bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Hydrolysis Conditions on the Characteristics of PbTiO3 Gels and Thin Films
Authors: Budd K. D. , Dey S. K. , Payne D. A.
Published: March 2011

Sol-gel processing represents a promising method of fabrication for thin films of electronic ceramics which are useful in a number of packaging and device applications. In this study, the influence of acid and base catalysts on the structure of PbTiO3 gels and films (0.1-1.0μm) was investigated, for the purpose of inducing and identifying gel structures which were the most suitable as precursors for thin dielectric layers. Continuous, crack-free films, with dielectric strengths in excess of 106 V/cm were developed. Basic solutions gelled rapidly, phase separated, and were probably more crosslinked than acidic gels. Acidic gels seemed more capable of polymeric rearrangement during drying, yielding denser amorphous structures with microcrystalline regions. High-field dielectric constants (1 MV/m ac) in the range K=30–40, and K=160–170, were determined for amorphous and crystalline films, respectively.
Chemical Processing of BaTiO3 Based ceramics
Authors: Rehspringer J. L. , Bernier J. C.
Published: March 2011

For multilayers capacitors, submicron BaTiO3 powders are synthetised by chemical routes including gels. Three routes are described, oxalate precipitation, alkoxide gels and carboxyalkoxide polymerisations. Powders characteristics, relations between grain sizes, agglomerates, sintering capabilities and dielectric properties are discussed
Multilayer Ceramic Capacitors Based on Pb(Mg1/3Nb2/3)O3
Authors: Bouquin O. , Lejeune M. , Boilot J. P.
Published: March 2011

Multilayer capacitors were made from Pb(Mg1/3Nb2/3)O3 compositon by an usual technique: ceramic green sheets formed by slip casting method, printed with an 70% wt Ag- 30% wt Pd internal electrode and sintered at temperature ranging from 950 to 11OO°C. Chip capacitors exhibit large capacitance and temperature characteristics meet Z5U specification. Electrical properties of MLC based on PMN depend on specific parameters such as the average concentration of pyrochlore phase and perovskite phase, and the homogeneity degree of dielectric layers. Load humidity life tests show a degradation of some chips which can be connected with the formation of a surface layer rich in pyrochlore phase.
Small Angle Neutron Scattering Studies on Miscibility of Polystyrene and Tetramethyl-Bisphenol A-Polycarbonate Blends
Authors: Yang Hsinjin , O'Reilly J. N.
Published: March 2011

The miscible blend of polystyrene (PSH) and tetramethyl-bisphenol A-polycarbonate (TMPC) has been previously studied by differential scanning calorimetry (DSC), viscoelasticity, and microscopy. In this study, small-angle neutron scattering (SANS) has been applied to obtain the quantitative interaction parameter (X) of this blend at room temperature. Deuterated polystyrene (PSD) was used for the scattering contrast in the study. The PSD/TMPC blends show a single Tgover the whole range of composition from the DSC measurements, whicg is the same as the Tgof PSH/TMPC blend.

The interaction parameter was calculated from the de Gennes scattering intensity function of miscible polymer blends, which is based on the random phase approximation. As expected for a miscible system, all X values are negative over the range of composition. It is also found that the X is composition-dependent. Furthermore, the correlation length of the concentration fluctuation is approximately twice the segment length 21–32 Å of the component polymer (PSD = 6.7 Å and TMPC = 18.3 Å), implying that the mixing of this blend is effectively at segmental level.
Scattering by Mixtures of Statistical copolymers. Application to the Problem of Phase Separation in the Liquid State
Authors: Benoit Henri C.
Published: March 2011

It is well known [1] that the majority of the classical polymers are incompatible. This means that it is impossible to mix them without having phase separation. This is sometimes advantageous for industrial applications but, from a fundamental point of view, it makes it difficult to measure the interaction parameter X between these polymers (for this purpose one has to have the two polymers in a single phase).
Small-Angle X-Ray Scattering Study of Microand Macro-Phase Separations in Blends of Block Copolymer with Homopolymer
Authors: Roe R. J. , Nojima S.
Published: March 2011

The order-disorder phase transition behavior exhibited by blends of a styrene-butadiene diblock copolymer (76% styrene) with a polystyrene of various molecular weight (from 2,200 to 50,000) is studied by means of small-angle X-ray scattering. With a polystyrene of a relatively short chain length the blend, on lowering the temperature, undergoes a microphase separation, and the scattering curve shows a peak at a finite scattering angle. With a polystyrene of relatively long chain length, the scattered intensity curve shows additional low angle component with intensity increasing rapidly as q→0, and this is interpreted in terms of the macrophase separation accompanying the transition from the disordered to ordered phase.
Exafs Analysis of Ionomers
Authors: Ding Y. S. , Pan H. K. , Régister R. A. , Cooper S. L.
Published: March 2011

Extended x-ray absorption fine structure (EXAFS) spectroscopy has beensuccessfully applied to the analysis of the ionic domain microstructure inzinc and rubidium neutralized ionomers. In dehydrated zinc neutralizedionomers, the zinc cation was found to be tetrahedrally coordinated to oxygenatoms. For ionomers with hydrocarbon backbones, these oxygen atoms mayoriginate from the sulfonate or carboxylate groups. For ionomers withperfluorinated backbones, some of the oxygen atoms may be ascribed to watercoordination as well. In fully hydrated zinc neutralized ionomers, thezinc cation exists as Zn( H2O)62+. In contrast, the fully hydrated monovalentrubidium neutralized ionomers exhibited a highly disordered environmentabout the cation.
X-Ray Analysis of the Structure of HM-50 Copolyamide Fibers
Authors: Cageao Ronald A. , Biswas Amit , Blackwell John
Published: March 2011

X-ray analysis methods have been used to investigate the structure of the high strength HM-50 copolyamide fiber produced by Teijin, Ltd. of Japan [1,2]. The fiber is prepared of a 50/25/25 mole ratio of the monomers shown below.
Raman Scattering and Photoluminescence of Pristine and Ion Implanted Langmuir-Blodgett Polydiacetylene Thin Films
Authors: Kaneko F. , Dresselhaus M. S. , Braunstein G. , Kouno T. , Liu Y. , Shibata M. , SAito K. , Kobayashi S.
Published: March 2011

Fundamental optical properties of Langmuir-Blodgett polydiacetylene (LB PDA) ultra thin films are investigated. The LB films exhibit a strong absorption peak at about 16000 cm-1 and a weak and broad peak at about 17500 cm-1; the color of the film is blue. After annealing at 90°C, a blue shift of the absorption peaks is observed; that is, the color of the LB films changes from blue to red. The phase transition corresponding to the color change is studied using Raman spectroscopy as a function of annealing temperature. For annealing temperatures between 50 and 60°C, the results show significant change in the ratio of Raman line intensities due to C≡C and C=C stretch modes. Such a transition is also observed for laser annealed LB PDA films. Furthermore, the photoluminescence (PL) properties of pristine (blue), annealed (red) and ion implanted (red) LB PDA films are investigated. The photoluminescence of both pristine and annealed LB PDA films show sharp peaks at about 15500 cm-1. The annealed LB PDA films have an additional small peak or shoulder at about 18000 cm-1. The photoluminescence peaks of red films implanted with 200keV As+ ions are observed at about 16000 cm-1 and become broad with increasing ion implantation dose in the range 1012–1015 cm-2.
Studies of Molecular Orientation in Deformed Semicrystalline Polymers by X- Ray Scattering Employing Synchrotron Radiation
Authors: Röber S. , Gehrke R. , Zachmann H. G.
Published: March 2011

Introduction

The possibility of using synchrotron radiation as a source of X-rays for scattering experiments has considerably improved the methods of the characterisation of the molecular orientation and molecular order in polymers. In another publication [1], it has been shown that the morphology of ultra highly drawn polyethylene is correlated to the kinetics of isothermal melting, as determined by X- ray scattering employing synchrotron radiation. In this paper we present some results on chain orientation and orientation of crystal lamellae surfaces in uniaxially and biaxially drawn films of polyethyleneterephthalate (PET). These results were obtained by inserting a pole figure goniometer into the synchrotron radiation beam and measuring the wide angle X-ray scattering (WAXS) and small angle X- ray scattering (SAXS) with different angles of incidence of the primary beam onto the sample.
Polymer Chain Deformation in Stretched and Swollen Elastomers
Authors: Ullman Robert
Published: March 2011

In the early theories of rubber elasticity, the retractive force and change in free energy of a stretched specimen were calculated from the deformation of the polymer chains of which the rubber network was formed. The mean chain deformation was presumed to be the same as that of the macroscopic specimen, an assumption which seemed reasonable, but could not be confirmed experimentally. Small angle neutron scattering (SANS) made measurement of chain dimensions possible, and it was soon discovered [1], [2] that the actual relation between dimensional changes of the polymer chain and deformation of the specimen was not at all what had been assumed.

SANS studies of carefully prepared elastomeric networks provide the most direct experimental information required for a molecular theory of rubber elasticity, and have stimulated many new developments.
A Deformation-Induced Phase Separation in the Solid State
Authors: Lefebvre J. M. , Porter R. S. , Wignall G. D.
Published: March 2011

Amorphous Polymethylmethacrylate/Polyethyleneoxide blends deformed by solid-state coextrusion exhibit anomalous anisotropic Small Angle Neutron scattering patterns in the low q range. It is shown that upon drawing the samples have undergone phase separation to some extent. The resulting structure of the system is characterized by combining scattering techniques with Differential Scanning Calorimetry.
A Double-Tilt Small Angle Neutron Scattering Experiment on Deformed Poly Mer Systems
Authors: Saraf R. F. , Lefebvre J. M. , Porter R. S. , Wignall G. D.
Published: March 2011

A double rotation goniometer has been mounted in the neutron beam in order to characterize the molecular deformation in polymers subjected to various strain conditions.

The results provide a direct verification of the fiber symmetry in solid state coextruded polymethylmethacrylate (PMMA) and polypropylene (PP) homopolymers.

In the case of the shear banding phenomenon, we have been able to test the validity of the simple shear assumption: it also provides a direct estimate of the finite shear strain involved in the process. As a last illustration ofthe method, we also consider the biaxial deformation of PP and PMMA squeezed under various temperature and strain-rate conditions.
Time-Resolved Saxs and Waxs Studies on Ordering Process in Oriented Crystallization of Polymers
Authors: Saijo Kenji , Hashimoto Takeji
Published: March 2011

Mechanism and dynamics of the ordering process in oriented crystallization of polymers were investigated by time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXS). As a model system for the oriented crystallization, a cross-linked polybutadiene rubber with a high cis-1,4-linkage was chosen, and the structure evolution during the isothermal crystallization was investigated under constant elongations by real time and in situ analyses of the microscopic observables such as long spacing, crystallite size, SAXS integrated intensity, WAXS crystallinity and WAXS line width as well as a macroscopic observable such as stress. The isothermal ordering processes were explored in three different crystallization regimes: crystallization from (i) unoriented melts, (ii) weakly-to-moderately oriented melts and (iii) highly oriented melts.
The Physics of Photons and Neutrons with Applications of Deuterium Labeling Methods to Polymers
Authors: Wignall G. D.
Published: March 2011

Over the past decade small-angle neutron scattering (SANS), has found numerous applications in the fields of biology, polymer science, physical chemistry, materials science, metallurgy, colloids., and solid state physics. A number of excellent references are available [1–4] which contain basic neutron scattering theory though these text books reflect the origins of the technique and the examples are largely drawn from physics e.g., single crystals, simple liquids, monatomic gases, liquid metals, magnetic materials, etc. In view of the large numbers of nonspecialists who are increasingly using neutron scattering, the need has become apparent for presentations which can provide rapid access to the method without unnecessary detail and mathematical rigor. In the field of polymer science several reviews have been written to meet this need [5–8] including a recent comprehensive survey of neutron scattering studies of polymers [9] to Which reference will be made for detailed derivations of the expressions used below. This article, along with others in this volume, is meant to serve as a general introduction to the symposium “Scattering Deformation and Fracture in Polymers,” and is intended to aid potential users who have a general scientific background, but no specialist knowledge of scattering, to apply the technique to provide new information in areas of their own particular interests. In view of space limitations, the general theory will be given in the case for neutron scattering and analogies and differences with photon scattering (x-rays) will be pointed out at the appropriate point.
Small Angle X-Ray Scattering Studies of Fatigue in Polystyrene
Authors: Brown H. R. , Kramer E. J. , Bubeck R. A.
Published: March 2011

Small angle scattering has been used to study the mechanical fatigue of crazes in polystyrene. The high radiation intensity obtainable from a synchrotron has permitted the examination of the processes that occur during the fatigue in real time. Both the short term changes that occur within a single cycle and the long term changes that occur over many cycles have been observed.

Most of the craze growth, as measured by the scattering invariant obtained at peak deformation, occurred in the first cycle of fatigue. However the craze fibril diameter, obtained by Porod analysis, doubled over 250 cycles. As the volume of craze was not growing during during the fatigue this fibril diameter increase was believed to occur by change, that is coalescence, of the preexisting fibrils.

The SAXS patterns obtained at a number of different deformations within a single cycle were compared with calculated patterns obtained assuming that the fibrils bend in a sinusoidal manner. Good qualitative agreement was obtained so it was concluded that the craze fibrils showed considerable deformation as the craze was unloaded and then straightened out again on reloading. When the ratio of minimum to maximum deformation was decreased from 0.9 to 0.5 the fibril deformation (contraction) increased to 10% with the fibrils remaining straight. As the minimum deformation was decreased below this the craze stress tends to zero and fibril buckling was evident. The main changes in fatigue lifetime occurred over the regions where there fibrils were straight, perhaps because buckling involves relatively small deformations.
Optical Interferometry on Crazes in Solvent Vapours at Very Low Pressure in Polymethylmethacrylate.
Authors: Schirrer R. , Galleron G.
Published: March 2011

The fracture toughness and the craze shape of a propagating single crack/craze in polymethylmethacrylate has been measured in a very low pressure toluene gas environment by means of optical interferometry. Below a velocity of 0.01 mm/s the craze size increases up to 4 times the craze size in air, whereas the fracture toughness remains identical to the toughness in air. Above 0.01 mm/s the crack/craze behaves like a crack/craze in air.
Small Angle Neutron Scattering and Time Resolved Small Angle X-Ray Scattering Studies of Triblock Copolymers in Extension
Authors: Richards R. W. , Mullin J. T.
Published: March 2011

Linear triblock copolymers of styrene and isoprene with isoprene as the centre block are microphase separated elastomers in the solid state. The styrene blocks form domains of regular morphology 1arranged on a paracrystalline lattice with considerable long range order. Domain symmetry is chiefly determined by the composition of the block copolymer; only cylindrical domain geometry is dealt with here. Three levels of organisation can be recognised.
The Coupling Model: A Fundamental Mechanism Governing Time Dependent Properties of Relaxations, Structural Recovery and Nonlinear Viscoelasticity
Authors: Rendell R. W. , Ngai K. L. , Yee A. F.
Published: March 2011

The recent renewal of interest in the time dependent response of complex material systems stems both from their increasing importance and from recent advances in theoretical tools and concepts. This paper describes one of these advances, the coupling model of relaxation. The coupling model proposes a view of how relaxation proceeds in time in which a primitive relaxation mode is coupled to its complex surroundings. Examples of the coupling model predictions for terminal relaxations, primary-segmental relaxations including physical aging, and secondary relaxations in polymers are described. It is able to confront and quantitatively explain several long-standing problems and anomalies for which traditional approaches, in their present form, such as distributions of relaxation times, free volume, configuration entropy and reptation are not successful. The coupling model response function is also appropriate for structural nonequilibrium and its predictions for volume recovery are described. The same coupling model response function is used as a timedependent kernal in a constitutive equation to discuss nonlinear viscoelasticity. The model incorporates the strain history dependence and allows for the evolution of material structure. Using information from strain-tickle experiments on polycarbonate and polyetherimide, we show that the coupling model reproduces the essential features observed experimentally for a variety of strain histories.
Nonlinear Viscoelastic Deformation in Polymeric Glasses
Authors: Matsuoka Shiro
Published: March 2011

The dielectric, mechanical and volumetric relaxation data, and stress-strain data in tension, shear and uniaxial compression for polymeric glasses are compared. The relaxation phenomenon is viewed as a thermodynamically irreversible response to a perturbation in the configurational state. The relaxation behavior is apparently linear only in the limit of a very small perturbation, but otherwise generally nonlinear. Adam-Gibbs' entropy equation [1] has previously been shown to describe the dielectric and volumetric relaxation data better than Doolittle's free volume equation [2]. The temperature and the structure, i.e., history, dependence of mechanical relaxation time is shown to agree with the A-G theory better Than the Doolittle theory, in that the former predicts an Arrhenius type dependence on the temperature when the structural parameter, in this case the entropy, is fixed, while the latter predicts the temperature independence if the fractional free volume is fixed in the glassy state. The temperature dependence of the distribution of relaxation times is shown to agree qualitatively with the dynamic Ising model of Fredrickson and Andersen [3] (F-A model) involving the cooperativity of molecular motions in dense liquids.
Microstructure and Fracture of Engineering Polymers and Composites
Authors: Friedrich K.
Published: March 2011

The fracture properties of engineering polymers and composites are strongly affected by two major areas of influence. The first one covers the microstructural parameters of the material, whereas the second one includes the external testing conditions. In this contribution, it is mainly outlined how area one can determine the fracture characteristics. An introductory section illustrates the variety of microstructural details, for example molecular structure and semicrystalline polymer morphology, and filler related factors, such as volume fraction of reinforcing fibers, their orientation etc. In the following part, effects of these parameters on fracture mechanical properties are discussed. It is distinguished between the fracture behavior of unfilled engineering polymers, of short fiber reinforced, injection molded thermoplastics, and of continuous fiber composite laminates. In the latter group, special emphasis is given to the effect of new, high temperature resistant thermoplastic matrices, for instance PEEK, on the interlaminar fracture energy of the composites.
Fracture of Polymers Under Repetitive Loading
Authors: Sauer J. A. , Chen C. C.
Published: March 2011

The fracture surface morphology of various polymer specimens, fractured under alternating loading, has been examined by scanning electron microscopy. Illustrations are given of both typical and unusual fracture surfaces and the influence of such variables as composition, molecular weight, presence of a dispersed second phase and induced thermal effects is discussed.
Ultinite Mechanical Properties of Polymer Fibers a Theoretical Approach
Authors: Termonia Yves , Smith Paul
Published: March 2011

A stochastic Monte-Carlo approach, based on the kinetic theory of fracture, has been used to study the axial maximum tensile strength of polymer fibers. The approach is entirely microscopic and the inhomogenous distribution of the external stress among atomic bonds near the chain ends is explicitly taken into account. Both primary and secondary bonds are assumed to break during fracture of the polymer fiber. The approach has been applied to perfectly oriented and ordered polyethylene and poly(p-phenylene-terephthalamide) fibers. The influence of the molecular weight, temperature ard strain rate on the axial tensile properties are presented.
Spectroscopic Characterization of the α⇌β Crystalline Phase Transition in Poly(Butylene Terephthalate) and its Copolymers with Poly(Tetramethylene Oxide).
Authors: Dobrovolny-Marand Eva , Hsu Shaw Ling
Published: March 2011

The stress-induced crystalline α⇌β phase transition found in poly(butylene terephthalate) and its copolymers with poly(tetramethylene oxide) has been studied by Fourier transform infrared spectroscopy coupled with mechanical measurements. The phase transformation behavior was explained in terms of a cooperative model which considered both intermolecular as well as intramolecular interactions within the crystal. It was shown that the strength of the intramolecular interactions increased with length of the hard segments and that the strength of the intermolecular interactions increased with perfection and lateral size of the crystals. The intermolecular interaction was assumed to be dominated by the interaction between neighboring terephthalate groups. The “mean” intramolecular energy was estimated at 0.40 Kcal/mole. This calculation was based on the potential energy of rotations of a carbonyl group about a benzene-carbonyl bond. Cooperativity between chains diminished when the surface to volume ratio increased above 2 x 10-2 Å-1.
Small-Angle Scattering from Disordered Systems
Authors: Schaefer Dale W.
Published: March 2011

A general discussion of scattering from disordered materials is presented. The parameters which characterize structure are illustrated in real-space and are also identified in the reciprocal-space profile measured in a scattering experiment. Scattering from fractal objects is described in detail. To illustrate the interpretation of scattering data, the growth and structure of fumed silica is discussed. The flame growth of silica is explained in terms of monomer-cluster ballistic polymerization in the early stages and diffusion-limited aerosol aggregation in the latter stages.
Molecular Mechanism of Deformation in Epoxies – A Neutron Scattering Study
Authors: Wu Wen-Li
Published: March 2011

Neutron scattering was used to investigate the molecular mechanism of large strain deformation in epoxies. Partially deuterated diglycidyl ether of bisphenol A (DGEBA) was cured with either tri- or di-amines of different molecular weights. The change of the average distance between crosslinks along the epoxy and the amine linkages could easily be determined from the shift in the positions of the scattering maxima. It was found that the average distance between crosslinks remained almost unchanged along both the amine and the epoxy linkages as the bulk material underwent a large deformation. The above results are discussed in terms of the functionality of the junctions as well as the molecular weight between crosslinks. Comparisons are also made between the solid state deformation results and those from swollen networks which did show a substantial increase inaverage distance between crosslinks.
An Automated Laboratory Apparatus for the Production of Rapidly Solidified Submicron Powders
Authors: Perel Julius , Mahoney John F. , Taylor Scott , Shanfield Zef , Levi Carlos
Published: March 2011

The Electrohydrodynamic (EHD) method of spraying fine liquid droplets from a liquid state, in a vacuum environment, was developed and used to produce amorphous, microcrystalline, single crystal, bicrystalline and tricrystalline powders. Studies of these powders have contributed towards increasing the knowledge of extended solubility, nucleation, metastable phases, undercooling effects, etc. Coatings and films have been produced by collecting the liquid droplets before solidification. An automated instrument based upon the EHD method, the Micro-Particle Processor, is computer operated and allows a material scientist not completely acquainted with the EHD process to perform sophisticated experiments on materials of his choosing. Electron transparent powders close to 3μm and large powders up to l00μm have been collected and observed. Cooling rates above 107K/s have been achieved. Applications using powders include: new alloy compositions, use as AEM standards, in-situ remelt experiments in the electron microscope, etc.
Consolidation of Ni60Nb40 Metallic Glass Strips into Metal Matrix Composites
Authors: Cytron S. J.
Published: March 2011

To fully utilize the promising mechanical properties of metallic glasses, consolidation techniques need to be developed to incorporate them into large bulk forms. This paper describes preliminary results on the consolidation of Ni60Nb40 metallic glass strips into an aluminum alloy matrix. The consolidation was achieved without the degradation of the metallic glass by employing a superplastic aluminum alloy as the matrix material. The consolidations were accomplished at a superplastic forming temperature compatible with the metal matrix material and sufficiently below the critical 650°C crystallization temperature of the Ni60Nb40 metallic glass. Initial studies employed an atuminum − 5% calcium − 5% zinc alloy as the metal matrix material.
Growth Kinetic Limitations During Rapid Solidification
Authors: Boettinger William J.
Published: March 2011

The importance of growth kinetics in the development of the microstructure of rapidly solidified alloys is described. Growth kinetics are conveniently divided into diffusion kinetics and interface attachment kinetics. The former, which are used extensively for the analysis of slow rate solidification, can be extended to high solidification rates to predict some microstructural features; e.g., the limitations on eutectic growth rate which can promote the formation of metallic glass, and the reduction of microsegregation. At the highest rates interface attachment kinetics must be included. Some microstructural effects of the velocity dependence of the partition coefficient will be described.
Techniques for Investigating Structure and Composition with High Spatial Resolution
Authors: Vander Sande John B.
Published: March 2011

The techniques of scanning transmission electron microscopy and field iron microscopy/atom probe are briefly described. The advantages of these techniques for high spatial resolution compositional analysis are discussed and examples cited.
Influence of Solidification Parameters on the Microstructure of Rapidly Quenched Fe-Ni-B Alloys
Authors: KÖster Uwe , Herold Ursula , Krause Dieter
Published: March 2011

The microstructure of Fe-Ni-B alloys rapidly quenched by melt spinning has been investigated by means of light and electron microscopy. Depending on the surface velocity of the quenching wheel and the boron concentration a large variety of microstructures has been observed: increased solubility of boron, microstructures with different metastable crystalline compounds or metallic glasses.

Plotting the as-cast microstructures versus the quenching rate has been found to be very useful for arranging the large amount of results and/or for predicting particular microstructures. Due to an extremely large gradient in the microstructure across the ribbon thickness this method of forming particular microstructures seems to be only of limited advantage. Controlled crystallization reactions of metallic glasses result in different, but more homogeneous microstructures.
New Magnetic Metallic Glasses with Reduced Metalloid Content
Authors: O'handley R. C. , Grant N. J.
Published: March 2011

Several new magnetic amorphous alloys containing early transition metals (TE) and having reduced metalloid (M) content have been melt spun. Some properties of three examples of this new class, 1) Co80Nb14B6, 2) Co84Nb10B6, and 3) Fe81Nb5B14, are presented. The dominant late transition meta1 (TL) content assures an appreciable magnetic moment while the presence of an early transition metal significantly enhances the stability against crystallization. Crystallization temperatures are 1) 742K, 2) 698K, and 3) 762K for the three alloys, respectively. X-ray diffraction patterns show the materials to be amorphous and to exhibit a large-r correlation length (approximately 2.0 A) that is shorter than is typiclly observed in TL80M20 glasses containing more than one transition meta) species (approximately 2.3 − 2.5A). The coercivities of the glassy compositions range from 30 to 70 m0e.
Calculation of the Crystallization Behaviour of Metallic Glasses
Authors: Bergmann H.W. , Fritsch H.U.
Published: March 2011

A method is proposed to calculate the crystallization behaviour of multicomponent metallic glasses with several phases. Various geometric shapes of precipitate can be considered. The model also takes into account changes in concentration which arise during precipitation.
Thermal Expansion of Amorphous Iron-Chromium-Boron Alloys
Authors: Hunger G. , Bergmann H. W. , Mordike B. L.
Published: March 2011

In amorphous iron-chromium alloys magnetic contraction is superimposed on the thermal expansion. Depending on the proportion of antiferromagnetic chromium the resultant coefficient of expansion is either positiv, negative or zero. The chromium content also changes the Curie temperature. Relaxation processes have a marked effect on the thermal expansion. Long term and short term expansion behaviour was compared and discussed. In addition the crystallization behaviour and mechanical properties of the alloys are reported.
Sorption of Hydrogen and Deuterium in a Glassy Pd-Si Alloy by a Bendingcantilever Method
Authors: Berry B.S. , Pritchet W.C.
Published: March 2011

The dilatation caused by the sorption of H and D in amorphous samples of melt-spun Pd82Si18 and sputter-deposited Pd81Si19 has been measured at room temperature for ambient charging pressures P up to 760 torr. By comparison with the strength of the Gorsky relaxation, it is concluded that (a) the dilatations per hydrogen and deuterium atom are identical and independent of concentration and (b) the non-linearity of the dilatation vs. p1/2 isotherms is due solely to a deviation from Sieverts' law. The isotherms exhibit a distinct isotope-dependence, of a similar nature to that for crystalline Pd. A sputterdeposited film is found to dissolve more H or D than a melt-spun ribbon, due possibly to a less structurally-relaxed configuration.
Fretting of Amorphous Alloys
Authors: Becker Reinhard , Sepold Gerd
Published: March 2011

Amorphous surface layers produced by bonding metglas ribbons onto steel specimens were tested for their resistance to fretting. Friction and weight loss were determined and the worn surfaces were examined optically. There was no general tendency towards a better wear resistance of the tested amorphous metals as compared to crystallized metals or to a simple structural steel. The results will be discussed.
The Thermodynamics of the Glass Transition
Authors: Hillert Mats
Published: March 2011

The kinetic theory of the glass transition is examined. Some modifications are suggested in order to overcome some shortcomings. As a result, a thermodynamic description of the glass transition is obtained. It is demonstrated that the glass transition represents the beginning of a very gradual process of melting in the amorphous state.
Environmental Cracking of Amorphous Alloys
Authors: Ashok S. , Slavin T. P. , Stoloff N. S. , Glicksman M. E.
Published: March 2011

Six amorphous metals have been tested in liquid metal environments or while charging with hydrogen. Differences in sensitivity to each environment are correlated with fractographic features. Evidence in support of enhanced shear as the mechanism of environmental cracking is presented.
Perpendicularly Crystallized Ribbons by Means of Rapid Solidifications from Melts
Authors: Tsuya Noboru , Ichi Arai Ken , Ohmori Kenji
Published: March 2011

Silicon-iron alloy ribbons containing around 6 wt% silicon and Sendust alloy ribbons in the crystalline state were prepared by a rapidly quenching roll method. In the as-prepared ribbons columnar grains about 1Oμm in diameter wer observed to grow from the surface to the middle part of the ribbon thickness. For the high silicon-iron ribbons annealed at 1200°C for 30 minutes the grain size was more than 1 mm and the texture was highly oriented to (100)[0kl] cube-on-face. The coercive force was 55 mOe for the 6.6Si 93.4Fe ribbons annealed at 1180°C for 60 minutes in vacuum, and the average magnetic iron loss W15/50 and W10/50 of the ribbons having the coercive force of 80 mOe was 0.7 Watt/kg and 0. 25 Watt/kg, respectively. For Sendust ribbons, the lowest coercive force was 8mOe when the ribbons was annealed at 1040°C for 30 minutes and then cooled at the rate of 60 deg/hour down to 550°C in vacuum. The recording heads made of laminated Sendust ribbons exhibit much better recording characteristics than ferrite heads, while frequency response remains flat.
Analysis of a Rapidly Solidified High-Phosphorus Austenitic Steel Containing an Amorphous Phase
Authors: Kelly T. F. , Olson G. B. , Vander Sande J. B.
Published: March 2011

Rapid solidification of a high-phosphorus austenitic steel produces a fine cellular solidification structure containing an amorphous phase at the cell walls. The amorphous phase, which is stable to ∼500°C, is enriched in phosphorus and chromium, but contains significantly less phosphorus than conventional glass-forming alloys. Hot consolidation of powders produces a chemically-uniform metastable austenite which can be effectively precipitation hardened by phospho-carbides.
Grain-Coarsening Resistance and The Stability of Second-Phase Dispersions in Rapidly Solidified Steels
Authors: Olson G. B. , Ling H. C. , Montgomery J. S. , Vander Sande J. B. , Cohen M.
Published: March 2011

Control of alloy composition and processing to achieve grain coarsening resistance in rapidly solidified alloys is examined via the theory of grain boundary pinning and particle coarsening. The principles are illustrated for the case of manganese sulfides in steels. A thermodynamic survey of potential stable dispersed phases identifies TiN and rare-earth sulfides as particularly promising for alloy development via rapid solidification.
Microstructure of a Rapidly Solidified Al-Fe-Co-Ni Alloy
Authors: Sanders T. H. , Paris H. G. , Mullins J. W.
Published: March 2011

Observations made on different consolidated and wrought microstructures suggested that in addition to the simple variations in size and size distributions there were also differences in shape. Furthermore, clusters of oriented precipitates were often observed. The different particle morphologies were related to solidification rate effects. This paper describes the changes in microstructure which occur during the heating of rapidly solidified AI-3.3Fe-4.6Co-2.3Ni splat.
The β → α Transition in Rapidly Quenched Sn-Ge Alloys
Authors: Gallerneault W.M. , Smith R.W.
Published: March 2011

Dilute Sn-Ge alloys were prepared as ribbons by meltspinning using a 4" copper drum. They were then transformed into grey tin at 242 K in the as-cast-condition, and after annealing. It is shown that germanium: (1) when in solid solution impedes β → α transformation; (2) when in solid solution cannot effect nucleation; and (3) has a solubility in α-Sn in excess of 1 wt. % Ge.

In addition it is proposed that β → α transformation is restricted because the presence of germanium strengthens the β-Sn matrix.
RaneyR Type Nickel Catalysts From Rsr Atomization Of Al-Ni Powders
Authors: Brooks C. S. , Lemkey F. D. , Golden G. S.
Published: March 2011

The synthesis and catalytic properties of hydrogenation catalysts of the RaneyR type derived from aluminum-nickel and aluminum-molybdenum-nickel RSR alloy powders have been evaluated. Two binary aluminum-nickel alloys, RSR 588, with 50 w/o Ni corresponding to currently available RaneyR commercial alloys, and RSR 587, with 28.5 w/o Ni corresponding to the proeutectic composition which produces exclusively Al3Ni as the precursor phase, were synthesized. One ternary, RSR 589, aluminum-molybdenum-nickel alloy with a nickel and molybdenum content to correspond to a commercial promoted RaneyR alloy was prepared.

The hydrogenation catalytic activity for six organic compounds representing diverse functionalities was measured in a bench scale batch liquid slurry catalytic reaction. Each catalyst was suspended in an agitated solution of the reaction (0.8 to 5M) at 22°C under a constant hydrogen over pressure of 0.86 atmospheres. A declining pressure technique was also used as a measure of catalytic activity where the catalyst was suspended in an agitated solution of the three reactants at 80°C at an initial hydrogen pressure of four atmospheres. The reactants selected consisted of acetone, nitrobenzene, itaconic acid, butyronitrile, toluene, and dextrose. The organic functionalities hydrogenated consisted of the conversion of:

(1) Carbonyl to alcohol

(2) Nitro group to amine group

(3) Double carbon bond to a single carbon bond

(4) Nitrile group to an amine group

(5) Aromatic to a hydroaromatic ring

(6) Aldehyde to an alcohol.

RSR 587 catalyst, containing 28.5 w/o nickel, provides superior hydrogenation rates over bulk cast RaneyR nickel catalysts by factors ranging from 2 to 20 for selected reactions. Rapid solidification followed by heat treatmen0t at 850°C of Al ∼42 w/o Ni powders yielded the greatest specific catalytic activity and provides a unique enrichment path for the formation of the peritectic phase, A13Ni, and subsequently the most active skeletal nickel pore structure with the least amount of waste aluminum.
Hot Consolidation/Devitrification of Metallic Glasses — Novel Multiphase Crystalline Alloys in Bulk Shapes With Technological Potentials
Authors: Ray Ranjan
Published: March 2011

Iron, nickel and/or cobalt base metallic glasses with low contents of metalloids, predominantly boron, upon heat treatment at temperatures well above crystallization temperature of the glassy phase transform into ultra-finegrained (microcrystalline) alloys containing finely dispersed boride phases.

Microcrystalline alloys devitrified from glassy phase are characterised by high strength, excellent thermal stability and superior corrosion/oxidation resistance. Mechanical properties of bulk microcrystalline alloys hot consolidated-devitrified from selected low metalloid metallic glass alloys are reported.
Micromechanisms of Crystallization in (Fe,Co,Ni)-Zr Metallic Glasses
Authors: Franke Hans-Georg , KÖster Uwe , Schroeder Hans-Werner , MÜller Johann
Published: March 2011

Depending on the Zr-concentration crystallization of (Fe-,Co,Ni)-Zr glasses has been found by TEM studies to occur by primary and polymorphic crystallization, however, not by eutectic crystallization reactions. Nucleation and growth rates of these ractions have been analyzed systematically. Thermal stability as indicated by orowth as well as nucleation rates decreases with increasing Zr-content and atomic number of the late transition metal. Using this knowledge on nucleation and orowth rates conditions for designing particular microstructures by crystallization reactions can be predicted.
Undercooling Behavior of Liquid Metals
Authors: Perepezko J. H. , Paik J. S.
Published: March 2011

The undercooling of liquid metals is observed often, but is restricted by the catalysis of the most potent heterogeneous nucleation site in contact with the liquid. An experimental approach that yields large undercoolings involves the slow cooling from the melt of a dispersion of stabilized fine (5–20μ) liquid droplets. Droplet studies have extended measurements of the undercooling limit for low melting point metals to the range of 0.3 to 0.4 Tm. In droplets, surface coating and size characteristics usually limit the undercooling and control the uniformity of crystallization behavior. A nonuniform undercooling behavior can produce microstructural variations in powder samples with respect to metastable phases and solute segregation, but these variations can be diminished for isenthalpic solidification of hypercooled liquids. In alloys the trend in nucleation temperature can follow a similar pattern as the composition dependence of the liquidus. With highly undercooled droplets and even at modest ΔT (ΔT ≤ 0.lTm) with known heterogeneous sites, structural modifications such as extended solid solutions and metastable intermediate phases can be generated which are similar to those produced by rapid quenching techniques. These features highlight the importance of a high liquid undercooling as well as a high cooling rate in promoting effective rapid solidification processing treatments.
Phase Transformation Studies of Laser-Processed Fe-0.2%C-Cr Surface Alloys
Authors: Molian A. , Wang P. J. , Khan K. H. , Wood W. E.
Published: March 2011

Phase transformations in laser-processed Fe-0.2%C-Cr surface alloys with 5%, 10%, 20%, and 30%Cr were studied by light and electron microscopy.Alloys containing 5% and 10%Cr were found to be fully martensitic with a dislocated lath type substructure. Thin films of retained austenite and a homogeneous dispersion of fine carbides were observed at the lath boundaries and prior austenite grain boundaries. The alloy with a 20%Cr content showed a unique microstructure of twinnedaustenite needles in a dislocated ferrite matrix while the alloy containing 30%Cr exhibited a dislocated ferrite structure with M23C6 carbides.
Microstructure and Mechanical Properties Of Laser-Processed Ni-Al-Mo Base Alloys
Authors: Snow David B.
Published: March 2011

The addition of molybdenum to nickel base superalloys which contain a γ′ volume fraction of ≦ 0.35 allows them to be consolidated from powder by laser processing at solidification rates of ∼1040C/s. The as-solidified microstructure of these alloys is dendritic, and consists of a fine dispersion ∼20nm cuboidal γ′ in a supersaturated FCC γ matrix. When annealed at 500–700°C, additional age hardening occurs via the precipitation of ≤l0nm, Dla-structure Ni4Mo, DO22- structure Ni3Mo and/or Pt2Mo-structure Ni2Mo. This combined strengthening by very fine γ′ and NixMo dispersions in laser-processed material makes alloys of this type attractive for potential turbine disk applications. However, the 6–15 at % molybdenum required to prevent cracking during laser consolidation renders many of these alloys prone to a previously unreported, embrittling cellular phase transformation, γ + γ′ + NixMo→ γ′ + orthorhombic Ni3Mo, at temperatures of ≦900°C.
Characterization and Properties of Laser Quenched Aluminum Bronzes
Authors: Draper C. W. , Vandenberg J. M. , Preece C. M. , Clayton C. R.
Published: March 2011

Commercial aluminum bronze (Cu-Al-Fe) alloys have been laser quenched with both continuous and pulsed CO2 laser sources. Metastable near surface regions of approximately 10 μm thickness have been produced. The quenched surfaces have been characterized by optical microscopy, SEM, EDX, AES and glancing angle XRD. The behavior of both laser quenched and “as received” conventional surfaces have been tested in both cavitation erosion and corrosion environments. In some cases significant differences are observed and can be rationalized from the microstructural changes accompanying the self quenching.
Property Enhancement in Rapidly Quenched Alloy Surfaces
Authors: Tuli M. , Strutt P. R.
Published: March 2011

Electron beam glazed surfaces on a circular bar are of sufficiently good quality either for direct use or after light mechanical grinding. The technique may be applied for reconstituting plasma deposited layers thereby eliminating porosity and obtaining a highly homogeneous refined microstructure. By this treatment it was found that the microhardness of a plasma deposited layer of chromium carbide in molybdenum binder increased from 525 V.H.N. to 750 V.H.N.
Rapidly Solidified Microstructure in Surface Layers of Laseralloyed Mo on Fe-C Substrates
Authors: Tucker T. R. , Clauer A. H. , Ream S. L. , Walters C. T.
Published: March 2011

Shaped continuous-wave laser beams have been used to alloy molybdenum coatings into Fe-C substrates. The Mo overlay was first deposited by the plasma spray process in an inert gas environment. Slowly scanned laser radiation then melted a layer 2 to 5 times the thickness of the original Coating causing the two metallic species to mix. Melt proceeded from the coating/substrate interface, the Mo melt temperatures being significantly higher than that of the base material. Fusion zone microstructures for individual melt passes appeared to be homogeneous, and molybdenum composition was found to be relatively uniform. With overlapping melt passes, the microstructures became more complex with heat effects apparent in the overlap regions.
Morphological Stability of Electron Beam Melted Aluminum Alloys
Authors: Schaefer R. J. , Coriell S. R. , Mehrabian R. , Fenimore C. , Biancaniello F. S.
Published: March 2011

For constant velocity solidification, morphological stability theory delineates the temperature gradients required for plane front solidification of a specific alloy. Using electron beams, surface heating of metals can be carried out with sufficiently well characterized thermal input to permit reliable use of computer models of melting and solidification. From numerical calculations, the growth velocity and temperature gradients as a function of position during resolidification can be obtained; combining these results with (constant velocity) morphological stability theory indicates the resolidification regimes for which the plane front is unstable. Presumably, completely planar solidification may be attained by selecting heating modes such that the region of instability is totally avoided, but the expected interface morphology is more difficult to predict if the interface passes briefly through an unstable region and then re-enters a region of stability. Aluminum-silver and aluminum-manganese alloys were melted under an electron beam with particular emphasis on attaining solidification sufficiently rapidly to satisfy the gradient-independent absolute stability condition. It was found that the velocities required to produce stability were considerably larger than expected.