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Sample records for bulk metallic glasses

  1. Toughness of Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Shantanu V. Madge

    2015-07-01

    Full Text Available Bulk metallic glasses (BMGs have desirable properties like high strength and low modulus, but their toughness can show much variation, depending on the kind of test as well as alloy chemistry. This article reviews the type of toughness tests commonly performed and the factors influencing the data obtained. It appears that even the less-tough metallic glasses are tougher than oxide glasses. The current theories describing the links between toughness and material parameters, including elastic constants and alloy chemistry (ordering in the glass, are discussed. Based on the current literature, a few important issues for further work are identified.

  2. Modeling of Microimprinting of Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    Ming CHENG; John A. Wert

    2006-01-01

    A finite element analysis (FEA) model has been developed to analyze microimprinting of bulk metallic glasses (BMG) near the glass transition temperature (Tg). The results reveal an approximately universal imprinting response for BMG, independent of surface feature length scale. The scale-independent nature of BMG imprinting derives from the flow characteristics of BMG in the temperature range above Tg. It also shows that the lubrication condition has a mild influence on BMG imprinting in the temperature range above Tg.

  3. Forming of bulk metallic glass microcomponents

    DEFF Research Database (Denmark)

    Wert, John A.; Thomsen, Christian; Jensen, Rune Debel

    2009-01-01

    The present article considers forward extrusion, closed-die forging and backward extrusion processes for fabrication of individual microcomponents from two bulk metallic glass (BMG) compositions: Mg60Cu30Y10 and Zr44Cu40Ag8Al8. Two types of tooling were used in the present work: relatively massive...

  4. Binary Cu-Zr Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    TANG Mei-Bo; ZHAO De-Qian; PAN Ming-Xiang; WANG Wei-Hua

    2004-01-01

    @@ We report that bulk metallic glasses (BMGs) can be produced up to 2 mm by a copper mould casting in Cux Zr1-x binary alloy with a wide glass forming composition range (45 < x < 60 at.%). We find that the formation mechanism for the binary Cu-Zr binary BMG-forming alloy is obviously different from that of the intensively studied multicomponent BMGs. Our results demonstrate that the criteria for the multicomponent alloys with composition near deep eutectic and strong liquid behaviour are no longer the major concern for designing BMGs.

  5. Fabrication of Porous Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    Keqiang QIU; Yinglei REN

    2005-01-01

    An open-cell porous bulk metallic glass (BMG)with a diameter of at least 6 mm was fabricated by using an U-turn quartz tube and infiltration casting aroundsoluble NaCl placeholders. The pore formation and glassy structure were examined by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the pores or cells are connected to each other and the specimenis composed of a mostly glassy phase.This paper provides a suitable method for fabrication of porous BMG and BMG with larger size in diameter.

  6. Stability of bulk metallic glass structure

    Energy Technology Data Exchange (ETDEWEB)

    Jain, H.; Williams, D.B.

    2003-06-18

    The fundamental origins of the stability of the (Pd-Ni){sub 80}P{sub 20} bulk metallic glasses (BMGs), a prototype for a whole class of BMG formers, were explored. While much of the properties of their BMGs have been characterized, their glass-stability have not been explained in terms of the atomic and electronic structure. The local structure around all three constituent atoms was obtained, in a complementary way, using extended X-ray absorption fine structure (EXAFS), to probe the nearest neighbor environment of the metals, and extended energy loss fine structure (EXELFS), to investigate the environment around P. The occupied electronic structure was investigated using X-ray photoelectron spectroscopy (XPS). The (Pd-Ni){sub 80}P{sub 20} BMGs receive their stability from cumulative, and interrelated, effects of both atomic and electronic origin. The stability of the (Pd-Ni){sub 80}P{sub 20} BMGs can be explained in terms of the stability of Pd{sub 60}Ni{sub 20}P{sub 20} and Pd{sub 30}Ni{sub 50}P{sub 20}, glasses at the end of BMG formation. The atomic structure in these alloys is very similar to those of the binary phosphide crystals near x=0 and x=80, which are trigonal prisms of Pd or Ni atoms surrounding P atoms. Such structures are known to exist in dense, randomly-packed systems. The structure of the best glass former in this series, Pd{sub 40}Ni{sub 40}P{sub 20} is further described by a weighted average of those of Pd{sub 30}Ni{sub 50}P{sub 20} and Pd{sub 60}Ni{sub 20}P{sub 20}. Bonding states present only in the ternary alloys were found and point to a further stabilization of the system through a negative heat of mixing between Pd and Ni atoms. The Nagel and Tauc criterion, correlating a decrease in the density of states at the Fermi level with an increase in the glass stability, was consistent with greater stability of the Pd{sub x}Ni{sub (80-x)}P{sub 20} glasses with respect to the binary alloys of P. A valence electron concentration of 1.8 e/a, which

  7. Cavitation instability in bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    Dai L.H.

    2015-01-01

    Full Text Available Recent experiments have shown that fracture surfaces of bulk metallic glasses (BMGs usually exhibit an intriguing nanoscale corrugation like fractographic feature mediated by nanoscale void formation. We attribute the onset of this nanoscale corrugation to TTZs (tension transformation zones mediated cavitation. In our recent study, the spall experiments of Zr-based BMG using a single-stage light gas gun were performed. To uncover the mechanisms of the spallation damage nucleation and evolution, the samples were designed to be subjected to dynamic tensile loadings of identical amplitude but with different durations by making use of the multi-stress pulse and the double-flyer techniques. It is clearly revealed that the macroscopic spall fracture in BMGs originates from the nucleation, growth and coalescence of micro-voids. Then, a microvoid nucleation model of BMGs based on free volume theory is proposed, which indicates that the nucleation of microvoids at the early stage of spallation in BMGs is resulted from diffusion and coalescence of free volume. Furthermore, a theoretical model of void growth in BMGs undergoing remote dynamic hydrostatic tension is developed. The critical condition of cavitation instability is obtained. It is found that dynamic void growth in BMGs can be well controlled by a dimensionless inertial number characterizing the competition between intrinsic and extrinsic time scales. To unveil the atomic-level mechanism of cavitation, a systematic molecular dynamics (MD simulation of spallation behaviour of a binary metallic glass with different impact velocities was performed. It is found that micro-void nucleation is determined TTZs while the growth is controlled by shear transformation zones (STZs at atomic scale.

  8. Bulk metallic glasses: A new class of engineering materials

    Indian Academy of Sciences (India)

    Joysurya Basu; S Ranganathan

    2003-06-01

    Bulk glass-forming alloys have emerged over the past fifteen years with attractive properties and technological promise. A number of alloy systems based on lanthanum, magnesium, zirconium, palladium, iron, cobalt and nickel have been discovered. Glass-forming ability depends on various factors like enthalpy of mixing, atomic size and multicomponent alloying. A number of processes is available to synthesise bulk metallic glasses. The crystallisation behaviour and mechanical properties of these alloys pose interesting scientific questions. Upon crystallisation many of these glasses transform to bulk nanocrystals and nanoquasicrystals. A detailed study of the structure and the crystallisation behaviour of glasses has enabled the elucidation of the possible atomic configuration in liquid alloys. Their crystallisation behaviour can be exploited to synthesise novel nanocomposite microstructures and their mechanical properties can be enhanced. A broad overview of the present status of the science and technology of bulk metallic glasses and their potential technological uses is presented.

  9. Advanced Manufacturing Technologies (AMT): Bulk Metallic Glass Element

    Data.gov (United States)

    National Aeronautics and Space Administration — The first major objective of the ‘Bulk Metallic Glasses (BMGs) for Space Applications’ project is to raise the technology readiness level dry lubricated,...

  10. Thermoplastic Micro-Forming of Bulk Metallic Glasses: A Review

    Science.gov (United States)

    Li, Ning; Chen, Wen; Liu, Lin

    2016-04-01

    Bulk metallic glasses are a fascinating class of metallic alloys with an isotropic amorphous structure that is rapidly quenched from liquid melts. The absence of a crystalline micro-structure endows them with a portfolio of properties such as high strength, high elasticity, and excellent corrosion resistance. Whereas the limited plasticity and hence poor workability at ambient temperature impede the structural application of bulk metallic glasses, the unique superplasticity within the supercooled liquid region opens an alternative window of so-called thermoplastic forming, which allows precise and versatile net-shaping of complex geometries on length scales ranging from nanometers to centimeters that were previously unachievable with conventional crystalline metal processing. Thermoplastic forming not only breaks through the bottleneck of the manufacture of bulk metallic glasses at ambient temperature but also offers an alluring prospect in micro-engineering applications. This paper comprehensively reviews some pivotal aspects of bulk metallic glasses during thermoplastic micro-forming, including an in-depth understanding of the crystallization kinetics of bulk metallic glasses and the thermoplastic processing time window, the thermoplastic forming map that clarifies the relationship between the flow characteristics and the formability, the interfacial friction in micro-forming and novel forming methods to improve the formability, and the potential applications of the hot-embossed micro-patterns/components.

  11. Crystallization Kinetics of Misch Metal Based Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The crystallization kinetics of Mm55Al25Cu10Ni5Co5 bulk metallic glass (BMG) was investigated by means of differential scanning calorimetry (DSC) in the mode of continuous heating or isothermal annealing. It was found that the apparent activation energy Eg, Ex and Ep of the BMG calculated by Kissinger's method were 189.58, 170.68 and 170.41 kJ·mol-1, respectively, which was bigger than those of La55Al25Cu10Ni5Co5 BMG indicating that thermal stability of the former was higher than that of the latter. The local activation energy obtained using Ozawa equation decreased as crystallization proceeded except for the initial stage. The Avrami exponents were calculated to be in the range of 3.26~5.23 for different crystallization stages and isothermal temperatures. This implied that crystallization of Mm55Al25Cu10Ni5Co5 BMG was governed by diffusion-controlled three-dimensional growth with either reduced or increased nucleation rate, depending on isothermal temperature. Inconsistency of thermal stability with glass-forming ability for Mm(La)-Al-Cu-Ni-Co BMGs was discussed.

  12. Structural features of plastic deformation in bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Scudino, S., E-mail: s.scudino@ifw-dresden.de; Shakur Shahabi, H.; Stoica, M.; Kühn, U. [IFW Dresden, Institut für Komplexe Materialien, D-01069 Dresden (Germany); Kaban, I.; Escher, B.; Eckert, J. [IFW Dresden, Institut für Komplexe Materialien, D-01069 Dresden (Germany); TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden (Germany); Vaughan, G. B. M. [European Synchrotron Radiation Facilities ESRF, BP220, 38043 Grenoble (France)

    2015-01-19

    Spatially resolved strain maps of a plastically deformed bulk metallic glass (BMG) have been created by using high-energy X-ray diffraction. The results reveal that plastic deformation creates a spatially heterogeneous atomic arrangement, consisting of strong compressive and tensile strain fields. In addition, significant shear strain is introduced in the samples. The analysis of the eigenvalues and eigenvectors of the strain tensor indicates that considerable structural anisotropy occurs in both the magnitude and direction of the strain. These features are in contrast to the behavior observed in elastically deformed BMGs and represent a distinctive structural sign of plastic deformation in metallic glasses.

  13. Bulk forming of industrial micro components in conventional metals and bulk metallic glasses

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Paldan, Nikolas Aulin; Eriksen, Rasmus Solmer;

    2007-01-01

    For production of micro components in large numbers, forging is an interesting and challenging process. The conventional metals like silver, steel and aluminum often require multi-step processes, but high productivity and increased strength justify the investment. As an alternative, bulk metallic...... glasses will at elevated temperatures behave like a highly viscous liquid, which can easily form even complicated geometries in 1 step. The strengths and limitations of forming the 2 materials are analyzed for a micro 3D component in a silver alloy and an Mg-Cu-Y BMG. ©2007 American Institute of Physics...

  14. High-rate squeezing process of bulk metallic glasses

    Science.gov (United States)

    Fan, Jitang

    2017-03-01

    High-rate squeezing process of bulk metallic glasses from a cylinder into an intact sheet achieved by impact loading is investigated. Such a large deformation is caused by plastic flow, accompanied with geometrical confinement, shear banding/slipping, thermo softening, melting and joining. Temperature rise during the high-rate squeezing process makes a main effect. The inherent mechanisms are illustrated. Like high-pressure torsion (HPT), equal channel angular pressing (ECAP) and surface mechanical attrition treatments (SMAT) for refining grain of metals, High-Rate Squeezing (HRS), as a multiple-functions technique, not only creates a new road of processing metallic glasses and other metallic alloys for developing advanced materials, but also directs a novel technology of processing, grain refining, coating, welding and so on for treating materials.

  15. Fabrication of bulk metallic glasses by centrifugal casting method

    OpenAIRE

    R. Nowosielski; R. Babilas

    2007-01-01

    Purpose: The aim of the present work is characterization of the centrifugal casting method, apparatus andproduced amorphous materials, which are also known as bulk metallic glassesDesign/methodology/approach: The studied centrifugal casting system consists of two main parts: castingapparatus and injection system of molten alloy. The described centrifugal casting method was presented bypreparing a casting apparatus “CentriCast – 5”. The apparatus includes a cylindrical copper mold, which isrot...

  16. Introduction to bulk metallic glass composite and its recent applications

    OpenAIRE

    2011-01-01

    Bulk metallic glass (BMG) materials are hot topics in recent years, not to mention BMG matrix composites, which further improve the magnetic and mechanical properties of BMG materials. BMG and BMG matrix materials are fast developing and promising materials in modern industry due to their extraordinary properties such as high strength, low density, excellent resistibility to high temperature and corrosion. In this paper, I reviewed processing and application of several recently developed BMG ...

  17. Design of Cu8Zr5-based bulk metallic glasses

    DEFF Research Database (Denmark)

    Yang, L.; Xia, J.H.; Wang, Q.;

    2006-01-01

    Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. This strategy was verified in the Cu-Zr binary syste.......382)(100-x)Nb-x, where x=1.5 and 2.5 at. %, and (Cu0.618Zr0.382)(98)Sn-2. The present results may open a route to prepare amorphous alloys with improved glass forming ability....

  18. Glass Formation Ability and Kinetics of the Gd55Al20Ni25 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    JO Chol-Lyong; XIA Lei; DING Ding; DONG Yuan-Da

    2006-01-01

    @@ We report a new bulk glass-forming alloy Gd55Al20Ni25. The bulk sample of the alloy is prepared in the shape of rods in diameter 2mm by suction casting. The rod exhibits typical amorphous characteristics in the xray diffraction pattern, paramagnetic property at 300K, distinct glass transition and multi-step crystallization behaviour in differential scanning calorimetry traces. The glass formation ability of the alloy is investigated by using the reduced glass transition temperature Tγg and the parameter γ. Kinetics of glass transition and primary crystallization is also studied. The fragility parameter m obtained from the Vogel-Fulcher-Tammann dependence of glass transition temperature Tg on ln φ (φ is the heating rate) classifies the bulk metallic glasses into the intermediate category according to Angells classification.

  19. Ductilizing Bulk Metallic Glass Composite by Tailoring Stacking Fault Energy

    Science.gov (United States)

    Wu, Y.; Zhou, D. Q.; Song, W. L.; Wang, H.; Zhang, Z. Y.; Ma, D.; Wang, X. L.; Lu, Z. P.

    2012-12-01

    Martensitic transformation was successfully introduced to bulk metallic glasses as the reinforcement micromechanism. In this Letter, it was found that the twinning property of the reinforcing crystals can be dramatically improved by reducing the stacking fault energy through microalloying, which effectively alters the electron charge density redistribution on the slipping plane. The enhanced twinning propensity promotes the martensitic transformation of the reinforcing austenite and, consequently, improves plastic stability and the macroscopic tensile ductility. In addition, a general rule to identify effective microalloying elements based on their electronegativity and atomic size was proposed.

  20. Elastic Moduli Inheritance and Weakest Link in Bulk Metallic Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, Alexandru Dan [ORNL; Wang, Xun-Li [ORNL; Lu, Z.P. [University of Science and Technology, Beijing; Clausen, Bjorn [Los Alamos National Laboratory (LANL); Brown, Donald [Los Alamos National Laboratory (LANL)

    2012-01-01

    We show that a variety of bulk metallic glasses (BMGs) inherit their Young s modulus and shear modulus from the solvent components. This is attributed to preferential straining of locally solvent-rich configurations among tightly bonded atomic clusters, which constitute the weakest link in an amorphous structure. This aspect of inhomogeneous deformation, also revealed by our in-situ neutron diffraction studies of an elastically deformed BMG, suggests a scenario of rubber-like viscoelasticity owing to a hierarchy of atomic bonds in BMGs.

  1. Preparation of Cu-based Bulk Metallic Glass Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    Yufeng SUN; Yuren WANG; Bingchen WEI; Weihuo LI

    2006-01-01

    Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) matrix composites containing in situ formed TiC particles and δ-TiCu dendrite phase were developed by copper mold cast. The thermal stability and microstructure of the composites are investigated. Room temperature compression tests reveal that the composite samples exhibit higher fracture strength and distinct plastic strain of 0.2%~0.5%, comparing with that of the corresponding Cu47Ti34Zr11 Ni8 monolithic BMG.

  2. 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.

  3. Formation of ternary Mg–Cu–Dy bulk metallic glasses

    Indian Academy of Sciences (India)

    X F Wu; Y Kang; F F Wu; K Q Qiu; L K Meng

    2011-12-01

    The glass-forming ability (GFA) of ternary Mg–Cu–Dy alloys was systematically investigated by using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) techniques. The results showed that a series of ternary Mg–Cu–Dy bulk metallic glasses (BGMs) with a diameter of 4–8 mm were successfully fabricated in the system with conventional Cu-mold casting method. Mg55Cu32Dy13, Mg60Cu27Dy13, Mg65Cu25Dy10 and Mg70Cu17Dy13 BMGs exhibit a clear glass transition, a broad supercooled liquid region and different crystallization and melting behaviours. They have supercooled liquid region ($\\Delta T_{x}$) from 41 K to 65 K, reduced glass transition temperature ($T_{rg}$) from 0.5363 to 0.5974 and parameter from 0.4038 to 0.4136. The shows a relatively good agreement with the GFA of the BGMs. On the other hand, a high fracture compressive strength of 624 MPa was obtained for Mg60Cu27Dy13 BMG.

  4. A Process for Making Bulk Heavy Metal Fluoride Glasses.

    Science.gov (United States)

    This invention relates to the preparation of glasses, and, in particular, relates to the preparation of heavy metal fluoride glasses with...reproducible high optical qualities. Considerable effort has been expended to develop heavy metal fluoride glasses ( HMFG ) as a viable family of infrared

  5. Stability of Bulk Metallic Glass Structure. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Jain, H.; Williams, D. B.

    2003-06-01

    The fundamental origins of the stability of the (Pd-Ni){sub 80}P{sub 20} bulk metallic glasses (BMGs), a prototype for a whole class of BMG formers, were explored. While much of the properties of their BMGs have been characterized, their glass-stability have not been explained in terms of the atomic and electronic structure. The local structure around all three constituent atoms was obtained, in a complementary way, using extended X-ray absorption fine structure (EXAFS), to probe the nearest neighbor environment of the metals, and extended energy loss fine structure (EXELFS), to investigate the environment around P. The occupied electronic structure was investigated using X-ray photoelectron spectroscopy (XPS). The (Pd-Ni){sub 80}P{sub 20} BMGs receive their stability from cumulative, and interrelated, effects of both atomic and electronic origin. The stability of the (Pd-Ni){sub 80}P{sub 20} BMGs can be explained in terms of the stability of Pd{sub 60}Ni{sub 20}P{sub 20} and Pd{sub 30}Ni{sub 50}P{sub 20}, glasses at the end of BMG formation. The atomic structure in these alloys is very similar to those of the binary phosphide crystals near x=0 and x=80, which are trigonal prisms of Pd or Ni atoms surrounding P atoms. Such structures are known to exist in dense, randomly-packed systems. The structure of the best glass former in this series, Pd{sub 40}Ni{sub 40}P{sub 20} is further described by a weighted average of those of Pd{sub 30}Ni{sub 50}P{sub 20} and Pd{sub 60}Ni{sub 20}P{sub 20}. Bonding states present only in the ternary alloys were found and point to a further stabilization of the system through a negative heat of mixing between Pd and Ni atoms. The Nagel and Tauc criterion, correlating a decrease in the density of states at the Fermi level with an increase in the glass stability, was consistent with greater stability of the Pd{sub x}Ni{sub 80-x}P{sub 20} glasses with respect to the binary alloys of P. A valence electron concentration of 1.8 e/a, which

  6. Corrosion behavior of bulk metallic glasses in different aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.

  7. Self-organized Criticality Behavior in Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    Jun-wei QIAO; Zhong WANG

    2016-01-01

    Serrated flows are known as repeated yielding of bulk metallic glasses (BMGs)during plastic deformation under different loading conditions,which are associated with the operation of shear banding.According to the statis-tics of some parameters,the shear avalanches can display a self-organized critical state,suggesting a large ductility of BMGs.The emergence of the self-organized criticality (SOC)behavior in different BMGs is due to the tempera-ture,strain rate,and chemical compositions.The SOC behavior is accompanied with the following phenomena:the interactions occur in the shear bands;the incubation time is longer than the relaxation time;the time interval is lac-king of typical time scale;and the spatial or temporal parameters should display a power-law distribution.

  8. Fracture characteristics of bulk metallic glass under high speed impact

    Institute of Scientific and Technical Information of China (English)

    Sun Bao-Ru; Zhan Zai-Ji; Liang Bo; Zhang Rui-Jun; Wang Wen-Kui

    2012-01-01

    High speed impact experiments of rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass(BMG)were performed using a two-stage light gas gun.Under spherical shock waves with impact velocities ranging from 0.503 km/s to 4.917 km/s,obvious traces of laminated spallation at the back(free)surface and melting(liquid droplets)at the impact point were observed.The angles about 0°,17°,36°,and 90° to the shocking direction were shown in the internal samples because of the interaction between the compressive shock waves and the rarefaction waves.The compressive normal stress was found to induce the consequent temperature rise in the core of the shear band.

  9. Three-point bending fracture characteristics of bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper presents the SEM micrographs for the three-point bending fracture surfaces of Zr-based, Ce-based and Mg-based bulk metallic glasses (BMGs), which show the dimple structures in the three kinds of BMGs. The shapes of the giant plastic deformation domain on the fracture surface are similar but the sizes are different. The fracture toughness KC and the dimple structure size of the Zr-based BMG are both the largest, and those of the Mg-based BMG are the smallest. The fracture toughness KC and the dimple structure size of the Ce-based BMG are between those of the Zr-based and the Mg-based BMG. Through analyzing the data of different fracture toughnesses of the BMGs, we find that the plastic zone width follows w = (KC/σY)2/(6π).

  10. Developing and Characterizing Bulk Metallic Glasses for Extreme Applications

    Science.gov (United States)

    Roberts, Scott Nolan

    Metallic glasses have typically been treated as a "one size fits all" type of material. Every alloy is considered to have high strength, high hardness, large elastic limits, corrosion resistance, etc. However, similar to traditional crystalline materials, properties are strongly dependent upon the constituent elements, how it was processed, and the conditions under which it will be used. An important distinction which can be made is between metallic glasses and their composites. Charpy impact toughness measurements are performed to determine the effect processing and microstructure have on bulk metallic glass matrix composites (BMGMCs). Samples are suction cast, machined from commercial plates, and semi-solidly forged (SSF). The SSF specimens have been found to have the highest impact toughness due to the coarsening of the dendrites, which occurs during the semi-solid processing stages. Ductile to brittle transition (DTBT) temperatures are measured for a BMGMC. While at room temperature the BMGMC is highly toughened compared to a fully glassy alloy, it undergoes a DTBT by 250 K. At this point, its impact toughness mirrors that of the constituent glassy matrix. In the following chapter, BMGMCs are shown to have the capability of being capacitively welded to form single, monolithic structures. Shear measurements are performed across welded samples, and, at sufficient weld energies, are found to retain the strength of the parent alloy. Cross-sections are inspected via SEM and no visible crystallization of the matrix occurs. Next, metallic glasses and BMGMCs are formed into sheets and eggbox structures are tested in hypervelocity impacts. Metallic glasses are ideal candidates for protection against micrometeorite orbital debris due to their high hardness and relatively low density. A flat single layer, flat BMG is compared to a BMGMC eggbox and the latter creates a more diffuse projectile cloud after penetration. A three tiered eggbox structure is also tested by firing

  11. Fracture behaviors under pure shear loading in bulk metallic glasses

    Science.gov (United States)

    Chen, Cen; Gao, Meng; Wang, Chao; Wang, Wei-Hua; Wang, Tzu-Chiang

    2016-12-01

    Pure shear fracture test, as a special mechanical means, had been carried out extensively to obtain the critical information for traditional metallic crystalline materials and rocks, such as the intrinsic deformation behavior and fracture mechanism. However, for bulk metallic glasses (BMGs), the pure shear fracture behaviors have not been investigated systematically due to the lack of a suitable test method. Here, we specially introduce a unique antisymmetrical four-point bend shear test method to realize a uniform pure shear stress field and study the pure shear fracture behaviors of two kinds of BMGs, Zr-based and La-based BMGs. All kinds of fracture behaviors, the pure shear fracture strength, fracture angle and fracture surface morphology, are systematically analyzed and compared with those of the conventional compressive and tensile fracture. Our results indicate that both the Zr-based and La-based BMGs follow the same fracture mechanism under pure shear loading, which is significantly different from the situation of some previous research results. Our results might offer new enlightenment on the intrinsic deformation and fracture mechanism of BMGs and other amorphous materials.

  12. Computational studies of the glass-forming ability of model bulk metallic glasses.

    Science.gov (United States)

    Zhang, Kai; Wang, Minglei; Papanikolaou, Stefanos; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

    2013-09-28

    Bulk metallic glasses (BMGs) are produced by rapidly thermally quenching supercooled liquid metal alloys below the glass transition temperature at rates much faster than the critical cooling rate R(c) below which crystallization occurs. The glass-forming ability of BMGs increases with decreasing R(c), and thus good glass-formers possess small values of R(c). We perform molecular dynamics simulations of binary Lennard-Jones (LJ) mixtures to quantify how key parameters, such as the stoichiometry, particle size difference, attraction strength, and heat of mixing, influence the glass-formability of model BMGs. For binary LJ mixtures, we find that the best glass-forming mixtures possess atomic size ratios (small to large) less than 0.92 and stoichiometries near 50:50 by number. In addition, weaker attractive interactions between the smaller atoms facilitate glass formation, whereas negative heats of mixing (in the experimentally relevant regime) do not change R(c) significantly. These results are tempered by the fact that the slowest cooling rates achieved in our simulations correspond to ~10(11) K/s, which is several orders of magnitude higher than R(c) for typical BMGs. Despite this, our studies represent a first step in the development of computational methods for quantitatively predicting glass-formability.

  13. Computational studies of the glass-forming ability of model bulk metallic glasses

    Science.gov (United States)

    Zhang, Kai; Wang, Minglei; Papanikolaou, Stefanos; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

    2013-09-01

    Bulk metallic glasses (BMGs) are produced by rapidly thermally quenching supercooled liquid metal alloys below the glass transition temperature at rates much faster than the critical cooling rate Rc below which crystallization occurs. The glass-forming ability of BMGs increases with decreasing Rc, and thus good glass-formers possess small values of Rc. We perform molecular dynamics simulations of binary Lennard-Jones (LJ) mixtures to quantify how key parameters, such as the stoichiometry, particle size difference, attraction strength, and heat of mixing, influence the glass-formability of model BMGs. For binary LJ mixtures, we find that the best glass-forming mixtures possess atomic size ratios (small to large) less than 0.92 and stoichiometries near 50:50 by number. In addition, weaker attractive interactions between the smaller atoms facilitate glass formation, whereas negative heats of mixing (in the experimentally relevant regime) do not change Rc significantly. These results are tempered by the fact that the slowest cooling rates achieved in our simulations correspond to ˜1011 K/s, which is several orders of magnitude higher than Rc for typical BMGs. Despite this, our studies represent a first step in the development of computational methods for quantitatively predicting glass-formability.

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

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2011-04-01

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

  15. Minor alloying behavior in bulk metallic glasses and high-entropy alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of minor alloying on several bulk metallic glasses and high-entropy al-loys was studied. It was found that minor Nb addition can optimize the interface structure between the W fiber and the Zr-based bulk metallic glass in the compos-ites,and improve the mechanical properties. Minor Y addition can destabilize the crystalline phases by inducing lattice distortion as a result to improve the glass-forming ability,and the lattice distortion energy is closely related to the effi-ciency of space filling of the competing crystalline phases. A long-period ordered structure can precipitate in the Mg-based bulk metallic glass by yttrium alloying. For the high-entropy alloys,solid solution can be formed by alloying,and its me-chanical properties can be comparable to most of the bulk metallic glasses.

  16. Structural behavior of Pd40Cu30Ni10P20 bulk metallic glass below and above the glass transition

    DEFF Research Database (Denmark)

    Mattern, N.; Hermann, H.; Roth, S.;

    2003-01-01

    The thermal behavior of the structure of Pd40Cu30Ni10P20 bulk metallic glass has been investigated in situ through the glass transition by means of high-temperature x-ray synchrotron diffraction. The dependence of the x-ray structure factor S(q) of the Pd40Cu30Ni10P20 glass on temperature follows...

  17. Characteristics of Johari-Goldstein relaxations in bulk metallic glasses

    Science.gov (United States)

    Qiao, Jichao; Casalini, Riccardo; Pelletier, Jean-Marc; Kato, Hidemi; Yao, Yao; Yao'S Group Team; Chemistry Division, Naval Research Laboratory Team; Pvmh, Mateis, Insa de Lyon Team; Kato'S Lab Team

    2015-03-01

    The dynamics of Pd-based metallic glasses was studied by mechanical spectroscopy and modulated differential scanning calorimetry. The results show the change in composition has a significant effect on the α relaxation dynamics. All Pd-based metallic glasses have similar fragilities, 59 < m <67, and Kohlrausch stretched exponents, 0.59 <βKWW <0.60. The values of m and βKWW correlate well with the general relation proposed by Böhmer et al. for other glassy materials and the substitution of the Ni with Cu induced a large change in the time constant of the β relaxation, τβ. The activation energy, Uβ, of the β relaxation was generally independent of chemical composition. In all cases, 25 glass formers. From the heat capacity and mechanical loss, the number of dynamically correlated units, Ncwere obtained; significantly larger Nc values for these metallic glasses were observed compared with glassy materials.

  18. Vibrational dynamics of Zr-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    Aditya M.VORA

    2009-01-01

    The vibrational dynamics of some Zr-based bulkmetallic glasses were studied at room temperature in terms of phonon eigen frequencies of longitudinal and transverse modes employing three different approaches proposed by Hubbard-Beeby (HB), Takeno-Goda (TG) and Bhatia-Singh (BS). The well recognized model potential is employed successfully to explain electron-ion interaction in the metallic glass. The present findings of phonon dispersion curve are found to be in fair agreement with available theoretical as well as experimental data. The thermodynamic properties obtained by the HB and TG approaches are found to be much lower than those obtained by the BS approach.

  19. Reentrant spin glass ordering in an Fe-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Qiang; Shen, Jun, E-mail: junshen@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)

    2015-02-07

    We report the results of the complex susceptibility, temperature, and field dependence of DC magnetization and the nonequilibrium dynamics of a bulk metallic glass Fe{sub 40}Co{sub 8}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 2}. Solid indication of the coexistence of reentrant spin glass (SG) and ferromagnetic orderings is determined from both DC magnetization and AC susceptibility under different DC fields. Dynamics scaling of AC susceptibility indicates critical slowing down to a reentrant SG state with a static transition temperature T{sub s} = ∼17.8 K and a dynamic exponent zv = ∼7.3. The SG nature is further corroborated from chaos and memory effects, magnetic hysteresis, and aging behavior. We discuss the results in terms of the competition among random magnetic anisotropy and exchange interactions and compare them with simulation predictions.

  20. Tuning apparent friction coefficient by controlled patterning bulk metallic glasses surfaces

    Science.gov (United States)

    Li, Ning; Xu, Erjiang; Liu, Ze; Wang, Xinyun; Liu, Lin

    2016-12-01

    Micro-honeycomb structures with various pitches between adjacent cells were hot-embossed on Zr35Ti30Cu8.25Be26.75 bulk metallic glass surface. The effect of pitch geometry on the frictional behavior of metallic glass surface was systematically investigated. The results revealed that all textured metallic glass surfaces show a reduction in friction coefficient compared to smooth surface. More intriguingly, the friction coefficient first decreased and then increased gradually with increasing pitches. Such unique behavior can be understood fundamentally from the perspective of competing effects between contact area and local stress level with increasing pitches. This finding not only enhance the in-depth understanding of the mechanism of the significant role of surface topography on the frictional behavior of metallic glass surface, but also opens a new route towards other functional applications for bulk metallic glasses.

  1. Dynamic mechanical behavior of a Zr-based bulk metallic glass during glass transition and crystallization

    Institute of Scientific and Technical Information of China (English)

    CHAO Qi; WANG Qing; DONG Yuanda

    2009-01-01

    The dynamic mechanical behaviors of the Zr41Ti14Cu12.5Ni8Be22.5Fe2 bulk metallic glass (BMG) during continuous heating at a constant rate were investigated. The glass transition and crystallization of the Zr-based BMG were thus characterized by the measurements of storage modulus E and internal friction Q-1. It was found that the variations of these dynamic mechanical quantifies with temperature were interre-lated and were well in agreement with the DSC trace obtained at the same heating rate. The origin of the first peak in the internal friction curve was closely related to the dynamic glass transition and subsequent primary crystallization. Moreover, it can be well described by a physical model, which can characterize atomic mobility and mechanical response of disordered condense materials. In comparison with the DSC trace, the relative position of the first internal friction peak of the BMG was found to be dependent on its thermal stability against crys-tallization.

  2. Fe-B-Y-Nb bulk metallic glasses in relation to clusters

    Institute of Scientific and Technical Information of China (English)

    CHENG Xu; WANG Qing; CHEN WeiRong; DONG Chuang

    2008-01-01

    Bulk metallic glass formations in the Fe-B-Y-Nb quaternary alloy system were in-vestigated by using the cluster line rule in combination with the minor alloying principle. The Fe-B-Y ternary system was selected as the basic system and the intersections of cluster lines were taken as the basic ternary compositions. The basic compositions were further alloyed with minor amounts of Nb. After 3-5 at.% Nb was added, the basic composition Fe68.6B25.7Y5.7, which was developed from the most densely packed cluster Fe8B3, formed 3 mm bulk metallic glasses. These quaternary bulk metallic glasses (Fe68.6B25.7Y5.7)100-xNbx (x=3-5at. %) are expressed approximately with a unified simple composition formula: (Fe8B3)1(Y, Nb)1. The (Fe68.6B25.7Y5.7)97Nb3 bulk metallic glass has the largest glass forming ability with the following characteristic parameters Tg=907 K, Tx=1006 K, Tg/T1=0.644, γ= 0.434, and Iongness t=22 mm. The combination of the cluster line rule and the minor-alloying principle is a promising new route towards the quantitative composition design of multi-component metallic glasses.

  3. Fe-B-Y-Nb bulk metallic glasses in relation to clusters

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Bulk metallic glass formations in the Fe-B-Y-Nb quaternary alloy system were in-vestigated by using the cluster line rule in combination with the minor alloying principle. The Fe-B-Y ternary system was selected as the basic system and the intersections of cluster lines were taken as the basic ternary compositions. The basic compositions were further alloyed with minor amounts of Nb. After 3-5 at.% Nb was added,the basic composition Fe68.6B25.7Y5.7,which was developed from the most densely packed cluster Fe8B3,formed 3 mm bulk metallic glasses. These quaternary bulk metallic glasses (Fe68.6B25.7Y5.7)100-xNbx (x=3-5 at.%) are expressed approximately with a unified simple composition formula: (Fe8B3)1(Y,Nb)1. The (Fe68.6B25.7Y5.7)97Nb3 bulk metallic glass has the largest glass forming ability with the following characteristic parameters Tg=907 K,Tx=1006 K,Tg/Tl=0.644,γ=0.434,and longness t=22 mm. The combination of the cluster line rule and the minor-alloying principle is a promising new route towards the quantitative composition design of multi-component metallic glasses.

  4. Kinetics of Glass Transition and Crystallization in Carbon Nanotube Reinforced Mg-Cu-Gd Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mg65Cu25Gd10 bulk metallic glass and its carbon nanotube reinforced composite were prepared. Differential scanning calorimeter (DSC) was used to investigate the kinetics of glass transition and crystallization processes. The influence of CNTs addition to the glass matrix on the glass transition and crystallization kinetics was studied. It is shown that the kinetic effect on glass transition and crystallization are preserved for both the monothetic glass and its glass composite.Adding CNTs in to the glass matrix reduces the influence of the heating rate on the crystallization process. In addition, the CNTs increase the energetic barrier for the glass transition. This results in the decrease of GFA. The mechanism of the GFA decrease was also discussed.

  5. Effects of cooling rates on the mechanical properties of a Ti-based bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Mechanical properties of the glassy specimens fabricated at different cooling rates with a composition of Ti40Zr25Cu12Ni3Be20 were systematically investigated. It was confirmed that faster cooling rates caused not only a larger amount of frozen-in free volume but also a higher glass transition temperature in the bulk glassy alloy. Increase in the free volume was found to favor plastic deformation and then to give rise to larger compressive plasticity, whilst the rise in the glass transition temperature seemed to be closely related to the higher yield strength. Moreover, the increase of yield strength and plasticity induced by fast cooling rates may also be associated with the residual stress generated during the fabrication process. Our results suggest that the deformation behavior of bulk metallic glasses is sensitive to various factors and influences from the other factors should be excluded as far as cooling-rate effects on bulk metallic glasses are considered.

  6. Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases

    CERN Document Server

    Perim, Eric; Liu, Yanhui; Toher, Cormac; Gong, Pan; Li, Yanglin; Simmons, W Neal; Levy, Ohad; Vlassak, Joost J; Schroers, Jan; Curtarolo, Stefano

    2016-01-01

    Metallic glasses have attracted considerable interest in recent years due to their unique combination of superb properties and processability. Predicting bulk metallic glass formers from known parameters remains a challenge and the search for new systems is still performed by trial and error. It has been speculated that some sort of "confusion" during crystallization of the crystalline phases competing with glass formation could play a key role. Here, we propose a heuristic descriptor quantifying confusion and demonstrate its validity by detailed experiments on two well-known glass forming alloy systems. With the insight provided by these results, we develop a robust model for predicting glass formation ability based on the spectral decomposition of geometrical and energetic features of crystalline phases calculated ab-initio in the AFLOW high throughput framework. Our findings indicate that the formation of metallic glass phases could be a much more common phenomenon than currently estimated, with more than ...

  7. Numerical study of pile-up in bulk metallic glass during spherical indentation

    Institute of Scientific and Technical Information of China (English)

    Al Ke; DAI LanHong

    2008-01-01

    Pile-up around indenter is usually observed during instrumented indentation tests on bulk metallic glass. Neglecting the pile-up effect may lead to errors in evaluating hardness, Young's modulus, stress-strain response, etc. Finite element analysis was employed to implement numerical simulation of spherical indentation tests on bulk metallic glass. A new model was proposed to describe the pile-up effect. By using this new model, the contact radius and hardness of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass were obtained under several different indenter loads with pile-up, and the results agree well with the data generated by numerical simulation.

  8. Linking structure to fragility in bulk metallic glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shuai, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Stolpe, Moritz, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de; Gross, Oliver; Gallino, Isabella; Hembree, William; Busch, Ralf [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Evenson, Zach [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln (Germany); Bednarcik, Jozef [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22603 Hamburg (Germany); Kruzic, Jamie J. [Material Science, School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, Oregon 97331 (United States)

    2015-05-04

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near T{sub g}. The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure.

  9. Numerical study of pile-up in bulk metallic glass during spherical indentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Pile-up around indenter is usually observed during instrumented indentation tests on bulk metallic glass. Neglecting the pile-up effect may lead to errors in evaluating hardness,Young’s modulus,stress-strain response,etc. Finite element analysis was employed to implement numerical simulation of spherical indentation tests on bulk metallic glass. A new model was proposed to describe the pile-up effect. By using this new model,the contact radius and hardness of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass were obtained under several different indenter loads with pile-up,and the results agree well with the data generated by numerical simulation.

  10. Size effect on beta relaxation in a La-based bulk metallic glass

    Science.gov (United States)

    Jiang, Wei; Wu, Jili; Zhang, Bo

    2017-03-01

    This work studied the effect of the size of specimens on the β relaxation. Taking La70Ni15Al15 bulk metallic glass as a model material, via dynamic mechanical analysis, we found that the thickness of specimens can affect the intensity of β relaxation. Specifically, increasing the thickness of specimens can enhance intensity of β relaxation. For this enhancement, we proposed that the involvedly total free volume facilitates the β relaxed process. This finding gives a new insight on the structural relaxation of bulk metallic glasses, especially for understanding of origin of β relaxation.

  11. Shear bands in a bulk metallic glass after large plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Qu, D.D.; Wang, Y.B.; Liao, X.Z.; Shen, J. (Harbin); (Sydney)

    2012-10-23

    A transmission electron microscopy investigation is conducted to trace shear bands in a Zr{sub 53}Cu{sub 18.7}Ni{sub 12}Al{sub 16.3} bulk metallic glass after experiencing 4% plastic deformation. Shear band initiation, secondary shear band interactions, mature shear band broadening and the interactions of shear bands with shear-induced nanocrystals are captured. Results suggest that the plasticity of the bulk metallic glass is enhanced by complex shear bands and their interactions which accommodate large plastic strain and prevent catastrophic shear band propagation.

  12. Wear Behavior of Mechanically Alloyed Ti-Based Bulk Metallic Glass Composites Containing Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    2016-11-01

    Full Text Available The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT particles. Changes in glass transition temperature (Tg and crystallization temperature (Tx suggest that deviations in the chemical composition of the amorphous matrix occurred because of a partial dissolution of the CNT species into the amorphous phase. Although the hardness of CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composites is increased with the addition of CNT particles, the wear resistance of such composites is not directly proportional to their hardness, and does not follow the standard wear law. A worn surface under a high applied load shows that the 12 vol. % CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composite suffers severe wear compared with monolithic Ti50Cu28Ni15Sn7 bulk metallic glass.

  13. In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

    Science.gov (United States)

    Lan, Si; Wei, Xiaoya; Zhou, Jie; Lu, Zhaoping; Wu, Xuelian; Feygenson, Mikhail; Neuefeind, Jörg; Wang, Xun-Li

    2014-11-01

    In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr56Cu36Al8, an average glass former, follows continuous nucleation and growth, while that of Zr46Cu46Al8, a better glass former, is characterized by site-saturated nucleation, followed by slow growth. Possible mechanisms for the observed differences and the relationship to the glass forming ability are discussed.

  14. In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Si; Wei, Xiaoya; Wu, Xuelian; Wang, Xun-Li, E-mail: xlwang@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Ave., Kowloon (Hong Kong); Zhou, Jie; Lu, Zhaoping [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing (China); Feygenson, Mikhail; Neuefeind, Jörg [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-11-17

    In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr{sub 56}Cu{sub 36}Al{sub 8}, an average glass former, follows continuous nucleation and growth, while that of Zr{sub 46}Cu{sub 46}Al{sub 8}, a better glass former, is characterized by site-saturated nucleation, followed by slow growth. Possible mechanisms for the observed differences and the relationship to the glass forming ability are discussed.

  15. Glass Formability and Soft Magnetic Properties of Bulk Y-Fe-B-Ti Metals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Ti effects on the glass forming ability and the magnetic properties of Y-Fe-B-Ti bulk metallic glasses have been investigated. Substituting 2 and 4 at% Ti for Fe or B in Y6Fe70B22 alloys decrease the saturation magnetization (σs) and deteriorate the glass forming ability, respectively. However, substitution of 2 at% Ti for Y in Y6Fe72B22 alloy induces larger supercooled region of 72.7℃, which not only makes the bulk glassy rod as large as 3mm in diameter, but also results in the superior soft magnetic properties of σ5=126emu/g,coercivity ( Hc ) = 0.2 Oe and Curie temperature (Tc) = 268℃. Among all Y-Fe-B-Ti bulk amorphous rods, Y4Fe72B22Ti2 displays the best glass forming ability and also the proper soft magnetic properties.

  16. Transitions of amorphous- crystalline-amorphous in bulk metallic glass under HP and HT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In-situ SR-XRD measurements revealed that the crystallization process in Zr41.2Ti13.sCu12.5Ni10Be22.5 bulk metallic glass is significantly different from that in traditional glasses. Subsequent heating at 10 GPa converts the sample from amorphous phase into the metastable fcc phase and then leads to the fcc phase back to the amorphous phase,nomena in the material under high pressure and high temperature.``

  17. Bulk metallic glass for low noise fluxgate Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The team of Prime Photonics, Virginia Tech, and Utron Kinetics propose to demonstrate a method for fabrication of a bulk, amorphous, cobalt-rich material that...

  18. Fe-based bulk metallic glasses with Y addition

    Energy Technology Data Exchange (ETDEWEB)

    Baser, Tanya Aycan [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P.Giuria, 9-10125 Torino (Italy); Baricco, Marcello [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P.Giuria, 9-10125 Torino (Italy)]. E-mail: marcello.baricco@unito.it

    2007-05-31

    This paper aims to study the role of residual vacuum during sample preparation and of quenching rate on glass formation in Fe{sub 50-x}Cr{sub 15}Mo{sub 14}Y {sub x}C{sub 15}B{sub 6} (x = 0, 2) alloys. The equilibrium phase mixture has been clarified for both alloys, combining X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The beneficial effects of minor addition of Y on the glass formation are evidenced. A high residual vacuum during sample preparation promotes glass formation. Glass transition temperature for amorphous sample containing 2 at.% Y is 881 K and the onset crystallization temperature is 904 K. The melting behavior for both as-cast alloys were measured with high temperature differential scanning calorimeter (HTDSC). Melting starts at 1384 K, ends at 1506 and 1470 K as liquidus temperatures for Fe{sub 50}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6} and Fe{sub 48}Cr{sub 15}Mo{sub 14}Y{sub 2}C{sub 15}B{sub 6} alloys, respectively. The addition of Y leads to a melting behavior of as-cast sample close to eutectic, which enhances glass formation.

  19. Compressive Deformation Induced Nanocrystallization of a Supercooled Zr-Based Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-Lin; SHAN De-Bin; MA Ming-Zhen; GUO Bin

    2008-01-01

    The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high ternperatures.

  20. Compressive behavior of bulk metallic glass under different conditions --- Coupled effect of temperature and strain rate

    Science.gov (United States)

    Yin, Weihua

    Metallic glass was first reported in 1960 by rapid quenching of Au-Si alloys. But, due to the size limitation, this material did not attract remarkable interest until the development of bulk metallic glasses (BMGs) with specimen sizes in excess of 1 mm. BMGs are considered to be promising engineering materials because of their ultrahigh strength, high elastic limit and wear resistance. However, they usually suer from a strong tendency for localized plastic deformation with catastrophic failure. Many basic questions, such as the origin of shear softening and the strain rate eect remain unclear. In this thesis, the mechanical behavior of the Zr55Al 10Ni5Cu30 bulk metallic glass and a metallic glass composite is investigated. The stress-strain relationship for Zr55Al10Ni 5Cu30 over a wide range of strain rate (5x10 --5 to 2x103 s--1) was investigated in uniaxial compression loading using both MTS servo-hydraulic system (quasi-static) and compression Kolsky bar system (dynamic). The effect of the strain rate on the fracture stress at room temperature was discussed. Based on the experimental results, the strain rate sensitivity of the bulk metallic glass changes from a positive value to a negative value at high strain rate, which is a consequence of the significant adiabatic temperature rise during the dynamic testing. In order to characterize the temperature eect on the mechanical behavior of the metallic glass, a synchronically assembled heating unit was designed to be attached onto the Kolsky bar system to perform high temperature and high strain rate mechanical testing. A transition from inhomogeneous deformation to homogeneous deformation has been observed during the quasi-static compressive experiments at testing temperatures close to the glass transition temperature. However, no transition has been observed at high strain rates at all the testing temperatures. A free volume based model is applied to analyze the stress-strain behavior of the homogeneous

  1. Serrated plastic flow during nanoindentation of a bulk metallic glass

    NARCIS (Netherlands)

    Golovin, YI; Ivolgin, [No Value; Khonik, VA; Kitagawa, K; Tyurin, AI

    2001-01-01

    The results of nanoindentation tests of bulk glassy Pd40CU30Ni10P20 using a specially designed instrument with high time and spatial resolution are presented. Pronounced serrations of the indenter penetration depth are observed. The parameters of serrated flow (the number of serrations, their amplit

  2. Estimation of Gibbs free energy difference in Pd-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    Cai Anhui; Xiong Xiang; Liu Yong; Tan JingYing; Zhou Yong; An Weike

    2008-01-01

    A new thermodynamic expression for Gibbs free energy difference 4G between the under-cooled Iiquid and the corresponding crystals of bulk metallic glasses was derived.The newly proposed expression always gives results in fairly good agreement with experimental values over entire temperature range between the fusion temperature Tm and the glass transition temperature Tg of Pd40Ni40P20,Pd40Cu30Ni10P20 and Pd43Cu27Ni10P20,which possess different heat capacities.However,the TS and KN expressions cannot always provide results in good agreement with the experimental values.In addition.the deviations between the experimental values and the △G calculated by the proposed expression at Tg are smaller than those given by other expressions for all the bulk metallic glasses studied.

  3. Glass transition and crystallization process of hard magnetic bulk Nd60Al10Fe20Co10 metallic glass

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Glass transition and crystallization process of bulk Nd60Al10Fe20Co10 metallic glass were investigated by means of dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electronic microscopy (SEM). It is shown that the glass transition and onset crystallization temperature determined by DMTA at a heating rate of 0.167 K/s are 480 and 588 K respectively. The crystallization process of the metallic glass is concluded as follows: amorphous α→α′+metastable FeNdAl novel phase →α′+primary δ phase→primary δ phase+eutectic δ phase Nd3Al phase+Nd3Co phase. The appearance of hard magnetism in this alloy is ascribed to the presence of amorphous phase with highly relaxed structure. The hard magnetism disappeared after the eutectic crystallization of amorphous phase.

  4. Glass transition, crystallization kinetics and pressure effect on crystallization of ZrNbCuNiBe bulk metallic glass

    DEFF Research Database (Denmark)

    Xing, P.F.; Zhuang, Yanxin; Wang, W.H.;

    2002-01-01

    The glass transition behavior and crystallization kinetics of Zr48Nb8Cu14Ni12Be18 bulk metallic glass have been investigated by differential scanning calorimetry and x-ray powder diffraction (XRD). The activation energies of both glass transition and crystallization events have been obtained using...... the Kissinger method. Results indicate that this glass crystallizes by a three-stage reaction: (1) phase separation and primary crystallization of glass, (2) formation of intermetallic compounds, and (3) decomposition of intermetallic compounds and crystallization of residual amorphous phase. The pressure...... effect on crystallization is studied by in situ high-pressure and high-temperature XRD using synchrotron radiation. Two crystallization temperatures, observed by in-situ XRD, behave differently with varying pressure. The onset crystallization temperature increases with pressure with a slope of 9.5 K...

  5. Magnetic properties of Fe-Co-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Tiberto, Paola, E-mail: tiberto@inrim.i [INRIM, Electromagnetism Division, Strada delle Cacce 91, I-10135 Torino (Italy); Piccin, Rafael [Universita di Torino, Dipartimento di Chimica IFM and NIS, I-10125 Torino (Italy); Lupu, Nicoleta; Chiriac, Horia [National Institute of Research and Development for Technichal Physics, 700050 Iasi (Romania); Baricco, Marcello [Universita di Torino, Dipartimento di Chimica IFM and NIS, I-10125 Torino (Italy)

    2009-08-26

    Amorphous [(Fe{sub 1-x}Co{sub x}){sub 75}B{sub 20}Si{sub 5}]{sub 93}Nb{sub 4}Y{sub 3}(x=0, 0.2 and 0.4) have been produced by water-cooled Cu-mold injection casting technique in cylindrical shape. Amorphous ribbon having the same composition have been produced by rapid quenching technique. The presence of an amorphous structure have been checked by means of X-ray diffraction measurements and differential scanning calorimetry. Magnetic hysteresis loops have been measured by means of vibrating sample magnetometer at a maximum field of 10 kOe. In addition, to study the frequency dependence of magnetic losses, hysteresis loops have been measured by a digital wattmeter. A critical analysis of the results obtained on both ribbons and bulk cylinder will be presented. The obtained data will be compared with the ones of Fe-based materials conventionally exploited in applications.

  6. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  7. Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Petre Flaviu Gostin

    2015-07-01

    Full Text Available Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic.

  8. Atomic interaction mechanism for designing the interface of W/Zr-based bulk metallic glass composites

    OpenAIRE

    Li, Z K; Fu, H. M.; Sha, P. F.; Zhu, Z. W.; A. M. Wang; Li, H.; Zhang, H. W.; Zhang, H. F.; Hu, Z. Q.

    2015-01-01

    The interaction between active element Zr and W damages the W fibers and the interface and decreases the mechanical properties, especially the tensile strength of the W fibers reinforced Zr-based bulk metallic glass composites (BMGCs). From the viewpoint of atomic interaction, the W-Zr interaction can be restrained by adding minor elements that have stronger interaction with W into the alloy. The calculation about atomic interaction energy indicates that Ta and Nb preferred to segregate on th...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

  10. Mechanical relaxation in a Zr-based bulk metallic glass: Analysis based on physical models

    Science.gov (United States)

    Qiao, J. C.; Pelletier, J. M.

    2012-08-01

    The mechanical relaxation behavior in a Zr55Cu30Ni5Al10 bulk metallic glass is investigated by dynamic mechanical analysis in both temperature and frequency domains. Master curves can be obtained for the storage modulus G' and for the loss modulus G'', confirming the validity of the time-temperature superposition principle. Different models are discussed to describe the main (α) relaxation, e.g., Debye model, Havriliak-Negami (HN) model, Kohlrausch-Williams-Watt (KWW) model, and quasi-point defects (QPDs) model. The main relaxation in bulk metallic glass cannot be described using a single relaxation time. The HN model, the KWW model, and the QPD theory can be used to fit the data of mechanical spectroscopy experiments. However, unlike the HN model and the KWW model, some physical parameters are introduced in QPD model, i.e., atomic mobility and correlation factor, giving, therefore, a new physical approach to understand the mechanical relaxation in bulk metallic glasses.

  11. High thermal stability and sluggish crystallization kinetics of high-entropy bulk metallic glasses

    Science.gov (United States)

    Yang, M.; Liu, X. J.; Ruan, H. H.; Wu, Y.; Wang, H.; Lu, Z. P.

    2016-06-01

    Metallic glasses are metastable and their thermal stability is critical for practical applications, particularly at elevated temperatures. The conventional bulk metallic glasses (BMGs), though exhibiting high glass-forming ability (GFA), crystallize quickly when being heated to a temperature higher than their glass transition temperature. This problem may potentially be alleviated due to the recent developments of high-entropy (or multi-principle-element) bulk metallic glasses (HE-BMGs). In this work, we demonstrate that typical HE-BMGs, i.e., ZrTiHfCuNiBe and ZrTiCuNiBe, have higher kinetic stability, as compared with the benchmark glass Vitreoy1 (Zr41.2Ti13.8Cu12.5Ni10Be22.5) with a similar chemical composition. The measured activation energy for glass transition and crystallization of the HE-BMGs is nearly twice that of Vitreloy 1. Moreover, the sluggish crystallization region ΔTpl-pf, defined as the temperature span between the last exothermic crystallization peak temperature Tpl and the first crystallization exothermic peak temperature Tpf, of all the HE-BMGs is much wider than that of Vitreloy 1. In addition, high-resolution transmission electron microscopy characterization of the crystallized products at different temperatures and the continuous heating transformation diagram which is proposed to estimate the lifetime at any temperature below the melting point further confirm high thermal stability of the HE-BMGs. Surprisingly, all the HE-BMGs show a small fragility value, which contradicts with their low GFA, suggesting that the underlying diffusion mechanism in the liquid and the solid of HE-BMGs is different.

  12. Wetting of bulk metallic glass forming liquids on metals and ceramics

    Science.gov (United States)

    Ding, Shiyan; Kong, Jian; Schroers, Jan

    2011-08-01

    Contact wetting angle of Pd43Ni10Cu27P20, Pt57.5Cu14.7Ni5.3P22.5, Au49Ag5.5Pd2.3Cu26.9Si16.3, and Zr57Nb5Cu15.4Ni12.6Al10 bulk metallic glass forming alloys have been determined on materials that are used in micro and nano fabrication. Employing the sessile drop technique at a temperature above the corresponding melting temperatures, three kinds of wetting behaviors are observed, spanning from θ ≈ 140°, over neutral wetting, θ ≈ 80°, to almost complete wetting, θ < 5°. The origin for complete wetting is the formation of an interface phase promoting wetting. Estimations of the contact wetting angles are presented for temperatures in the supercooled liquid region where micro and nano fabrication is typically carried out. Consequences of the observed wetting behaviors for nanoforming are discussed.

  13. Formation and mechanical properties of bulk Cu-Ti-Zr-Ni metallic glasses with high glass forming ability

    Institute of Scientific and Technical Information of China (English)

    YANG Ying-jun; KANG Fu-wei; XING Da-wei; SUN Jian-fei; SHEN Qing-ke; SHEN Jun

    2007-01-01

    Bulk amorphous Cu52.5Ti30Zr11.5Ni6 and Cu53.1Ti31.4Zr9.5Ni6 alloys with a high glass forming ability can be quenched into single amorphous rods with a diameter of 5 mm, and exhibit a high fracture strength of 2 212 MPa and 2 184 MPa under compressive condition, respectively. The stress-strain curves show nearly 2% elastic strain limit, yet display no appreciable macroscopic plastic deformation prior to the catastrophic fracture due to highly localized shear bands. The present work shows clearly evidence of molten droplets besides well-developed vein patterns typical of bulk metallic glasses on the fracture surface, suggesting that localized melting induced by adiabatic heating may occur during the final failure event.

  14. Atomistic modelling and prediction of glass forming ability in bulk metallic glasses

    Science.gov (United States)

    Sedighi, Sina

    Atomistic modeling (via molecular dynamics with EAM interaction potentials) was conducted for the detailed investigation of kinetics, thermodynamics, structure, and bonding in Ni-Al and Cu-Zr metallic glasses. This work correlates GFA with the nature of atomic-level bonding and vibrational properties, with results potentially extensible to the Transition Metal -- Transition Metal and Transition Metal -- Metalloid alloy classes in general. As a first step in the development of a liquid-only GFA tuning approach, an automated tool has also been created for the broad compositional sampling of liquid and glassy phase properties in multicomponent (binary, ternary, quaternary) alloy systems. Its application to the Cu-Zr alloy system shows promising results, including the successful identification of the two highest GFA compositions, Cu50Zr50 and Cu64Zr 36. Combined, the findings of this work highlight the critical importance of incorporating more complex alloy-specific information regarding the nature of bonding and ordering at the atomic level into such an approach.

  15. Elastic properties of superconducting bulk metallic glasses; Elastische Eigenschaften von supraleitenden massiven metallischen Glaesern

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Marius

    2015-07-01

    Within the framework of this thesis the elastic properties of a superconducting bulk metallic glass between 10 mK and 300 K were first investigated. In order to measure the entire temperature range, in particular the low temperature part, new experimental techniques were developed. Using an inductive readout scheme for a double paddle oscillator it was possible to determine the internal friction and the relative change of sound velocity of bulk metallic glasses with high precision. This allowed for a detailed comparison of the data with different models. The analysis focuses on the low temperature regime where the properties of glassy materials are governed by atomic tunneling systems as described by the tunneling model. The influence of conduction electrons in the normal conducting state and quasiparticles in the superconducting state of the glass were accounted for in the theoretical description, resulting in a good agreement over a large temperature range between measured data and prediction of the tunneling model. This allowed for a direct determination of the coupling constant between electrons and tunneling systems. In the vicinity of the transition temperature Tc the data can only be described if a modified distribution function of the tunneling parameters is applied.

  16. Nearest-neighbor coordination and chemical ordering in multi-component bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dong [ORNL; Stoica, Alexandru Dan [ORNL; Yang, Ling [ORNL; Wang, Xun-Li [ORNL; Lu, Zhao Ping [ORNL; Neuefeind, Joerg C [ORNL; Kramer, Matthew J [ORNL; Richardson, James W [Argonne National Laboratory (ANL); Proffen, Thomas E [ORNL

    2007-01-01

    We report complimentary use of high energy x-ray and neutron diffraction to probe the local atomic structure in a Zr-based multi-component bulk metallic glass. By analyzing the partial coordination numbers, we demonstrate the presence of multiple types of solute-centered clusters (or the lack of solute-solute bonding) and efficient packing of the amorphous structure at the atomic scale. Our findings provide a basis for understanding how the local structures change during phase transformation and mechanical deformation.

  17. Deformation-induced martensitic transformation in Cu-Zr-Al(Ti) bulk metallic glass composites

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ram Bachchan; Pauly, Simon; Das, Jayanta; Eckert, Juergen [Institut fuer Komplexe Materialien, IFW Dresden (Germany)

    2009-07-01

    Plastic deformation of Cu-Zr-(Al, Ti) bulk metallic glass (BMG) composites induces a martensitic phase transformation from the B2 to the B19* CuZr phase. Addition of Ti to binary Cu-Zr increases the temperature above which the B2 CuZr phase becomes stable. This affects the phase formation upon quenching in Cu-Zr-Ti BMG composites. The deformation-induced martensitic transformation is believed to cause the strong work hardening and to contribute to the large compressive deformability with plastic strains up to 15%.

  18. Crystallization and thermophysical properties of Cu46Zr47Al6Co1 bulk metallic glass

    Directory of Open Access Journals (Sweden)

    Kang Wu

    2013-11-01

    Full Text Available Phase evolution of two-step crystallization and the subsequent B2-phase transformation was presented in Cu46Zr47Al6Co1 bulk metallic glass (BMG during heating process. Thermophysical properties, i.e. the thermal diffusivity and the specific heat capacity, of the BMG in amorphous solid state and supercooled liquid state as well as its crystalline counterparts were measured from room temperature to 1070 K. The thermal conductivity was also calculated through combination of the data of the thermal diffusivity and the specific heat capacity. The possible influence of the crystallization on the thermophysical properties was discussed.

  19. Modeling deformation behavior of Cu-Zr-Al bulk metallic glass matrix composites

    Science.gov (United States)

    Pauly, S.; Liu, G.; Wang, G.; Das, J.; Kim, K. B.; Kühn, U.; Kim, D. H.; Eckert, J.

    2009-09-01

    In the present work we prepared an in situ Cu47.5Zr47.5Al5 bulk metallic glass matrix composite derived from the shape memory alloy CuZr. We use a strength model, which considers percolation and a three-microstructural-element body approach, to understand the effect of the crystalline phase on the yield stress and the fracture strain under compressive loading, respectively. The intrinsic work-hardenability due to the martensitic transformation of the crystalline phase causes significant work hardening also of the composite material.

  20. Fatigue Properties and Morphology of Fatigue Fracture of Bulk Metallic Glass

    Science.gov (United States)

    Zhao, X. Y.; Chen, Z. H.; Wang, H. P.; Zhan, J.

    2016-11-01

    Changes in the amorphous structure and fatigue resistance of Zr57.5Cu27.3Al8.5Ni6.7 bulk metallic glass are studied. A copper-rich phase produced by cyclic stresses is discovered. This phase observed on the fracture surface may hinder crack propagation. The specimens after fatigue failure have a V shape (do not break into two completely) due to the high density of shear bands and multiple branching of the shear bands in the strained region.

  1. Deformation-strengthening during rolling Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Hu, Yuyan

    2007-01-01

    Mechanical strength evolutions during rolling the Cu60Zr20Ti20 bulk metallic glass (BMG) at room temperature (RT) and cryogenic temperature (CT) have been investigated by measuring the microhardness. The hardness slightly increases during the initial rolling stage as a result of the gradually...... enhanced microinhomogeneity of chemical composition, and then dramatically rises owing to phase separation at CT or phase separation plus nanocrystallization at RT. It is revealed that the Cu-rich separated amorphous phases from the matrix possess higher strengths than the original and Cu-poor separated...

  2. Excellent Magnetocaloric Effect in Er6oAl18Co22 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    HUI Xi-Dong; XU Zhi-Yi; WANG En-Rui; CHEN Guo-Liang; LU Zhao-Ping

    2010-01-01

    @@ Excellent magnetocaloric effect with a maximum entropy change and refrigeration capacity of 17.6 J.kg-1.K-1 and 546 J.kg-1,respectively,has been discovered in the Er60Al18 Co22 bulk metallic glass under the fleld of 50 kOe in the temperature range of helium liquefaction.This MCE results from the second-order magnetic transition from the paramagnetic to the ferromagnetic state.Our analysis based on mean-field theory suggests that the excellent MCE is attributed to the strong exchange of magnetic moment in the glassy structure.

  3. Castable Bulk Metallic Glass Strain Wave Gears: Towards Decreasing the Cost of High-Performance Robotics

    Science.gov (United States)

    Hofmann, Douglas C.; Polit-Casillas, Raul; Roberts, Scott N.; Borgonia, John-Paul; Dillon, Robert P.; Hilgemann, Evan; Kolodziejska, Joanna; Montemayor, Lauren; Suh, Jong-Ook; Hoff, Andrew; Carpenter, Kalind; Parness, Aaron; Johnson, William L.; Kennett, Andrew; Wilcox, Brian

    2016-11-01

    The use of bulk metallic glasses (BMGs) as the flexspline in strain wave gears (SWGs), also known as harmonic drives, is presented. SWGs are unique, ultra-precision gearboxes that function through the elastic flexing of a thin-walled cup, called a flexspline. The current research demonstrates that BMGs can be cast at extremely low cost relative to machining and can be implemented into SWGs as an alternative to steel. This approach may significantly reduce the cost of SWGs, enabling lower-cost robotics. The attractive properties of BMGs, such as hardness, elastic limit and yield strength, may also be suitable for extreme environment applications in spacecraft.

  4. Crystallization mechanism of CeAlFeCo bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    王志新; 卢金斌; 席艳君

    2010-01-01

    Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.

  5. Insight on the glass-forming ability of Al–Y–Ni–Ce bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shih-Fan, E-mail: sfchen@ntut.edu.tw [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China); Chen, Chih-Yuan, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Lin, Chia-Hung [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China)

    2015-07-15

    Highlights: • Adding 1 at.% cerium to Al{sub 87}Y{sub 8}Ni{sub 5} alloy causes glass transition. • A large ΔT{sub x} indicates that (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} is possibly a ductile amorphous alloy. • Ce is effective in improving the thermal stability of the Al–Y–Ni amorphous alloy. • The hardness of the crystallized cerium-bearing alloy was as high as 593 Hv. - Abstract: In the present study, the role of Ce in the thermal stability and glass forming ability (GFA) of (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbons produced by a single roller melt-spinning process has been investigated in an attempt to understand the influences of multiple RE elements in an Al–TM–RE (TM: transition metal, RE: rear earth metal) alloy system. Only the (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbon showed a glass transition temperature (T{sub g}) at 483.2 K, and its ΔT{sub x} value was 41.3 K. Crystallization occurred in the temperature range of 500–750 K in three exothermic reaction stages. The peak temperature for these reactions shifted toward higher temperatures at higher heating rates. XRD and SEM analysis of annealed samples revealed that nano-sized Al particles precipitated within the amorphous matrix during the first exothermic reaction. The maximum hardness was obtained for both non-cerium and cerium addition alloys after crystallization in the 550–660 K region due to numerous nano-sized precipitates randomly and homogeneously distributed in the amorphous matrix. Moreover, from observation of the fracture surface, it is found that the fracture mode transforms from ductile to brittle when the sample is annealed at a higher crystallization temperature, at which brittle intermetallic compounds appear.

  6. Development of bulk metallic glasses based on the Dy-Al binary eutectic composition

    Institute of Scientific and Technical Information of China (English)

    LUO Lin; TIAN Rui; XIAO Xueshan

    2008-01-01

    A series of dysprosium-based ternary, quadruple, and quintuple bulk metallic glasses (BMGs) based on Dy-Al binary eutectic compo-sition were obtained with the partial substitution of Co, Gd, and Ni elements, for dysprosium. The results showed that the Dy31Gd25Co20Al24 alloy, which had the best glass forming ability (GFA), could be cast into an amorphous rod with a diameter of 5 mm. The GFA of alloys was evaluated on the basis of the supercooled liquid region width, γ parameter, the formation enthalpy, and the equivalent electronegativity difference of amor-phous alloys. It was found that the eutectic composition was closely correlated with the GFA of the Dy-based BMGs.

  7. Microstructure and mechanical properties of a novel Zr-based bulk metallic glass composite

    Institute of Scientific and Technical Information of China (English)

    SUN Yufeng; WANG Yuren; GUO Jian; WEI Bingchen; LI Weihuo

    2005-01-01

    Zr48.5Cu46.5Al5 bulk metallic glass (BMG) composites with diameters of 3 and 4 mm were prepared through suction casting in an arc melting furnace by modulating the alloy composition around the monothetic BMG composition of the high glass forming ability. Microstructural characterization reveals that the composites contain micron-sized CuZr phase with martensite structure, as well as nano-sized Zr2Cu crystalline particles and Cu10Zr7 plate-like phase embedded in an amorphous matrix. Room temperature compression tests showed that the composites exhibited significant strain hardening and obvious plastic strain of 7.7% for 3 mm and 6.4% for 4 mm diameter samples, respectively.

  8. Surface Crystallization in Mg-Based Bulk Metallic Glass during Copper Mold Casting

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2014-01-01

    Full Text Available The localized crystallization of Mg54Cu28Ag7Y11 bulk metallic glass (BMG in the injection casting process using a copper mold was investigated. It has been found that several crystalline phases were formed close to the as-cast surface but did not exist in the internal part of the BMG plate. It is abnormal that the as-cast surface is partially crystallized with higher cooling rate than that of inside. Overheating of the melt and nucleation induced by the surface of copper mold play key roles in the abnormal crystallization. It is suggested that the function of copper mold to trigger heterogeneous nucleation cannot be totally ignored, although it provides the high cooling rate for the glass formation during casting.

  9. Ni-based Ni-Fe-B-Si-Ta bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The glass-forming ability and properties of Ni-based Ni-Fe-B-Si-Ta bulk metallic glasses are explored in this work. The alloy compositions are determined by using a combination of the cluster line approach, the multi-alloying strategy and the substitutions of similar elements. Bulk metallic glasses with diameters of 3 mm take shape at compositions formulated under the clus- ter-plus-glue-atom model [M9B]B~[(Ni1-xFex)7.71(Si0.66Ta0.34)1.29B]B0.94=(Ni1-xFex)70.5B17.7Si7.8Ta4, x=0.35–0.45, where the bracketed part is the cluster and the unbracketed part is the glue atoms. These alloys exhibit good magnetic properties. The maximum Is is found in the (Ni0.55Fe0.45)70.5B17.7Si7.8Ta4 alloy which reaches 0.51 T, with its Hc as low as 8.5 A/m. Interestingly, these alloys display dual glass transitions at (Ni0.65Fe0.35)70.5B17.7Si7.8Ta4, (Ni0.60Fe0.4)70.5B17.7Si7.8Ta4 and (Ni0.55Fe0.45)70.5B17.7- Si7.8Ta4 as unveiled by Temperature-Modulated Differential Scanning Calorimetry.

  10. Reformation Capability of Short-Range Order and Their Medium-Range Connections Regulates Deformability of Bulk Metallic Glasses

    Science.gov (United States)

    Li, Congling; Wei, Yujie; Shi, Xinghua

    2015-07-01

    Metallic glasses (MGs) typically have high yield strength while low ductility, and the latter is commonly considered as the Achilles’ heel of MGs. Elucidate the mechanism for such low ductility becomes the research focus of this field. With molecular level simulations, we show the degree of short-range order (SRO) of atomic structure for brittle Fe-based glass decreases dramatically during the stretch, while mild change occurs in ductile Zr-based glass. The reformation capability for SRO and their medium-range connections is found to be the primary characteristics to differentiate the deformability between the two metallic glasses. We suspect that, in addition to the strength of networks formed by SRO structure, the reformation capability to reform SRO networks also plays the key role in regulating the ductility in metallic glasses. Our study provides important insights into the understanding about the mechanisms accounting for ductility or brittleness of bulk metallic glasses.

  11. Effect of physical aging on Johari-Goldstein relaxation in La-based bulk metallic glass

    Science.gov (United States)

    Qiao, Jichao; Casalini, Riccardo; Pelletier, Jean-Marc

    2014-09-01

    The influence of physical aging on the β relaxation in La60Ni15Al25 bulk metallic glass has been investigated by mechanical spectroscopy. The amplitude of the β relaxation (ΔG″) decreases while its relaxation time (τβ) increases during aging. We find that, as in organic glasses, the changes of ln (τβ) and ln (ΔGmax ) are linearly correlated with ln (τβ) = b - a ln (G_max^''). This behavior is discussed in term of the asymmetric double-well potential (ADWP) model, with U and Δ the energies characterizing the ADWP. It is suggested that during aging the ratio U/Δ remains approximately constant, with a value close to the coefficient describing the linear correlation between ln (τβ) and ln (G_max^'')(U/Δ ˜ a). Moreover, the evolution versus aging time of ΔGmax can be described by a simple stretched exponential equation giving values of τaging consistent with tan(δ) measurements during aging. The very similar behavior of the β relaxation during aging in metallic glasses and organic material strongly suggests a common nature for this relaxation.

  12. Glass-Forming Ability and Early Crystallization Kinetics of Novel Cu-Zr-Al-Co Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Xiaoliang Han

    2016-09-01

    Full Text Available In recent years, CuZr-based bulk metallic glass (BMG composites ductilized by a shape memory B2 CuZr phase have attracted great attention owing to their outstanding mechanical properties. However, the B2 CuZr phase for most CuZr-based glass-forming compositions is only stable at very high temperatures, leading to the uncontrollable formation of B2 crystals during quenching. In this work, by introducing Co (i.e., 4, 5, and 6 at. % and 10 at. % Al into CuZr-based alloys, the relatively good glass-forming ability (GFA of CuZr-based alloys still can be achieved. Meanwhile, the B2 phase can be successfully stabilized to lower temperatures than the final temperatures of crystallization upon heating CuZr-based BMGs. Unlike previous reported CuZr-based BMGs, the primary crystallization products upon heating are mainly B2 CuZr crystals but not CuZr2 and Cu10Zr7 crystals. Furthermore, the primary precipitates during solidification are still dominated by B2 crystals, whose percolation threshold is detected to lie between 10 ± 2 vol. % and 31 ± 2 vol. %. The crystallization kinetics underlying the precipitation of B2 crystals was also investigated. Our results show that the present glass-forming composites are promising candidates for the fabrication of ductile CuZr-based BMG composites.

  13. Roles of nanoclusters in shear banding and plastic deformation of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Nieh, T G

    2012-07-31

    During the course of this research we published 33 papers in various physics/material journals. We select four representing papers in this report and their results are summarized as follows. I. To study shear banding process, it is pertinent to know the intrinsic shear strain rate within a propagating shear band. To this aim, we used nanoindentation technique to probe the mechanical response of a Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glass in locality and found notable pop-in events associated with shear band emission. Using a free volume model and under the situation when temperature and stress/hardness are fixed result in an equation, which predicts that hardness serration caused by pop-in decreases exponentially with the strain rate. Our data are in good agreement with the prediction. The result also predicts that, when strain rate is higher than a critical strain rate of 1700 s^-1, there will be no hardness serration, thereby no pop-in. In other words, multiple shear bandings will take place and material will flow homogeneously. The critical strain rate of 1700 s^-1 can be treated as the intrinsic strain rate within a shear band. We subsequently carried out a simulation study and showed that, if the imposed strain rate was over , the shear band spacing would become so small that the entire sample would virtually behave like one major shear band. Using the datum strain rate =1700 s^-1 and based on a shear band nucleation model proposed by us, the size of a shear-band nucleus in Au-BMG was estimated to be 3 10^6 atoms, or a sphere of ~30 nm in diameter. II. Inspired by the peculiar result published in a Science article Super Plastic Bulk Metallic Glasses at Room Temperature, we synthesized the Zr-based bulk metallic glass with a composition identical to that in the paper (Zr64.13Cu15.75Ni10.12Al10) and, subsequently, tested in compression at the same slow strain rate (~10^-4 s^-1). We found that the dominant deformation mode is always single shear. The stress

  14. Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses.

    Science.gov (United States)

    Zhang, Kai; Smith, W Wendell; Wang, Minglei; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

    2014-09-01

    We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio α, and number fraction x(S) of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate R(c), below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with α≳0.8 that do not demix, R(c) decreases strongly with Δϕ(J), as R(c)∼exp(-1/Δϕ(J)(2)), where Δϕ(J) is the difference between the average packing fraction of the amorphous packings and random crystal structures at R(c). Systems with α≲0.8 partially demix, which promotes crystallization, but we still find a strong correlation between R(c) and Δϕ(J). We show that known metal-metal BMGs occur in the regions of the α and x(S) parameter space with the lowest values of R(c) for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing α to increase packing efficiency, while maximizing α to prevent demixing.

  15. Microstructure and mechanical properties of Zr-Cu-Al bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Zr49Cu46Al5 and Zr48.5Cu46.5Al5 bulk metallic glasses(BMGs) with diameter of 5 mm were prepared through water-cooled copper mold casting. The phase structures of the two alloys were identified by X-ray diffractometry(XRD). The thermal stability was examined by differential scanning calorimetry(DSC). Zr49Cu46Al5 alloy shows a glass transition temperature, Tg, of about 689 K, an crystallization temperature, Tx, of about 736 K. The Zr48.5Cu46.5Al5 alloy shows no obvious exothermic peak. The microstructure of the as-cast alloys was analyzed by transmission electron microscopy(TEM). The aggregations of CuZr and CuZr2 nanocrystals with grain size of about 20 nm are observed in Zr49Cu46Al5 nanocrystalline composite, while the Zr48.5Cu46.5Al5 alloy containing many CuZr rmartensite plates is crystallized seriously. Mechanical properties of bulk Zr49Cu46Al5 nanocrystalline composite and Zr48.5Cu46.5Al5 alloy measured by compression tests at room temperature show that the work hardening ability of Zr48.5Cu46.5Al5 alloy is larger than that of Zr49Cu46Al5 alloy.

  16. Locating Malleable Bulk Metallic Glasses in Zr-Ti-Cu-Al Alloys with Calorimetric Glass Transition Temperature as an Indicator

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    We defined the plastic deformability under constrained loading conditions as malleability for bulk metallic glass (BMG) materials. Quaternary Zr-Ti-Cu-Al alloys in the Zr-rich composition range are selected to investigate the compositional dependence of malleability assessed by bending testing and glass transition temperature (Tg ). As indicated, increasing the Al or Cu concentration in the alloys leads to the rise of T g . The Zr(61)Ti2Cu(25)Al(12) (ZT1) and Zr(61.6)Ti(4.4)Cu(24)Al(10) (ZT3) alloys exhibit an optimal combination of lower T g and higher glass-forming ability. The malleable BMGs such as ZT1 manifests two characters during deformation, the stable propagation of a single shear band indicated by large shear offsets and easy proliferation of shear bands. With increasing the T g of BMG, the yield strength σy,Young's modulus and shear modulus simultaneously increase as well, while the Poisson s ratio decreases. The σy of ZT1 BMG is about 1680 MPa in compression and 1600 MPa in tension. In tensile loading, no any visible plasticity appears even when the strain rate increases up to the order of magnitude of 10(-1)s(-1). In consistent with the T g , malleability of Zr-Ti-Cu-Al BMGs manifests significant compositional dependence. The malleable BMG is associated with lower Tg , as well as lower shear modulus or higher Poisson s ratio, which can be understood on the basis of the correlation of Tg with shear energy barrier in metallic glass. Thus, the calorimetric Tg can be used as an indicator to screen malleable BMG-forming composition, with advantage of experimental accessibility.

  17. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Science.gov (United States)

    Li, Jiawei; Huo, Juntao; Law, Jiayan; Chang, Chuntao; Du, Juan; Man, Qikui; Wang, Xinmin; Li, Run-Wei

    2014-08-01

    The effects of heavy rare earth (RE) additions on the Curie temperature (TC) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune TC in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔSM) and refrigerant capacity (RC) of the alloys. The observed values of ΔSM and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd5Ge1.9Si2Fe0.1. The tunable TC and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  18. High plastic Zr-Cu-Fe-Al-Nb bulk metallic glasses for biomedical applications

    Science.gov (United States)

    Wang, Shu-shen; Wang, Yun-liang; Wu, Yi-dong; Wang, Tan; Hui, Xi-dong

    2015-06-01

    Four Zr-Cu-Fe-Al-based bulk metallic glasses (BMGs) with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr-Cu-Fe-Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson's ratio and low Young's and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316L steel in phosphate buffer solution (PBS, pH 7.4). The combination of the optimized composition with high deformation ability, low Young's modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.

  19. Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature.

    Science.gov (United States)

    Tan, J; Wang, G; Liu, Z Y; Bednarčík, J; Gao, Y L; Zhai, Q J; Mattern, N; Eckert, J

    2014-01-28

    A model Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) is selected to explore the structural evolution on the atomic scale with decreasing temperature down to cryogenic level using high energy X-ray synchrotron radiation. We discover a close correlation between the atomic structure evolution and the strength of the BMG and find out that the activation energy increment of the concordantly atomic shifting at lower temperature is the main factor influencing the strength. Our results might provide a fundamental understanding of the atomic-scale structure evolution and may bridge the gap between the atomic-scale physics and the macro-scale fracture strength for BMGs.

  20. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    LI Lei; LIU Yuan; ZHANG TaiHua; GU JianSheng; WEI BingChen

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore, it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work, the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow, the typical plastic deformation feature of BMGs, could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition, the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  1. Deformation behavior during nanoindentation in Ce-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingchen; XING Dongmei; ZHANG Taihua; WEI Bingchen; LI Weihuo; WANG Yuren

    2006-01-01

    The deformation behavior and the effect of the loading rate on the plastic deformation in Ce-based bulk metallic glasses (BMGs) were investigated through nanoindentation tests. The results showed that the loading rate dependence of plastic deformation during nanoindentation measurements in the Ce-based BMGs is quite unique in contrast to that of other BMG alloys. The load-displacement (P-h)curves of Ce60Al15Cu10Ni15 BMG exhibit a homogeneous plastic deformation at low loading rates, and a prominent serrated flow at high strain rates, whereas,the P-h curves of Ce65Al10Cu10Ni10Nb5 exhibit homogenous plastic deformation at all studied loading rates. The room temperature creep behavior could clearly be observed in these two alloys. The mechanism of the unique plastic deformation feature in the Ce-based BMGs was studied.

  2. Microstructure of Cu60Zr20Ti20 bulk metallic glass rolled at different strain rates

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The structural evolution of Cu60Zr20Ti20 bulk metallic glass during rolling at different strain rates and cryogenic temperature was investigated by X-ray diffraction (XRD),differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HRTEM). It is revealed that the deformation-induced transformation is strongly dependent on the strain rate. At the lowest experimental strain rate of 1.0×10-4 s-1,no phase transformation occurs until the highest deformation degree reaches 95%. In a strain rate range of 5.0×10-4-5.0×10-2 s-1,phase separation oc-curs in a high deformation degree. As the strain rate reaches 5.0×10-1 s-1,phase separation and nanocrystallization concur. The critical deformation degree for oc-currence of phase transformation decreases with the strain rate increasing.

  3. Deformation and failure of bulk metallic glasses under different initial temperatures

    Directory of Open Access Journals (Sweden)

    Li J.C.

    2015-01-01

    Full Text Available Based on the coupled thermo-mechanical model, a constitutive model for bulk metallic glasses (BMGs, which is generalized to the multi-axial stress state and considers the effects of free volume, heat and hydrostatic stress, has been modified in the present paper. Besides, a failure criterion of critical free volume concentration is introduced based on the coalescence mechanism of free volume. The constitutive model as well as the failure criterion is implemented into the LS-DYNA commercial software by user material subroutine (UMAT. Then FEM simulations for different initial material temperatures are conducted and the evolutions of material parameter as well as corresponding macroscopic mechanical behaviour of material are analyzed. Relative analysis shows that the initial material temperature significantly affects the deformation and failure of material.

  4. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore,it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work,the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow,the typical plastic deformation feature of BMGs,could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition,the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  5. Atomic interaction mechanism for designing the interface of W/Zr-based bulk metallic glass composites

    Science.gov (United States)

    Li, Z. K.; Fu, H. M.; Sha, P. F.; Zhu, Z. W.; Wang, A. M.; Li, H.; Zhang, H. W.; Zhang, H. F.; Hu, Z. Q.

    2015-03-01

    The interaction between active element Zr and W damages the W fibers and the interface and decreases the mechanical properties, especially the tensile strength of the W fibers reinforced Zr-based bulk metallic glass composites (BMGCs). From the viewpoint of atomic interaction, the W-Zr interaction can be restrained by adding minor elements that have stronger interaction with W into the alloy. The calculation about atomic interaction energy indicates that Ta and Nb preferred to segregate on the W substrate surface. Sessile drop experiment proves the prediction and corresponding in-situ coating appears at the interface. Besides, the atomic interaction mechanism was proven to be effective in many other systems by the sessile drop technique. Considering the interfacial morphology, Nb was added into the alloy to fabricate W/Zr-based BMGCs. As expected, the Nb addition effectively suppressed the W-Zr reaction and damage to W fibers. Both the compressive and tensile properties are improved obviously.

  6. Crystallization of a Ti-based Bulk Metallic Glass Induced by Electropulsing Treatment

    Institute of Scientific and Technical Information of China (English)

    Yong-jiang HUANG; Xiang CHENG; Hong-bo FAN; Shi-song GUAN; Zhi-liang NING; Jian-fei SUN

    2016-01-01

    The effect of electropulsing treatment (EPT)on the microstructure of a Ti-based bulk metallic glass (BMG)has been studied.The maximum current density applied during EPT can exert a crucial role on tuning the microstructure of the BMG.When the maximum current density is no more than 2 720 A/mm2 ,the samples retains amorphous nature,whereas,beyond that,crystalline phases precipitate from the glassy matrix.During EPT,the maximum temperature within the samples EPTed at the maximum current densities larger than 2 720 A/mm2 is higher than the crystallization temperature of the BMG,leading to the crystallization event.

  7. The effect of high energy concentration source irradiation on structure and properties of Fe-based bulk metallic glass

    Science.gov (United States)

    Pilarczyk, Wirginia

    2016-06-01

    Metallic glasses exhibit metastable structure and maintain this relatively stable amorphous state within certain temperature range. High intensity laser beam was used for the surface irradiation of Fe-Co-B-Si-Nb bulk metallic glasses. The variable parameter was laser beam pulse energy. For the analysis of structure and properties of bulk metallic glasses and their surface after laser remelting the X-ray analysis, microscopic observation and test of mechanical properties were carried out. Examination of the nanostructure of amorphous materials obtained by high pressure copper mold casting method and the irradiated with the use of TITAN 80-300 HRTEM was carried out. Nanohardness and reduced Young's modulus of particular amorphous and amorphous-crystalline material zone of the laser beam were examined with the use of Hysitron TI950 Triboindenter nanoindenter and with the use of Berkovich's indenter. The XRD and microscopic analysis showed that the test material is amorphous in its structure before irradiation. Microstructure observation with electron transmission microscopy gave information about alloy crystallization in the irradiated process. Identification of given crystal phases allows to determine the kind of crystal phases created in the first place and also further changes of phase composition of alloy. The main value of the nanohardness of the surface prepared by laser beam has the order of magnitude similar to bulk metallic glasses formed by casting process irrespective of the laser beam energy used. Research results analysis showed that the area between parent material and fusion zone is characterized by extraordinarily interesting structure which is and will be the subject of further analysis in the scope of bulk metallic glasses amorphous structure and high energy concentration source. The main goal of this work is the results' presentation of structure and chosen properties of the selected bulk metallic glasses after casting process and after irradiation

  8. Mechanical Properties, Damage and Fracture Mechanisms of Bulk Metallic Glass Materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses (BMGs) and their composites. The shear fracture angles of these BMG materials often display obvious differences under compression and tension,and follow either the Mohr-Coulomb criterion or the unified tensile fracture criterion. The compressive plasticity of the composites is always higher than the tensile plasticity, leading to a significant inconsistency. The enhanced plasticity of BMG composites containing ductile dendrites compared to monolithic glasses strongly depends on the details of the microstructure of the composites. A deformation and damage mechanism of pseudo-plasticity, related to local cracking, is proposed to explain the inconsistency of plastic deformation under tension and compression. Besides, significant melting on the shear fracture surfaces was observed. It is suggested that melting is a common phenomenon in these materials with high strength and high elastic energy, as it is typical for BMGs and their composites failing under shear fracture. The melting mechanism can be explained by a combined effect of a significant temperature rise in the shear bands and the instantaneous release of the large amount of elastic energy stored in the material.

  9. Enhancement of glass-forming ability of Fe-based bulk metallic glasses with high saturation magnetic flux density

    Directory of Open Access Journals (Sweden)

    Mingxiao Zhang

    2012-06-01

    Full Text Available The effects of substituting Fe with Ni on thermal properties, glass-forming ability (GFA and magnetic properties of Fe76-xNixMo3.5P10C4B4Si2.5 (x = 0−30 at.% alloys were investigated in detail. The breadth of the supercooled liquid region was found to gradually increase from 42 to 55 K with increasing Ni content to 30 at.%. When x = 5 at.%, the alloy composition approached a eutectic point, resulting in an increase in GFA. As a result, FeNiMoPCBSi bulk metallic glasses with critical diameters up to 5.5 mm were successfully synthesized by copper mold casting. These glassy alloys exhibit a high saturation magnetic flux density of 0.75−1.21 T and excellent soft magnetic properties, i.e., low coercive force of 1.1−2.0 A/m, and high effective permeability of 14400−19700 at 1 kHz under a field of 1 A/m. The reasons for the high stability of the supercooled liquid, and the high GFA as well as excellent soft magnetic properties are discussed in this article.

  10. In vitro and in vivo studies on biodegradable CaMgZnSrYb high-entropy bulk metallic glass.

    Science.gov (United States)

    Li, H F; Xie, X H; Zhao, K; Wang, Y B; Zheng, Y F; Wang, W H; Qin, L

    2013-11-01

    In order to enhance the corrosion resistance of the Ca65Mg15Zn20 bulk metallic glass, which has too fast a degradation rate for biomedical applications, we fabricated the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass because of the unique properties of high-entropy alloys. Our results showed that the mechanical properties and corrosion behavior were enhanced. The in vitro tests showed that the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass could stimulate the proliferation and differentiation of cultured osteoblasts. The in vivo animal tests showed that the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass did not show any obvious degradation after 4 weeks of implantation, and they can promote osteogenesis and new bone formation after 2 weeks of implantation. The improved mechanical properties and corrosion behavior can be attributed to the different chemical composition as well as the formation of a unique high-entropy atomic structure with a maximum degree of disorder.

  11. Mechanically driven phase separation and corresponding microhardness change in Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.;

    2005-01-01

    Rolling deformation of bulk Cu60Zr20Ti20 metallic glass has been performed at cryogenic temperature. The specimens exhibit excellent ductility, and are rolled up to 97% reduction in thickness without fracture. Crystallization is suppressed during the deformation, however, phase separation is obse...

  12. Effect of rolling deformation on the microstructure of bulk Cu60Zr20Ti20 metallic glass and its crystallization

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.;

    2006-01-01

    Bulk Cu60Zr20Ti20 metallic glass has been rolled at room temperature (RT) and cryogenic temperature (CIF) up to 97% in thickness reduction, and the dependences of microstructure on the strain and temperature have been investigated. It is revealed that as the deformation proceeds below a critical...

  13. Bulk metallic glass formation in the Pd-Ni-P and Pd-Cu-P alloy systems

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, R.B.; He, Y. [Los Alamos National Lab., NM (United States). Center for Materials Science

    1996-12-11

    Bulk metallic glasses were prepared in the Pd-Ni-P and Pd-Cu-P systems using a fluxing technique. The formation of bulk amorphous Pd-Cu-P alloys was reported here for the first time. For both alloy systems, bulk glass formation requires maintaining the phosphorus content near 20 at.%. In the Pd-Ni-P system, 10-mm diameter amorphous Pd{sub x}Ni{sub 80{minus}x}P{sub 20} rods can be formed for 25 {le} x {le} 60. In the Pd-Cu-P system, 7-mm diameter amorphous Pd{sub x}Cu{sub 80{minus}x}P{sub 20} rods can be produced for 40 {le} x {le} 60. From all the ternary alloys studied, Pd{sub 40}Ni{sub 40}P{sub 20} has the highest glass formability, and 25-mm diameter amorphous cylinders, 50 mm in length, can be easily fabricated. The glass stability of the Pd-Ni-P system is wider than that of the Pd-Cu-P system. For most bulk Pd-Ni-P glasses, {Delta}T > 90 K. The {Delta}T values of bulk amorphous Pd-Cu-P alloys are considerably smaller, ranging from 27 to 73 K. The elastic constants of bulk amorphous Pd-Ni-P and Pd-Cu-P alloys were determined using a resonant ultrasound spectroscopy technique. The Pd-Ni-P glasses are slightly stiffer than the Pd-Cu-P glasses. Within each alloy system, the Young`s modulus and the bulk modulus show little change with alloy composition. Of all the bulk glass forming systems so far investigated, the ternary Pd-Ni-P system has the best glass formability. This alloy was one of the first bulk glasses discovered, yet it still remains the best in terms of glass formability. Upon replacing part of Ni by Cu, the critical cooling rates are expected to be further reduced.

  14. The Evolution of Microstructures and the Properties of Bulk Metallic Glass with Consubstantial Composition Laser Welding

    Directory of Open Access Journals (Sweden)

    Pingjun Tao

    2016-09-01

    Full Text Available A Zr55Cu30Ni5Al10 plate-like bulk metallic glass (BMG was prepared using copper mold suction casting. Additionally, alloy powders with the same nominal composition were synthesized. The alloy powders were welded or melted to the cleaned surface of the BMG with a laser beam acceleration voltage of 60 kV, a beam current range from 60 to 100 mA, a welding speed of 60 mm/s, as well as an impulse width of 3.0 ms. The effect of consubstantial composition welding on the microstructures and properties was investigated. The molten and subsequently solidified metallic mixtures remain an amorphous structure, but the enthalpy of the welded or melted position varies due to the combination of the micro-structural relaxation and nano-crystals precipitated during the energy inputs. The surface layers of the BMG can be significantly intensified after welding processes; however, the heat-affected zones (HAZs exhibit a slight degradation in mechanical properties with respect to the BMG matrix. This study has important reference value for specialists working on the promotion of applications of BMGs.

  15. Crystallization behavior of Fe- and Co-based bulk metallic glasses and their glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Louzguine-Luzgin, D.V., E-mail: dml@wpi-aimr.tohoku.ac.jp [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Bazlov, A.I. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation); Ketov, S.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [International Institute of Green Materials, Josai International University, Togane 283-8555 (Japan); School of Materials Science and Engineering, Tianjin University, 300072 (China); Department of Physics, King Abdulaziz University, Jeddah 22254 (Saudi Arabia)

    2015-07-15

    In the present work we study and compare the crystallization behavior of Fe- and Co-based good bulk glass formers with an exceptionally high glass-forming ability leading to the critical thickness of cast samples reaching 1 cm. For Fe-based alloys we also investigate the effect of opposite C/B content ratio on the glass-forming ability and the crystallization behavior. The structure and phase composition of the glassy samples were examined by conventional X-ray diffractometry and transmission electron microscopy while thermal stability and phase transformations were studied by differential scanning calorimetry. The reasons for high glass-forming ability are discussed. The glass-forming ability of the studied alloys depends on both factors: the type of crystallization reaction and characteristic temperatures. - Highlights: • Crystallization of Fe-based and Co-based bulk glass-forming alloys. • The reasons for enhanced glass-forming ability of these alloys are discussed. • Low growth rate of χ-Fe{sub 36}Cr{sub 12}Mo{sub 10} phase. • Reduced liquidus temperature of Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 6}B{sub 15}RE{sub 2} alloys.

  16. A Series of Zr-Based Bulk Metallic Glasses with Room Temperature Plasticity

    Directory of Open Access Journals (Sweden)

    Anhui Cai

    2016-05-01

    Full Text Available A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature Tg decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index β for the studied Zr-based BMGs. The plastic strain εp is in the region of 0.2%–19.1% for these Zr-based BMGs. Both yield strength σy and fracture strength σf are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose εp is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.

  17. Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Dianyu Wu

    2015-11-01

    Full Text Available The microstructures and mechanical properties of (Cu0.5Zr0.5100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. % bulk metallic glass (BMG composites were studied. CuZr martensitic crystals together with minor B2 CuZr and amorphous phases dominate the microstructures of the as-quenched samples with low Zn additions (x = 0, 1.5, and 2.5 at. %, while B2 CuZr and amorphous phases being accompanied with minor martensitic crystals form at a higher Zn content (x = 4.5, 7, 10, and 14 at. %. The fabricated Cu-Zr-Zn BMG composites exhibit macroscopically appreciable compressive plastic strain and obvious work-hardening due to the formation of multiple shear bands and the deformation-induced martensitic transformation (MT within B2 crystals. The present BMG composites could be a good candidate as high-performance structural materials.

  18. Simulation study of mechanical properties of bulk metallic glass systems: martensitic inclusions and twinned precipitates

    Science.gov (United States)

    Zaheri, A.; Abdeljawad, F.; Haataja, M.

    2014-12-01

    Monolithic bulk metallic glasses (BMGs) exhibit a unique combination of mechanical properties, such as high strength and large elasticity limits, but the lack of ductility is considered the main Achilles' heel of BMG systems. To increase the competitiveness of BMGs vis-à-vis conventional structural materials, the problem of catastrophic failure via intense plastic strain localization (‘shear banding’) has to be addressed. Recent experimental observations suggest that the addition of structural heterogeneities, in the form of crystalline particles, to BMG systems hinders the catastrophic propagation of shear bands and leads to enhanced ductility. These structural heterogeneities can be introduced by either forming BMG composites, where second-phase crystalline particles accommodate applied loads via martensitic transformation mechanisms, or developing glassy alloys that precipitate crystalline particles under deformation, a process by which further deformation can be sustained by twinning mechanisms in the crystalline phase. In this work, we present a non-linear continuum model capable of capturing the structural heterogeneity in the glassy phase and accounting for intrinsic work hardening via martensitic transformations in second-phase reinforcements in BMG composites and deformation twinning in precipitated crystalline particles. Simulation results reveal that in addition to intrinsic work hardening in the crystalline phase, particle size greatly affects the overall mechanical behavior of these BMG systems. The precipitation of crystalline particles in monolithic BMGs yields two-phase microstructures that promote more homogeneous deformation, delay the propagation of incipient shear bands, and ultimately result in improved ductility characteristics.

  19. Structural and mechanical modifications induced on Zr-based bulk metallic glass by laser shock peening

    Science.gov (United States)

    Zhu, Yunhu; Fu, Jie; Zheng, Chao; Ji, Zhong

    2016-12-01

    In this study, surface modification of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk metallic glass (BMG) has been studied in an effort to improve the mechanical properties by laser shock peening (LSP) treatment. The phase structure, mechanical properties, and microstructural evolution of the as-cast and LSP treated specimens were systematically investigated. It was found that the vit1 BMG still consisted of fully amorphous structure after LSP treatment. Measurements of the heat relaxation indicate that a large amount of free volume is introduced into vit1 BMG during LSP process. LSP treatment causes a decrease of hardness attributable to generation of free volume. The plastic deformation ability of vit1 BMG was investigated under three-point bending conditions. The results demonstrate that the plastic strain of LSP treated specimen is 1.83 times as large as that of the as-cast specimen. The effect of LSP technology on the hardness and plastic deformation ability of vit1 BMG is discussed on the basis of free volume theory. The high dense shear bands on the side surface, the increase of striations and critical shear displacement on the tensile fracture region, and more uniform dimples structure on the compressive fracture region also demonstrate that the plasticity of vit1 BMG can be enhanced by LSP.

  20. AC Calorimetry and Thermophysical Properties of Bulk Glass-Forming Metallic Liquids

    Science.gov (United States)

    Johnson, William L.

    2000-01-01

    Thermo-physical properties of two bulk metallic glass forming alloys, Ti34Zr11Cu47Ni8 (VIT 101) and Zr57Nb5Ni12.6Al10CU15.4 (VIT 106), were investigated in the stable and undercooled melt. Our investigation focused on measurements of the specific heat in the stable and undercooled liquid using the method of AC modulation calorimetry. The VIT 106 exhibited a maximum undercooling of 140 K in free radiative cooling. Specific heat measurements could be performed in stable melt down to an undercooling of 80 K. Analysis of the specific heat data indicate an anomaly near the equilibrium liquidus temperature. This anomaly is also observed in y the temperature dependencies of the external relaxation time, the specific volume, and the surface tension; it is tentatively attributed to a phase separation in the liquid state. The VIT 101 specimen exhibited a small undercooling of about 50 K. Specific heat measurements were performed in the stable and undercooled melt. These various results will be combined with ground based work such as the measurement of T-T-T curves in the electrostatic levitator and low temperature viscosity and specific heat measurements for modeling the nucleation kinetics of these alloys.

  1. Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

    Science.gov (United States)

    Wright, Wendelin J.; Liu, Yun; Gu, Xiaojun; Van Ness, Katherine D.; Robare, Steven L.; Liu, Xin; Antonaglia, James; LeBlanc, Michael; Uhl, Jonathan T.; Hufnagel, Todd C.; Dahmen, Karin A.

    2016-02-01

    Two distinct types of slip events occur during serrated plastic flow of bulk metallic glasses. These events are distinguished not only by their size but also by distinct stress drop rate profiles. Small stress drop serrations have fluctuating stress drop rates (with maximum stress drop rates ranging from 0.3-1 GPa/s), indicating progressive or intermittent propagation of a shear band. The large stress drop serrations are characterized by sharply peaked stress drop rate profiles (with maximum stress drop rates of 1-100 GPa/s). The propagation of a large slip is preceded by a slowly rising stress drop rate that is presumably due to the percolation of slipping weak spots prior to the initiation of shear over the entire shear plane. The onset of the rapid shear event is accompanied by a burst of acoustic emission. These large slips correspond to simultaneous shear with uniform sliding as confirmed by direct high-speed imaging and image correlation. Both small and large slip events occur throughout plastic deformation. The significant differences between these two types require that they be carefully distinguished in both modeling and experimental efforts.

  2. Serrated flow behaviors of a Zr-based bulk metallic glass by nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, L.; Jiao, Z. M.; Ma, S. G.; Wang, Z. H., E-mail: qiaojunwei@gmail.com, E-mail: wangzhihua@tyut.edu.cn [Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Qiao, J. W., E-mail: qiaojunwei@gmail.com, E-mail: wangzhihua@tyut.edu.cn [Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2014-02-28

    Instrumented nanoindentation tests were used to investigate the mechanical properties of Zr{sub 52.5}Cu{sub 17.9}Ni{sub 14.6}Al{sub 10}Ti{sub 5} bulk metallic glass. The corresponding loading strain rates were ranged from 0.002 s{sup −1}, 0.02 s{sup −1} to 0.2 s{sup −1}. Plastic flow of this material exhibited remarkable serrations at low strain rates and increasingly became weakening until disappearance with increasing indentation strain rate, implying strong rate sensitivity. A significant pile-up around the indents was observed through atomic force microscopy, which suggested a highly localized plastic deformation. Mechanism governing the deformation was tentatively discussed in terms of the increasing process of free volume with a negligible temperature rise under low strain rate, which well explained the declining trend of elastic modulus and hardness with an increase of indentation depth.

  3. Wear behaviour of Zr-based in situ bulk metallic glass matrix composites

    Indian Academy of Sciences (India)

    X F WU; G A ZHANG; F F WU

    2016-06-01

    Zr-based bulk metallic glass (BMG) and its in situ BMG matrix composites with diameter of 3 mm were fabricated by conventional Cu-mould casting method and the dry sliding wear behaviour of the BMG and composites was investigated. Compared to the pure BMG, the composites exhibited a markedly improved wear resistance from 10 to 48% due to the existence of various volume fractions of the ductile $\\beta$-Zr dendritic phase embedded in the glassy matrix. The composites showed lower friction coefficient and wear rate than the pure BMG. Meanwhile, the surface wearing of the composite with a proper amount of $\\beta$-Zr dendrites was less severe compared to that of the pure BMG. The worn surface of the composite was covered with mild grooves and some fine wear debris, which exhibited the characteristic of a mild abrasive wear. The improvement of the wear resistance of the composite with the proper amount of $\\beta$-Zr crystalline phase is attributed to the fact that the $\\beta$-Zr crystalline phase distributed in the amorphous matrix has some effective load bearing, plastic deformation and work hardening ability to decrease strain accumulation and the release of strain energy in the glassy matrix, restrict the expanding of shear bands and cracks, and occur plastic deformation homogeneously.

  4. Local melting to design strong and plastically deformable bulk metallic glass composites

    Science.gov (United States)

    Qin, Yue-Sheng; Han, Xiao-Liang; Song, Kai-Kai; Tian, Yu-Hao; Peng, Chuan-Xiao; Wang, Li; Sun, Bao-An; Wang, Gang; Kaban, Ivan; Eckert, Jürgen

    2017-02-01

    Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties. Through adjusting local melting process parameters (i.e. input powers, local melting positions, and distances between the electrode and amorphous plate), the size, volume fraction, and distribution of B2 crystals were well tailored and the corresponding formation mechanism was clearly clarified. The resultant BMG composites exhibit large compressive plasticity and high strength together with obvious work-hardening ability. This compelling approach could be of great significance for the steady development of metastable CuZr-based alloys with excellent mechanical properties.

  5. Domain structure of hard magnetic NdAIFeCo bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnetic domain structure of hard magnetic Nd60Al10Fe20Co10 bulk metallic glass (BMG) has been studied by using magnetic force microscopy. In the magnetic force images it is shown that the exchange interaction type mag netic domains with a period of about 360 nm do exist in the BMG, which is believed to be associated with the appearance of hard-magnetic properties in this system. As the scale of the magnetic domain is much larger than the size of the short-range ordered atomic clusters existing in the BMG, it is believed that the large areas of magnetic contrast are actu ally a collection of a group of clusters aligned in parallel by strong exchange coupling interaction. After fully crystalliza tion, the BMG exhibits paramagnetism. No obvious magnetic contrast is observed in the magnetic force images of fully crystallized samples, except for a small quantity of ferro magnetic crystalline phase with low coercivity and an average size of 900 nm.

  6. An interatomic potential for studying CuZr bulk metallic glasses

    DEFF Research Database (Denmark)

    Paduraru, Anca; Kenoufi, Abdel; Bailey, Nicholas;

    2007-01-01

    The mechanical properties of BMGs are remarkably different from the ones of ordinary metallic alloys due to the atomic level disorder in the glassy state. Unlike crystalline materials plastic deformation in metallic glasses cannot be caused by lattice defects but takes place through atomic...

  7. A Kinetic Study of the Non-isothermal Crystallization of a Zr-Based Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    柳林; 吴志方; 陈莉

    2002-01-01

    The kinetics of the non-isothermal crystallization ofZr55 Cu30Al10Ni5 bulk metallic glass was studied by differentialscanning calorimetry in the mode of continuous heating. It is found that both glass transition and crystallizationof the amorphous alloy behave in a marked kinetic nature. The activation energy E and frequency factor c0 forcrystallization were determined by the Kissinger method, which yields E = 230 kJ/mol, and k0 = 4.2 × l0Ca/s.The value of k0 is much smaller than that for conventional amorphous alloys, demonstrating that the atomicmobility in bulk metallic glasses is quite sluggish. The crystallization mechanism in the non-isothermal processwas analysed in terms of the kinetic transformation equation for the solid-state phase transformation. Thisreveals that the crystallization kinetic function f (x) for Zr55 Cu30Al10Ni5 can be described by the Johnson-Mehl-Avrami equation, i.e. f(x) = (1 - x)[- ln(1 - x)](n-1)/n, with n = 1.75. This indicates that the non-isothermalcrystallization of Zr55 Cu30Al10Ni5 bulk metallic glass is governed by diffusion-controlled one-dimensional growth.Finally, the different crystallization mechanisms in the isothermal and non-isothermal processes are discussed.

  8. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    Science.gov (United States)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  9. Effects of density difference of constituent elements on glass formation in TiCu-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    Zhongyan Zhang; Zengbao Jiao; Jie Zhou; Yuan Wu; Hui Wang; Xiongjun Liu; Zhaoping Lun

    2013-01-01

    Glass formation is generally favored by a large atomic size mismatch among constituent elements, which usually leads to large density differences among them as well. During melting, elemental segregation occurs due to Stokes’ law and then inevitably affects glass formation. In this paper, such effects on glass-forming ability in a TiCu-based alloy system have been demonstrated. In the bulk glass-forming composition Ti43Cu42Hf14Si1, macroscopic segregation of Si was observed in the as-melted ingots and silicon was completely depleted in the as-cast rods. In another Ti33Cu47Ni8Zr11Si1 alloy, nevertheless, the effects of density differences among the constituent elements were less severe. It was also confirmed that using proper pre-alloys could be an effective way in alleviating the side effects of the elemental segregation.

  10. Joining and Assembly of Bulk Metallic Glass Composites Through Capacitive Discharge

    Science.gov (United States)

    Hofmann, Douglas C.; Roberts, Scott; Kozachkov, Henry; Demetriou, Marios D.; Schramm, Joseph P.; Johnson, William L.

    2012-01-01

    Bulk metallic glasses (BMGs), a class of amorphous metals defined as having a thickness greater than 1 mm, are being broadly investigated by NASA for use in spacecraft hardware. Their unique properties, attained from their non-crystalline structure, motivate several game-changing aerospace applications. BMGs have low melting temperatures so they can be cheaply and repeatedly cast into complex net shapes, such as mirrors or electronic casings. They are extremely strong and wear-resistant, which motivates their use in gears and bearings. Amorphous metal coatings are hard, corrosion-resistant, and have high reflectivity. BMG composites, reinforced with soft second phases, can be fabricated into energy-absorbing cellular panels for orbital debris shielding. One limitation of BMG materials is their inability to be welded, bonded, brazed, or fastened in a convenient method to form larger structures. Cellular structures (which can be classified as trusses, foams, honeycombs, egg boxes, etc.) are useful for many NASA, commercial, and military aerospace applications, including low-density paneling and shields. Although conventional cellular structures exhibit high specific strength, their porous structures make them challenging to fabricate. In particular, metal cellular structures are extremely difficult to fabricate due to their high processing temperatures. Aluminum honeycomb sandwich panels, for example, are used widely as spacecraft shields due to their low density and ease of fabrication, but suffer from low strength. A desirable metal cellular structure is one with high strength, combined with low density and simple fabrication. The thermoplastic joining process described here allows for the fabrication of monolithic BMG truss-like structures that are 90% porous and have no heat-affected zone, weld, bond, or braze. This is accomplished by welding the nodes of stacked BMG composite panels using a localized capacitor discharge, forming a single monolithic structure

  11. High-throughput Exploration of Glass Formation via Laser Deposition and the Study of Heterogeneous Microstructure in a Bulk Metallic Glass Alloy

    Science.gov (United States)

    Tsai, Peter T.

    Bulk metallic glasses are a relatively novel class of engineering alloys characterized by a "disordered" atomic structure devoid of long-range translational symmetry. Compared to crystalline alloys, the confluence of metallic bonding and amorphous structure imbues bulk metallic glasses with a unique set of properties that makes them particularly attractive for a wide variety of structural applications. Such properties include exceptional yield strengths, high elastic resilience, resistance to corrosion, and in particular, the unparalleled ability among metals to be thermoplastically formed across a wide range of length scales when heated above the glass transition temperature. Formation of metallic glass from a molten liquid depends on whether cooling is sufficiently rapid to bypass crystallization and vitrify into an amorphous solid; for a given alloy composition, the ease with which full vitrification can occur upon cooling from the liquid state is termed the alloy's "glass forming ability". Unfortunately, relatively few excellent glass formers have been reported in the vast, multicomponent composition space in which they reside. The apparent slowness of progress may be attributed largely to the inefficiency of the one-at-a-time experimental approach to discovery and design. In this thesis work, a high-throughput combinatorial methodology was developed to expedite the discovery process of new bulk metallic glasses. Laser deposition was used to fabricate continuously-graded composition libraries of Cu-Zr and Cu-Zr-Ti alloys. By processing the libraries with a range of laser heat input, the best glass formers in each alloy system could be efficiently and systematically deduced. Furthermore, instrumented nanoindentation performed on the libraries enabled rapid evaluation of mechanical property trends. Despite boasting high strengths, monolithic bulk metallic glasses generally suffer from an intrinsic lack of damage tolerance compared to other high performance alloys

  12. Improvement of corrosion resistance in NaOH solution and glass forming ability of as-cast Mg-based bulk metallic glasses by microalloying

    Directory of Open Access Journals (Sweden)

    Peng Hao

    2011-02-01

    Full Text Available The influences of the addition of Ag on the glass forming ability (GFA and corrosion behavior were investigated in the Mg-Ni-based alloy system by X-ray diffraction (XRD and electrochemical polarization in 0.1 mol/L NaOH solution. Results shows that the GFA of the Mg-Ni-based BMGs can be improved dramatically by the addition of an appropriate amount of Ag; and the addition element Ag can improve the corrosion resistance of Mg-Ni-based bulk metallic glass. The large difference in atomic size and large negative mixing enthalpy in alloy system can contribute to the high GFA. The addition element Ag improves the forming speed and the stability of the passive film, which is helpful to decrease the passivation current density and to improve the corrosion resistance of Mg-Ni-based bulk metallic glass.

  13. Crystallization of Pd40CU30Ni10P20 bulk metallic glass with and without pressure

    DEFF Research Database (Denmark)

    Yang, B.; Jiang, Jianzhong; Zhuang, Yanxin;

    2007-01-01

    The glass-transition behavior of Pd40Cu30Ni10P20 bulk metallic glass was investigated by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The effect of pressure on the crystallization behavior of Pd40Cu30Ni10P20 bulk glass was studied by in situ high-pressure and high......-temperature X-ray powder diffraction using synchrotron radiation. Phase analyses show at least six crystalline phases in the crystallized sample, namely, monoclinic, tetragonal Cu3Pd-like, rhombohedral, fcc-Ni2Pd2P, fcc-(Ni, Pd) solid solution, and body-centered tetragonal (bct) Ni3P-like phases. The onset...... crystallization temperature increases with pressure having a slope of I I K/GPa in the range of 0 to 4 GPa. The results are attributed to the competing process between the thermodynamic potential barrier and the diffusion activation energy under pressure....

  14. Friction Stir Welding of Zr_(55)Al_(10)Ni_5Cu_(30) Bulk Metallic Glass to Crystalline Aluminum

    Institute of Scientific and Technical Information of China (English)

    Zuoxiang Qin; Cuihong Li; Haifeng Zhang; Zhongguang Wang; Zhuangqi Hu; Zhiqiang Liu

    2009-01-01

    The Zr_(55)Al_(10)Ni_5Cu_(30) bulk metallic glass plate were successfully welded to crystalline aluminum plates by using a friction stir welding (FSW) method. The welded zone was examined. No defects, cracks or pores were observed and no other crystalline phases except for aluminum were found in the welded joint. The strength of the joint is higher than that of aluminum. The glassy phase in the stir zone keeps the amorphous state, showing a successful welding. The storage modulus softens over the glass transition. And the weldability was discussed according to this phenomena.

  15. Mie Potential and Equation of State of Zr48Nb8Cu14Ni12Be18 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    张勇; 潘明祥; 汪卫华

    2001-01-01

    The linear expansion of Zr48Nb8Cu14Ni12Be18 bulk metallic glass (BMG) with excellent glass forming abilityand high thermal stability is investigated by a dilatometry method. The average expansion coefficient is αTG=1.04×10 -5 K-1 (300-656 K) for the BMG and αTC= 1.11×10 -5 K-1 (356~890 K) for the crystallized alloy.The Mie potential as well as the equation of state of the BMG and its corresponding crystallized state are determined from the thermal expansion and ultrasonic data, and the differences among them are phenomenologicallyexplained.

  16. A Combinatorial Approach to the Investigation of Metal Systems that Form Both Bulk Metallic Glasses and High Entropy Alloys

    Science.gov (United States)

    Welk, Brian A.; Gibson, Mark A.; Fraser, Hamish L.

    2016-03-01

    In this work, compositionally graded specimens were deposited using the laser engineered net-shaping (LENS™) additive manufacturing technique to study the glass-forming ability of two bulk metallic glass (BMG) and high entropy alloy (HEA) composite systems. The first graded specimen varied from Zr57Ti5Al10Cu20Ni8 (BMG) to CoCrFeNiCu0.5 (HEA) and the second graded specimen varied from TiZrCuNb (BMG) to (TiZrCuNb)65Ni35 (HEA). After deposition, laser surface melting experiments were performed parallel to the gradient to remelt and rapidly solidify the specimen. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to determine the morphology and composition variations in the as-deposited and laser surface melted phases. Selected area diffraction of the melt pool regions confirmed an almost fully amorphous region in the first gradient and an amorphous matrix/crystalline dendrite composite structure in the second gradient.

  17. Magnetic properties and microstructural homogeneity in NdFeAl bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Zempoalteca, R.; Valenzuela, R.; Betancourt, I. [Depto de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, UNAM, Avenida Universidad (Mexico)

    2011-11-15

    Bulk metallic glasses of nominal composition Nd{sub 60}Fe{sub 30}Al{sub 10} were prepared by copper mold casting in the form of rods of 3 mm in diameter and 50 mm in length. Preparation conditions were varied to assess the effects of the injection distance and the injection pressure of the melt. In order to determine their microstructure, disk-shaped samples were obtained from different cut zones along the axis rod. A non-homogeneous phase distribution was observed, which resulted from the heat transfer regime during the cooling of the melt in the copper mold. As expected, the nature, distribution and volumetric fraction of the various phases produced play an important role on the resulting magnetic properties. Among the main observed phases are Fe-rich rod-like crystals, Nd-rich dendritic crystals and a ''like-amorphous'' matrix. The hard magnetic properties of these materials can be associated with this matrix. In these cooling regimes, the coercive field increases as the cooling rate of the amorphous matrix increases. Hysteresis loops showed a high degree of coupling between phases with different magnetic order. Both the coercive field and the magnetization showed a significant variation along the rod axis; a maximum appeared as a function of the axis length. In order to gather more information about the coupling between the observed phases, {delta}M (or Henkel) plots were obtained, showing an exchange character for interactions (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Magnetic properties and power losses in Fe-Co-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Piccin, R. [Dip. Chim. IFM and NIS, Universita di Torino, Via P. Giuria 9, Torino 10125 (Italy)], E-mail: rafael.piccin@unito.it; Tiberto, P. [Electromagnetism Division, INRIM, Strade delle Cacce 91, Torino 10135 (Italy); Chiriac, H. [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., Iasi 700050 (Romania); Baricco, M. [Dip. Chim. IFM and NIS, Universita di Torino, Via P. Giuria 9, Torino 10125 (Italy)

    2008-10-15

    Magnetic properties of Fe-Co-based bulk metallic glasses have been experimentally investigated. Samples were prepared by water-cooled Cu-mold injection casting technique. The samples have cylindrical shapes with 0.8 mm diameter and 30 mm length. Amorphous structures were confirmed by the presence of a main halo in X-ray diffraction patterns and by the detection of crystallization signal around 650 deg. C using differential scanning calorimetry. Owing to their amorphous structure, these materials present good soft magnetic properties with coercivity below 100 A/m and magnetic induction around 1.0 T in quasi-static conditions. Hysteresis loops were measured using a digital wattmeter with controlled induction waveform. Power losses were analyzed for the following compositions: [(Fe{sub 1-x}Co{sub x}){sub 75}B{sub 20}Si{sub 5}]{sub 93}Nb{sub 4}Y{sub 3} (x=0, 0.2, 0.4, 0.5 and 0.6) over a range of frequencies from 1 to 400 Hz at selected fixed peak inductions. Co addition has shown to improve the soft magnetic properties when x=0.2, 0.4 and 0.5, decreasing coercive fields and power losses, while the magnetic induction is slightly increased (except for x=0.5). Further Co addition (x=0.6) is detrimental for the soft magnetic properties due to the presence of crystalline {alpha}-Fe-(Co) and boride phases. The frequency dependence of power losses was described using a separation theory. It has been observed that an f{sup 1/2} rule is in good agreement with the experimental data.

  19. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Du, Juan, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei [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, Zhejiang 315201 (China); Law, Jiayan [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  20. Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Wang; Zhenxi Guo; Rui Ma; Guojian Hao; Yong Zhang; Junpin Lin; Manling Sui

    2014-01-01

    The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass-matrix composite (MGMC) were investigated by using an in-situ tensile test under transmission electron microscopy (TEM). It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.

  1. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    Science.gov (United States)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  2. Viscosity properties and strong liquid behavior of Pr60Ni25Al15 bulk metallic glass-forming liquids

    Institute of Scientific and Technical Information of China (English)

    WANG Dan; ZHANG Di; WANG ShuYing; NING QianYan; ZHENG CaiPing; YAN Yuan; LIU Jia; SUN MinHua

    2008-01-01

    Pr60Ni25Al15 bulk metallic glass in a cuboid form with dimensions of 2 mm×2 mm×55 mm by copper mold casting method was cast.The dynamic viscosity near the glass transition region for Pr60Ni25Al15 was measured by three-point beam bending methods.The fragility parameter m and activation energy for viscous flow of the liquid sample were calculated to be: m = 31.66, E= 10689.17 K, respectively.It was shown that the supercooled liquid of Pr60Ni25Al15 alloy behaved much closer to strong glasses.The variation of active energy with temperature in supercooled liquid was analyzed.It was found that Kivelson's super-Arrhenius equation is not suitable for description of the activation energy in a supercooled region of Bulk metallic glass, and there is a direct proportion between activation energy crystal-lization and activation energy of viscous flow.

  3. Viscosity properties and strong liquid behavior of Pr60Ni25Al15 bulk metallic glass-forming liquids

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Pr60Ni25Al15 bulk metallic glass in a cuboid form with dimensions of 2 mm×2 mm×55 mm by copper mold casting method was cast. The dynamic viscosity near the glass transition region for Pr60Ni25Al15 was measured by three-point beam bending methods. The fragility parameter m and activation energy for viscous flow of the liquid sample were calculated to be:m=31.66,E=10689.17 K,respectively. It was shown that the supercooled liquid of Pr60Ni25Al15 alloy behaved much closer to strong glasses. The variation of active energy with temperature in supercooled liquid was analyzed. It was found that Kivelson’s super-Arrhenius equation is not suitable for description of the activation energy in a supercooled region of Bulk metallic glass,and there is a direct proportion between activation energy crystal-lization and activation energy of viscous flow.

  4. Microstructural Analysis of a Laser-Processed Zr-Based Bulk Metallic Glass

    Science.gov (United States)

    Sun, H.; Flores, K. M.

    2010-07-01

    Laser processing is a precision manufacturing technique capable of producing materials with highly nonequilibrium microstructures. Due to the localized heat input and high cooling rate inherent to the process, this technology is attractive for the production of metallic glasses. In the present work, we use a laser deposition process to deposit a Zr-based metallic glass forming powder on both amorphous and crystalline substrates of the same nominal composition. Amorphous melt zones are observed surrounded by distinct crystalline heat-affected zones (HAZs). Detailed examination of the HAZ in the glassy substrates reveals the formation of microscale spherulites, in contrast to the nanocrystalline phases observed following crystallization by isothermal annealing of the glass at the crystallization temperature as well as in the HAZ of the crystalline substrates. The spherulites have a different crystal morphology and structure from the nanocrystalline phases, indicating that the more stable nanocrystalline phases are completely bypassed when the glass is devitrified at the higher heating rate. Reducing the heat input during laser processing results in the near elimination of the crystalline HAZ in the amorphous substrates, suggesting that a critical heating rate range is required to avoid devitrification.

  5. Effect of Au Content on Thermal Stability and Mechanical Properties of Au-Cu-Ag-Si Bulk Metallic Glasses

    Science.gov (United States)

    Guo, H.; Zhang, W.; Chen, M. W.; Saotome, Y.; Fukuhara, M.; Inoue, A.

    2011-06-01

    The thermal stability, glass-forming ability (GFA), and mechanical and electrical properties of Au-based Au x Si17Cu75.5- x Ag7.5 ( x = 40 to 75.5 at. pct) metallic glasses were investigated. The glass transition temperature ( T g ) and crystallization temperature ( T x ) decreased with increasing Au content. The ultralow T g values below 373 K (100 °C) were obtained for alloys with x = 55 to 75.5. The alloys with x = 45 to 70 exhibited a high stabilization of supercooled liquid and a high GFA, and the supercooled liquid region and critical sample diameter for glass formation were in the range of 31 K to 50 K and 2 to 5 mm, respectively. The compressive fracture strength ( σ c,f ), Young's modulus ( E), and Vicker's hardness ( H v ) of the bulk metallic glasses (BMGs) decreased with increasing Au content. A linear correlation between Au concentration and the characteristic temperature, i.e., T g and T x , and mechanical properties, i.e., σ c,f , E, and H v , as well as electrical resistivity can be found in the BMGs, which will be helpful for the composition design of the desirable Au-based BMGs with tunable physical properties.

  6. Crystallization in Zr60Al15Ni25 bulk metallic glass subjected to rolling at room temperature

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The microstructure evolution of Zr60Al15Ni25 bulk metallic glass during rolling at room temperature is investigated by differential scanning calorimetry(DSC),high-resolution transmission electron microscopy(HRTEM) and selected area electronic diffraction(SAED).The HRTEM images show that shear bands are produced in the rolled specimens,indicating the essence of inhomogeneous deformation due to rolling,and that there exist nanocrystals with size of about 5-10 nm in the transition regions between the shear bands and the undeformed matrix in the rolled specimens with deformation degrees of 80% and 95%.Based on the polyhedral structure model and the shear transformation zone(STZ) theory,the influence of viscous flow,free volume,viscosity and the stress situation on the crystallization behaviors in the metallic glass during rolling is discussed.

  7. Structure and properties of Fe-Cr-Mo-C bulk metallic glasses obtained by die casting method

    Directory of Open Access Journals (Sweden)

    W. Pilarczyk

    2010-09-01

    Full Text Available urpose: The goal of this work is to investigate structure and properties of Fe54Cr16Mo12C18 alloy rods with different diameters obtained by the pressure die casting method.Design/methodology/approach: Master alloy ingot with compositions of Fe54Cr16Mo12C18 was prepared by induction melting of pure Fe, Cr, Mo, C elements in argon atmosphere. The investigated material were cast in form of rods with different diameters. Glassy and crystalline structures were examined by X-ray diffraction. The microscopic observation of the fracture morphology was carried out by the SEM with different magnification. The thermal properties of the studied alloy were examined by DTA and DSC method.Findings: These materials exhibit high glass-forming ability, excellent mechanical properties and corrosion resistance.Research limitations/implications: It is difficult to obtain a metallic glass of Fe54Cr16Mo12C18 alloy. The investigations carried out on the different samples of Fe54Cr16Mo12C18 bulk metallic alloy allowed to state that the studied ribbon was amorphous whereas rods were amorphous – crystalline.Originality/value: The formation and investigation of the casted Fe-Cr-Mo-C bulk materials and the study of glass-forming ability of this alloy.

  8. Free-volume evolution and its temperature dependence during rolling of Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.;

    2005-01-01

    The free-volume evolution during rolling Cu60Zr20Ti20 bulk metallic glass at room and cryogenic temperatures has been investigated by differential scanning calorimetry. When the specimen is rolled at cryogenic temperature, the free-volume content increases as the rolling proceeds first......, and then saturates accompanied by the occurrence of phase separation as the thickness reduction exceeds 89%. If the rolling is performed at room temperature, although the free-volume content also rises in the earlier stage, it tends to decrease rather than saturate when the thickness reduction exceeds 87...

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

    Directory of Open Access Journals (Sweden)

    Teruo Bitoh

    2015-06-01

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

  10. The Effect of Iron Content on Glass Forming Ability and Thermal Stability of Co–Fe–Ni–Ta–Nb–B–Si Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Aytekin Hitit

    2016-12-01

    Full Text Available In this study, change in glass forming ability (GFA and thermal stability of Co–Fe-based bulk metallic glasses were investigated as a function of iron content. Cylindrical samples of alloys with diameters of up to 4 mm were synthesized by a suction casting method in an arc furnace. Structures and thermal properties of the as-cast samples were determined by X-ray diffraction (XRD and differential scanning calorimetry (DSC, respectively. It was found that the critical casting thickness of the alloys reduced as iron content was increased and cobalt content was decreased. It was determined that GFA parameters, reduced glass transition temperature (Tg/Tl and δ (= Tx/(Tl − Tg, show a very good correlation with critical casting thickness values. It was also observed that changing iron content did not effect thermal properties of the alloys.

  11. On valence electron density, energy dissipation and plasticity of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pang, J.J.; Tan, M.J. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 639798 Singapore (Singapore); Liew, K.M., E-mail: kmliew@cityu.edu.hk [Department of Civil and Architectural Engineering, City University of Hong Kong, Kowloon (Hong Kong)

    2013-11-15

    Highlights: ► Relationship between valence electron density and plasticity of metallic glasses. ► Poisson's ratio increases as electron density decreases. ► Energy dissipation proposed to understand plasticity. ► Low electron density indicates small activation energy. -- Abstract: In conventional crystalline alloys, valence electron density (VED) is one of the most significant factors in determining their phase stability and mechanical properties. Extending the concept to metallic glasses (MGs), it is found, not totally surprisingly, that their mechanical properties are VED-dependent as in crystalline alloys. Interestingly, the whole VED region can be separated into two zones: Zone 1 consists of Mg-, Ca-, and RE-based (RE for rare earth) alloys; Zone 2 consists of the rest of MGs. In either zone, for each type of MGs, Poisson's ratio generally decreases as VED increases. From the energy dissipation viewpoint proposed recently, the amorphous plasticity is closely related to the activation energy for the operation of shear-transformation-zones (STZs). Smaller STZ activation energy suggests higher ductility because STZs with lower activation energy are able to convert deformation work more efficiently into configurational energy rather than heat, which yields mechanical softening and advances the growth of shear bands (SBs). Following this model, it is revealed that the activation energies for STZ operation and crystallization are certainly proportional to VED. Thus, it is understood that, in Zone 2, MGs have a smaller VED and hence lower activation energies which are favorable for ductility and Poisson's ratio. In Zone 1, MGs have the lowest VED but apparent brittleness because either of low glass transition temperature and poor resistance to oxidation or of a large fraction of covalent bonds.

  12. Enhanced Mechanical Properties of MgZnCa Bulk Metallic Glass Composites with Ti-Particle Dispersion

    Directory of Open Access Journals (Sweden)

    Pei Chun Wong

    2016-05-01

    Full Text Available Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf of Ti particles. The results showed that the compressive ductility increased with Vf. The mechanical performance of these BMGCs, with up to 5.4% compressive failure strain and 1187 MPa fracture strength at room temperature, can be obtained for the Mg-based BMGCs with 50 vol % Ti particles, suggesting that these dispersed Ti particles can absorb the energy of the crack propagations and can induce branches of the primary shear band into multiple secondary shear bands. It follows that further propagation of the shear band is blocked, enhancing the overall plasticity.

  13. Mechanical Property and Corrosion Resistance Evaluations of Ti-6Al-7Nb Alloy Brazed with Bulk Metallic Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E. [Nagasaki University, Nagasaki, Japan; Kato, H. [Tohoku University, Japan; Ogata, Toshiaki [Nagasaki University, Nagasaki, Japan; Nishiyama, Nobuyuki [Tohoku University, Japan; Specht, Eliot D [ORNL; Shiraishi, Takanobu [ORNL; Inoue, A. [Tohoku University, Japan; Hisatsune, K. [Nagasaki University, Nagasaki, Japan

    2007-01-01

    Exploitation of metallic glass as new brazing filler for Ti-based biomedical alloy was attempted. Ti-6Al-7Nb was used as a brazed material, and candidates of bulk metallic glass brazing filler were Cu60Hf25Ti15, Mg65Cu25Gd10, Zr55Cu30Al10Ni5 and Pd40Cu30P20Ni10. Convergence infrared-ray brazing was conducted for brazing Ti-6Al-7Nb/metallic glass in Ar atmosphere. After brazing, hardness measurement, X-ray tomography, cross-sectional observation, artificial saliva immersion test and tensile test were performed to evaluate brazability, mechanical property and corrosion resistance of the obtained brazing joints. The results of brazing using these metallic glass fillers show that all the metallic glasses were brazable to Ti-6Al-7Nb except for Mg65Cu25Gd10. Mg65Cu25Gd10, Cu60Hf25Ti15 and their joints collapsed rapidly during immersion test. Zr55Cu30Al10Ni5 joint was the best in terms of degradation resistance; however, tensile strength was inferior to the conventional one. Pd40Cu30Ni10P20 filler and Zr55Cu30Al10Ni5 filler and their joints did not show any collapse or tarnish during the immersion test. Pd40Cu30Ni10P20 joint showed the excellent properties in terms of both corrosion resistance and tensile strength, which were superior to a joint brazed using Ti-15Cu-25Ni conventional filler. X-ray tomograph indicates that fracture tends to occur in the vicinity of the brazing interface after tensile test. The brazed metallic glass fillers were fully crystallized, excluding Pd40Cu30Ni10P20 filler. Pd40Cu30Ni10P20 brazed filler contained mapleleaf like primary dendrite, peritectoid and a few microns interfacial reaction layer in glassy matrix. The results indicated that Pd40Cu30Ni10P20 is promising brazing filler for dental or biomaterial devices.

  14. Light Emission and Dynamic Failure Mechanism of Hypervelocity Impact on Zr-Ti-Ni-Cu-Be Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    SUN Bao-Ru; ZHAN Zai-Ji; LIANG Bo; ZHANG Rui-Jun; WANG Wen-Kui

    2011-01-01

    Hypervelocity impact on rectangular plate-shaped ZrnThtCuw.sNiioB^.s bulk metallic glass (BMG) is performed by a two-stage light gas gun. The targets used in the experiment are BMG plates with a thickness of 5 mm. The projectile, spherical aluminum (3.1 mm in diameter), is accelerated up to various velocities; the light is detected with a radiometer. The emission lasts from 200 \\is up to 1500 \\is and the intensity increases from 44 to 900 W/(Sr-\\im). The duration and intensity of a light emission seem to depend on the impact velocity and the extent of target destruction through the formation of impact craters or penetration.%@@ Hypervelocity impact on rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass(BMG)is per-formed by a two-stage light gas gun.The targets used in the experiment are BMG plates with a thickness of 5 mm.The projectile,spherical aluminum(3.1 mm in diameter),is accelerated up to various velocities;the light is detected with a radiometer.The emission lasts from 200μs up to 1500μs and the intensity increases from 44 extent of target destruction through the formation of impact craters or penetration.

  15. Looking for footprint of bulk metallic glass in electronic and phonon heat capacities of Cu55Hf45-xTix alloys

    Science.gov (United States)

    Remenyi, G.; Biljaković, K.; Starešinić, D.; Dominko, D.; Ristić, R.; Babić, E.; Figueroa, I. A.; Davies, H. A.

    2014-04-01

    We report on the heat capacity investigation of Cu55Hf45-xTix metallic glasses. The most appropriate procedure to estimate low temperature electronic and phonon contributions has been determined. Both contributions exhibit monotonous Ti concentration dependence, demonstrating that there is no relation of either the electron density of states at the Fermi level or the Debye temperature to the increased glass forming ability in the Ti concentration range x = 15-30. The thermodynamic parameters (e.g., reduced glass temperature) remain better indicators in assessing the best composition for bulk metallic glass formation.

  16. New Ti-based Ti–Cu–Zr–Fe–Sn–Si–Ag bulk metallic glass for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Shujie; Liu, Ying; Li, Haifei; Sun, Lulu [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Yan [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Zhang, Tao, E-mail: zhangtao@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-03-15

    Highlights: • Novel Ti{sub 47}Cu{sub 38}Zr{sub 7.5}Fe{sub 2.5}Sn{sub 2}Si{sub 1}Ag{sub 2} (at.%) bulk metallic glass (BMG) with a critical diameter of 7 mm was discovered. • The present BMG is the largest Ni- and Be-free Ti-based BMG containing low content of noble metal reported to date. • The glassy alloy possesses high specific strength, low Young’s modulus, and good corrosion resistance and bio-compatibility. • Combination of high glass-forming ability and good mechano- and bio-compatibility for the Ti-based BMG demonstrates the potential for use in biomedical applications. - Abstract: A novel Ni-free Ti{sub 47}Cu{sub 38}Zr{sub 7.5}Fe{sub 2.5}Sn{sub 2}Si{sub 1}Ag{sub 2} (at.%) bulk metallic glass (BMG) with superior glass-forming ability, good mechanical properties and excellent biocompatibility was discovered. The Ti-based BMG with a diameter of 7 mm can be prepared by copper mold casting and the supercooled liquid region was 52 K. Compressive strength, specific strength, Young’s modulus and microhardness of the Ti-based BMG were about 2.08 GPa, 3.2 × 10{sup 5} N m/kg, 100 GPa and 588 Hv, respectively. Electrochemical measurements indicated that the Ti-based glassy alloy possesses higher corrosion resistance than Ti–6Al–4V alloy in a simulated body fluid environment. Attachment, spreading out and proliferation of MC3T3-E1 cells on the Ti-based BMG surface demonstrated the excellent biocompatibility. Mechanisms of the formation and properties for the Ti-based glassy alloy are also discussed. The combination of high glass-forming ability, excellent mechanical properties, high corrosion resistance and good biocompatibility demonstrates the potential of the Ni-free Ti-based BMG for use in biomedical applications.

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

    Directory of Open Access Journals (Sweden)

    Tiburce A. Aboki

    2013-04-01

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

  18. Corrosion of Biocompatible Mg66+xZn30-xCa4 (x=0.2 Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Nowosielski R.

    2016-06-01

    Full Text Available The aim of this paper was to investigate the corrosion resistance of Mg66Zn30Ca4 and Mg68Zn28Ca4 metallic glasses and evaluate the ability of this amorphous alloy use for medical applications as biodegradable medical implants. Taking into account the amount of Mg, Zn, Ca elements dissolved in multielectrolyte physiological fluid (MPF from Mg66+xZn30-xCa4 (x=0.2 alloys the daily dose of evolved ions from alloys components was determined. Additional goal of the paper was determination of corrosion rate (Vcorr and amount of hydrogen evolved from amorphous magnesium alloys in simulated environment of human body fluids during 24h immersion and during electrochemical tests. Corrosion studies were done in the multielectrolyte physiological fluid (MPF at 37°C. The amount of hydrogen evolved [ml/cm2] and corrosion rate Vcorr [mm/year] of amorphous Mg66Zn30Ca4 and Mg68Zn28Ca4 alloys were compared. The work also presents characterization of Mg-based bulk metallic glasses structure in the form of 2 mm thickness plates. Samples structure was analyzed by means of X-ray diffraction. Fracture and surface morphology of magnesium alloy samples were identified using scanning electron microscopy.

  19. Dry Sliding Wear Behavior of Spark Plasma Sintered Fe-Based Bulk Metallic Glass/Graphite Composites

    Directory of Open Access Journals (Sweden)

    Xiulin Ji

    2016-09-01

    Full Text Available Bulk metallic glass (BMG and BMG-graphite composites were fabricated using spark plasma sintering at the sintering temperature of 575 °C and holding time of 15 min. The sintered composites exhibited partial crystallization and the presence of distributed porosity and graphite particles. The effect of graphite reinforcement on the tribological properties of the BMG/graphite composites was investigated using dry ball-on-disc sliding wear tests. The reinforcement of graphite resulted in a reduction in both the wear rate and the coefficient of friction as compared to monolithic BMG samples. The wear surfaces of BMG/graphite composites showed regions of localized wear loss due to microcracking and fracture, as was also the case with the regions covered with graphite-rich protective film due to smearing of pulled off graphite particles.

  20. Second amorphous-to-crystalline phase transformation in Cu60Ti20Zr20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhang, P.N.;

    2007-01-01

    The second amorphous-to-crystalline phase transformation in Cu60Ti20Zr20 bulk metallic glass was investigated by differential scanning calorimetry and x-ray diffractometry. The difference of the Gibbs free energies between the amorphous phase and the crystalline products during the transformation...... is estimated to be about 2.46 kJ mol(-1) at 753 K, much smaller than the 61 kJ mol(-1) obtained assuming that it is a polymorphic transformation. It was revealed that the phase transformation occurs through a eutectic crystallization of Cu51Zr14 and Cu2TiZr14 having an effective activation energy of the order...... of 400 kJ mol(-1). The average Avrami exponent n is about 2.0, indicating that the crystallization is diffusion controlled....

  1. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Directory of Open Access Journals (Sweden)

    K. K. Song

    2013-01-01

    Full Text Available The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-“double”-to-“triple”-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  2. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Science.gov (United States)

    Song, K. K.; Pauly, S.; Sun, B. A.; Tan, J.; Stoica, M.; Kühn, U.; Eckert, J.

    2013-01-01

    The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-"double"-to-"triple"-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  3. Light Emission and Dynamic Failure Mechanism of Hypervelocity Impact on Zr-Ti-Ni-Cu-Be Bulk Metallic Glass

    Science.gov (United States)

    Sun, Bao-Ru; Zhan, Zai-Ji; Liang, Bo; Zhang, Rui-Jun; Wang, Wen-Kui

    2011-09-01

    Hypervelocity impact on rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is performed by a two-stage light gas gun. The targets used in the experiment are BMG plates with a thickness of 5 mm. The projectile, spherical aluminum (3.1 mm in diameter), is accelerated up to various velocities; the light is detected with a radiometer. The emission lasts from 200 μs up to 1500 μs and the intensity increases from 44 to 900 W/(Sr·μm). The duration and intensity of a light emission seem to depend on the impact velocity and the extent of target destruction through the formation of impact craters or penetration.

  4. Numerical Study of the Effect of the Sample Aspect Ratio on the Ductility of Bulk Metallic Glasses (BMGs) Under Compression

    Science.gov (United States)

    Jiang, Yunpeng

    2016-05-01

    In this article, a systematic numerical study was conducted to study the detailed shear banding evolution in bulk metallic glasses (BMGs) with various sample aspect ratios under uniaxial compression, and whereby the effect of the sample aspect ratio on the compressive ductility was elucidated. A finite strain viscoelastic model was employed to describe the shear banding nucleation, growth, and coalescence in BMG samples with the help of Anand and Su's theory, which was incorporated into the ABAQUS finite element method code as a user material subroutine VUMAT. The present numerical method was first verified by comparing with the corresponding experimental results, and then parameter analysis was performed to discuss the impact of microstructure parameters on the predicted results. The present modeling will shed some light on enhancing the toughness of BMG structures in the engineering applications.

  5. On the mechanically induced crystallization of FCC phases by mechanical milling in ZrAlNiCu bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Grosdidier, Thierry, E-mail: grosdidier@letam.sciences.univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Allain-Bonasso, Nathalie [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Gaffet, Eric [Nanomaterials Research Group (NRG, UMR CNRS 5060), Site de Sevenans (UTBM), F90010 Belfort Cedex (France); Dong, Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China)

    2010-08-15

    In the present study, amorphous-nanocrystalline phase transformation induced by mechanical milling of full monolithic bulk metallic glasses (based on Zr{sub 65}Al{sub 7.5}Ni{sub 10}Cu{sub 17.5} and Zr{sub 58}Al{sub 16}Ni{sub 11}Cu{sub 15} alloys) has been investigated using X-ray diffraction as well as transmission electron microscopy. Nanocrystals having an FCC structure and a grain size of several 10 nm precipitate in the early stages of the milling process and remain stable for long milling duration. The structure changes induced by milling give a new insight on the preparation of amorphous-related alloys when using the method of mechanical milling.

  6. CHARACTERIZATION OF PLASTICALLY-INDUCED STRUCTURAL CHANGES IN A Zr-BASED BULK METALLIC GLASS USING POSITRON ANNIHILATION SPECTROCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Flores, K M; Kanungo, B P; Glade, S C; Asoka-Kumar, P

    2005-09-16

    Flow in metallic glasses is associated with stress-induced cooperative rearrangements of small groups of atoms involving the surrounding free volume. Understanding the details of these rearrangements therefore requires knowledge of the amount and distribution of the free volume and how that distribution evolves with deformation. The present study employs positron annihilation spectroscopy to investigate the free volume change in Zr{sub 58.5}Cu{sub 15.6}Ni{sub 12.8}Al{sub 10.3}Nb{sub 2.8} bulk metallic glass after inhomogeneous plastic deformation by cold rolling and structural relaxation by annealing. Results indicate that the size distribution of open volume sites is at least bimodal. The size and concentration of the larger group, identified as flow defects, changes with processing. Following initial plastic deformation the size of the flow defects increases, consistent with the free volume theory for flow. Following more extensive deformation, however, the size distribution of the positron traps shifts, with much larger open volume sites forming at the expense of the flow defects. This suggests that a critical strain is required for flow defects to coalesce and form more stable nanovoids, which have been observed elsewhere by high resolution TEM. Although these results suggest the presence of three distinct open volume size groups, further analysis indicates that all groups have the same line shape parameter. This is in contrast to the distinctly different interactions observed in crystalline materials with multiple defect types. This similarity may be due to the disordered structure of the glass and positron affinity to particular atoms surrounding open-volume regions.

  7. Influence of Cu content on the mechanical properties and corrosion resistance of Mg-Zn-Ca bulk metallic glasses

    Science.gov (United States)

    Zhao, Yan-feng; Zhu, Jian; Chang, Li; Song, Jing-guo; Chen, Xiao-hua; Hui, Xi-dong

    2014-05-01

    (Mg66.2Zn28.8Ca5)100- x Cu x (at%, x = 0, 1, 3, and 5) bulk metallic glasses (BMGs) of 2 mm in diameter were prepared by the conventional copper mold injection casting method. Besides, the influence of Cu content on the microstructure, thermal stability, mechanical properties, and corrosion behavior of Mg-Zn-Ca BMGs was investigated. It is found that the addition of Cu decreases the glass-forming ability of Mg-Zn-Ca BMGs. Crystalline phases are precipitated at a higher Cu content, larger than 3at%. The compressive fracture strength of Mg-Zn-Ca BMGs is enhanced by the addition of Cu. With the formation of in-situ composites, the compressive strength of the Mg-Zn-Ca alloy with 3at% Cu reaches 979 MPa, which is the highest strength among the Mg-Zn-Ca alloys. Furthermore, the addition of Cu also results in the increase of corrosion potential and the decrease of corrosion current density in Mg-Zn-Ca BMGs, thereby delaying their biodegradability.

  8. In situ synthesis of TiC reinforced Cu47Ti34Zr11Ni8 bulk metallic glass composites

    Institute of Scientific and Technical Information of China (English)

    SUN Yufeng; ZHANG Guosheng; WEI Bingchen; LI Weihuo; WANG Yuren

    2004-01-01

    In situ synthesized TiC particles and β-Ti dendrites reinforced Cu47Ti34Zr11 Ni8 bulk metallic glass (BMG)composite ingots were prepared by the suction casting method. The ingots with diameters from 1 up to 4 mm were successfully obtained. It was shown that introducing TiC micro-sized particles into the amorphous matrix did not disturb the glass forming ability (GFA) of the matrix, while the yield strength and ductility could be well improved. The phase constitution, microstructure and elements distribution in the composites were studied by OM, XRD, SEM and EDS.It was shown that the in situ synthesized TiC particles acting as heterogeneous nucleation sites promoted the precipitation of β-Ti dendrites, resulting in the formation of the TiC particles and β-Ti dendrites co-reinforced BMG composites. The compressive tests were employed to probe the yield strength and ductility of BMG composites.

  9. Isoconfigurational elastic constants and liquid fragility of a bulk metallic glass forming alloy.

    Science.gov (United States)

    Lind, Mary Laura; Duan, Gang; Johnson, William L

    2006-07-07

    Samples of Zr(46.25)Ti(8.25)Cu(7.5)Ni(10)Be(27.5) were isothermally annealed and quenched near the glass transition temperature and studied by the pulse-echo overlap technique. The shear modulus G of the samples shows a strong reversible dependence on annealing temperatures and, thus, on the specific configurational potential energy of the equilibrium liquid. The low-T dependence of G of the configurationally frozen glasses shows linear temperature dependence as expected by Debye-Grüneisen theory. The T dependence of G in the liquid state is directly related to the viscosity and fragility of the liquid.

  10. Effect of incongruent crystallization on glass–liquid transition features of a bulk metal glass

    Energy Technology Data Exchange (ETDEWEB)

    Aji, D.P.B.; Johari, G.P., E-mail: joharig@mcmaster.ca

    2015-09-10

    Highlights: • Ce{sub 66}Al{sub 10}Cu{sub 20}Co{sub 4} glass did not crystallize during aging for nine years. • Crystallization's onset temperature was higher for the aged glass. • Incongruent melt embedding the crystals had higher viscosity and T{sub g}. • Increase in crystallization increased the T{sub g} and broadened the T{sub g}-endotherm. - Abstract: It is known that most multi-component glasses cold-crystallize incongruently on heating through the temperature range of their ultraviscous melt. If the incongruent melt's composition changes with time, its viscosity, η, and the glass–liquid transition temperature, T{sub g}, would change. Since the η, relaxation time, and expansion coefficient of a liquid in its partially crystallized mixture cannot be determined, we used scanning calorimetry to study the liquid–glass–liquid transition during thermal cycling of the incongruently crystallizing Ce{sub 66}Al{sub 10}Cu{sub 20}Co{sub 4} glass. Its T{sub g} is 358 K for 20 K/min and 354 K for 10 K/min heating rates, and its ultraviscous melt crystallized incongruently when heated beyond the hysteresis peak of its heat capacity scan. Its sample that had been aged for nine years at ambient conditions had a higher crystallization-onset temperature than an un-aged sample. Delayed enthalpy gain on heating of the aged glass is ∼1/5th of the enthalpy lost on its crystallization. Crystallization of the melt occurred on both the heating and cooling paths of a thermal cycle and T{sub g} of the un-aged glass increased as the volume fraction of the compositionally different glass, f{sub gl}, decreased. The increase was by 8 K after the 24th cycle of 20 K/min, and by 11 K after the 13th cycle of 10 K/min cooling-heating. The highest T{sub g} values reached differed by ∼1 K, which indicates that closely similar T{sub g}s may be reached if the total time period for thermal cycling (at different rates) is kept the same. As f{sub gl} approached its limiting

  11. Evaluation of Ni-free Zr–Cu–Fe–Al bulk metallic glass for biomedical implant applications

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ying-Sui [Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Zhang, Wei [School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); Kai, Wu [Institute of Materials Engineering, National Taiwan Ocean University, Keelung, Taiwan (China); Liaw, Peter K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN (United States); Huang, Her-Hsiung, E-mail: hhhuang@ym.edu.tw [Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan (China)

    2014-02-15

    Highlights: ► A Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} bulk metallic glass (BMG) with 50 GPa elastic modulus was used. ► This Ni-free Zr-based BMG had lower metal ion release rate than the commercial Ti. ► This Ni-free Zr-based BMG had better proteins adsorption than the commercial Ti. ► This Ni-free Zr-based BMG has a high potential for biomedical implant applications. -- Abstract: This study was conducted to investigate the surface characteristics, including the chemical composition, metal ion release, protein adsorption, and cell adhesion, of a Ni-free Zr-based (Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10}) bulk metallic glass (BMG) with low elastic modulus for biomedical implant applications. X-ray photoelectron spectroscopy was used to identify the surface chemical composition and the protein (albumin and fibronectin) adsorption of the specimen. The metal ions released from the specimen in simulated blood plasma and artificial saliva solutions were measured using an inductively coupled plasma-mass spectrometer. The cell adhesion, in terms of the morphology, focal adhesion complex, and skeletal arrangement, of human bone marrow mesenchymal stem cells was evaluated using scanning electron microscope observations and immunofluorescent staining. For comparison purposes, the above-mentioned tests were also carried out on the widely used biomedical metal, Ti. The results showed that the main component on the outermost surface of the amorphous Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG was ZrO{sub 2} with small amounts of Cu, Al, and Fe oxides. The released metal ions from Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG were well below the critical concentrations that cause negative biological effects. The Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG had a greater adsorption capacity for albumin and fibronectin than that of commercial biomedical Ti. The Zr{sub 62.5}Cu{sub 22.5}Fe{sub 5}Al{sub 10} BMG surface showed an attached cell number similar

  12. 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.

  13. Pressure effect of glass transition temperature in Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk metallic glass

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Roseker, W.; Sikorski, M.;

    2004-01-01

    Pressure effects on glass transition temperature and supercooled liquid region of a Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass have been investigated by performing in situ high-temperature and high-pressure x-ray powder diffraction measurements using synchrotron radiation. The glass transition was det...... range of 0-2.2 GPa. This method opens a possibility to study the pressure effect of glass transition process in glassy systems under high pressures (>1 GPa). (C) 2004 American Institute of Physics....

  14. Analysis of the Influence of Element's Entropy on the Bulk Metallic Glass (BMG) Entropy, Complexity, and Strength

    Science.gov (United States)

    Namazi, Hamidreza; Akrami, Amin; Haghighi, Reza; Delaviz, Ali; Kulish, Vladimir V.

    2017-02-01

    Bulk metallic glasses (BMGs) are disordered compounds without a long-range crystalline order. In this paper, we study the effect of an element's standard entropy on the BMG's entropy and complexity for four elements. In order to do this, we simulate the BMG structures first. Then we compute the entropy and fractal dimension of the resulting structures as measures of disorder and complexity, respectively. We verify our predictions via experiments. In doing so, we substitute the elements in separate experiments and compute the fractal dimension of the obtained BMG pattern. The results of our investigations show that there is a relation between the variations of elements' entropies and the variations of BMGs' entropy and fractality. On the other hand, measurement of the compressive strength for the obtained BMGs from experiments shows that by increasing the entropy and fractal dimension, BMG's compressive strength increases. The adaptive capability observed in this method could potentially be harnessed for targeted BMG production, depending on the specific design goal. The method discussed here is not only useful for analysis of BMG structures, but it can be applied to other structures.

  15. Relation between icosahedral short-range ordering and plastic deformation in Zr-Nb-Cu-Ni-Al bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Z.W. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Gu, L. [WPI, Advance Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Xie, G.Q. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Zhang, W., E-mail: wzhang@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [WPI, Advance Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Zhang, H.F., E-mail: hfzhang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Hu, Z.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-04-15

    The relation between icosahedral short-range ordering (ISRO) and plastic deformation was investigated in Zr{sub 70-x}Nb{sub x}Cu{sub 13.5}Ni{sub 8.5}Al{sub 8} (at.%, x = 0, 2, 4, 6, 7, 8, 10) bulk metallic glasses (BMG). The formation of icosahedral quasicrystal (I-phase) during the annealing process implies that ISRO widely exists in these materials. The degree of ISRO is thermodynamically evaluated to show that ISRO increases with increasing Nb content. Compression tests indicate that BMG with 0-7 at.% Nb possess similar unusual plastic deformability, which is attributed to ISRO-mediated local distribution of free volume (FV) and ISRO prompted deformation-induced crystallization. A proposed core-shell model coupled with transmission electron microscopy analysis demonstrates that the FV is distributed more heterogeneously with increasing ISRO, which is beneficial for multiplying the shear bands. Deformation-induced crystallization is facilitated, owing to the low interfacial energy of the nucleation and growth of the crystals attributed to ISRO in the amorphous matrix, which improves plasticity by consuming energy and the product altering the stress field in the amorphous matrix. Design of new ductile BMG is discussed in these strategies.

  16. Comparative study of bulk metallic glass composites with high-volume-fractioned dendritic and spherical b. c. c. phase precipitates

    Directory of Open Access Journals (Sweden)

    Guo-yuan Sun

    2015-05-01

    Full Text Available A dendritic β-phase reinforced bulk metallic glass (BMG composite named as D2 was prepared by rapid quenching of a homogenous Zr60Ti14.67Nb5.33Cu5.56Ni4.44Be10 melt, and characterized by means of X-ray diffraction (XRD, scanning electron microscopy (SEM observation and room-temperature compression test. The microstructure and mechanical properties were compared with those of the spherical β-phase reinforced composite named as composite S2. It was found that the composite D2 contains β-phase dendrites up to 56% in volume-fraction, and exhibits a ductile compressive behavior with plastic strain of 12.7%. As the high-volume-fractioned β-phase dendrites transferred to coarse spherical particles of about 20 μm in diameter in the composite S2, a much improved plastic strain up to 20.4% can be achieved. Micrographs of the fractured samples reveal different interaction modes of the propagating shear bands with the dendritic and spherical β phase inclusions, resulting in different shear strains in the composite samples. The matrix of composite S2 undergoes a significantly larger shear strain than that of the composite D2 before ultimate failure, which is thought to be mainly responsible for the greatly increased global plastic strain of the S2 relative to D2.

  17. Studies of Shear Band Velocity Using Spatially and Temporally Resolved Measurements of Strain During Quasistatic Compression of Bulk Metallic Glass

    Energy Technology Data Exchange (ETDEWEB)

    Wright, W J; Samale, M; Hufnagel, T; LeBlanc, M; Florando, J

    2009-06-15

    We have made measurements of the temporal and spatial features of the evolution of strain during the serrated flow of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass tested under quasistatic, room temperature, uniaxial compression. Strain and load data were acquired at rates of up to 400 kHz using strain gages affixed to all four sides of the specimen and a piezoelectric load cell located near the specimen. Calculation of the displacement rate requires an assumption about the nature of the shear displacement. If one assumes that the entire shear plane displaces simultaneously, the displacement rate is approximately 0.002 m/s. If instead one assumes that the displacement occurs as a localized propagating front, the velocity of the front is approximately 2.8 m/s. In either case, the velocity is orders of magnitude less than the shear wave speed ({approx}2000 m/s). The significance of these measurements for estimates of heating in shear bands is discussed.

  18. Specimen Size Effects on Zr-Based Bulk Metallic Glasses Investigated by Uniaxial Compression and Spherical Nanoindentation

    Science.gov (United States)

    Bei, H.; Lu, Z. P.; Shim, S.; Chen, G.; George, E. P.

    2010-07-01

    Specimen size effects on the mechanical behavior of Zr-based bulk metallic glasses (BMGs) were investigated by compression and nanoindentation tests. In compression, even at the 1- to 10-mm scale, stable shear band propagation and extensive plastic deformation can be achieved in small (2 mm) specimens, in contrast to large (6.5 mm) specimens, which fail catastrophically after limited plastic deformation. The yield strength is independent of specimen size in this range, and plastic deformation remains highly localized in a few shear bands even in those specimens that exhibit stable shear sliding. The fracture surfaces of small specimens are smooth, without the vein patterns normally observed as characteristic features on the fracture surfaces of BMGs. During spherical nanoindentation, it is found that the upper bound of the maximum shear stress to initiate plasticity (yielding) in a Zr-based BMG is almost constant for indenter radii smaller than ~90 µm. However, the lower bound of this maximum shear stress decreases with increasing indenter radius, probably due to the increased probability of finding defects underneath larger indenters.

  19. Effect of Annealing Treatment on Erosion-Corrosion of Zr-Based Bulk Metallic Glass in Saline-Sand Slurry

    Science.gov (United States)

    Ji, Xiulin; Shan, Yiping; Chen, Yueyue; Wang, Hui

    2016-06-01

    Bulk metallic glass (BMG) may be a good candidate to solve the erosion-corrosion (E-C) problems of marine pumps in sand-containing seawater. Since annealing treatment is an effective way to improve plasticity of BMGs, the effect of annealing treatment on E-C wear of Zr-based BMG in saline-sand slurry was investigated. All of the annealed BMG samples were crystallized and the quantity of (Zr, Cu) phase increased but that of Al4Cu9 phase decreased with the increase of annealing temperature from 360 to 480 °C. Accordingly, annealing treatment enhances plasticity of the as-cast BMG at the cost of hardness and corrosion resistance. Moreover, 480 °C annealed BMG sample possesses the highest hardness and the lowest corrosion current density in all of the annealed BMG samples. Using a slurry pot erosion tester, the E-C wear of the as-cast and annealed BMG samples was studied under different impingement angles, impact velocities, and concentrations in saline-sand slurry. With the improvement of plasticity, 480 °C annealed BMG sample exhibits the best E-C wear resistance under high impingement angle, high impact velocity, and high sand concentration.

  20. Direct Observation on the Evolution of Shear Banding and Buckling in Tungsten Fiber Reinforced Zr-Based Bulk Metallic Glass Composite

    Science.gov (United States)

    Chen, J. H.; Chen, Y.; Jiang, M. Q.; Chen, X. W.; Fu, H. M.; Zhang, H. F.; Dai, L. H.

    2014-11-01

    The evolution of micro-damage and deformation of each phase in the composite plays a pivotal role in the clarification of deformation mechanism of composite. However, limited model and mechanical experiments were conducted to reveal the evolution of the deformation of the two phases in the tungsten fiber reinforced Zr-based bulk metallic glass composite. In this study, quasi-static compressive tests were performed on this composite. For the first time, the evolution of micro-damage and deformation of the two phases in this composite, i.e., shear banding of the metallic glass matrix and buckling deformation of the tungsten fiber, were investigated systematically by controlling the loading process at different degrees of deformation. It is found that under uniaxial compression, buckling of the tungsten fiber occurs first, while the metallic glass matrix deforms homogeneously. Upon further loading, shear bands initiate from the fiber/matrix interface and propagate in the metallic glass matrix. Finally, the composite fractures in a mixed mode, with splitting in the tungsten fiber, along with shear fracture in the metallic glass matrix. Through the analysis on the stress state in the composite and resistance to shear banding of the two phases during compressive deformation, the possible deformation mechanism of the composite is unveiled. The deformation map of the composite, which covers from elastic deformation to final fracture, is obtained as well.

  1. Mapping strain fields induced in Zr-based bulk metallic glasses during in-situ nanoindentation by X-ray nanodiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gamcová, J.; Bednarčík, J.; Franz, H. [DESY, Notkestraße 85, Hamburg 22547 (Germany); Mohanty, G.; Wehrs, J.; Michler, J. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstraße 39, Thun 3602 (Switzerland); Michalik, Š. [Institute of Physics ASCR, Na Slovance 2, Praha 18221 (Czech Republic); Krywka, C. [HZG, Institut für Werkstoffforschung, Notkestraße 85, Hamburg 22547 (Germany); Breguet, J. M. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstraße 39, Thun 3602 (Switzerland); Alemnis GmbH, Feuerwerkerstraße 39, Thun 3602 (Switzerland)

    2016-01-18

    A pioneer in-situ synchrotron X-ray nanodiffraction approach for characterization and visualization of strain fields induced by nanoindentation in amorphous materials is introduced. In-situ nanoindentation experiments were performed in transmission mode using a monochromatic and highly focused sub-micron X-ray beam on 40 μm thick Zr-based bulk metallic glass under two loading conditions. Spatially resolved X-ray diffraction scans in the deformed volume of Zr-based bulk metallic glass covering an area of 40 × 40 μm{sup 2} beneath the pyramidal indenter revealed two-dimensional map of elastic strains. The largest value of compressive elastic strain calculated from diffraction data at 1 N load was −0.65%. The region of high elastic compressive strains (<−0.3%) is located beneath the indenter tip and has radius of 7 μm.

  2. Influence of the Ag concentration on the medium-range order in a CuZrAlAg bulk metallic glass

    Science.gov (United States)

    Gammer, C.; Escher, B.; Ebner, C.; Minor, A. M.; Karnthaler, H. P.; Eckert, J.; Pauly, S.; Rentenberger, C.

    2017-03-01

    Fluctuation electron microscopy of bulk metallic glasses of CuZrAl(Ag) demonstrates that medium-range order is sensitive to minor compositional changes. By analyzing nanodiffraction patterns medium-range order is detected with crystal-like motifs based on the B2 CuZr structure and its distorted structures resembling the martensitic ones. This result demonstrates some structural homology between the metallic glass and its high temperature crystalline phase. The amount of medium-range order seems slightly affected with increasing Ag concentration (0, 2, 5 at.%) but the structural motifs of the medium-range ordered clusters become more diverse at the highest Ag concentration. The decrease of dominant clusters is consistent with the destabilization of the B2 structure measured by calorimetry and accounts for the increased glass-forming ability.

  3. Short-to-Medium-Range Order and Atomic Packing in Zr48Cu36Ag8Al8 Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Yong Xu

    2016-10-01

    Full Text Available Due to its excellent glass-forming ability (GFA, the Zr48Cu36Al8Ag8 bulk metallic glass (BMG is of great importance in glass transition investigations and new materials development. However, due to the lack of detailed structural information, the local structure and atomic packing of this alloy is still unknown. In this work, synchrotron measurement and reverse Monte Carlo simulation are performed on the atomic configuration of a Zr-based bulk metallic glass. The local structure is characterized in terms of bond pairs and Voronoi tessellation. It is found that there are mainly two types of bond pairs in the configuration, as the body-centered cubic (bcc-type and icosahedral (ico-type bond pairs. On the other hand, the main polyhedra in the configuration are icosahedra and the bcc structure. That is, the bcc-type bond pairs, together with the ico-type bond pairs, form the bcc polyhedra, introducing the distortion in bcc clusters in short range. However, in the medium range, the atoms formed linear or planar structures, other than the tridimensional clusters. That is, the medium-range order in glass is of 1D or 2D structure, suggesting the imperfect ordered packing feature.

  4. Dynamic behaviors of a Zr-based bulk metallic glass under ramp wave and shock wave loading

    Directory of Open Access Journals (Sweden)

    Binqiang Luo

    2015-06-01

    Full Text Available Dynamic behaviors of Zr51Ti5Ni10Cu25Al9 bulk metallic glass were investigated using electric gun and magnetically driven isentropic compression device which provide shock and ramp wave loading respectively. Double-wave structure was observed under shock compression while three-wave structure was observed under ramp compression in 0 ∼ 18GPa. The HEL of Zr51Ti5Ni10Cu25Al9 is 8.97 ± 0.61GPa and IEL is 8.8 ± 0.3GPa, respectively. Strength of Zr51Ti5Ni10Cu25Al9 estimated from HEL is 5.0 ± 0.3GPa while the strength estimated from IEL is 3.6 ± 0.1GPa. Shock wave velocity versus particle velocity curve of Zr51Ti5Ni10Cu25Al9 under shock compression appears to be bilinear and a kink appears at about 18GPa. The Lagrangian sound speed versus particle velocity curve of Zr51Ti5Ni10Cu25Al9 under ramp wave compression exhibits two discontinuances and are divided to three regions: elastic, plastic-I and plastic-II. The first jump-down occurs at elastic-plastic transition and the second appears at about 17GPa. In elastic and plastic-I regions, Lagrangian sound speed increases linearly with particle velocity, respectively. Characteristic response of sound speed in plastic-I region disagree with shock result in the same pressure region(7GPa ∼ 18GPa, but is consistent with shock result at higher pressure(18-110GPa.

  5. Evolution of shear bands, free volume, and structure in room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuanli; Shi, Bo; Ma, Zhikun; Li, Jiangong, E-mail: lijg@lzu.edu.cn

    2015-01-19

    The evolution of the shear band, free volume, and structure in room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass was investigated. It was found that the average shear band density increases monotonously with increasing strain. For the room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass with a strain of 99%, a high density of shear bands with an average spacing of 31 nm was observed. The absolute free volume content was determined based on the free volume model and found to increase monotonously with increasing strain. The free volume content in the room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass with a strain of 99% is 34% higher than its as-cast counterpart. Neither phase separation nor crystallization occurs in all the deformed samples. The coordination number of the first coordination shell decreases and the degree of disorder of atomic arrangement increases with increasing strain.

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

    Directory of Open Access Journals (Sweden)

    S. Lesz

    2016-01-01

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

  7. The effect of Nb addition on mechanical properties, corrosion behavior, and metal-ion release of ZrAlCuNi bulk metallic glasses in artificial body fluid.

    Science.gov (United States)

    Qiu, C L; Liu, L; Sun, M; Zhang, S M

    2005-12-15

    Bulk metallic glasses (BMGs) of Zr(65 - x)Nb(x)- Cu(17.5)Ni(10)Al(7.5) with Nb = 0, 2, and 5 at % were prepared by copper mold casting. Compression tests reveal that the two BMGs containing Nb exhibited superior strength and plasticity to the base alloy. The corrosion behavior of the alloys obtained was investigated in artificial body fluid by electrochemical measurements. It was found that the addition of Nb significantly enhanced the corrosion resistance of the Zr-based BMG, as indicated by a remarkable increase in corrosion potential and pitting potential. XPS analysis revealed that the passive film formed after anodic polarization was enriched in aluminum oxide and depleted in phosphate ions for the BMGs containing Nb, which accounts for the improvement of corrosion resistance. On the other hand, metal-ion release of different BMGs were determined in PPb (ng/mL) level with inductively coupled plasma mass spectrometry (ICP-MS) after being immersed in artificial body fluid at 37 degrees C for 20 days. It was found that the addition of Nb considerably reduced the ion release of all kinds of metals of the base system. This is probably attributed to the promoting effect of Nb on a rapid formation of highly protective film.

  8. Surface engineering of a Zr-based bulk metallic glass with low energy Ar- or Ca-ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lu; Zhu, Chao [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); Muntele, Claudiu I. [Center for Irradiation Materials, Alabama A and M University, P. O. Box 1447, Normal, AL 35762 (United States); Zhang, Tao [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Department of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Liaw, Peter K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); He, Wei, E-mail: whe5@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996-2210 (United States)

    2015-02-01

    In the present study, low energy ion implantation was employed to engineer the surface of a Zr-based bulk metallic glass (BMG), aiming at improving the biocompatibility and imparting bioactivity to the surface. Ca- or Ar-ions were implanted at 10 or 50 keV at a fluence of 8 × 10{sup 15} ions/cm{sup 2} to (Zr{sub 0.55}Al{sub 0.10}Ni{sub 0.05}Cu{sub 0.30}){sub 99}Y{sub 1} (at.%) BMG. The effects of ion implantation on material properties and subsequent cellular responses were investigated. Both Ar- and Ca-ion implantations were suggested to induce atom displacements on the surfaces according to the Monte-Carlo simulation. The change of atomic environment of Zr in the surface regions as implied by the alteration in X-ray absorption measurements at Zr K-edge. X-ray photoelectron spectroscopy revealed that the ion implantation process has modified the surface chemical compositions and indicated the presence of Ca after Ca-ion implantation. The surface nanohardness has been enhanced by implantation of either ion species, with Ca-ion implantation showing more prominent effect. The BMG surfaces were altered to be more hydrophobic after ion implantation, which can be attributed to the reduced amount of hydroxyl groups on the implanted surfaces. Higher numbers of adherent cells were found on Ar- and Ca-ion implanted samples, while more pronounced cell adhesion was observed on Ca-ion implanted substrates. The low energy ion implantation resulted in concurrent modifications in atomic structure, nanohardness, surface chemistry, hydrophobicity, and cell behavior on the surface of the Zr-based BMG, which were proposed to be mutually correlated with each other. - Highlights: • Low energy ion implantation of a Zr-based BMG for bone implant applications • Concurrent modifications in surface structure and properties after irradiation • Promoted adhesion of bone-forming cells after Ar- or Ca-ion implantation.

  9. Improvement of the thermoplastic formability of Zr65Cu17.5Ni10Al7.5 bulk metallic glass by minor addition of Erbium

    Science.gov (United States)

    Hu, Q.; Zeng, X. R.; Fu, M. W.; Chen, S. S.; Jiang, J.

    2016-12-01

    The softness of Zr65Cu17.5Ni10Al7.5 bulk metallic glass (BMG) in the super-cooled liquid range (SCLR) is obviously improved by minor addition of 2% Er, which makes (Zr65Cu17.5Ni10Al7.5)98Er2 (Zr65Er2) to be a very formable Be-free Zr-based BMG. It is found the lower glass transition temperature of Zr65Er2 has an important contribution to the improvement of formability, which is contrary to the general understanding that the larger fragility and wider super-cooled liquid region (SCLR) are the major reasons for better thermoplastic formability. This finding is well explained by using the linear simplification of the SCLR in Angell plot. Zr65Er2 also has lower crystallization temperature and melting temperature, which is believed to be related to the formation of short-range ordering with lower transition energy rather than the composition shift to near eutectic. The above results help understand the effect of minor addition of rare-earth to the formability of Zr-based bulk metallic glasses.

  10. Influence of the irradiation temperature on the surface structure and physical/chemical properties of Ar ion-irradiated bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Menéndez, E., E-mail: Enric.MenendezDalmau@fys.kuleuven.be [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Hynowska, A.; Fornell, J.; Suriñach, S. [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Montserrat, J. [Institut de Microelectrònica de Barcelona (IMB-CNM), CSIC, Campus Universitat Autònoma Barcelona, E-08193 Bellaterra (Spain); Temst, K.; Vantomme, A. [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Baró, M.D. [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); García-Lecina, E. [Surfaces Division, IK4-CIDETEC, Parque Tecnológico de San Sebastián, E-20009 Donostia (Spain); Pellicer, E., E-mail: Eva.Pellicer@uab.cat [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Sort, J., E-mail: Jordi.Sort@uab.cat [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain)

    2014-10-15

    Highlights: • Ion irradiation is performed on bulk metallic glasses at 300 K and close to T{sub g}. • Nanocrystallization is observed after high-temperature irradiation. • The mechanical properties are enhanced after the irradiation procedures. • Corrosion resistance is improved after irradiation close to T{sub g}. - Abstract: Surface treatments using multiple Ar ion irradiation processes with a maximum energy and fluence of 200 keV and 1 × 10{sup 16} ions/cm{sup 2}, respectively, have been performed on two different metallic glasses: Zr{sub 55}Cu{sub 28}Al{sub 10}Ni{sub 7} and Ti{sub 40}Zr{sub 10}Cu{sub 38}Pd{sub 12}. Analogous irradiation procedures have been carried out at room temperature (RT) and at T = 620 K (≈0.9 T{sub g}, where T{sub g} denotes the glass transition). The structure, mechanical behavior, wettability and corrosion resistance of the irradiated alloys have been compared with the properties of the as-cast and annealed (T = 620 K) non-irradiated specimens. While ion irradiation at RT does not significantly alter the amorphous structure of the alloys, ion irradiation close to T{sub g} promotes decomposition/nanocrystallization. Consequently, the hardness (H) and reduced Young’s modulus (E{sub r}) decrease after irradiation at RT but they both increase after irradiation at 620 K. While annealing close to T{sub g} increases the hydrophobicity of the samples, irradiation induces virtually no changes in the contact angle when comparing with the as-cast state. Concerning the corrosion resistance, although not much effect is found after irradiation at RT, an improvement is observed after irradiation at 620 K, particularly for the Ti-based alloy. These results are of practical interest in order to engineer appropriate surface treatments based on ion irradiation, aimed at specific functional applications of bulk metallic glasses.

  11. Room-temperature dynamic quasi-elastic mechanical behavior of a Zr-Cu-Fe-Al bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zadorozhnyy, V.Yu.; Zadorozhnyy, M.Yu.; Shuryumov, A.Yu.; Golovin, I.S. [National University of Science and Technology ' ' MISiS' ' , 119049, Moscow (Russian Federation); Ketov, S.V.; Louzguine-Luzgin, D.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577 (Japan)

    2016-02-15

    The paper represents storage modulus and internal friction modulation upon cyclic loading of Zr{sub 61}Cu{sub 27}Fe{sub 2}Al{sub 10} bulk metallic glassy samples within quasi-reversible deformation regime. The structure of the samples was studied by X-ray diffraction and transmission electron microscopy including high-resolution imaging and selected-area electron diffraction. It is found that kinetically frozen anelastic deformation accumulates on mechanical cycling at room temperature and causes an increase in the storage modulus and even nanocrystallization of a metallic glassy phase after a certain number of cycles. The study has shown that even a minor cyclic deformation in an elastic region can lead to the changes the atomic structure and in turn affect the elastic modulus. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Crystallization in Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass under pressure

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Zhou, T.J.; Rasmussen, Helge Kildahl;

    2000-01-01

    The effect of pressure on the crystallization behavior of the bulk metallic glass-forming Zr41.2Ti13.8Cu12.5Ni10Be22.5 alloy with a wide supercooled liquid region has been investigated by in situ high-pressure and high-temperature x-ray powder diffraction measurements using synchrotron radiation....... In the pressure range from 0 to 3 GPa, the crystallization temperature increases with pressure having a slope of 19 K/GPa, which can be explained by the suppression of atomic mobility. This observation is opposite to the results of W.H. Wang, D.W. He, D.Q. Zhao, and Y.S. Yao [Appl. Phys. Lett. 75, 2770 (1999......)], reporting a decrease of the crystallization temperature under pressure in a pressure range of 0-6 GPa for the bulk glass Zr41Ti14Cu12.5Ni9Be22.5C1 alloy. Compressibility with a volume reduction of approximately 22% at room temperature does not induce crystallization in the Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk...

  13. Effect of vanadium substitution for zirconium on the glass forming ability and mechanical properties of a Zr{sub 65}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Khademian, Nima, E-mail: nkhademian@gmail.com [Department of Mechanics, Islamshahr Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of); Gholamipour, Reza [Iranian Research Organization for Science and Technology (IROST), Tehran (Iran, Islamic Republic of); Shahri, Farzad; Tamizifar, Morteza [Faculty of Engineering and High-Tech., Iran University of Industries and Mines (IUIM), Tehran (Iran, Islamic Republic of)

    2013-01-05

    Highlights: Black-Right-Pointing-Pointer The addition of V is effective for a decrease in GFA of Zr-based BMGs. Black-Right-Pointing-Pointer Mechanical properties of Zr-based BMGs are enhanced largely due to V addition. Black-Right-Pointing-Pointer Correlations among the elastic moduli, fracture strength, Vicker's hardness and glass transition for Zr-based BMGs. Black-Right-Pointing-Pointer Critical resolved shear stress ({tau}) of the Zr{sub 65-x}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5}V{sub x} alloys decreases with the increase of V content. - Abstract: Effect of vanadium on the thermal and mechanical properties of the Zr{sub 65}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5} bulk metallic glass has been studied. The vanadium substitution for zirconium in the bulk metallic glass leads to the decrease of the glass forming ability in constant cooling rate; as well as co-precipitation of Zr{sub 2}Ni and Zr{sub 2}Cu crystalline phases in amorphous matrix. The size of the crystallites are about 20-50 nm in amorphous matrix and they act as a barrier against of rapid propagation of shear bands. In fact, the nanocrystalline phases in amorphous matrix cause the increase of the strain and the quasi-static compression strength about 58% and 20%, respectively.

  14. Thermal stability and magnetic properties of Fe-Co-M-Zr-Nb-Ge-B (M ¼ Mo, Cr) bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    Min Xu; Qunjiao Wang

    2014-01-01

    Fe62Co8-xMxZr6Nb4Ge1B19 (M=Mo, Cr) bulk metallic glasses were synthesized in the diameter range up to 2 mm by copper mold casting, which exhibit high thermal stability and large glass-forming ability. The super-cooled liquid region diminishes by the dissolution of Mo. The addition of 2 at%Cr leads to the broading of the liquid region remarkably, resulting in the improvement of thermal stability. The crystallization takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such asα-Fe, Fe2Zr and ZrB2. The Fe-based alloys show soft ferromagnetic properties. The saturation magnetization (ss) decreases with increasing Mo or Cr content while the saturated magnetostriction increases with raising Mo or Cr content. There is no evident change in the ss and coercive force (Hc) with annealing temperature below the crystallization temperature, which suggests a more relaxed atomic configuration the glasses have. The crystallization causes a substantial enhancement in both ss and Hc. Each soft magnetic property of the glasses containing Cr with higher thermal stability is superior to that of the alloys containing Mo.

  15. Thermal stability and magnetic properties of Fe–Co–M–Zr–Nb–Ge–B (M=Mo, Cr bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    Min Xu

    2014-04-01

    Full Text Available Fe62Co8−xMxZr6Nb4Ge1B19 (M=Mo, Cr bulk metallic glasses were synthesized in the diameter range up to 2 mm by copper mold casting, which exhibit high thermal stability and large glass-forming ability. The super-cooled liquid region diminishes by the dissolution of Mo. The addition of 2 at% Cr leads to the broading of the liquid region remarkably, resulting in the improvement of thermal stability. The crystallization takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The Fe-based alloys show soft ferromagnetic properties. The saturation magnetization (σs decreases with increasing Mo or Cr content while the saturated magnetostriction increases with raising Mo or Cr content. There is no evident change in the σs and coercive force (Hc with annealing temperature below the crystallization temperature, which suggests a more relaxed atomic configuration the glasses have. The crystallization causes a substantial enhancement in both σs and Hc. Each soft magnetic property of the glasses containing Cr with higher thermal stability is superior to that of the alloys containing Mo.

  16. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  17. Enhanced plasticity of Zr-based bulk metallic glass composite by in situ formed β-Zr dendritics

    Institute of Scientific and Technical Information of China (English)

    SUN Guoyuan; CHEN Guang; CHEN Guoliang

    2007-01-01

    A Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.5 bulk metallic glasscomposite with enhanced plasticity by in situ formed bcc β-Zr solid solution was prepared by water quenching.The ductile βphase with a volume fraction of about 30% possesses a developed dendritic morphology.The composite exhibits a pure plastic strain of 10.2% combined with a large elastic strain limit of 2% and a high ultimate strength of 1778 Mpa upon room-temperature compression.Microscopic observa- tion shows numbers of wave-like shear bands distributed on the surface of the compressive samples.

  18. Friction and wear characteristics of Fe-based bulk metallic glasses%铁基块体非晶合金的摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    王莉; 晁月盛

    2011-01-01

    The amorphous alloy rods with a diameter of 5mm of Fe41 Co7 Cr1s Mo14 C15 B6 Y2 were prepared by copper mold with sucking casting method. The characteristics of dry wear behavior for Fe-based bulk metallic glasses and GCrl5 steel were investigated using pin-tray equipment at the ambient temperature in this paper. Worn surface morphologies of the samples were observed on a scanning electron microscope. Friction and wear characteristics of the Fe-based bulk metallic were studied and compared with GCrl5 steel. Result indicated that the Fe-based bulk amorphous alloy shows well wear-resistance. With the wear distance extended, Fe-based bulk amorphous alloy shows different abrasive mechanism on the 30N load. The friction coefficient of the Fe-based bulk metallic glasses and GCrl5 steel are both between 0.5 and 0.8. The two kinds of materials have the similar wear-resistance.%采用电弧熔炼、铜模吸铸法制备直径为5mm的Fe基块体非晶合金棒,利用销-盘式摩擦磨损试验机进行干摩擦磨损实验,利用扫描电子显微镜观察摩擦磨损形貌,研究了铁基块体非晶合金的摩擦磨损行为,并与GCr15轴承钢进行了对比.结果表明,铁基非晶合金具有较好的耐磨性能,30N载荷作用下,随着摩擦磨损行程的延长,铁基非晶合金体现了不同的磨损机制.铁基非晶合金与GCr15轴承钢的摩擦系数都集中在0.5~0.8之间,二者的耐磨性能相当.

  19. Making bulk-conductive glass microchannel plates

    Science.gov (United States)

    Yi, Jay J. L.; Niu, Lihong

    2008-02-01

    The fabrication of microchannel plate (MCP) with bulk-conductive characteristics has been studied. Semiconducting clad glass and leachable core glass were used for drawing fibers and making MCP. Co-axial single fiber was drawn from a platinum double-crucible in an automatic fiberizing system, and the fibers were stacked and redrawn into multifiber by a special gripping mechanism. The multifibers were stacked again and the boule was made and sliced into discs. New MCPs were made after chemically leaching process without the traditional hydrogen firing. It was shown that bulk-conductive glass MCP can operate at higher voltage with lower noise.

  20. Roles of hydrogenation, annealing and field in the structure and magnetic entropy change of Tb-based bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    Qiang Luo

    2013-03-01

    Full Text Available The reduction of open-volume regions in Tb-based metallic glass (MG by annealing and hydrogen charging was found to rearrange the atomic structure and tune the magnetic behaviors. After crystallization, the magnetic structure and magnetic entropy change (MEC alters due to the structural transformation, and a plateau-like-MEC behavior can be obtained. The hydrogen concentration after charging at 1mA/cm2 for 576 h reaches as high as 3290 w-ppm. The magnetization behavior and the MEC change due to the modification of the exchange interaction and the random magnetic anisotropy (RMA upon hydrogenation. At low temperatures, irreversible positive MEC was obtained, which is related to the internal entropy production. The RMA-to-exchange ratio acts as a switch to control the irreversible entropy production channel and the reversible entropy transfer channel. The field dependence of the MEC is discussed in term of the competition among Zeeman energy, exchange interaction and RMA.

  1. The Effect of Ag Addition on the Enhancement of the Thermal and Mechanical Properties of CuZrAl Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Tsan-Man Chung

    2016-09-01

    Full Text Available In this study, the thermal and mechanical properties of Cu50−xZr43Al7Agx (x = 0, 3, 4, 5, 6 bulk metallic glasses (BMGs are investigated by using an X-ray diffractometer (XRD, a differential scanning calorimeter (DSC, differential thermal analysis (DTA, a Vickers hardness tester, a material test system (MTS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Cu50−xZr43Al7Agx (x = 0, 3, 4, 5, 6 BMGs were made by arc-melting and an injection casting process. The results revealed that the glass transition temperature (Tg and the crystallization temperature (Tx of CuZrAl alloy decreased with the Ag addition. Hence, the supercooled liquid region and γ of Cu45Zr43Al7Ag5 alloy increased to 76 K and 0.42, respectively. The thermal stability and glass forming ability of CuZrAlAg BMG alloys were enhanced by the microalloyed Ag content. The room temperature compressive fracture strength and strain measured of Cu47Zr43Al7Ag3 were about 2200 MPa and 2.1%, respectively. The distribution of vein patterns and the formation of nanocrystalline phases on the fracture surface of Cu47Zr43Al7Ag3 alloy can be observed by SEM and TEM to be significant, indicating a typical ductile fracture behavior and an improved plasticity of alloys with the addition of microalloyed Ag from 0 to 6 atom %.

  2. Structure Evolution of Bulk Metallic Glass Zr52.5Ni14.6Al10Cu17.9Ti5 during Annealing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Bulk metallic glass Zr52.5Ni14.6Al10Cu17.9Ti5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively, By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM), the predominant crystallized phase of Zr2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr2Ni0.67O0.33 and a small amount of ZrAl and Zr2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr2Ni0.67O0.33 is interface-controlled, but is diffusion-controlled to Zr2Cu and ZrAl, With increasing annealing temperature up to 200 K above Tx, the nanometer grains became very fine because of the increase of nucleation rate for Zr2Cu and ZrAl.

  3. Beyond packing of hard spheres: The effects of core softness, non-additivity, intermediate-range repulsion, and many-body interactions on the glass-forming ability of bulk metallic glasses

    Science.gov (United States)

    Zhang, Kai; Fan, Meng; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

    2015-11-01

    When a liquid is cooled well below its melting temperature at a rate that exceeds the critical cooling rate Rc, the crystalline state is bypassed and a metastable, amorphous glassy state forms instead. Rc (or the corresponding critical casting thickness dc) characterizes the glass-forming ability (GFA) of each material. While silica is an excellent glass-former with small Rc alloys are typically poor glass-formers with large Rc > 1010 K/s. Only in the past thirty years have bulk metallic glasses (BMGs) been identified with Rc approaching that for silica. Recent simulations have shown that simple, hard-sphere models are able to identify the atomic size ratio and number fraction regime where BMGs exist with critical cooling rates more than 13 orders of magnitude smaller than those for pure metals. However, there are a number of other features of interatomic potentials beyond hard-core interactions. How do these other features affect the glass-forming ability of BMGs? In this manuscript, we perform molecular dynamics simulations to determine how variations in the softness and non-additivity of the repulsive core and form of the interatomic pair potential at intermediate distances affect the GFA of binary alloys. These variations in the interatomic pair potential allow us to introduce geometric frustration and change the crystal phases that compete with glass formation. We also investigate the effect of tuning the strength of the many-body interactions from zero to the full embedded atom model on the GFA for pure metals. We then employ the full embedded atom model for binary BMGs and show that hard-core interactions play the dominant role in setting the GFA of alloys, while other features of the interatomic potential only change the GFA by one to two orders of magnitude. Despite their perturbative effect, understanding the detailed form of the intermetallic potential is important for designing BMGs with cm or greater casting thickness.

  4. Dynamics of Johari-Goldstein β relaxation and its universal relation to α relaxation in bulk metallic glasses by mechanical spectroscopy

    Science.gov (United States)

    Wu, Xuebang; Guo, Lijun; Liu, C. S.

    2014-06-01

    The dynamics of the Johari-Goldstein (JG) β relaxation and the α relaxation in bulk metallic glasses (MGs) has been investigated by using mechanical spectroscopy combined with the Coupling Model. The β relaxations of MGs exhibit different behaviors such as peaks, humps, and excess wings due to the different fluctuations of the chemical interactions among the constituting atoms. A universal correlation between the β relaxation and the α relaxation is generally found by their activation energies and relaxation times as well as the non-exponentiality parameter of the α relaxation, which can be predicted quantitatively from the Coupling Model. Based on the quasi-point defects theory, a correlation factor χ shows a broad peak along with the β relaxation, suggesting that the concentration and the correlation degree of the string-like configurations involved in the β relaxation vary with increasing temperature, which challenges the previous view that the system is in an iso-configuration state below Tg and may shed new light on the nature of the JG β relaxation in metallic glasses.

  5. Equation of state of Zr41 Ti14 Cu12.5 Ni10 Be22.5 bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    ZHAN Zai-ji; LIU Qiu-yun; ZHENG Run-guo; WANG Wen-kui; LIU Jing

    2007-01-01

    The knowledge of the equation of state (EOS) and the compressibilityof a solid are of central importance for the understanding of the behavior and the application of a condensed matter. The compression behavior of Zr41 Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with synchrotron radiation. A model of basic cell volume has been established and the equation of state of BMG is determined by the calculation of radial distribution function. The experimental results indicate that the BMG contains a large amount of vacancy-like free volume.Low pressure ( below 7 GPa) induces the collapse of the free volume to some extent and structure relaxation in the BMG.

  6. Effect of annealing on the magnetic properties of Nd{sub 70}Fe{sub 20}Al{sub 10} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Olivetti, Elena [Istituto Elettrotecnico Nazionale Galileo Ferraris, INFM, UdR To-Poli, Strada dele Cacce 91, I-10135 Torino (Italy); Dip. Chimica IFM, Universita di Torino, Via P. Giuria 9, I-10125, Torino (Italy); Baricco, Marcello [Dip. Chimica IFM, Universita di Torino, Via P. Giuria 9, I-10125, Torino (Italy); Ferrara, Enzo [Istituto Elettrotecnico Nazionale Galileo Ferraris, INFM, UdR To-Poli, Strada dele Cacce 91, I-10135 Torino (Italy); Tiberto, Paola [Istituto Elettrotecnico Nazionale Galileo Ferraris, INFM, UdR To-Poli, Strada dele Cacce 91, I-10135 Torino (Italy)]. E-mail: tiberto@ien.it; Martino, Luca [Istituto Elettrotecnico Nazionale Galileo Ferraris, INFM, UdR To-Poli, Strada dele Cacce 91, I-10135 Torino (Italy)

    2005-04-15

    In this work, the influence of thermal treatments on the hysteresis behaviour of Nd{sub 70}Fe{sub 20}Al{sub 10} bulk metallic glasses is studied. Two samples obtained applying different quenching rates have been characterized: (a) master alloy ingots, prepared through arc melting, and (b) cone-shaped ingots obtained by copper mould casting. DSC measurements have been performed on both alloys. Selected samples have been submitted to subsequent annealing. Hard magnetic properties have been observed at room temperature either in the as-cast master alloy or in the cone-shaped ingots. High values of coercivity are still observed after treatment at temperatures close to the crystallisation temperature (up to 500 deg. C). The different magnetic behaviour of the samples is discussed in terms of differences in the residual amorphous phase composition.

  7. Structural and Mechanical Characterization of Zr58.5Ti8.2Cu14.2Ni11.4Al7.7 Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Jürgen Eckert

    2011-12-01

    Full Text Available Thermal stability, structure and mechanical properties of the multi-component Zr58.5Ti8.2Cu14.2Ni11.4Al7.7 bulk metallic glass have been studied in detail. The glassy material displays good thermal stability against crystallization and a fairly large supercooled liquid region of 52 K. During heating, the alloy transforms into a metastable icosahedral quasicrystalline phase in the first stage of crystallization. At high temperatures, the quasicrystalline phase undergoes a transformation to form tetragonal and cubic NiZr2-type phases. Room-temperature compression tests of the as-cast sample show good mechanical properties, namely, high compressive strength of about 1,630 MPa and fracture strain of 3.3%. This is combined with a density of 6.32 g/cm3 and values of Poisson’s ratio and Young’s modulus of 0.377 and 77 GPa, respectively. The mechanical properties of the glass can be further improved by cold rolling. The compressive strength rises to 1,780 MPa and the fracture strain increases to 8.3% for the material cold-rolled to a diameter reduction of 10%.

  8. The effects of initial welding temperature and welding parameters on the crystallization behaviors of laser spot welded Zr-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huei-Sen, E-mail: huei@mail.isu.edu.tw [Department of Materials Science and Engineering, I-Shou University, Kaohsiung County 84001, Taiwan (China); Chiou, Mau-Sheng; Chen, Hou-Guang [Department of Materials Science and Engineering, I-Shou University, Kaohsiung County 84001, Taiwan (China); Jang, Jason Shian-Ching [Department of Mechanical Engineering, National Central University, Taoyuan County 32001, Taiwan (China)

    2011-09-15

    This study investigated the effects of the initial welding temperature (IWT) and welding parameters on the crystallization behaviors of laser spot welded (Zr{sub 53}Cu{sub 30}Ni{sub 9}Al{sub 8})Si{sub 0.5} bulk metallic glass (BMG). After the welding process, the microstructure evolution, glass-forming ability (GFA) and mechanical properties of the welded samples were determined by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Vicker's micro-hardness test. The results showed that the heat-affected zone (HAZ) crystallization seemed avoidable under the room temperature welding process. However, with a combination of a lower energy input (welding Condition C) and a lower IWT (at 0 deg. C), a crystallization-free HAZ was finally obtained. Using the above welding condition into the refined heat flow equation, a critical retention time of 79 ms for the crystallization temperature interval was estimated. Moreover, as the laser welded samples came to crystallization in the HAZ, it was observed that a higher content of spherical-type crystalline precipitates tended to result in a higher value of glass transition temperature, T{sub g}. Therefore, the GFA indices, {Delta}T{sub x}, {gamma} and {gamma}{sub m}, were reduced. Furthermore, it was found that the micro-hardness value in the HAZ crystallization area was decreased due to the massive cracks formed in most parts of the crystalline precipitates. For a crystallization-free HAZ, the hardness seemed unaffected.

  9. Super-plasticity of Zr64.80Cu14.85Ni10.35Al10 bulk metallic glass at room temperature

    Institute of Scientific and Technical Information of China (English)

    TAO PingJun; YANG YuanZheng; BAI XiaoJun; XIE ZhiWei; CHEN XianCao; DONG ZhenJiang; Wen JianGuo

    2008-01-01

    Generally, bulk metallic glasses (BMGs) exhibit a very limited plastic deformation under a compression load at room temperature, often less than 2% before fracturing. In this letter, through an appropriate choice of BMGs' composition, an amorphous rod of Zr64.80Cu14.85Ni10.35Al10 with a diameter of 2 mm was prepared by using copper mold suction casting. X-ray diffraction and differential scanning calorimetry were utilized to determine its structure and thermal stability, and the uniaxial compression test was adopted to study its plastic deformation behavior at room temperature simultaneously. The results showed that the glass transition temperature and onset temperature of the exothermic reaction of the amorphous rod were 646 and 750 K, respectively, and its micro-hardness was 594.7 Hv. During com-pression, when the engineering strain and engineering stress arrived at 9.05% and 1732 MPa, respec-tively, i.e., the true strain and true stress reached 9.42% and 1560 MPa, respectively, the amorphous rod started to yield. After yielding, with the increase of load, the strain increased and the glass rod ulti-mately were compressed into flake-like form. Although the maximum engineering strain was larger than 70%, i.e., the maximum true strain exceeded by 120%, the amorphous specimen was not fractured, indicating that it has super-plasticity at room temperature. Through the appropriate choice of compo-sition and optimization of the technological process, flexible BMG with super-plasticity at room tem-perature could be produced.

  10. Beyond packing of hard spheres: The effects of core softness, non-additivity, intermediate-range repulsion, and many-body interactions on the glass-forming ability of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Fan, Meng; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-11-14

    When a liquid is cooled well below its melting temperature at a rate that exceeds the critical cooling rate R{sub c}, the crystalline state is bypassed and a metastable, amorphous glassy state forms instead. R{sub c} (or the corresponding critical casting thickness d{sub c}) characterizes the glass-forming ability (GFA) of each material. While silica is an excellent glass-former with small R{sub c} < 10{sup −2} K/s, pure metals and most alloys are typically poor glass-formers with large R{sub c} > 10{sup 10} K/s. Only in the past thirty years have bulk metallic glasses (BMGs) been identified with R{sub c} approaching that for silica. Recent simulations have shown that simple, hard-sphere models are able to identify the atomic size ratio and number fraction regime where BMGs exist with critical cooling rates more than 13 orders of magnitude smaller than those for pure metals. However, there are a number of other features of interatomic potentials beyond hard-core interactions. How do these other features affect the glass-forming ability of BMGs? In this manuscript, we perform molecular dynamics simulations to determine how variations in the softness and non-additivity of the repulsive core and form of the interatomic pair potential at intermediate distances affect the GFA of binary alloys. These variations in the interatomic pair potential allow us to introduce geometric frustration and change the crystal phases that compete with glass formation. We also investigate the effect of tuning the strength of the many-body interactions from zero to the full embedded atom model on the GFA for pure metals. We then employ the full embedded atom model for binary BMGs and show that hard-core interactions play the dominant role in setting the GFA of alloys, while other features of the interatomic potential only change the GFA by one to two orders of magnitude. Despite their perturbative effect, understanding the detailed form of the intermetallic potential is important for

  11. Effect of Nb in (La0.5Ce0.5)64-xAl16Ni5Cu15Nbx (x=0-5) bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-qing; LIU Jin-fang; ZENG Qiao-shi; WANG Li-na; LIU Jin-qiang; JIANG Jian-zhong

    2006-01-01

    The effect of Nb in (La0.5Ce0.5)64-xAl16Ni5Cu15Nbx (x=0-5, mole fraction) bulk metallic glasses was investigated by X-ray diffractometry, differential scanning calorimetry, and scanning electron microscopy. Fully amorphous rods up to 5 mm in diameter were obtained using copper mold. Their lower glass transition temperatures are of about 401-407 K and wide supercooled liquid regions are up to 75 K. The oxidation resistance of the LaCe-based glassy alloys can be largely enhanced by adding tiny Nb, which makes the developed LaCe-based bulk metallic glasses more attractive for potential industrial applications.

  12. Heavy Metal Fluoride Glasses.

    Science.gov (United States)

    1987-04-01

    i 2N E ihhhhh1112h MEmhhhhEEEohhhhE I.’....momo 111111111’-20 LA ’Ll2. AFWL-TR-86-37 AFWL-TR- 86-37 oT C ,l C ’-’ N HEAVY METAL FLUORIDE GLASSES 0nI...Secwrit CkasmfcationJ HEAVY METAL FLUORIDE GLASSES 12. PERSONAL AUTHOR(S) Reisfield, Renata; and Eyal, Mrek 13. TYPE OF REPORT 113b. TIME COVERED 114...glasses containing about 50 mole% of ZrF4 [which can be replaced by HfF 4 or TIF 4 (Refs. 1-3) or heavy metal fluorides based on PbF2 and on 3d-group

  13. Strong work-hardening behavior induced by the solid solution strengthening of dendrites in TiZr-based bulk metallic glass matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ma, D.Q. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Jiao, W.T. [College of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004 (China); Zhang, Y.F. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Wang, B.A.; Li, J.; Zhang, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2015-03-05

    Highlights: • Hardness of dendrite of TiZr-based BMGMCs increases. • Strong work-hardening behavior is obtained after solid solution strengthening. • Lattice distortions of dendrite suffering from rapid cooling are detected. - Abstract: A series of TiZr-based bulk metallic glass matrix composites (BMGMCs) with distinguished mechanical properties are successfully fabricated by adding different volume fractions of Ta (Ti{sub 38.8}Zr{sub 28.8}Cu{sub 6.2}Be{sub 16.2}Nb{sub 10} as the basic composition, denoted as Ta{sub 0.0}–Ta{sub 8.0}). Along with the growth of precipitated phase, typical dendritic morphology is fully developed in the TiZr-based BMGMCs of Ta{sub 8.0}. Energy-dispersive spectrometry analysis of the dendrites and glass matrix indicates that the metallic elements of Nb and Ta should preferentially form solid solution into dendrites. The chaotic structure of high-temperature precipitate phase is trapped down by the rapid cooling of the copper-mould. The detected lattice distortions in the dendrites are attributed to the strong solid solution strengthening of the metallic elements of Ti, Zr, Nb, and Ta. These lattice distortions increase the resistance of the dislocation motion and pin the dislocations, thus the strength and hardness of dendrite increase. Dendrites create a strong barrier for the shear band propagation and generate multiple shear bands after solid solution strengthening, thereby providing the TiZr-based BMGMCs with greatly improved capacity to sustain plastic deformation and resistance to brittle fracture. Thus, the TiZr-based BMGMCs possess distinguished work-hardening capability. Among these TiZr-based BMGMCs, the sample Ta{sub 0.5} possesses the largest plastic strain (ε{sub p}) at 20.3% and ultimate strength (σ{sub max}) of 2613 MPa during compressive loading. In addition, the sample of Ta{sub 0.5} exhibits work-hardening up to an ultrahigh tensile strength of 1680 MPa during the tensile process, and then progressively

  14. The Effect of Thermal Cycling Treatments on the Thermal Stability and Mechanical Properties of a Ti-Based Bulk Metallic Glass Composite

    Directory of Open Access Journals (Sweden)

    Fan Bu

    2016-11-01

    Full Text Available The effect of thermal cycling treatments on the thermal stability and mechanical properties of a Ti48Zr20Nb12Cu5Be15 bulk metallic glass composite (BMGC has been investigated. Results show that moderate thermal cycles in a temperature range of −196 °C (cryogenic temperature, CT to 25 °C (room temperature, RT or annealing time at CT has not induced obvious changes of thermal stability and then it decreases slightly over critical thermal parameters. In addition, the dendritic second phases with a bcc structure are homogeneously embedded in the amorphous matrix; no visible changes are detected, which shows structural stability. Excellent mechanical properties as high as 1599 MPa yield strength and 34% plastic strain are obtained, and the yield strength and elastic modulus also increase gradually. The effect on the stability is analyzed quantitatively by crystallization kinetics and plastic-flow models, and indicates that the reduction of structural relaxation enthalpy, which is related to the degradation of spatial heterogeneity, reduces thermal stability but does not imperatively deteriorate the plasticity.

  15. Structural and magnetic properties of the Gd-based bulk metallic glasses GdFe2, GdCo2, and GdNi2 from first principles

    Science.gov (United States)

    Lizárraga, Raquel

    2016-11-01

    A structural and magnetic characterization of Gd-based bulk metallic glasses, GdFe2, GdCo2, and GdNi2, was performed. Models for the amorphous structures for two magnetic configurations, ferromagnetic and ferrimagnetic, were obtained by means of a first-principles-based method, the stochastic quenching. In all three cases, the ferrimagnetic configuration was energetically more stable than the ferromagnetic one, in perfect agreement with experiments. In the structural analysis, radial and angle distribution functions as well as calculations of bond lengths and average coordination numbers were included. Structural properties are in good agreement with experiments and do not depend on the magnetic configuration. The distribution of magnetic moments shows that amorphous GdFe2 and GdCo2 are both ferrimagnets, with antiparallel alignment of the magnetic moments of the two magnetic sublattices, whereas Ni nearly loses its magnetic moment in amorphous GdNi2, similar to the situation in its crystalline counterpart.

  16. Large size metallic glass gratings by embossing

    Science.gov (United States)

    Ma, J.; Yi, J.; Zhao, D. Q.; Pan, M. X.; Wang, W. H.

    2012-09-01

    Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (˜8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light.

  17. Fe60CoxZr10Mo5W2B23-x(x=1,3,5,7,9)块状金属玻璃的非晶形成能力%Glass forming ability of Fe60 Cox Zr10Mo5 W2B23-x (x = 1,3,5,7,9) bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    刘冬艳; 张海峰; 邓胜涛; 胡壮麒

    2005-01-01

    The bulk Fe60CoxZr10Mo5W2B23-x (x= 1, 3, 5, 7, 9) amorphous rods with diameters of1.5 mm were successfully prepared by copper mold casting method with the low purity raw materials.The amorphous and crystalline states, and thermal parameters, such as the glass transition temperature (Tg), the initial crystallization temperature (Tx), the supercooled liquid region (ΔTx = TxTg), the reduced glass transition temperature Trg (Tg/Tm, Tm: the onset temperature of melting of the alloy, and Tg/T1, T1 : the finished temperature of melting of the alloy) were investigated by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) analysis. Glass forming ability of Fe60CoxZr10Mo5W2B23-x (x=1, 3, 5, 7, 9)bulk metallic glasses has been studied. According to the results, the alloy (x=7) with the highest Trg (Tg/T1 =0. 607, Tg/T1 =0.590) value, has the strongest glass forming ability among these alloys because its composition is near eutectic composition.The wide supercooled liquid region over 72 K indicates the high thermal stability for this alloy system.This bulk metallic glass exhibits quite high strength (Hv 1020). The success of production of the Febased bulk metallic glass with industrial materials is of great significance for the future progress of basic research and practical application.

  18. Influence of thermal treatments and plastic deformation on the atomic mobility in Zr{sub 50.7}Cu{sub 28}Ni{sub 9}Al{sub 12.3} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, J.C.; Pelletier, J.M., E-mail: jean-marc.pelletier@insa-lyon.fr

    2014-12-05

    Highlights: • Atomic mobility in Zr-based metallic glass were evaluated by DMA and nanoindentation. • Atomic mobility is reduced by physical aging while increased by plastic deformation. • The atomic mobility in metallic glasses are related to concentration of “defects”. • Value of the Kohlrausch exponent β{sub KWW} in the Zr-based metallic glass is around 0.5. - Abstract: The atomic mobility in Zr{sub 50.7}Cu{sub 28}Ni{sub 9}Al{sub 12.3} bulk metallic glass has been evaluated as a function of temperature and the influence of different treatments (thermal annealing, plastic deformation) has been investigated using mechanical spectroscopy and nanoindentation technique. In particular the loss factor has been measured. This parameter is connected to the energy loss during the application of a periodic stress and therefore is sensitive to atomic movements. Master curves can be obtained, confirming the validity of the time–temperature superposition principle. The atomic mobility is reduced during physical aging (also called structural relaxation) but increased after a plastic deformation (a rejuvenation of the material is then induced). In the framework of the nanoindentation tests and mechanical spectroscopy, the concentration of “defects” in metallic glasses increases by deformation (i.e. cold-rolling) while decreases after structural relaxation and crystallization. These results are discussed using the concept of quasi-point defects, which assist the atomic movements.

  19. Glass formation and mechanical properties of (Cu{sub 50}Zr{sub 50}){sub 100-x}Al{sub x} (x = 0, 4, 5, 7) bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Baser, T.A. [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, University of Torino, Via P. Giuria 9, 10125 Torino (Italy); Das, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); TU Dresden, Institut fuer Werkstoffwissenschaft, D-01062 Dresden (Germany); Baricco, M., E-mail: marcello.baricco@unito.i [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, University of Torino, Via P. Giuria 9, 10125 Torino (Italy)

    2009-08-26

    The effect of Al content on the glass formation and mechanical properties was studied for (Cu{sub 50}Zr{sub 50}){sub 100-x}Al{sub x} (x = 0, 4, 5, 7) bulk metallic glasses. The crystallization temperatures of fully amorphous Cu{sub 50}Zr{sub 50}, Cu{sub 48}Zr{sub 48}Al{sub 4}, Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} and Cu{sub 46.5}Zr{sub 46.5}Al{sub 7} as-cast rods are 724 K, 753 K, 758 K and 782 K, respectively. The mechanical properties were investigated under compression at room temperature. As-cast Cu{sub 46.5}Zr{sub 46.5}Al{sub 7} shows the highest yield strength (1867 MPa), whereas Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} shows the largest fracture strain of 11.2%. The fracture surfaces of the compressed samples were investigated by scanning electron microscopy and their morphology has been correlated with the compressive plasticity.

  20. On the low-temperature absorption of longitudinal ultrasound in Zr52.5Ti5Cu17.9Ni14.6Al10 bulk metallic glass

    Science.gov (United States)

    Bakai, S. A.; Bulatov, A. S.; Klochko, V. S.; Korniets, A. V.; Fateev, M. P.

    2012-10-01

    Ultrasonic absorption and attenuation in Zr52.5Ti5Cu17.9Ni14.6Al10 bulk metallic glass have been investigated at frequencies of 20, 50 and 150 MHz and temperatures from 80 to 300 K. Using the obtained data the activation energy spectrum of defects responsible for the ultrasonic attenuation is estimated. The results are discussed in the framework of the Debye relaxation model.

  1. Al基块体金属玻璃的研究进展%Research Progress in Al-based Bulk Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    陈思泉; 李艳辉; 张伟

    2016-01-01

    Al-based metallic glasses (MGs)exhibit high strength,high toughness,and good corrosion resis-tance.Especially,Al-based MGs possess high special strength which is up to 330 kN·m/kg.Therefore,Al-based MGs are promising for applications as a new type of structural materials in aerospace fields.In recent years,Al-based MGs with high glass-forming ability (GFA)and high supercooled liquid stability have been developed,and the MG samples in bulk form have been produced via copper mold casting and consolidation of Al-based MG powders as well, which will promote their practical use.In this paper,the research progress in the development,GFA,stabilization of supercooled liquid,and mechanical properties of Al-based MGs,together with the structure and properties of sintered Al-based MGs powder are reviewed.The problems during the development of the alloys are discussed.%Al基金属玻璃具有高强度、高韧性、良好的耐蚀性,特别是其比强度高达330 kN·m/kg,作为新结构材料在航空航天领域具有潜在的应用前景。近年不仅研发出了具有大过冷液相区以及能形成块体金属玻璃的Al基合金,还通过粉体温热固化成形工艺实现了Al基金属玻璃的大块体化,推动了其在实际生产中的应用。简述了有关Al基金属玻璃合金的玻璃形成能力、过冷液体热稳定性、力学性能及其粉末烧结体的组织和性能等方面的最新研究进展,并对其发展存在的问题进行了探讨。

  2. Drastic influence of minor Fe or Co additions on the glass forming ability, martensitic transformations and mechanical properties of shape memory Zr-Cu-Al bulk metallic glass composites

    Science.gov (United States)

    González, Sergio; Pérez, Pablo; Rossinyol, Emma; Suriñach, Santiago; Baró, Maria Dolors; Pellicer, Eva; Sort, Jordi

    2014-06-01

    The microstructure and mechanical properties of Zr48Cu48 - x Al4M x (M ≡ Fe or Co, x = 0, 0.5, 1 at.%) metallic glass (MG) composites are highly dependent on the amount of Fe or Co added as microalloying elements in the parent Zr48Cu48Al4 material. Addition of Fe and Co promotes the transformation from austenite to martensite during the course of nanoindentation or compression experiments, resulting in an enhancement of plasticity. However, the presence of Fe or Co also reduces the glass forming ability, ultimately causing a worsening of the mechanical properties. Owing to the interplay between these two effects, the compressive plasticity for alloys with x = 0.5 (5.5% in Zr48Cu47.5Al4Co0.5 and 6.2% in Zr48Cu47.5Al4Fe0.5) is considerably larger than for Zr48Cu48Al4 or the alloys with x = 1. Slight variations in the Young’s modulus (around 5-10%) and significant changes in the yield stress (up to 25%) are also observed depending on the composition. The different microstructural factors that have an influence on the mechanical behavior of these composites are investigated in detail: (i) co-existence of amorphous and crystalline phases in the as-cast state, (ii) nature of the crystalline phases (austenite versus martensite content), and (iii) propensity for the austenite to undergo a mechanically-driven martensitic transformation during plastic deformation. Evidence for intragranular nanotwins likely generated in the course of the austenite-martensite transformation is provided by transmission electron microscopy. Our results reveal that fine-tuning of the composition of the Zr-Cu-Al-(Fe,Co) system is crucial in order to optimize the mechanical performance of these bulk MG composites, to make them suitable materials for structural applications.

  3. Kinetic analysis of the non-isothermal crystallization process, magnetic and mechanical properties of FeCoBSiNb and FeCoBSiNbCu bulk metallic glasses

    Science.gov (United States)

    Ramasamy, Parthiban; Stoica, Mihai; Taghvaei, A. H.; Prashanth, K. G.; Ravi Kumar, Eckert, Jürgen

    2016-02-01

    The crystallization kinetics of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 and {[(Fe0.5Co0.5)0.75B0.2Si0.05]0.96Nb0.04}99.5Cu0.5 bulk metallic glasses were evaluated using differential scanning calorimetry under non-isothermal condition. The fully glassy rods with diameters up to 2 mm were obtained by copper mold injection casting. Both glasses show good thermal stability, but the addition of only 0.5% Cu completely changes the crystallization behavior. The average activation energy required for crystallization decreases from 645 kJ/mol to 425 kJ/mol after Cu addition. Upon heating, the Cu-free alloy forms only the metastable Fe23B6 phase. In contrast, two well-separated exothermic events are observed for the Cu-added bulk glassy samples. First, the (Fe,Co) phase nucleates and then (Fe,Co)2B and/or (Fe,Co)3B crystallize from the remaining glassy matrix. The Cu-added alloy exhibits a lower coercivity and a higher magnetic saturation than the base alloy, both in as-cast as well as in annealed condition. Besides, the Cu-added glassy sample with 2 mm diameter exhibits a maximum compressive fracture strength of 3913 MPa together with a plastic strain of 0.6%, which is highest plastic strain ever reported for 2 mm diameter ferromagnetic bulk metallic glass sample. Although Cu addition improves the magnetic and mechanical properties of the glass, it affects the glass-forming ability of the base alloy.

  4. Preparation of Carbon-nanotube Reinforced Mg Based Bulk Metallic Glass Composites and Its Mechanical Properties%碳纳米管—镁基非晶复合材料的制备及力学性能

    Institute of Scientific and Technical Information of China (English)

    赵平; 李双寿; 彭浩; 刘金海

    2011-01-01

    Carbon-nanotube reinforced Mg-based bulk metallic glass composites were prepared successfully with copper mold by differential pressure casting. Moreover, the microstructure, compressive behavior, fracture strength as well as fracture morphology of the composites were investigated. The results show that there exists desirable bonding between carbon-nanotube particle and the Mg-based bulk metallic glass, and the glass forming ability and thermal stability of the Mg-based bulk metallic glass can not be apparently changed by the induction of carbon-nanotube particle. Compared with the matrix a-morphous alloy, the composites exhibit obvious advantages in the maximum compressive strength and fracture displacement. Carbon-nanotube is uniformly distributed into the matrix amorphous alloy in the absence of large-area colony, meanwhile, amounts of dimple structure in the fracture morphology of the composites can be observed.%采用铜模差压压铸的方法成功制备了碳纳米管颗粒增强镁基非晶复合材料,并对其微观结构、压缩性能、断裂强度及断口形貌进行了研究.结果表明,碳纳米管颗粒与非晶基体结合良好,其引入没有明显改变基体非晶合金的玻璃形成能力和热稳定性能;与非晶合金相比,复合材料的最大压缩强度及断裂位移有明显提高.碳纳米管在基体中复合的比较均匀,没有出现大面积团聚,并形成很多韧窝结构.

  5. High-Entropy Metallic Glasses

    Science.gov (United States)

    Wang, W. H.

    2014-10-01

    The high-entropy alloys are defined as solid-solution alloys containing five or more than five principal elements in equal or near-equal atomic percent. The concept of high mixing entropy introduces a new way for developing advanced metallic materials with unique physical and mechanical properties that cannot be achieved by the conventional microalloying approach based on only a single base element. The metallic glass (MG) is the metallic alloy rapidly quenched from the liquid state, and at room temperature it still shows an amorphous liquid-like structure. Bulk MGs represent a particular class of amorphous alloys usually with three or more than three components but based on a single principal element such as Zr, Cu, Ce, and Fe. These materials are very attractive for applications because of their excellent mechanical properties such as ultrahigh (near theoretical) strength, wear resistance, and hardness, and physical properties such as soft magnetic properties. In this article, we review the formation and properties of a series of high-mixing-entropy bulk MGs based on multiple major elements. It is found that the strategy and route for development of the high-entropy alloys can be applied to the development of the MGs with excellent glass-forming ability. The high-mixing-entropy bulk MGs are then loosely defined as metallic glassy alloys containing five or more than five elements in equal or near-equal atomic percent, which have relatively high mixing entropy compared with the conventional MGs based on a single principal element. The formation mechanism, especially the role of the mixing entropy in the formation of the high-entropy MGs, is discussed. The unique physical, mechanical, chemical, and biomedical properties of the high-entropy MGs in comparison with the conventional metallic alloys are introduced. We show that the high-mixing-entropy MGs, along the formation idea and strategy of the high-entropy alloys and based on multiple major elements, might provide

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

    Directory of Open Access Journals (Sweden)

    Peng Jia

    2016-11-01

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

  7. Fundamental mechanical and microstructural observations in metallic glass coating production

    NARCIS (Netherlands)

    Matthews, D.T.A.; Ocelik, V.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    The production of a wide range of metallic Glass Forming Alloys (GFA) has been investigated by several processing routes including simple arc-casting and melt-spinning to form Bulk Metallic Glasses (BMG). The concepts surrounding such alloys have been directed towards the production of thick (> 300

  8. Corrosion of Metal Inclusions In Bulk Vitrification Waste Packages

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, Diana H.; Pierce, Eric M.; Wellman, Dawn M.; Strachan, Denis M.; Josephson, Gary B.

    2006-07-31

    The primary purpose of the work reported here is to analyze the potential effect of the release of technetium (Tc) from metal inclusions in bulk vitrification waste packages once they are placed in the Integrated Disposal Facility (IDF). As part of the strategy for immobilizing waste from the underground tanks at Hanford, selected wastes will be immobilized using bulk vitrification. During analyses of the glass produced in engineering-scale tests, metal inclusions were found in the glass product. This report contains the results from experiments designed to quantify the corrosion rates of metal inclusions found in the glass product from AMEC Test ES-32B and simulations designed to compare the rate of Tc release from the metal inclusions to the release of Tc from glass produced with the bulk vitrification process. In the simulations, the Tc in the metal inclusions was assumed to be released congruently during metal corrosion as soluble TcO4-. The experimental results and modeling calculations show that the metal corrosion rate will, under all conceivable conditions at the IDF, be dominated by the presence of the passivating layer and corrosion products on the metal particles. As a result, the release of Tc from the metal particles at the surfaces of fractures in the glass releases at a rate similar to the Tc present as a soluble salt. The release of the remaining Tc in the metal is controlled by the dissolution of the glass matrix. To summarize, the release of 99Tc from the BV glass within precipitated Fe is directly proportional to the diameter of the Fe particles and to the amount of precipitated Fe. However, the main contribution to the Tc release from the iron particles is over the same time period as the release of the soluble Tc salt. For the base case used in this study (0.48 mass% of 0.5 mm diameter metal particles homogeneously distributed in the BV glass), the release of 99Tc from the metal is approximately the same as the release from 0.3 mass% soluble Tc

  9. Atomic structure of Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} bulk metallic glass alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hui, X. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: huixd01@hotmail.com; Fang, H.Z.; Chen, G.L. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Shang, S.L.; Wang, Y. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Qin, J.Y. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University - Southern Campus, Jinan 250061 (China); Liu, Z.K. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2009-01-15

    Ab initio molecular dynamics (AIMD) calculations were performed on the atomic configuration of Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} bulk metallic glass. The local structures were characterized in terms of structure factors (SF), pair correlation functions (PCF), coordinate numbers, bond pairs and Voronoi polyhedra. The glass transition temperature, generalized PCF and SF predicated by AIMD are in good agreement with the experimental data. Icosahedral short-range orders (ISRO) are found to be the most dominant, in view of the presence of the majority of bond pairs with 1551, 1541 and 1431, and Voronoi polyhedra with <0,3,6,1>, <0,2,8,1>, <0,0,12,0> and <0,2,8,4>. Icosahedral medium range orders (IMROs) are formed from icosahedra via the linkage of vertex-, edge-, face- and intercross-shared atoms. The glass structure on the nanometer scale is accumulated by polyhedra through an efficient packing mode. It is suggested that the extraordinary glass-forming ability of this alloy is essentially attributable to the formation of ISRO and IMRO, and the dense packing of atoms.

  10. Glass-forming ability analysis of selected Fe-based bulk amorphous alloys

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-09-01

    Full Text Available Purpose: The paper mainly aims to present the structure and thermal stability of selected Fe-based bulk metallic glasses: Fe72B20Si4Nb4 and Fe43Co14Ni14B20Si5Nb4.Design/methodology/approach: The investigated samples were cast in form of the rods by the pressure die casting method. The structure analysis of the studied materials in as-cast state was carried out using XRD and TEM methods. The thermal stability associated with glass transition temperature (Tg, onset (Tx and peak (Tp crystallization temperature was examined by differential scanning calorimetry (DSC. Several parameters have been used to determine the glass-forming ability of studied alloys. The parameters of GFA included reduced glass transition temperature (Trg, supercooled liquid region (ΔTx, the stability (S and (Kgl parameter.Findings: The XRD and TEM investigations revealed that the studied as-cast metallic glasses were fully amorphous. Changes of the onset and peak crystallization temperature and the glass transition temperature as a function of glassy samples thickness were stated. The good glass-forming ability (GFA enabled casting of the Fe72B20Si4Nb4 and Fe43Co14Ni14B20Si5Nb4 glassy rods.Practical implications: The obtained examination results confirm the utility of applied investigation methods in the thermal stability analysis of examined bulk amorphous alloys. It is evident that parameters Trg, ΔTx, Kgl, S could be used to determine glass-forming ability of studied bulk metallic glasses.Originality/value: The success of fabrication of studied Fe-based bulk metallic glasses in form of rods with diameter up to 3 mm is important for the future progress in research of this group of materials.

  11. Review on compressive deformation of bulk metallic glasses%块体非晶合金压缩变形研究进展

    Institute of Scientific and Technical Information of China (English)

    李明; 刘新才; 潘晶; 鲁贻虎

    2014-01-01

    In this paper,the compressive deformation behavior,samples surfaces and fracture microstructure characteristics have been reviewed at different temperatures and strain rates for bulk metallic glasses (BMGs). BMGs behave like inhomogeneous brittle fracture,non-Newtonian fluid and Newtonian fluid mode respectively at reduced compressing temperature tr=T/Tg ranging of 77 K/Tg≤tr

  12. Metal Halide Optical Glasses.

    Science.gov (United States)

    1988-01-01

    while some of the multi- component "modified" glasses (e.g., ZBLAN ) could easily be cast into pieces several mm thick. 23 The difference between the...energy. 7-1 0 Typical plots pf 24 of log Iqi versus ]/Tf for ZB-I, ZBL, ZBLA, ZBLAN and ZBLALi glasses are presented in Fig. 3. These plots are linear... ZBLAN glasses are more resistant to devitrification than the corresponding ZBLLi or ZBLN glasses , although this does not appear to be manifested in

  13. Dynamic mechanical behavior and high pressure phase stability of a zirconium-based bulk metallic glass and its composite with tungsten

    Science.gov (United States)

    Martin, Morgana

    2008-10-01

    failure stress over the range of strain rates evaluated, and work-hardening decreased as strain-rate increased. Its deformation mode was found to transition from heterogeneous deformation below the glass transition temperature (of the BMG), to homogeneous deformation between the glass transition and crystallization temperatures, and then back to heterogeneous deformation behavior above the crystallization temperature. The composite exhibited a large susceptibility to shear failure, as evidenced by much decreased strain-to-failure in biaxial (compression-shear) specimens as compared to that in uniaxial (compression) specimens. Failure took place primarily in the glass matrix and at the tungsten particle interfaces at all strain rates. Overall, the deformation and failure behavior of the composite is dominated by that of tungsten, but characteristics of BMG deformation and failure are evident, especially between the glass transition and crystallization temperatures, and at extremely high strain rates. For the monolithic BMG, fracture surfaces became increasingly more disorganized as strain rate increased, with evidence of melting due to temperature rise during fracture. The deformation and elastic-plastic wave propagation and interaction response based on measured free surface velocity traces of the monolithic glass were quite well described by the pressure-hardening Drucker-Prager model. Likewise, the deformation response of the composite was described reasonably well considering a rule of mixtures combination of properties of the BMG and W. High-pressure equation of state experiments provided evidence of transition to a mixed phase region (at ˜26 GPa) and then to a high-pressure phase (at ˜67 GPa) with a bulk modulus of 288 GPa, 144% higher than that of the bulk modulus of the ambient pressure. Specimens obtained from recovery experiments did not reveal any crystallization, indicating that any crystallites that may have formed were too small and too few to detect

  14. Using thermoforming capacity of metallic glasses to produce multimaterials

    Energy Technology Data Exchange (ETDEWEB)

    Ragani, J., E-mail: jennifer.ragani@simap.grenoble-inp.f [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France); Volland, A., E-mail: antoine.volland@simap.grenoble-inp.f [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France); Valque, S.; Liu, Y. [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France); Gravier, S., E-mail: sebastien.gravier@simap.grenoble-inp.f [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France); Blandin, J.J., E-mail: jean-jacques.blandin@simap.grenoble-inp.f [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France); Suery, M., E-mail: michel.suery@simap.grenoble-inp.f [Grenoble University/CNRS, Grenoble-INP/UJF, SIMAP Laboratory, 38402 Saint-Martin d' Heres (France)

    2010-08-15

    In addition to casting, thermoforming is a particularly interesting way to produce components in bulk metallic glasses since large strains can be achieved when the BMGs are deformed in their supercooled liquid region. The experimental window (temperature, time) in which high temperature forming can be carried out is directly related to the crystallization resistance of the glass. Such forming windows have been identified for zirconium based bulk metallic glasses thanks to thermal analysis and compression tests in the supercooled liquid region. Based on this identification, the thermoforming capacity of the studied glasses was used to produce multimaterials associating metallic glasses with conventional metallic alloys. Two processes have been preferentially investigated (co-extrusion and co-pressing) and the interface quality of the elaborated multi materials was studied.

  15. Zr52.5Al10Ni10Cu15Be12.5大块金属玻璃的高温宏观硬度%Hot macro-hardness of Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    李钧; 田瑞; 肖学山

    2007-01-01

    The hot hardness behavior of Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glass is studied from ambient temperature to the temperature over Tx (the onset crystallization temperature) using a hot macro-hardness tester and scanning electron microscopy (SEM). The results show that the hot hardness behavior of Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glass can be classified into 4 zones: the glassy zone in which the hardness almost linearly decreases with the increase of temperature, the viscoelastic zone in which the hardness is nearly unchanged, the viscous flow zone in which the hardness quickly tends towards near zero with temperature, and the crystallization zone in which the hardness sharply increases. The high temperature deformation behavior and the easy processable deformation region for bulk metallic glasses are also discussed on the basis of the hot marco-hardness.

  16. Experimental study on dynamic response of bulk metallic glass under high velocity impact%高速冲击下块体金属玻璃动力学响应的实验研究

    Institute of Scientific and Technical Information of China (English)

    李涛; 谭多望; 李强; 谭兴春; 傅华

    2014-01-01

    块体金属玻璃具有极高的力学强度,存在潜在的军事应用价值,实现其应用的关键在于认识材料在高应变率下的动力学行为特性。为此,利用飞片驱动速度可达3.5 km/s 的电炮加载装置,对一种新制备的锆基块体金属玻璃的动力学响应进行了实验研究。实验中,基于高精度DPS激光干涉仪测得的样品/窗口界面粒子速度波剖面,获得了新材料在应变率约为106/s下的冲击响应特性参数。在加载压力15~25GPa 范围下,确定的 Hugoniot弹性极限约为2.4GPa,线性拟合得到的冲击 Hugoniot关系为Ds=(4.4±0.1)+(0.58±0.08)up。%As a novel material with high strength,bulk metallic glass received concern of many researchers all over the world.For potential military applications,it was important to un-derstand the dynamic response of this material under high strain rate.To this end,Electric Gun was chosen to study dynamic response of a newly prepared Zr-based bulk metallic glass.In the E-lectric Gun experiments,the velocity of electric explosion driven plastic flyer in 0.5 mm thick-ness could reach 3 .5 km/s.Based on bulk metallic glass sample/window interface particle veloci-ty profiles measured by high resolution DPS laser interferometer,two important dynamic behav-iors were obtained under high strain rate about 106/s.In a shock pressure range of 15~25GPa, the Hugoniot elastic limit was determined to be about 2 .4GPa,and the shock wave velocity (Ds) vs.particle velocity (up)Hugoniot data were linearly fitted by Ds= (4.4±0.1)+(0.58±0.08)up.

  17. Processing metallic glasses by selective laser melting

    Directory of Open Access Journals (Sweden)

    Simon Pauly

    2013-01-01

    Full Text Available Metallic glasses and their descendants, the so-called bulk metallic glasses (BMGs, can be regarded as frozen liquids with a high resistance to crystallization. The lack of a conventional structure turns them into a material exhibiting near-theoretical strength, low Young's modulus and large elasticity. These unique mechanical properties can be only obtained when the metallic melts are rapidly cooled to bypass the nucleation and growth of crystals. Most of the commonly known and used processing routes, such as casting, melt spinning or gas atomization, have intrinsic limitations regarding the complexity and dimensions of the geometries. Here, it is shown that selective laser melting (SLM, which is usually used to process conventional metallic alloys and polymers, can be applied to implement complex geometries and components from an Fe-base metallic glass. This approach is in principle viable for a large variety of metallic alloys and paves the way for the novel synthesis of materials and the development of parts with advanced functional and structural properties without limitations in size and intricacy.

  18. Analysis of dynamic segregation and crystallisation in Mg{sub 65}Cu{sub 25}Y{sub 10} bulk metallic glass using atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Laws, K.J., E-mail: k.laws@unsw.edu.au [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Saxey, D.W. [Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. (Australia); McKenzie, W.R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Electron Microscopy Unit, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW 2052 (Australia); Marceau, R.K.W. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Max-Planck Institut fuer Eisenforschung, Max-Planck-Str.1, Duesseldorf, D-40237 (Germany); Gun, B. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Ringer, S.P. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Ferry, M. [Australian Research Council Centre of Excellence for Design in Light Metals (Australia); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2012-10-30

    In order to develop an in-depth understanding of the flow behaviour and dynamic devitrification processes of metallic glasses in the supercooled liquid region, tensile testing of amorphous Mg{sub 65}Cu{sub 25}Y{sub 10} samples was carried out at temperatures from 150 to 170 Degree-Sign C and at strain rates from 1 Multiplication-Sign 10{sup -3} s{sup -1} to 1 Multiplication-Sign 10{sup -2} s{sup -1}. Tensile data showed a consistent and reproducible inflexion in flow stress at a particular strain that was largely independent of strain rate. This was followed by a dramatic increase in flow stress occuring prior to the determined onset times of static crystallisation. Samples were analysed using atom probe tomography and the results indicate that tensile straining of the initially homogeneous amorphous alloy results in segregation into two distinct glassy phases via a shear-related process, coincident with the maximum shear plane angle, followed by the evolution of regions corresponding to the composition of a number of equilibrium binary and ternary intermetallic phases.

  19. Third-Order Elastic Constants and Anharmonic Properties of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    WANG Ru-Ju; LI Feng-Ying; QIN Zhi-Cheng; WANG Wei-Hua

    2001-01-01

    The longitudinal velocity V1 and shear velocity Vs of an ultrasonic wave propagated along three arbitrary perpendicular directions of the Zr41.2 Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass (Zr/Ti BMG) have been measured at ambient pressure, under hydrostatic pressure (up to 0.5 GPa) and uniaxial compression (up to 70 MPa) using the pulse echo overlap method. The third-order elastic constants and the Gruneisen parameter related to the anharmonic properties were derived and discussed. It was found that the BMG with marked different microstructural characteristics, compared with the amorphous carbon, exhibited different behaviours related to shear vibratory under high pressure.

  20. Phase evolution and its effect on magnetic properties of Nd sub 6 sub 0 Al sub 1 sub 0 Fe sub 2 sub 0 Co sub 1 sub 0 bulk metallic glass

    CERN Document Server

    Lei Xia; Pan, M X; Zhao, D Q; Wang, W H; Dong, Y D

    2003-01-01

    The thermal stability of nanocrystalline clusters, the phase evolution, and their effects on magnetic properties were studied for as-cast Nd sub 6 sub 0 Al sub 1 sub 0 Fe sub 2 sub 0 Co sub 1 sub 0 alloy using differential scanning calorimetry curves, x-ray diffraction patterns, scanning electron microscopy, and high-resolution transition electron microscopy. Thermomagnetic curves and hysteresis loops of the bulk metallic glass were measured during the annealing process. The high thermostability of the hard magnetic properties of the samples observed is attributed to the stability of the nanocrystalline clusters upon annealing, while the slight enhancement in the magnetization is due to the precipitation of some Nd-rich metastable phases. The mechanism of thermostability of the nanocrystalline clusters and the formation of the metastable phases are discussed.

  1. Bulk amorphous metallic alloys: Synthesis by fluxing techniques and properties

    Energy Technology Data Exchange (ETDEWEB)

    He, Yi; Shen, Tongde; Schwarz, R.B.

    1997-05-01

    Bulk amorphous alloys having dimensions of at least 1 cm diameter have been prepared in the Pd-Ni-P, Pd-Cu-P, Pd-Cu-Ni-P, and Pd-Ni-Fe-P systems using a fluxing and water quenching technique. The compositions for bulk glass formation have been determined in these systems. For these bulk metallic glasses, the difference between the crystallization temperature T{sub x}, and the glass transition temperature T{sub g}, {Delta}T = T{sub x} - T{sub g}, ranges from 60 to 1 10 K. These large values of {Delta}T open the possibility for the fabrication of amorphous near net-shape components using techniques such as injection molding. The thermal, elastic, and magnetic properties of these alloys have been studied, and we have found that bulk amorphous Pd{sub 40}Ni{sub 22.5}Fe{sub 17.5}P{sub 20} has spin glass behavior for temperatures below 30 K. 65 refs., 14 figs., 3 tabs.

  2. Inherent Shear-Dilatation Coexistence in Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    JIANG Min-Qiang; JIANG Si-Yue; DAI Lan-Hong

    2009-01-01

    Shear deformation can induce normal stress or hydrostatic stress in metallic glasses [Nature Mater. 2 (2003) 449, Intermetallics 14 (2006) 1033]. We perform the bulk deformation of three-dimensional Cu46Zr54 metallic glass (MG) and Cu single crystal model systems using molecular dynamics simulation. The results indicate that hydrostatic stress can incur shear stress in MG, but not in crystal. The resultant pronounced asymmetry between tension and compression originates from this inherent shear-dilatation coexistence in MG.

  3. Metallic glasses: properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Dugdale, J.S.; Pavuna, D.; Rhodes, P.

    1985-01-01

    Metallic glasses are a class of disordered materials that contrast with crystalline metals and provide a new challenge to theories of electronic structure and magnetic interactions in solids. Their study will undoubtedly broaden and deepen our understanding of the solid state. In addition, they are now finding a wide variety of technological applications. Some of these applications as well as their magnetic properties are presented here. 7 references, 3 figures, 1 table.

  4. Role of crystalline precipitates on the mechanical properties of (Cu{sub 0.50}Zr{sub 0.50}){sub 100-x}Al{sub x} (x = 4, 5, 7) bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Castellero, A., E-mail: alberto.castellero@unito.it [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy); Baser, T.A. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy); EMPA - Swiss Federal Laboratories for Materials Testing and Research, Duebendorf (Switzerland); Das, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstr. 20, D-01069 Dresden (Germany); Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721 302, West Bengal (India); Matteis, P. [DISMIC - Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstr. 20, D-01069 Dresden (Germany); TU Dresden, Institut fuer Werkstoffwissenschaft, D-01062 Dresden (Germany); Battezzati, L.; Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy)

    2011-06-15

    Research highlights: > The glass formation reproducibility of (Cu{sub 0.50}Zr{sub 0.50}){sub 100-x}Al{sub x} (x = 4,5,7) was investigated. > X-ray amorphous Cu{sub 48}Zr{sub 48}Al{sub 4} samples contain up to 20% of B2-CuZr crystals. > Fracture strain scales directly with the amount of the B2-CuZr crystalline phase. > Spread in literature values of fracture strain for these alloys is likely due to the presence of undetected crystals. > Mechanical properties reliability can be improved by sample surface finishing. - Abstract: The mechanical behaviour upon compression of (Cu{sub 0.50}Zr{sub 0.50}){sub 100-x}Al{sub x} (x = 4, 5, 7) rods with 2 and 3 mm diameter was systematically studied and compared with the literature data. Fully amorphous bulk metallic glasses (x = 5, 7) show little permanent deformation and reproducible yield stress values. The remarkable fracture strain, observed for some apparently X-ray diffraction amorphous samples (x = 4), was found to be due to significant amounts (at least 20%) of the B2-CuZr crystalline phase. The effect of possible flaws on the external surface of the rods was evaluated by mechanical testing of either as cast and machined samples.

  5. Sink property of metallic glass free surfaces.

    Science.gov (United States)

    Shao, Lin; Fu, Engang; Price, Lloyd; Chen, Di; Chen, Tianyi; Wang, Yongqiang; Xie, Guoqiang; Lucca, Don A

    2015-03-16

    When heated to a temperature close to glass transition temperature, metallic glasses (MGs) begin to crystallize. Under deformation or particle irradiation, crystallization occurs at even lower temperatures. Hence, phase instability represents an application limit for MGs. Here, we report that MG membranes of a few nanometers thickness exhibit properties different from their bulk MG counterparts. The study uses in situ transmission electron microscopy with concurrent heavy ion irradiation and annealing to observe crystallization behaviors of MGs. For relatively thick membranes, ion irradiations introduce excessive free volumes and thus induce nanocrystal formation at a temperature linearly decreasing with increasing ion fluences. For ultra-thin membranes, however, the critical temperature to initiate crystallization is about 100 K higher than the bulk glass transition temperature. Molecular dynamics simulations indicate that this effect is due to the sink property of the surfaces which can effectively remove excessive free volumes. These findings suggest that nanostructured MGs having a higher surface to volume ratio are expected to have higher crystallization resistance, which could pave new paths for materials applications in harsh environments requiring higher stabilities.

  6. Recent results on bulk laser damage threshold of optical glasses

    Science.gov (United States)

    Jedamzik, Ralf; Elsmann, Frank

    2013-02-01

    Modern pulsed laser applications cover a broad range of wavelength, power and pulse widths. Beam guiding optics in laser systems do not only have specific requirements on the imaging quality but also have to withstand high laser power. The laser damage threshold of an optical component depends on the surface (polishing, coating ...) and also on the bulk material properties. Actual values of bulk laser damage thresholds, particularly at pulse lengths less than 1 nanosecond (1 ns), of optical glasses are rarely found in literature, except for fused silica, which is known as a key optical material for components in high power laser. However, fused silica is rather expensive and limited in optical properties. That is the reason why customers often ask for laser damage threshold data of optical glasses. Therefore, SCHOTT has started a project for the characterization of the bulk laser damage threshold of optical glasses at the wavelengths 532 nm and 1064 nm with pulse lengths in the nano- and pico-second range. Bulk and surface laser damage testing has been performed by the Laser Zentrum Hannover in Germany according to the S-on-1 test of DIN EN ISO 11254-2 / DIN EN ISO 21254.

  7. Quasistatic and Dynamic Tensile Behavior of Zr52.5Al10Ni10Cu15Be12.5 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    Xueshan XIAO; Weihuo LI; Lei XIA; Shoushi FANG; Qin HUA; Yuanda DONG

    2003-01-01

    Quasistatic and dynamic tensile behavior of Zr52.5Al10Ni10Cu15Be12.5 bulk amorphous alloy was investigated at the strain ratesof 10-4~103 s-1 by using a Shimadzu AG-100KNA autograph and a pneumatic tensile impact tester. It was shown that thetensile fracture strength and the fracture morphology were sensitive to the strain rate. With the increase of the strain rate,the tensile fracture strength decreased and the fracture morphology changed from cleavage into quasi-cleavage, and then intoa mixture of microvoid-coalescence dimples and quasi-cleavage veins.

  8. Production of glass or glass-ceramic to metal seals with the application of pressure

    Science.gov (United States)

    Kelly, M.D.; Kramer, D.P.

    1985-01-04

    In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

  9. Failure by fracture in bulk metal forming

    DEFF Research Database (Denmark)

    Silva, C.M.A.; Alves, Luis M.; Nielsen, Chris Valentin

    2015-01-01

    This paper revisits formability in bulk metal forming in the light of fundamental concepts of plasticity,ductile damage and crack opening modes. It proposes a new test to appraise the accuracy, reliability and validity of fracture loci associated with crack opening by tension and out-of-plane she...

  10. Composition-dependent metallic glass alloys correlate atomic mobility with collective glass surface dynamics.

    Science.gov (United States)

    Nguyen, Duc; Zhu, Zhi-Guang; Pringle, Brian; Lyding, Joseph; Wang, Wei-Hua; Gruebele, Martin

    2016-06-22

    Glassy metallic alloys are richly tunable model systems for surface glassy dynamics. Here we study the correlation between atomic mobility, and the hopping rate of surface regions (clusters) that rearrange collectively on a minute to hour time scale. Increasing the proportion of low-mobility copper atoms in La-Ni-Al-Cu alloys reduces the cluster hopping rate, thus establishing a microscopic connection between atomic mobility and dynamics of collective rearrangements at a glass surface made from freshly exposed bulk glass. One composition, La60Ni15Al15Cu10, has a surface resistant to re-crystallization after three heating cycles. When thermally cycled, surface clusters grow in size from about 5 glass-forming units to about 8 glass-forming units, evidence of surface aging without crystal formation, although its bulk clearly forms larger crystalline domains. Such kinetically stable glass surfaces may be of use in applications where glassy coatings stable against heating are needed.

  11. The effect of high temperature plastic deformation on the thermal stability and microstructure of Zr{sub 55}Cu{sub 30}Ni{sub 5}Al{sub 10} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)], E-Mail: lliu2000@public.wh.hb.cn; Chen, Q. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Chan, K.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University, Hong Kong (China); Wang, J.F. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Pang, G.K.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2007-03-25

    The plastic deformation of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} (numbers indicate at.%) bulk metallic glass (BMG) was conducted in the supercooled liquid region under uniaxial tension with various strain rates ranging from 8.3 x 10{sup -4} to 2 x 10{sup -2} s{sup -1}. It was found that the deformation behavior of the BMG is strongly dependent on strain rate. Thermal and structural investigations revealed that the plastic deformation reduced the thermal stability of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} BMG and promoted crystallization or reordering of the amorphous structure. To clarify the correlation between strain and structure of the BMG, the sample that was deformed at a high strain rate and exhibited significant necking was selected for a detailed investigation of its structure in different parts (e.g., the tip, middle and end parts) by conventional and high-resolution transmission electron microscopy. It was found that a band crystalline structure with a strongly crystallographic orientation was formed at the tip part, while inhomogeneous nanocrystallization occurred in the middle parts, and the amorphous structure remained almost unchanged in the end part. The different structures observed in different parts of the deformed sample are attributed to the inhomogeneous deformation of the BMG at high strain rates.

  12. Structure and Properties of Mg-Cu-(Y,Ca Bulk Metallic Glasses / Struktura I Własności Masywnych Szkieł Metalicznych Mg-Cu-(Y,Ca

    Directory of Open Access Journals (Sweden)

    Babilas R.

    2015-12-01

    Full Text Available The work presents preparation methods, structure characterization and mechanical properties analysis of Mg-based bulk metallic glasses in as-cast state and after crystallization process. The studies were performed on Mg60Cu30Y10 and Mg37Cu36Ca27 glassy alloys in the form of plates and rods. The X-ray diffraction investigations revealed that the tested samples with different thicknesses and shapes were amorphous. The characteristics of the fractured surfaces showed mixed fractures with the “river” and “mirror” patterns, which are characteristic for the glassy materials and some “smooth” areas. The samples of Mg37Cu36Ca27 alloy presented a two-stage crystallization process, but addition of Y caused a single stage crystallization behavior. Qualitative phase analysis from the X-ray data of examined alloys annealed at 473 K enabled the identification of Mg, Mg2Cu, Cu2Mg and CaCu crystalline phases. The changes of compressive strength as a function of annealing temperature for studied rods were stated. The best mechanical properties including microhardness and compressive strength were obtained for the alloy with the addition of Y in as-cast state.

  13. Homogeneous Plastic Flow of Fully Amorphous and Partially Crystallized Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    Q.WANG; J.J. Blandin; M. Suery; B. Van de Moortéle; J.M. Pelletier

    2003-01-01

    The homogeneous plastic flow of fully amorphous and partially crystallized Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass (Vit1) has been investigated by compression tests at high temperatures in supercooled liquid region. Experimental results show that at sufficiently low strain rates, the supercooled liquid of the fully amorphous alloy reveals Newtonian flow with a linear relationship between the flow stress and strain rate. As the strain rate is increased, a transition from linear Newtonian to nonlinear flow is detected, which can be explained by the transition state theory.Over the entire strain rate interval investigated, however, only nonlinear flow is present in the partially crystallized alloy, and the flow stress for each strain rate is much higher. It is found that the strain rate-stress relationship for the partially crystallized alloy at the given temperature of 646 K also obeys the sinh law derived from the transition state theory, similar to that of the initial homogeneous amorphous alloy. Thus, it is proposed that the flow behavior of the nanocrystalline/amorphous composite at 646 K is mainly controlled by the viscous flow of the remaining supercooled liquid.

  14. On the origin of bulk glass forming ability in Cu-Hf, Zr alloys

    Science.gov (United States)

    Ristić, Ramir; Zadro, Krešo; Pajić, Damir; Figueroa, Ignacio A.; Babić, Emil

    2016-04-01

    Understanding the formation of bulk metallic glasses (BMG) in metallic systems and finding a reliable criterion for selection of BMG compositions are among the most important issues in condensed-matter physics and material science. Using the results of magnetic susceptibility measurements performed on both amorphous and crystallized Cu-Hf alloys (30-70 at% Cu) we find a correlation between the difference in magnetic susceptibilities of corresponding glassy and crystalline alloys and the variation in the glass forming ability (GFA) in these alloys. Since the same correlation can be inferred from data for the properties associated with the electronic structure of Cu-Zr alloys, it seems quite general and may apply to other glassy alloys based on early and late transition metals. This correlation is plausible from the free-energy considerations and provides a simple way to select the compositions with high GFA.

  15. Copper phthalocyanine and metal free phthalocyanine bulk heterojunction photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Farooq, Amjad, E-mail: amjad.farooq1212@hotmail.com [Wah Engineering College, University of Wah, Wah Cantt. 47040 (Pakistan); GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Karimov, Kh.S. [GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Physical Technical Institute, Aini St. 299/1, Dushanbe 734063 (Tajikistan); Ahmed, Nisar; Ali, Taimoor [GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Khalid Alamgir, M. [National Institute of Vacuum Science and Technology, NCP complex, Islamabad 44000 (Pakistan); Usman, Muhammad [Experimental Physics Laboratories, National Centre for Physics, Quaid-i-Azam University, Islamabad 44000 (Pakistan)

    2015-01-15

    In this study we present the dependence of electrical properties of copper phthalocyanine (CuPc) and metal free phthalocyanine (H{sub 2}Pc) bulk heterojunction structure under different illumination levels. To fabricate the device on ITO coated glass substrate the bulk heterojunction thin film of CuPc and H{sub 2}Pc with thickness varying from 100 nm to 300 nm are deposited by thermal evaporator. Aluminum thin film was deposited by thermal evaporation as a top contact. The optical properties of the fabricated device are investigated using UV–vis spectroscopy. The current-voltage characteristics in dark and under illumination show that the device is sensitive towards visible light. The absorption spectrum describes its photo sensitivity in the range of wavelength from 200 nm to 850 nm. Simulation of current-intensity of light curve is carried out and experimental results are found in good agreement with simulated ones.

  16. Producing Magnesium Metallic Glass By Disintegrated Melt Deposition

    Science.gov (United States)

    Shanthi, M.; Gupta, M.; Jarfors, A. E. W.; Tan, M. J.

    2011-01-01

    Bulk metallic glasses are new class of engineering materials that exhibit high resistance to crystallization in the under cooled liquid state. The development of bulk metallic glasses of thickness 1cm or less has opened new doors for fundamental studies of both liquid state and glass transition previously not feasible in metallic materials. Moreover, bulk metallic glasses exhibit superior hardness, strength, specific strength, and elastic strain limit, along with good corrosion and wear resistance. Thus they are potential candidates in various sports, structural, engineering and medical applications. Among several BMGs investigated, magnesium-based BMGs have attracted considerable attention because of their low density and superior mechanical properties. The major drawback of this magnesium based BMGs is poor ductility. This can be overcome by the addition of ductile particles/reinforcement to the matrix. In this study, a new technique named disintegrated melt deposition technique was used to synthesize magnesium based BMGs. Rods of different sizes are cast using the current method. Mechanical characterization studies revealed that the amorphous rods produced by the current technique showed superior mechanical properties.

  17. 基于团簇和胶粘原子模型的(Fe-Ni)-B-Y-Nb块体非晶合金%(Fe-Ni)-B-Y-Nb Bulk Metallic Glasses Based on the Model of Clusters and Glue Atoms

    Institute of Scientific and Technical Information of China (English)

    陈伟荣; 韩光; 陈季香; 朱春雷; 王清; 王英敏; 董闯

    2011-01-01

    应用团簇+胶粘原子模型在三元Fe-B-Y合金系中设计三元合金成分,选择最密堆的CN10 Archimedes八面体反棱柱FesB作为基本团簇,Y为胶粘原子.在此基础上添加3at%Nb作为微合金化元素形成四元合金.以适量的Ni替换Fe,形成五元合金[(Fie100-xNix)B-Y]-Nb.结果表明,当Ni的含量小于30at%时,均可形成直径为2 mm的块体非晶合金,其中,合金[(FeNi)B-Y]-Nb 具有最大的Tg、Tx和Trg值,分别为:884K、972K和0.634.%Using the model of cluster + glue atom, the temary bulk metallic glasses (BMG) in Fe-B-Y system was designed, choosing the close-packed Archimedes octahedral antiprism CN-10 FeaB3 as basic cluster and Y as glue atom.3at%Nb was added as minor alloying element to form quatemary BMG Ni was used to substitute for Fe, and a quinary BMG [(Fe100-xNix)8B3-Y]97-Nb3, was formed.Results show that when Ni is less than 30at% the BMG with diameter of 2 mm can be obtained and the alloy [(Fe94Ni6)8B3-Y]97-Nb3 has the biggest Tg, Tx; and Trg which are 884 K, 972 K and 0.634, respectively.

  18. Non-isothermal crystallization kinetics and glass-forming ability of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} bulk metallic glass investigated by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Pan; Zhao, Shaofan; Yao, Kefu [Tsinghua University, School of Materials Science and Engineering, Beijing (China); Wang, Xin [Hebei University of Technology, School of Materials Science and Engineering, Tianjin (China)

    2015-07-15

    The non-isothermal crystallization kinetics and glass-forming ability of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} alloy can be classified as ''strong glass former.'' The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} glassy alloy has also been determined using Barandiaran-Colmenero's method. (orig.)

  19. Effect of Cu addition on nanocrystallization behaviors and magnetic properties of the Fe{sub 76.5−x}C{sub 6.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7}Cu{sub x} (x = 0–3 at.%) bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H.Y. [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Yi, S., E-mail: yish@knu.ac.kr [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2013-06-05

    Highlights: ► Effect of Cu on the modification of primary phase of soft magnetic nanocrystalline alloys. ► Soft magnetic nanocrystalline alloys with amorphous precursor having high glass forming ability. ► Enhancement of glass forming ability with small amount of Cu addition. -- Abstract: The effect of Cu addition on the glass forming ability, nanocrystallization process and soft magnetic properties of the Fe{sub 76.5}C{sub 6.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} bulk metallic glass has been studied. In spite of relatively high C contents of the alloy, with only 0.5% Cu addition, the primary phase was successfully changed from metastable carbide Fe{sub 23}C{sub 6} phase to stable alpha-Fe phase and the nucleation rate at the early stage of crystallization was significantly increased. Nanocrystallization of the Fe{sub 76.0}C{sub 6.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7}Cu{sub 0.5} (at.%) bulk metallic glass was studied through isothermal annealing treatments at temperature below the crystallization temperature of the alloy. With annealing at T{sub x} − 50 °C for 30 min, a large number of very fine regions (<3 nm) with ordered atomic arrangements embedded in the amorphous matrix were observed. Upon further annealing, nanocrystals of alpha-Fe phase were formed improving soft magnetic properties of the sample, which confirms the soft magnetic nanocrystallization phenomenon in Fe{sub 76.0}C{sub 6.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7}Cu{sub 0.5} (at.%) bulk metallic glass. By controlling the annealing parameters as well as minor Cu contents, magnetic properties of the Fe{sub 76.5}C{sub 6.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} (at.%) bulk metallic glass were effectively optimized for practical applications.

  20. A route to transparent bulk metals

    KAUST Repository

    Schwingenschlögl, Udo

    2012-07-23

    Hypothetical compounds based on a sapphire host are investigated with respect to their structural as well as electronic features. The results are obtained by electronic structure calculations within density functional theory and the generalized gradient approximation. A quarter of the Al atoms in Al 2O 3 is replaced by a 4d transition metal M ion, with d 0 to d 9 electronic configuration. We perform structure optimizations for all the compounds and analyze the electronic states. Due to the sizeable band gap of the Al 2O 3 host, we can identify promising candidates for transparent bulk metals. We explain the mechanisms leading to this combination of materials properties. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. ZrCuNiAl块体非晶合金的低温压缩变形行为%Compressive deformation behavior of ZrCuNiAl bulk metallic glass at low temperature

    Institute of Scientific and Technical Information of China (English)

    孙亚娟; 翟延慧

    2016-01-01

    Low temperature compression tests for the Zr 55.7 Cu23 Ni9 Al12.3 bulk metallic glass ( BMG) were carried out at the strain rate of 4 × 10 -4 s-1 and at the temperature of 143 K on Instron 5500 universal-testing machine , and the compressive deformation behavior of the Zr55.7 Cu23 Ni9 Al12.3 BMG during low temperature compression was investigated .The results show that the compressive yield strength and plasticity of the Zr55.7 Cu23 Ni9 Al12.3 BMG improve as testing temperature decreasing from 298 K to 143 K.Meanwhile, the phenomenon of ductile-to-brittle transition ( DBT) in traditional crystalline material is not observed with the decrease of temperature .The increase of yield strength is attributed to the nucleation of shear bands which requires a higher applied load at low temperature .Dense and multiple shear bands which are contributed to the enhanced ductility are observed on the side surface of the low temperature fractured samples .%采用Instron 5500万能试验机对Zr55.7 Cu23 Ni9 Al12.3块体非晶合金进行了应变速率为4×10-4 s-1、环境温度为143 K的低温压缩试验,研究了其低温压缩变形行为。结果表明,当测试环境温度从298 K(室温)降低到143 K时,该合金的强度和塑性均呈增加的趋势,且未出现传统晶态材料的冷脆性现象。分析表明,其屈服强度的增加源于低温下剪切带的形核需要更高的载荷,而低温下断口侧面高密度剪切带的形成导致了其塑性的增加。

  2. Failure Prediction in Bulk Metal Forming Process

    Directory of Open Access Journals (Sweden)

    Ameen Topa

    2014-01-01

    Full Text Available An important concern in metal forming is whether the desired deformation can be accomplished without defects in the final product. Various ductile fracture criteria have been developed and experimentally verified for a limited number of cases of metal forming processes. These criteria are highly dependent on the geometry of the workpiece and cannot be utilized for complicated shapes without experimental verification. However, experimental work is a resource hungry process. This paper proposes the ability of finite element analysis (FEA software such as LS-DYNA to pinpoint the crack-like flaws in bulk metal forming products. Two different approaches named as arbitrary Lagrangian-Eulerian (ALE and smooth particle hydrodynamics (SPH formulations were adopted. The results of the simulations agree well with the experimental work and a comparison between the two formulations has been carried out. Both approximation methods successfully predicted the flow of workpiece material (plastic deformation. However ALE method was able to pinpoint the location of the flaws.

  3. Glass Forming Ability of Metallic Glasses Evaluated by a New Criterion

    Institute of Scientific and Technical Information of China (English)

    CAO Qing-Ping; LI Jin-Fu; ZHOU Yao-He

    2008-01-01

    The glass-forming ability (GFA) of Cu-Zr binary alloys is evaluated using the existing criteria based on calorimetric parameters, and poor relations are found. Therefore, another parameter Trk defined as Tk/Tl, in which Tk is the Kauzmann temperature and Tl the equilibrium liquidus temperature, is proposed. It exhibits good agreements with the experimental data of the Cu-Zr system and other representative bulk metallic glass formers so long as classifying them into strong or fragile category. It is suggested that kinetic effects are irrelevantly incorporated in the GFA analysis in the previous work.

  4. Magnetic power losses in [(Fe{sub 1-x}Co{sub x}){sub 75}B{sub 20}Si{sub 5}]{sub 93}Nb{sub 4}Y{sub 3} (x = 0, 0.2, 0.4) bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Piccin, R; Baricco, M [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P.Giuria 9, 10125 Torino (Italy); Tiberto, P [Istituto Nazionale di Ricerca Metrologica INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Chiriac, H, E-mail: rafael.piccin@unito.i [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd, Iasi 700050 (Romania)

    2009-01-01

    Magnetic power losses of [(Fe{sub 1-x}Co{sub x}){sub 75}B{sub 20}Si{sub 5}]{sub 93}Nb{sub 4}Y{sub 3} (x = 0, 0.2, 0.4) metallic glasses have been investigated. Bulk samples were prepared by water-cooled Cu-mold injection casting technique with shapes of cylinders (0.8 mm diameter and 30 mm length) and toroids (10 mm external diameter and 0.5 mm thickness). Ribbons prepared by the melt- spinning technique were also analyzed. Glassy structures were confirmed by the presence of a main halo in XRD and by crystallization signal in DSC. Power losses were studied with a digital wattmeter over a range of frequencies from 1 to 400 Hz at selected peak inductions. Ribbons show smaller losses than bulk samples, presenting 24.5 J/m{sup 3} at 50 Hz and 0.65 T peak induction. It was observed that the Co addition reduces significantly the power losses. A separation theory was applied in order to explain the square root behavior of the measured power losses as a function of frequency and the results are in good agreement with the experimental data. The magnetic data were used to identify the presence of crystalline inclusions in the magnetic bulk metallic glasses. The effect of sample shape and composition on magnetic properties will be discussed.

  5. Shaping metallic glasses by electromagnetic pulsing

    Science.gov (United States)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-02-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  6. Shaping metallic glasses by electromagnetic pulsing

    Science.gov (United States)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-01-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

  7. Advanced and new developments in bulk metal forming

    DEFF Research Database (Denmark)

    Bay, Niels; Wanheim, Tarras; Ravn, Bjarne Gottlieb;

    2000-01-01

    Increasing demands to manufacturing industry of faster, better and cheaper production has intensified the research and development of bulk metal forming. The present paper gives examples on European industrial research on secondary bulk metal forming processes. The R&D follows three lines of appr...

  8. Low Temperature Heat Capacity of a Severely Deformed Metallic Glass

    Science.gov (United States)

    Bünz, Jonas; Brink, Tobias; Tsuchiya, Koichi; Meng, Fanqiang; Wilde, Gerhard; Albe, Karsten

    2014-04-01

    The low temperature heat capacity of amorphous materials reveals a low-frequency enhancement (boson peak) of the vibrational density of states, as compared with the Debye law. By measuring the low-temperature heat capacity of a Zr-based bulk metallic glass relative to a crystalline reference state, we show that the heat capacity of the glass is strongly enhanced after severe plastic deformation by high-pressure torsion, while subsequent thermal annealing at elevated temperatures leads to a significant reduction. The detailed analysis of corresponding molecular dynamics simulations of an amorphous Zr-Cu glass shows that the change in heat capacity is primarily due to enhanced low-frequency modes within the shear band region.

  9. 铁基块体非晶合金玻璃形成能力与特征自由体积的关系%CORRELATION BETWEEN THE GLASS-FORMING ABILITY AND CHARACTERISTIC FREE VOLUMES OF THE IRON BASE BULK METALLIC GLASSES

    Institute of Scientific and Technical Information of China (English)

    胡强; 曾燮榕; 钱海霞; 谢胜辉; 盛洪超

    2012-01-01

    Many researches have demonstrated that the free volume have a great effect on the properties of bulk metallic glasses (BMGs). For different BMGs, however, quantitative measurement of free volumes and analysis of properties of BMGs using the measurement results are still difficult. In this work, the two types of characteristic free volumes, the free volume released in structural relaxation, △Vf-sr and the free volume generated in glass transition, △Vf_gt are given from the △(dV(T)/V0) curve, where the △(dV(T)/V0) is the thermal expansion difference between amorphous and crystalline samples measured by a cyclic thermal dilation test. In a series of Fe-(Er)-Cr-Mo-C-B BMGs, it is found that the BMG with the largest critical diameter (Dc) has also the largest △Vf_gt, and Dc increases sensitively with the decrease of △Vf-sr. More impressively, D2c or Dc can be fitted with high regression coefficient of 0.998 by a negative exponential function of △Vf-sr- Hence, the characteristic free volume has a sensitive and close correlation with the glass forming ability of BMGs.%运用循环热膨胀法获得了块体非晶合金与其晶态合金的体膨胀差曲线△(dV(T)/Vo),由此定义出块体非晶合金的2个特征自由体积,即结构弛豫中释放出的自由体积△Vf-sr和玻璃转变中生成的自由体积△Vf-gt.Fe-(Er)-Cr-Mo-C-B系列块体非晶合金的实验结果表明:非晶合金的玻璃形成能力与其特征自由体积关系密切,临界尺寸Dc最大的非晶合金的△Vf-gt也最大;且Dc随△Vf-sr变化趋势明显,D2c或Dc可以拟合成△Vf-sr的负指数函数,回归系数高达0.998.

  10. Bioactive glass coatings for orthopedic metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Esteban, Sonia; Saiz, Eduardo; Fujino, Sigheru; Oku, Takeo; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-06-30

    The objective of this work is to develop bioactive glass coatings for metallic orthopedic implants. A new family of glasses in the SiO2-Na2O-K2O-CaO-MgO-P2O5 system has been synthesized and characterized. The glass properties (thermal expansion, softening and transformation temperatures, density and hardness) are in line with the predictions of established empirical models. The optimized firing conditions to fabricate coatings on Ti-based and Co-Cr alloys have been determined and related to the glass properties and the interfacial reactions. Excellent adhesion to alloys has been achieved through the formation of 100-200 nm thick interfacial layers (Ti5Si3 on Ti-based alloys and CrOx on Co-Cr). Finally, glass coatings, approximately 100 mu m thick, have been fabricated onto commercial Ti alloy-based dental implants.

  11. Liquid -to-glass transition in bulk glass-forming Cu55-xZr45Agx alloys using molecular dynamic simulations

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available We report results from molecular dynamics (MD studies concerning the microscopic structure of the ternary, bulk metallic glass-forming Cu55-x Zr45Agx (x=0,10,20 alloys using tight-binding potentials. Understanding of the nature of Glass Forming Ability (GFA of studied alloys, GFA parameters, glass transition temperature (T-g, melting temperature (T-m, reduced glass transition temperature (T-g/T-m, the supercooled liquid region and other parameters were simulated and compared with experiments. The computed pair distribution functions reproduce well experimental x-ray data of Inoue and co-workers. Structure analysis of the Cu-Zr-Ag alloy based on MD simulation will be also presented

  12. Comparing the density of states of binary Lennard-Jones glasses in bulk and film

    Science.gov (United States)

    Ghosh, Jayeeta; Faller, Roland

    2008-03-01

    We used Wang-Landau density of states Monte Carlo to study a binary Lennard-Jones glass-forming mixture in bulk and films between noninteracting walls. Thermodynamic properties are calculated using two different ensembles and film data are compared with the bulk. Bulk properties are in good agreement with previous simulations. We confirm the formation of a glass using various properties, e.g., energy, heat capacity, and pressure with temperature. We find a change in slope in the energy per particle and pressure as a function of temperature. We do not find any defined crystal structure. A higher glass transition temperature is found for the film.

  13. 牙科用微弧氧化后锆基非晶合金的组织相容性研究%Histocompatibility evaluation of Zr-based bulk metallic glass with micro-arc oxidation for dental restoration

    Institute of Scientific and Technical Information of China (English)

    王芳; 程翔; 刘桂英; 马越; 孙英博; 曹尤雅; 孙宇

    2016-01-01

    Objective Oral mucosa irritation and subcutaneous implantation tests were launched to study the histocompatibility of mi⁃cro⁃arc oxidized Zr⁃Cu⁃Al⁃Ag bulk metallic glass ( BMG) . Methods Referring to the standard of ISO 10993⁃6:1994, micro⁃arc oxi⁃dized BMG and titanium alloy samples with dimension ofΦ5 mm×0.5 mm for oral mucosa irritation andΦ1.5 mm×5 mm for subcutane⁃ous implantation were prepared, respectively. Results The result of oral mucous membrane irritation test showed that all samples did not have local or systemic adverse reactions and the histopathological findings were also normal;the subcutaneous implant test displayed that the Zr⁃Cu⁃Al⁃Ag alloy had no apparent toxicity. After specimens were implanted for one week, local tissue was found to be slightly red and swollen, and the biopsies showed a few of inflammatory cells;4 and 12 weeks later, it was showed that the inflammatory re⁃sponse gradually reduced as time prolonged, with the formation process of looser fiber coat. The micro⁃arc oxidized Zr⁃base BMG was coated by fiber which was looser than the experimental group. Conclusion As a new type of dental implant materials, the performance of Zr⁃base BMG is excellent, but its biological inert hinders the application of this material, micro⁃arc oxidation treatment effectively re⁃duces the biological inert of Zr⁃base BMG, maintains the excellent properties of Zr⁃base BMG, and can give good histocompatibility to Zr⁃based BMG at the same time.%目的:通过进行口腔黏膜刺激实验和皮下植入实验,研究微弧氧化后锆基非晶合金的组织相容性。方法实验参照ISO 10993⁃6:1994标准,分别将微弧氧化前后的锆基非晶合金和对照用的钛合金制备成直径5 mm,厚0.5 mm的圆片样品和直径1.5 mm,长5 mm的柱状样品,进行口腔黏膜刺激实验和皮下植入实验。结果口腔黏膜刺激实验未出现全身及局部不良反应,组织学

  14. Nucleation and growth of a multicomponent metallic glass@

    Indian Academy of Sciences (India)

    Arun Pratap; K G Raval; Ajay Gupta; S K Kulkarni

    2000-06-01

    The metallic glass samples of Fe67Co18B14Si1 (2605CO), prepared by the melt spinning technique were procured from the Allied Corporation. The kinetics of crystallization of this multicomponent glassy alloy is studied using differential scanning calorimetry (DSC). The crystallization data have been examined in terms of modified Kissinger and Matusita equations for the non-isothermal crystallization. The results show enhanced bulk nucleation in general. At high heating rates added to it is surface induced abnormal grain growth resulting in fractal dimensionality.

  15. On the kinetic and thermodynamic fragility of the Pt{sub 60}Cu{sub 16}Co{sub 2}P{sub 22} and Pt{sub 57.3}Cu{sub 14.6}Ni{sub 5.3}P{sub 22.8} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gallino, Isabella, E-mail: i.gallino@mx.uni-saarland.de [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany); Gross, Oliver [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany); Dalla Fontana, Giulia [Department of Chemistry IFM and NIS, University of Torino, V. Giuria 7, 10125 Torino (Italy); Evenson, Zach; Busch, Ralf [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany)

    2014-12-05

    Highlights: • The studied Pt–Cu–(Ni,Co)–P glasses are more fragile than Zr-based alloys. • They show large increases in the C{sub p} at T{sub g} and small barriers for cooperative rearrangements of atoms. • They have fragility parameters among the lowest reported for BMG systems (D{sup *} = 10–12). • They crystallize into a state that melts with distinctly high entropy of fusion. • The microscopic origin of their fragility seems different than that for Zr- and Pd-based BMGs. - Abstract: The investigations in this study focus on bulk metallic glass (BMG) alloy families based on noble metals like Pt, which are more kinetically fragile than Zr-based BMG systems. Thermophysical properties have been investigated by calorimetry and thermal mechanical analyses for the determination of the specific heat capacity and viscosity, respectively. For the Pt{sub 60}Cu{sub 16}Co{sub 2}P{sub 22} and Pt{sub 57.3}Cu{sub 14.6}Ni{sub 5.3}P{sub 22.8} BMG compositions consistent Vogel–Fulcher–Tammann (VFT) fits of the viscosity measurements are established, and the temperature dependence of the configurational entropy is calculated from thermodynamic data. Fits to the Adam–Gibbs equation are performed using this configurational entropy change. Their fragile nature is compared to that of Zr-based alloys in terms of structural considerations.

  16. Calculated Bulk Properties of the Actinide Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Andersen, O. K.; Johansson, B.

    1978-01-01

    Self-consistent relativistic calculations of the electronic properties for seven actinides (Ac-Am) have been performed using the linear muffin-tin orbitals method within the atomic-sphere approximation. Exchange and correlation were included in the local spin-density scheme. The theory explains...... the variation of the atomic volume and the bulk modulus through the 5f series in terms of an increasing 5f binding up to plutonium followed by a sudden localisation (through complete spin polarisation) in americium...

  17. Effective temperature dynamics of shear bands in metallic glasses

    Science.gov (United States)

    Daub, Eric G.; Klaumünzer, David; Löffler, Jörg F.

    2014-12-01

    We study the plastic deformation of bulk metallic glasses with shear transformation zone (STZ) theory, a physical model for plasticity in amorphous systems, and compare it with experimental data. In STZ theory, plastic deformation occurs when localized regions rearrange due to applied stress and the density of these regions is determined by a dynamically evolving effective disorder temperature. We compare the predictions of STZ theory to experiments that explore the low-temperature deformation of Zr-based bulk metallic glasses via shear bands at various thermal temperatures and strain rates. By following the evolution of effective temperature with time, strain rate, and temperature through a series of approximate and numerical solutions to the STZ equations, we successfully model a suite of experimentally observed phenomena, including shear-band aging as apparent from slide-hold-slide tests, a temperature-dependent steady-state flow stress, and a strain-rate- and temperature-dependent transition from stick-slip (serrated flow) to steady-sliding (nonserrated flow). We find that STZ theory quantitatively matches the observed experimental data and provides a framework for relating the experimentally measured energy scales to different types of atomic rearrangements.

  18. Festival of Metal-Glass Furniture

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Along with the increasing demand in China's real estate, require-ments on house decoration raise the taste as well. Nowadays, fur-niture is far more than what we see in grand-ma's living room. Metal furniture attracts many eyeballs because of its shinning luster. From September 16 to 18, a special fair in metal-glass furniture was held in Shengfang International Furniture Centre, Shengfang Town, Bazhou City, Hebei Province, and it was the second session of the fair already. And the first session was held in the same date of last year.

  19. Kinetics of glass transition and crystallization in multicomponent bulk amorphous alloys

    Institute of Scientific and Technical Information of China (English)

    庄艳歆[1; 赵德乾[2; 张勇[3; 汪卫华[4; 潘明祥[5

    2000-01-01

    Differential scanning calorimeter (DSC) is used to investigate apparent activation energy of glass transition and crystallization of Zr-based bulk amorphous alloys by Kissinger equation under non-isothermal condition. It is shown that the glass transition behavior as well as crystallization reaction depends on the heating rate and has a characteristic of kinetic effects. After being isothermally annealed near glass transition temperature, the apparent activation energy of glass transition increases and the apparent activation energy of crystallization reaction decreases. However, the kinetic effects are independent of the pre-annealing.

  20. Study on microstructure and mechanical properties of Ti66.7Ni20CU13.3 bulk metallic glass%Ti66.7Ni20Cu13.3非晶复合材料的组织和力学性能研究

    Institute of Scientific and Technical Information of China (English)

    赵燕春; 寇生中; 李春燕; 蒋维科; 李超

    2013-01-01

    We proposed the composite strengthening and toughening technology routin, to develep the in-situ formed bulk metallic glass matrix composites toughened by the precipitation soft supercooled austenitic phase, and strengthened by deformation induced martensitic transformation of the supercooled austenite in shape-mem-ory crystals. The effect of cooling rate on microstructure and mechanical properties of Ti66.7Ni20Cu13.3 bulk me-tallic glasses matrix composites was investigated. The results show that the shape-memory supercooled austen-ite crystals B2-TiNi and some brittle intermetallics phases separate on the armophous matrix. And the final fracture is controlled by the competition of the martensite phase and brittle crystallizing phases.%选择具有非晶形成能力和形状记忆效应的Ti667Ni20Cu13.3合金作为研究对象,制备了不同直径的棒状试样,考察了冷却速率对合金组织结构和力学性能的影响.结果表明,块体金属玻璃基体中原位析出塑性相-形状记忆合金过冷奥氏体相B2-TiNi,应力加载时能够发生马氏体相变对玻璃基体增强增韧.而在一定冷却速率下,塑性相和脆性金属间化合物相在非晶基体中同时析出,试样最终断裂方式取决于马氏体相和脆性相力学行为的竞争.

  1. Phosphate-based glass fiber vs. bulk glass: Change in fiber optical response to probe in vitro glass reactivity.

    Science.gov (United States)

    Massera, J; Ahmed, I; Petit, L; Aallos, V; Hupa, L

    2014-04-01

    This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca-P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca-P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca-P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca-P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ.

  2. Polymeric, Metallic, and Other Glasses in Introductory Chemistry

    Science.gov (United States)

    Hawkes, Stephen J.

    2008-01-01

    Non-ceramic glasses are not adequately discussed in introductory chemistry. Such glasses include polycarbonate, which many corrective lenses are made of, amber, enamel, gelatin, hard candy, coal, refrigerated glycerol, and metallic glasses that have been marketed in recent decades. What is usually discussed in elementary texts is siliceous glass,…

  3. Metallic glass nanostructures of tunable shape and composition.

    Science.gov (United States)

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-04-22

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties.

  4. The β relaxation in metallic glasses: an overview

    Directory of Open Access Journals (Sweden)

    Hai-Bin Yu

    2013-05-01

    Full Text Available Metallic glasses, combining metallic bonding and disordered atomic structures, are at the cutting edge of metallic materials research. Recent advances in this field have revealed that many key questions in glassy physics are inherently connected to one important relaxation mode: the so-called secondary (β relaxation. Here, in metallic glasses, we review the features of β relaxations and their relations to other processes and properties. Special emphasis is put on their current roles and future promise in understanding the glass transition phenomenon, mechanical properties and mechanisms of plastic deformation, diffusion, physical aging, as well as the stability and crystallization of metallic glasses.

  5. Tribological and mechanical properties of high power laser surface-treated metallic glasses

    NARCIS (Netherlands)

    Matthews, D. T. A.; Ocelik, V.; de Hosson, J. Th. M.

    2007-01-01

    The processing power of high power Nd:YAG laser has been utilised to achieve the inherently high cooling rates required to form many of today's bulk metallic glasses (BMGs). The production of thick (>= 250 mu m) amorphous surface layers has been considered. Microstructural and chemical observation t

  6. 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.

  7. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses.

    Science.gov (United States)

    Sedighi, Sina; Kirk, Donald Walter; Singh, Chandra Veer; Thorpe, Steven John

    2015-09-21

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal-transition metal and transition metal-metalloid (TM-M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM-M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator.

  8. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses

    Science.gov (United States)

    Sedighi, Sina; Kirk, Donald Walter; Singh, Chandra Veer; Thorpe, Steven John

    2015-09-01

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal-transition metal and transition metal-metalloid (TM-M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM-M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator.

  9. Phonon thermal transport in metallic glasses below 100 K

    Energy Technology Data Exchange (ETDEWEB)

    Matey, James Regis

    1978-01-01

    Measurements of the phonon thermal conductivity of a variety of metallic glasses were made. In each case, the temperature dependence and magnitude of the phonon thermal conductivity of the glassy metal was very similar to that characteristic of nonmetallic glasses. Variation of sound velocity measurements were made on a glassy palladium silicon alloy and a qualitative similarity was found between its behavior and the behavior of nonmetallic glasses. These findings and results from other laboratories have led to the conclusion that the localized excitations responsible for the anomalous behavior of nonmetallic glasses are also present in the metallic glasses.

  10. An Assessment of Binary Metallic Glasses: Correlations Between Structure, Glass Forming Ability and Stability (Preprint)

    Science.gov (United States)

    2011-07-01

    release; distribution unlimited. 1. Introduction It has long been suggested that metallic glass stability and glass-forming ability (GFA) are... magnetostriction of Co-Cr-Zr amorphous alloys’, Rapidly Quenched Metals, Proc. 4th International Conference on Rapidly Quenched Metals, Sendai, Japan, 861-864

  11. Thermodynamic model for glass forming ability of ternary metallic glass systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The thermodynamic model of multicomponent chemical short range order (MCSRO) was established in order to evaluate the glass forming ability (GFA) of ternary alloys. Comprehensive numerical calculations using MSCRO software were conducted to obtain the composition dependence of the MCSRO undercooling in Zr-Ni-Cu, Zr-Si-Cu and Pd-Si-Cu ternary systems. By the MCSRO undercooling principle, the composition range of Zr-Ni-Cu system with optimum GFA is determined to be 62.5~75Zr, 5~20Cu, 12.5~25Ni (n(Ni)/n(Cu)=1~5). The TTT curves of Zr-Ni-Cu system were also calculated based on the MCSRO model. The critical cooling rates for Zr-based alloy with deep MSCRO undercooling are estimated to be as low as 100?K/s, which is consistent with the practical cooling rate in the preparation of Zr-based bulk metallic glass (BMG). The calculation also illustrates that the easy glass forming systems such as Pd-based alloys exhibit an extraordinary deep MCSRO undercooling. It is shown that the thermodynamic model of MCSRO provides an effective method for the alloy designing of BMG.

  12. Feed Variability and Bulk Vitrification Glass Performance Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, Lenna A.; Vienna, John D.

    2005-01-10

    The supplemental treatment (ST) bulk vitrification process will obtain its feed, consisting of low-activity waste (LAW), from more than one source. One purpose of this letter report is to describe the compositional variability of the feed to ST. The other is to support the M-62-08 decision by providing a preliminary assessment of the effectiveness of bulk vitrification (BV), the process that has been selected to perform supplemental treatment, in handling the ST feed envelope. Roughly nine-tenths of the ST LAW feed will come from the Waste Treatment Plant (WTP) pretreatment. This processed waste is expected to combine (1) a portion of the same LAW feed sent to the WTP melters and (2) a dilute stream that is the product of the condensate from the submerged-bed scrubber (SBS) and the drainage from the electrostatic precipitator (WESP), both of which are part of the LAW off-gas system. The manner in which the off-gas-product stream is concentrated to reduce its volume, and the way in which the excess LAW and off-gas product streams are combined, are part of the interface between WTP and ST and have not been determined. This letter report considers only one possible arrangement, in which half of the total LAW is added to the off-gas product stream, giving an estimated ST feed stream from WTP. (Total LAW equals that portion of LAW sent to the WTP LAW vitrification plant (WTP LAW) plus the LAW not currently treatable in the LAW vitrification plant due to capacity limitations (excess)).

  13. Mid-infrared emission from Dy3+ doped tellurite bulk glass and waveguides

    Science.gov (United States)

    Richards, Billy D. O.; Teddy-Fernandez, Toney; Jha, Animesh; Binks, David

    2012-11-01

    We present the fabrication and characterisation of Dy3+-doped tellurite glasses and waveguides for applications in the mid-IR. The low phonon energy and large rare-earth ion solubility of tellurite glasses, as well as having infrared transmission ranges up to glasses, glass characterisation and rare-earth ion spectroscopy which is compared to other glass hosts relevant to the mid-IR such as fluoride glasses. When excited with an 808 nm laser diode source, Dy3+ doped tellurite bulk glasses exhibited very broad fluorescence from the 6H13/2 - 6H15/2 transition which extends from 3 μm to 3.6 μm FWHM compared to 2.9 μm to 3.1 μm in Dy3+ doped ZBLAN glass. This broad and red-shifted fluorescence band in tellurite glass may find use in LIDAR and sensing applications as it coincides with an atmospheric transmission band, compared to the ~3 μm emission of Dy3+ doped ZBLAN lasers which is absorbed by atmospheric water.

  14. Structural and magnetic properties of bulk nanocrystalline Erbium metal

    Directory of Open Access Journals (Sweden)

    Ming Yue

    2011-06-01

    Full Text Available Bulk nanocrystalline Erbium metals were prepared via Spark Plasma Sintering (SPS and subsequent annealing process. The nanocrystalline Er metals have the same hexagonal close packed structure as that of coarse-grained sample. Decrease in grain size results in remarkable changes in the three magnetic ordering temperatures of the nanocrystalline Er metal. At 5 K, the magnetization drops by 10.9%, while the coercivity increases by 4 times for nanocrystalline Er compared with those of coarse-grained sample. These results indicate the remarkable influence of the nanostructure on the magnetism of Er due to finite size effect.

  15. Nanoscale size effects in crystallization of metallic glass nanorods.

    Science.gov (United States)

    Sohn, Sungwoo; Jung, Yeonwoong; Xie, Yujun; Osuji, Chinedum; Schroers, Jan; Cha, Judy J

    2015-09-01

    Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding.

  16. Phase Separation and Microstructure Evolution of Zr48Cu36Ag8Al8 Bulk Metallic Glass in the Supercooled Liquid Region%过冷液态Zr48Cu36Ag8Al8块体非晶合金的相分离及组织演变

    Institute of Scientific and Technical Information of China (English)

    孙琳琳; 王军; 寇宏超; 李金山; 张平祥

    2016-01-01

    The effect of annealing temperature on the microstructure evolution of Zr48Cu36Ag8Al8 bulk metallic glass was investigated by X-ray diffraction (XRD),differential scanning calorimetry (DSC) and transmission electron microscopy (TEM).Results show that the as-cast Zr48Cu36Ag8Al8 alloy by rapid solidification exhibits a typical characteristic of an amorphous structure.After annealed at 703 K for 20 min,a homogeneous amorphous matrix is separated into two different glassy phases,namely,phase separation occurs.Because phase separation structure will compete with the amorphous matrix during isothermal annealing,this structure is easily decomposed and transformed into the crystalline phases AlZr2 and AlAg3 with annealing temperature increasing.The microstructure of Zr48Cu36Ag8Al8 bulk metallic glass undergoes the local structure transformation,phase separation and nano-crystallization transformation during heat treatment in the supercooled liquid region,which implies that the rnicrostructure of Zr48Cu36Ag8Al8 bulk metallic glass is sensitive to the annealing temperature.In addition,the formation of phase separation will accelerate the formation ofnano-crystals.%通过X射线衍射(XRD)、差示扫描量热法(DSC)和透射电子显微镜(TEM)研究了退火温度对Zr48Cu36Ag8Al8金属玻璃微观结构演化的影响.结果表明,快速凝固获得的样品为典型的非晶态结构.当样品在703 K保温20 rmin时,均一的非晶基体相分离成2种非晶合金,即,发生相分离.由于相分离结构与非晶基体在等温退火过程是竞争的关系,这个结构很容易向晶化态进行转变,形成AlZr2和AlAg3相.Zn8Cu36Ag8l8金属玻璃的微观结构在过冷液相区等温退火过程中经历了局部结构转变,相分离以及纳米晶转变,这个过程意味着Zr48Cu36Ag8Al8金属玻璃的微观结构对退火温度十分敏感.此外,相分离的形成可以加速纳米晶的形成.

  17. POLYMER CHAIN DIFFUSION AT A TEMPERATURE BELOW ITS BULK GLASS TRANSITION TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Tisato Kajiyama; Daisuke Kawaguchi; Keiji Tanaka

    2003-01-01

    In this study, it was examined whether the dynamics of polymer chains at a surface is different from that in the bulk, and if so, to what extent they differ in terms of surface glass transition temperature and diffusion coefficient. Obtained results clearly indicate that surface chains can travel for a relatively large distance in comparison with the characteristic length scale of usual segmental motion even at a temperature below its bulk glass transition temperature, Tbg. This is consistent with our previous results that the surface glass transition temperature is much lower than the corresponding Tbg.Also, it was experimentally revealed that there was a gradient of molecular motion in the surface region.

  18. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, Sina; Kirk, Donald Walter; Singh, Chandra Veer, E-mail: chandraveer.singh@utoronto.ca; Thorpe, Steven John [Department of Materials Science and Engineering, University of Toronto, Room 140, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2015-09-21

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal–transition metal and transition metal–metalloid (TM–M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM–M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator.

  19. Application of the model of delocalized atoms to metallic glasses

    Science.gov (United States)

    Sanditov, D. S.; Darmaev, M. V.; Sanditov, B. D.

    2017-01-01

    The parameters of the model of delocalized atoms applied to metallic glasses have been calculated using the data on empirical constants of the Vogel-Fulcher-Tammann equation (for the temperature dependence of viscosity). It has been shown that these materials obey the same glass-formation criterion as amorphous organic polymers and inorganic glasses. This fact qualitatively confirms the universality of the main regularities of the liquid-glass transition process for all amorphous materials regardless of their origin. The energy of the delocalization of an atom in metallic glasses, Δɛ e ≈ 20-25 kJ/mol, coincides with the results obtained for oxide inorganic glasses. It is substantially lower than the activation energies for a viscous flow and for ion diffusion. The delocalization of an atom (its displacement from the equilibrium position) for amorphous metallic alloys is a low-energy small-scale process similar to that for other glass-like systems.

  20. Nanowear of a Zr Based Bulk Metallic Glass/Nanocrystalline Alloy

    Institute of Scientific and Technical Information of China (English)

    LIANGSong; HEJian-ying; CHUWu-yang; LIJin-xu; SUNDong-bai; QIAOLi-jie

    2004-01-01

    The hardness, elastic modulus, nano-scratch resistance and wear depth for a bulk metallic glass of Zr57NbsCu15.4 Ni12.6Al10 and its partial crystallization alloys have been measured by using nanoindentation method. The results showed that partial crystallization did not influence the reduced elastic modulus but increased the hardness, and then increased the scratch coefficient. The scratch coefficient increased linearly with increasing the hardness H but decreases when H>6.2GPa. Partial crystallization decreased evidently the wear depth, and when the load was large the wear depth decreased with increasing the hardness.

  1. Superconducting state parameters of ternary metallic glasses

    Indian Academy of Sciences (India)

    Aditya M Vora

    2011-12-01

    The well-known empty core (EMC) model potential of Ashcroft was used to study the theoretical investigation of the superconducting state parameters (SSP) viz. electron–phonon coupling strength , Coulomb pseudopotential $\\mu^{\\ast}$, transition temperature $T_{C}$, isotope effect exponent and effective interaction strength $N_{O}V$ of some ternary metallic glasses. Most recent local field correction function due to Sarkar et al is used to study the screening influence on the aforesaid properties. Quadratic $T_{C}$ equations have been proposed and found successful. Also, the present findings are found to be in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the ternary superconductors. The pseudo-alloy-atom (PAA) model was applied for the first time instead of Vegard’s law.

  2. The Metal-Hydrogen System Basic Bulk Properties

    CERN Document Server

    Fukai, Yuh

    2005-01-01

    Metal hydrides are of inestimable importance for the future of hydrogen energy. This unique monograph presents a clear and comprehensive description of the bulk properties of the metal-hydrogen system. The statistical thermodynamics is treated over a very wide range of pressure, temperature and composition. Another prominent feature of the book is its elucidation of the quantum mechanical behavior of interstitial hydrogen atoms, including their states and motion. The important topic of hydrogen interaction with lattice defects and its materials-science implications are also discussed thoroughly. This second edition has been substantially revised and updated.

  3. Specific Heat in a Typical Metallic Glass Former

    Institute of Scientific and Technical Information of China (English)

    KE Hai-Bo; ZHAO Zuo-Feng; WEN Ping; WANG Wei-Hua

    2012-01-01

    The specific heat in a typical Pd40Ni10Cu30P20 metallic glass forming system is investigated.It is found that the specific heat of the metallic liquid is around 4.7R (R is the gas constant) and that it is almost independent of temperature.The glass transition observed during cooling is accompanied by a decrease in the specific heat of 1.5R.The specific heat of the metallic glass is similar to that of its crystalline phases,contributed mainly from atomic vibrations.Combined with the results of the structural relaxation and diffusivities,we demonstrate an intrinsic connection between the atomic motion and the specific heat in the metallic glass-forming liquid.The results support the idea that glass transition is a process accompanied by the freezing of most of the atomic transitional motions in a metallic supercooled liquid during cooling.%The specific heat in a typical Pd40 Ni10 Cu30 P20 metallic glass forming system is investigated. It is found that the specific heat of the metallic liquid is around 4.7R (R is the gas constant) and that it is almost independent of temperature. The glass transition observed during cooling is accompanied by a decrease in the specific heat of 1.5R. The specific heat of the metallic glass is similar to that of its crystalline phases, contributed mainly from atomic vibrations. Combined with the results of the structural relaxation and diffusivities, we demonstrate an intrinsic connection between the atomic motion and the specific heat in the metallic glass-forming liquid. The results support the idea that glass transition is a process accompanied by the freezing of most of the atomic transitional motions in a metallic supercooled liquid during cooling.

  4. A fractal interpretation of size effects on the strength of metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yun [Dipartimento Scienza Applicata e Tecnologia, Politecnico di Torino, Torino, 10129 (Italy); Gong, Baoming, E-mail: gong_bm@tju.edu.cn [Department of Material Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin, 300072 (China); Deng, Caiyan [Department of Material Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin, 300072 (China)

    2013-11-29

    Yielding strength of metallic glasses in the uniaxial tensile and compressive tests is scale-dependent, which is attributed to the self-similar distribution of atomic cluster and free volume in the work. In contrast with the Weibull statistical theory previously employed in scaling phenomena of metallic glasses, fractal scaling laws are for the first time applied to describe the size effect inherent to the material disorder. Especially, the Multifractal Scaling Law (MFSL) originally proposed for quasi-brittle materials is used to interpret some experimental data in the literature. The best-fitted parameters (f{sub y} and l{sub ch}) from the MFSL are in good consistency with the bulk yielding strength and the shear band size of metallic glasses observed in the alternative approaches or experiments. The fractal size effect laws provide insight into not only the scaling phenomena, but also further engineering strength predictions and designs.

  5. The glass-forming ability of model metal-metalloid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-03-14

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σ{sub S}/σ{sub L} and number fraction x{sub S} of the metalloid species. We show that the regime in the space of σ{sub S}/σ{sub L} and x{sub S} where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  6. The glass-forming ability of model metal-metalloid alloys

    Science.gov (United States)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

    2015-03-01

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σS/σL and number fraction xS of the metalloid species. We show that the regime in the space of σS/σL and xS where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  7. Evolution of Shear Bands of Tungsten Fiber Reinforced Zr-Based Bulk Metallic Glass Matrix Composite in Deformation Process%连续钨丝增强锆基块体金属玻璃变形过程中剪切带的演化

    Institute of Scientific and Technical Information of China (English)

    姜斐; 刘子毅; 陈光

    2011-01-01

    研究体积分数为60%的连续钨丝/Zr41.2 Ti13.8 Cu12.5Ni10Be22.5块体金属玻璃复合材料准静态压缩变形过程中剪切带的演化过程.发现在弹性变形段不形成剪切带,剪切带是在塑性变形过程中产生并发展的,且剪切带的数量随着变形量的增加而增大,间距随着变形量的增加而减小;当间距减小到一定值时产生剪切裂纹并不断扩展,最终导致断裂破坏.%Evolution process of shear bands of tungsten fiber reinforced Zr-based bulk metallic glass matrix composite in deformation process was investigated. It is found that no shear band forms in the elastic stage, the shear band forms and develops in the plastic deformation process. Moreover, the number of shear bands increases with the increase of the deformation quantum, and the shear band spacing decreases with the increase of the deformation quantum. When the shear band spacing reaches the critical value? Shear cracks occur and continuously extend, finally resulting in the fracture failure.

  8. Approaching the ideal elastic limit of metallic glasses

    OpenAIRE

    Tian, Lin; Cheng, Yong-Qiang; Shan, Zhi-Wei; Li, Ju; Cheng-cai WANG; Han, Xiao-dong; Sun, Jun; Ma, Evan

    2012-01-01

    The ideal elastic limit is the upper bound to the stress and elastic strain a material can withstand. This intrinsic property has been widely studied for crystalline metals, both theoretically and experimentally. For metallic glasses, however, the ideal elastic limit remains poorly characterized and understood. Here we show that the elastic strain limit and the corresponding strength of submicron-sized metallic glass specimens are about twice as high as the already impressive elastic limit ob...

  9. Formation of monatomic metallic glasses through ultrafast liquid quenching.

    Science.gov (United States)

    Zhong, Li; Wang, Jiangwei; Sheng, Hongwei; Zhang, Ze; Mao, Scott X

    2014-08-14

    It has long been conjectured that any metallic liquid can be vitrified into a glassy state provided that the cooling rate is sufficiently high. Experimentally, however, vitrification of single-element metallic liquids is notoriously difficult. True laboratory demonstration of the formation of monatomic metallic glass has been lacking. Here we report an experimental approach to the vitrification of monatomic metallic liquids by achieving an unprecedentedly high liquid-quenching rate of 10(14) K s(-1). Under such a high cooling rate, melts of pure refractory body-centred cubic (bcc) metals, such as liquid tantalum and vanadium, are successfully vitrified to form metallic glasses suitable for property interrogations. Combining in situ transmission electron microscopy observation and atoms-to-continuum modelling, we investigated the formation condition and thermal stability of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses. Our technique also shows great control over the reversible vitrification-crystallization processes, suggesting its potential in micro-electromechanical applications. The ultrahigh cooling rate, approaching the highest liquid-quenching rate attainable in the experiment, makes it possible to explore the fast kinetics and structural behaviour of supercooled metallic liquids within the nanosecond to picosecond regimes.

  10. Bleaching versus poling: Comparison of electric field induced phenomena in glasses and glass-metal nanocomposites

    Science.gov (United States)

    Lipovskii, A. A.; Melehin, V. G.; Petrov, M. I.; Svirko, Yu. P.; Zhurikhina, V. V.

    2011-01-01

    By examining the electric field induced processes in glasses and glass-metal nanocomposites (GMN) we propose mechanism of the electric field assisted dissolution (EFAD) of metal nanoparticles in glass. We show that in both glass poling and EFAD processes, the strong (up to 1 V/nm) local electric field in the subanodic region is due to the presence of "slow" hydrogen ions bonded to nonbridging oxygen atoms in glass matrix. However, the origin of these hydrogen ions in glass and GMN is different. Specifically, when we apply the electric field to a virgin glass, the enrichment of the glass with hydrogen species takes place in the course of the poling. In GMN, the hydrogen ions have been incorporated into the glass matrix during metal nanoparticles formation via reduction in a metal by hydrogen, i.e., before the electric field was applied. The EFAD of metal nanoparticles resembles the electric field stimulated diffusion of metal film in glass (the important difference however is that in GMN, there is no direct contact of dissolving metal entity with anodic electrode). This similarity makes it possible to estimate the energy of thermal activated transition of silver atoms from a nanoparticle to glass matrix as ˜1.3 eV. Electroneutrality of the GMN requires emission of electrons from nanoparticles. Photoconductivity spectra of soda-lime glasses and the results of numerical calculations of band structure of fused silica, sodium disilicate and sodium-calcium-silicate glass enable us to evaluate the bandgap and the position of electron mobility edge in soda-lime glass. The evaluated values are ˜6 eV and ˜1.2 eV below vacuum level, respectively. The bent of the glass band structure in strong electric field permits a direct tunneling of Fermi electrons from silver nanoparticle (4.6 eV below the vacuum level) to the glass conductivity band. Evaluated in accordance with the Fowler-Nordheim equation the magnitude of electric field necessary to establish comparable electron

  11. Mare glasses from Apollo 17 - Constraints on the moon's bulk composition

    Science.gov (United States)

    Delano, J. W.; Lindsley, D. H.

    1983-01-01

    Two previously unreported varieties of mare volcanic glass have been discovered in Apollo 17 samples. Twenty-three chemical types of volcanic glass have now been analyzed from the six Apollo landing sites. These volcanic glasses, which may be samples of primary magmas derived from the differentiated lunar mantle, define two linear arrays that seem to reflect regional, if not global, regularities among the source regions of these melts. Additional systematics among these glasses have been used to estimate the bulk composition of the moon. The results suggest that the refractory lithophile elements are present at abundances of 1.7 x chondrites. The silicate portion of the moon appears to have a major-element composition similar to a volatile (Si, Na, K)-depleted, earth's upper mantle. The theory involving an earth-fission origin of the moon can be tested further through trace element analyses on the volcanic glasses, and through determination of the N/Ar-36 ratio and noble gas isotopes from primordial lunar gas trapped within vesicles associated with mare volcanic glass.

  12. Clustered field evaporation of metallic glasses in atom probe tomography.

    Science.gov (United States)

    Zemp, J; Gerstl, S S A; Löffler, J F; Schönfeld, B

    2016-03-01

    Field evaporation of metallic glasses is a stochastic process combined with spatially and temporally correlated events, which are referred to as clustered evaporation (CE). This phenomenon is investigated by studying the distance between consecutive detector hits. CE is found to be a strongly localized phenomenon (up to 3nm in range) which also depends on the type of evaporating ions. While a similar effect in crystals is attributed to the evaporation of crystalline layers, CE of metallic glasses presumably has a different - as yet unknown - physical origin. The present work provides new perspectives on quantification methods for atom probe tomography of metallic glasses.

  13. Ductility and work hardening in nano-sized metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D. Z., E-mail: dzchen@caltech.edu [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Gu, X. W. [Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); An, Q.; Goddard, W. A. [Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States); Greer, J. R. [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); The Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-02-09

    In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work hardening, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses.

  14. The shells of atomic structure in metallic glasses

    Science.gov (United States)

    Pan, S. P.; Feng, S. D.; Qiao, J. W.; Dong, B. S.; Qin, J. Y.

    2016-02-01

    We proposed a scheme to describe the spatial correlation between two atoms in metallic glasses. Pair distribution function in a model iron was fully decomposed into several shells and can be presented as the spread of nearest neighbor correlation via distance. Moreover, angle distribution function can also be decomposed into groups. We demonstrate that there is close correlation between pair distribution function and angle distribution function for metallic glasses. We think that our results are very helpful understanding the atomic structure of metallic glasses.

  15. Molecular dynamics study of the ternary Cu50Ti25Zr25 bulk glass forming alloy

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available The structure and thermodynamic properties of a ternary Cu50Ti25Zr25 metallic glass forming alloy in solid-liquid to glass phases were studied using molecular dynamics (MD method based on tight-binding (TB potentials. An atomic description of the melting, glass formation and crystallization process has been analyzed using different heating and cooling rates. The computed Glass Forming Ability (GFA parameters are in good agreement with experimental data. The structure analysis of the Cu50Ti25Zr25 based on molecular dynamics simulation will be also presented and compared with available MD results. We have also discussed the crystallization transition with two different interatomic potentials used in this work

  16. Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

    Institute of Scientific and Technical Information of China (English)

    BAI Xue; WANG TongLe; CUI YuanYuan; DING Ning; LI JiaHao; LIU BaiXin

    2012-01-01

    Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium.It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around Cu17Mo20Hf63 and Cu34Mo57Hf9,respectively.Interestingly,at the nearly equal-atomic stoichiometry of Cu38Mo31Hf31,a dual-phase Cu-Mo-Hf metallic glass,consisting both of the Mo-Hf-based and Cu-Mo-based phases,was first obtained at relatively low irradiation doses ranging from (1-5)×1015 Xe+/cm2,and a single-phase metallic glass was eventually obtained at a dose of 7×1015 Xe+/cm2.In addition,two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9,and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses,dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions,respectively.The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.

  17. Ultra-short pulsed laser engineered metal-glass nanocomposites

    CERN Document Server

    Stalmashonak, Andrei; Abdolvand, Amin

    2013-01-01

    Glasses containing metallic nanoparticles exhibit very promising linear and nonlinear optical properties, mainly due to the surface plasmon resonances (SPRs) of the nanoparticles. The spectral position in the visible and near-infrared range and polarization dependence of the SPR are characteristically determined by the nanoparticles’ shapes. The focus of Ultra-Short Pulsed Laser Engineered Metal-Glass Nanocomposites is the interaction of intense ultra-short laser pulses with glass containing silver nanoparticles embedded in soda-lime glass, and nanostructural modifications in metal-glass nanocomposites induced by such laser pulses. In order to provide a comprehensive physical picture of the processes leading to laser-induced persistent shape transformation of the nanoparticles, series of experimental results investigating the dependences of laser assisted shape modifications of nanoparticles with laser pulse intensity, excitation wavelength, temperature are considered. In addition, the resulting local opti...

  18. Sheet-bulk metal forming – forming of functional components from sheet metals

    Directory of Open Access Journals (Sweden)

    Merklein Marion

    2015-01-01

    Full Text Available The paper gives an overview on the application of sheet-bulk metal forming operations in both scientific and industrial environment. Beginning with the need for an innovative forming technology, the definition of this new process class is introduced. The rising challenges of the application of bulk metal forming operations on sheet metals are presented and the demand on a holistic investigation of this topic is motivated. With the help of examples from established production processes, the latest state of technology and the lack on fundamental knowledge is shown. Furthermore, perspectives regarding new research topics within sheet-bulk metal forming are presented. These focus on processing strategies to improve the quality of functional components by the application of process-adapted semi-finished products as well as the local adaption of the tribological system.

  19. Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge.

    Science.gov (United States)

    Kaltenboeck, Georg; Harris, Thomas; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P; Demetriou, Marios D; Johnson, William L

    2014-10-01

    The ability of the rapid-capacitive discharge approach to access optimal viscosity ranges in metallic glasses for thermoplastic processing is explored. Using high-speed thermal imaging, the heating uniformity and stability against crystallization of Zr35Ti30Cu7.5Be27.5 metallic glass heated deeply into the supercooled region is investigated. The method enables homogeneous volumetric heating of bulk samples throughout the entire supercooled liquid region at high rates (~10(5) K/s) sufficient to bypass crystallization throughout. The crystallization onsets at temperatures in the vicinity of the "crystallization nose" were identified and a Time-Temperature-Transformation diagram is constructed, revealing a "critical heating rate" for the metallic glass of ~1000 K/s. Thermoplastic process windows in the optimal viscosity range of 10(0)-10(4) Pa · s are identified, being confined between the glass relaxation and the eutectic crystallization transition. Within this process window, near-net forging of a fine precision metallic glass part is demonstrated.

  20. Universal slip dynamics in metallic glasses and granular matter – linking frictional weakening with inertial effects

    Science.gov (United States)

    Denisov, Dmitry V.; Lőrincz, Kinga A.; Wright, Wendelin J.; Hufnagel, Todd C.; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T.; Dahmen, Karin A.; Schall, Peter

    2017-03-01

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics.

  1. Localized crystallization in shear bands of a metallic glass

    Science.gov (United States)

    Yan, Zhijie; Song, Kaikai; Hu, Yong; Dai, Fuping; Chu, Zhibing; Eckert, Jürgen

    2016-01-01

    Stress-induced viscous flow is the characteristic of atomic movements during plastic deformation of metallic glasses in the absence of substantial temperature increase, which suggests that stress state plays an important role in mechanically induced crystallization in a metallic glass. However, it is poorly understood. Here, we report on the stress-induced localized crystallization in individual shear bands of Zr60Al15Ni25 metallic glass subjected to cold rolling. We find that crystallization in individual shear bands preferentially occurs in the regions neighboring the amorphous matrix, where the materials are subjected to compressive stresses demonstrated by our finite element simulations. Our results provide direct evidence that the mechanically induced crystallization kinetics is closely related with the stress state. The crystallization kinetics under compressive and tensile stresses are interpreted within the frameworks of potential energy landscape and classical nucleation theory, which reduces the role of stress state in mechanically induced crystallization in a metallic glass.

  2. Phenomenological theory of bulk diffusion in metal oxides

    Science.gov (United States)

    Chuvil'deev, V. N.; Smirnova, E. S.

    2016-07-01

    Phenomenological description of bulk diffusion in oxide ceramics has been proposed. Variants of vacancy and vacancy-free diffusion models have been considered. In the vacancy models, ion migration is described as a fluctuation with the formation of a "liquid corridor," along which the diffusion ion transport in a "melt" is performed, or, as a fluctuation with the formation of an "empty corridor," in which the ion motion proceeds without activation. The vacancy-free model considers a fluctuation with the formation of a spherical liquid region whose sizes correspond to the first coordination sphere. It has been shown that both the vacancy models work in cubic metal oxides and the vacancy-free model is effective for describing diffusion in oxides having a noncubic structure. Detailed comparison of the models developed has been performed. It has been shown that the values of the activation energies for diffusion of metal and oxygen ions agree with the published data on bulk diffusion in stoichiometric oxide ceramics.

  3. Ultrasonic velocity and elastic moduli of heavy metal tellurite glasses

    Energy Technology Data Exchange (ETDEWEB)

    Afifi, Hesham; Marzouk, Samier

    2003-05-26

    Longitudinal and transverse ultrasonic waves velocities in lead tungsten tellurite glasses have been measured using the pulse-echo method at 5 MHz frequency and at room temperature (300 K). The elastic properties; longitudinal modulus, shear modulus, Young's modulus, bulk modulus and Poisson's ratio together with the microhardness, softening temperature, and Debye temperature are found to be rather sensitive to the glass composition. Information about the structure of the glass can be deduced after calculating the average stretching force constant and the average ring size. A comparison between the experimental elastic moduli data obtained in this study and those calculated theoretically by other models has been discussed.

  4. Fast Surface Dynamics of Metallic Glass Enable Superlatticelike Nanostructure Growth

    Science.gov (United States)

    Chen, L.; Cao, C. R.; Shi, J. A.; Lu, Z.; Sun, Y. T.; Luo, P.; Gu, L.; Bai, H. Y.; Pan, M. X.; Wang, W. H.

    2017-01-01

    Contrary to the formation of complicated polycrystals induced by general crystallization, a modulated superlatticelike nanostructure, which grows layer by layer from the surface to the interior of a Pd40Ni10Cu30P20 metallic glass, is observed via isothermal annealing below the glass transition temperature. The generation of the modulated nanostructure can be solely controlled by the annealing temperature, and it can be understood based on the fast dynamic and liquidlike behavior of the glass surface. The observations have implications for understanding the glassy surface dynamics and pave a way for the controllable fabrication of a unique and sophisticated nanostructure on a glass surface to realize the properties' modification.

  5. Bulk metallic glass for low noise fluxgate Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The team of Prime Photonics, Virginia Tech, and Utron Kinetics propose to develop a fabrication technology that will result in drop-in replacements for a diminishing...

  6. Scattering mechanical performances for brittle bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    J. W. Qiao

    2014-11-01

    Full Text Available Scattering mechanical performances of brittle La- and Mg-based BMGs are found in the present study. Upon dynamic loading, there exist largely scattered fracture strengths even if the strain rates are under the same order, and the BMG systems are the same. The negative strain rate dependence for La- and Mg-based BMGs is obtained, i.e., a decreased fracture strength is dominating from quasi-static to dynamic compression. At cryogenic temperatures, distinguishingly low fracture strengths are available for these two brittle BMGs, and decreased tolerance to accommodate strains makes BMGs more and more brittle. It is concluded that the scattering mechanical performances of brittle BMGs should be carefully evaluated before actual applications.

  7. Free standing bulk metallic glass microcomponents: Tooling considerations

    DEFF Research Database (Denmark)

    Byrne, Cormac; Eldrup, Morten Mostgaard; Ohnuma, Masato

    2010-01-01

    and mechanical locking. Several solutions to this extraction problem were explored, including high temperature extraction, lubrication and the use of materials with low coefficients of thermal expansion (CTE) as die/mold materials. We show that the use of appropriately chosen low CTE die materials offers...

  8. Atmospherically deposited trace metals from bulk mineral concentrate port operations

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Mark Patrick, E-mail: mark.taylor@mq.edu.au

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m{sup 2}/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m{sup 2}/day). Maximum loading values after a 10-minute play period were 3012 μg/m{sup 2}, more than seven times the goal of 400 μg/m{sup 2} used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m{sup 2}) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m{sup 2}/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ({sup 208}Pb/{sup 207}Pb and {sup 206}Pb/{sup 207}Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear — even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection. - Graphical abstract: Post-play hand wipe, Headland Park, Townsville, Australia. - Highlights: • Bulk mineral port

  9. Corrosion by a Heavy Metal Oxide Glass

    Institute of Scientific and Technical Information of China (English)

    B.B.Rana

    2005-01-01

    Melts of lead bismuth gallate compositions are highly corrosive and attack on crucibles of different materials. In the present study, corrosion by a base glass (50PbO-30Bi2O3-20Ga2O3 in mole fraction) melted using different crucibles and the effect onUV-VIS and IR edges were studied. By melting the base glass in platinum/2% rhodium, gold zirconia and alumina crucibles showed less effect on the IR edge and therefore shifted the infrared edge to longer wavelength, whereas silica crucible contaminated the glass, causing a severe deterioration in the infrared and hence shifted infrared edge to much shorter wavelength. In the UV-VIS region, base glass melted in platinum/2% rhodium crucible shifted the edge to the longest wavelength whereas silica crucible shifted the edge to shorter wavelength.The contaminants from gold, zirconia and alumina crucibles caused the UV-VIS edge of the base glass to lie between the two extremes of Pt/2% Rh and SiO2 crucibles. The glasses melted in above mentioned crucibles were also characterized with inductively coupled plasma spectroscopy (ICP) analysis to measure the level of contamination from the crucibles. Depending upon crucible used, the colors of glasses obtained ranged from red to yellow.

  10. Femtosecond laser writing of Bragg grating waveguide bundles in bulk glass.

    Science.gov (United States)

    Thiel, Markus; Flachenecker, Günter; Schade, Wolfgang

    2015-04-01

    Waveguide bundles in bulk glass materials, consisting of several parallel scans of refractive index modifications, have been generated with a low-repetition femtosecond laser. Additionally, Bragg grating (BG) structures for 840 and 1550 nm have been introduced by segmentation of the central scan. A spectral loss in the transmission signal of >36  dB was achieved at 1550 nm with a second-order Bragg grating waveguide (BGW) in fused silica, which corresponds to an intrinsic grating efficiency of >16  dB/cm. This is to our knowledge the strongest BG structure realized in glass with a femtosecond laser. The BGW were proven to be stable up to a temperature of 250°C in fused silica. The diameter of the waveguide bundles can be adapted very easily for a broad range of wavelengths and have been demonstrated for diameters between 1 and 50 μm. The transmission properties of the waveguide bundles are affected minorly by the insertion of BG structures, which opens the ability for adjusting the BGW for a broad range of wavelength in single-mode or multimode optical circuits. BGW have been realized successfully in fused silica, borosilicate glass (BOROFLOAT 33), and AF 32 eco Thin Glass from Schott.

  11. Elastic properties of Pd40Cu30Ni10P20 bulk glass in supercooled liquid region

    DEFF Research Database (Denmark)

    Nishiyama, N.; Inoue, A.; Jiang, Jianzhong

    2001-01-01

    In situ ultrasonic measurements for the Pd40Cu30Ni10P20 bulk glass in three states: Glassy solid, supercooled liquid, and crystalline, have been performed. It is found that velocities of both longitudinal and transverse waves and elastic moduli (shear modulus, bulk modulus, Young's modulus, and L...

  12. The Critical Criterion on Runaway Shear Banding in Metallic Glasses

    Science.gov (United States)

    Sun, B. A.; Yang, Y.; Wang, W. H.; Liu, C. T.

    2016-02-01

    The plastic flow of metallic glasses (MGs) in bulk is mediated by nanoscale shear bands, which is known to proceed in a stick-slip manner until reaching a transition state causing catastrophic failures. Such a slip-to-failure transition controls the plasticity of MGs and resembles many important phenomena in natural science and engineering, such as friction, lubrication and earthquake, therefore has attracted tremendous research interest over past decades. However, despite the fundamental and practical importance, the physical origin of this slip-to-failure transition is still poorly understood. By tracking the behavior of a single shear band, here we discover that the final fracture of various MGs during compression is triggered as the velocity of the dominant shear band rises to a critical value, the magnitude of which is independent of alloy composition, sample size, strain rate and testing frame stiffness. The critical shear band velocity is rationalized with the continuum theory of liquid instability, physically originating from a shear-induced cavitation process inside the shear band. Our current finding sheds a quantitative insight into deformation and fracture in disordered solids and, more importantly, is useful to the design of plastic/tough MG-based materials and structures.

  13. Microscopic insight into the origin of enhanced glass-forming ability of metallic melts on micro-alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. J.; Chathoth, S. M., E-mail: smavilac@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong (China); Podlesnyak, A. [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Mamontov, E. [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wang, W. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2015-09-28

    Extensive efforts have been made to develop metallic-glasses with large casting diameter. Such efforts were hindered by the poor understanding of glass formation mechanisms and the origin of the glass-forming ability (GFA) in metallic glass-forming systems. In this work, we have investigated relaxation dynamics of a model bulk glass-forming alloy system that shows the enhanced at first and then diminished GFA on increasing the percentage of micro-alloying. The micro-alloying did not have any significant impact on the thermodynamic properties. The GFA increasing on micro-alloying in this system cannot be explained by the present theoretical knowledge. Our results indicate that atomic caging is the primary factor that influences the GFA. The composition dependence of the atomic caging time or residence time is found to be well correlated with GFA of the system.

  14. Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

    Institute of Scientific and Technical Information of China (English)

    ZHUO Long-Chao; PANG Shu-Jie; WANG Hui; ZHANG Tao

    2009-01-01

    Based on a new approach for designing glassy alloy compositions,bulk Al-based alloys with good glass-forming ability (GFA) are synthesized.The cast Al86Si0.5Ni4.06Co2.94 Y6Sc0.5 rod with a diameter of 1 mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod.The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 Gpa and maximum strength of 1.27 Gpa as well as an obvious plastic strain of about 2.4% during compressive deformation.This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability.

  15. Broadband directional couplers fabricated in bulk glass with high repetition rate femtosecond laser pulses.

    Science.gov (United States)

    Chen, Wei-Jen; Eaton, Shane M; Zhang, Haibin; Herman, Peter R

    2008-07-21

    A femtosecond fiber laser was applied to fabricate broadband directional couplers inside bulk glass for general power splitting application in the 1250 to 1650-nm wavelength telecom spectrum. The broadband response was optimized over the 400-nm bandwidth by tailoring the coupling strength and the waveguide interaction length to balance the differing wavelength dependence of the straight interaction and bent transition regions. High spatial finesse of the femtosecond-laser writing technique enabled close placement (approxiamtely 6 microm) of adjacent waveguides that underpinned the wavelength-flattened broadband response at any coupling ratio in the 0% to 100% range. The spectral responses were well-represented by coupled mode theory, permitting simple design and implementation of broadband couplers for bulk 3D optical circuit integration.

  16. Crystallization of heavy metal fluoride glasses

    Science.gov (United States)

    Bansal, Narottam P.; Bruce, Allan J.; Doremus, R. H.; Moynihan, C. T.

    1984-01-01

    The kinetics of crystallization of a number of fluorozirconate glasses were studied using isothermal and dynamic differential scanning calorimetry and X-ray diffraction. The addition of the fluorides LiF, NaF, AlF3, LaF3 to a base glass composition of ZrF4-BaF2 reduced the tendency to crystallize, probably by modifying the viscosity-temperature relation. ZrF4-BaF2-LaF3-AlF3-NaF glass was the most stable against devitrification and perhaps is the best composition for optical fibers with low scattering loss. Some glasses first crystallize out into metastable beta-BaZr2F10 and beta-BaZrF6 phases, which transform into the most stable alpha-phases when heated to higher temperatures. The size of the crystallites was estimated to be about 600 A from X-ray diffraction.

  17. In Situ Formation of Carbon Nanomaterials on Bulk Metallic Materials

    Directory of Open Access Journals (Sweden)

    J. Y. Xu

    2014-01-01

    Full Text Available Carbon nanomaterials were synthesized in situ on bulk 316L stainless steel, pure cobalt, and pure nickel by hybrid surface mechanical attrition treatment (SMAT. The microstructures of the treated samples and the resulted carbon nanomaterials were investigated by SEM and TEM characterizations. Different substrates resulted in different morphologies of products. The diameter of carbon nanomaterials is related to the size of the nanograins on the surface layer of substrates. The possible growth mechanism was discussed. Effects of the main parameters of the synthesis, including the carbon source and gas reactant composition, hydrogen, and the reaction temperature, were studied. Using hybrid SMAT is proved to be an effective way to synthesize carbon nanomaterials in situ on surfaces of metallic materials.

  18. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    Science.gov (United States)

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection.

  19. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dapeng [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  20. Effects of Mo additions on the glass-forming ability and magnetic properties of bulk amorphous Fe-C-Si-B-P-Mo alloys

    Institute of Scientific and Technical Information of China (English)

    YI; Seonghoon

    2010-01-01

    Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635–3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10–1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.

  1. Prediction of pressure-promoted thermal rejuvenation in metallic glasses

    Science.gov (United States)

    Miyazaki, Narumasa; Wakeda, Masato; Wang, Yun-Jiang; Ogata, Shigenobu

    2016-06-01

    Rejuvenation is the structural excitation of glassy materials, and is a promising approach for improving the macroscopic deformability of metallic glasses. This atomistic study proposes the application of compressive hydrostatic pressure during the glass-forming quenching process and demonstrates highly rejuvenated glass states that have not been attainable without the application of pressure. Surprisingly, the pressure-promoted rejuvenation process increases the characteristic short- and medium-range order, even though it leads to a higher-energy glassy state. This 'local order'-'energy' relation is completely opposite to conventional thinking regarding the relation, suggesting the presence of a well-ordered high-pressure glass/high-energy glass phase. We also demonstrate that the rejuvenated glass made by the pressure-promoted rejuvenation exhibits greater plastic performance than as-quenched glass, and greater strength and stiffness than glass made without the application of pressure. It is thus possible to tune the mechanical properties of glass using the pressure-promoted rejuvenation technique.

  2. Rejuvenation of metallic glasses by non-affine thermal strain.

    Science.gov (United States)

    Ketov, S V; Sun, Y H; Nachum, S; Lu, Z; Checchi, A; Beraldin, A R; Bai, H Y; Wang, W H; Louzguine-Luzgin, D V; Carpenter, M A; Greer, A L

    2015-08-13

    When a spatially uniform temperature change is imposed on a solid with more than one phase, or on a polycrystal of a single, non-cubic phase (showing anisotropic expansion-contraction), the resulting thermal strain is inhomogeneous (non-affine). Thermal cycling induces internal stresses, leading to structural and property changes that are usually deleterious. Glasses are the solids that form on cooling a liquid if crystallization is avoided--they might be considered the ultimate, uniform solids, without the microstructural features and defects associated with polycrystals. Here we explore the effects of cryogenic thermal cycling on glasses, specifically metallic glasses. We show that, contrary to the null effect expected from uniformity, thermal cycling induces rejuvenation, reaching less relaxed states of higher energy. We interpret these findings in the context that the dynamics in liquids become heterogeneous on cooling towards the glass transition, and that there may be consequent heterogeneities in the resulting glasses. For example, the vibrational dynamics of glassy silica at long wavelengths are those of an elastic continuum, but at wavelengths less than approximately three nanometres the vibrational dynamics are similar to those of a polycrystal with anisotropic grains. Thermal cycling of metallic glasses is easily applied, and gives improvements in compressive plasticity. The fact that such effects can be achieved is attributed to intrinsic non-uniformity of the glass structure, giving a non-uniform coefficient of thermal expansion. While metallic glasses may be particularly suitable for thermal cycling, the non-affine nature of strains in glasses in general deserves further study, whether they are induced by applied stresses or by temperature change.

  3. Simulation of Cu-Mg metallic glass: Thermodynamics and structure

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2004-01-01

    We have obtained effective medium theory interatomic potential parameters suitable for studying Cu-Mg metallic glasses. We present thermodynamic and structural results from simulations of such glasses over a range of compositions. We have produced low-temperature configurations by cooling from...... the melt at as slow a rate as practical, using constant temperature and pressure molecular dynamics. During the cooling process we have carried out thermodynamic analyses based on the temperature dependence of the enthalpy and its derivative, the specific heat, from which the glass transition temperature...

  4. Ordering and dimensional crossovers in metallic glasses and liquids

    Science.gov (United States)

    Chen, David Z.; An, Qi; Goddard, William A.; Greer, Julia R.

    2017-01-01

    The atomic-level structures of liquids and glasses are amorphous, lacking long-range order. We characterize the atomic structures by integrating radial distribution functions (RDF) from molecular dynamics (MD) simulations for several metallic liquids and glasses: C u46Z r54 , N i80A l20 , N i33.3Z r66.7 , and P d82S i18 . Resulting cumulative coordination numbers (CN) show that metallic liquids have a dimension of d =2.55 ±0.06 from the center atom to the first coordination shell and metallic glasses have d =2.71 ±0.04 , both less than 3. Between the first and second coordination shells, both phases crossover to a dimension of d =3 , as for a crystal. Observations from discrete atom center-of-mass position counting are corroborated by continuously counting Cu glass- and liquid-phase atoms on an artificial grid, which accounts for the occupied atomic volume. Results from Cu grid analysis show short-range d =2.65 for Cu liquid and d =2.76 for Cu glass. Cu grid structures crossover to d =3 at ξ ˜8 Å (˜3 atomic diameters). We study the evolution of local structural dimensions during quenching and discuss its correlation with the glass transition phenomenon.

  5. Metallic glass thin films for potential biomedical applications.

    Science.gov (United States)

    Kaushik, Neelam; Sharma, Parmanand; Ahadian, Samad; Khademhosseini, Ali; Takahashi, Masaharu; Makino, Akihiro; Tanaka, Shuji; Esashi, Masayoshi

    2014-10-01

    We introduce metallic glass thin films (TiCuNi) as biocompatible materials for biomedical applications. TiCuNi metallic glass thin films were deposited on the Si substrate and their structural, surface, and mechanical properties were investigated. The fabricated films showed good biocompatibility upon exposure to muscle cells. Also, they exhibited an average roughness of films was shown to be free from Ni and mainly composed of a thin titanium oxide layer, which resulted in the high surface biocompatibility. In particular, there was no cytotoxicity effect of metallic glass films on the C2C12 myoblasts and the cells were able to proliferate well on these substrates. Low cost, viscoelastic behavior, patternability, high electrical conductivity, and the capability to coat various materials (e.g., nonbiocompatible materials) make TiCuNi as an attractive material for biomedical applications.

  6. Structural evolution and strength change of a metallic glass at different temperatures

    Science.gov (United States)

    Tong, X.; Wang, G.; Stachurski, Z. H.; Bednarčík, J.; Mattern, N.; Zhai, Q. J.; Eckert, J.

    2016-08-01

    The structural evolution of a Zr64.13Cu15.75Ni10.12Al10 metallic glass is investigated in-situ by high-energy synchrotron X-ray radiation upon heating up to crystallization. The structural rearrangements on the atomic scale during the heating process are analysed as a function of temperature, focusing on shift of the peaks of the structure factor in reciprocal space and the pair distribution function and radial distribution function in real space which are correlated with atomic rearrangements and progressing nanocrystallization. Thermal expansion and contraction of the coordination shells is measured and correlated with the bulk coefficient of thermal expansion. The characteristics of the microstructure and the yield strength of the metallic glass at high temperature are discussed aiming to elucidate the correlation between the atomic arrangement and the mechanical properties.

  7. Explosive boiling of a metallic glass superheated by nanosecond pulse laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, M. Q., E-mail: mqjiang@imech.ac.cn, E-mail: lhdai@lnm.imech.ac.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Münster 48149 (Germany); Wei, Y. P. [Key Laboratory of Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wilde, G. [Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Münster 48149 (Germany); Dai, L. H., E-mail: mqjiang@imech.ac.cn, E-mail: lhdai@lnm.imech.ac.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-01-12

    We report an explosive boiling in a Zr-based (Vitreloy 1) bulk metallic glass irradiated by a nanosecond pulse laser with a single shot. This critical phenomenon is accompanied by the ejection of high-temperature matter from the target and the formation of a liquid-gas spinodal pattern on the irradiated area. An analytical model reveals that the glassy target experiences the normal heating (melting) and significant superheating, eventually culminating in explosive boiling near the spinodal limit. Furthermore, the time lag of nucleation and the critical radius of vapor bubbles are theoretically predicted, which are in agreement with the experimental observations. This study provides the investigation on the instability of a metallic glass liquid near the thermodynamic critical temperature.

  8. Electrical Resistance Measurement of Glass Transition and Crystallization Characteristics of Zr-Al-Cu-Ni Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper, glass transition and thermal stability of the Zr-Al-Cu-Ni metallic glasses were investigated by using electrical resistance measurement (ERM), DSC and X-ray diffraction techniques. The experimental results show that the ERM is capable of detecting the glass transition of the amorphous alloys and can help to distinguish the crystallization products of the Zr-Al-Cu-Ni metallic glasses owing to the difference of the electrical resistivity between the precipitation phases.

  9. GENERATION OF A COMPOSITE GLASS-METAL ROD: PRACTICAL RESULTS

    Directory of Open Access Journals (Sweden)

    Gridasova Ekaterina Alexandrovna

    2012-10-01

    Full Text Available Glass has a high compressive strength and low impact strength. The strength of glass in compression is a lot higher than the strength of glass in tension, and it varies within the range of 500-1,250 MPa. Whenever the glass is in compression, it can compete with the properties of metal in terms of its strength. The tensile strength of glass under tension is 30-50 MPa. The reason for that is the fact that the strength of glass is strongly dependent on the state of its surface. Methods of increasing the strength of glass have been the subject of research projects implemented at Far Eastern Federal University. The objective is to apply compressive stresses that would prevent any defects in the surface layer and harden the surface to improve the glass resistance to mechanical stresses and isolate it from the environment. Creation of a composite rod made of glass grade C49-1 (3С5Na and steel E235C (ISO standard manufactured through the employment of diffusion bonding represents a practical result of the research. Its analysis has proven the presence of full contact, absence of cracks and poor penetration alongside the welding zone. Microscopy methods of analysis have demonstrated the presence of the transition zone in the points of interface of materials. The results of the spectral analysis prove the penetration of Fe-cations into the glass down to the depth of 30 microns. The chemical analysis of the zone of diffusion proves that the crystalline structure, or fayalite (Fe2SiO4, is formed in the glass. The rod strength analysis has demonstrated its high compressive

  10. 含B2-CuZr相CuZr基块体金属玻璃复合材料应变速率敏感性的变化%Strain Rate Sensitivity Variation in CuZr-based Bulk Metallic Glass Composites Containing B2-CuZr Phase

    Institute of Scientific and Technical Information of China (English)

    魏然; 昌云; 杨森; 张长军; 贺林

    2016-01-01

    通过应变速率跳跃模式下的单轴压缩试验,研究了含有不同体积分数B2-CuZr相的CuZr基块体金属玻璃复合材料的应变速率敏感性.结果发现,随着B2-CuZr相体积分数的增加,在3.7×10-5s-1至3.7×10-3 s-1的应变速率范围中,该复合材料的应变速率敏感指数可由负值变化为正值.但是,对于B2-CuZr相体积分数高达约80%的复合材料,其应变速率敏感指数的正值仍然是反常的低.这一现象与B2-CuZr相自身力学行为所呈现的有限应变速率依赖性有关,是由于变形过程中B2-CuZr相的马氏体相变效应所致.研究结果显示,CuZr基块体金属玻璃复合材料的极限应变速率敏感性受制于B2-CuZr相.%The strain rate sensitivity (SRS) of CuZr-based bulk metallic glass composites (BMGCs) containing a B2-CuZr phase with different volume fractions was investigated by performing uniaxial compression tests in a strain-rate-jump mode.It is found that the SRS exponents of the BMGCs can vary from negative to positive in the strain-rate range from 3.7× 10-5 s-1 to 3.7× 103 s-1 with increasing of the B2-CuZr phase volume fraction.However,the positive SRS exponent of the BMGC with a higher B2-CuZr phase volume fraction up to about 80% is still unexpectedly low.This is attributed to the limited strain-rate-dependence of mechanical behavior of the B2-CuZr phase,which is induced by the martensitic transformation effect of the phase during deformation.It is obvious that the SRS ceiling of the CuZr-based BMGCs is controlled by the B2-CuZr phase.

  11. Soft-ferromagnetic bulk glassy alloys with large magnetostriction and high glass-forming ability

    Directory of Open Access Journals (Sweden)

    Jiawei Li

    2011-12-01

    Full Text Available The effect of Dy addition on the glass-forming ability (GFA, magnetostriction as well as soft-magnetic properties and fracture strength in FeDyBSiNb glassy alloys was investigated. In addition to the increase of supercooled liquid region from 55 to 100 K, the addition of Dy is effective in approaching alloy to an eutectic point and increasing the saturation magnetostrction (λs. Accordingly, bulk glassy alloy (BGA rods with diameters up to 4 mm were produced, which exhibit a large λs as high as 65×10-6. Besides, the BGA system exhibits superhigh fracture strength of 4000 MPa, combined with good soft-magnetic properties.

  12. Structural disorder in metallic glass-forming liquids

    OpenAIRE

    Shao-Peng Pan; Shi-Dong Feng; Li-Min Wang; Jun-Wei Qiao; Xiao-Feng Niu; Bang-Shao Dong; Wei-Min Wang; Jing-Yu Qin

    2016-01-01

    We investigated structural disorder by a new structural parameter, quasi-nearest atom (QNA), in atomistic configurations of eight metallic glass-forming systems generated through molecular dynamics simulations at various temperatures. Structural analysis reveals that the scaled distribution of the number of QNA appears to be an universal property of metallic liquids and the spatial distribution of the number of QNA displays to be clearly heterogeneous. Furthermore, the new parameter can be di...

  13. The study of devitrification processes in heavy-metal fluoride glasses.

    Science.gov (United States)

    Dunkley, Ian R; Smith, Reginald W; Varma, Sudhanshu

    2004-11-01

    Heavy-metal fluoride glasses are very promising optical fiber materials because of their predicted ultralow loss and long transparency range. Although conventional silica fibers have attained their theoretical minimum loss of 0.15 dB/km, fluoride glasses have the potential to yield losses of only 0.001 dB/km. Fluoride glasses also exhibit transparency into mid-IR frequencies, a region inaccessible to silica fibers. However, this group of glasses is very unstable to devitrification during both bulk glass synthesis and fiber-drawing. This instability has limited their commercial exploitation to a small niche market in the laser industry. The ZBLAN glass (53ZrF(4)-20BaF(2)-4LaF(3)-3AlF(3)-20NaF) is the most promising of these materials since its fiber-drawing region lies on the edge, or possibly just outside its crystallization region. It is believed that additional research into understanding the nucleation mechanics involved in the devitrification of fluoride glasses will lead to the development of technology to suppress such nucleation, or at least minimize the associated crystallization temperature region, allowing high optical quality fibers to be produced. It has recently been demonstrated that a microgravity environment can suppress devitrification in ZBLAN glass preform preparation, and that devitrification may be reduced when preparing ZBLAN terrestrially in a containerless facility. It is believed that the role of viscosity is critical in the devitrification mechanism of ZBLAN glass and in determining the optimum fiber-drawing temperature. Unfortunately, viscosity data for fluoride glasses are only available above the melting point and around the glass transition. A piezoelectric viscometer has been developed and is being used to determine the missing viscosity data in the fiber-drawing and crystallization temperature regions. Shear thinning of the glasses and/or the application of hydrostatic pressure on the glasses have been recently proposed to be

  14. Soldering of Thin Film-Metallized Glass Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Hernandez, C.L.; Glass, S.J.

    1999-03-31

    The ability to produce reliable electrical and structural interconnections between glass and metals by soldering was investigated. Soldering generally requires premetallization of the glass. As a solderable surface finish over soda-lime-silicate glass, two thin films coatings, Cr-Pd-Au and NiCr-Sn, were evaluated. Solder nettability and joint strengths were determined. Test samples were processed with Sn60-Pb40 solder alloy at a reflow temperature of 210 C. Glass-to-cold rolled steel single lap samples yielded an average shear strength of 12 MPa. Solder fill was good. Control of the Au thickness was critical in minimizing the formation of AuSn{sub 4} intermetallic in the joint, with a resulting joint shear strength of 15 MPa. Similar glass-to-glass specimens with the Cr-Pd-Au finish failed at 16.5 MPa. The NiCr-Sn thin film gave even higher shear strengths of 20-22.5 MPa, with failures primarily in the glass.

  15. Diffusion between glass and metals for optical fiber preform extrusion

    Science.gov (United States)

    Yeo, Felicia Yan Xin; Zhang, Zhifeng; Kumar Chakkathara Janardhanan Nair, Dileep; Zhang, Yilei

    2015-07-01

    When silica is extruded, diffusion of metal atoms into silica results contamination to the silica being heated, and thus is a serious concern for the glass extrusion process, such as extrusion of glass fiber preform. This paper examines diffusion between fused silica and two high strength metals, the stainless steel SS410 and the superalloy Inconel 718, at 1000 °C and under the normal atmosphere condition by SEM and Electron Dispersion Spectrum. It is found that diffusion occurs between silica and SS410, and at the same time, SS410 is severely oxidized during diffusion experiment. On the contrary, the diffusion between Inconel 718 and silica is unnoticeable, suggesting excellent high temperature performance of Inconel 718 for glass extrusion.

  16. Process, structure, property and applications of metallic glasses

    Directory of Open Access Journals (Sweden)

    B. Geetha Priyadarshini

    2016-07-01

    Full Text Available Metallic glasses (MGs are gaining immense technological significance due to their unique structure-property relationship with renewed interest in diverse field of applications including biomedical implants, commercial products, machinery parts, and micro-electro-mechanical systems (MEMS. Various processing routes have been adopted to fabricate MGs with short-range ordering which is believed to be the genesis of unique structure. Understanding the structure of these unique materials is a long-standing unsolved mystery. Unlike crystalline counterpart, the outstanding properties of metallic glasses owing to the absence of grain boundaries is reported to exhibit high hardness, excellent strength, high elastic strain, and anti-corrosion properties. The combination of these remarkable properties would significantly contribute to improvement of performance and reliability of these materials when incorporated as bio-implants. The nucleation and growth of metallic glasses is driven by thermodynamics and kinetics in non-equilibrium conditions. This comprehensive review article discusses the various attributes of metallic glasses with an aim to understand the fundamentals of relationship process-structure-property existing in such unique class of material.

  17. Key factors affecting mechanical behavior of metallic glass nanowires

    Science.gov (United States)

    Zhang, Qi; Li, Qi-Kai; Li, Mo

    2017-01-01

    Both strengthening and weakening trends with decreasing diameter have been observed for metallic glass nanowires, sometimes even in the samples with the same chemical composition. How to reconcile the results has reminded a puzzle. Since the detailed stress state and microstructure of metallic glass nanowires may differ from each other significantly depending on preparation, to discover the intrinsic size effect it is necessary to study metallic glass nanowires fabricated differently. Here we show the complex size effects from one such class of metallic glass nanowires prepared by casting using molecular dynamics simulations. As compared with the nanowires of the same composition prepared by other methods, the cast nanowires deform nearly homogeneously with much lower strength but better ductility; and also show strengthening in tension but weakening in compression with decreasing wire diameter. The subtle size dependence is shown to be related to the key factors including internal and surface stress state, atomic structure variation, and presence of various gradients. The complex interplay of these factors at decreasing size leads to the different deformation behaviors.

  18. Electrical switching in bulk samples of 0. 15As-0. 12Ge-0. 73Te glass

    Energy Technology Data Exchange (ETDEWEB)

    Eckels, D.E.

    1976-06-01

    Switching in bulk samples of 0.15As--0.12Ge--0.73Te glass is found to be caused predominantly by the thermal switching mechanism for near threshold applied voltages. Switching also occurred by the thermal mechanism even for applied voltages an order of magnitude above the threshold voltage of the sample. In order to investigate a switching event in this glass sample, a constant voltage pulse was applied to the sample and the delay time and the electrical energy input to the sample during the delay time measured. A log--log plot of the energy input to the sample during a delay time of 1.00 s as a function of the electrode spacing on the sample's surface was found to have a slope of approximately 1.6. For the theoretical study of the thermal switching mechanism, a one-dimensional calculation of the heat balance equation with radial heat flow was made and the results of the calculation followed the same trends as the experimental data. The large scatter in parts of the data and the increase in the average resistance of the sample for a switching event with near threshold applied voltages could not be explained by the thermal switching mechanism. These effects could be a manifestation of the structural changes which probably occur in the sample as a result of the high temperatures present at the moment of switching. 33 fig.

  19. Structural Characterization of Carbon Nanomaterial Film In Situ Synthesized on Various Bulk Metals

    Directory of Open Access Journals (Sweden)

    J. Y. Xu

    2014-01-01

    Full Text Available Carbon nanofiber films were prepared via a simple chemical vapor deposition (CVD method on various bulk metal substrates including bulk 316 L stainless steel, pure cobalt, and pure nickel treated by surface mechanical attrition treatment (SMAT. The microstructures of the carbon nanomaterial film were studied by SEM, TEM, XRD, and Raman spectroscopy. In this paper, bulk metallic materials treated by SMAT served as substrates as well as catalysts for carbon nanomaterial film formation. The results indicate that the carbon nanofiber films are formed concerning the catalytic effects of the refined metallic particles during CVD on the surface of SMAT-treated bulk metal substrates. However, distinguished morphologies of carbon nanomaterial film are displayed in the case of the diverse bulk metal substrates.

  20. Glass transition of polymers in bulk, confined geometries, and near interfaces

    Science.gov (United States)

    Napolitano, Simone; Glynos, Emmanouil; Tito, Nicholas B.

    2017-03-01

    When cooled or pressurized, polymer melts exhibit a tremendous reduction in molecular mobility. If the process is performed at a constant rate, the structural relaxation time of the liquid eventually exceeds the time allowed for equilibration. This brings the system out of equilibrium, and the liquid is operationally defined as a glass—a solid lacking long-range order. Despite almost 100 years of research on the (liquid/)glass transition, it is not yet clear which molecular mechanisms are responsible for the unique slow-down in molecular dynamics. In this review, we first introduce the reader to experimental methodologies, theories, and simulations of glassy polymer dynamics and vitrification. We then analyse the impact of connectivity, structure, and chain environment on molecular motion at the length scale of a few monomers, as well as how macromolecular architecture affects the glass transition of non-linear polymers. We then discuss a revised picture of nanoconfinement, going beyond a simple picture based on interfacial interactions and surface/volume ratio. Analysis of a large body of experimental evidence, results from molecular simulations, and predictions from theory supports, instead, a more complex framework where other parameters are relevant. We focus discussion specifically on local order, free volume, irreversible chain adsorption, the Debye–Waller factor of confined and confining media, chain rigidity, and the absolute value of the vitrification temperature. We end by highlighting the molecular origin of distributions in relaxation times and glass transition temperatures which exceed, by far, the size of a chain. Fast relaxation modes, almost universally present at the free surface between polymer and air, are also remarked upon. These modes relax at rates far larger than those characteristic of glassy dynamics in bulk. We speculate on how these may be a signature of unique relaxation processes occurring in confined or heterogeneous polymeric

  1. Ti或Al添加对Zr50Cu50非晶合金/W润湿行为和界面特性的影响%EFFECTS OF THE ADDITION OF Ti OR Al ON THE WETTING BEHAVIORS AND INTERFACIAL CHARACTERISTICS OF Zr50Cu50 BULK METALLIC GLASS/W SUBSTRATE

    Institute of Scientific and Technical Information of China (English)

    马国峰; 贺春林; 李正坤; 张波; 李宏; 张海峰; 胡壮麒

    2013-01-01

    采用座滴法研究了在真空条件下,Al或Ti对Cu50Zr50非晶合金与W基片之间的润湿行为和界面结合状态的影响.借助SEM和XRD分析了添加Al或Ti对Cu50Zr50非晶合金/W界面微观结构和界面结合机制的影响.结果表明:Al或Ti的添加有利于降低Cu50Zr50非晶合金熔体的表面张力,从而改善了其与W之间的润湿性;在实验范围内,Cu50Zr50非晶合金/w界面附近有新相ZrW2生成,添加Al或Ti对Cu50Zr50非晶合金/W界面微观结构的影响不同,Al的添加促进了界面反应的进行,随着Al的添加量增加,界面反应产物ZrW2相在界面处形成的连续反应层减小,而在熔体中富Al且贫Cu的相中析出的量增大.Ti的添加抑制了界面反应的进行,随着Ti的添加量增加,界面反应物ZrW2逐渐消失,进而使界面结合机制由最初的溶解扩散和界面反应型混合机制转变为单独的溶解扩散型.%In order to get the good performance of metal W reinforced Zr-based bulk metallic glass (BMG) matrix composites, it is necessary to understand the effects of alloy elements on the wettability between Zr-based BMG and W substrate. In this work, the effects of the addition of Ti or Al on the wetting behaviors and interracial characteristics of Zr50Cu50 BMG on W substrate were studied at different temperatures in a high vacuum by using a sessile drop technique. The SEM and XRD were used to analyze the microstructure and bonding mechanism of the Zr50Cu50 BMG / W interface with the addition of Ti or Al element. The results show that the wetting angle of Zr50Cu50 molten alloy on W substrate decreases with increasing content of Ti or Al in liquid Zr50Cu50 and experimental temperature. The wettability of Zr50Cu50 BMG on W substrates is improved because the surface tension of Zr50Cu50 molten alloy decreases with increasing content of Ti or Al. It is found that the behavior between Zr50Cu50 BMG and W substrate is reactive wetting in nature, and there exists a new

  2. Crystalline Precipitate in a Bulk Glass Forming Zr-Based Alloy and Its Effect on Mechanical Properties

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Cylindrical and sheet samples of bulk metallic glass with a nominal composition of Zr52.5Ni14.6Al10Cu17.9Ti5 (at. pct) were prepared by melt injection casting. The crystalline precipitates formed during the casting were studied by metallographic observations and selected-area electron diffractions. The effect of crystalline precipitates on the mechanical properties were investigated by tensile and compressive tests at room temperature. Oxygen contents and the sample sizes (or cooling rates) strongly affect the formation of the crystalline precipitates. Overheating the alloy melt up to 200 K above its melting temperature can effectively prevent the formation of the crystalline precipitates to get fully glass samples with diameters up to 2 mm for cylinders and thickness up to 1 mm for sheets even the oxygen content is as higher as 0.08 wt pct.With increasing the sample sizes, the crystalline precipitates increase in volume fraction and size. The formation of the precipitates experienced two stages, i.e., initially nucleation and isotropic growth, and then anisotropic growth, finally forming faceted morphologies. Fully glassy Zr52.5Ni14.6Al10Cu17.9Ti5 alloy exhibits excellent tensile and compressive properties at room temperature. The presence of crystalline precipitates significantly decreases the tensile and compressive properties. With increasing the crystalline precipitates, the area of vein patterns on the fracture surface decreases, but the fracture steps increase, and the fracture mode changes from ductile to brittle resulting from the larger stress concentration caused by the larger sizes and faceted shapes of the crystalline precipitates.

  3. Direct observation of bulk second-harmonic generation inside a glass slide with tightly focused optical fields

    Science.gov (United States)

    Wang, Xianghui; Fardad, Shima; Das, Susobhan; Salandrino, Alessandro; Hui, Rongqing

    2016-04-01

    Bulk second-harmonic generation (SHG) inside glass slides is directly detected unambiguously without interference from surface contributions. This is enabled by tightly focused and highly localized ultrashort laser pulses. The theoretical calculations based on vector diffraction theory and the phenomenological model of SHG inside centrosymmetric materials agree well with the measured far-field SHG radiation patterns for different polarization states of the fundamental beam. The results indicate that the observed bulk SHG is predominantly related to the bulk parameter δ' and originates from the three-dimensional field gradient in the focal region.

  4. STRUCTURAL INTERACTIONS OF HYDROGEN WITH BULK AMORPHOUS MICROSTRUCTURES IN METALLIC SYSTEMS UNDERSTANDING THE ROLE OF PARTIAL CRYSTALLINITY ON PERMEATION AND EMBRITTLEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Kyle; Fox, Elise; Korinko, Paul; Adams, Thad

    2010-05-10

    The development of metallic glasses in bulk form has led to a resurgence of interest into the utilization of these materials for a variety of applications. A potentially exciting application for these bulk metallic glass (BMG) materials is their use as composite membranes to replace high cost Pd/Pd-alloy membranes for enhanced gas separation processes. One of the major drawbacks to the industrial use of Pd/Pd-alloy membranes is that during cycling above and below a critical temperature an irreversible change takes place in the palladium lattice structure which can result in significant damage to the membrane. Furthermore, the cost associated with Pd-based membranes is a potential detractor for their continued use and BMG alloys offer a potentially attractive alternative. Several BMG alloys have been shown to possess high permeation rates, comparable to those measured for pure Pd metal. In addition, high strength and toughness when either in-situ or ex-situ second phase dispersoids are present. Both of these properties, high permeation and high strength/toughness, potentially make these materials attractive for gas separation membranes that could resist hydrogen 'embrittlement'. However, a fundamental understanding of the relationship between partially crystalline 'structure'/devitrification and permeation/embrittlement in these BMG materials is required in order to determine the operating window for separation membranes and provide additional input to the material synthesis community for improved alloy design. This project aims to fill the knowledge gap regarding the impact of crystallization on the permeation properties of metallic glass materials. The objectives of this study are to (i) determine the crystallization behavior in different gas environments of Fe and Zr based commercially available bulk metallic glass and (ii) quantify the effects of partial crystallinity on the hydrogen permeation properties of these metallic glass membranes.

  5. Glass-metal objects from archaeological excavation: corrosion study

    Science.gov (United States)

    Greiner-Wronowa, Elżbieta; Zabiegaj, Dominika; Piccardo, Paolo

    2013-12-01

    This paper contributes to the investigations on history, technology, and degradation of middle age objects (metallic rings with mounted glass beads) recently excavated under the Main Square in Krakow (Poland). Moreover, they were discovered in soil layers differing by chemical composition and microclimate parameters. Historical material is indeed very limited in terms of quantity and sample size, and the following nondestructive analyses were applied: scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and X-ray fluorescence spectroscopy (XRF). The glass and the metal were separately tested. Metallography on cross-sections (by both optical and scanning electron microscopy) was applied only on microfragments sampled from metallic rings. The achieved results pointed out how the local microclimate affected the degradation of the analyzed rings developing locally different corrosion processes. Each tested glass of "ring eye" shows a specific chemical composition. All glass pieces were covered by silica gel, and locally more advanced corrosion has been found.

  6. Influence of pulsing current on the glass transition and crystallizing kinetics of a Zr base bulk amorphous alloy

    Institute of Scientific and Technical Information of China (English)

    WU Wenfei; YAO Kefu; ZHAO Zhankui

    2004-01-01

    Based on the thermal analysis, the influence of pulsing current on the glass transition and crystallizing kinetics of Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy has been studied. The obtained results show that after the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy was pretreated by high-density pulsing current at low temperature, its glass transition temperature Tg, the initial crystallizing temperature Tx and the corresponding exothermic peak of crystallization Tpi were reduced. But the temperature range of supercooled liquid ΔT=Tx-Tg is almost the same. The calculated results with Kissinger equation show that the activation energy of glass transition of the alloy pretreated is reduced significantly, while the activation energy of crystallization is basically unchanged. The influence of pulsing current on the glass transition and crystallization of the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk amorphous alloy is believed to be related with the structure relaxation of the glass caused by the current.

  7. Search for the microscopic origin of defects and shear localization in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mo

    2001-11-10

    This proposed research addresses one of the long outstanding fundamental problems in materials science, the mechanisms of deformation in amorphous metals. Due to the lack of long-range translational order, details of structural defects and their behaviors in metallic glasses have not been accessible in experiments. In addition, the small dimensions of the amorphous alloys made early by rapid quenching impose severe limit on many standard mechanical and microscopy testing. As a result, the microscopic mechanism of deformation in the amorphous materials has not been established. The recent success in synthesis of bulk metallic glass overcomes the difficulty in standard testing; but the barrier for understanding the defect process and microscopic mechanisms of deformation still remains. Amorphous metals deform in a unique way by shear banding. As a result, there is no work hardening, little macroscopic plasticity, and catastrophic failure. To retain and improve the inherent high strength, large elastic strain, and high toughness in amorphous metals, a variety of synthesis activities are currently underway including making metallic glass matrix composites. These new explorations call for a quantitative understanding of deformation mechanisms in both the monolithic metallic glasses as well as their composites. The knowledge is expected to give insight and guide to design, processing and applications of this new generation of engineering materials. This DOE funded research takes the approach of computer simulation and modeling to tackle this problem. It is expected that with the increasing power of computers, the numerical modeling could provide the answers that are difficult or impossible to get from experiments. Three parallel research tasks were planned in this work. One is on search of atomic structural defects and other microscopic mechanisms underlying the deformation process. The second is the formulate a general model to describe shear localization, shear band

  8. Isochronal and Isothermal Crystallization in Zr57.5 Cu27.3 Al8.5 Ni6.7 Bulk Metallic Glass%Zr57.5Cu27.3 Al8.5 Ni6.7非晶合金的非等温和等温晶化动力学研究

    Institute of Scientific and Technical Information of China (English)

    陈振华; 赵秀媛; 王辉平; 张昊; 陈鼎

    2015-01-01

    Non-isothermal crystallization transformation kinetics and isothermal crystallization kinetics of prepared Zr57 .5 Cu27 .3 Al8.5 Ni6 .7 bulk metallic glass (BMG)were investigated with differential scanning calorimetry (DSC).In isochronal mode,the values of activation energy,E g ,E x ,E p 1 and E p2 ,calculated by Kisinger method are 409.70 kJ/mol (± 60.07 kJ/mol),335.53 kJ/mol (± 39.94 kJ/mol),323.95 kJ/mol (± 15.21 kJ/mol)and 187.75 kJ/mol (± 13.27 kJ/mol),respectively.In isothermal mode,the S-shape relation curves of crystalline volume fraction and temperature reveal the typical transition of nuclea-tion and growth.The Avrami exponent n ranges from 3.0 to 4,indicating the crystallization mechanism in the Zr57 .5 Cu27 .3 Al8.5 Ni6 .7 BMG is mainly interface-controlled.The crystal growth way changes from two-di-mensional growth with decreased nucleation rate to three-dimensional growth in the isothermal crystalliza-tion process.In isothermal mode,the mean value of activation energy is 434.81 kJ/mol,which is higher than that in the isochronal mode.%对制备的Zr57.5Cu27.3Al8.5Ni6.7非晶合金的等温与非等温晶化动力学通过差式扫描量热法(DSC)进行了研究,根据Kisinger方程计算出Zr57.5Cu27.3Al8.5Ni6.7非晶合金在非等温条件下的激活能Eg,Ex,Ep1和Ep2,分别为409.70kJ/mol(±60.07kJ/mol),335.53kJ/mol(±39.94kJ/mol),323.95kJ/mol(±15.21kJ/mol)和187.75kJ/mol(±13.27kJ/mol).在718K,723K,728K和733K等温条件下得到的晶化体积分数与时间的关系曲线呈“S”型,表明晶化过程为典型的形核长大型转变.Avrami指数n的范围为3≤n≤4,表明晶化过程由界面控制的二维长大转变为界面控制的三维长大,形核率随时间逐渐降低至稳定,等温晶化过程得到的激活能平均值434.81kJ/mol,高于非等温晶化过程的有效激活能.

  9. ‘Crystal Genes’ in Metallic Liquids and Glasses

    Science.gov (United States)

    Sun, Yang; Zhang, Feng; Ye, Zhuo; Zhang, Yue; Fang, Xiaowei; Ding, Zejun; Wang, Cai-Zhuang; Mendelev, Mikhail I.; Ott, Ryan T.; Kramer, Matthew J.; Ho, Kai-Ming

    2016-03-01

    We analyze the underlying structural order that transcends liquid, glass and crystalline states in metallic systems. A genetic algorithm is applied to search for the most common energetically favorable packing motifs in crystalline structures. These motifs are in turn compared to the observed packing motifs in the actual liquid or glass structures using a cluster-alignment method. Using this method, we have revealed the nature of the short-range order in Cu64Zr36 glasses. More importantly, we identified a novel structural order in the Al90Sm10 system. In addition, our approach brings new insight into understanding the origin of vitrification and describing mesoscopic order-disorder transitions in condensed matter systems.

  10. Bacterial adhesion to glass and metal-oxide surfaces.

    Science.gov (United States)

    Li, Baikun; Logan, Bruce E

    2004-07-15

    Metal oxides can increase the adhesion of negatively-charged bacteria to surfaces primarily due to their positive charge. However, the hydrophobicity of a metal-oxide surface can also increase adhesion of bacteria. In order to understand the relative contribution of charge and hydrophobicity to bacterial adhesion, we measured the adhesion of 8 strains of bacteria, under conditions of low and high-ionic strength (1 and 100 mM, respectively) to 11 different surfaces and examined adhesion as a function of charge, hydrophobicity (water contact angle) and surface energy. Inorganic surfaces included three uncoated glass surfaces and eight metal-oxide thin films prepared on the upper (non-tin-exposed) side of float glass by chemical vapor deposition. The Gram-negative bacteria differed in lengths of lipopolysaccharides on their outer surface (three Escherichia coli strains), the amounts of exopolysaccharides (two Pseudomonas aeruginosa strains), and their known relative adhesion to sand grains (two Burkholderia cepacia strains). One Gram positive bacterium was also used that had a lower adhesion to glass than these other bacteria (Bacillus subtilis). For all eight bacteria, there was a consistent increase in adhesion between with the type of inorganic surface in the order: float glass exposed to tin (coded here as Si-Sn), glass microscope slide (Si-m), uncoated air-side float glass surface (Si-a), followed by thin films of (Co(1-y-z)Fe(y)Cr(z))3O4, Ti/Fe/O, TiO2, SnO2, SnO2:F, SnO2:Sb, A1(2)O3, and Fe2O3 (the colon indicates metal doping, a slash indicates that the metal is a major component, while the dash is used to distinguish surfaces). Increasing the ionic strength from 1 to 100 mM increased adhesion by a factor of 2.0 +/- 0.6 (73% of the sample results were within the 95% CI) showing electrostatic charge was important in adhesion. However, adhesion was not significantly correlated with bacterial charge and contact angle. Adhesion (A) of the eight strains was

  11. Elastic properties and atomic bonding character in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Rouxel, T., E-mail: tanguy.rouxel@univ-rennes1.fr [Institut de Physique de Rennes, IPR, UMR-CNRS 6251, Université de Rennes, campus de Beaulieu, 35042 Rennes cedex (France); Yokoyama, Y. [Cooperative Research and Development Center for Advanced Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-07-28

    The elastic properties of glasses from different metallic systems were studied in the light of the atomic packing density and bonding character. We found that the electronegativity mismatch (Δe{sup −}) between the host- and the major solute-elements provides a plausible explanation to the large variation observed for Poisson's ratio (ν) among metallic glasses (MGs) (from 0.28 for Fe-based to 0.43 for Pd-based MGs), notwithstanding a similar atomic packing efficiency (C{sub g}). Besides, it is found that ductile MGs correspond to Δe{sup −} smaller than 0.5 and to a relatively steep atomic potential well. Ductility is, thus, favored in MGs exhibiting a weak bond directionality on average and opposing a strong resistance to volume change.

  12. Energy model for the Zr-based metallic glass alloy melt with clusters

    Institute of Scientific and Technical Information of China (English)

    YANG YuanSheng; LI HuiQiang; TONG WenHui

    2007-01-01

    An energy model for the melt of bulk metallic glass (BMG) with clusters was established, the Gibbs free energy and interfacial energy for the Zr-Al-Ni ternary alloy melt with Zr2Ni clusters were calculated, and the effects of the clusters on the Gibbs free energy, interfacial energy and nucleation rate were analyzed. The results showed that the existence of the clusters in the Zr-Al-Ni ternary alloy melt enables the Gibbs free energy to decrease in the composition range where bulk metallic glass forms easily, makes the interfacial energy increase and changes the distribution of the interfacial energy with the alloy composition. Because of the clusters in the melt, the Gibbs free energy of the Zr66Al8Ni26 alloy melt decreases about 0.3-1 kJ/mol and the interfacial energy between the melt and crystal nucleus increases about 0.016 J/m2. The nucleation rate of the undercooled Zr66Al8Ni26 alloy melt decreases evidently under the influence of the clusters on Gibbs free energy and the interfacial energy, and the maximum of the nucleation rate in the melt with the Zr2Ni clusters is only about 107 mol-1·s-1.

  13. Phase field crystal modelling of the order-to-disordered atomistic structure transition of metallic glasses

    Science.gov (United States)

    Zhang, W.; Mi, J.

    2016-03-01

    Bulk metallic glass composites are a new class of metallic alloy systems that have very high tensile strength, ductility and fracture toughness. This unique combination of mechanical properties is largely determined by the presence of crystalline phases uniformly distributed within the glassy matrix. However, there have been very limited reports on how the crystalline phases are nucleated in the super-cooled liquid and their growth dynamics, especially lack of information on the order-to-disordered atomistic structure transition across the crystalline-amorphous interface. In this paper, we use phase field crystal (PFC) method to study the nucleation and growth of the crystalline phases and the glass formation of the super cooled liquid of a binary alloy. The study is focused on understanding the order-to-disordered transition of atomistic configuration across the interface between the crystalline phases and amorphous matrix of different chemical compositions at different thermal conditions. The capability of using PFC to simulate the order-to-disorder atomistic transition in the bulk material or across the interface is discussed in details.

  14. Energy model for the Zr-based metallic glass alloy melt with clusters

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An energy model for the melt of bulk metallic glass (BMG) with clusters was estab- lished, the Gibbs free energy and interfacial energy for the Zr-Al-Ni ternary alloy melt with Zr2Ni clusters were calculated, and the effects of the clusters on the Gibbs free energy, interfacial energy and nucleation rate were analyzed. The results showed that the existence of the clusters in the Zr-Al-Ni ternary alloy melt enables the Gibbs free energy to decrease in the composition range where bulk metallic glass forms easily, makes the interfacial energy increase and changes the distribu- tion of the interfacial energy with the alloy composition. Because of the clusters in the melt, the Gibbs free energy of the Zr66Al8Ni26 alloy melt decreases about 0.3-1 kJ/mol and the interfacial energy between the melt and crystal nucleus increases about 0.016 J/m2. The nucleation rate of the undercooled Zr66Al8Ni26 alloy melt de- creases evidently under the influence of the clusters on Gibbs free energy and the interfacial energy, and the maximum of the nucleation rate in the melt with the Zr2Ni clusters is only about 107 mol1s1.

  15. Structural Characteristics and Crystallization of Metallic Glass Sputtered Films by Using Zr System Target

    Directory of Open Access Journals (Sweden)

    Katsuyoshi Kondoh

    2008-01-01

    Full Text Available Zr-Al-Ni-Cu thin films were deposited by the radio-frequency sputtering method at low substrate temperature using three kinds of targets: Zr55Al10Ni5Cu30 bulk metallic glass target (α-BMG target, crystallized bulk metallic glass target (c-BMG target, and an elemental composite target composed of each Zr, Al, Ni chips, and Cu plate. XRD profiles of the films prepared when using these targets indicated that all of the films showed amorphous structures. While XRD profiles of the films using α- and c-BMG targets revealed a broad peak of 2θ=38 degree in the same way as the α-BMG target indicating amorphous structures, that of the film using elemental composite targets showed a broad peak of 2θ=42 degree, which is higher compared to the latter material. As a result of annealing the films at various temperatures for 900 seconds, the film using the α-BMG target showed a crystallization temperature of 748 K, higher than that of BMG with 723 K, while the other films had lower crystallization temperatures below 723 K. XRD profiles also indicated that the crystallized compounds of the films were different from those of BMG target.

  16. Co-based soft magnetic bulk glassy alloys optimized for glass-forming ability and plasticity

    Indian Academy of Sciences (India)

    LI LI; HUAIJUN SUN; YUNZHANG FANG; JIANLONG ZHENG

    2016-06-01

    Co-based bulk glassy alloys (BGAs) have become more and more important because of their nearly zero magnetostriction and high giant magneto-impedance effect. Here, we report the improvement of glass-formingability (GFA), soft-magnetic properties and plasticity by a small addition of Mo atoms in CoFeBSiNbMo BGAs.(Co$_{0.6}$Fe$_{0.4}$)$_{69}$B$_{20.8}$Si$_{5.2}$Nb$_{5−x}$Mo$_{x}$ ferromagnetic BGA cylindrical glassy rods were fabricated successfully with adiameter of 5 mm by conventional copper mould casting method. It reveals that the substitution of a small amount of Mo for Nb makes the composition to approach a eutectic point and effectively enhances the GFA of alloy. Inaddition to high GFA and superhigh strength, the compressive test shows that the Mo addition can improve the plasticity for the obtained BGAs. The combination of high GFA, excellent soft-magnetic properties and good plasticitydemonstrated in our alloys is promising for the future applications as functional materials.

  17. Atomic structures of Zr-based metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The atomic structures of Zr-Ni and Zr-Ti-Al-Cu-Ni metallic glasses were investigated by using classical molecular dynamic (MD),reverse Monte Carlo (RMC),ab initio MD (AIMD) simulations and high resolution transmission electron microscopy (HRTEM) techniques. We focused on the short-range order (SRO) and medium-range order (MRO) in the glassy structure. It is shown that there are icosahedral,FCC-and BCC-type SROs in the Zr-based metallic glasses. A structural model,characterized by imperfect ordered packing (IOP),was proposed based on the MD simulation and confirmed by the HRTEM observation. Furthermore,the evolution from IOP to nanocrystal during the crystallization of metallic glasses was also ex-plored. It is found that the growth from IOP to nanocrystal proceeds through three distinct stages: the formation of quasi-ordered structure with one-dimensional (1D) periodicity,then 2D periodicity,and finally the formation of 3D nanocrystals. It is also noted that these three growth steps are crosslinked.

  18. Metallic Glass Formation by Ion Mixing and Calculation of Glass-Forming-Ability from Inter-Atomic Potential in the Binary Metal Systems

    Institute of Scientific and Technical Information of China (English)

    LI Zhengcao; LAI Wensheng; LIU Baixin

    2001-01-01

    In this article,a brief summary of the up-to-date progress of metallic glass formation by ion mixing of metallic multilayers in the binary metal systems is first presented.Secondly,thermodynamic modeling of metallic glass formation is developed with special consideration of the interfacial free energy of the multilayers.Thirdly,results of molecular dynamics simulations for some representative systems are presented to show the calculation of the glass-forming ability directly from the inter-atomic potential of the binary metal systems.

  19. Lasing effects in new Nd3+-doped TeO2-Nb2O5-WO3 bulk glasses

    Science.gov (United States)

    Carreaud, J.; Labruyère, A.; Dardar, H.; Moisy, F.; Duclère, J.-R.; Couderc, V.; Bertrand, A.; Dutreilh-Colas, M.; Delaizir, G.; Hayakawa, T.; Crunteanu, A.; Thomas, P.

    2015-09-01

    This paper demonstrates for the first time continuous wave (cw) and pulsed lasing effects in a 75TeO2-20NbO2.5-5WO3 glass doped with 1 mol.% in Nd3+. It is divided into two parts: The first part treats all the aspects related to the elaboration and the characterization of the materials. Thus, glasses elaborated within the TeO2-Nb2O5-WO3 ternary system show a rather high glass transition temperature Tg ∼ 375 °C, with an excellent thermal stability of ∼160 °C. Compared to glasses synthesized in either TeO2-Nb2O5 or TeO2-WO3 binary systems, glasses fabricated within such system show improved mechanical performances, with larger Young's modulus values. The structural characteristics of the samples, studied by Raman spectroscopy, are also presented. Linear optical properties (refractive index and extinction coefficient) are accessed by spectroscopic ellipsometry. As well, the optical transmission of the various bulk glasses is measured, in the case of both uncoated and coated glasses. In particular, specific anti-reflective coatings at 808 nm (laser diode pump wavelength) and 1064 nm (laser emission wavelength) are respectively deposited on the two surfaces of the sample in order to minimize the losses due to Fresnel reflections at the two glass/air interfaces. In addition, another specific surface treatment (Rmax at 1064 nm) was employed to serve as the back mirror of the laser cavity. The optical transmission data testified to the real efficiency of all these coatings. Finally, the photoluminescence properties (emission and excitation spectra, and luminescence decay curve) of the Nd3+-doped glasses, measured at room temperature for bulk samples, and as a function of temperature for powder glasses, are discussed. The second part is focused on evidencing (cw) and pulsed lasing effects in such coated bulk lasers. Cylindric samples of only a few millimeters in height and in diameter were tested and led to a laser emission around 1064 nm, characterized by a very low

  20. Devitrification kinetics and phase selection mechanisms in Cu-Zr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-01

    Metallic glasses have been a promising class of materials since their discovery in the 1960s. Indeed, remarkable chemical, mechanical and physical properties have attracted considerable attention, and several excellent reviews are available. Moreover, the special group of glass forming alloys known as the bulk metallic glasses (BMG) become amorphous solids even at relatively low cooling rates, allowing them to be cast in large cross sections, opening the scope of potential applications to include bulk forms and net shape structural applications. Recent studies have been reported for new bulk metallic glasses produced with lower cooling rates, from 0.1 to several hundred K/s. Some of the application products of BMGs include sporting goods, high performance springs and medical devices. Several rapid solidification techniques, including melt-spinning, atomization and surface melting have been developed to produce amorphous alloys. The aim of all these methods is to solidify the liquid phase rapidly enough to suppress the nucleation and growth of crystalline phases. Furthermore, the production of amorphous/crystalline composite (ACC) materials by partial crystallization of amorphous precursor has recently given rise to materials that provide better mechanical and magnetic properties than the monolithic amorphous or crystalline alloys. In addition, these advances illustrate the broad untapped potential of using the glassy state as an intermediate stage in the processing of new materials and nanostructures. These advances underlie the necessity of investigations on prediction and control of phase stability and microstructural dynamics during both solidification and devitrification processes. This research presented in this dissertation is mainly focused on Cu-Zr and Cu-Zr-Al alloy systems. The Cu-Zr binary system has high glass forming ability in a wide compositional range (35-70 at.% Cu). Thereby, Cu-Zr based alloys have attracted much attention according to fundamental

  1. Polaronic Transport in Phosphate Glasses Containing Transition Metal Ions

    Science.gov (United States)

    Henderson, Mark

    The goal of this dissertation is to characterize the basic transport properties of phosphate glasses containing various amounts of TIs and to identify and explain any electronic phase transitions which may occur. The P2 O5-V2O5-WO3 (PVW) glass system will be analyzed to find the effect of TI concentration on conduction. In addition, the effect of the relative concentrations of network forming ions (SiO2 and P2O5) on transport will be studied in the P2O5-SiO2-Fe2O 3 (PSF) system. Also presented is a numerical study on a tight-binding model adapted for the purposes of modelling Gaussian traps, mimicking TI's, which are arranged in an extended network. The results of this project will contribute to the development of fundamental theories on the electronic transport in glasses containing mixtures of transition oxides as well as those containing multiple network formers without discernible phase separation. The present study on the PVW follows up on previous investigation into the effect on mixed transition ions in oxide glasses. Past research has focused on glasses containing transition metal ions from the 3d row. The inclusion of tungsten, a 5d transition metal, adds a layer of complexity through the mismatch of the energies of the orbitals contributing to localized states. The data have indicated that a transition reminiscent of a metal-insulator transition (MIT) occurs in this system as the concentration of tungsten increases. As opposed to some other MIT-like transitions found in phosphate glass systems, there seems to be no polaron to bipolaron conversion. Instead, the individual localization parameter for tungsten noticeably decreases dramatically at the transition point as well as the adiabaticity. Another distinctive feature of this project is the study of the PSF system, which contains two true network formers, phosphorous pentoxide (P2O 5) and silicon dioxide (SiO2). It is not usually possible to do a reliable investigation of the conduction properties of

  2. Healing of interfaces of high and ultra-high-molecular- weight polystyrene below the bulk glass transition temperature

    DEFF Research Database (Denmark)

    Boiko, Yuri M.; Lyngaae-Jørgensen, Jørgen

    2004-01-01

    into contact to themselves below the glass transition temperature T-g of the bulk Tg-bulk, in a lap-shear joint geometry, at a constant healing temperature T-h for a healing time t(h) of 10 min to 24 h. The lap-shear strength sigma of the symmetric HMWPS-HMWPS and UHMWPS-URMWPS interfaces has been measured...... at the ambient temperature. Larger values of sigma have always been measured for the HMWPS-HMWPS interface after healing at the same conditions. However, the difference between the values of a, for the HMWPS-HMWPS and UHMWPS-UHMWPS interfaces observed at T-h = Tg-bulk - 33 degreesC and T-h = Tg-bulk - 23 degrees......C became negligible at T-h = Tg-bulk - 13 degreesC at long times. The kinetics of strength evolution at the two interfaces involved at T-h = Tg-bulk - 33 degreesC and T-h = Tg-bulk - 23 degreesC was found to follow the form sigma proportional to (t(h))(1/4)(M-n)(-1/4), in accordance with the minor chain...

  3. Marcus Electron Transfer Reactions with Bulk Metallic Catalysis

    CERN Document Server

    Widom, A; Srivastava, Y N

    2015-01-01

    Electron transfer organic reaction rates are considered employing the classic physical picture of Marcus wherein the heats of reaction are deposited as the energy of low frequency mechanical oscillations of reconfigured molecular positions. If such electron transfer chemical reaction events occur in the neighborhood of metallic plates, then electrodynamic interface fields must also be considered in addition to mechanical oscillations. Such electrodynamic interfacial electric fields in principle strongly effect the chemical reaction rates. The thermodynamic states of the metal are unchanged by the reaction which implies that metallic plates are purely catalytic chemical agents.

  4. Review on progressive microforming of bulk metal parts directly using sheet metals (Keynote Paper

    Directory of Open Access Journals (Sweden)

    Fu M.W.

    2015-01-01

    Full Text Available Due to the ubiquitous trend of product miniaturization, energy saving and weight reduction, micro/meso-scale parts have been widely used in many industrial clusters. Micromanufacturing processes for production of such micro/meso-scale parts are thus critically needed. Microforming, as one of these micro manufacturing processes, is a promising process and thus got many explorations and researches. Compared with the research on size effect affected deformation behaviours, less attention has been paid to the process development for mass production of micro-parts. The product quality and fabrication productivity of micro-parts depend on the involved process chain. To address the difficulty in handling and transporting of the micro-sized workpiece, development of a progressive microforming process for directly fabricating bulk micro-parts using sheet metals seems quite promising as it avoids or facilitates billet handling, transportation, positioning, and ejection in the process chain. In this paper, an intensive review on the latest development of progressive microforming technologies is presented. First of all, the paper summarizes the characteristic of progressive microforming directly using sheet metal. The size effect-affected deformation behaviour and the dimensional accuracy, deformation load, ductile fracture, and the surface finish of the microformed parts by progressive microforming using sheet metals are then presented. Finally, some research issues from the implementation of mass production perspective are also discussed.

  5. Single agglutinates: A comparative study of compositions of agglutinitic glass, whole-grain, bulk soil, and FMR

    Science.gov (United States)

    Basu, A.; Robinson, R.; Mckay, D. S.; Blanchard, D. P.; Morris, R. V.; Wentworth, Susan J.

    1994-01-01

    Previous workers on single agglutinates have variously interpreted the composition of agglutinitic glass to represent impact melts of (1) bulk soil, (2) mixed components in finer sizes, and (3) microtargets. Separately, Papike has argued in favor of fusion of the finest fraction of bulk soils. Thirty-four single agglutinates were hand-picked from the mature Apollo 16 soil 61181 (I(sub s)/FeO = 82) and the FMR and chemical composition (INAA for Fe, Sc, Sm, Co, Ni, and Cr) of each agglutinate particle were measured. Thirteen of these single agglutinates were selected for electron beam microanalysis and imaging. Less than 1 micron spots were analyzed (for Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, Mn, Fe, Ni, and Ba) on pure glassy areas (approximately ten in each particle) selected on the basis of optical and BSE images (avoiding all clasts and inclusions) with an electron microprobe to obtain average glass compositions of each single agglutinate.

  6. Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Kim S.-Y.

    2015-06-01

    Full Text Available Porous metallic materials have been widely used in many fields including aerospace, atomic energy, electro chemistry and environmental protection. Their unique structures make them very useful as lightweight structural materials, fluid filters, porous electrodes and catalyst supports. In this study, we fabricated Ni-based porous metallic glasses having uniformly dispersed micro meter pores by the sequential processes of ball-milling and chemical dissolution method. We investigated the application of our porous metal supported for Pt catalyst. The oxidation test was performed in an atmosphere of 1% CO and 3% O2. Microstructure observation was performed by using a scanning electron microscope. Oxidation properties and BET (Brunauer, Emmett, and Teller were analyzed to understand porous structure developments. The results indicated that CO Oxidation reaction was dependent on the specific surface area.

  7. Preparation and mechanism study of bulk pure rare-earth metals with amorphous and nanocrystalline structures

    Institute of Scientific and Technical Information of China (English)

    LI ErDong; SONG XiaoYan; ZHANG JiuXing; LU NianDuan

    2007-01-01

    The preparation and the mechanism study of bulk pure rare-earth metals with amorphous and nanocrystalline structures, which were produced by spark plasma sintering (SPS), were carried out in this paper. With different processing parameters, the amorphous, two phases of amorphous and nanocrystalline, and complete nanocrystalline microstructures have been obtained. The nano-grain sizes in the bulk nanocrystalline materials are found smaller than the original powder particles sizes, which may change the conventional viewpoint that the grains in the sintered bulk are generally coarser than the raw powder particles. The technique developed in the present work can be extended to the preparation of many other nano bulk metal materials, and thus enables the studies of the nano-size effects on the physical, chemical and mechanical properties of bulk nano materials.

  8. Corrosion of Metal Inclusions In Bulk Vitrification Waste Packages. Erratum

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Gary L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-06

    This report refers to or contains Kg values for glasses LAWA44, LAWB45 and LAWC22 affected by calculations errors as identified by Papathanassiu et al. (2011). The corrected Kg values are reported in an erratum included in the revised version of the original report. The revised report can be referenced as follows: Pierce E. M. et al. (2004) Waste Form Release Data Package for the 2005 Integrated Disposal Facility Performance Assessment. PNNL-14805 Rev. 0 Erratum. Pacific Northwest National Laboratory, Richland, WA, USA.

  9. Corrosion of Metal Inclusions In Bulk Vitrification Waste Packages Erratum

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Gary L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-06

    This report refers to or contains Kg values for glasses LAWA44, LAWB45 and LAWC22 affected by calculations errors as identified by Papathanassiu et al. (2011). The corrected Kg values are reported in an erratum included in the revised version of the original report. The revised report can be referenced as follows: Pierce E. M. et al. (2004) Waste Form Release Data Package for the 2005 Integrated Disposal Facility Performance Assessment. PNNL-14805 Rev. 0 Erratum. Pacific Northwest National Laboratory, Richland, WA, USA.

  10. Sodium enrichment on glass surface during heating of heavy-metal-containing glasses under a reductive atmosphere

    Directory of Open Access Journals (Sweden)

    Takashi Okada

    2015-01-01

    Full Text Available Sodium enrichment occurs on the surface of the glass that is in contact with the gas phase during the heat treatment of lead-containing glass under a reductive atmosphere. This technique was previously found to promote lead recovery in waste-glass treatment, and may be potentially applied to glasses containing other heavy metal oxides. Thus, the efficiencies of sodium enrichment were compared among glasses with different heavy metal species (PbO, CuO, and ZnO in the heat-treatment under a CO-containing atmosphere. The sodium enrichment efficiencies in the treatment of the PbO- and CuO-containing glasses were higher than that in the treatment of the ZnO containing glass. This was because the efficiencies were related to the reduction of the heavy metal oxides. The mass ratio of Na to Si on the glass surface increased as the PbO concentration decreased via reduction of PbO. The sodium-rich phase was separated together with a copper-concentrated phase that was generated via the reduction of CuO. However, ZnO in the glass is thermodynamically more difficult to reduce in the CO-containing atmosphere used in the study, resulting in the lower efficiency of the sodium enrichment.

  11. Metal oxide films on glass and steel substrates

    CERN Document Server

    Sohi, A M

    1987-01-01

    in the pH8 electrolyte supports the view that the rate limiting reduction reaction is possibly oxygen (or water) reduction although some contribution from an organic 'impurity' cannot be ruled out. Coatings of Fe sub 3 O sub 4 on mild steel have been prepared by CVD using pneumatic spraying techniques and the corrosion behaviour of coated electrodes in organic-phosphate electrolyte (pH8) has been examined. A variety of thin (10-1000nm) metal oxide films have been deposited on flat glass substrates by the pyrolysis of an aerosol of metal acetylacetonates in a suitable carrier. The optical characteristics and thickness of the films have been measured and particular interest has centered on the use of a novel pin on disc apparatus to measure the physical durability of such thin films. Characteristic friction/penetration force traces have been established for 1st Series transition metal oxide films and some ranking in terms of 'hardness' established. The use of SnO sub 2 - coated glass for electrodes in a light m...

  12. Investigation of Partially Crystalline Zr77Ni23 Metallic Glass

    Directory of Open Access Journals (Sweden)

    Amra Salčinović Fetić

    2016-08-01

    Full Text Available This paper presents the results of an extensive research of partially crystalline Zr77Ni23 metallic glass (indicated numbers refer to atomic percentages. The partially crystalline Zr77Ni23 samples were prepared by melt-spinning using a device constructed in the Metal Physics Laboratory, Faculty of Science in Sarajevo. XRD pattern shows crystalline peaks which correspond to an orthorhombic structure of Zr3Ni superimposed on an amorphous pattern. Homogeneity and chemical composition were investigated using scanning electron microscopy (SEM and energy-dispersive X-ray spectroscopy (EDX. Crystallization was studied by differential scanning calorimetry (DSC. DSC analysis indicated a simple thermally activated process. Overall activation energy of the crystallization was calculated using Kissinger's model for nonisothermal process and compared with those given by the Augis-Bennett model. By monitoring of the electrical resistance in the temperature range 80 – 270 K a small and negative thermal coefficient of electrical resistance was observed. This means that electrical resistance varies slightly with temperature and it makes this metallic glass suitable for application in electronic circuits for which this property is an important requirement.

  13. Investigation of preparation methods on surface/bulk structural relaxation and glass fragility of amorphous solid dispersions.

    Science.gov (United States)

    Ke, Peng; Hasegawa, Susumu; Al-Obaidi, Hisham; Buckton, Graham

    2012-01-17

    The objective of this study was to investigate the effect of preparation methods on the surface/bulk molecular mobility and glass fragility of solid dispersions. Solid dispersions containing indomethacin and PVP K30 were chosen as the model system. An inverse gas chromatography method was used to determine the surface structural relaxation of the solid dispersions and these data were compared to those for bulk relaxation obtained by DSC. The values of τ(β) for the surface relaxation were 4.6, 7.1 and 1.8h for melt quenched, ball milled and spray dried solid dispersions respectively, compared to 15.6, 7.9 and 9.8h of the bulk. In all systems, the surface had higher molecular mobility than the bulk. The glass fragility of the solid dispersions was also influenced by the preparation methods with the most fragile system showing the best stability. The zero mobility temperature (T(0)) was used to correlate with the physical stability of the solid dispersions. Despite having similar T(g) (65°C), the T(0) of the melt quenched, ball milled and spray dried samples were 21.6, -4.2 and 16.7°C respectively which correlated well with their physical stability results. Therefore, T(0) appears to be a better indicator than T(g) for predicting stability of amorphous materials.

  14. SPP propagation in nonlinear glass-metal interface

    KAUST Repository

    Sagor, Rakibul Hasan

    2011-12-01

    The non-linear propagation of Surface-Plasmon-Polaritons (SPP) in single interface of metal and chalcogenide glass (ChG) is considered. A time domain simulation algorithm is developed using the Finite Difference Time Domain (FDTD) method. The general polarization algorithm incorporated in the auxiliary differential equation (ADE) is used to model frequency-dependent dispersion relation and third-order nonlinearity of ChG. The main objective is to observe the nonlinear behavior of SPP propagation and study the dynamics of the whole structure. © 2011 IEEE.

  15. The kinetic origin of delayed yielding in metallic glasses

    Science.gov (United States)

    Ye, Y. F.; Liu, X. D.; Wang, S.; Fan, J.; Liu, C. T.; Yang, Y.

    2016-06-01

    Recent experiments showed that irreversible structural change or plasticity could occur in metallic glasses (MGs) even within the apparent elastic limit after a sufficiently long waiting time. To explain this phenomenon, a stochastic shear transformation model is developed based on a unified rate theory to predict delayed yielding in MGs, which is validated afterwards through extensive atomistic simulations carried out on different MGs. On a fundamental level, an analytic framework is established in this work that links time, stress, and temperature altogether into a general yielding criterion for MGs.

  16. Spin-exchange interaction between transition metals and metalloids in soft-ferromagnetic metallic glasses

    Science.gov (United States)

    Das, Santanu; Choudhary, Kamal; Chernatynskiy, Aleksandr; Choi Yim, Haein; Bandyopadhyay, Asis K.; Mukherjee, Sundeep

    2016-06-01

    High-performance magnetic materials have immense industrial and scientific importance in wide-ranging electronic, electromechanical, and medical device technologies. Metallic glasses with a fully amorphous structure are particularly suited for advanced soft-magnetic applications. However, fundamental scientific understanding is lacking for the spin-exchange interaction between metal and metalloid atoms, which typically constitute a metallic glass. Using an integrated experimental and molecular dynamics approach, we demonstrate the mechanism of electron interaction between transition metals and metalloids. Spin-exchange interactions were investigated for a Fe-Co metallic glass system of composition [(Co1-x Fe x )0.75B0.2Si0.05]96Cr4. The saturation magnetization increased with higher Fe concentration, but the trend significantly deviated from simple rule of mixtures. Ab initio molecular dynamics simulation was used to identify the ferromagnetic/anti-ferromagnetic interaction between the transition metals and metalloids. The overlapping band-structure and density of states represent ‘Stoner type’ magnetization for the amorphous alloys in contrast to ‘Heisenberg type’ in crystalline iron. The enhancement of magnetization by increasing iron was attributed to the interaction between Fe 3d and B 2p bands, which was further validated by valence-band study.

  17. Effect of Heating Rate on Glass Foaming: Transition to Bulk Foam

    Energy Technology Data Exchange (ETDEWEB)

    Hrma, Pavel R.

    2009-02-15

    Foaming of glass is an undesirable side effect of glass fining. According to a recent experimental study, the gas-phase volume in the melt heated at a constant rate dramatically increased with an increased rate of heating. This observation indicates that an increased rate of heating (a natural consequence of the increased processing rate experienced as a result of transition to oxy-fuel firing) may exert a substantial influence on glass foaming in advanced glass-melting furnaces. This paper attributes this effect to the change of mode of foam formation in response to an increased rate of heating.

  18. Formation and crystallization of Zr-Ni-Ti metallic glass

    Institute of Scientific and Technical Information of China (English)

    刘雄军; 惠希东; 焦建廷; 陈国良

    2004-01-01

    The metallic Zr65 Ni25 Ti10 (mole fraction, %) glass has been fabricated by a single roller melt-spinning method. The glass forming ability(GFA) and thermal stability of the Zr65 Ni25 Ti10 melt-spun ribbons were investiga ted by using X-ray diffraction(XRD) and differential scanning calorimetry(DSC) in the mode of continuous heating.It is shown that the reduced glass transition temperature (Trg) is 0. 506 and the supercooled liquid region (△Tx) is 30 K. Two exothermic peaks were observed in the DSC curves of the as-quenched ribbon, which indicates that the crystallization process undergoes two different stages. The phase transformation during the isothermal annealing was investigated by X-ray diffraction(XRD) and transmission electronic microscope(TEM). It is observed that the meta stable FCC Zr2 Ni(Fd3m, α= 12.27 (A)) precipitated while annealing in the suppercooled region(615 K) and the stable BCT Zr2Ni(I4/mcm, α=6. 499 (A), c=5. 270 (A)) precipitated while annealing at higher temperature(673 K or 723K). The crystallines are on nanoscale, with grain size of 15 -30 nm. The reason for the precipitation of the different structural Zr2 Ni from the glassy matrix under different annealing conditions was discussed based on the concept of multi-component chemical short range order(MCSRO).

  19. Terbium-doped heavy metal glasses for green luminescence

    Institute of Scientific and Technical Information of China (English)

    L.Zur; J. Pisarska; W.A. Pisarski

    2011-01-01

    Compositional-dependent heavy metal lead borate glasses doped with Tb3+ ior were investigated.Green luminescence related to main 5D4→7F5 (543 nm) transition was registered under excitation of 5D3 state of Tb3+ ions.Based on excitation and luminescence measurements,several spectroscopic parameters for Tb3+ ions were examined as a function of heavy metal PbO content.Luminescence decay analysis indicated that the 5D4 luminescence lifetime of Tb3+ reduced from 2.83 to 1.42 ms,when PbO:B2O3 ratio was changed from 1:1 to 4:1.

  20. SET and RESET states of As2Se3 doped GeTe4 bulk glasses probed by Raman spectroscopy

    Science.gov (United States)

    Pumlianmunga, Ramesh, K.

    2016-12-01

    Te based chalcogenide glasses are being explored for non-volatile memory applications. We report the electrical switching studies on bulk Ge0.20Te0.80 glass alloyed with As0.40Se0.60 in different proportions. The addition of As0.40Se0.60 increases the electrical resistivity and the threshold voltage of (As0.4Se0.6)x(Ge0.2Te0.8)1-x glasses in the composition range 0 ≤ x ≤ 0.40. Glasses in the range 0 ≤ x ≤ 0.10 are found to exhibit memory switching, whereas glasses with x ≥ 0.15 exhibit threshold switching. The memory (SET) state can be brought back to RESET state by passing a current of 3-5 mA. Particularly, the glass with x = 0.10 is identified to be very stable, and it can be cycled between the SET and RESET state consistently with 3 mA current. The Raman spectra of SET and RESET states indicate that the SET sample has GeTe and Te crystalline units while the structure of RESET state is analogous to the as-quenched glass. Interestingly, the variation in the local structure is minimal for SET and RESET states for x = 0.10. And also the resistance of the SET state is relatively high. So they can be set to RESET state with less current and can be explored for low power phase change memory applications.

  1. Simulation of cooling and solidification of three-dimensional bulk borosilicate glass: effect of structural relaxations

    Science.gov (United States)

    Barth, N.; George, D.; Ahzi, S.; Rémond, Y.; Joulaee, N.; Khaleel, M. A.; Bouyer, F.

    2014-02-01

    The modeling of the viscoelastic stress evolution and specific volume relaxation of a bulky glass cast is presented in this article and is applied to the experimental cooling process of an inactive nuclear waste vitrification process. The concerned borosilicate glass is solidified and cooled down to ambient temperature in a stainless steel canister, and the thermomechanical response of the package is simulated. There exists a deviant compression of the liquid core due to the large glass package compared to standard tempered glass plates. The stress load development of the glass cast is finally studied for different thermal load scenarios, where the cooling process parameters or the final cooldown rates were changed, and we found a great influence of the studied cooldown rates on the maximum stress build-up at ambient temperature.

  2. Instability Analysis and Free Volume Simulations of Shear Band Directions and Arrangements in Notched Metallic Glasses

    Science.gov (United States)

    Li, Weidong; Gao, Yanfei; Bei, Hongbin

    2016-10-01

    As a commonly used method to enhance the ductility in bulk metallic glasses (BMGs), the introduction of geometric constraints blocks and confines the propagation of the shear bands, reduces the degree of plastic strain on each shear band so that the catastrophic failure is prevented or delayed, and promotes the formation of multiple shear bands. The clustering of multiple shear bands near notches is often interpreted as the reason for improved ductility. Experimental works on the shear band arrangements in notched metallic glasses have been extensively carried out, but a systematic theoretical study is lacking. Using instability theory that predicts the onset of strain localization and the free-volume-based finite element simulations that predict the evolution of shear bands, this work reveals various categories of shear band arrangements in double edge notched BMGs with respect to the mode mixity of the applied stress fields. A mechanistic explanation is thus provided to a number of related experiments and especially the correlation between various types of shear bands and the stress state.

  3. Instability Analysis and Free Volume Simulations of Shear Band Directions and Arrangements in Notched Metallic Glasses

    Science.gov (United States)

    Li, Weidong; Gao, Yanfei; Bei, Hongbin

    2016-01-01

    As a commonly used method to enhance the ductility in bulk metallic glasses (BMGs), the introduction of geometric constraints blocks and confines the propagation of the shear bands, reduces the degree of plastic strain on each shear band so that the catastrophic failure is prevented or delayed, and promotes the formation of multiple shear bands. The clustering of multiple shear bands near notches is often interpreted as the reason for improved ductility. Experimental works on the shear band arrangements in notched metallic glasses have been extensively carried out, but a systematic theoretical study is lacking. Using instability theory that predicts the onset of strain localization and the free-volume-based finite element simulations that predict the evolution of shear bands, this work reveals various categories of shear band arrangements in double edge notched BMGs with respect to the mode mixity of the applied stress fields. A mechanistic explanation is thus provided to a number of related experiments and especially the correlation between various types of shear bands and the stress state. PMID:27721462

  4. On the correlation between microscopic structural heterogeneity and embrittlement behavior in metallic glasses.

    Science.gov (United States)

    Li, Weidong; Gao, Yanfei; Bei, Hongbin

    2015-10-05

    In order to establish a relationship between microstructure and mechanical properties, we systematically annealed a Zr-based bulk metallic glass (BMG) at 100 ~ 300 °C and measured their mechanical and thermal properties. The as-cast BMG exhibits some ductility, while the increase of annealing temperature and time leads to the transition to a brittle behavior that can reach nearly-zero fracture energy. The differential scanning calorimetry did not find any significant changes in crystallization temperature and enthalpy, indicating that the materials still remained fully amorphous. Elastic constants measured by ultrasonic technique vary only slightly with respect to annealing temperature and time, which does obey the empirical relationship between Poisson's ratio and fracture behavior. Nanoindentation pop-in tests were conducted, from which the pop-in strength mapping provides a "mechanical probe" of the microscopic structural heterogeneities in these metallic glasses. Based on stochastically statistic defect model, we found that the defect density decreases with increasing annealing temperature and annealing time and is exponentially related to the fracture energy. A ductile-versus-brittle behavior (DBB) model based on the structural heterogeneity is developed to identify the physical origins of the embrittlement behavior through the interactions between these defects and crack tip.

  5. Annealing-induced shape recovery in thin film metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Negussie, Alemu Tesfaye; Diyatmika, Wahyu [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Chu, J.P., E-mail: jpchu@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Shen, Y.L. [Department of Mechanical Engineering, University of New Mexico, Albuquerque, NM 87131 (United States); Jang, J.S.C. [Department of Mechanical Engineering, National Central University, Chung-Li 32001, Taiwan (China); Hsueh, C.H. [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-11-15

    Highlights: • Annealing-induced shape recovery of thin film metallic glass is examined. • Shape recovery becomes obvious with increasing temperature and holding time. • Minimum roughness is obtained when annealed within supercooled liquid region. • The amount of free volume in the film plays a role for the shape recovery. • The numerical simulation confirms the shape recovery upon annealing. - Abstract: The shape recovery property of a sputtered Zr{sub 50.3}Cu{sub 28.1}Al{sub 14}Ni{sub 7.6} (in at.%) thin film metallic glass upon heating is examined. Due to the surface tension-driven viscous flow, the shape of indentation appears to recover to different extents at various temperatures and holding times. It is found that a maximum of 59.8% indentation depth recovery is achieved after annealing within the supercooled liquid region (SCLR). The amount of free volume in the film is found to play a role in the recovery. Atomic force microscopy results reveal a decrease in film roughness to a minimum value within SCLR. To elucidate the experimentally observed shape recovery, a numerical modeling has been employed. It is evident that the depressed region caused by indentation is elevated after annealing.

  6. Giant enhancement of magnetocaloric effect in metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    WANG YongTian; BAI HaiYang; PAN MingXiang; ZHAO DeQian; WANG WeiHua

    2008-01-01

    The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (△Sm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum △Sm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.

  7. Giant enhancement of magnetocaloric effect in metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (ΔSm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum ΔSm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.

  8. Local atomic structures of single-component metallic glasses

    Science.gov (United States)

    Trady, Salma; Hasnaoui, Abdellatif; Mazroui, M.'hammed; Saadouni, Khalid

    2016-10-01

    In this study we examine the structural properties of single-component metallic glasses of aluminum. We use a molecular dynamics simulation based on semi-empirical many-body potential, derived from the embedded atom method (EAM). The radial distribution function (RDF), common neighbors analysis method (CNA), coordination number analysis (CN) and Voronoi tessellation are used to characterize the metal's local structure during the heating and cooling (quenching). The simulation results reveal that the melting temperature depends on the heating rate. In addition, atomic visualization shows that the structure of aluminum after fast quenching is in a glassy state, confirmed quantitatively by the splitting of the second peak of the radial distribution function, and by the appearance of icosahedral clusters observed via CNA technique. On the other hand, the Wendt-Abraham parameters are calculated to determine the glass transition temperature (Tg), which depends strongly on the cooling rate; it increases while the cooling rate increases. On the basis of CN analysis and Voronoi tessellation, we demonstrate that the transition from the Al liquid to glassy state is mainly due to the formation of distorted and perfect icosahedral clusters.

  9. Non-Local Ductile Damage Formulations for Sheet Bulk Metal Forming

    Science.gov (United States)

    Beese, Steffen; Loehnert, Stefan; Wriggers, Peter

    2016-08-01

    A ductile damage model for sheet bulk metal forming processes and its efficient and accurate treatment in the context of the Finite Element Method is presented. The damage is introduced as a non-local field to overcome pathological mesh dependency. Since standard elements tend to show volumetric locking in the bulk forming process a mixed formulation is implemented in the commercial software simufact.forming to obtain better results.

  10. Trace metals in bulk precipitation and throughfall in a suburban area of Japan

    Science.gov (United States)

    Hou, H.; Takamatsu, T.; Koshikawa, M. K.; Hosomi, M.

    Throughfall and bulk precipitation samples were collected monthly for 1.5 years over bare land and under canopies of Japanese cedar ( Cryptomeria japonica), Japanese red pine ( Pinus densiflora), Japanese cypress ( Chamaecyparis obtusa), and bamboo-leafed oak ( Quercus myrsinaefolia) in a suburban area of Japan. Samples were analyzed for dissolved Al, Mn, Fe, Cu, Zn, Ag, In, Sn, Sb and Bi by ICP-AES and ICP-MS. The metal concentrations were higher in throughfall, especially that of C. japonica, than bulk precipitation. Enrichment ratios (ERs: ratios of metal concentrations in throughfall to those in bulk precipitation) ranged from 2.5 (Zn) to 5.3 (Ag) (3.9 on average), and ERs for slightly soluble metals were generally higher than those for easily soluble metals. Concentrations of Mn, Fe, Cu, and Zn accounted for 99% of the total concentration of heavy metals in rainwater, whereas those of rare metals such as Ag, In, Sn, and Bi totaled <0.23%. Average concentrations of rare metals were 0.002 and 0.010 μg l -1 for Ag, 0.001 and 0.005 μg l -1 for In, 0.062 and 0.21 μg l -1 for Sn, and 0.006 and 0.023 μg l -1 for Bi in bulk precipitation and throughfall, respectively. The metal concentrations in rainwater were negatively correlated to the volume of rainwater, indicating that washout is the main mechanism that incorporates metals into rainwater. From the enrichment factors, that is, (X/Al) rain/(X/Al) crust, metals other than Fe were shown to be more enriched in rainwater than in the Earth's crust, including those present as a result of leaching from soil dust (Mn) and from anthropogenic sources (Cu, Zn, Ag, In, Sn, Sb, and Bi).

  11. Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Zr41Ti14Cu12.5Ni10Be22.5 (at.%) bulk metallic glass composites with various crystallization fractions were prepared by pretreating the bulk metallic glassy samples with pulsing current, and then by isothermal annealing at near initial crystallization temperature for different periods of time. The precipitations and crystallization fractions were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and their effects on mechanical properties of the composite were studied by microhardness, uniaxial compression test and scanning electron microscopy (SEM). The experimental results show that the primary precipitate is quasicrystalline phase and other metastable phases including Be2Zr, Zr2Cu and FCC would precipitate subsequently. In the initial crystallization process, in which the crystallization fraction increases from 0 to 8.2%, both fracture strength and plastic strain increase, with the maximum plastic strain up to 6.4%. When the crystallization fraction is larger than 8.2%, the fracture strength and the plastic strain decrease sharply. Furthermore, the alloy with low crystallization fraction is fractured by shearing, while for high crystallization fraction it is fractured by splitting and cleavage. The results show that the mechanical properties of the glassy alloy could be optimized by controlling the processing parameters.

  12. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    Institute of Scientific and Technical Information of China (English)

    JIA You-Hun; ZHONG Biao; YIN Jian-Ping

    2009-01-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+-doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

  13. Effects of transition metal oxide doping on the structure of sodium metaphosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zotov, N.; Kirfel, A.; Beuneu, B.; Delaplane, R.; Hohlwein, D.; Reinauer, F.; Glaum, R

    2004-07-15

    Neutron diffraction measurements of transition metal-oxide-doped sodium metaphosphate glasses and melts show an anomalous increase of the first sharp diffraction peak both with increasing transition metal content and temperature due to progressive increase of the structural disorder.

  14. Dynamic Plastic Deformation (DPD): A Novel Technique for Synthesizing Bulk Nanostructured Metals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    While some superior properties of nanostructured materials (with structural scales below 100 nm) have attracted numerous interests of material scientists, technique development for synthesizing nanostructured metals and alloys in 3-dimensional (3D) bulk forms is still challenging despite of extensive investigations over decades.Here we report a novel synthesis technique for bulk nanostructured metals based on plastic deformation at high Zener-Hollomon parameters (high strain rates or low temperatures), i.e., dynamic plastic deformation (DPD).The basic concept behind this approach will be addressed together with a few examples to demonstrate the capability and characteristics of this method. Perspectives and future developments of this technique will be highlighted.

  15. Adaptive finite element-element-free Galerkin coupling method for bulk metal forming processes

    Institute of Scientific and Technical Information of China (English)

    Lei-chao LIU; Xiang-huai DONG; Cong-xin LI

    2009-01-01

    An adaptive finite element-element-free Galerkin (FE-EFG) coupling method is proposed and developed for the numerical simulation of bulk metal forming processes. This approach is able to adaptively convert distorted FE elements to EFG domain in analysis. A new scheme to implement adaptive conversion and coupling is presented. The coupling method takes both advantages of finite element method (FEM) and meshless methods. It is capable of handling large deformations with no need of remeshing procedures, while it is computationally more efficient than those full meshless methods. The effectiveness of the proposed method is demonstrated with the numerical simulations of the bulk metal forming processes including forging and extrusion.

  16. Densification and strain hardening of a metallic glass under tension at room temperature.

    Science.gov (United States)

    Wang, Z T; Pan, J; Li, Y; Schuh, C A

    2013-09-27

    The deformation of metallic glasses involves two competing processes: a disordering process involving dilatation, free volume accumulation, and softening, and a relaxation process involving diffusional ordering and densification. For metallic glasses at room temperature and under uniaxial loading, disordering usually dominates, and the glass can fail catastrophically as the softening process runs away in a localized mode. Here we demonstrate conditions where the opposite, unexpected, situation occurs: the densifying process dominates, resulting in stable plastic deformation and work hardening at room temperature. We report densification and hardening during deformation in a Zr-based glass under multiaxial loading, in a notched tensile geometry. The effect is driven by stress-enhanced diffusional relaxation, and is attended by a reduction in exothermic heat and hardening signatures similar to those observed in the classical thermal relaxation of glasses. The result is significant, stable, plastic, extensional flow in metallic glasses, which suggest a possibility of designing tough glasses based on their flow properties.

  17. Effect of metal impregnation in the field cool magnetization of bulk superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kita, M. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)]. E-mail: kita@istec.or.jp; Nariki, S. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan); Sakai, N. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan); Hirabayashi, I. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

    2006-10-01

    Gd-Ba-Cu-O bulk superconductors have significant potential for various applications due to the high critical current density and the highly trapped magnetic fields. Recently we have developed a large sized bulk superconductor using Gd210, which is discovered in the microgravity experiment. We investigated the mechanical properties and the cryostability of the Gd-Ba-Cu-O bulk superconductor to determine how to improve toughness and heat conduction of the large sized bulk superconductor. We introduced a stainless ring around the circumference of the bulk to increase the fracture strength of the bulk. Also, we introduced Al wires inserted in the hole along the c-axis of the bulk, and then the sample was subjected to the impregnation by using Bi-Sn-Cd alloy. We measured the trapped magnetic fields and the repulsive forces of the samples. The trapped magnetic field distributions were 1.13-1.36 T. The repulsive forces at 1 mm gap between the sample bulk and the permanent magnet with the surface magnetic induction of 0.37 T were about 70 N at 77 K. We have also measured the temperature dependence of the trapped magnetic field, and confirmed the effect of metal impregnation.

  18. Mesomorphic glass nanocomposites made of metal alkanoates and nanoparticles as emerging nonlinear-optical materials

    Science.gov (United States)

    Garbovskiy, Y.; Klimusheva, G.; Mirnaya, T.

    2016-09-01

    Mesomorphic metal alkanoates is very promising yet overlooked class of nonlinear-optical materials. Metal alkanoates can exhibit a broad variety of condensed states of matter including solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir-Blodgett films. Glass-forming properties of metal alkanoates combined with their use as nano-reactors and anisotropic host open up simple and efficient way to design various photonic nanomaterials. Despite very interesting physics, the experimental data on optical and nonlinearoptical properties of such materials are scarce. The goal of the present paper is to fill the gap by discussing recent advances in the field of photonic materials made of metal alkanoates, organic dyes, and nanoparticles. Optical and nonlinear-optical properties of the following materials are reviewed: (i) mesomorphic glass doped with organic dyes; (ii) smectic glass composed of cobalt alkanoates; (iii) semiconductor nanoparticles embedded in a glassy host; (iv) metal nanoparticles - glass (the cobalt octanoate) nanocomposites.

  19. Shear-banding Induced Indentation Size Effect in Metallic Glasses

    Science.gov (United States)

    Lu, Y. M.; Sun, B. A.; Zhao, L. Z.; Wang, W. H.; Pan, M. X.; Liu, C. T.; Yang, Y.

    2016-06-01

    Shear-banding is commonly regarded as the “plasticity carrier” of metallic glasses (MGs), which usually causes severe strain localization and catastrophic failure if unhindered. However, through the use of the high-throughput dynamic nanoindentation technique, here we reveal that nano-scale shear-banding in different MGs evolves from a “distributed” fashion to a “localized” mode when the resultant plastic flow extends over a critical length scale. Consequently, a pronounced indentation size effect arises from the distributed shear-banding but vanishes when shear-banding becomes localized. Based on the critical length scales obtained for a variety of MGs, we unveil an intrinsic interplay between elasticity and fragility that governs the nanoscale plasticity transition in MGs. Our current findings provide a quantitative insight into the indentation size effect and transition mechanisms of nano-scale plasticity in MGs.

  20. Thermal vibrations in the metallic glass Cu64Zr36

    Science.gov (United States)

    Schönfeld, Bernd; Zemp, Jérôme; Stuhr, Uwe

    2017-01-01

    Neutrons with 14.7 and 34 meV energy were used to determine the elastic and inelastic part of the structure factor for the metallic glass Cu64Zr36 at 250 K. Based on the temperature dependence of the elastic scattering between 150 K and RT, an average mean-square displacement =0.027(3) ~{{{\\mathringA}}2} at 250 K is obtained. The experimental scattering-vector dependence of inelastic scattering in reference to elastic scattering is found to be well described by the Debye model. Both results are supported by molecular dynamics simulations. A procedure is presented to separate the elastic part also in total x-ray scattering. This allows the smearing of structural information due to thermal vibrations to be eliminated.

  1. Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

    Science.gov (United States)

    Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

    2016-05-01

    Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can reveal salient microstructural features that cannot be observed from conventional metallographic techniques. Examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.

  2. Simulation of sheet-bulk metal forming processes with simufact.forming using user-subroutines

    Science.gov (United States)

    Beese, Steffen; Beyer, Florian; Blum, Heribert; Isik, Kerim; Kumor, Dustin; Löhnert, Stefan; Rademacher, Andreas; Tekkaya, A. Erman; Willner, Kai; Wriggers, Peter; Zeller, Sebastian

    2016-10-01

    In this article, we consider the simulation of sheet-bulk metal forming processes, which makes high demands on the underlying models and on the simulation software. We present our approach to incorporate new modelling approaches from various fields in a commercial simulation software, in our case Simufact.forming. Here, we discuss material, damage, and friction models as well as model adaptive techniques.

  3. Effects of aluminum nanocrystals on the corrosion resistance of aluminum-based metallic glasses

    Science.gov (United States)

    Lucente, Ashley Marie

    Aluminum-based metallic glasses possess some remarkable attributes that make them appealing for corrosion prevention applications. For example, Al-based glasses are resistant to pitting corrosion and can function as a corrosion barrier film, a sacrificial anode, and provide active corrosion inhibition by releasing alloying elements as inhibiting ions. While the amorphous structure makes these functions possible by allowing a high alloying element content to be achieved in solid solution, it is also a potential weakness because the amorphous structure is metastable. Partial crystallization occurs over time as nanometer-scale, solute-depleted f.c.c. Al precipitates ("nanocrystals") nucleate and grow within a remaining amorphous matrix. There was once some concern that these nanocrystals may serve as pit initiation sites and degrade the good pitting resistance of an amorphous alloy. Contrary to early predictions, this work shows that several partially nanocrystalline Al-based alloys are as corrosion resistant as fully amorphous alloys of the same bulk composition. This thesis provides an in-depth investigation of several mechanisms that can explain the good corrosion resistance of partially nanocrystalline glasses. The corrosion resistance of the amorphous and partially nanocrystalline glasses was first characterized by examining chloride induced pitting. The results of these experiments guided diagnostic studies of chloride-induced metastable pitting and stable pit growth, alkaline dissolution and passivation behavior, and surface characterization using SEM, TEM, and AFM, all at a sensitivity level tailored to detect nm-scale corrosion processes. These techniques together served as diagnostics to help determine the mechanism by which the corrosion resistance of a partially nanocrystalline Al-based glass may be similar or superior to that of its fully amorphous precursor. The overall conclusion of this dissertation is that Al-based glassy alloys with solute

  4. High metal reactivity and environmental risks at a site contaminated by glass waste.

    Science.gov (United States)

    Augustsson, A; Åström, M; Bergbäck, B; Elert, M; Höglund, L O; Kleja, D B

    2016-07-01

    This study addresses the reactivity and risks of metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, As and Sb) at a Swedish site with large glass waste deposits. Old glassworks sites typically have high total metal concentrations, but as the metals are mainly bound within the glass waste and considered relatively inert, environmental investigations at these kinds of sites are limited. In this study, soil and landfill samples were subjected to a sequential chemical extraction procedure. Data from batch leaching tests and groundwater upstream and downstream of the waste deposits were also interpreted. The sequential extraction revealed that metals in metals are released from pristine glass and subsequently largely retained in the surrounding soil and/or on secondary mineral coatings on fine glass particles. From the approximately 12,000 m(3) of coarse glass waste at the site, almost 4000 kg of Pb is estimated to have been lost through corrosion, which, however, corresponds to only a small portion of the total amount of Pb in the waste. Metal sorption within the waste deposits or in underlying soil layers is supported by fairly low metal concentrations in groundwater. However, elevated concentrations in downstream groundwater and in leachates of batch leaching tests were observed for several metals, indicating on-going leaching. Taken together, the high metal concentrations in geochemically active forms and the high amounts of as yet uncorroded metal-rich glass, indicate considerable risks to human health and the environment.

  5. Rapid Finite Element Analysis of Bulk Metal Forming Process Based on Deformation Theory

    Institute of Scientific and Technical Information of China (English)

    WANG Peng; DONG Xiang-huai; FU Li-jun

    2009-01-01

    The one-step finite element method (FEM), based on plastic deformation theory, has been widely used to simulate sheet metal forming processes, but its application in bulk metal forming simulation has been seldom investigated, because of the complexity involved. Thus, a bulk metal forming process was analyzed using a rapid FEM based on deformation theory. The material was assumed to be rigid-plastic and strain-hardened. The constitutive relationship between stress and total strain was adopted, whereas the incompressible condition was enforced by penalty function. The geometrical non-linearity in large plastic deformation was taken into consideration. Furthermore, the force boundary condition was treated by a simplified equivalent approach, considering the contact history. Based on constraint variational principle, the deformation FEM was proposed. The one-step forward simulation of axisymmetric upsetting process was performed using this method. The results were compared with those obtained by the traditional incremental FEM to verify the feasibility of the proposed method.

  6. Multifunctional methacrylate-based coatings for glass and metal surfaces

    Science.gov (United States)

    Pospiech, Doris; Jehnichen, Dieter; Starke, Sandra; Müller, Felix; Bünker, Tobias; Wollenberg, Anne; Häußler, Liane; Simon, Frank; Grundke, Karina; Oertel, Ulrich; Opitz, Michael; Kruspe, Rainer

    2017-03-01

    In order to prevent freshwater biofouling glass and metal surfaces were coated with novel transparent methacrylate-based copolymers. The multifunctionality of the copolymers, such as adhesion to the substrate, surface polarity, mechanical long-term stability in water, and ability to form metal complexes was inserted by the choice of suitable comonomers. The monomer 2-acetoacetoxy ethyl methacrylate (AAMA) was used as complexing unit to produce copper(II) complexes in the coating's upper surface layer. The semifluorinated monomer 1H,1H,2H,2H-perfluorodecyl methacrylate was employed to adjust the surface polarity and wettability. Comprehensive surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surface compositions and properties can be easily adjusted by varying the concentrations of the comonomers. The formation of copper(II) complexes along the copolymer chains and their stability against washing out with plenty of water was proven by XPS. Copolymers containing semifluorinated comonomers significantly inhibited the growth of Achnanthidium species. Copolymers with copper-loaded AAMA-sequences were able to reduce both the growth of Achnanthidium spec. and Staphylococcus aureus.

  7. 16 CFR 1500.49 - Technical requirements for determining a sharp metal or glass edge in toys and other articles...

    Science.gov (United States)

    2010-01-01

    ... sharp metal or glass edge in toys and other articles intended for use by children under 8 years of age... § 1500.49 Technical requirements for determining a sharp metal or glass edge in toys and other articles... metal or glass edges on toys and other articles intended for use by children under 8 years of age,...

  8. Glass surface metal deposition with high-power femtosecond fiber laser

    Science.gov (United States)

    Liu, Jian; Deng, Cheng; Bai, Shuang

    2016-12-01

    Using femtosecond fiber laser-based additive manufacturing (AM), metal powder is deposited on glass surface for the first time to change its surface reflection and diffuse its transmission beam. The challenge, due to mismatch between metal and glass on melting temperature, thermal expansion coefficient, brittleness, is resolved by controlling AM parameters such as power, scan speed, hatching, and powder thickness. Metal powder such as iron is successfully deposited and demonstrated functions such as diffusion of light and blackening effects.

  9. Large-Scale Manufacturing of Bulk Metallic Glass Sheets and Fiber Metal Laminates Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Liquidmetal Technologies (LMT) and the University of Southern California (USC)'s M.C. Gill Composites Center team up to develop manufacturing processes for...

  10. Electronic hybridisation implications for the damage-tolerance of thin film metallic glasses

    Science.gov (United States)

    Schnabel, Volker; Jaya, B. Nagamani; Köhler, Mathias; Music, Denis; Kirchlechner, Christoph; Dehm, Gerhard; Raabe, Dierk; Schneider, Jochen M.

    2016-01-01

    A paramount challenge in materials science is to design damage-tolerant glasses. Poisson’s ratio is commonly used as a criterion to gauge the brittle-ductile transition in glasses. However, our data, as well as results in the literature, are in conflict with the concept of Poisson’s ratio serving as a universal parameter for fracture energy. Here, we identify the electronic structure fingerprint associated with damage tolerance in thin film metallic glasses. Our correlative theoretical and experimental data reveal that the fraction of bonds stemming from hybridised states compared to the overall bonding can be associated with damage tolerance in thin film metallic glasses. PMID:27819318

  11. Observation of/β-Relaxation in Sub-Tg Isothermally Annealed A1-Based Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    YANG Hong-Wang; TONG Wei-Ping; ZHAO Xiang; ZUO Liang; WANG Jian-Qiang

    2008-01-01

    AlssNi5 Y8 Co2 and Al85Ni5 Y6 Co2Fe2 metallic glasses are fabricated by melt spinning. A kink or a small exothermic peak is observed for both the samples isothermally annealed at sub-glass transition temperatures. Temperature modulated differential scanning calorimetry (TMDSC) data disapprove amorphous phase separation. The activation energies derived from Kissinger plots of the exothermic process on DSC curve around glass transition temperature are consistent with those of β-relaxation of metallic glasses.

  12. Resistance to He2+ irradiation damage in metallic glass Ta38Ni62

    Science.gov (United States)

    Hou, Wenjing; Mei, Xianxiu; Zhang, Xiaonan; Wang, Yingmin; Qiang, Jianbing; Sun, Jianrong; Wang, Younian

    2016-10-01

    Metallic glass Ta38Ni62 strips, metallic W, and V87.5Cr4.17Ti4.17Nb4.17 alloy were irradiated using a 500 keV He2+ ion beam at different fluence to compare the metallic glass resistance to irradiation. Metallic glass Ta38Ni62 remained amorphous at different He2+ irradiation fluence. Transmission electron microscopy analysis revealed the presence of helium bubbles at the end of the range of helium ions in the metallic glass. No significant damage resulted in the metallic glass surface, and the root mean square roughness increased nonlinearly with the increase in fluence. At 1 × 1018 ions/cm2, metallic W appeared in larger sunken areas on the surface and V87.5Cr4.17Ti4.17Nb4.17 alloy experienced multi-layer flaking. The metallic glass Ta38Ni62 resistance to He2+ ion beam irradiation was better than that of metallic W, and that of the V87.5Cr4.17Ti4.17Nb4.17 alloy was the poorest.

  13. Introduction to the Growth of Bulk Single Crystals of Two-Dimensional Transition-Metal Dichalcogenides

    Science.gov (United States)

    Ueno, Keiji

    2015-12-01

    Semiconducting two-dimensional transition-metal dichalcogenides (MX2) are attracting much attention as promising materials for a new generation of optical and electronic devices. MX2 compounds are complementary or competitive to graphene because of the existence of a native band gap. The growth of large and high-quality bulk single crystals is one of the critical issues for the application of MX2 compounds, whose bulk crystals are generally grown by the chemical vapor transport (CVT) method. In the present review, I introduce experimental techniques required for the CVT growth of high-quality MX2 single crystals.

  14. Bulk and surface half-metallicity: The case of D03-type Mn3Ge

    Science.gov (United States)

    Liu, Hao; Gao, G. Y.; Hu, Lei; Ni, Yun; Zu, Fengxia; Zhu, Sicong; Wang, Shuling; Yao, K. L.

    2014-01-01

    Motivated by the experimental realization of D022-type Mn3Ge (001) films [Kurt et al. Appl. Phys. Lett. 101, 132410 (2012)] and the structural stability of D03-type Heusler alloy Mn3Ge [Zhang et al. J. Phys.: Condens. Matter 25, 206006 (2013)], we use the first-principles calculations based on the full potential linearized augmented plane-wave method to investigate the electronic and magnetic properties of D03-type Heusler alloy Mn3Ge and its (001) surface. We show that bulk D03-Mn3Ge is a half-metallic ferromagnet with the minority-spin energy gap of 0.52 eV and the magnetic moment of 1.00 μB per formula unit. The bulk half-metallicity is preserved at the pure Mn-terminated (001) surface due to the large exchange split, but the MnGe-terminated (001) surface destroys the bulk half-metallicity. We also reveal that the surface stabilities are comparable between the D03-Mn3Ge (001) and the experimental D022-Mn3Ge (001), which indicates the feasibility to grow the Mn3Ge (001) films with D03 phase other than D022 one. The surface half-metallicity and stability make D03-Mn3Ge a promising candidate for spintronic applications.

  15. OPTICALLY HOMOGENEOUS PHOSPHATE GLASSES DOPED WITH METAL NANOPARTICLES

    OpenAIRE

    Shakhgil'dyan, Georgiy; Savinkov, Vitaliy; Konev, Denis; Paleari, A.; Sigaev, Vladimir

    2013-01-01

    The technique of batch preparation, melting, glass working and nanoscale modification of the structure of phosphate glass doped with gold nanoparticles was developed. Glass samples containing different amounts of phosphorus oxide were synthesized. Heat treatments of the samples were held in a gradient furnace. Physical, spectral-luminescent and nonlinear optical properties of the samples were studied.

  16. Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites

    Science.gov (United States)

    Khanolkar, Gauri R.; Rauls, Michael B.; Kelly, James P.; Graeve, Olivia A.; Hodge, Andrea M.; Eliasson, Veronica

    2016-03-01

    The response of amorphous steels to shock wave compression has been explored for the first time. Further, the effect of partial devitrification on the shock response of bulk metallic glasses is examined by conducting experiments on two iron-based in situ metallic glass matrix composites, containing varying amounts of crystalline precipitates, both with initial composition Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4. The samples, designated SAM2X5-600 and SAM2X5-630, are X-ray amorphous and partially crystalline, respectively, due to differences in sintering parameters during sample preparation. Shock response is determined by making velocity measurements using interferometry techniques at the rear free surface of the samples, which have been subjected to impact from a high-velocity projectile launched from a powder gun. Experiments have yielded results indicating a Hugoniot Elastic Limit (HEL) to be 8.58 ± 0.53 GPa for SAM2X5-600 and 11.76 ± 1.26 GPa for SAM2X5-630. The latter HEL result is higher than elastic limits for any BMG reported in the literature thus far. SAM2X5-600 catastrophically loses post-yield strength whereas SAM2X5-630, while showing some strain-softening, retains strength beyond the HEL. The presence of crystallinity within the amorphous matrix is thus seen to significantly aid in strengthening the material as well as preserving material strength beyond yielding.

  17. New cellular metals with enhanced energy absorption: Wire-woven bulk kagome (WBK)-metal hollow sphere (MHS) hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming-Zhen; Kang, Ki-Ju [Department of Mechanical Systems Engineering, Chonnam National University, Kwangju (Korea, Republic of); Stephani, Guenter [Fraunhofer Institute for Manufacturing and Advanced Materials, Dresden (Germany)

    2011-02-15

    Two types of new cellular metals are fabricated by assembling layer by layer helically-formed wires with metal hollow sphere (MHS) arrays. In the finished configuration, the MHSs are located in small tetrahedrons or octahedrons of the inner space of a wire-woven bulk Kagome (WBK) structure. Compression tests reveal excellent energy absorption, which is attributed to combination of suppression of strut buckling in the WBK and moving plastic hinge occurring in the MHSs. The WBK-MHS hybrids outperform competitors in deformation energy absorption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Effect of UV exposure on photochromic glasses doped with transition metal oxides

    Science.gov (United States)

    El-Zaiat, S. Y.; Medhat, M.; Omar, Mona F.; Shirif, Marwa A.

    2016-07-01

    Silver halide photochromic glasses doped with one of the transition metal oxides, (Ti O2) , (CoO) ,(Cr2 O3) are prepared using the melt quench technique. Glass samples are exposed to a UV source for 20 min. Spectral reflectance and transmittance at normal incidence of the prepared glasses are recorded before and after UV exposure with a double beam spectrophotometer in the spectral range 200-2500 nm. Dispersion parameters such as: single oscillator energy, dispersion energy and Abbe's number are deduced and compared. Absorption dispersion parameters, like optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter, are deduced for the different glass prepared. Reflection loss, molar refractivity and electronic polarizability are deduced and compared. The effect of UV light exposure of these glasses on transmittance, reflectance, the linear and the predicted nonlinear optical parameters are investigated and discussed for the three transition metals. Nonlinear parameters increase in the three glass samples after UV exposure.

  19. Microstructural, thermal and mechanical behavior of co-sputtered binary Zr–Cu thin film metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Apreutesei, M. [MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Steyer, P., E-mail: philippe.steyer@insa-lyon.fr [MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Joly-Pottuz, L. [MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Billard, A. [LERMPS-UTBM, Site de Montbéliard, 90010 Belfort Cédex (France); Qiao, J.; Cardinal, S. [MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Sanchette, F. [LASMIS-UTT, UMR CNRS 6279, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Pelletier, J.M.; Esnouf, C. [MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France)

    2014-06-30

    Bulk metallic glasses have attracted considerable attention over the last decades for their outstanding mechanical features (high strength, super-elasticity) and physico-chemical properties (corrosion resistance). Recently, some attempts to assign such original behavior from bulk materials to modified surfaces have been reported in the literature based on multicomponent alloys. In this paper we focused on the opportunity to form a metallic glass coating from the binary Zr–Cu system using a magnetron co-sputtering physical vapor deposition process. The composition of the films can be easily controlled by the relative intensities applied to both pure targets, which made possible the study of the whole Zr–Cu system (from 13.4 to 85.0 at.% Cu). The chemical composition of the films was obtained by energy dispersive X-ray spectroscopy, and their microstructure was characterized by scanning and transmission electron microscopy. The thermal stability of the films was deduced from an in situ X-ray diffraction analysis (from room temperature up to 600 °C) and correlated with the results of the differential scanning calorimetry technique. Their mechanical properties were determined by nanoindentation experiments. - Highlights: • We reported deposition of Zr-Cu thin film metallic glasses by co-sputtering • Films were XRD-amorphous in a wide composition range (33.3 – 85.0 at.% Cu) • Microstructure investigation revealed some local nanodomains • We examined the thermal stability by means of in situ X-ray diffraction • Nanoindentation was used to obtained mechanical properties of thin films.

  20. Towards understanding of heat effects in metallic glasses on the basis of macroscopic shear elasticity

    Science.gov (United States)

    Mitrofanov, Y. P.; Wang, D. P.; Makarov, A. S.; Wang, W. H.; Khonik, V. A.

    2016-03-01

    It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. The underlying physical reason can be understood as relaxation in the system of interstitialcy-type ”defects” (elastic dipoles) frozen-in from the melt upon glass production.

  1. Cerium doped heavy metal fluoride glasses, a possible alternative for electromagnetic calorimetry

    CERN Document Server

    Auffray, Etiennette; Dafinei, I; Fay, J; Lecoq, P; Mares, J A; Martini, M; Mazé, G; Meinardi, F; Moine, B; Nikl, M; Pédrini, C; Poulain, M; Schneegans, M; Tavernier, Stefaan; Vedda, A

    1996-01-01

    The article is an overview of the research activity performed in the framework of the Crystal Clear Collaboration to produce scintillating glasses. The manufacturing of heavy metal fluoride glasses doped with Ce3+ is discussed. The luminescence and scintillation characteristics as well as the radiation hardness properties are extensively studied in the case of Ce doped fluorohafnate , found to be the most convenient glass scintillator for high energy physics applications.

  2. Bulk Properties of Transition Metals: A Challenge for the Design of Universal Density Functionals.

    Science.gov (United States)

    Janthon, Patanachai; Luo, Sijie Andy; Kozlov, Sergey M; Viñes, Francesc; Limtrakul, Jumras; Truhlar, Donald G; Illas, Francesc

    2014-09-09

    Systematic evaluation of the accuracy of exchange-correlation functionals is essential to guide scientists in their choice of an optimal method for a given problem when using density functional theory. In this work, accuracy of one Generalized Gradient Approximation (GGA) functional, three meta-GGA functionals, one Nonseparable Gradient Approximation (NGA) functional, one meta-NGA, and three hybrid GGA functionals was evaluated for calculations of the closest interatomic distances, cohesive energies, and bulk moduli of all 3d, 4d, and 5d bulk transition metals that have face centered cubic (fcc), hexagonal closed packed (hcp), or body centered cubic (bcc) structures (a total of 27 cases). Our results show that including the extra elements of kinetic energy density and Hartree-Fock exchange energy density into gradient approximation density functionals does not usually improve them. Nevertheless, the accuracies of the Tao-Perdew-Staroverov-Scuseria (TPSS) and M06-L meta-GGAs and the MN12-L meta-NGA approach the accuracy of the Perdew-Burke-Ernzerhof (PBE) GGA, so usage of these functionals may be advisable for systems containing both solid-state transition metals and molecular species. The N12 NGA functional is also shown to be almost as accurate as PBE for bulk transition metals, and thus it could be a good choice for studies of catalysis given its proven good performance for molecular species.

  3. Influence of the Substrate on the Formation of Metallic Glass Coatings by Cold Gas Spraying

    Science.gov (United States)

    Henao, John; Concustell, Amadeu; Dosta, Sergi; Cinca, Núria; Cano, Irene G.; Guilemany, Josep M.

    2016-06-01

    Cold gas spray technology has been used to build up coatings of Fe-base metallic glass onto different metallic substrates. In this work, the effect of the substrate properties on the viscoplastic response of metallic glass particles during their impact has been studied. Thick coatings with high deposition efficiencies have been built-up in conditions of homogeneous flow on substrates such as Mild Steel AISI 1040, Stainless Steel 316L, Inconel 625, Aluminum 7075-T6, and Copper (99.9%). Properties of the substrate have been identified to play an important role in the viscoplastic response of the metallic glass particles at impact. Depending on the process gas conditions, the impact morphologies show not only inhomogeneous deformation but also homogeneous plastic flow despite the high strain rates, 108 to 109 s-1, involved in the technique. Interestingly, homogenous deformation of metallic glass particles is promoted depending on the hardness and the thermal diffusivity of the substrate and it is not exclusively a function of the kinetic energy and the temperature of the particle at impact. Coating formation is discussed in terms of fundamentals of dynamics of undercooled liquids, viscoplastic flow mechanisms of metallic glasses, and substrate properties. The findings presented in this work have been used to build up a detailed scheme of the deposition mechanism of metallic glass coatings by the cold gas spraying technology.

  4. Excellent capability in degrading azo dyes by MgZn-based metallic glass powders

    Science.gov (United States)

    Wang, Jun-Qiang; Liu, Yan-Hui; Chen, Ming-Wei; Louzguine-Luzgin, Dmitri V.; Inoue, Akihisa; Perepezko, John H.

    2012-05-01

    The lack of new functional applications for metallic glasses hampers further development of these fascinating materials. In this letter, we report for the first time that the MgZn-based metallic glass powders have excellent functional ability in degrading azo dyes which are typical organic water pollutants. Their azo dye degradation efficiency is about 1000 times higher than that of commercial crystalline Fe powders, and 20 times higher than the Mg-Zn alloy crystalline counterparts. The high Zn content in the amorphous Mg-based alloy enables a greater corrosion resistance in water and higher reaction efficiency with azo dye compared to crystalline Mg. Even under complex environmental conditions, the MgZn-based metallic glass powders retain high reaction efficiency. Our work opens up a new opportunity for functional applications of metallic glasses.

  5. Microscopic iron metal on glass and minerals - A tool for studying regolith maturity

    Science.gov (United States)

    Allen, C. C.; Morris, R. V.; Lauer, H. V., Jr.; Mckay, D. S.

    1993-01-01

    A novel method of producing mixtures of glass or minerals with iron metal is presented. A portion of the Fe(2+) in basaltic glass and minerals can be reduced to metal in a few hours at 1100 C and an oxygen fugacity well below the iron-wustite buffer. Part of the iron metals forms rounded submicrometer blebs on the surfaces and in some cases within the grains. A concentration of such blebs equivalent to 20-30 percent of a grain's surface area can totally dominate the reflectance spectra of basaltic glass, pyroxene, and olivine. The production of optically opaque iron metal blebs, combined with the decline in Fe(2+), affects the glass and mineral reflectance spectra in three ways: by lowering the overall reflectivity, reducing the spectral contrast of absorption features, and producing a continuum with a general rise in reflectivity toward longer wavelengths.

  6. Preparation of oxide glasses from metal alkoxides by sol-gel method

    Science.gov (United States)

    Kamiya, K.; Yoko, T.; Sakka, S.

    1987-01-01

    An investigation is carried out on the types of siloxane polymers produced in the course of the hydrolysis of silicon tetraethoxide, as well as the preparation of oxide glasses from metal alkoxides by the sol-gel method.

  7. Molecular weight dependence of surface flow near the bulk glass transition temperature

    Science.gov (United States)

    Chai, Yu; Salez, Thomas; Benzaquen, Michael; Raphael, Elie; Forrest, James A.

    2014-03-01

    We present the study on molecular weight dependent sub-Tg surface dynamics of polymer thin films by using the Nano-step experiment [McGraw et al. Soft Matter 7, 7832 (2011)]. By varying the molecular weight, we are able to probe the surface dynamics of the free surface below Tg with the polymer size comparable to the surface depth. In particular, we define and use a correlation function to compare measured and calculated profiles to analyze the transition from the bulk flow to flow restricted to the surface region. Surprisingly, even for the polymers with Mw = 22,000 surface flow is still observed below the bulk Tg value. A numerical simulation of random walk is used to find the fraction of polymer of which all of the polymer segments are located in the free surface region. The simulation results indicate that there are still a significant fraction of polymer molecules where all segments are in the near free surface region. These molecules can undergo flow consistent with the experimental results.

  8. Microfabrication with femtosecond laser processing : (A) laser ablation of ferrous alloys, (B) direct-write embedded optical waveguides and integrated optics in bulk glasses.

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Junpeng; McDaniel, Karen Lynn; Palmer, Jeremy Andrew; Yang, Pin; Griffith, Michelle Lynn; Vawter, Gregory Allen; Harris, Marc F.; Tallant, David Robert; Luk, Ting Shan; Burns, George Robert

    2004-11-01

    -write optical waveguides and integrated optics in bulk glass. The effects of laser and environmental parameters on such aspects as removal rate, feature size, feature definition, and ablation angle during the ablation process of metals were studied. In addition, the manufacturing requirements for component fabrication including precision and reproducibility were investigated. The effect of laser processing conditions on the optical properties of direct-written waveguides and an unusual laser-induced birefringence in an optically isotropic glass are reported. Several integrated optical devices, including a Y coupler, directional coupler, and Mach-Zehnder interferometer, were made to demonstrate the simplicity and flexibility of this technique in comparison to the conventional waveguide fabrication processes.

  9. Bonding of metal oxides in sodium silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Lam, D.J.; Veal, B.W.; Chen, H.; Knapp, G.S.

    1978-01-01

    X-ray photoelectron spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) studies have been undertaken on sodium disilicate glasses containing varying amounts of Fe/sub 2/O/sub 3/ and UO/sub 2/. The XPS results enable one to distinguish the different bonding characteristics of iron and uranium in these glasses. A three dimensional model for the iron coordination in the sodium disilicate glass is inferred from the combined XPS and EXAFS results.

  10. Enhanced optical properties of germanate and tellurite glasses containing metal or semiconductor nanoparticles

    OpenAIRE

    Cid Bartolomeu de Araujo; Diego Silvério da Silva; Thiago Alexandre Alves de Assumpção; Luciana Reyes Pires Kassab; Davinson Mariano da Silva

    2013-01-01

    Germanium- and tellurium-based glasses have been largely studied due to their recognized potential for photonics. In this paper, we review our recent studies that include the investigation of the Stokes and anti-Stokes photoluminescence (PL) in different glass systems containing metallic and semiconductor nanoparticles (NPs). In the case of the samples with metallic NPs, the enhanced PL was attributed to the increased local field on the rare-earth ions located in the proximity of the NPs and/...

  11. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    Science.gov (United States)

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100−xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  12. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films.

    Science.gov (United States)

    Burgess, J A J; Holt, C M B; Luber, E J; Fortin, D C; Popowich, G; Zahiri, B; Concepcion, P; Mitlin, D; Freeman, M R

    2016-08-08

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100-xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections.

  13. Effect of several surface treatments on the strength of a glass ceramic-to-metal seal

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, D P; Salerno, R F; Egleston, E E

    1982-02-10

    Test shells of Inconel 625, Inconel 718, 21-6-9 stainless steel, and Hastelloy, C-276 were plasma and/or chemically cleaned before sealing with a multi-component glass-ceramic-to-metal seal was evaluated using a hydrostatic burst test. The results show that plasma cleaning can be used to increase the hydrostatic burst strength and hermeticity of a glass ceramic-to-metal seal.

  14. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  15. Hybrid Glasses from Strong and Fragile Metal-Organic Framework Liquids

    DEFF Research Database (Denmark)

    Bennett, T.D.; Tan, J.C.; Yue, Yuanzheng

    2015-01-01

    Hybrid glasses connect the emerging field of metal-organic frameworks (MOFs) with the glass formation, amorphization and melting processes of these chemically versatile systems. Though inorganic zeolites collapse around the glass transition and melt at higher temperatures, the relationship between...... amorphization and melting has so far not been investigated. Here we show how heating MOFs of zeolitic topology first results in a low density ‘perfect’ glass, similar to those formed in ice, silicon and disaccharides. This order–order transition leads to a super-strong liquid of low fragility that dynamically...

  16. Measurement of local internal friction in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, H.; Büchsenschütz-Göbeler, M.; Luo, Y.; Samwer, K. [I. Physikalisches Institut, Georg-August Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Kumar, A. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Arnold, W., E-mail: w.arnold@mx.uni-saarland.de [I. Physikalisches Institut, Georg-August Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Department of Materials and Materials Technology, Saarland University, Campus D 2.2, D-66123 Saarbrücken (Germany)

    2014-04-07

    Atomic force acoustic microscopy (AFAM), an advanced scanning probe microscopy technique, has been used to measure local elastic properties with a spatial resolution given by the tip-sample contact radius. AFAM is based on inducing out-of-plane vibrations in the specimen. The vibrations are sensed by the AFM cantilever from by the photodiode signal when its tip is in contact with the material under test. To measure local damping, the inverse quality factor Q{sup −1} of the resonance curve is usually evaluated. Here, from the contact-resonance spectra obtained, we determine the real and imaginary part of the contact stiffness k* and from these two quantities the local damping factor Q{sub loc}{sup −1} is obtained which is proportional to the imaginary part γ of the contact stiffness. The evaluation of the data is based on the cantilever's mass distribution with damped flexural modes and not on an effective point-mass approximation for the cantilever’s motion. The given equation is simple to use and has been employed to study the local Q{sub loc}{sup −1} of amorphous PdCuSi metallic glass and its crystalline counterpart as a function of position of the AFM tip on the surface. The width of the distribution changes dramatically from the amorphous to the crystalline state as expected from the consequences of the potential-energy landscape picture. The center value of the distribution curve for Q{sub loc}{sup −1} coincides very well with published data, based on global ultrasonic or internal friction measurements. This is compared to Q{sub loc}{sup −1} measured in crystalline SrTiO{sub 3}, which exhibits a narrow distribution, as expected.

  17. A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

    Science.gov (United States)

    Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

    2015-03-01

    Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

  18. Pressure effect on crystallization kinetics in Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Xu, Y.S.

    2002-01-01

    Crystallization kinetics of a Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass in the supercooled liquid region have been investigated by performing in situ high-temperature and high-pressure x-ray diffraction measurements using synchrotron radiation. A pressure-time-temperature-transformation diagram, desc...

  19. Mechanical Relaxation of Metallic Glasses: An Overview of Experimental Data and Theoretical Models

    Directory of Open Access Journals (Sweden)

    Chaoren Liu

    2015-06-01

    Full Text Available Relaxation phenomena in glasses are a subject of utmost interest, as they are deeply connected with their structure and dynamics. From a theoretical point of view, mechanical relaxation allows one to get insight into the different atomic-scale processes taking place in the glassy state. Focusing on their possible applications, relaxation behavior influences the mechanical properties of metallic glasses. This paper reviews the present knowledge on mechanical relaxation of metallic glasses. The features of primary and secondary relaxations are reviewed. Experimental data in the time and frequency domain is presented, as well as the different models used to describe the measured relaxation spectra. Extended attention is paid to dynamic mechanical analysis, as it is the most important technique allowing one to access the mechanical relaxation behavior. Finally, the relevance of the relaxation behavior in the mechanical properties of metallic glasses is discussed.

  20. Symmetry foundations of a polymer model for close-packed metallic liquids and glasses

    Science.gov (United States)

    Kraposhin, V. S.; Talis, A. L.

    2016-02-01

    The atomic packing density of metallic melts and glasses is too high for their structures to be considered as chaotic. To remove this contradiction, we propose to describe the structures of metallic liquids and the glasses that form from them using (i) a base set of three spirals made of regular tetrahedra with specific noncrystallographic symmetry and (ii) combinatorial permutations of the vertices of a set of the coordination polyhedra that describe the polymorphic transformations in metals. The symmetry base of the proposed model of the structures of liquids and glasses is represented by projective linear groups PSL(2, p), where the order of the Galois field is p = 3, 7, and 11. These groups uniquely determine a tetrahedron, the 7-vertex joining of four tetrahedra along their faces (tetrablock), the 11-vertex joining of two tetrablocks into a spiral, and the throwing over of the diagonals in a rhombus from two triangular faces of neighboring tetrahedra. The throwing over of the diagonals in a rhombus is considered as a unit act of any structural transformation and ensures the melt-crystal, melt-glass, and glass-crystal transitions and the structural relaxation of metallic glasses. In terms of the proposed scheme, the high density of melts and glasses is caused by tetrahedral packing (up to 78%), and the absence of a diffraction pattern of melts and glasses is explained by the absence of translation along the spiral axis. The suggested polymer model also explains the collective effects (string vibrations) that were detected upon measuring the shear modulus relaxation of a metallic glass.

  1. Computation assisted design of favored composition for ternary Mg-Cu-Y metallic glass formation.

    Science.gov (United States)

    Wang, Q; Li, J H; Liu, B X

    2015-06-14

    With the aid of ab initio calculations, a realistic interatomic potential was constructed for the Mg-Cu-Y ternary system under the proposed formalism of smoothed and long-range second-moment approximation of tight-binding. Taking the potential as the starting base, an atomistic computation/simulation route was developed for designing favored and optimized compositions for Mg-Cu-Y metallic glass formation. Simulations revealed that the physical origin of metallic glass formation is the collapse of crystalline lattice when solute concentration exceeds a critical value, thus leading to predict a hexagonal region in the Mg-Cu-Y composition triangle, within which metallic glass formation is energetically favored. It is proposed that the hexagonal region can be defined as the intrinsic glass formation region, or quantitative glass formation ability of the system. Inside the hexagonal region, the driving force for formation of each specific glassy alloy was further calculated and correlated with its forming ability in practice. Calculations pinpointed the optimized stoichiometry in the Mg-Cu-Y system to be Mg64Cu16Y20, at which the formation driving force reaches its maximum, suggesting that metallic glasses designed to have compositions around Mg64Cu16Y20 are most stable or easiest to obtain. The predictions derived directly from the atomistic simulations are supported by experimental observations reported so far in the literature. Furthermore, Honeycutt-Anderson analysis indicated that pentagonal bipyramids (although not aggregating to form icosahedra) dominate in the local structure of the Mg-Cu-Y metallic glasses. A microscopic picture of the medium-range packing can then be described as an extended network of the pentagonal bipyramids, entangled with the fourfold and sixfold disclination lines, jointly fulfilling the space of the metallic glasses.

  2. Effect of nanosecond pulse laser ablation on the surface morphology of Zr-based metallic glass

    Science.gov (United States)

    Zhu, Yunhu; Fu, Jie; Zheng, Chao; Ji, Zhong

    2016-09-01

    In this study, we investigated the ripple patterns formation on the surface of Zr41.2Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk metallic glass using a nanosecond pulse laser ablation in air with a wavelength of 1064 nm. The strong thermal ablation phenomenon could be observed on vit1 BMG surface at laser energy of 200 mJ as a result of the adhibition of confining overlay. Many periodic ripples had formed on the edge of the ablated area at laser energy of 400 mJ because of the high intensity pulsed laser beam. The underlying mechanism of the periodic ripples formation could be explained by the K-H hydrodynamic instability theory. It had been shown that laser ablation with 600 mJ and 200 pulses results in the formation of many micro-cracks on the ablated area. Further analysis showed that the spatial occupation of the laser ablated area and the spacing between two adjacent ripples increased as the laser energy and the number of incident laser pulses increasing. The surface ripples feature on the edge of ablated area became more obvious with increasing laser pulses, but it was not correlated closely with the laser energies variation.

  3. Crack-tip strain field mapping and the toughness of metallic glasses.

    Directory of Open Access Journals (Sweden)

    Todd C Hufnagel

    Full Text Available We have used high-energy x-ray scattering to map the strain fields around crack tips in fracture specimens of a bulk metallic glass under load at room temperature and below. From the measured strain fields we can calculate the components of the stress tensor as a function of position and determine the size and shape of the plastic process zone around the crack tip. Specimens tested at room temperature develop substantial plastic zones and achieve high stress intensities ((K(If = 76 MPa m(1/2 prior to fracture. Specimens tested at cryogenic temperatures fail at reduced but still substantial stress intensities (K(If = 39 MPa m(1/2 and show only limited evidence of crack-tip plasticity. We propose that the difference in behavior is associated with changes in the flow stress and elastic constants, which influence the number density of shear bands in the plastic zone and thus the strain required to initiate fracture on an individual band. A secondary effect is a change in the triaxial state of stress around the crack tip due to the temperature dependence of Poisson's ratio. It is likely that this ability to map elastic strains on the microscale will be useful in other contexts, although interpreting shifts in the position of the scattering peaks in amorphous materials in terms of elastic strains must be done with caution.

  4. Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

    Science.gov (United States)

    He, Jie; Kaban, Ivan; Mattern, Norbert; Song, Kaikai; Sun, Baoan; Zhao, Jiuzhou; Kim, Do Hyang; Eckert, Jürgen; Greer, A. Lindsay

    2016-01-01

    At room temperature, plastic flow of metallic glasses (MGs) is sharply localized in shear bands, which are a key feature of the plastic deformation in MGs. Despite their clear importance and decades of study, the conditions for formation of shear bands, their structural evolution and multiplication mechanism are still under debate. In this work, we investigate the local conditions at shear bands in new phase-separated bulk MGs containing glassy nanospheres and exhibiting exceptional plasticity under compression. It is found that the glassy nanospheres within the shear band dissolve through mechanical mixing driven by the sharp strain localization there, while those nearby in the matrix coarsen by Ostwald ripening due to the increased atomic mobility. The experimental evidence demonstrates that there exists an affected zone around the shear band. This zone may arise from low-strain plastic deformation in the matrix between the bands. These results suggest that measured property changes originate not only from the shear bands themselves, but also from the affected zones in the adjacent matrix. This work sheds light on direct visualization of deformation-related effects, in particular increased atomic mobility, in the region around shear bands. PMID:27181922

  5. On the induction of homogeneous bulk crystallization in Eu-doped calcium aluminosilicate glass by applying simultaneous high pressure and temperature

    Science.gov (United States)

    Muniz, R. F.; de Ligny, D.; Le Floch, S.; Martinet, C.; Rohling, J. H.; Medina, A. N.; Sandrini, M.; Andrade, L. H. C.; Lima, S. M.; Baesso, M. L.; Guyot, Y.

    2016-06-01

    From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca3Mg(SiO4)2] and diopside [CaMgSi2O6]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f65d1 → 4f7 transition of Eu2+ was studied in both host systems. Additionally, the 5D0 → 7FJ transition of Eu3+ was used as an environment probe in the pristine glass and the glass-ceramic.

  6. Preparation of high density heavy metal fluoride glasses with extended ultraviolet and infra red ranges, and such high density heavy metal fluoride glasses

    Science.gov (United States)

    Martin, Steven W. (Inventor); Huebsch, Jesse (Inventor)

    2001-01-01

    A heavy metal fluoride glass composition range (in mol percent) consisting essentially of: (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24)InF.sub.3 or GaF.sub.3.(4-16)CdF.sub.2.(6-24)YbF.sub.3.(4-22)ZnF.sub.2. In an alternative embodiment, a heavy metal fluoride glass composition range (in mol percent) comprises (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24) of (0-24)InF.sub.3, (0-24)GaF.sub.3 and (0-19)AlF.sub.3.(1-16)CdF.sub.2.(6-24)YbF.sub.3.(4-26)ZnF.sub.2. A preferred heavy metal fluoride glass produced in accordance with the present invention comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.7InF.sub.3.5GaF.sub.3.10CdF.sub.2.18YbF.sub.3. 16ZnF.sub.2. A preferred heavy metal fluoride glass has maximum thickness of most preferably about 3 mm. Another preferred heavy metal fluoride glass comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.12AlF.sub.3.10CdF.sub.2.18YbF.sub.3.16ZnF.sub.2.

  7. Thermodynamic prediction of glass formation tendency, cluster-in-jellium model for metallic glasses, ab initio tight-binding calculations, and new density functional theory development for systems with strong electron correlation

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yongxin [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Solidification of liquid is a very rich and complicated field, although there is always a famous homogeneous nucleation theory in a standard physics or materials science text book. Depending on the material and processing condition, liquid may solidify to single crystalline, polycrystalline with different texture, quasi-crystalline, amorphous solid or glass (Glass is a kind of amorphous solid in general, which has short-range and medium-range order). Traditional oxide glass may easily be formed since the covalent directional bonded network is apt to be disturbed. In other words, the energy landcape of the oxide glass is so complicated that system need extremely long time to explore the whole configuration space. On the other hand, metallic liquid usually crystalize upon cooling because of the metallic bonding nature. However, Klement et.al., (1960) reported that Au-Si liquid underwent an amorphous or “glassy” phase transformation with rapid quenching. In recent two decades, bulk metallic glasses have also been found in several multicomponent alloys[Inoue et al., (2002)]. Both thermodynamic factors (e.g., free energy of various competitive phase, interfacial free energy, free energy of local clusters, etc.) and kinetic factors (e.g., long range mass transport, local atomic position rearrangement, etc.) play important roles in the metallic glass formation process. Metallic glass is fundamentally different from nanocrystalline alloys. Metallic glasses have to undergo a nucleation process upon heating in order to crystallize. Thus the short-range and medium-range order of metallic glasses have to be completely different from crystal. Hence a method to calculate the energetics of different local clusters in the undercooled liquid or glasses become important to set up a statistic model to describe metalllic glass formation. Scattering techniques like x-ray and neutron have widely been used to study the structues of metallic glasses. Meanwhile, computer simulation

  8. Optical properties of dy doped lead and bismuth borate glasses - effect of glass composition, metal and semiconducting nanoparticles

    Science.gov (United States)

    Ooi, Hio Giap

    The optical properties of Dy3+ ions in lead borate and bismuth borate glasses are studied as a function of glass composition with PbO content (29.5 to 69.5mol%) and Bi2O3 content (29.5 to 59.5 mol%). We also studied the effect of metal and semiconducting nanoparticles on the absorption and fluorescence emission of Dy3+ ions in both lead and bismuth borate glasses. The absorption coefficient at each wavelength is obtained from the optical absorption spectrum of a glass sample, and the number density of rare-earth (RE) ions is calculated from the measurement of the glass density. These two parameters are then used to calculate the oscillator strength of each transition using Judd-Ofelt theory. Using the oscillator strength for each transition, we obtained the intensity parameters which represent changes in the symmetry of the ligand field at the Dy 3+ site (due to structural group changes and changes in Dy-O covalency). Radiative transition probabilities, the radiative lifetime of the excited states and the branching ratios are then obtained from these intensity parameters. The fluorescence spectra, obtained using 355 nm and 458 nm laser excitation, are analyzed by determining the area ratio of yellow/blue (Y/B) peaks and the wavelength of the hypersensitive transition (HST). The compositional dependence and effect of nanoparticles on the stimulated emission cross-section (sigmap), are then evaluated using radiative transition probability, the refractive index of the host glass, effective fluorescence linewidth, and the position of the band. In all of the glass systems, it was found that the optical properties are strongly influenced by structural changes arising from compositional variation and size of nanoparticles. Dy 3+ transitions exhibit large sigmap suggesting the possible utilization of these materials in laser applications.

  9. Bulk and surface electromagnetic response of metallic metamaterials to convection electrons

    Science.gov (United States)

    So, Jin-Kyu; Jang, Kyu-Ha; Park, Gun-Sik; Garcia-Vidal, F. J.

    2011-08-01

    The electromagnetic response of three-dimensional metallic metamaterials with isotropic effective index of refraction to fast-moving electrons is studied by numerical simulations. The considered metamaterials can support Cerenkov radiation [P. A. Cherenkov, Dokl. Akad. Nauk SSSR 2, 451 (1934)], and their effective dielectric behavior is confirmed by the detailed angular dependence of the generated radiation cone on the kinetic energy of electrons. Moreover, in addition to the predicted bulk modes, surface electromagnetic excitation is observed in a specific type of metamaterials and its dispersion is sensitive to the thickness of the subwavelength rods.

  10. Non-Isothermal Kinetic Analysis of the Crystallization of Metallic Glasses Using the Master Curve Method

    OpenAIRE

    Jürgen Eckert; Stefan Roth; Joan Torrens-Serra; Mihai Stoica; Uta Kuehn; Shankar Venkataraman

    2011-01-01

    The non-isothermal transformation rate curves of metallic glasses are analyzed with the Master Curve method grounded in the Kolmogorov-Johnson-Mehl-Avrami theory. The method is applied to the study of two different metallic glasses determining the activation energy of the transformation and the experimental kinetic function that is analyzed using Avrami kinetics. The analysis of the crystallization of Cu47Ti33Zr11Ni8Si1 metallic glassy powders gives Ea = 3.8 eV, in good agreement with the cal...

  11. Electrofluidics fabricated by space-selective metallization in glass microfluidic structures using femtosecond laser direct writing.

    Science.gov (United States)

    Xu, Jian; Wu, Dong; Hanada, Yasutaka; Chen, Chi; Wu, Sizhu; Cheng, Ya; Sugioka, Koji; Midorikawa, Katsumi

    2013-12-07

    Space-selective metallization of the inside of glass microfluidic structures using femtosecond laser direct-write ablation followed by electroless plating is demonstrated. Femtosecond laser direct writing followed by thermal treatment and successive chemical etching allows us to fabricate three-dimensional microfluidic structures inside photosensitive glass. Then, femtosecond laser ablation followed by electroless metal plating enables flexible deposition of patterned metal films on desired locations of not only the top and bottom walls but also the sidewalls of fabricated microfluidic structures. A volume writing scheme for femtosecond laser irradiation inducing homogeneous ablation on the sidewalls of microfluidic structures is proposed for sidewall metallization. The developed technique is used to fabricate electrofluidics in which microelectric components are integrated into glass microchannels. The fabricated electrofluidics are applied to control the temperature of liquid samples in the microchannels for the enhancement of chemical reactions and to manipulate the movement of biological samples in the microscale space.

  12. Remarkably stable amorphous metal oxide grown on Zr-Cu-Be metallic glass.

    Science.gov (United States)

    Lim, Ka Ram; Kim, Chang Eun; Yun, Young Su; Kim, Won Tae; Soon, Aloysius; Kim, Do Hyang

    2015-12-14

    In the present study, we investigated the role of an aliovalent dopant upon stabilizing the amorphous oxide film. We added beryllium into the Zr50Cu50 metallic glass system, and found that the amorphous oxide layer of Be-rich phase can be stabilized even at elevated temperature above Tg of the glass matrix. The thermal stability of the amorphous oxide layer is substantially enhanced due to Be addition. As confirmed by high-temperature cross-section HR-TEM, fully disordered Be-added amorphous layer is observed, while the rapid crystallization is observed without Be. To understand the role of Be, we employed ab-initio molecular dynamics to compare the mobility of ions with/without Be dopant, and propose a disordered model where Be dopant occupies Zr vacancy and induces structural disorder to the amorphous phase. We find that the oxygen mobility is slightly suppressed due to Be dopant, and Be mobility is unexpectedly lower than that of oxygen, which we attribute to the aliovalent nature of Be dopant whose diffusion always accompany multiple counter-diffusion of other ions. Here, we explain the origin of superior thermal stability of amorphous oxide film in terms of enhanced structural disorder and suppressed ionic mobility due to the aliovalent dopant.

  13. Advanced finite element analysis of die wear in sheet-bulk metal forming processes

    Science.gov (United States)

    Behrens, Bernd-Arno; Bouguecha, Anas; Vucetic, Milan; Chugreev, Alexander; Rosenbusch, Daniel

    2016-10-01

    The novel sheet-bulk metal forming (SBMF) technology allows the production of solid metal components with various functional design features out of flat sheet specimens. However, due to the high working pressures arising during the forming process the efficiency of SBMF is tightly related to the tool service life, which is mainly limited by die wear. In the forming processes involving high contact pressures (e.g. SBMF) the influence of contact normal stresses on the die wear can be overestimated. In order to provide a realistic estimation of the die wear, the shear friction stress must be considered. The presented paper introduces a die wear model that intends the tangential component of contact stress and its implementation in the commercial FE code.

  14. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    Science.gov (United States)

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-04-12

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  15. Chemical short-range order domain in bulk amorphous alloy and the prediction of glass forming ability

    Institute of Scientific and Technical Information of China (English)

    HUI; Xidong(惠希东); YAO; Kefu(姚可夫); KOU; Hongchao(寇宏超); CHEN; Guoliang(陈国良)

    2003-01-01

    Short-range order domains of face central cubic Zr2Ni (F-Zr2Ni) and tetragonal Zr2Ni (T-Zr2Ni) type structure with a size about 1-3 nanometers were observed in bulk amorphous Zr52.5Cu17.9Ni14.6Al10Ti5 alloy by using HREM and nano-beam electron diffraction technique. A new thermodynamic model was formulated based on the concept of chemical short-range order (SCRO). The molar fractions of CSRO and thermodynamic properties in Ni-Zr, Cu-Zr, Al-Zr, Al-Ni, Zr-Ni-Al and Zr-Ni-Cu were calculated. According to the principle of maximum the optimum glass forming ability (GFA) compositions were predicted in binary and ternary alloys. These results were proved to be valid by the experimental data of crystallizing activation energy, ΔTx and XRD patterns. The TTT curves of Zr-Ni-Cu alloys calculated based on CSRO model shows that the lowest critical cooling rate GFA is in the order of 100 K/s, which is close to the practical cooling rate for the preparation of Zr-based BMG alloys.

  16. Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels

    Directory of Open Access Journals (Sweden)

    Subramanian B

    2015-10-01

    Full Text Available Balasubramanian Subramanian,1 Sundaram Maruthamuthu,2 Senthilperumal Thanka Rajan1 1Electrochemical Material Science Division, 2Corrosion and Materials Protection Division, Central Electrochemical Research Institute, Karaikudi, India Abstract: Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.% of approximately 1.5 µm and 3 µm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature. Keywords: thin film metallic glasses, sputtering, biocompatibility, corrosion, antimicrobial activity

  17. Micro-mechanical behavior of porous tungsten/Zr-based metallic glass composite under cyclic compression

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.Q. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xue, Y.F., E-mail: xueyunfei@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wang, L.; Fan, Q.B.; Nie, Z.H. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zhang, H.F.; Fu, H.M. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-09-03

    The micro-mechanical behavior of porous tungsten/Zr-based metallic glass composites with different tungsten volume fraction was investigated under cyclic compression by synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) and finite element modeling (FEM). During cyclic compression, the dislocation in the tungsten phase tangled near the interfaces, indicating that the elastic metallic glass phase restricted dislocation motion and obstructed the deformation of the tungsten phase because of the heterogeneity in stress. After the metallic glass phase yielded, the dislocation tended to propagate away from the interfaces, showing the decrease of the interphase stress affected the direction of motion in the dislocations. The tungsten phase exhibited increased yield strength with the increase of cyclic loading number. Yield stress of the tungsten phase decreased with increasing the tungsten volume fraction during cyclic compression, which was influenced by the elastic strain mismatch between the two phases. The stress heterogeneity and the stress distribution difference between the two phases resulted in that the yield strength of the metallic glass phase decreased with the increase of tungsten volume fraction, and accelerated the formation of shear bands in the metallic glass phase as well as cracks in the tungsten phase. The heterogeneity in stress also excessed the interface bonding strength, inducing interface fracture near interfaces.

  18. Experimental design and process analysis for acidic leaching of metal-rich glass wastes.

    Science.gov (United States)

    Tuncuk, A; Ciftci, H; Akcil, A; Ognyanova, A; Vegliò, F

    2010-05-01

    The removal of iron, titanium and aluminium from colourless and green waste glasses has been studied under various experimental conditions in order to optimize the process parameters and to decrease the metal content in the waste glass by acidic leaching. Statistical design of experiments and ANOVA (analysis of variance) were performed in order to determine the main effects and interactions between the investigated factors (sample ratio, acid concentration, temperature and leaching time). A full factorial experiment was performed by sulphuric acid leaching of glass for metal removal. After treating, the iron content was 530 ppm, corresponding to 1880 ppm initial concentration of Fe(2)O(3) in the original colourless sample. This result is achieved using 1M H(2)SO( 4) and 30% sample ratio at 90(o)C leaching temperature for 2 hours. The iron content in the green waste glass sample was reduced from 3350 ppm initial concentration to 2470 ppm after treating.

  19. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Energy Technology Data Exchange (ETDEWEB)

    Gargarella, P., E-mail: piter@ufscar.br [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, 13565-905 São Carlos, São Paulo (Brazil); Pauly, S.; Stoica, M.; Kühn, U. [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Vaughan, G. [European Synchrotron Radiation Facilities, BP 220, 38043 Grenoble (France); Afonso, C. R. M. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, 13565-905 São Carlos, São Paulo (Brazil); Eckert, J. [IFW Dresden, Institut für Komplexe Materialien, Helmholtzstraße 20, D-01069 Dresden (Germany); Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01062 Dresden (Germany)

    2015-01-01

    The structural evolution of Ti{sub 50}Cu{sub 43}Ni{sub 7} and Ti{sub 55}Cu{sub 35}Ni{sub 10} metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  20. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Science.gov (United States)

    Gargarella, P.; Pauly, S.; Stoica, M.; Vaughan, G.; M. Afonso, C. R.; Kühn, U.; Eckert, J.

    2015-01-01

    The structural evolution of Ti50Cu43Ni7 and Ti55Cu35Ni10 metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  1. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    Directory of Open Access Journals (Sweden)

    P. Gargarella

    2015-01-01

    Full Text Available The structural evolution of Ti50Cu43Ni7 and Ti55Cu35Ni10 metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  2. Relationship between Compostion,Density and Refractive Index for Heavy Metal Fluoride Glasses

    Institute of Scientific and Technical Information of China (English)

    ShaukatS.F; HobsonP.R.; 等

    2001-01-01

    The density and the refractive index for various compositions of heavy metal fluoride(HMF) glasses,used to make low-loss optical wave-guides,have been measured by standard archimedes method and by using as Pulfrich refrctometer respectively.The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant.The refractive index as a function of composition is also calcuated.based on the Lorenz-Lorentz equation,by computing the electronic polarizability of HMF glasses.All calculated results are in good agreement with the observed data.

  3. Exposure Buildup Factors for Heavy Metal Oxide Glass: A Radiation Shield

    DEFF Research Database (Denmark)

    Manonara, S. R.; Hanagodimath, S. M.; Gerward, Leif;

    2011-01-01

    Gamma ray exposure buildup factors for three Heavy Metal Oxide (HMO) glass systems, viz. PbO-Bi2O3-B2O3, PbO-B2O3, and Bi2O3-B2O3 glasses are presented. The computations were done by interpolation method using the Geometric Progression fitting formula and ANSI/ANS-6.4.3 library for the energy ran...... of graphs. Buildup factors of these HMO glasses cannot be found in any standard database, but they are useful for practical calculations in gamma ray shield designs, and they also, help to determine and control the thickness of the shielding material used....

  4. Proposed Testing to Assess the Accuracy of Glass-To-Metal Seal Stress Analyses.

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, Robert S.; Emery, John M; Tandon, Rajan; Antoun, Bonnie R.; Stavig, Mark E.; Newton, Clay S.; Gibson, Cory S; Bencoe, Denise N.

    2014-09-01

    The material characterization tests conducted on 304L VAR stainless steel and Schott 8061 glass have provided higher fidelity data for calibration of material models used in Glass - T o - Metal (GTM) seal analyses. Specifically, a Thermo - Multi - Linear Elastic Plastic ( thermo - MLEP) material model has be en defined for S S304L and the Simplified Potential Energy Clock nonlinear visc oelastic model has been calibrated for the S8061 glass. To assess the accuracy of finite element stress analyses of GTM seals, a suite of tests are proposed to provide data for comparison to mo del predictions.

  5. A detailed study of metallic glass formation in copper-hafnium-titanium alloys

    Institute of Scientific and Technical Information of China (English)

    Ignacio A. Figueroa; Sandro Baez-Pimiento; John D. Plummer; Omar Novelo-Peralta; Hywell A. Davies; Iain Todd

    2012-01-01

    Recently we have reported a number of bulk glass forming compositions in the CuHf-Ti system,with the critical thickness for complete glass formation,dc1 ranging from 2 mm to 4 mm.In order to improve the glass forming ability (GFA) getting even larger dc1 the prevailing approach is to use complex multicomponent systems.This strategy has been investigated by us for the Cu-Hf-Ti bulk glass forming alloy Cu55Hf25Ti20 using >1 at.pct additions of B,Y,Nb,Ta,Al,Mn,Si or V but with no significant improvement in the GFA.Clearly,it is necessary,in order to utilise the full potential of the base ternary system,to identify the best glass-forming compositions as a basis for extending the search into multi-dimensional compositional space.Thus,CuxHfyTiz alloys,where x=(40-70) at.pct,y=(5-30) at.pct,and z=(10-36) at.pct,were prepared by melt spinning and copper mould suction-casting.The composition dependence of the GFA for the Cu-Hf-Ti alloys,as measured by dc for rod and ribbon samples,is reported over the composition range given above.

  6. Calcium and zinc containing bactericidal glass coatings for biomedical metallic substrates.

    Science.gov (United States)

    Esteban-Tejeda, Leticia; Díaz, Luis A; Prado, Catuxa; Cabal, Belén; Torrecillas, Ramón; Moya, José S

    2014-07-23

    The present work presents new bactericidal coatings, based on two families of non-toxic, antimicrobial glasses belonging to B2O3-SiO2-Na2O-ZnO and SiO2-Na2O-Al2O3-CaO-B2O3 systems. Free of cracking, single layer direct coatings on different biomedical metallic substrates (titanium alloy, Nb, Ta, and stainless steel) have been developed. Thermal expansion mismatch was adjusted by changing glass composition of the glass type, as well as the firing atmosphere (air or Ar) according to the biomedical metallic substrates. Formation of bubbles in some of the glassy coatings has been rationalized considering the reactions that take place at the different metal/coating interfaces. All the obtained coatings were proven to be strongly antibacterial versus Escherichia coli (>4 log).

  7. Calcium and Zinc Containing Bactericidal Glass Coatings for Biomedical Metallic Substrates

    Directory of Open Access Journals (Sweden)

    Leticia Esteban-Tejeda

    2014-07-01

    Full Text Available The present work presents new bactericidal coatings, based on two families of non-toxic, antimicrobial glasses belonging to B2O3–SiO2–Na2O–ZnO and SiO2–Na2O–Al2O3–CaO–B2O3 systems. Free of cracking, single layer direct coatings on different biomedical metallic substrates (titanium alloy, Nb, Ta, and stainless steel have been developed. Thermal expansion mismatch was adjusted by changing glass composition of the glass type, as well as the firing atmosphere (air or Ar according to the biomedical metallic substrates. Formation of bubbles in some of the glassy coatings has been rationalized considering the reactions that take place at the different metal/coating interfaces. All the obtained coatings were proven to be strongly antibacterial versus Escherichia coli (>4 log.

  8. Tensile behavior of laser treated Fe-Si-B metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Sameehan S.; Samimi, Peyman; Ghamarian, Iman; Katakam, Shravana; Collins, Peter C.; Dahotre, Narendra B., E-mail: narendra.dahotre@unt.edu [Department of Materials Science and Engineering, University of North Texas, 1150 Union Circle 305310, Denton, Texas 76203-5017 (United States)

    2015-10-28

    Fe-Si-B metallic glass foils were treated with a linear laser track using a continuous wave Nd-YAG laser and its effect on the overall tensile behavior was investigated. Microstructure and phase evolutions were evaluated using X-ray diffraction, resistivity measurements, and transmission electron microscopy. Crystallization fraction was estimated via the differential scanning calorimetry technique. Metallic glass foils treated with the lower laser fluences (<0.49 J/mm{sup 2}) experienced structural relaxation, whereas higher laser fluences led to crystallization within the laser treated region. The overall tensile behavior was least impacted by structural relaxation, whereas crystallization severely reduced the ultimate tensile strength of the laser treated metallic glass foils.

  9. Microstructure and Wear Behavior of FeBSiNbCr Metallic Glass Coatings

    Institute of Scientific and Technical Information of China (English)

    Jiangbo Cheng; Xiubing Liang; Binshi Xu; Yixiong Wu

    2009-01-01

    In this paper, FeBSiNbCr metallic glass coatings were prepared onto AISI 1045 steel substrate by using wire arc spraying process. The phase and structure of the coating were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning election microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX). The microstructure of the coating consists of full amorphous phase. The coating has high hardness and low porosity. Full density and little oxides are detected in the coating. The mechanical properties, especially wear resistance, were investigated. The relationship between wear behavior and structure of the coatings were analyzed in detail. The main failure mechanism of the metallic glass coating is brittle breaking and fracture. The results indicate that FeBSiNbCr metallic glass coating has excellent resistance to abrasive wear.

  10. Integration of robust fluidic interconnects using metal to glass anodic bonding

    Science.gov (United States)

    Briand, Danick; Weber, Patrick; de Rooij, Nicolaas F.

    2005-09-01

    This paper reports on the encapsulation of a piezoresistive silicon/Pyrex liquid flow sensor using metal to glass anodic bonding. The bonding technique allowed integrating robust metallic microfluidic interconnects and eliminating the use of glue and O-rings. The bonding parameters of a silicon/Pyrex/metal triple stack were chosen to minimize the residual stress and to obtain a strong and liquid tight bonding interface. The silicon/Pyrex liquid flow sensor was successfully bonded to metallic plates of Kovar and Alloy 42, on which tubes were fixed and a printed circuit board (PCB) was integrated. A post-bonding annealing procedure was developed to reduce the residual bonding stress. The characteristics of the encapsulated liquid flow sensor, such as the temperature coefficient of sensitivity, fulfilled the specifications. Wafer level packaging using metal to glass anodic bonding was considered to reduce the packaging size and cost.

  11. An electron microscopy appraisal of tensile fracture in metallic glasses

    NARCIS (Netherlands)

    Matthews, D. T. A.; Ocelik, V.; Bronsveld, P. M.; De Hosson, J. Th. M.

    2008-01-01

    Three glass-forming alloy compositions were chosen for ribbon production and subsequent electron microscopy studies. In situ tensile testing with transmission electron microscopy (TEM), followed by ex situ TEM and ex situ scanning electron microscopy (SEM), allowed the deformation processes in tensi

  12. Melt-quenched glasses of metal-organic frameworks

    DEFF Research Database (Denmark)

    Bennett, T.D.; Yue, Yuanzheng; Li, P.

    2016-01-01

    Crystalline solids dominate the field of metal−organic frameworks (MOFs), with access to the liquid and glass states of matter usually prohibited by relatively low temperatures of thermal decomposition. In this work, we give due consideration to framework chemistry and topology to expand the phen...

  13. Tensile deformation mechanisms of an in-situ Ti-based metallic glass matrix composite at cryogenic temperature.

    Science.gov (United States)

    Bai, J; Li, J S; Qiao, J W; Wang, J; Feng, R; Kou, H C; Liaw, P K

    2016-08-31

    Remarkable tensile ductility was first obtained in an in-situ Ti-based bulk metallic glass (BMG) composite at cryogenic temperature (77 K). The novel cryogenic tensile plasticity is related to the effective accommodation of ductile body-centered cubic dendrites at 77 K, characteristic of the prevailing slip bands and dislocations, as well as lattice disorder, which can effectively hinder the propagation of critical shear bands. The greatly increased yield strength of dendrites contributes to the high yield strength of composite at 77 K. A trend of stronger softening is observed at low temperature, and a criterion is proposed to understand the softening behavior. The current research could also provide a guidance to the promising cryogenic application of these new advanced BMG composites.

  14. Tensile deformation mechanisms of an in-situ Ti-based metallic glass matrix composite at cryogenic temperature

    Science.gov (United States)

    Bai, J.; Li, J. S.; Qiao, J. W.; Wang, J.; Feng, R.; Kou, H. C.; Liaw, P. K.

    2016-08-01

    Remarkable tensile ductility was first obtained in an in-situ Ti-based bulk metallic glass (BMG) composite at cryogenic temperature (77 K). The novel cryogenic tensile plasticity is related to the effective accommodation of ductile body-centered cubic dendrites at 77 K, characteristic of the prevailing slip bands and dislocations, as well as lattice disorder, which can effectively hinder the propagation of critical shear bands. The greatly increased yield strength of dendrites contributes to the high yield strength of composite at 77 K. A trend of stronger softening is observed at low temperature, and a criterion is proposed to understand the softening behavior. The current research could also provide a guidance to the promising cryogenic application of these new advanced BMG composites.

  15. Metals in bulk deposition and surface waters at two upland locations in northern England.

    Science.gov (United States)

    Lawlor, A J; Tipping, E

    2003-01-01

    Concentrations of aluminium and minor metals (Mn, Ni, Cu, Zn, Sr, Cd, Ba, Pb) were measured in precipitation and surface water at two upland locations (Upper Duddon Valley, UDV; Great Dun Fell, GDF) in northern England for 1 year commencing April 1998. At both locations, the loads in bulk precipitation were at the lower ends of ranges reported for other rural and remote sites, for the period 1985-1995. The deposited metals were mostly in the dissolved form, and their concentrations tended to be greatest when rainfall volumes were low. The concentrations of Cu, Zn and Pb in deposition were correlated (r2 > or = 0.40) with concentrations of non-marine sulphate. Three streams, ranging in mean pH from 5.07 to 7.07, and with mean concentrations of dissolved organic carbon (DOC) waters at each location, and temporal variations in individual waters, can be explained qualitatively in terms of sorption to solid-phase soil organic matter and mineral surfaces, complexation and transport by DOC, and chemical weathering. The UDV catchments are sinks for Pb and sources of Al, Mn, Sr, Cd and Ba. The GDF catchments are sources of Al, Mn, Ni, Zn, Sr, Cd and Ba. Other metals measured at the two locations are approximately in balance. Comparison of metal:silicon ratios in the surface waters with values for silicate rocks indicates enrichment of Ni and Cu, and substantial enrichment of Zn, Cd and Pb. These enrichments, together with high metal deposition in the past, make it likely that concentrations of the metals in the surface waters are governed by release from catchment pools of atmospherically-deposited metal. The catchments appear to be responding on a time scale of decades, possibly centuries, to changes in metal deposition. For the more acid waters at UDV, the calculated free-ion concentrations of Al are similar to published LC50 values for acute toxicity towards fish. The free-ion concentrations of Ni, Cu, Zn and Cd in all the surface waters are one-to-four orders of

  16. Coupling of caged molecule dynamics to Johari-Goldstein β-relaxation in metallic glasses

    Science.gov (United States)

    Wang, Z.; Ngai, K. L.; Wang, W. H.; Capaccioli, S.

    2016-01-01

    Three recently published papers have discovered a general property of the fast caged dynamics observed in the glassy states of polyalcohols (S. Capaccioli et al., J. Phys. Chem. B 119, 8800 (2015)), amorphous polymers (K. L. Ngai et al., J. Phys. Chem. B 119, 12502 (2015)), and van der Waals molecular glass-formers (K. L. Ngai et al., J. Phys. Chem. B 119, 12519 (2015)). The fast caged dynamics are manifested as nearly constant loss (NCL) in dielectric and mechanical susceptibility. Shown before in these papers is the intensity of the caged dynamics change temperature dependence at a temperature THF nearly coincident with the secondary glass transition temperature Tgβ, at which the Johari-Goldstein (JG) β-relaxation time τJG reaches ˜103 s. Evidently this finding indicates the coupling of the caged dynamics to the secondary glass transition. The glass-formers considered so far are all soft matters. However, the generality of the phenomenon and its explanation implies that the relation, THF ≈ Tgβ, should be observed in other classes of glass-formers. In this paper, we extend the consideration of the phenomenon and explanation to metallic glasses, which are not soft matter. The experimental data presented show the same phenomenon, supporting its generality and fundamental importance in the physics of glass and glass transition.

  17. Molecular dynamics simulations of the structure evolutions of Cu-Zr metallic glasses under irradiation

    Science.gov (United States)

    Lang, Lin; Tian, Zean; Xiao, Shifang; Deng, Huiqiu; Ao, Bingyun; Chen, Piheng; Hu, Wangyu

    2017-02-01

    Molecular dynamics simulations have been performed to investigate the structural evolution of Cu64.5Zr35.5 metallic glasses under irradiation. The largest standard cluster analysis (LSCA) method was used to quantify the microstructure within the collision cascade regions. It is found that the majority of clusters within the collision cascade regions are full and defective icosahedrons. Not only the smaller structures (common neighbor subcluster) but also primary clusters greatly changed during the collision cascades; while most of these radiation damages self-recover quickly in the following quench states. These findings indicate the Cu-Zr metallic glasses have excellent irradiation-resistance properties.

  18. Characterization of Zr-Cu Base Metallic Glasses by means of Hydrogen Internal Friction Peak

    OpenAIRE

    Mizubayashi, H.; Nakamura, I.; Yamagishi, K.; Tanimoto, H.

    2007-01-01

    The hydrogen internal friction peak in Zr50-metallic glasses (Zr50Cu50, Zr50Cu40Al10 and Zr50Cu35Al10Ni5) was studied. The hydrogen internal friction peak was shifted exponentially to lower temperatures with increasing hydrogen concentration similarly to other Zr-Cu base metallic glasses reported in the literature. The peak height increased in proportion to the square-root of hydrogen concentration. These results were discussed in the view point of the hydrogen induced structural relaxation i...

  19. Formation of quasicrystals in Zr46.8Ti8.2Cu7.5Ni10Be27.5 bulk glass

    DEFF Research Database (Denmark)

    Wanderka, N.; Macht, M. P.; Siedel, M.;

    2000-01-01

    The formation of the quasicrystalline phase is observed as a first step of crystallization during isothermal annealing of the Zr46.7Ti8.3Cu7.5Ni10Be27.5 bulk glass. The structure of the quasicrystals and the sequence of phase formation have been investigated by x-ray powder diffraction and transm......The formation of the quasicrystalline phase is observed as a first step of crystallization during isothermal annealing of the Zr46.7Ti8.3Cu7.5Ni10Be27.5 bulk glass. The structure of the quasicrystals and the sequence of phase formation have been investigated by x-ray powder diffraction...

  20. Spectroscopic Properties and Judd-Ofelt Theory Analysis of Er3+-Doped Heavy Metal Oxyfluoride Silicate Glass

    Institute of Scientific and Technical Information of China (English)

    徐时清; 杨中民; 戴世勋; 张军杰; 胡丽丽; 姜中宏

    2004-01-01

    Er3+-doped heavy metal oxyfluoride silicate glass was fabricated and characterized, and the absorption spectrum and fluorescence spectrum of the glass were studied. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6), spontaneous transition probability, fluorescence branching ratio and radiative lifetime of each energy levels for Er3+ were calculated by Judd-Ofelt theory, and stimulated emission cross-section of 4I13/2→4I15/2 transition was calculated by McCumber theory. The results show that fluorescence full width at half maximum and stimulated emission cross-section of Er3+-doped heavy metal oxyfluoride silicate glass are broad and large, respectively. Compared with other host glasses, the gain bandwidth property of Er3+-doped heavy metal oxyfluoride silicate glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses.