriction. In a Ni-rich alloy, permeability decreased from 290 to 40 with a negative magnetostriction. Significant elongations (above 60%) are observed during strain annealing at high stress. Crystallization products have been determined in all alloys heated to 480°C. γ-FeNi is formed in all alloys, while (Fe30Ni70)80Nb4Si2B14 also undergoes secondary crystallization at temperatures of approximately 480°C to form a phase with the Cr23C6-type structure and a likely composition of Fe21Nb2B6. Toroidal losses have been measured for (Fe70Ni30)80Nb4Si y B16- y (0 ≤ y ≤ 3) at various annealing temperatures. At an induction of 1 T and frequency of 400 Hz and 1 kHz, the toroidal losses obtained are W1.0T, 400 Hz = 0.9 W/kg and W1.0T, 1 kHz = 2.3 W/kg, respectively. These losses are lower than losses recently reported for state of the art 3.0% and 6.5% silicon steels, a Metglas Fe-based amorphous alloy, and some Fe-based nanocomposites.

  1. Effect of an amorphous titania nanotubes coating on the fatigue and corrosion behaviors of the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys.

    Science.gov (United States)

    Campanelli, Leonardo Contri; Bortolan, Carolina Catanio; da Silva, Paulo Sergio Carvalho Pereira; Bolfarini, Claudemiro; Oliveira, Nilson Tadeu Camarinho

    2017-01-01

    An array of self-organized TiO 2 nanotubes with an amorphous structure was produced on the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys, and the resulting fatigue and corrosion behaviors were studied. The electrochemical response of the nanotubular oxide surfaces was investigated in Ringer physiological solution through potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The absence of transpassivation in the chloride-containing solution, in addition to the micron-scale values of the passivation current density, indicated the excellent corrosion behavior of the coating and the satisfactory protection against the creation of potential stress concentrators in the surface. Axial fatigue tests were performed in physiological solution on polished and coated conditions, with characterization of the treated surfaces by scanning electron microscopy before and after the tests. The surface modification was not deleterious to the fatigue response of both alloys mainly due to the nano-scale dimension of the nanotubes layer. An estimation based on fracture mechanics revealed that a circumferential crack in the range of 5μm depth would be necessary to affect the fatigue performance, which is far from the thickness of the studied coating, although no cracks were actually observed in the oxide surfaces after the tests. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. An investigation of optimal interfacial film condition for Cu-Mn alloy based source/drain electrodes in hydrogenated amorphous silicon thin film transistors

    Directory of Open Access Journals (Sweden)

    Haruhiko Asanuma

    2012-06-01

    Full Text Available To aid in developing next generation Cu-Mn alloy based source/drain interconnects for thin film transistor liquid crystal displays (TFT-LCDs, we have investigated the optimal structure of a pre-formed oxide layer on phosphorus doped hydrogenated amorphous silicon (n+a-Si:H that does not degrade TFT electrical properties. We use transmission electron microscopy (TEM and electron energy loss spectroscopy (EELS to examine composition depth profiles of and structural information for the Cu-Mn alloy/n+a-Si:H interface region. In aiming to achieve the same electrical properties as those of TFTs having conventional Mo source/drain electrodes, we have obtained three important findings: (1 in typical TFT-LCD manufacturing processes, no Mn complex oxide layer is formed because Mn cannot diffuse substantially into an n+a-Si:H surface during low temperature (below 300°C processes and the growth of Mn complex oxide layer would also be limited by the absence of excess oxygen species; (2 a pre-formed silicon oxide layer much thicker than 1 nm severely degrades TFT electrical properties and therefore an ultrathin (≈1 nm silicon oxide layer is required to prevent the degradation; (3 Cu diffuses into an n+a-Si:H layer at oxygen-deficient spots and thus uniform surface oxidation is required to prevent the diffusion.

  3. Formation and Properties of New Ni-Based Amorphous Alloys with Critical Casting Thickness up to 5 mm

    National Research Council Canada - National Science Library

    Xu, Donghua

    2004-01-01

    ...) 40-50 K. Mechanical tests on these alloys show quite high Vicker's Hardness 780 to 862 kg/mm2, Young's modulus 111 to 134 GPa, shear modulus 40 to 50 GPa and high fracture strength 2.3 to 2.4 GPa...

  4. Short range structure of amorphous Ni50Ta50-alloys by means of X-ray- and neutron-diffraction

    International Nuclear Information System (INIS)

    Uhlig, H.; Lamparter, P.; Steeb, S.; Rohr, L.; Guentherodt, H.J.; Fischer, P.

    1992-01-01

    Amorphous Ni 50 Ta 50 -samples with their high crystallization temperature of 985 K were investigated. To evaluate the three partial structure factors of amorphous Ni 50 Ta 50 one X-ray diffraction experiment was performed with Ni 50 Ta 50 and two neutron diffraction experiments with Co 10 Ni 40 Ta 50 and with Ni 50 Ta 50 , respectively. The Bhatia-Thornton partial structure factor S cc (Q) indicates rather strong chemical short range order which also explains the premaximum observed in the Faber-Ziman partial S NiNi (Q)-function. The nearest neighbor distance is 2.82 A for Ni-Ni, 2.91 A for Ta-Ta, and is shortest for Ni-Ta, 2.44 A. The coordination numbers are N NiNi = 4.9, N TaTa = 8.2, and N NiTa = 6.0. We report on the chemical short range order and the possible binding behavior in a-Ni 50 Ta 50 and compare the present results with those reported in the literature on a-Ni 40 Ti 60 as well as on a-Ni 55 Ta 45 . (orig.)

  5. Mechanical spectroscopy study of the Cu36Zr59Al5 and Cu54Zr40Al6 amorphous alloys

    Directory of Open Access Journals (Sweden)

    Paulo Wilmar Barbosa Marques

    2012-12-01

    Full Text Available A mechanical spectroscopy study of Cu-Zr-Al bulk metallic glasses, was performed with two types of equipment: a Kê-type inverted torsion pendulum and an acoustic elastometer, working in the frequency ranges of Hz and kHz, respectively, with a heating rate of 1 K/min. The analysis of the anelastic relaxation shows similar spectra for both types of equipment resulting in internal friction patterns that vary with temperature and are not reproducible at each thermal cycle. The normalized of the square of the frequency changes from the first to later measurement cycles. These results indicate that the specimens of Cu-Zr-Al alloys were changing by mechanical relaxation, owing to the motion of atoms or clusters in the glassy state and possible "defects" produced during the processing of alloys.

  6. Microstructural evolution in decomposition of amorphous Zr41Ti14Cu12.5Ni10Be22.5 alloy, as investigated by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Liu Junming; Hahn-Meitner-Inst. Berlin, Bereich, NM; Nanjing Univ.

    1997-01-01

    Small angle neutron scattering (SANS) has been applied to investigate decomposition kinetics and microstructural evolution in amorphous Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 . It is detected that immediately after the alloy is submitted into the supercooled liquid range, phase separation develops rapidly in the early stage, leaving a sluggish coarsening stage. The decomposed alloy finally achieves a roughly regular microstructure which consists of one particle-like supercooled liquid phase embedded in the similarly disordered matrix. The morphology of the particles as a function of time is evaluated, predicting a bar-like pattern. Strong temperature dependence of the phase separation is observed. (orig.)

  7. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  8. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    pounds [2,3] renewed great interest in the study of high-temperature superconductivity. Fe-based systems are significantly different from the cuprates. The parent compounds in cuprates are antiferromagnetic Mott insulators, where the insulating property arises due to strong electron correlation compared to the width of their ...

  9. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  10. Characterization and amorphous phase formation of mechanically alloyed Co{sub 60}Fe{sub 5}Ni{sub 5}Ti{sub 25}B{sub 5} powders

    Energy Technology Data Exchange (ETDEWEB)

    Avar, Baris, E-mail: barisavar@beun.edu.tr [Department of Metallurgical and Materials Engineering, Bulent Ecevit University, Incivez, 67100 Zonguldak (Turkey); Ozcan, Sadan [SNTG Lab., Department of Physics Engineering, Hacettepe University, Beytepe, 06800 Ankara (Turkey)

    2015-11-25

    In this work, the multicomponent Co{sub 60}Fe{sub 5}Ni{sub 5}Ti{sub 25}B{sub 5} (at.%) alloy powders were synthesized from commercially available pure elemental powders by using a mechanical alloying (MA) process under argon gas atmosphere. The changes in structural, morphological, thermal and magnetic properties of the processed powders during MA were examined by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), differential thermal analysis (DTA) and vibrating sample magnetometer (VSM). The results showed that the amorphization occurred after 3.5 h of milling, and the amorphous phase was stable up to 580 °C, where crystallization occurred. The SEM observations indicated that different morphologies were obtained during the MA stages. In addition, the EDX mapping confirmed the uniform distribution of elemental content. Magnetic results indicated that all the samples exhibited soft-ferromagnetic behavior. The evolution of the saturation magnetization (Ms), the coercivity (Hc) and the squareness ratio (Ms/Mr) during milling process were discussed with respect to microstructural changes. The influence of the annealing on magnetic hysteresis was also studied. The Ms, Hc and Ms/Mr values of about 53.4 emu/g, 7.6 Oe and 0.01, respectively was obtained after 7 h of milling. - Highlights: • MA method was used to obtain amorphous phase in the multicomponent Co{sub 60}Fe{sub 5}Ni{sub 5}Ti{sub 25}B{sub 5} alloy. • Complete amorphization was feasible after 3.5 h of milling. • The amorphous phase was thermally stable up to 580 °C. • Different morphologies were obtained during the MA stages. • The magnetic properties were related to the microstructural changes.

  11. 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.

  12. Effect of Cu, Nb and Ta addition on the structural and magnetic properties of amorphous Fe-Si-B alloys

    International Nuclear Information System (INIS)

    Gupta, A.; Kane, S.N.; Bhagat, N.; Kulik, T.

    2003-01-01

    The effect of successive additions of Cu, Nb and Ta in amorphous Fe 77.5 Si 13.5 B 9 has been studied using X-ray diffraction and Moessbauer spectroscopy. Addition of Nb/Ta results in an increased near-neighbor distance as well as a decrease in topological order in the system. On the other hand, Cu addition results in a significant increase in the topological order. Addition of Cu does not significantly change the average hyperfine field, whereas, addition of Nb/Ta decreases the hyperfine field. Nb and Ta addition results in appearance of an additional hump in B hf around 13 T due to Fe atoms with Nb/Ta near neighbors. Thermal annealing of the specimens at 390 deg. C results in changes in the short-range order, which are mainly chemical in nature

  13. Amorphous-to-Cu51Zr14 phase transformation in Cu60Ti20Zr20 alloy

    International Nuclear Information System (INIS)

    Cao, Q P; Zhou, Y H; Horsewell, A; Jiang, J Z

    2003-01-01

    The kinetics of an amorphous-to-Cu 51 Zr 14 phase transformation in an as-cast Cu 60 Ti 20 Zr 20 rod have been investigated by differential scanning calorimetry. The relative volume fractions of the transferred crystalline phase as a function of annealing time, obtained at 713, 716, 723, 728, and 733 K, have been analysed in detail using 14 nucleation and growth models together with the JMA model. A time-dependent nucleation process is revealed. A steady-state nucleation rate of the order of 10 22 - 10 23 nuclei m -3 s -1 in the temperature range 713-733 K and an activation energy of the order of 550 kJmol -1 for the phase transformation in the as-cast Cu 60 Ti 20 Zr 20 rod were detected, for which some possible reasons are suggested

  14. Structural features and the microscopic dynamics of the three-component Zr{sub 47}Cu{sub 46}Al{sub 7} system: Equilibrium melt, supercooled melt, and amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Khusnutdinoff, R. M., E-mail: khrm@mail.ru; Mokshin, A. V., E-mail: anatolii.mokshin@mail.ru [Kazan Federal University (Russian Federation); Klumov, B. A.; Ryltsev, R. E.; Chtchelkatchev, N. M. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)

    2016-08-15

    The structural and dynamic properties of the three-component Zr{sub 47}Cu{sub 46}Al{sub 7} system are subjected to a molecular dynamics simulation in the temperature range T = 250–3000 K at a pressure p = 1.0 bar. The temperature dependences of the Wendt–Abraham parameter and the translation order parameter are used to determine the glass transition temperature in the Zr{sub 47}Cu{sub 46}Al{sub 7} system, which is found to be T{sub c} ≈ 750 K. It is found that the bulk amorphous Zr{sub 47}Cu{sub 46}Al{sub 7} alloy contains localized regions with an ordered atomic structures. Cluster analysis of configuration simulation data reveals the existence of quasi-icosahedral clusters in amorphous metallic Zr–Cu–Al alloys. The spectral densities of time radial distribution functions of the longitudinal (C̃{sub L}(k, ω)) and transverse (C̃{sub T}(k, ω)) fluxes are calculated in a wide wavenumber range in order to study the mechanisms of formation of atomic collective excitations in the Zr{sub 47}Cu{sub 46}Al{sub 7} system. It was found that a linear combination of three Gaussian functions is sufficient to reproduce the (C̃{sub L}(k, ω)) spectra, whereas at least four Gaussian contributions are necessary to exactly describe the (C̃{sub T}(k, ω)) spectra of the supercooled melt and the amorphous metallic alloy. It is shown that the collective atomic excitations in the equilibrium melt at T = 3000 K and in the amorphous metallic alloy at T = 250 K are characterized by two dispersion acoustic-like branches related with longitudinal and transverse polarizations.

  15. Fundamentals of amorphous solids structure and properties

    CERN Document Server

    Stachurski, Zbigniew H

    2014-01-01

    Long awaited, this textbook fills the gap for convincing concepts to describe amorphous solids. Adopting a unique approach, the author develops a framework that lays the foundations for a theory of amorphousness. He unravels the scientific mysteries surrounding the topic, replacing rather vague notions of amorphous materials as disordered crystalline solids with the well-founded concept of ideal amorphous solids. A classification of amorphous materials into inorganic glasses, organic glasses, glassy metallic alloys, and thin films sets the scene for the development of the model of ideal amorph

  16. Thin-film amorphous silicon alloy research partnership. Phase 2, Annual technical progress report, 2 February 1996--1 February 1997

    Energy Technology Data Exchange (ETDEWEB)

    Guha, S [United Solar Systems Corp., Troy, MI (United States)

    1997-06-01

    This is Phase II of a 3-phase, 3-year program. It is intended to expand, enhance, and accelerate knowledge and capabilities for developing high-performance, two-terminal multijunction amorphous Si alloy modules. We discuss investigations on back reflectors to improve cell performance and investigate uniformity in performance over a 1-sq.-ft. area. We present results on component cell performance, both in the initial and in the light-degraded states, deposited over a 1-sq.-ft. area. The uniformity in deposited is investigated by studying the performance of subcells deposited over the entire area. We also present results on the performance of triple- junction cells and modules. The modules use grid-lines and encapsulants compatible with our production technology. We discuss the novel laser-processing technique that has bee developed at United Solar to improve energy-conversion efficiency and reduce manufacturing costs. We discuss in detail the optimization of the processing steps, and the performance of a laser-processed, triple- junction device of 12.6 cm{sup 2} area is presented. We also present experimental results on investigations of module reliability.

  17. 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.

  18. Preparation and characterization of a ferrimagnetic amorphous alloy of GdCo entering the design of magnetic tunnel junctions: ionizing radiations hardness of magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Conraux, Y.

    2005-10-01

    The magnetic random access memories (MRAM) are on the way to supplant the other forms of random access memories using the states of electric charge, and this thanks to their many technical advantages: not-volatility, speed, low consumption power, robustness. Also, the MRAM are alleged insensitive with the ionizing radiations, which was not checked in experiments until now. The current architecture of the MRAM is based on the use of magnetic tunnel junctions (MTJ). These MRAM can present an important disadvantage, because they are likely of present errors of addressing, in particular when integration (density of memory cells) is increasingly thorough. The work undertaken during this thesis relates to these two points: - to check the functional reliability of the MRAM containing JTM exposed to high energy ionizing radiations; - to study a ferrimagnetic amorphous alloy, GdCo, likely to enter the composition of JTM and allowing to free from the possible errors of addressing by a process of thermal inhibition of the memory cells. This work of thesis showed that the MRAM containing JTM preserve their functional properties fully when they are subjected to intense ionizing radiations, and that GdCo is a very interesting material from the point of view of the solid state physics and magnetism, that its physical properties are very promising as for its applications, and that its integration in a JTM still claims technological developments. (author)

  19. Mechanical spectroscopy study on the Cu{sub 54}Zr{sub 40}Al{sub 6} amorphous matrix alloy at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Marques, P.W.B., E-mail: paulowilmar@df.ufscar.br [Departamento de Física, Universidade Federal de São Carlos, CP-676, São Carlos, SP (Brazil); Chaves, J.M.; Silva, P.S.; Florêncio, O. [Departamento de Física, Universidade Federal de São Carlos, CP-676, São Carlos, SP (Brazil); Moreno-Gobbi, A. [Instituto de Física, Facultad de Ciencias (UDELAR), Iguá 4225, CEP 11400 Montevideo (Uruguay); Aliaga, L.C.R.; Botta, W.J. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, CP-676, São Carlos, SP (Brazil)

    2015-02-05

    Highlights: • Cu{sub 54}Zr{sub 40}Al{sub 6} alloy was characterized by mechanical spectroscopy at low temperature. • Flexural and ultrasonic methods showed peaks associated to rearrangement of clusters. • The peaks less stable were associated with annihilation of Zr or Cu clusters. • MHz range can be favors the formation of Cu an Al-centered icosahedral structures. • TEM images show an increase in the size and number of crystal in amorphous matrix. - Abstract: A mechanical spectroscopy study of Cu{sub 54}Zr{sub 40}Al{sub 6} bulk metallic glasses composites was carried out in the kHz and MHz frequency ranges, by means of flexural and ultrasonic methods, respectively, in the temperature interval 150–300 K. In internal friction and attenuation curves at low temperature were observed peaks which were associated with distortions in the configuration of atomic clusters, which absorbed different quantities of energy due to short and medium order rearrangements. Changes within the clusters or atomic jumps between clusters occurring in the specimen induced the onset of polyamorphic peaks, since electronic interactions and bonding changed abruptly.

  20. Properties of a tunnel point contact between aluminum and the superconducting amorphous alloy NiZr2

    International Nuclear Information System (INIS)

    Gantmakher, V.F.; Golubov, A.A.; Osherov, M.V.

    1989-01-01

    The I-V characteristics of a tunnel point contact between aluminum and an amorphous ribbon resembling NiZr 2 in composition differ qualitatively from those of ordinary tunnel junctions between a superconductor and a normal metal. It is demonstrated that the observed curve shapes cannot be explained by accounting solely for one-particle tunneling in conditions of the proximity effect. This is followed by a qualitative discussion of a model in which the current rise at the potential eV equal to the gap width Δ (T) is generated by two-particle electron tunneling through the intermediate state which is manifested as a Cooper pair on the Fermi-level in the thin superconducting layer produced in the aluminum by the proximity effect. The current flowing through the contact will cause a breakdown of superconductivity in the vicinity of the contact at voltages exceeding the gap width. Smallness of the junction plays a decisive role both in inducing superconductivity for eV Δ

  1. Comparing the dynamic and thermodynamic behaviors of Al{sub 86}Ni{sub 9}-La{sub 5}/(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.H. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Wang, W.M. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: weiminw@sdu.edu.cn; Bian, X.F.; Zhang, J.T.; Li, R.; Wang, L. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-06-10

    The dynamic viscosities and thermodynamic dilatometric behaviors of Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys were investigated using viscometer, differential scanning calorimetry (DSC) and conventional dilatometer. Comparing with Al{sub 86}Ni{sub 9}La{sub 5} alloy, Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} alloy exhibits a larger viscosity and a larger average thermal expansion coefficient in the linear expansion zone ({alpha}{sub exp}). The viscosity and thermal expansion data suggest that the partial substitution La by Ce decreases the quantity of free volume in Al-Ni-La system by improving the continuous degree of atomic size, which leads to the improvement of glass forming ability.

  2. A High-Performance Corrosion-Resistant Iron-Based Amorphous Metal - The Effects of Composition, Structure and Environment on Corrosion Resistance

    International Nuclear Information System (INIS)

    Farmer, J.; Haslam, J.; Day, D.; Lian, T.; Saw, C.; Hailey, P.; Choi, J.S.; Rebak, R.; Yang, N.; Bayles, R.; Aprigliano, L.; Payer, J.; Perepezko, J.; Hildal, K.; Lavernia, E.; Ajdelsztajn, L.; Branagan, D.; Beardsley, B.

    2007-01-01

    The passive film stability of several Fe-based amorphous metal formulations have been found to be comparable to that of high-performance Ni-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). The high boron content of this particular amorphous metal also makes it an effective neutron absorber, and suitable for criticality control applications, as discussed in companion publications. Corrosion data for SAM2X5 (Fe 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 ) is discussed here. (authors)

  3. Superconductivity, magnetic susceptibility, and electronic properties of amorphous (Mo/sub 1-x/Ru/sub x/)/sub 80/P/sub 20/ alloys obtained by liquid quenching

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.L.; Poon, S.J.; Duwez, P.

    1977-11-01

    Results of x-ray diffraction, transmission electron diffraction, and crystallization studies on amorphous (Mo/sub 1-x/Ru/sub x/)/sub 80/P/sub 20/ alloys obtained by liquid quenching are presented and discussed. The alloys are all found to be superconducting with transition temperatures ranging from approximately 3/sup 0/K to approximately 9/sup 0/K. The variation of T/sub c/ with alloy composition is compared to that obtained by Collver and Hammond for vapor quenched transition metal films. Results of magnetic susceptibility measurements are used to estimate the variation of the electronic density of states at the Fermi level, N(0), from the Pauli paramagnetic contribution. The relationship between the variation of T/sub c/ and N(0) is discussed in terms of the microscope theory of superconductivity. Finally, results of measurements of the upper critical field H/sub c2/, and the normal state electronic transport properties are presented and compared with recent theoretical models for amorphous superconductors.

  4. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    International Nuclear Information System (INIS)

    Lavorato, G.C.; Fiore, G.; Castellero, A.; Baricco, M.; Moya, J.A.

    2012-01-01

    Amorphous alloys with composition (at%) Fe 48 Cr 15 Mo 14 C 15 B 6 Gd 2 (alloy A) and Fe 48 Cr 15 Mo 14 C 15 B 6 Y 2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness (∼13 GPa) and the Young modulus (∼180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  5. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    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.; Castellero, A.; Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [IESIING, Facultad de Ingenieria e Informatica, UCASAL, Salta (Argentina); CONICET (Argentina)

    2012-08-15

    Amorphous alloys with composition (at%) Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Gd{sub 2} (alloy A) and Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Y{sub 2} (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness ({approx}13 GPa) and the Young modulus ({approx}180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  6. The physics and applications of amorphous semiconductors

    CERN Document Server

    Madan, Arun

    1988-01-01

    This comprehensive, detailed treatise on the physics and applications of the new emerging technology of amorphous semiconductors focuses on specific device research problems such as the optimization of device performance. The first part of the book presents hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements. This boo

  7. Amorphous magnetism

    International Nuclear Information System (INIS)

    Rechenberg, H.R.

    1984-01-01

    The consequences of disorder on magnetic properties of solids are examined. In this context the word 'disorder' is not synonimous of structural amorphicity; chemical disorder can be achieved e.g. by randomly diffusing magnetic atoms on a nonmagnetic crystalline lattice. The name Amorphous Magnetism must be taken in a broad sense. (Author) [pt

  8. Amorphous nanophotonics

    CERN Document Server

    Scharf, Toralf

    2013-01-01

    This book represents the first comprehensive overview over amorphous nano-optical and nano-photonic systems. Nanophotonics is a burgeoning branch of optics that enables many applications by steering the mould of light on length scales smaller than the wavelength with devoted nanostructures. Amorphous nanophotonics exploits self-organization mechanisms based on bottom-up approaches to fabricate nanooptical systems. The resulting structures presented in the book are characterized by a deterministic unit cell with tailored geometries; but their spatial arrangement is not controlled. Instead of periodic, the structures appear either amorphous or random. The aim of this book is to discuss all aspects related to observable effects in amorphous nanophotonic material and aspects related to their design, fabrication, characterization and integration into applications. The book has an interdisciplinary nature with contributions from scientists in physics, chemistry and materials sciences and sheds light on the topic fr...

  9. 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.

  10. Influence of Cr Doping on the Critical Behavior of Amorphous Alloy Ribbons Fe78–xCrxSi4Nb5B12Cu1

    DEFF Research Database (Denmark)

    Phan, The-Long; Thanh, P. Q.; Chau, N.

    2014-01-01

    Though many previous works focused on studying Cr-doped Fe–Si–Nb–B–Cu amorphous alloys, magnetic-interaction mechanismsin these materials have not been carefully investigated yet. Dealing with these issues, we have prepared the amorphous alloy ribbonsFe78−xCrx Si4Nb5B12Cu1 with x = 1, 3, and 6, a...... = 0.367–0.376 and γ = 1.315–1.338. These values are close to those expected forthe 3-D Heisenberg model with β = 0.365 and γ = 1.336, proving the existence of short-range FM order in the amorphous alloyribbons....

  11. Hydrogen in disordered and amorphous solids

    International Nuclear Information System (INIS)

    Bambakidis, G; Bowman, R.C.

    1986-01-01

    This book presents information on the following topoics: elements of the theory of amorphous semiconductors; electronic structure of alpha-SiH; fluctuation induced gap states in amorphous hydrogenated silicon; hydrogen on semiconductor surfaces; the influence of hydrogen on the defects and instabilities in hydrogenated amorphous silicon; deuteron magnetic resonance in some amorphous semiconductors; formation of amorphous metals by solid state reactions of hydrogen with an intermetallic compound; NMR studies of the hydrides of disordered and amorphous alloys; neutron vibrational spectroscopy of disordered metal-hydrogen system; dynamical disorder of hydrogen in LaNi /SUB 5-y/ M /SUB y/ hydrides studied by quasi-elastic neutron scattering; recent studies of intermetallic hydrides; tritium in Pd and Pd /SUB 0.80/ Sg /SUB 0.20/ ; and determination of hydrogen concentration in thin films of absorbing materials

  12. The activation mechanism of Fe-based olefin metathesis catalysts

    Science.gov (United States)

    Poater, Albert; Pump, Eva; Vummaleti, Sai Vikrama Chaitanya; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts.

  13. Annealing-induced crystallization of the Er.sub.2./sub.Fe.sub.13.8./sub.B alloy amorphized by irradiation

    Czech Academy of Sciences Publication Activity Database

    Chukalkin, Y.G.; Teplykh, A. E.; Kudrevatykh, N. V.; Bogdanov, S.G.; Choo, K.N.; Lee, S.; Andreev, Alexander V.; Pirogov, A. N.

    2015-01-01

    Roč. 116, č. 3 (2015), s. 242-247 ISSN 0031-918X R&D Projects: GA ČR GAP204/12/0150 Institutional support: RVO:68378271 Keywords : permanent magnets * amorphous state * isochronous annealing * crystallization * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.794, year: 2015

  14. The crystal structure and electronic properties of a new metastable non-stoichiometric BaAl{sub 4}-type compound crystallized from amorphous La{sub 6}Ni{sub 34}Ge{sub 60} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Masashi [Institute for Materials Research, Tohoku University, Sendai, Katahira 980-8577 (Japan); Suzuki, Shoichiro [Institute for Materials Research, Tohoku University, Sendai, Katahira 980-8577 (Japan); Ohsuna, Tetsu [Institute for Materials Research, Tohoku University, Sendai, Katahira 980-8577 (Japan); Matsubara, Eiichiro [Institute for Materials Research, Tohoku University, Sendai, Katahira 980-8577 (Japan); Endo, Satoshi [Center for Low Temperature Science, Tohoku University, Sendai, Katahira 980-8577 (Japan); Inoue, Akihisa [Institute for Materials Research, Tohoku University, Sendai, Katahira 980-8577 (Japan)

    2004-11-17

    A new metastable La-Ge-Ni ternary BaAl{sub 4}-type (ThCr{sub 2}Si{sub 2}-type) compound, of which the space group is I4/mmm is synthesized. It is obtained by a polymorphic transformation from an La{sub 6}Ni{sub 34}Ge{sub 60} amorphous alloy on crystallizing. The formula of the compound is (La{sub 0.3}Ge{sub 0.7})(Ni{sub 0.85}Ge{sub 0.15}){sub 2}Ge{sub 2}. This indicates that it is highly non-stoichiometric compared to the stoichiometric LaNi{sub 2}Ge{sub 2}. It is found that the c-axis lattice parameter of this compound is much longer than that of LaNi{sub 2}Ge{sub 2}. It should be noted that the longer c-axis unit cell parameter is attributable only to the longer interlayer distance between Ge site and Ni site layers. The temperature dependences of electrical resistivity and thermoelectric power of the (La{sub 0.3}Ge{sub 0.7})(Ni{sub 0.85}Ge{sub 0.15}){sub 2}Ge{sub 2} compound and La{sub 6}Ni{sub 34}Ge{sub 60} amorphous alloy are also clarified. The comparison of these electronic properties between the two materials indicates that sp-electrons mainly contribute to the density of states around the Fermi level of this compound.

  15. Elaboration and evolution in temperature of the amorphous alloy Tb65Cu35, study of short and medium range atomic order and low temperature magnetic order related to the elaboration process

    International Nuclear Information System (INIS)

    El Gadi, M.

    1986-12-01

    The thesis presents the study of the amorphous metallic alloy Tb 65 Cu 35 prepared by rapid quenching and sputtering. Differential scanning calorimetry (DSC) measurements establish the annealing procedure needed to obtain a stable amorphous state through structural relaxation. Nearest neighbour distances as determined by neutron diffraction measurements shows a high coordination for Tb atom and a relatively low one for Cu atom. In addition, small-angle neutron scattering (SANS) experiments carried out as a function of temperature show the existence of Tb bubbles with very high magnetization at low-temperature. The region between the bubbles shows composition fluctuations. The SANS measurements also indicate the coexistence of phases with compositions bordering the eutectic value and in the form of domains having sizes of a few thousand Angstroms. An unexpected result in the observation of an hundred fold increase in the intensity of low-angle magnetic scattering when the samples are hand-polished with simple sand paper. This clearly indicates the importance of sample surface state. Finally, this work establishes that samples prepared by two different techniques show identical properties [fr

  16. Synthesis and densification of Cu added Fe-based BMG composite powders by gas atomization and electrical explosion of wire

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.C., E-mail: jckimpml@ulsan.ac.k [University of Ulsan, School of Materials Science and Engineering, Ulsan 680-749 (Korea, Republic of); Ryu, H.J.; Kim, J.S. [University of Ulsan, School of Materials Science and Engineering, Ulsan 680-749 (Korea, Republic of); Kim, B.K.; Kim, Y.J. [Department of Powder Materials, Korea Institute of Materials Science, Changwon 641-831 (Korea, Republic of); Kim, H.J. [Advanced Materials Division, Korea Institute of Industrial Technology, Incheon 406-130 (Korea, Republic of)

    2009-08-26

    In this study, the Fe-based (Fe-C-Si-B-P-Cr-Mo-Al) BMG powders were produced by the high pressure gas atomization process, and they were combined with the ductile Cu powders produced by the electrical explosion of wire (EEW). The Fe-based amorphous powders and Cu added BMG composite powders were compacted by the spark plasma sintering (SPS) processes into cylindrical shape. In the SPS press, the as-prepared powders were sintered at 793 K and 843 K. The relative density increased to 98% when the pressure increased up to 500 MPa by optimum control of the SPS process parameters. The micro-Vickers hardness was over 1100 Hv.

  17. Microstructure and functional properties of Fe73.5Cu1Nb3Si15.5B7 amorphous alloy

    Czech Academy of Sciences Publication Activity Database

    Blagojević, V. A.; Vasić, M.; David, Bohumil; Minić, Dušan M.; Pizúrová, Naděžda; Žák, Tomáš; Minić, Dragica M.

    2014-01-01

    Roč. 145, 1-2 (2014), s. 12-17 ISSN 0254-0584 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA ČR(CZ) GAP108/11/1350 Grant - others:Ministry of Education and Science of Serbia(SD) 172015 Institutional support: RVO:68081723 Keywords : amorphous materials * mechanical properties * magnetic properties * annealing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.259, year: 2014

  18. Modeling the amorphous structure of mechanically alloyed Ti{sub 50}Ni{sub 25}Cu{sub 25} using anomalous wide-angle x-ray scattering and reverse Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Grandi, T.A. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-09-01

    An amorphous Ti{sub 50}Ni{sub 25}Cu{sub 25} alloy was produced by 19 h of mechanical alloying. Anomalous wide angle x-ray scattering data were collected at six energies and six total scattering factors were obtained. By considering the data collected at two energies close to the Ni and Cu K edges, two differential anomalous scattering factors about the Ni and Cu atoms were obtained, showing that the chemical environments around these atoms are different. Eight factors were used as input data to the reverse Monte Carlo method used to compute the partial structure factors S{sub Ti3Ti}(K), S{sub Ti–Cu}(K), S{sub Ti–Ni}(K), S{sub Cu3Cu}(K), S{sub Cu–Ni}(K) and S{sub Ni–Ni}(K) and the partial pair distribution functions G{sub Ti3Ti}(r), G{sub Ti–Cu}(r), G{sub Ti–Ni}(r), G{sub Cu3Cu}(r), G{sub Cu–Ni}(r) and G{sub Ni–Ni}(r). From the RMC final atomic configuration and G{sub ij}(r) functions, the coordination numbers and interatomic atomic distances for the first neighbors were determined.

  19. Atomic Distribution in Catalytic Amorphous Metals

    Directory of Open Access Journals (Sweden)

    Sanghita Mridha

    2015-01-01

    Full Text Available The atomic distribution in catalytically active metallic glass alloys, Pd43Cu27Ni10P20 and Pt57.5Cu14.7Ni5.3P22.5, was investigated using three-dimensional atom probe microscopy. Atom probe analysis showed uniform distribution of constituent elements for both the starting amorphous alloys, with no phase separation. Both the crystallized alloys showed eutectic microstructure with a very sharp interface (~0.5 nm as determined from atom probe. The atomic distribution in the devitrified state is explained based on the “fragile liquid” behavior for these noble-metal glassy alloys.

  20. Synthesis and structural characterization of amorphous alloys of the Fe-Ni-B type; Sintesis y caracterizacion estructural de aleaciones amorfas del tipo Fe-Ni-B

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Jimenez B, J.; Garcia S, I. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    It was prepared the alloy FeNiB for chemical reduction, using four p H values (5, 6, 7 and 7.5). To p H=6 partially oxidized particles were obtained, between 16 and 20%. In the synthesis to other p H values, the obtained particles were highly oxidized (65-90%) according to the X-ray diffraction results, in all the preparations the particles were partially crystallized, with crystal size that varied between 4 and 10 nm. The structure of these particles can be consider that they are formed by a nucleus due to the alloy and an oxide armor recovering it. (Author)

  1. Corrosion aspects of Ni-Cr-Fe based and Ni-Cu based steam generator tube materials

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, R.S., E-mail: rsdutta@barc.gov.i [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2009-09-01

    This paper reviews corrosion related issues of Ni-Cr-Fe based (in a general sense) and Ni-Cu based steam generator tube materials for nuclear power plants those have been dealt with for last more than four decades along with some updated information on corrosion research. The materials include austenitic stainless steels (SSs), Alloy 600, Monel 400, Alloy 800 and Alloy 690. Compatibility related issues of these alloys are briefly discussed along with the alloy chemistry and microstructure. For austenitic SSs, stress corrosion cracking (SCC) behaviour in high temperature aqueous environments is discussed. For Alloy 600, intergranular cracking in high temperature water including hydrogen-induced intergranular cracking is highlighted along with the interactions of material in various environments. In case of Monel 400, intergranular corrosion and pitting corrosion at ambient temperature and SCC behaviour at elevated temperature are briefly described. For Alloy 800, the discussion covers SCC behaviour, surface characterization and microstructural aspects of pitting, whereas hydrogen-related issues are also highlighted for Alloy 690.

  2. Corrosion aspects of Ni-Cr-Fe based and Ni-Cu based steam generator tube materials

    International Nuclear Information System (INIS)

    Dutta, R.S.

    2009-01-01

    This paper reviews corrosion related issues of Ni-Cr-Fe based (in a general sense) and Ni-Cu based steam generator tube materials for nuclear power plants those have been dealt with for last more than four decades along with some updated information on corrosion research. The materials include austenitic stainless steels (SSs), Alloy 600, Monel 400, Alloy 800 and Alloy 690. Compatibility related issues of these alloys are briefly discussed along with the alloy chemistry and microstructure. For austenitic SSs, stress corrosion cracking (SCC) behaviour in high temperature aqueous environments is discussed. For Alloy 600, intergranular cracking in high temperature water including hydrogen-induced intergranular cracking is highlighted along with the interactions of material in various environments. In case of Monel 400, intergranular corrosion and pitting corrosion at ambient temperature and SCC behaviour at elevated temperature are briefly described. For Alloy 800, the discussion covers SCC behaviour, surface characterization and microstructural aspects of pitting, whereas hydrogen-related issues are also highlighted for Alloy 690.

  3. 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.)

  4. Application of Fe-based metallic glasses in wastewater treatment

    International Nuclear Information System (INIS)

    Lin Bao; Bian Xiufang; Wang Pan; Luo Guanping

    2012-01-01

    Highlights: ► We found the Fe-based metallic glasses have potential application in wastewater treatment. ► The corrosion on the surface of Fe-based metallic glasses is related to the application. ► We set a new theory to explain the process of degredation organic metters with Fe-based metallic glasses. - Abstract: This work pioneered the use of the Fe 78 Si 9 B 13 metallic glass ribbons in wastewater treatment. Fe 78 Si 9 B 13 metallic glass was employed to remediate wastewater contaminated with a mixture of organic dyes. The removal rate of chemical oxygen demand (COD) with Fe 78 Si 9 B 13 metallic glass and metallic Fe 0 was up to 23 ± 0.93% in 30 min and 21 ± 0.67% with in 45 min, respectively. The dosage of Fe-based metallic glass was only 1/25 of that of metallic Fe 0 to obtain equivalent effects. The mechanism of wastewater treatment through Fe-based metallic glasses is discussed.

  5. The activation mechanism of Fe-based olefin metathesis catalysts

    KAUST Repository

    Poater, Albert

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts. © 2014 Elsevier B.V.

  6. Bulk amorphous alloys: Preparation and properties of (Mg0.98Al0.02)x(Cu0.75Y0.25)100

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Pedersen, Allan Schrøder; Ohnuma, M.

    2000-01-01

    for the influence of the Mg-Al content on the glass forming ability by studying a range of compositions, (Mg0.98Al0.02)(x)(Cu0.75Y0.25)(100-x) for x = 60 - 80 at.%. As previously, the alloys were prepared by a relatively simple technique, i.e. rapid cooling of the melt in a wedge-shaped copper mould. This method...

  7. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Fuel performance codes approximate this complex behavior using an axisymmetric, axially-stacked, one-dimensional radial representation to save computation cost. However, the need for improved modeling of PCMI and, particularly, the importance of multidimensional capability for accurate fuel performance simulation has been identified as safety margin decreases. Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed

  8. Calorimetric studies of non-isothermal crystallization in amorphous

    Indian Academy of Sciences (India)

    Administrator

    The applicability of Meyer–Neldel relation between the pre-exponential factor and activation energy of non-isothermal crystallization for amorphous alloys of Cu–Ti system was verified. Keywords. Amorphous materials; differential scanning calorimetry (DSC); phase transitions. 1. Introduction. There is a significant attention ...

  9. The study on surface chemical modification of Fe{sub 71.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9}V{sub 2} amorphous alloy ribbons and its piezomagnetic effect

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jie; Zhu, Zhenghou, E-mail: z00708@sina.com

    2016-12-01

    In this paper, a type of smooth even endogeny conversion coat composed of Cu{sub 0.86}Fe{sub 2.14}O{sub 4} and (Cu{sub 0.18}Fe{sub 0.82})Cu{sub 0.82}Fe{sub 1.18}O{sub 4} phases was successfully obtained by a conversion reaction on the surfaces of Fe{sub 71.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9}V{sub 2} amorphous alloy ribbons. In this way, its ribbon thickness was decreased about 6–8 µm equivalently. The phase composition and microstructure of the conversion coat were investigated by XRD and SEM. In addition, the adhesion test of epoxy resin and amorphous alloy ribbon was verified by dipping experiments. It is found that the interface bonding strength between the conversion coat and ribbons is strong comparatively. On one hand, the proper interface between conversion coat and epoxy resin make it easy for ribbons to be encapsulated; on the other hand, the ribbons perform better significant piezomagnetic effect than the untreated ones due to a thinner thickness. This work may be a good basic for the applications of Fe{sub 71.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9}V{sub 2} amorphous alloy ribbons in piezomagnetic sensor and other devices based on the piezomagnetism effect. - Highlights: • A conversion coat was successfully obtained on the surfaces of amorphous alloy ribbons. • The encapsulated problem was solved by the conversion coats. • The ribbon after reaction had a better piezomagnetic sensitivity.

  10. Fabrication of Fe-Based Diamond Composites by Pressureless Infiltration

    Directory of Open Access Journals (Sweden)

    Meng Li

    2016-12-01

    Full Text Available A metal-based matrix is usually used for the fabrication of diamond bits in order to achieve favorable properties and easy processing. In the effort to reduce the cost and to attain the desired bit properties, researchers have brought more attention to diamond composites. In this paper, Fe-based impregnated diamond composites for drill bits were fabricated by using a pressureless infiltration sintering method at 970 °C for 5 min. In addition, boron was introduced into Fe-based diamond composites. The influence of boron on the density, hardness, bending strength, grinding ratio, and microstructure was investigated. An Fe-based diamond composite with 1 wt % B has an optimal overall performance, the grinding ratio especially improving by 80%. After comparing with tungsten carbide (WC-based diamond composites with and without 1 wt % B, results showed that the Fe-based diamond composite with 1 wt % B exhibits higher bending strength and wear resistance, being satisfactory to bit needs.

  11. Technique for determination of elastic limit of micron band-thick amorphous

    International Nuclear Information System (INIS)

    Zakharov, E.K.; Pol'dyaeva, G.P.; Tret'yakov, B.N.

    1984-01-01

    A method is suggested to determine the elastic limit of micron-thick amorphous band under bending. The elastic limit is determined by bending an amorphous band sample around a series of cylindrical mandrels of gradually decreasing radius. Experimental data on measuring the elastic limit of some amorphous iron base alloys according to the suggested technique are presented. The elastic limit of amorphous alloys is shown to lie in the 3140-4110 MPa range depending on chemical composition, which is about 2-2.5 times higher as compared to high-strength crystal alloys

  12. Preparation and characterization of a ferrimagnetic amorphous alloy of GdCo entering the design of magnetic tunnel junctions: ionizing radiations hardness of magnetic tunnel junctions; preparation et caracterisation d'un alliage amorphe ferrimagnetique de GdCo entrant dans la conception de jonctions tunnel magnetiques. Resistance des jonctions tunnel magnetiques aux rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Conraux, Y

    2005-10-15

    The magnetic random access memories (MRAM) are on the way to supplant the other forms of random access memories using the states of electric charge, and this thanks to their many technical advantages: not-volatility, speed, low consumption power, robustness. Also, the MRAM are alleged insensitive with the ionizing radiations, which was not checked in experiments until now. The current architecture of the MRAM is based on the use of magnetic tunnel junctions (MTJ). These MRAM can present an important disadvantage, because they are likely of present errors of addressing, in particular when integration (density of memory cells) is increasingly thorough. The work undertaken during this thesis relates to these two points: - to check the functional reliability of the MRAM containing JTM exposed to high energy ionizing radiations; - to study a ferrimagnetic amorphous alloy, GdCo, likely to enter the composition of JTM and allowing to free from the possible errors of addressing by a process of thermal inhibition of the memory cells. This work of thesis showed that the MRAM containing JTM preserve their functional properties fully when they are subjected to intense ionizing radiations, and that GdCo is a very interesting material from the point of view of the solid state physics and magnetism, that its physical properties are very promising as for its applications, and that its integration in a JTM still claims technological developments. (author)

  13. Cobalt-boron amorphous alloy prepared in water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion as anode for alkaline secondary batteries

    International Nuclear Information System (INIS)

    Tong, D.G.; Wang, D.; Chu, W.; Sun, J.H.; Wu, P.

    2010-01-01

    Amorphous cobalt-boron (Co-B) with uniform nanoparticles was prepared for the first time via reduction of cobalt acetate by potassium borohydride in the water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion system. The sample was characterized by X-ray diffraction, transmission electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, inductively coupled plasma, cyclic voltammetry, differential scanning calorimetry, temperature-programmed desorption, scanning electron microscopy, charge-discharge test and electrochemical impedance spectra. The results demonstrate that electrochemical activity of the as-synthesized Co-B was higher than that of the regular Co-B prepared in aqueous solution. It indicates that the homogeneous distribution and large specific surface area helped the electrochemical hydrogen storage of the as-synthesized Co-B. Furthermore, the as-synthesized Co-B even had 347 mAh g -1 after 50 cycles, while the regular Co-B prepared in aqueous solution only had 254 mAh g -1 after 30 cycles at a current of 100 mA g -1 . The better cycling performance can be ascribed to its smaller interfacial impedance between electrode and electrolyte.

  14. Effects of Co, Ni, and Cr addition on microstructure and magnetic properties of amorphous and nanocrystalline Fe86−xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6 alloys

    Directory of Open Access Journals (Sweden)

    Łukiewska Agnieszka

    2015-03-01

    Full Text Available Mössbauer spectra and thermomagnetic curves for the Fe86−xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6 alloys in the as-quenched state and after the accumulative annealing in the temperature range 600–800 K for 10 min are investigated. The parent Fe86Zr7Nb2Cu1B4 amorphous alloy is paramagnetic at room temperature, and substitution of 6 at.% of Fe by Co, Ni, and CoCr changes the magnetic structure – the alloys become ferromagnetic, whereas replacing 6 at.% of Fe with Cr preserves the paramagnetic state. After the heat treatment at 600 K, the decrease of the average hyperfine field induction, as compared to the as-quenched state, is observed due to the invar effect. After this annealing, the Curie temperature for all investigated alloys decreases. The accumulative annealing up to 800 K leads to the partial crystallization; α-Fe or α-FeCo grains with diameters in the range of 12–30 nm in the residual amorphous matrix appear.

  15. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  16. Castable hot corrosion resistant alloy

    Science.gov (United States)

    Barrett, Charles A. (Inventor); Holt, William H. (Inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  17. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed. Nuclear fuel operates in an extreme environment that induces complex multiphysics phenomena, occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. This multiphysics behavior is often tightly coupled, a well known example being the thermomechanical behavior. Adding to this complexity, important aspects of fuel behavior are inherently

  18. Computational and Experimental Design of Fe-Based Superalloys for Elevated-Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter K. [Univ. of Tennessee, Knoxville, TN (United States); Fine, Morris E. [Northwestern Univ., Evanston, IL (United States); Ghosh, Gautam [Northwestern Univ., Evanston, IL (United States); Asta, Mark D. [Univ. of California, Berkeley, CA (United States); Liu, Chain T. [Auburn Univ., AL (United States); Sun, Zhiqian [Univ. of Tennessee, Knoxville, TN (United States); Huang, Shenyan [Univ. of Tennessee, Knoxville, TN (United States); Teng, Zhenke [Univ. of Tennessee, Knoxville, TN (United States); Wang, Gongyao [Univ. of Tennessee, Knoxville, TN (United States)

    2012-04-13

    Analogous to nickel-based superalloys, Fe-based superalloys, which are strengthened by coherent B2- type precipitates are proposed for elevated-temperature applications. During the period of this project, a series of ferritic superalloys have been designed and fabricated by methods of vacuum-arc melting and vacuum-induction melting. Nano-scale precipitates were characterized by atom-probe tomography, ultrasmall- angle X-ray scattering, and transmission-electron microscopy. A duplex distribution of precipitates was found. It seems that ferritic superalloys are susceptible to brittle fracture. Systematic endeavors have been devoted to understanding and resolving the problem. Factors, such as hot rolling, precipitate volume fractions, alloy compositions, precipitate sizes and inter-particle spacings, and hyperfine cooling precipitates, have been investigated. In order to understand the underlying relationship between the microstructure and creep behavior of ferric alloys at elevated temperatures, in-situ neutron studies have been carried out. Based on the current result, it seems that the major role of β' with a 16%-volume fraction in strengthening ferritic alloys is not load sharing but interactions with dislocations. The oxidation behavior of one ferritic alloy, FBB8 (Fe-6.5Al-10Ni-10Cr-3.4Mo-0.25Zr-0.005B, weight percent), was studied in dry air. It is found that it possesses superior oxidation resistance at 1,023 and 1,123 K, compared with other creep-resistant ferritic steels [T91 (modified 9Cr-1Mo, weight percent) and P92 (9Cr-1.8W-0.5Mo, weight percent)]. At the same time, the calculation of the interfacial energies between the -iron and B2-type intermetallics (CoAl, FeAl, and NiAl) has been conducted.

  19. Microstructural and mechanical properties analysis of an aluminium matrix composite reinforced with the amorphous alloy Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidated by hot extrusion; Propriedades mecanicas e microestruturais de um composito com matrix de aluminio e reforco amorfo de Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidado por extrusao a quente por extrusao a quente

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Peres, M.M., E-mail: peresmm@yahoo.com.b [Universidade Federal de Itajuba (UNIFEI), Itabira, MG (Brazil)

    2010-07-01

    The aim of this work is the microstructure and the mechanical properties analysis of an aluminium matrix composite reinforced with the Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} amorphous alloy. The amorphous alloy was produced by melt-spinning and fragmented in powder particles by milling. Pure aluminium power was moistured with amorphous powder in a proportion of 80:20 (% weight) and processed by milling using 350 rpm during 30 minutes for the generation of a homogeneous composite powder. This product was consolidated by extrusion at 235 deg C, ram speed of 2mm/min and extrusion ratio of 7/1, generating a compact and cylindrical bar with 3 mm of width. The result sample was characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and by X-Ray Diffraction (XRD). Microhardness and compression tests show an improvement on the mechanical properties. (author)

  20. Ultrafast probes of coherent oscillations in Fe-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. W. [Dept. of Physics, Chungbuk National University, Cheongju (Korea, Republic of)

    2017-03-15

    Forefront ultrafast experimental techniques have recently proven their potential as new approaches to understand materials based on non-equilibrium dynamics in the time domain. The time domain approach is useful especially in disentangling complicated coupling among charge, spin and lattice degrees of freedom. Various ultrafast experiments on Fe-based superconductors have observed strong coherent oscillations of an A1g phonon mode of arsenic ions, which shows strong coupling to the electronic and magnetic states. This paper reviews the recent reports of ultrafast studies on Fe-based superconductor with a focus on the coherent oscillations. Experimental results with ultrashort light sources from the terahertz-infrared pulses to the hard X-rays from a free electron laser will be presented.

  1. Nanoscale Investigation of New Fe-Based Superconductors

    Science.gov (United States)

    2012-10-15

    12-10-2012 4. TITLE AND SUBTITLE Nanoscale Investigation of New Iron - Based Superconductors 5a. CONTRACT NUMBER FA23861114054 5b. GRANT NUMBER 5c...Final Report for AOARD Grant 114054 “Nanoscale Investigation of New Fe- based Superconductors ” Date: October 15, 2012 Name of Principal...particles [5]. These results indicate that interesting phenomena may happen in iron chalcogenide superconductors when their size goes to nanometer

  2. The supercooled liquid region span of Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ferenc, Jaroslaw, E-mail: jferenc@inmat.pw.edu.p [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw (Poland); Erenc-Sedziak, Tatiana; Kowalczyk, Maciej; Kulik, Tadeusz [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw (Poland)

    2010-04-16

    This work presents the results of the study of the magnetically soft, iron-based bulk metallic glasses, from the viewpoint of their ability to deform in the supercooled liquid region and to resist the tendency to crystallise. The calorimetric measurements of glass transition and crystallisation temperatures (T{sub g} and T{sub x1} respectively) were employed, accompanied by the measurements of magnetic properties as the monitor of structural changes after heat treatment. It was found that the widest supercooled liquid region was obtained when zirconium was selected as one of the alloying elements, yielding the T{sub x1}-T{sub g} span of about 70 {sup o}C. Also, it was observed that the values of T{sub g} and T{sub x} may be controlled by the proportions of the main elements (Fe, Co, Ni), and the glass forming elements (such as B, Nb, Zr). As a guideline, it is suggested that the glassy Fe-based alloys may be maintained in the supercooled liquid state without crystallisation for several minutes, if T{sub x1}-T{sub g} is wider than 50 {sup o}C. Basing on this estimation, calorimetric measurements may be a good indicator of the ability of bulk metallic glasses to be suitable for superplastic compaction into larger shapes.

  3. Preliminary Results on the Surface of a New Fe-Based Metallic Material after “In Vivo” Maintaining

    Science.gov (United States)

    Săndulache, F.; Stanciu, S.; Cimpoeşu, N.; Stanciu, T.; Cimpoeșu, R.; Enache, A.; Baciu, R.

    2017-06-01

    Abstract A new Fe-based alloy was obtained using UltraCast melting equipment. The alloy, after mechanical processing, was implanted in five rabbit specimens (with respect for the “in-bone” procedure). After 30 days of implantation the samples were recovered and analyzed by weight and surface state meanings. Scanning electron microscopy technique was used to determine the new compounds morphology from the metallic surface and X-ray dispersive energy spectroscopy for chemical analyze results. A bond between the metallic material and biological material of the bone was observed through increasing of sample weight and by SEM images. After the first set of tests, as the samples were extracted and biologically cleaned, the samples were ultrasonically cleaned and re-analyzed in order to establish the stability of the chemical compounds.

  4. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings

    International Nuclear Information System (INIS)

    Farmer, J C; Haslam, J J; Wong, F; Ji, X; Day, S D; Branagan, D J; Marshall, M C; Meacham, B E; Buffa, E J; Blue, C A; Rivard, J K; Beardsley, M B; Weaver, D T; Aprigliano, L F; Kohler, L; Bayles, R; Lemieux, E J; Wolejsza, T M; Martin, F J; Yang, N; Lucadamo, G; Perepezko, J H; Hildal, K; Kaufman, L; Heuer, A H; Ernst, F; Michal, G M; Kahn, H; Lavernia, E J

    2004-01-01

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an ''integral drip shield'' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent

  5. Calculations of the magnetic entropy change in amorphous through a microscopic anisotropic model: Applications to Dy{sub 70}Zr{sub 30} and DyCo{sub 3.4} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Nóbrega, E. P.; Ribeiro, P. O.; Alvarenga, T. S. T.; Lopes, P. H. O.; Sousa, V. S. R. de; Oliveira, N. A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro—UERJ, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro (Brazil); Alho, B. P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 Rio de Janeiro (Brazil); Carvalho, G. [Laboratório Nacional de Luz Sincroton—LNLS, 13083-970 Campinas, São Paulo (Brazil); Magnus, A.

    2014-10-14

    We report theoretical investigations on the magnetocaloric effect, described by the magnetic entropy change in rare earth—transition metal amorphous systems. The model includes the local anisotropy on the rare earth ions in Harris-Plischke-Zuckermann assumptions. The transition metals ions are treated in terms of itinerant electron ferromagnetism and the magnetic moment of rare earth ions is coupled to the polarized d-band by a local exchange interaction. The magnetocaloric effect was calculated in DyCo{sub 3.4} system, which presents amorphous sperimagnetic configuration. The calculations predict higher refrigerant capacity in the amorphous DyCo{sub 3.4} than in DyCo{sub 2} crystal, highlighting the importance of amorphous magnetocaloric materials. Our calculation of the magnetocaloric effect in Dy{sub 70}Zr{sub 30}, which presents amorphous asperomagnetic configuration, is in good agreement with the experimental result. Furthermore, magnetic entropy changes associated with crystal-amorphous configurations change are estimated.

  6. Structural relaxation and low-field magnetic properties of bulk amorphous Fe{sub 75-x}Al{sub 5}P{sub 11}Ga{sub x}B{sub 4}C{sub 5} (x=0, 2 or 5) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lukiewska, A. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland)]. E-mail: aluk@mim.pcz.czest.pl; Zbroszczyk, J. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Ciurzynska, W. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Olszewski, J. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Pawlik, P. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Hasiak, M. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Nabialek, M. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Swierczek, J. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Lukiewski, M. [ELHAND Transformers, ul. PCK 22, 42-700 Lubliniec (Poland)

    2006-09-15

    Structure relaxations and low-field magnetic properties of the thick amorphous Fe{sub 75-x}Al{sub 5}P{sub 11}Ga{sub x}B{sub 4}C{sub 5} (x=0, 2 or 5) ribbons subjected to accumulative annealing below the crystallization temperature are investigated. From Mossbauer spectroscopy studies we have found that the average hyperfine field slighty increases after the heat treatment of the samples due to structure relaxations. The intensity of the magnetic susceptibility disaccommodation decreases with the thickness of ribbons. It may be connected with annealing out of some free volumes during the sample preparation. Moreover, we have stated that core losses of the investigated alloys are comparable with those of conventional amorphous materials.

  7. Fe-based magnetic nanomaterials: Wet chemical synthesis, magnetic properties and exploration on applications

    Science.gov (United States)

    Xiaoliang, Hong

    Even though the start of research based on Fe-based magnetic nanomaterials could be dated back to hundreds years ago, the considerably large amount of emerging fields for their applications, including spintronic structures in information storage, biomedical and environmental applications, magnetic sensors, magnetic energy harvesters, has spurred renewed interest on the application-related properties of Fe-based nanomaterial in both the nanoparticle and film forms. Besides, an exploration of a simple, wide, effective technique that can be used for growth of high-quality Fe-based magnetic nanoparticles and films is of great importance for better materialization of these potential Fe-based devices. This thesis mainly focuses on fabricating different magnetic Fe-based materials (ferrites and ferrous alloys, nanoparticle and film) with wet chemical method, investigating their growth mechanism and magnetic and electrical properties. In addition, the possible applications of as-fabricated Fe-based nanoparticles and films are studied. The contribution of the work is summarized as below: (1) Investigation indicated that the external magnetic field plays an important role in determining the microstructure, magnetic properties of the Fe3O4 nanoparticles. The magnetic field can promote the change of Fe3O4 nanocuboctahedrons to nanocubes. Compared the hyperthermia property of as-fabricated nanocuboctahedrons and nanocubes Fe3O4, the intrinsic loss power (ILP) of the Fe3O4 nanocubes was much higher than that of nanocuboctahedrons due to the surface magnetic effect. (2) A general and facile method for broadly deposition of thick Fe 3O4 film and other ferrites has been demonstrated. It had been found that the epitaxial high-quality Fe3O4 film could be deposited either on MgO substrates directly or Si substrates with Fe3O4 seed layer deposited by PLD. As-deposited Fe 3O4 film could be easily patterned and shows potential applications for microwave and MEMS supercapacitor. Besides

  8. Processing and alloying of tungsten heavy alloys

    International Nuclear Information System (INIS)

    Bose, A.

    1993-01-01

    Tungsten heavy alloys are two-phase metal matrix composites with a unique combination of density, strength, and ductility. They are processed by liquid-phase sintering of mixed elemental powders. The final microstructure consists of a contiguous network of nearly pure tungsten grains embedded in a matrix of a ductile W-Ni-Fe alloy. Due to the unique property combination of the material, they are used extensively as kinetic energy penetrators, radiation shields. counterbalances, and a number of other applications in the defense industry. The properties of these alloys are extremely sensitive to the processing conditions. Porosity levels as low as 1% can drastically degrade the properties of these alloys. During processing, care must be taken to reduce or prevent incomplete densification, hydrogen embrittlement, impurity segregation to the grain boundaries, solidification shrinkage induced porosity, and in situ formation of pores due to the sintering atmosphere. This paper will discuss some of the key processing issues for obtaining tungsten heavy alloys with good properties. High strength tungsten heavy alloys are usually fabricated by swaging and aging the conventional as-sintered material. The influence of this on the shear localization tendency of a W-Ni-Co alloy will also be demonstrated. Recent developments have shown that the addition of certain refractory metals partially replacing tungsten can significantly improve the strength of the conventional heavy alloys. This development becomes significant due to the recent interest in near net shaping techniques such as powder injection moldings. The role of suitable alloying additions to the classic W-Ni-Fe based heavy alloys and their processing techniques will also be discussed in this paper

  9. Superconducting and normal properties of metallic amorphous systems

    International Nuclear Information System (INIS)

    Esquinazi, P.D.

    1983-02-01

    The superconducting and transport properties (superconducing critical temperature, superconducting critical currents, electric resistivity and thermal conductivity) of the amorphous alloys La 70 Cu 30 and Zr 70 Cu 30 prepared by melt spinning have been investigated. The modification of these properties when, the initial amorphous metals relax to other metastable state under thermal treatment at below crystallization temperatures, have also been studied. (M.E.L.) [es

  10. Fe-based bulk metallic glasses used for magnetic shielding

    Science.gov (United States)

    Şerban, Va; Codrean, C.; Uţu, D.; Ercuţa, A.

    2009-01-01

    The casting in complex shapes (tubullar) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small adittion of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  11. Fe-based bulk metallic glasses used for magnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Va; Codrean, C; UTu, D [Politehnica University of Timisoara, Depart for Materials Science and Welding, 1, M. Viteazu Bvd., 300222, Timisoara (Romania); ErcuTa, A, E-mail: serban@mec.upt.r [West University of Timisoara, Faculty of Physics, 4, Vasile Parvan Bdv., Timisoara 300223 (Romania)

    2009-01-01

    The casting in complex shapes (tubular) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small addition of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  12. Amorphous phase formation in the Cu{sub 36}Zr{sub 59}A{sub l5} and Cu{sub 48}Zr{sub 43}A{sub l9} ternary alloys studied by molecular dynamics; Estudo da formacao de fase amorfa nas ligas ternarias Cu{sub 36}Zr{sub 59}A{sub l5} e Cu{sub 48}Zr{sub 43}A{sub l9} por dinamica molecular

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Schimidt, C.S.; Lima, L.V.; Domingues, G.M.B.; Bastos, I.N., E-mail: aliaga@iprj.uer.br [Universidade do Estado do Rio de Janeiro (UERJ), Nova friburgo, RJ (Brazil). Departamento de Materiais

    2016-07-01

    Amorphous alloys presents better mechanical and physical properties than its crystalline counterparts. However, there is a scarce understanding on structure - properties relationship in this class of materials. This paper presents the results of the molecular dynamics application to obtain an atomistic description of melting, solidification and the glass forming ability in the ternary Cu{sub 36}Zr{sub 59}A{sub l5} and Cu{sub 48}Zr{sub 43}A{sub l9} alloys. In the study we used the EAM potential and different cooling rates, β = 0.1, 1 and 100 K/ps to form the amorphous phase in a system consisting of 32,000 atoms by using the free code LAMMPS. The solidus and liquidus temperatures, on a heating rate of the 5 K/ps, were obtained. Also, on the cooling down step, it was observed that the glass transition temperature (T{sub g}) decreases as cooling rate increases. The structural evolution was analyzed through the radial distribution functions and Voronoi polyhedra. Furthermore, it was determined the evolution of viscosity upper T{sub g}, as well as the fragility (m) parameter for each amorphous alloy. The thermal parameters of the simulation obtained are compared with those of the experiments. (author)

  13. Structural and magnetic properties on the Fe-B-P-Cu-W nano-crystalline alloy system

    Science.gov (United States)

    Zhang, Yan; Wang, Yaocen; Makino, Akihiro

    2018-04-01

    In the present article, the structural and soft magnetic properties of Fe-B-P-Cu alloy system with W addition have been studied as well as the annealing configurations required for magnetic softness. It is found that the substitution of B by W deteriorates the soft magnetic properties after annealing. The reason of such impact with W addition may lie in the insufficient bonding strength between W and B so that the addition of W is not effective enough to suppress grain growth against the high concentration and high crystallization tendency of Fe during annealing. The addition of 4 at.% W is also found to reduce the saturation magnetization of the nano-crystalline alloy by 14%. It is also found that the addition of P in the Fe-based alloys could help reduce the coercivity upon annealing with high heating rate. The existence of P could also help slightly increase the overall saturation magnetization by enhancing the electron transfer away from Fe in the residual amorphous structure.

  14. Studies of hydrogenated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, S G; Carlos, W E

    1984-07-01

    This report discusses the results of probing the defect structure and bonding of hydrogenated amorphous silicon films using both nuclear magnetic resonance (NMR) and electron spin resonance (ESR). The doping efficiency of boron in a-Si:H was found to be less than 1%, with 90% of the boron in a threefold coordinated state. On the other hand, phosphorus NMR chemical shift measurements yielded a ration of threefold to fourfold P sites of roughly 4 to 1. Various resonance lines were observed in heavily boron- and phosphorus-doped films and a-SiC:H alloys. These lines were attributed to band tail states on twofold coordinated silicon. In a-SiC:H films, a strong resonance was attributed to dangling bonds on carbon atoms. ESR measurements on low-pressure chemical-vapor-deposited (LPCVD) a-Si:H were performed on samples. The defect density in the bulk of the films was 10/sup 17//cc with a factor of 3 increase at the surface of the sample. The ESR spectrum of LPCVD-prepared films was not affected by prolonged exposure to strong light. Microcrystalline silicon samples were also examined. The phosphorus-doped films showed a strong signal from the crystalline material and no resonance from the amorphous matrix. This shows that phosphorus is incorporated in the crystals and is active as a dopant. No signal was recorded from the boron-doped films.

  15. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud

    2012-01-01

    Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  16. Thermodynamic analysis and purifying an amorphous phase of frozen crystallization centers

    Science.gov (United States)

    Lysov, V. I.; Tsaregradskaya, T. L.; Turkov, O. V.; Saenko, G. V.

    2017-12-01

    The possibility of dissolving frozen crystallization centers in amorphous alloys of the Fe-B system is considered by means of thermodynamic calculations. This can in turn improve the thermal stability of an amorphous alloy. The effect isothermal annealing has on the thermal stability of multicomponent amorphous alloys based on iron is investigated via the highly sensitive dilatometric technique, measurements of microsolidity, and electron microscopic investigations. The annealing temperature is determined empirically on the basis of the theses of the thermodynamic theory of the high temperature stability of multicomponent amorphous alloys, according to which there exists a range of temperatures that is characterized by a negative difference between the chemical potentials of phases in a heterogeneous amorphous matrix-frozen crystallization centers system. The thermodynamic condition of the possible dissolution of frozen crystallization centers is thus met. It is shown that introducing regimes of thermal processing allows us to expand the ranges of the thermal stability of iron-based amorphous alloys by 20-40 K through purifying an amorphous matrix of frozen crystallization centers. This conclusion is proved via electron microscopic investigations.

  17. Investigation of Martensite Formation in Fe Based Alloys During Heating From Boiling Nitrogen Temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Christiansen, Thomas L.; Hansen, Mikkel F.

    2015-01-01

    heating was convincingly demonstrated for all investigated materials by showing heating rate dependent transformation kinetics. Moreover, magnetometry showed that the heating rate influences the fraction of martensite formed during the thermal treatment. The activation energy for thermally activated...

  18. Amorphous Pt@PdCu/CNT Catalyst for Methanol Electrooxidation ...

    African Journals Online (AJOL)

    A multi-walled carbon nanotube-supported, Pt decorated nano-sized amorphous PdCu alloy cores (denoted as Pt@PdCu/CNT) catalyst with lower Pt loading is synthesized via a galvanic displacement reaction. The structure is examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM).

  19. Amorphous Pt@PdCu/CNT Catalyst for Methanol Electrooxidation

    African Journals Online (AJOL)

    NICO

    A multi-walled carbon nanotube-supported, Pt decorated nano-sized amorphous PdCu alloy cores (denoted as Pt@PdCu/CNT) catalyst with lower Pt loading is synthesized via a galvanic displacement reaction. The structure is examined using X-ray diffrac- tion (XRD) and transmission electron microscopy (TEM).

  20. Hydrogen in amorphous silicon

    International Nuclear Information System (INIS)

    Peercy, P.S.

    1980-01-01

    The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

  1. Physics of amorphous metals

    CERN Document Server

    Kovalenko, Nikolai P; Krey, Uwe

    2008-01-01

    The discovery of bulk metallic glasses has led to a large increase in the industrial importance of amorphous metals, and this is expected to continue. This book is the first to describe the theoretical physics of amorphous metals, including the important theoretical development of the last 20 years.The renowned authors stress the universal aspects in their description of the phonon or magnon low-energy excitations in the amorphous metals, e.g. concerning the remarkable consequences of the properties of these excitations for the thermodynamics at low and intermediate temperatures. Tunneling

  2. Amorphization within the tablet

    DEFF Research Database (Denmark)

    Doreth, Maria; Hussein, Murtadha Abdul; Priemel, Petra A.

    2017-01-01

    , the feasibility of microwave irradiation to prepare amorphous solid dispersions (glass solutions) in situ was investigated. Indomethacin (IND) and polyvinylpyrrolidone K12 (PVP) were tableted at a 1:2 (w/w) ratio. In order to study the influence of moisture content and energy input on the degree of amorphization......, tablet formulations were stored at different relative humidity (32, 43 and 54% RH) and subsequently microwaved using nine different power-time combinations up to a maximum energy input of 90 kJ. XRPD results showed that up to 80% (w/w) of IND could be amorphized within the tablet. mDSC measurements...

  3. Torsion-induced magnetoimpedance in nanocrystalline Fe-based wires

    International Nuclear Information System (INIS)

    Santos, J.D.; Olivera, J.; Alvarez, P.; Sanchez, T.; Perez, M.J.; Sanchez, M.L.; Gorria, P.; Hernando, B.

    2007-01-01

    The magnetic field influence on the real and imaginary parts of axial-diagonal (ζ zz ) and off-diagonal (ζ φz ) components of the surface magnetoimpedance (MI) tensor has been studied in amorphous and nanocrystalline Fe 73.5 Si 13.5 B 9 Cu 1 Nb 3 wires. Twisted and untwisted wires were annealed at a temperature near to that of primary crystallization. The MI response has been measured at 1MHz and 5mA rms drive current in all the samples. Even though the higher values for both components of the MI tensor are achieved for the untwisted annealed wire, the most interesting features are observed in the torsion annealed wire

  4. Solid state amorphization in the Al-Fe binary system during high energy milling

    Energy Technology Data Exchange (ETDEWEB)

    Urban, P., E-mail: purban@us.es; Montes, J. M.; Cintas, J. [University of Seville, Department of Mechanical and Materials Engineering, ETSI, Camino de los Descubrimientos s/n, Seville, 41092 (Spain); Cuevas, F. G., E-mail: fgcuevas@dqcm.uhu.es [University of Huelva, Department of Chemistry and Materials Science, ETSI, Campus La Rábida, Carretera Palos s/n, Palos de la Frontera, Huelva, 21819 (Spain)

    2013-12-16

    In the present study, mechanical alloying (MA) of Al75Fe25 elemental powders mixture was carried out in argon atmosphere, using a high energy attritor ball mill. The microstructure of the milled products at different stages of milling was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results showed that the amorphous phase content increased by increasing the milling time, and after 50 hours the amorphization process became complete. Heating the samples resulted in the crystallization of the synthesized amorphous alloys and the appearance of the equilibrium intermetallic compounds Al{sub 5}Fe{sub 2}.

  5. The fluctuation field and anomalous magnetic viscosity in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Collocott, S.J. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)], E-mail: stephen.collocott@csiro.au; Dunlop, J.B. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)

    2008-08-15

    The fluctuation field, H{sub f}, is a useful parameter for characterising any ferromagnetic material that displays hysteresis, as it is a measure of the thermally activated rate processes that govern magnetisation reversals. Anomalous magnetic viscosity, i.e. nonmonotonic behaviour of the time dependent magnetisation, where the magnetisation is seen to increase, reach a peak, and then decrease, has been observed on both the upper and lower branches of minor loops or recoil curves in some ferromagnetic materials. Parameters relevant to the Preisach model are discussed as to their usefulness in predicting anomalous magnetic viscosity in ferromagnetic materials. This is done with reference to measurements of H{sub f} and the time dependent magnetisation in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}.

  6. Wear and Corrosion Resistance of Fe Based Coatings by HVOF Sprayed on Gray Cast-Iron for Automotive Application

    Directory of Open Access Journals (Sweden)

    M.S. Priyan

    2014-12-01

    Full Text Available In this study, commercially available FeSiNiCr and FeBCr alloy powders were designed with suitable compositions, gas atomized and then coated on gray cast-iron substrate. The microstructures of the feed stock Fe based alloy powders and the coatings were investigated by means of optical microscopy (OM, X-Ray diffraction (XRD, Thermogravimetric analysis (TGA and Scanning Electron Microscopy (SEM. In the present study, both the coating materials experienced two-body wear mechanisms. The results showed that for loads of 0.05 N, 0.1 N and 0.2 N, the wear resistance of FeBCr coating was less than FeSiNiCr by 44 %, 40 % and 31 %, respectively. The results indicated that the coated substrates exhibited lower corrosion current densities and lower corrosion rates, when placed in 20 wt.% H2SO4 solutions. In addition, the use of optimal spraying parameters/conditions gave improvements to the corrosion resistance of the substrates that had been treated with the crystalline coating.

  7. Metastable superconducting alloys

    International Nuclear Information System (INIS)

    Johnson, W.L.

    1978-07-01

    The study of metastable metals and alloys has become one of the principal activities of specialists working in the field of superconducting materials. Metastable crystalline superconductors such as the A15-type materials have been given much attention. Non-crystalline superconductors were first studied over twenty years ago by Buckel and Hilsch using the technique of thin film evaporation on a cryogenic substrate. More recently, melt-quenching, sputtering, and ion implantation techniques have been employed to produce a variety of amorphous superconductors. The present article presents a brief review of experimental results and a survey of current work on these materials. The systematics of superconductivity in non-crystalline metals and alloys are described along with an analysis of the microscopic parameters which underlie the observed trends. The unique properties of these superconductors which arise from the high degree of structural disorder in the amorphous state are emphasized

  8. Effect of Nano-Y2O3 on Microstructure and Crack Formation in Laser Direct-Deposited In Situ Particle-Reinforced Fe-Based Coatings

    Science.gov (United States)

    Yin, Guili; Chen, Suiyuan; Liu, Yuanyuan; Liang, Jing; Liu, Changsheng; Kuang, Zheng

    2018-03-01

    In situ hard-particle-reinforced Fe-based composite coatings were prepared on Q235 steel substrates by direct laser deposition using Fe-based alloy powders containing 2 wt.% B, 3 wt.% Si and 1-3 wt.% nano-Y2O3. The microstructures, phase compositions, hardnesses and wear resistances of the deposited coatings with different nano-Y2O3 contents were studied using metallographic microscopy, scanning electron microscopy, x-ray diffraction, transmission electron microscopy, microhardness tests and pin-on-disk abrasion tests (MMW-1A), respectively. The results showed that the appropriate addition of Y2O3 played a role in grain refinement and in decreasing the number of brittle phases and impurity elements in the grain boundaries. Consequently, the number of cracks in the laser-deposited coating also decreased. The Fe-based composite coatings were mainly composed of α-Fe, γ-Fe and in situ-produced reinforced particle phases, such as Cr23C6, Cr7C3, (Cr, Fe)7C3, Fe2B, and CrFeB. When the content of nano-Y2O3 was 2 wt.%, a Fe-based composite coating with a thickness of 4 mm that was free of cracks was obtained, and its surface hardness reached 650HV. Moreover, the wear resistance of the coating with 2 wt.% nano-Y2O3 was the best among the samples studied. The presence of nano-Y2O3 increased the solubility of Cr and Si in the solid solution, which eliminated the residual austenite region, and as a result, the phase transformation from γ-Fe to α-Fe was restrained and the transformation stress was also limited, thereby decreasing the probability of cracks in the coatings.

  9. Microstructure and Properties of Plasma-Nitrided Fe-Based Superalloy Fe-25Ni-15Cr

    Science.gov (United States)

    Xu, Xiaolei; Yu, Zhiwei; Hou, Caiyun; Song, Weixiu; Wang, Yingzhu

    2017-07-01

    Fe-based superalloy Fe-25Ni-15Cr was plasma nitrided at a low temperature of 723 K (450 °C). The nitrided layer was characterized by optical microscopy (OPM) and scanning electron microscopy (SEM) and X-ray diffraction (XRD) through stepwise mechanical polishing and transmission electron microscopy (TEM). The results indicated that the double expanded austenite ( γ N1 and γ N2) was developed on the nitrided surface. Energy-dispersive X-ray spectrum (EDS) revealed that separate expanded austenite layers with distinctly different nitrogen contents occurred: high (18.98 to 11.49 at. pct) in the surface layer and low (5.87 to 5.32 at. pct) in the subsurface. XRD analysis indicated that large lattice expansion and distortion relative to the untreated austenite of an idea face-centered-cubic (fcc) structure occurred on the γ N1, but low expansion and less distortion on the γ N2. No obvious lattice distortion on the γ N1 was determined by calculating its electron diffraction pattern (EDP), except for detectable lattice expansion. Inconformity between XRD and EDP results suggested that the high compressive residual stress in the γ N1 was mainly responsible for the lattice distortion of the γ N1. TEM indicated that the γ N1 layer exhibited the monotonous contrast characteristic of an amorphous phase contrast to some extent, and corresponding EDP showed a strong diffuse scattering effect. It was suggested that the pre-precipitation took place in the γ N1 in the form of strongly bonded Cr-N clusters or pairs. Decomposition of the γ N1 into CrN and γ occurred at the grain boundaries, and the orientation of both phases remained cubic and cubic relationship, i.e., the planes and the directions with identical Miller indices in both phases were parallel. The nitrided surface was found to have significantly improved wear resistance. Further, the nitrided surface showed no adverse effect in the corrosion resistance but slight improvement in the 3.5 pct NaCl solution.

  10. Amorphous selenium based detectors for medical imaging applications

    Science.gov (United States)

    Mandal, Krishna C.; Kang, Sung H.; Choi, Michael; Jellison, Gerald E., Jr.

    2006-08-01

    We have developed and characterized large volume amorphous (a-) selenium (Se) stabilized alloys for room temperature medical imaging devices and high-energy physics detectors. The synthesis and preparation of well-defined and high quality a-Se (B, As, Cl) alloy materials have been conducted using a specially designed alloying reactor at EIC and installed in an argon atmosphere glove box. The alloy composition has been precisely controlled and optimized to ensure good device performance. The synthesis of large volume boron (B) doped (natural and isotopic 10B) a-Se (As, Cl) alloys has been carried out by thoroughly mixing vacuum distilled and zone-refined (ZR) Se with previously synthesized Se-As master alloys, Se-Cl master alloys and B. The synthesized a-Se (B, As, Cl) alloys have been characterized by x-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infra-red spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectroscopy (ICP-MS), and detector testing. The a- Se alloys have shown high promise for x-ray detectors with its high dark resistivity (10 10-10 13 Ωcm), good charge transport properties, and cost-effective large area scalability. Details of various steps about detector fabrication and testing of these imaging devices are also presented.

  11. Magnetic alloys with vanishing anisotropies

    International Nuclear Information System (INIS)

    Couderchon, G.

    1991-01-01

    Co-based amorphous alloys and 80 Ni Permalloys have vanishingly-low anisotropies and show the highest permeabilities and lowest losses among commercial magnetic materials. In spit of their different atomic arrangements, these two types of material show close similarities in domain structure and in their temperature and frequency behavior. Information is also given concerning material technology and applications. (orig.)

  12. 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

  13. Structural amorphous steels

    International Nuclear Information System (INIS)

    Lu, Z.P.; Liu, C.T.; Porter, W.D.; Thompson, J.R.

    2004-01-01

    Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist's dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed

  14. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings: SAM HPCRM Program ? FY04 Annual Report ? Rev. 0 - DARPA DSO & DOE OCRWM Co-Sponsored Advanced Materials Program

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Haslam, J; Wong, F; Ji, S; Day, S; Branagan, D; Marshall, M; Meacham, B; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Weaver, D; Aprigliano, L; Kohler, L; Bayles, R; Lemieux, E; Wolejsza, T; Martin, F; Yang, N; Lucadamo, G; Perepezko, J; Hildal, K; Kaufman, L; Heuer, A; Ernst, F; Michal, G; Kahn, H; Lavernia, E

    2007-09-19

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an 'integral drip shield' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent.

  15. New amorphous alloy with high glass forming ability on the Cu-Zr-Al-Gd system; Desenvolvimento de nova liga com estrutura amorfa no sistema Cu-Zr-Al-Gd

    Energy Technology Data Exchange (ETDEWEB)

    Mazzer, E.M.; Aliaga, L.C.R.; Bolfarini, C.; Botta Filho, W.J.; Kiminami, C.S., E-mail: eric_mazzer@hotmail.co [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The prediction of the Glass Forming Ability (GFA) in metallic alloys is usually performed by empirical or semi-empirical criteria in binary or ternary systems. For multi-component systems with more than three elements, the criteria or models become extremely complex making it impractical. In this paper we present the results on the GFA prediction of the Cu-Zr-Al-Gd alloys, where compositions had been selected for the synergy of the topological instability and electronegativity criteria which was increased by the average radio criterion for the quaternary system. Alloys were prepared and processed by arc-meting and die casting techniques. Characterization was made by x-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques. It was concluded that Cu{sub 39,2}Zr{sub 49}Al{sub 9}, {sub 80}Gd{sub 2} alloy presents high thermal stability expressed by great supercooled liquid region upper to 76 deg C. (author)

  16. Effects of temperature dependent pre-amorphization implantation on NiPt silicide formation and thermal stability on Si(100)

    International Nuclear Information System (INIS)

    Ozcan, Ahmet S.; Wall, Donald; Jordan-Sweet, Jean; Lavoie, Christian

    2013-01-01

    Using temperature controlled Si and C ion implantation, we studied the effects of pre-amorphization implantation on NiPt alloy silicide phase formation. In situ synchrotron x-ray diffraction and resistance measurements were used to monitor phase and morphology evolution in silicide films. Results show that substrate amorphization strongly modulate the nucleation of silicide phases, regardless of implant species. However, morphological stability of the thin films is mainly enhanced by C addition, independently of the amorphization depth.

  17. Properties and applications of ion-implanted alloys

    International Nuclear Information System (INIS)

    Myers, S.M.

    1979-01-01

    Ion implantation is a controlled and versatile means for near-surface alloying of metals. Supersaturated solutions, metastable compounds, amorphous phases, and equilibrium alloys have been produced. Uses include the investigation of new metastable phases, characterization of alloying reactions occurring in conventional materials, and improvement of surface properties such as hardness, wear, and corrosion. A brief review is given of the physical processes occurring during ion implantation, the types of alloys which result, and representative applications

  18. Traveling cluster approximation for uncorrelated amorphous systems

    International Nuclear Information System (INIS)

    Kaplan, T.; Sen, A.K.; Gray, L.J.; Mills, R.

    1985-01-01

    In this paper, the authors apply the TCA concepts to spatially disordered, uncorrelated systems (e.g., fluids or amorphous metals without short-range order). This is the first approximation scheme for amorphous systems that takes cluster effects into account while preserving the Herglotz property for any amount of disorder. They have performed some computer calculations for the pair TCA, for the model case of delta-function potentials on a one-dimensional random chain. These results are compared with exact calculations (which, in principle, taken into account all cluster effects) and with the CPA, which is the single-site TCA. The density of states for the pair TCA clearly shows some improvement over the CPA, and yet, apparently, the pair approximation distorts some of the features of the exact results. They conclude that the effects of large clusters are much more important in an uncorrelated liquid metal than in a substitutional alloy. As a result, the pair TCA, which does quite a nice job for alloys, is not adequate for the liquid. Larger clusters must be treated exactly, and therefore an n-TCA with n > 2 must be used

  19. Mechanical characteristics of Fe-based coating obtained by nanoindentation

    International Nuclear Information System (INIS)

    Li Huayi; Li Guolu; Wang Haidou; Xu Binshi

    2011-01-01

    Research highlights: → AFM combined with O and P method was put forward to investigate materials of pile-up. → Properties obtained by G and S and new proposed methods showed the same distribution. → Both hardness and elastic modulus showed certain surface roughness dependence. → Elastic modulus obtained by AFM combined with O and P method was insensitive to RMS. - Abstract: In this study, clad layers of iron-based alloy with a nature of self-fluxing were melted on low carbon steel by plasma cladding process. Nanoindentation with atomic force microscopy (AFM) has been used to investigate the mechanical properties of the coating. Hardness and elastic modulus at ultra-low loads were first determined using the method proposed by Giannakopoulos and Suresh (G and S method). The true contact area and mechanical properties were then determined using atomic force microscopy (AFM) combined with the Oliver and Pharr method (new proposed method) as the correction group. The mechanical properties calculated by the two methods showed the same distribution while had deviation in specific values. The effect of surface roughness to the calculated mechanical properties was investigated. Both hardness and elastic modulus were found to exhibit certain surface roughness dependence. When root mean square (RMS) roughness ranged from 2.2 nm to 4.4 nm, hardness calculated by both the methods increased obviously and reached maximums around 4.1 nm. Elastic modulus calculated by G and S method at different RMS showed the same distribution with that of hardness, while reduced elastic modulus obtained by AFM was insensitive to the range of RMS.

  20. Glass nanoimprint using amorphous Ni-P mold etched by focused-ion beam

    International Nuclear Information System (INIS)

    Mekaru, Harutaka; Kitadani, Takeshi; Yamashita, Michiru; Takahashi, Masaharu

    2007-01-01

    The authors succeeded in glass-nanoimprint lithography of micropatterns and nanopatterns using an amorphous Ni-P alloy mold. Glasslike carbon has been used as a mold material to mold not only Pyrex glass but also quartz, because it is still stable at a temperature of 1650 deg. C. However, it is difficult to process glasslike carbon substrates into arbitrary shapes by machining. They thought that amorphous Ni-P alloy could be used as a mold material for industrial glass molding. If Ni is electroless plated when mixed with suitable amount of P on a Si wafer, the Ni-P alloy layer becomes amorphous. An appropriate ratio of Ni and P was determined by the results of x-ray-diffraction measurements. The optimized composition ratio of Ni-P was Ni:P=92:8 wt %. Moreover, line and space patterns and dot arrays with linewidths of as little as 500 nm were etched on the mold using focused-ion beam (FIB) and the processing accuracy for the amorphous Ni-P layer was compared with that for the pure Ni layer. The result was that patterns of 500 nm width were etched to a depth of 2 μm on an amorphous Ni-P alloy mold and the processed surfaces were smooth. In contrast, in the case of the pure Ni layer, the processing line was notched and the sidewalls were very rough. The crystal grain seems to hinder the processing of the nanopattern. After FIB etching, the amorphous Ni-P alloy was thermally treated at 400 deg. C to improve the hardness. Finally, line and space patterns and dot arrays on the amorphous Ni-P alloy mold were nanoimprinted on Pyrex glass using a glass-nanoimprint system (ASHE0201) that National Institute of Advanced Industrial Science and Technology developed

  1. Thermal stability of high temperature structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, C.E.; Rasefske, R.K.; Castagna, A. [Lockheed Martin Corp., Schenectady, NY (United States)

    1999-03-01

    High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.

  2. Design and fabrication of a mechanical alloying system for preparing intermetallic, nanocrystalline, amorphous and quasicrystalline compounds; Diseno y fabricacion de un sistema de aleado mecanico para preparar compuestos intermetalicos, nanocristalinos, amorfos y cuasicristalinos

    Energy Technology Data Exchange (ETDEWEB)

    Bonifacio M, J.; Iturbe G, J.L.; Castaneda J, G. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    In this work a grinding system was designed and fabricated which allowed to improve the operation conditions in time, frequency, temperature and selection of the grinding media and that allow the contamination decrease of the compounds. By means of this method of mechanical alloying new metallic compounds can be produced, starting from elemental powders, with fine and controlled microstructures. These compounds prepared by this method are going to be used as materials for the hydrogen storage. (Author)

  3. Continuous stress annealing of amorphous ribbons for strain sensing applications

    Czech Academy of Sciences Publication Activity Database

    Kraus, Luděk; Bydžovský, J.; Švec, P.

    2003-01-01

    Roč. 106, - (2003), s. 117-120 ISSN 0924-4247. [European Magnetic Sensors and Actuators Conference EMSA 2002 /4./. Athény, 03.07.2002-05.07.2002] R&D Projects: GA MŠk ME 355 Institutional research plan: CEZ:AV0Z1010914 Keywords : strain sensors * amorphous alloys * magnetic anisotropy * magnetoelastic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.422, year: 2003

  4. Evaluation of Amorphous Ribbon Reinforced Resin Matrix Composites.

    Science.gov (United States)

    1980-04-30

    magnetic properties offered by the ribbons may result in some unique composite applications. UNiLASSMI lED SECURITY CLASIFICATION OF T--- PAGE(Wfa DOMa...presented in Table 2. Excellent transverse to longitudinal property ratios are demonstrated in these data. The cold rolled carbon steel / epoxy system...reinforcements. Amorphous metals have specific strengths significantly higher than that offered by cold rolled steel alloys. The cold rolled steels have an

  5. Study of Sn100-xMnx amorphous system by 119Sn Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Drago, V.

    1986-01-01

    Thin films of Sn 100-x Mn x amorphous alloys with large range of concentrations were procedure by vapor condensation technique on substrates at temperatures near to liquid helium. The magnetic and paramagnetic hyperfine spectra, and the ordering temperatures were measured by 119 Sn Moessbauer effect. The electrical resistivity was used for characterizing the amorphous state. All the measurements were done 'in situ'. A magnetic phase diagram is proposed. (M.C.K.) [pt

  6. Magnetoresistance of amorphous CuZr: weak localization in a three dimensional system

    International Nuclear Information System (INIS)

    Bieri, J.B.; Fert, A.; Creuzet, G.

    1984-01-01

    Observations of anomalous magnetoresistance in amorphous CuZr at low temperature are reported. The magnetoresistance can be precisely accounted for in theoretical models of localization for 3-dimensional metallic systems in the presence of strong spin-orbit interactions (with a significant additional contribution from the quenching of superconducting fluctuations at the lowest temperatures). Magnetoresistance measurements on various other systems show that such 3-dimensional localization effects are very generally observed in amorphous alloys. (author)

  7. Chemically prepared amorphous Fe-B particles: Influence of pH on the composition

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, Steen

    1990-01-01

    Fe-B alloys have been prepared by reduction of Fe ions by NaBH4 in aqueous solutions. The boron content was found to vary with pH. For pH between 5 and 7, amorphous Fe72B28 powders were produced. Outside this pH range also alpha-Fe appeared in the samples. However, for pH=8 amorphous Fe86B14...

  8. The Stabilization of Amorphous Zopiclone in an Amorphous Solid Dispersion.

    Science.gov (United States)

    Milne, Marnus; Liebenberg, Wilna; Aucamp, Marique

    2015-10-01

    Zopiclone is a poorly soluble psychotherapeutic agent. The aim of this study was to prepare and characterize an amorphous form of zopiclone as well as the characterization and performance of a stable amorphous solid dispersion. The amorphous form was prepared by the well-known method of quench-cooling of the melt. The solid dispersion was prepared by a solvent evaporation method of zopiclone, polyvinylpyrrolidone-25 (PVP-25), and methanol, followed by freeze-drying. The physico-chemical properties and stability of amorphous zopiclone and the solid dispersion was studied using differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), hot-stage microscopy (HSM), X-ray diffractometry (XRD), solubility, and dissolution studies. The zopiclone amorphous solid-state form was determined to be a fragile glass; it was concluded that the stability of the amorphous form is influenced by both temperature and water. Exposure of amorphous zopiclone to moisture results in rapid transformation of the amorphous form to the crystalline dihydrated form. In comparison, the amorphous solid dispersion proved to be more stable with increased aqueous solubility.

  9. Replication of surface features from a master model to an amorphous metallic article

    Science.gov (United States)

    Johnson, William L.; Bakke, Eric; Peker, Atakan

    1999-01-01

    The surface features of an article are replicated by preparing a master model having a preselected surface feature thereon which is to be replicated, and replicating the preselected surface feature of the master model. The replication is accomplished by providing a piece of a bulk-solidifying amorphous metallic alloy, contacting the piece of the bulk-solidifying amorphous metallic alloy to the surface of the master model at an elevated replication temperature to transfer a negative copy of the preselected surface feature of the master model to the piece, and separating the piece having the negative copy of the preselected surface feature from the master model.

  10. Superconductivity in SnO: A Nonmagnetic Analog to Fe-Based Superconductors?

    DEFF Research Database (Denmark)

    Forthaus, M. K.; Sengupta, K.; Heyer, O.

    2010-01-01

    and superconductivity disappears for p≳16  GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc...

  11. FY05 HPCRM Annual Report: High-Performance Corrosion-Resistant Iron-Based Amorphous Metal Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Choi, J; Haslam, J; Day, S; Yang, N; Headley, T; Lucadamo, G; Yio, J; Chames, J; Gardea, A; Clift, M; Blue, G; Peters, W; Rivard, J; Harper, D; Swank, D; Bayles, R; Lemieux, E; Brown, R; Wolejsza, T; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Lavernia, E; Schoenung, J; Ajdelsztajn, L; Dannenberg, J; Graeve, O; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Boudreau, J

    2007-09-20

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Two Fe-based amorphous metal formulations have been found that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22, based on breakdown potential and corrosion rate. Both Cr and Mo provide corrosion resistance, B enables glass formation, and Y lowers critical cooling rate (CCR). SAM1651 has yttrium added, and has a nominal critical cooling rate of only 80 Kelvin per second, while SAM2X7 (similar to SAM2X5) has no yttrium, and a relatively high critical cooling rate of 610 Kelvin per second. Both amorphous metal formulations have strengths and weaknesses. SAM1651 (yttrium added) has a low critical cooling rate (CCR), which enables it to be rendered as a completely amorphous thermal spray coating. Unfortunately, it is relatively difficult to atomize, with powders being irregular in shape. This causes the powder to be difficult to pneumatically convey during thermal spray deposition. Gas atomized SAM1651 powder has required cryogenic milling to eliminate irregularities that make flow difficult. SAM2X5 (no yttrium) has a high critical cooling rate, which has caused problems associated with devitrification. SAM2X5 can be gas atomized to produce spherical powders of SAM2X5, which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer

  12. PASSIVATION LAYER STABILITY OF A METALLIC ALLOY WASTE FORM

    International Nuclear Information System (INIS)

    Williamson, M.; Mickalonis, J.; Fisher, D.; Sindelar, R.

    2010-01-01

    Alloy waste form development under the Waste Forms Campaign of the DOE-NE Fuel Cycle Research and Development program includes the process development and characterization of an alloy system to incorporate metal species from the waste streams generated during nuclear fuel recycling. This report describes the tests and results from the FY10 activities to further investigate an Fe-based waste form that uses 300-series stainless steel as the base alloy in an induction furnace melt process to incorporate the waste species from a closed nuclear fuel recycle separations scheme. This report is focused on the initial activities to investigate the formation of oxyhydroxide layer(s) that would be expected to develop on the Fe-based waste form as it corrodes under aqueous repository conditions. Corrosion tests were used to evaluate the stability of the layer(s) that can act as a passivation layer against further corrosion and would affect waste form durability in a disposal environment.

  13. Facile synthesis of monodisperse thermally immiscible Ag–Ni alloy ...

    Indian Academy of Sciences (India)

    Administrator

    amorphous Ag–Ni alloy nanoparticles (ANPs) with mono-disperse distribution. Microscopic and spectroscopic studies confirmed dependence of the alloy composition on size of nanoparticles. In the presence of different ligands such as sodium citrate, polyvinyl alcohol and potassium carbonate a mixture of silver oxide and ...

  14. Phosphorus containing sintered alloys (review)

    International Nuclear Information System (INIS)

    Muchnik, S.V.

    1984-01-01

    Phosphorus additives are considered for their effect on the properties of sintered alloys of different applications: structural, antifriction, friction, magnetic, hard, superhard, heavy etc. Data are presented on compositions and properties of phosphorus-containing materials produced by the powder metallurgy method. Phosphorus is shown to be an effective activator of sintering in some cases. When its concentration in the material is optimal it imparts the material such properties as strength, viscosity, hardness, wear resistance. Problems concerning powder metallurgy of amorphous phosphorus-containing alloys are reported

  15. Corrosion behaviour of amorphous Ti48Cu52, Ti50Cu50 and ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Potentiodynamic polarization studies were carried out on virgin specimens of amorphous alloys. Ti48Cu52, Ti50Cu50 and Ti60Ni40 in 0⋅5 M HNO3, 0⋅5 M H2SO4 and 0⋅5 M NaOH aqueous media at room tem- perature. The value of the corrosion current density (Icorr) was maximum for Ti48Cu52 alloy in all the ...

  16. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  17. Amorphous Gyroscopic Topological Metamaterials

    Science.gov (United States)

    Mitchell, Noah P.; Nash, Lisa M.; Hexner, Daniel; Turner, Ari M.; Irvine, William T. M.

    Mechanical topological metamaterials display striking mechanical responses, such as unidirectional surface modes that are impervious to disorder. This behavior arises from the topology of their vibrational spectra. All examples of topological metamaterials to date are finely-tuned structures such as crystalline lattices or jammed packings. Here, we present robust recipes for building amorphous topological metamaterials with arbitrary underlying structure and no long-range order. Using interacting gyroscopes as a model system, we demonstrate through experiment, simulation, and theoretical methods that the local geometry and interactions are sufficient to generate topological mobility gaps, allowing for spatially-resolved, real-space calculations of the Chern number. The robustness of our approach enables the design and self-assembly of non-crystalline materials with protected, unidirectional waveguides on the micro and macro scale.

  18. Alloy materials

    Energy Technology Data Exchange (ETDEWEB)

    Hans Thieme, Cornelis Leo (Westborough, MA); Thompson, Elliott D. (Coventry, RI); Fritzemeier, Leslie G. (Acton, MA); Cameron, Robert D. (Franklin, MA); Siegal, Edward J. (Malden, MA)

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  19. 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.)

  20. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Escribano, J. A.; Ferrari, B.; Alvaredo, P.; Gordo, E.; Sanchez-Herencia, A. J.

    2013-07-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  1. Structure, magnetic order and excitations in the 245 family of Fe-based superconductors

    OpenAIRE

    Bao, Wei

    2014-01-01

    Elastic neutron scattering simultaneously probes both the crystal structure and magnetic order in a material. Inelastic neutron scattering measures phonons and magnetic excitations. Here, we review the average composition, crystal structure and magnetic order in the 245 family of Fe-based superconductors and in related insulating compounds from neutron diffraction works. A three-dimensional phase-diagram summarizes various structural, magnetic and electronic properties as a function of the sa...

  2. Amorphous surface layers in Ti-implanted Fe

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, J.A.; Follstaedt, D.M.; Picraux, S.T.

    1979-01-01

    Implanting Ti into high-purity Fe results in an amorphous surface layer which is composed of not only Fe and Ti, but also C. Implantations were carried out at room temperature over the energy range 90 to 190 keV and fluence range 1 to 2 x 10/sup 16/ at/cm/sup 2/. The Ti-implanted Fe system has been characterized using transmission electron microscopy (TEM), ion backscattering and channeling analysis, and (d,p) nuclear reaction analysis. The amorphous layer was observed to form at the surface and grow inward with increasing Ti fluence. For an implant of 1 x 10/sup 17/ Ti/cm/sup 2/ at 180 keV the layer thickness was 150 A, while the measured range of the implanted Ti was approx. 550 A. This difference is due to the incorporation of C into the amorphous alloy by C being deposited on the surface during implantation and subsequently diffusing into the solid. Our results indicate that C is an essential constituent of the amorphous phase for Ti concentrations less than or equal to 10 at. %. For the 1 x 10/sup 17/ Ti/cm/sup 2/ implant, the concentration of C in the amorphous phase was approx. 25 at. %, while that of Ti was only approx. 3 at. %. A higher fluence implant of 2 x 10/sup 17/ Ti/cm/sup 2/ produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %.

  3. On amorphization and nanocomposite formation in Al–Ni–Ti system ...

    Indian Academy of Sciences (India)

    Abstract. Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through controlled devitrification. The amor- phous forming composition range of ternary Al–Ni–Ti system was calculated using the extended Miedema's semi-empirical model. Eleven ...

  4. Long-time stability of structure in Fe-B amorphous ribbons

    NARCIS (Netherlands)

    Csach, K; Miskuf, J; Bengus, VZ; Tabachnikova, ED; Ocelik, Vaclav

    2002-01-01

    The mechanical properties of amorphous metallic alloys ribbons with a nominal composition Fe1-xBx (x =14, 16, 17 and 20 at.%) leave been investigated. The samples were failured after manufacturing and 10 years keeping at room temperature. The fracture stress decreases after keeping on 600 MPa for

  5. Industrial wastewater advanced treatment via catalytic ozonation with an Fe-based catalyst.

    Science.gov (United States)

    Li, Xufang; Chen, Weiyu; Ma, Luming; Wang, Hongwu; Fan, Jinhong

    2018-03-01

    An Fe-based catalyst was used as a heterogeneous catalyst for the ozonation of industrial wastewater, and key operational parameters (pH and catalyst dosage) were studied. The results indicated that the Fe-based catalyst significantly improved the mineralization of organic pollutants in wastewater. TOC (total organic carbon) removal was high, at 78.7%, with a catalyst concentration of 200 g/L, but only 31.6% with ozonation alone. The Fe-based catalyst significantly promoted ozone decomposition by 70% in aqueous solution. Hydroxyl radicals (·OH) were confirmed to be existed directly via EPR (electron paramagnetic resonance) experiments, and ·OH were verified to account for about 34.4% of TOC removal with NaHCO 3 as a radical scavenger. Through characterization by SEM-EDS (field emission scanning electron microscope with energy-dispersive spectrometer), XRD (X-ray powder diffraction) and XPS (X-ray photoelectron spectroscopy), it was deduced that FeOOH on the surface of the catalyst was the dominant contributor to the catalytic efficiency. The catalyst was certified as having good stability and excellent reusability based on 50 successive operations and could be used as a filler simultaneously. Thereby, it is a promising catalyst for practical industrial wastewater advanced treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Magnetoresistance in amorphous NdFeB/FeB compositionally modulated multilayers

    International Nuclear Information System (INIS)

    Peral, G.; Briones, F.; Vicent, J.L.

    1991-01-01

    Resistance measurements have been done in amorphous Nd 12 Fe 80 B 8 sputtered films and in amorphous sputtered Nd 26 Fe 68 B 6 /Fe 92 B 8 multilayers between 6 and 150 K with applied magnetic field parallel (LMR) and perpendicular (TMR) up to 7 T. The samples were grown by dc triode sputtering, with nominal unequal (2:1) layer thicknesses. The layered character of the samples have been tested by x-ray diffraction. Longitudinal magnetoresistance (LMR) is positive and transverse magnetoresistance (TMR) is negative. The magnetoresistance values are higher than in amorphous ferromagnets, and multilayering of these alloys produces much larger magnetoresistance values than either alloy alone and there is a strong dependence on the multilayer wavelength. The MR shows a weak temperature dependence in the temperature interval that was investigated

  7. Ferrofluids based on Co-Fe-Si-B amorphous nanoparticles

    Science.gov (United States)

    Wang, Tianqi; Bian, Xiufang; Yang, Chuncheng; Zhao, Shuchun; Yu, Mengchun

    2017-03-01

    Magnetic Co-Fe-Si-B amorphous nanoparticles were successfully synthesized by chemical reduction method. ICP, XRD, DSC, and TEM were used to investigate the composition, structure and morphology of Co-Fe-Si-B samples. The results show that the Co-Fe-Si-B samples are amorphous, which consist of nearly spherical nanoparticles with an average particle size about 23 nm. VSM results manifest that the saturation magnetization (Ms) of Co-Fe-Si-B samples ranges from 46.37 to 62.89 emu/g. Two kinds of ferrofluids (FFs) were prepared by dispersing Co-Fe-Si-B amorphous nanoparticles and CoFe2O4 nanoparticles in kerosene and silicone oil, respectively. The magnetic properties, stability and viscosity of the FFs were investigated. The FFs with Co-Fe-Si-B samples have a higher Ms and lower coercivity (Hc) than FFs with CoFe2O4 sample. Under magnetic field, the silicone oil-based FFs exhibit high stability. The viscosity of FFs under different applied magnetic fields was measured by a rotational viscometer, indicating that FFs with Co-Fe-Si-B particles present relative strong response to an external magnetic field. The metal-boride amorphous alloy nanoparticles have potential applications in the preparation of magnetic fluids with good stability and good magnetoviscous properties.

  8. Characterization of the hidden glass transition of amorphous cyclomaltoheptaose.

    Science.gov (United States)

    Tabary, Nicolas; Mahieu, Aurélien; Willart, Jean-François; Dudognon, Emeline; Danède, Florence; Descamps, Marc; Bacquet, Maryse; Martel, Bernard

    2011-10-18

    An amorphous solid of cyclomaltoheptaose (β-cyclodextrin, β-CD) was formed by milling its crystalline form using a high-energy planetary mill at room temperature. The glass transition of this amorphous solid was found to occur above the thermal degradation point of the material preventing its direct observation and thus its full characterization. The corresponding glass transition temperature (T(g)) and the ΔC(p) at T(g) have, however, been estimated by extrapolation of T(g) and ΔC(p) of closely related amorphous compounds. These compounds include methylated β-CD with different degrees of substitution and molecular alloys obtained by co-milling β-CD and methylated β-CD (DS 1.8) at different ratios. The physical characterization of the amorphous states have been performed by powder X-ray diffraction and differential scanning calorimetry, while the chemical integrity of β-CD upon milling was checked by NMR spectroscopy and mass spectrometry. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Structural origin of resistance drift in amorphous GeTe

    Science.gov (United States)

    Zipoli, Federico; Krebs, Daniel; Curioni, Alessandro

    2016-03-01

    We used atomistic simulations to study the origin of the change of resistance over time in the amorphous phase of GeTe, a prototypical phase-change material (PCM). Understanding the cause of resistance drift is one of the biggest challenges to improve multilevel storage technology. For this purpose, we generated amorphous structures via classical molecular-dynamics simulations under conditions as close as possible to the experimental operating ones of such memory devices. Moreover, we used the replica-exchange technique to generate structures comparable with those obtained in the experiment after long annealing that show an increase of resistance. This framework allowed us to overcome the main limitation of previous simulations, based on density-functional theory, that suffered from being computationally too expensive therefore limited to the nanosecond time scale. We found that resistance drift is caused by consumption of Ge atom clusters in which the coordination of at least one Ge atom differs from that of the crystalline phase and by removal of stretched bonds in the amorphous network, leading to a shift of the Fermi level towards the middle of the band gap. These results show that one route to design better memory devices based on current chalcogenide alloys is to reduce the resistance drift by increasing the rigidity of the amorphous network.

  10. Kinetically Controlled Two-Step Amorphization and Amorphous-Amorphous Transition in Ice

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chuanlong; Yong, Xue; Tse, John S.; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kenney-Benson, Curtis; Shen, Guoyin

    2017-09-01

    We report the results of in situ structural characterization of the amorphization of crystalline ice Ih under compression and the relaxation of high-density amorphous (HDA) ice under decompression at temperatures between 96 and 160 K by synchrotron x-ray diffraction. The results show that ice Ih transforms to an intermediate crystalline phase at 100 K prior to complete amorphization, which is supported by molecular dynamics calculations. The phase transition pathways show clear temperature dependence: direct amorphization without an intermediate phase is observed at 133 K, while at 145 K a direct Ih-to-IX transformation is observed; decompression of HDA shows a transition to low-density amorphous ice at 96 K and ~ 1 Pa , to ice Ic at 135 K and to ice IX at 145 K. These observations show that the amorphization of compressed ice Ih and the recrystallization of decompressed HDA are strongly dependent on temperature and controlled by kinetic barriers. Pressure-induced amorphous ice is an intermediate state in the phase transition from the connected H-bond water network in low pressure ices to the independent and interpenetrating H-bond network of high-pressure ices.

  11. Structural morphology of amorphous conducting carbon film

    Indian Academy of Sciences (India)

    Unknown

    been found to be having a lot of technological applica- tions. The properties of these amorphous carbons sensi- tively depend on the relative concentration of sp3 and sp2 hybridized carbons. The resulting amorphous materials are variously referred to as tetrahedral amorphous carbon. (ta-C), amorphous carbon (a-C), ...

  12. Amorphous drugs and dosage forms

    DEFF Research Database (Denmark)

    Grohganz, Holger; Löbmann, K.; Priemel, P.

    2013-01-01

    The transformation to an amorphous form is one of the most promising approaches to address the low solubility of drug compounds, the latter being an increasing challenge in the development of new drug candidates. However, amorphous forms are high energy solids and tend to recry stallize. New...... formulation principles are needed to ensure the stability of amorphous drug forms. The formation of solid dispersions is still the most investigated approach, but additional approaches are desirable to overcome the shortcomings of solid dispersions. Spatial separation by either coating or the use of micro......-containers has shown potential to prevent or delay recrystallization. Another recent approach is the formation of co-amorphous mixtures between either two drugs or one drug and one low molecular weight excipient. Molecular interactions between the two molecules provide an energy barrier that has to be overcome...

  13. Rapid solidification of Ni50Nb28Zr22 glass former alloy through suction-casting

    International Nuclear Information System (INIS)

    Miyamoto, M.I.; Santos, F.S.; Bolfarini, C.; Botta Filho, W.J.; Kiminami, C.S.

    2010-01-01

    To select new alloys with high glass forming ability (GFA) to present amorphous structure in millimeter scale, several semi-empirical models have been developed. In the present work, a new alloy, Ni 50 Nb 28 Zr 22 d, was designed based on the combination of topological instability lambda (A) criterion and electronegativity difference (Δe). The alloy was rapidly solidified in a bulk wedge sample by cooper mold suction casting in order to investigate its amorphization. The sample was characterized by the combination of scanning electron microscopy (MEV), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). For the minimum thickness of 200 μm analyzed, it was found that the alloy did not show a totally amorphous structure. Factor such as low cooling rate, existence of oxides on the surface of the elements and presence of oxygen in the atmosphere of equipment did not allowed the achievement of higher amorphous thickness. (author)

  14. Diamond amorphization in neutron irradiation

    International Nuclear Information System (INIS)

    Nikolaenko, V.A.; Gordeev, V.G.

    1996-01-01

    The paper presents the results on neutron irradiation of the diamond in a nuclear reactor. It is shown that the neutron irradiation stimulates the diamond transition to the amorphous state. At a temperature below 750 o K the time required for the diamond-graphite transition decreases with decreasing irradiation temperature. On the contrary, in irradiation at higher temperatures the time of diamond conversion into the amorphous state increases with decreasing but always remains shorter than in the absence of irradiation. (author)

  15. Anomalous magnetoresistance in amorphous metals

    International Nuclear Information System (INIS)

    Kuz'menko, V.M.; Vladychkin, A.N.; Mel'nikov, V.I.; Sudovtsev, A.I.

    1984-01-01

    The magnetoresistance of amorphous Bi, Ca, V and Yb films is investigated in fields up to 4 T at low temperatures. For all metals the magnetoresistance is positive, sharply decreases with growth of temperature and depends anomalously on the magnetic field strength. For amorphous superconductors the results agree satisfactorily with the theory of anomalous magnetoresistance in which allowance is made for scattering of electrons by the superconducting fluctuations

  16. Analysis and evaluation for practical application of photovoltaic power generation system. Analysis and evaluation for thin substrate polycrystalline solar cells (alloy-base amorphous materials, PIN layers, strains in the interface, and effects of impurities); Taiyoko hatsuden system jitsuyoka no tame no kaiseki hyoka. Usumaku taiyo denchi jitsuyoka no tame no kaiseki hyoka (gokinkei amorphous zairyo pin kakuso kaimen ni okeru yugami fujunbutsu nado no eikyo)

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, A.; Oeda, H.; Yamasaki, S.; Hata, N.; Kondo, M.; Toshima, Y.; Sakata, I.; Ganguly, G.; Suzuki, A.; Kamei, T.; Okushi, H.; Nonaka, H.; Oda, N.; Katagiri, H.; Ichimura, N.; Kokubu, K.; Nakamura, K.; Sekikawa, T.; Yamanaka, M. [Electrotechnical Laboratory, Tsukuba (Japan)

    1994-12-01

    Described herein are the results of the FY1994 research program for analysis and evaluation for thin film solar cells. The study on quantitative analysis of hydrogen atoms in a plasma determines quantity of hydrogen atoms in the plasma of monosilane diluted with hydrogen. It is found, contrary to expectation, that quantity of hydrogen atoms in the plasma decreases as it is more diluted with hydrogen. The study on light-induced degradation of the thin chlorine-base amorphous silicon films confirms that the plasma CVD method with 20% of dichlorosilane gas added to monosilane gas produces the thin amorphous silicon film 3 times faster than the conventional method. The thin film has essentially the same defect density as the one prepared by the conventional method, showing good photoelectric characteristics. The thin film of chlorinated amorphous silicon has a 1 digit lower defect density than the conventional one of amorphous silicon, as revealed by the accelerated degradation test with irradiated laser light and the constant current method to determine saturated defect density. 3 figs.

  17. Actual possibilities of gas-pressure metallurgy for ecological technological production of new alloys

    International Nuclear Information System (INIS)

    Kolev, Bogomil Velikov

    2003-01-01

    The objective of this study is to present to international technical circles a summary of some basic current scientific and applied results of the author's investigations on absorption and retention of nitrogen (N * ), structure formation of new Fe-based high strength cast alloys. (Original)

  18. Effect of Si additions on thermal stability and the phase transition sequence of sputtered amorphous alumina thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bolvardi, H.; Baben, M. to; Nahif, F.; Music, D., E-mail: music@mch.rwth-aachen.de; Schnabel, V.; Shaha, K. P.; Mráz, S.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Bednarcik, J.; Michalikova, J. [Deutsches Elektronen Synchrotron DESY, FS-PE group, Notkestrasse 85, D-22607 Hamburg (Germany)

    2015-01-14

    Si-alloyed amorphous alumina coatings having a silicon concentration of 0 to 2.7 at. % were deposited by combinatorial reactive pulsed DC magnetron sputtering of Al and Al-Si (90-10 at. %) split segments in Ar/O{sub 2} atmosphere. The effect of Si alloying on thermal stability of the as-deposited amorphous alumina thin films and the phase formation sequence was evaluated by using differential scanning calorimetry and X-ray diffraction. The thermal stability window of the amorphous phase containing 2.7 at. % of Si was increased by more than 100 °C compared to that of the unalloyed phase. A similar retarding effect of Si alloying was also observed for the α-Al{sub 2}O{sub 3} formation temperature, which increased by more than 120 °C. While for the latter retardation, the evidence for the presence of SiO{sub 2} at the grain boundaries was presented previously, this obviously cannot explain the stability enhancement reported here for the amorphous phase. Based on density functional theory molecular dynamics simulations and synchrotron X-ray diffraction experiments for amorphous Al{sub 2}O{sub 3} with and without Si incorporation, we suggest that the experimentally identified enhanced thermal stability of amorphous alumina with addition of Si is due to the formation of shorter and stronger Si–O bonds as compared to Al–O bonds.

  19. Hydrogenated amorphous silicon photonics

    Science.gov (United States)

    Narayanan, Karthik

    2011-12-01

    Silicon Photonics is quickly proving to be a suitable interconnect technology for meeting the future goals of on-chip bandwidth and low power requirements. However, it is not clear how silicon photonics will be integrated into CMOS chips, particularly microprocessors. The issue of integrating photonic circuits into electronic IC fabrication processes to achieve maximum flexibility and minimum complexity and cost is an important one. In order to minimize usage of chip real estate, it will be advantageous to integrate in three-dimensions. Hydrogenated amorphous silicon (a-Si:H) is emerging as a promising material for the 3-D integration of silicon photonics for on-chip optical interconnects. In addition, a-Si:H film can be deposited using CMOS compatible low temperature plasma-enhanced chemical vapor deposition (PECVD) process at any point in the fabrication process allowing maximum flexibility and minimal complexity. In this thesis, we demonstrate a-Si:H as a high performance alternate platform to crystalline silicon, enabling backend integration of optical interconnects in a hybrid photonic-electronic network-on-chip architecture. High quality passive devices are fabricated on a low-loss a-Si:H platform enabling wavelength division multiplexing schemes. We demonstrate a broadband all-optical modulation scheme based on free-carrier absorption effect, which can enable compact electro-optic modulators in a-Si:H. Furthermore, we comprehensively characterize the optical nonlinearities in a-Si:H and observe that a-Si:H exhibits enhanced nonlinearities as compared to crystalline silicon. Based on the enhanced nonlinearities, we demonstrate low-power four-wave mixing in a-Si:H waveguides enabling high speed all-optical devices in an a-Si:H platform. Finally, we demonstrate a novel data encoding scheme using thermal and all-optical tuning of silicon waveguides, increasing the spectral efficiency in an interconnect link.

  20. Corrosion and corrosion-friction properties of plasma cladding wear-resistant layer on Fe-based alloy

    Science.gov (United States)

    Zhang, Dekun; Yu, Ruoqi; Chen, Kai; Yang, Xuehui; Liu, Yuan; Yin, Yan

    2018-02-01

    Plasma cladding technology is used to prepare a plasma cladding gradient wear-resistant layer, and the corrosion and corrosion-friction properties of the plasma cladding wear-resistant layer are analyzed. The results indicate that under pure immersion corrosion, the plasma gradient cladding wear-resisting layer has better corrosion resistance compared with that of single cladding specimen. No obvious corrosion traces occur on the corrosion surface. Under corrosion-friction conditions, the variety law of friction coefficient can be divided into four stages: rapid decline zone, slight increase zone, fluctuation zone and steady zone. The fluctuation ranges of friction coefficient and wear loss greatly reduce compared with those of dry friction. Furthermore, the wear scar has no obvious corrosion traces. The wear mechanism of the substrate is corrosion wear, adhesive wear, abrasive wear and fatigue wear, while the plasma cladding gradient wear-resistant layer is given priority to with adhesive wear and abrasive wear.

  1. Statistical Optimization of Reactive Plasma Cladding to Synthesize a WC-Reinforced Fe-Based Alloy Coating

    Science.gov (United States)

    Wang, Miqi; Zhou, Zehua; Wu, Lintao; Ding, Ying; Xu, Feilong; Wang, Zehua

    2018-02-01

    A new compound Fe-W-C powder for reactive plasma cladding was fabricated by precursor carbonization process using sucrose as a precursor. The application of quadratic general rotary unitized design was highlighted to develop a mathematical model to predict and accomplish the desired surface hardness of plasma-cladded coating. The microstructure and microhardness of the coating with optimal parameters were also investigated. According to the developed empirical model, the optimal process parameters were determined as follows: 1.4 for C/W atomic ratio, 20 wt.% for W content, 130 A for scanning current and 100 mm/min (1.67 mm/s) for scanning rate. The confidence level of the model was 99% according to the results of the F-test and lack-of-fit test. Microstructural study showed that the dendritic structure was comprised of a mechanical mixture of α-Fe and carbides, while the interdendritic structure was a eutectic of α-Fe and carbides in the composite coating with optimal parameters. WC phase generation can be confirmed from the XRD pattern. Due to good preparation parameters, the average microhardness of cladded coating can reach 1120 HV0.1, which was four times the substrate microhardness.

  2. Metallic Amorphous Thin Films and Heterostructures with Tunable Magnetic Properties

    OpenAIRE

    Zamani, Atieh

    2015-01-01

    The primary focus of this thesis is to study the effect of doping on magnetic properties in amorphous Fe100−xZrx alloys. Samples with compositions of x = 7,11.6 and 12 at.% were implanted with different concentrations of H. Moreover, the samples with a composition of x = 7 at.% were also implanted with He, B, C and N. Magnetic measurements were performed, using SQUID magnetometry and MOKE, in order to compare the as-grown and the implanted films. The Curie temperature (Tc) increases and the c...

  3. Quantifying the properties of low-cost powder metallurgy titanium alloys

    International Nuclear Information System (INIS)

    Bolzoni, L.; Ruiz-Navas, E.M.; Gordo, E.

    2017-01-01

    The extensive industrial employment of titanium is hindered by its high production costs where reduction of these costs can be achieved using cheap alloying elements and appropriate alternative processing techniques. In this work the feasibility of the production of low-cost titanium alloys is addressed by adding steel to pure titanium and processing the alloys by powder metallurgy. In particular, a spherical 4140 LCH steel powder commonly used in metal injection moulding is blended with irregular hydride-dehydride Ti. The new low-cost alloys are cold uniaxially pressed and sintered under high vacuum and show comparable properties to other wrought-equivalent and powder metallurgy titanium alloys. Differential thermal analysis and X-ray diffraction analyses confirm that Ti can tolerate the employment of iron as primary alloying element without forming detrimental TiFe-based intermetallic phases. Thus, the newly designed α+β alloys could be used for cheaper non-critical components.

  4. Fabrication of a solenoid-type inductor with Fe-based soft magnetic core

    International Nuclear Information System (INIS)

    Lei Chong; Zhou Yong; Gao Xiaoyu; Ding Wen; Cao Ying; Choi, Hyung; Won, Jonghwa

    2007-01-01

    A solenoid-type inductor was fabricated by MEMS (Microelectromechanical systems) technique. The fabrication process uses UV-LIGA, dry etching, fine polishing, and electroplating technique to achieve high performance of the solenoid-type inductor. Fe-based soft magnetic thin film was sputtered as the magnetic core, and polyimide was used as the insulation materials. The inductor was in size of 4x4 mm with coil width of 20 μm and space of 35 μm. The inductance is 1.61 μH at a frequency of 5 MHz with the maximum quality factor of 1.42

  5. Structure, magnetic order and excitations in the 245 family of Fe-based superconductors

    Science.gov (United States)

    Bao, Wei

    2015-01-01

    Elastic neutron scattering simultaneously probes both the crystal structure and magnetic order in a material. Inelastic neutron scattering measures phonons and magnetic excitations. Here, we review the average composition, crystal structure and magnetic order in the 245 family of Fe-based superconductors and in related insulating compounds from neutron diffraction works. A three-dimensional phase-diagram summarizes various structural, magnetic and electronic properties as a function of the sample composition. A high pressure phase diagram for the superconductor is also provided. Magnetic excitations and the theoretic Heisenberg Hamiltonian are provided for the superconductor. Issues for future works are discussed.

  6. Structure, magnetic order and excitations in the 245 family of Fe-based superconductors.

    Science.gov (United States)

    Bao, Wei

    2015-01-21

    Elastic neutron scattering simultaneously probes both the crystal structure and magnetic order in a material. Inelastic neutron scattering measures phonons and magnetic excitations. Here, we review the average composition, crystal structure and magnetic order in the 245 family of Fe-based superconductors and in related insulating compounds from neutron diffraction works. A three-dimensional phase-diagram summarizes various structural, magnetic and electronic properties as a function of the sample composition. A high pressure phase diagram for the superconductor is also provided. Magnetic excitations and the theoretic Heisenberg Hamiltonian are provided for the superconductor. Issues for future works are discussed.

  7. Continuous amorphization of Cu-Zr studied by positron lifetime and two-dimensional Doppler broadening measurements

    International Nuclear Information System (INIS)

    Puff, W.; Rabitsch, H.; Wuerschum, R.; Wilde, G.

    2007-01-01

    Positron lifetime and 2-dimensional Doppler broadening measurements were used to study the amorphization of Cu 60 Zr 40 induced by consecutive folding and rolling. In an intermediate state of folding and rolling cycles a complex microstructure evolves with structural free volumes exhibiting a local environment with enhanced Zr content. In the fully amorphous state after 80 cycles, free volumes of the size of a few missing atoms occur which is contrast to amorphous alloys prepared by melt-spinning. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Effect of γ-(Fe,Ni) crystal-size stabilization in Fe-Ni-B amorphous ribbon

    Science.gov (United States)

    Gorshenkov, M. V.; Glezer, A. M.; Korchuganova, O. A.; Aleev, A. A.; Shurygina, N. A.

    2017-02-01

    The effect of stabilizing crystal size in a melt-quenched amorphous Fe50Ni33B17 ribbon is described upon crystallization in a temperature range of 360-400°C. The shape, size, volume fraction, and volume density have been investigated by transmission electron microscopy and X-ray diffraction methods. The formation of an amorphous layer of the Fe50Ni29B21 compound was found by means of atomic-probe tomography at the boundary of the crystallite-amorphous phase. The stabilization of crystal sizes during annealing is due to the formation of a barrier amorphous layer that has a crystallization temperature that exceeds the crystallization temperature of the matrix amorphous alloy.

  9. Application of mechanical alloying to synthesis of intermetallic phases based alloys

    International Nuclear Information System (INIS)

    Dymek, S.

    2001-01-01

    Mechanical alloying is the process of synthesis of powder materials during milling in high energetic mills, usually ball mills. The central event in mechanical alloying is the ball-powder-ball collision. Powder particles are trapped between the colliding balls during milling and undergo deformation and/or fracture. Fractured parts are cold welded. The continued fracture and cold welding results in a uniform size and chemical composition of powder particles. The main applications of mechanical alloying are: processing of ODS alloys, syntheses of intermetallic phases, synthesis of nonequilibrium structures (amorphous alloys, extended solid solutions, nanocrystalline, quasi crystals) and magnetic materials. The present paper deals with application of mechanical alloying to synthesis Ni A l base intermetallic phases as well as phases from the Nb-Al binary system. The alloy were processed from elemental powders. The course of milling was monitored by scanning electron microscopy and X-ray diffraction. After milling, the collected powders were sieved by 45 μm grid and hot pressed (Nb alloys and NiAl) or hot extruded (NiAl). The resulting material was fully dense and exhibited fine grain (< 1 μm) and uniform distribution of oxide dispersoid. The consolidated material was compression and creep tested. The mechanical properties of mechanically alloys were superior to properties of their cast counterparts both in the room and elevated temperatures. Higher strength of mechanically alloyed materials results from their fine grains and from the presence of dispersoid. At elevated temperatures, the Nb-Al alloys have higher compression strength than NiAl-based alloys processed at the same conditions. The minimum creep rates of mechanically alloyed Nb alloys are an order of magnitude lower than analogously processed NiAl-base alloys. (author)

  10. New Cu-Free Ti-Based Composites with Residual Amorphous Matrix

    Directory of Open Access Journals (Sweden)

    Mircea Nicoara

    2016-04-01

    Full Text Available Titanium-based bulk metallic glasses (BMGs are considered to have potential for biomedical applications because they combine favorable mechanical properties and good biocompatibility. Copper represents the most common alloying element, which provides high amorphization capacity, but reports emphasizing cytotoxic effects of this element have risen concerns about possible effects on human health. A new copper-free alloy with atomic composition Ti42Zr10Pd14Ag26Sn8, in which Cu is completely replaced by Ag, was formulated based on Morinaga’s d-electron alloy design theory. Following this theory, the actual amount of alloying elements, which defines the values of covalent bond strength Bo and d-orbital energy Md, situates the newly designed alloy inside the BMG domain. By mean of centrifugal casting, cylindrical rods with diameters between 2 and 5 mm were fabricated from this new alloy. Differential scanning calorimetry (DSC and X-rays diffraction (XRD, as well as microstructural analyses using optical and scanning electron microscopy (OM/SEM revealed an interesting structure characterized by liquid phase-separated formation of crystalline Ag, as well as metastable intermetallic phases embedded in residual amorphous phases.

  11. Impact of potassium promoter on Cu–Fe based mixed alcohols synthesis catalyst

    International Nuclear Information System (INIS)

    Ding, Mingyue; Tu, Junling; Qiu, Minghuang; Wang, Tiejun; Ma, Longlong; Li, Yuping

    2015-01-01

    Highlights: • Adding K facilitated the immigration of bulky iron species to surface layers. • Adding potassium strengthened the interaction of Fe–K on the surface layers. • Increasing K content facilitated the formation of C 2 + OH. • A maximum in catalytic activity is obtained at 0.5 wt.% of potassium loading. - Abstract: Impacts of K promoter on microstructures of a precipitated Cu–Fe based catalyst were studied by N 2 -physisorption (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and hydrogen temperature-programmed desorption/reduction (H 2 -TPD/TPR). Mixed alcohols synthesis (MAS) was carried out in a fixed-bed reactor. The results indicated that incorporation of K in the Cu–Fe based catalyst decreased the surface area of the particles, whereas promoted the immigration of bulky iron species to surface layers and strengthened the interaction of surface Fe–Cu. The increase of K concentration weakened the H 2 chemisorption and restrained the reduction of both the Cu and Fe species. The catalytic activity and mixed alcohols selectivity increased accompanied with a gradually increasing K concentration, and reached the highest values as the amount of K increased to 0.5 wt.%. Subsequently, the MAS activity and selectivity C 2 + OH presented a decreasing trend. In addition, the increase of K concentration facilitated the formation of heavy hydrocarbons

  12. Micromirror with large-tilting angle using Fe-based metallic glass.

    Science.gov (United States)

    Lee, Jae-Wung; Lin, Yu-Ching; Kaushik, Neelam; Sharma, Parmanand; Makino, Akihiro; Inoue, Akihisa; Esashi, Masayoshi; Gessner, Thomas

    2011-09-01

    For enhancing the micromirror properties like tilting angle and stability during actuation, Fe-based metallic glass (MG) was applied for torsion bar material. A micromirror with mirror-plate diameter of 900 μm and torsion bar dimensions length 250 μm, width 30 μm and thickness 2.5 μm was chosen for the tilting angle tests, which were performed by permanent magnets and electromagnet setup. An extremely large tilting angle of over -270° was obtained from an activation test by permanent magnet that has approximately 0.2 T of magnetic strength. A large mechanical tilting angle of over -70° was obtained by applying approximately 1.1 mT to the mirror when 93 mAwas applied to solenoid setup. The large-tilting angle of the micromirror is due to the torsion bar, which was fabricated with Fe-based MG thin film that has large elastic strain limit, fracture toughness, and excellent magnetic property.

  13. 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 50 Ni 30 P 13 C 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 50 Ni 30 P 13 C 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.

  14. Design and performance of a pulse transformer based on Fe-based nanocrystalline core.

    Science.gov (United States)

    Yi, Liu; Xibo, Feng; Lin, Fuchang

    2011-08-01

    A dry-type pulse transformer based on Fe-based nanocrystalline core with a load of 0.88 nF, output voltage of more than 65 kV, and winding ratio of 46 is designed and constructed. The dynamic characteristics of Fe-based nanocrystalline core under the impulse with the pulse width of several microseconds were studied. The pulse width and incremental flux density have an important effect on the pulse permeability, so the pulse permeability is measured under a certain pulse width and incremental flux density. The minimal volume of the toroidal pulse transformer core is determined by the coupling coefficient, the capacitors of the resonant charging circuit, incremental flux density, and pulse permeability. The factors of the charging time, ratio, and energy transmission efficiency in the resonant charging circuit based on magnetic core-type pulse transformer are analyzed. Experimental results of the pulse transformer are in good agreement with the theoretical calculation. When the primary capacitor is 3.17 μF and charge voltage is 1.8 kV, a voltage across the secondary capacitor of 0.88 nF with peak value of 68.5 kV, rise time (10%-90%) of 1.80 μs is obtained.

  15. 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.

  16. Microstructure and elevated temperature wear behavior of induction melted Fe-based composite coating

    Science.gov (United States)

    Hu, Ge; Meng, Huimin; Liu, Junyou

    2014-10-01

    Fe-based composite coating prepared onto the component of guide wheel using ultrasonic frequency inductive cladding (UFIC) technique has been investigated in terms of microstructure, phase constitutions, microhardness and elevated temperature wear behavior by scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), Vickers microhardness tester and ball-on-disc wear tester. The results indicated that the primary phase in the coating contained austenite γ-Fe, eutectic γ-Fe/(Cr,Fe)2B, boride (Cr,Fe)2B and precipitation enriched in Mo. The average microhardness of the coating was 760 ± 10 HV0.2, which was three times higher than that of the substrate. With increasing temperature, the friction coefficients of the coating and high-chromium cast iron decreased gradually while the wear rates increased during dry sliding wear condition. The relative wear resistance of the coating was 1.63 times higher than that of the high-chromium cast iron at 500 °C, which was ascribed to the hard borides with high thermal stability uniformly embedded in the coating and the formation of dense transfer layer formed onto the worn surface. The high temperature wear mechanism of the coating was dominated by mild abrasive wear. The study revealed that Fe-based composite coating had excellent high temperature wear resistance under dry sliding wear condition.

  17. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  18. Amorphous substances: contribution of Moessbauer spectrometry. Pt. 6. Studies of amorphous metallic alloys and amorphous semiconductors using Moessbauer spectrometry

    International Nuclear Information System (INIS)

    Le Caer, G.; Dubois, J.M.

    1980-01-01

    The sensitivity of Moessbauer spectrometry to the immediate environment of the nucleus is both an advantage and a disadvantage, because all the hyperfine parameters can be a priori distributed. The information related to these distributions (example local chemical order) depends on the hypotheses necessary for calculating the spectra. These hypotheses do not however seriously affect information on the texture or magnetic structure obtainable from the line intensities. These hypotheses are presented together with their consequences, an illustration being given for the case of the 57 Fe isotope. Some typical applications are then given [fr

  19. Anodic Behavior of SAM2X5 Material Applied as Amorphous Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, P D; Farmer, J C; Day, S D; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys are desirable industrial materials since they are highly resistant to corrosion and possess enhanced hardness for wear resistance. The amorphous materials can be produced from the melt as powder and later spray deposited as coatings on large engineering structures. As a laboratory experiment, SAM2X5 powder was coated on electrochemical specimens of 304SS for testing. Results show that the coated specimens did not perform satisfactorily during the laboratory testing. This is because of partial devitrification during the deposition of the powder on the small specimen substrates.

  20. Dependence of tracer diffusion on atomic size in amorphous Ni-Zr

    International Nuclear Information System (INIS)

    Hahn, H.; Averback, R.S.

    1988-01-01

    Tracer diffusion coefficients for several impurities and Ni self-atoms were measured in amorphous (a-) Ni/sub 50/Zr/sub 50/ at 573 K using secondary-ion-mass spectroscopy, Rutherford backscattering, and radioactive tracer methods. The results showed that atomic mobility in the a-Ni-Zr alloy depends strongly on atomic size, decreasing rapidly with increasing atomic radius. This diffusion behavior is similar to that in α-Zr and α-Ti and is suggestive of an interstitial-like mechanism of diffusion. The consequences of these results for solid-state amorphization transformations are discussed