bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hard Coatings
Authors: Bull S. J. , Rickerby D. S. 
Published: March 2011

ABSTRACTThin ceramic coatings have been used in tribological applications for some time because their high defect densities and small grain size leads to a very hard, wear-resistant surface. However it is not sufficient to look at properties such as hardness in isolation when considering the selection of a coating for a given engineering application as other properties such as residual stress or adhesion may be equally important. In fact it is central to the continued development of advanced coating technologies to understand the inter-relationship between the important properties of the coating/substrate system (residual stress, hardness, adhesion etc.) and coating microstructure particularly as this can be controlled to a certain extent by the choice of deposition technology and processing parameters. By using PVD titanium nitride as an example, this paper reviews the potential for microstructural control using current physical vapour deposition (PVD) processes and shows how the microstructure of the coating is important in dictating its mechanical properties. These properties and others which still need to be measured are discussed and the potential for designing with coatings assessed in the light of current understanding.
Photoreflectance Characterization of Silicon Films on Insulator
Authors: Giordana Adriana , Glosser R. , Pellegrino Joseph G. , Qadri S. , Twigg M. E. , Richmond E. D. , Joyner Keith , Pollack Gordon 
Published: March 2011

ABSTRACTPhotoreflectance (PR) was used to study crystalline quality and stress in silicon films on insulator. The position and amplitude of the 3.4 eV PR silicon structure was monitored for both MBE silicon on sapphire (SOS) and SIMOX structures. The SOS film thicknesses ranged from 6 to 4000 nm. The shift in energy of the 3.4 eV structure from its bulk position is dependent on the sample thickness and on the strain in the films. In the SIMOX case, the amplitude of the 3.4 eV PR signal provided information about the crystalline quality of the top silicon layer for a set of six samples, each one removed at a different step of a process involving three implantation-anneal cycles. In this case the PR signal appeared to deteriorate with the each cycle undergone by the samples. Further investigations are needed to resolve the discrepancy bet ween these SOS results and the ones obtained in an earlier set of measurements.
A Vibrational Technique for Stress Measurement in Films
Authors: Jagota A. , Mazur S. , Farrisf R. J. 
Published: March 2011

ABSTRACTThis paper presents a new technique for the measument of stress in films based on the classical theory of membrane vibrations. The specimens for vibrational analysis are prepared by removing a circular or square piece of the substrate far from any edge of the film (this operation preserves the state of stress in the film). The specimen is mechanically excited by random noise and its natural frequencies are peaks in the measured response of the membrane. The natural frequencies increase as the square root of stress in the film. The only material parameter needed to determine stress from the natural frequency is the density of the film. The technique has been used to measure stress in two different systems: urethane cured epoxies and silver films under different environmental conditions (temperature and humidity).
Analysis of Stress Variations in Epitaxial Films Using Cathodoluminescence Microscopy and Spectroscopy
Authors: Yacobi B. G. , Sheldon P. 
Published: March 2011

ABSTRACTThis paper presents experimental results of a new application of cathodoluminescence microscopy in the analysis of stress variations in epitaxial layers. Cathodoluminescence microscopy and spectroscopy techniques, in conjunction with the known behavior of the optical transitions in the presence of stress, can be effectively used for both the qualitative and quantitative analyses of spatial variations of stress in epitaxial films.
Non-Destructive Assessment of Thin Film Stresses and Crystal Qualify of Silicon on Insulator Materials with Raman Spectroscopy
Authors: Wolf Ingrid De , Vanhellemont Jan , Maes Herman E. 
Published: March 2011

ABSTRACTMicro Raman spectroscopy (RS) is used to study the crystalline quality and the stresses in the thin superficial silicon layer of Silicon-On-Insulator (SO) materials. Results are presented for SIMOX (Separation by IMplanted OXygen) and ZMR (Zone Melt Recrystallized) substrates. Both as implanted and annealed SIMOX structures are investigated. The results from the as implanted structures are correlated with spectroscopic ellipsometry (SE) and cross-section transmission electron microscopy (TEM) analyses on the same material. Residual stress in ZMR substrates is studied in low- and high temperature gradient regions.
Stresses in Amorphous Gd-Fe Alloy Thin Films Deposited by Magnetron Sputtering
Authors: Zhou Zhi-Feng , Zhou Qi-Gang , Fan Yu-Dian 
Published: March 2011

ABSTRACTAmorphous Gd-Fe alloy thin films were made by D.C. planar magnetron sputtering under various deposition conditions (e.g., film thickness, composition, working pressure of Ar, negative bias voltage and deposition rate). The stress, the film composition and the content of entrapped Ar in the films were measured respectively. The experimental results showed that in this case the working pressure of Ar and the negative bias voltage did not change the composition of the films, and the stresses were all compressive except for the films deposited in a very high working pressure of Ar. The origin of the compressive stress can be attributed to the atomic peening effect produced by fast neutral working gas atoms rebounded from the sputtering target. The magnitude of the compressive stress depends not only on the amount of Ar atoms incorporated in the films but also on the film microstructure such as the packing density.
The Representation of Thermodynamic Properties in Multicomponent Alloys
Authors: Ansara I. 
Published: March 2011

ABSTRACTIn addition to theoretical models which have been developped to interpret the interactions in metallic systems, polynomials of different types have been used to represent the thermodynamic properties of solution phases. Ternary and higher order systems have been described by adding the properties of the limiting binary systems, using various summation methods ; interaction parameters specific to the multicomponent systems can be derived from sufficiently precise experimental measurements.
Mathematical Representation of Size and Electronic Factors
Authors: Brewer Leo 
Published: March 2011

ABSTRACTThe relative sizes of the atoms and their electronic configurations are important factors in determining the thermodynamic properties of metallic phases. The regular solution model provides for an asymmetric excess Gibbs energy when there is a size difference, but the actual degree of asymmetry does not correspond to crystallographic sizes. This is due in part to the effect of electronic configurations upon the asymmetry of the Gibbs energy. The Hume–Rothery Rules indicate that the bcc, hcp, and ccp structures are associated with characteristic outer–shell electron per atom concentrations. The electronic factors require modification of the usual definition of internal pressure as used in the regular solution theory. Rather than using the energy of vaporization to the ground atomic state, the energy of vaporization to the valence state atom, which has the same electronic configuration as in the condensed state, is a more appropriate measure of the degree of cohesion and the internal pressure. The problems of providing mathematical expressions that accomodate the contributions of internal pressure, electronic factors, and size factors are discussed.
Coherent Phase Diagrams in the Cluster Variation Approximation
Authors: De Fontaine Didier 
Published: March 2011

ABSTRACTCoherent phase diagrams are defined as pertaining to equilibria between phases which differ from one another merely by the distribution of different types of atoms on fixed crystallographic sites. Resulting ordered structures must then all be superstructures of one parent lattice, and corresponding phase diagrams are isomorphous to those of the Ising model with non–vanishing magnetic field. Rather complex phase diagrams can then be obtained from a single free energy functional by means of the cluster variation method. Calculated phase diagrams will be shown for the case of the fcc parent lattice with various positive and negative ratios of the values of second-to-first-neighbor pair interactions, this ratio being the only parameter which enters the calculation. Results will be compared to those of Monte Carlo calculations. The possibility of performing these first-principle calculations of coherent phase diagrams will be briefly touched upon.
Phase Stability in Rapidly Solidified Iron and Nickelrease Alloys
Authors: Wood John 
Published: March 2011

ABSTRACTThe structure of a large ranqe of model steels and high speed steels after rapid solidification are described in terms of the effect of processing conditions and alloy content. General lessons are deduced for these structures regarding the stability of austenite, ferrite, ′ and ɛ martensite, and excess carbon concentrations in rapidly solidified steels and these are compared with other workers' results. Some preliminary data regarding the structure of model nickel alloys are presented in order to shed light on previously described structures of nickel superalloys.
Hydrogen Solubility in Pd100-xSix Metallic Classes and the Phase Diagram of Pd-Si-H Glasses
Authors: Finocchiaro R. S. , Tsai C. L. , Giessen B. C. 
Published: March 2011

ABSTRACTThe hydrogen solubility of glassy Pdl00-xSix alloys with 14≤x≤22 has been measured in the temperature range of 10°C to 90°C and the hydrogen partial pressure range of 0 to 100 torr. The absorption of hydrogen in these glassy alloys is exothermic and Sieverts' law is not observed. An isothermal-isobaric ternary phase diagram showing the change of hydrogen solubility with silicon concentration is given. A preliminary analysis suggests that the hydrogen solubility is related to the atomic structure of the metallic glasses.
Metallic Glass Formation Diagrams
Authors: Giessen B. C. , Whang S. H. 
Published: March 2011

ABSTRACTThe ability to predict ready glass formation (RGF) in binary alloy systems upon rapid cooling of the melt is of value both theoretically and practically. Two-dimensional maps show promise as a means of associating RGF with two system parameters which must have a combination of favorable values. In this paper, two types of glass formation diagrams are reviewed. One of these, the ΔH-r/R plot, is based on fundamental parameters which can, in principle, be derived from elemental quantities for each binary alloy system. The second type of diagram, the temperature-composition map, uses two equilibrium phase diagram features, namely reduced liquidus temperatures and reduced eutectic compositions to predict RGF. Both approaches are compared for binary alloys of Zr. The temperature-composition plot approach can be extended to predict qualitatively the RGF composition range of a given alloy system.
Superconductivity and Magnetic Order: Low Temperature Phase Diagrams
Authors: Brian Maple M. 
Published: March 2011

ABSTRACTRecent experiments on magnetically-ordered ternary and pseudoternary rare earth superconductors are briefly reviewed. Superconductivity has been found to coexist with antiferromagnetic order, but to be destroyed by the onset of ferromagnetic order at a second transition temperature Tc2∼TM, where TM is the Curie temperature. In antiferromagnetic superconductors, the antiferromagnetic order modifies superconducting properties such as the curve of the upper critical magnetic field versus temperature. In ferromagnetic superconductors, a long wavelength (∼ 102 Å sinusoidally modulated magnetic state develops in the superconducting state as a result of the superconducting-ferromagnetic interactions. The interplay of superconductivity and competing magnetic interactions in pseudoternary rare earth systems produces complex and interesting low temperature phase diagrams.
Phase Equilibria at 1173K in the Ni-Ti-Al System
Authors: Liang W.W. , Nash P. 
Published: March 2011

ABSTRACTIn a recent review of the published literature on this system it was concluded that there is a lack of experimental data in this system particularly in regions of the system with less than 75 atomic per cent of each one of the components (1). In order to provide some consistent data over a substantial range of composition an experimental determination of the phase equilibria at 1173K and from 0–50 atomic % Al is being carried out. The main experimental technique being used is quantitative electron microprobe analysis (JEOL 733) by wavelength dispersive x-ray spectrometry. In addition, x-ray diffraction is being used to establish the structures of phases present and optical metallography of cast structures to determine the fields of primary crystallization. In addition to establishing the phase equilibria at this temperature the composition range for the existence of the AlNi2Ti phase is being determined. The results thus far are compared with previous experimental data and calculated isothermal sections (2).
Cu-Pb-Sn Ternary System: Low Cu Additions to Pb-Sn- Binary System
Authors: Marcotte V. C. , Schroder K. 
Published: March 2011

ABSTRACTA portion of the Cu-Pb-Sn ternary diagram was determined experimentally. The investigation was concentrated on the high Pb corner and, to a lesser extent of alloys from Sn to the binary Pb-Sn eutectic. The experimental techniques used were thermal analysis, metallography, and electron microprobe analysis. A new technique for determining liquidus temperatures was used. For the high Pb region the proposed ternary eutectic at 0.06 Cu 0.02% SnPb (all compositions are in weight %) was not observed. For most alloys the primary crystallization phase was Cu3Sn. It was shown that Cu6Sn5 exists in the solid state; for high Sn alloys, it was observed that the addition of Pb reduced the decomposition temperature of Cu6Sn5. A ternary eutectic reaction near the binary Pb-Sn eutectic was confirmed, and the temperature of the ternary eutectic was 1°K below that of the binary eutectic. Liquidus temperatures as well as other reactions detected by thermal analysis will be presented.
Monotectic Alloy Solidification - Determination of the Liquidus Surface in the System Succinnonitrile-Ethanol-Glycerol
Authors: Grugel Richard N. , Hellawell A. 
Published: March 2011

ABSTRACTThe microstructure of alloys undergoing a monotectic reaction, Liquid I ⇆ Solid I + Liquid II, is related to the height of the liquid miscibility gap, upper consolute temperature, TC, relative to that of the monotectic horizontal at TM. It has been shown in the system Cu-Pb-Al that a transition in microstructure occurs as the temperature interval, Tc-TM, changes with composition. In order to observe the structural change directly in a transparent material, it has been necessary to determine the liquidus surface for the system succinnonitrile(S)-ethanol(E)-glycerol(G). In this system monotectic reactions in the binary S-E and S-G systems are joined by a monovariant valley and a structural transition occurs at approximately 85.6 wt. % S, 7.5 wt. % E, 6.9 wt. % G, at a ratio of 48:52 = G:E.
Alloy Chemical Comparison of the Refractory Metal - Noble Metal Phase Diagrams T5-T10 (T5 = V, Nb, Ta; T10 = Pd, Pt)
Authors: Waterstrat R. , Giessen B.C. 
Published: March 2011

ABSTRACTThe six T5-Tl0 metal alloy phase diagrams containing Pd or Pt have now all been established. The alloy phases occurring in these systems are tabulated and reviewed here with respect to their structures.
Lattice Energy Functions for Prediction of Structural Properties of Alloy Phases
Authors: Machlin Eugene S. 
Published: March 2011

ABSTRACTLattice energy functions have been used to predict various properties. The energies and volumes of formation of alloy phases, as well as the relative stabilities of competing phases are provided by a model based on Mie type interatomic potentials. The elastic constants of alloy phases are treated using a model sensitive to the quadrupole distortion of a repulsion spheroid. The properties of defects are treated using a model based on both a volume dependent contribution and an interatomic potential contribution to the lattice energy. Good predictability is obtained for all three types of lattice energy functions in their respective applications.
Structural Maps and Parameters Important to Alloy Phase Stability
Authors: Watson R. E. , Bennett L. H. 
Published: March 2011

ABSTRACTAlloy properties are often summarized on two-dimensional maps. For instance, Darken and Gurry related the terminal solubilities of alloy systems to two coordinates (the differences in electronegativities and in atomic radii of the alloy constituents). Maps are considered here which correlate the structures in which the compounds form as well as providing some indication of whether a compound forms at some given composition in the first place. This class of map involves one coordinate which is the difference in an atomic parameter (here it will be taken to be the electronegativity) while the other is an average (in this case the d band hole count). This contrasts with Darken Gurry maps and Giessen's maps related to glass-forming ability (elsewhere in this volume) where both coordinates are differences. The situation for 50/50 transition metal alloys is reviewed and results are presented for systems off 50/50 composition.
Sic Reinforced-Mosi2 Alloy Matrix Composites
Authors: Petrovic J. J. , Honnell R. E. , Vasudevan A. K. 
Published: March 2011

AbstractMoSi2 based composites possess significant potential as high temperature structural materials. The present investigation constitutes an initial study of the fabrication and properties of MoSi2/silicide alloys and SiC particle reinforced-MoSi2 /silicide alloy matrix composites. Alloying disilicides (WSi2, Nb5Si2, Ta5Si2 ) and trisilicides (Mo5 Si3, W5Si3, Nb5Si3, Ta5Si3, Ti5Si3 ) were examined. Results indicated that at the 50/50 mole % alloying level, MoSi2 formed solid solutions with the alloying disilicides. Reaction of the MoSi2 /TaSi2 alloy with SiC was observed. An initial assessment of 50/50 mole % disilicide alloy oxidation behavior suggested an oxidation resistance inferior to that of pure MoSi2.
Microstructures and Mechanical Properties of NiAl+Mo In-Situ Eutectic Composites
Authors: Subramanian P. R. , Mendiratta M. G. , Miracle D. B. , Dimiduk D. M. 
Published: March 2011

AbstractThe quasibinary NiAI-Mo system exhibits a large two-phase field between NiAl and the terminal (Mo) solid solution, and offers the potential for producing in-situ eutectic composites for high-temperature structural applications. The phase stability of this composite system was experimentally evaluated, following long-term exposures at elevated temperatures. Bend strengths as a function of temperature and room-temperature fracture toughness data are presented for selected NiA1-Mo alloys, together with results from fractography observations.
On the Flow and Creep Strength of Power Law Materials Containing Rigid Reinforcements
Authors: He Ming Y. 
Published: March 2011

AbstractInvestigation of the flow properties of materials containing rigid reinforcements has been prompted by various technological challenges concerned with high specific strength composites. The materials of interest range from metallic materials such as Al alloys, to ceramic materials such as Si3N4 and also include the intermetallics: TiAl and MoSi2. The reinforcements are typically A12O3 and SiC. The strengths of interest may be the flow strength at ambient temperature or the creep strength. The present analysis constitutes an attempt to provide estimates of either the flow or creep strength for matrices that exhibit power law deformation.
Microstructure and Mechanical Properties of Ni3Al-Ai2O3 Composites Produced by Hot Extrusion
Authors: McKamey C. G. , Lee E. H. 
Published: March 2011

AbstractHot extrusion of premixed charges of 10–20 vol% chopped A12O fiber and Ni3Al powder has resulted in composite alloys of near theoretical density. In tensile tests at room temperature, density-compensated yield strengths of some of these composite alloys are as good or better than those of as-cast Ni3Al without reinforcement; however strengths at 1000°C in vacuum are lower. The low strength at 1000°C and fine grain size (2–3/μm) suggest the presence of superplastic behavior and the accompanying diffusional creep and grain boundary sliding. This presentation discusses our findings to date and includes microstructural studies and tensile properties, both at room temperature in air and 1000°C in vacuum.
Ductility Enhancement from Interface Dislocation Sources in a Directionally Solidified β (γ + γ′) Ni-Fe-Al Composite Alloy.
Authors: Larsen M. , Misra A. , Hartfield-Wunsch S. , Noebe R. , Gibala R. 
Published: March 2011

AbstractA directionally solidified β + (γ + γ′) Ni-Fe-AI in-situ composite alloy of composition Ni50Fe30Al20 (at.%) has been used to investigate the effect of a plastically soft second phase on the mechanical behavior of a B2 ordered intermetallic alloy. This material exhibits extensive plasticity during compressive deformation at room temperature and fails in shear with extensive γ + γ′ lamellar or rod pull-out. The material also exhibits ∼10% tensile elongation to fracture at room temperature, with final fracture that includes substantial necking of the γ + γ′ lamellae or rods. Observation of slip lines and dislocation substructures discloses that the normally brittle β matrix undergoes extensive plasticity in order to deform compatibly with the more ductile γ phase. The plasticity of the β matrix is accomplished by the generation of glissile dislocations into the β matrix from the β/γ interface region and is enhanced because of a favorable β - γ orientation relationship for slip transfer. Ductility enhancement from interface-generated mobile dislocations generated from β-γ interfaces is compared to that observed in film-coated β-NiAl single crystals and FeAl polycrystals.
Development of Highly Impact Resistant NiAl Matrix Composites
Authors: Nardone Vincent C. , Strife James R. , Prewo Karl M. 
Published: March 2011

AbstractThe ability to produce a NiAl intermetallic base composite with dramatically higher energy absorption capability and damage tolerance has been demonstrated. The approach consists of incorporating continuous tubular 304 stainless steel toughening regions throughout the NiAl matrix. To compensate for the increase in density resulting form the 304 stainless steel, B4C particulate was added to the NiAl so that the overall composite density was within 5% of the value for monolithic NiAl. The notched Charpy impact energy absorption of the B4C/NiAl/304 composites was in the range of 15 to 90 J/cm2, compared to a value of 0.8 J/cm2 for NiAl. The higher energies were measured on samples that deflected the crack front more extensively during failure. For a given interfacial condition, the energy absorption increased as the wall thickness of the 304 tubular toughening regions increased. Finally, room temperature tensile testing of the composites resulted in very large failure strains (20–35%) owing to the 304 stainless steel being able to sustain the applied load once the NiAl regions had completely cracked.