bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Glass Composition on Mechanical Properties of Interfaces Between Alumina and Silicate Glass
Authors: Zagrebelny Andrey V. , Lilleodden Erica T. , Barry Carter C. 
Published: April 2011

ABSTRACTInterfaces between glass and crystalline grains have been examined using a thin-film geometry which allows the use of newly developed experimental methods for micromechanical testing of interfaces. In this approach, continuous films of thicknesses ranging 100–200 nm of anorthite (CaAl2Si2O8), celsian (BaAl2Si2O8), and monticellite (CaMgSiO4) are deposited onto single-crystal Al2O3 (α-structure) surfaces of different crystallographic orientations by pulsed-laser deposition (PLD).Mechanical properties such as hardness, stiffness, and reduced Young's modulus were probed with a newly developed high-resolution depth-sensing indentation instrument. Emphasis has been placed on examining how changes in the glass composition will affect the mechanical properties of the single-crystal Al2O3/silicate-glass interfaces. The indentation data obtained from these experiments correlate directly to the morphology of the deformed regions imaged with atomic force microscopy (AFM). Nanomechanical tests combined with AFM imaging of the deformed regions allow force-displacement measurements and in-situ imaging of the same regions of the specimen before and immediately after indentation. This new technique eliminates the uncertainty of locating the indenter after unloading.
Atomistic Simulation of Grain Boundary Structure and Diffusion in B2 NiAl
Authors: Mishin Yuri , Farkas Diana 
Published: April 2011

ABSTRACTUsing embedded atom potentials and molecular statics we calculate the structure and energy of [001] tilt grain boundaries in NiAl for 25 orientations with Σ values from 5 to 185. For three structures (stoichiometric, Ni-rich and Al-rich) of the Σ = 5 (210) boundary we simulate tracer self-diffusion by the vacancy mechanism both parallel and perpendicular to the tilt axis using the Monte Carlo technique. The effective activation energy calculated in a wide temperature range is compared with the spectrum of individual jump energies in the boundary core. The results are interpreted in terms of the grain boundary structure-diffusion relationship and the role of the jump correlation effect in grain boundary diffusion.
Grain Rotation and Grain Boundary Selection in Thin Films
Authors: Singh Varun , King Alexander H. 
Published: April 2011

ABSTRACTComputer simulations of the phenomenon of grain rotation in polycrystalline <111> textured films have been carried out. These simulations provide insight into the evolution of film microstructure due to grain rotation. It is found that grain rotation diminishes with annealing time and stops almost completely when a metastable equilibrium is obtained. The incidence of Σ1, Σ7 and Σ3 Coincident Site Lattice (CSL) boundaries increases with time while the other CSLs reduce in number. Sequential annealing experiments have been performed on thin films of gold. Grain rotation is found to take place with an average rotation rate of about 4°/hour at both 250°C and 350°C.
Diffusion Barrier Effect of Carbide Layer on Bonding Characteristics of Ti/Steel Clad
Authors: Morizono Y. , Nishida M. , Chiba A. 
Published: April 2011

ABSTRACTBonding characteristics and interfacial microstructures in explosively welded Ti/stainless steel clad of the as-welded and annealed states were investigated. In case of Ti/SUS430 ferritic stainless steel combination, the average shear strength of an as-welded clad was 555 MPa, and metastable phases such as amorphous and fine crystalline phases were observed at the interface. These were considered to be the trace of melting and subsequently rapid solidification at the contact surface of both the parent materials. By annealing below 1173 K, the strength gradually decreased with increasing holding time. The average shear strength of the clad annealed at 1073 K for 360 ks was 242 MPa, while that of the clad annealed at 1273 K abruptly decreased down to 107 MPa with increasing holding time up to 360 ks. The reaction layer formed at the interface consisted only of TiC in the former. On the other hand, the coexistence of TiC, TiFe, TiFe2 and χ was observed at the interface in the latter. The TiC in the former was considered to serve as a barrier for diffusion of Ti, Fe and Cr across the interface and to suppress the formation of intermetallic compounds. As a result, the growth of reaction layer was inhibited and high bonding strength was preserved even after prolonged annealing. The results of the Combination of Ti and SUS304 austenitic stainless steel were also discussed.
Structure and Mechanical Properties of Titanium Nitride, Zirconium Nitride, and Chromium Nitride Films by Reactive Magnetron-Sputter Deposition
Authors: Soe W.-H. , Kitagaki T. , Ueda H. , Shima N. , Otsuka M. , Yamamoto R. 
Published: April 2011

ABSTRACTTiN, ZrN, and CrN films were grown by reactive magnetron sputtering on WC-Co sintered hard alloy substrates. Hardness and elastic modulus were measured by nano-indentation tester with low load on tip at 200 mgf. Hardness values were shown the higher value the thinner film thickness due to stress in the films.
Mechanisms of Oxygen and Water Diffusion Through Multilayer Inorganic/Organic Coatings
Authors: Tropsha Yelena G. , Harvey Noel G. , Graper Jane C. 
Published: April 2011

ABSTRACTPolyethyleneterephthalate substrates were coated with thin films of silicone oxide deposited by magnetically enhanced chemical vapor deposition. The rates of oxygen and water vapor transport through the coated and uncoated film systems were obtained as a function of temperature. Activated rate theory treatment of oxygen transmission rates revealed that silicone oxide coatings were imperfect; the apparent free energies of activation (ΔEp) for transport through film substrates which were coated on a single side were statistically identical to uncoated controls. However, multilayer coatings, consisting of two silicone oxide layers separated by an organic layer resulted in a dramatic increase in the ΔEp value. Similar effects were observed in polymer films coated on both sides with identical oxide layers. A simple empirical model for the change in transport mechanism is offered to explain this unanticipated results.Activated rate theory treatment of water vapor transmission rates for these same film systems showed no obvious change in transport mechanism. However, ΔEp values obtained for water vapor permeation through silicone oxide coated polyethyleneterephthalate, polystyrene, polypropylene, and polycarbonate substrates were identical within experimental error, suggesting attractive interaction between the oxide layer(s) and water.
Links Between the Interface Plane Scheme and Grain Boundary Properties
Authors: Randle Valerie 
Published: April 2011

ABSTRACTThis paper describes the current experimental knowledge base concerning the geometry and property relationships at the gram boundary plane. In order to analyse the data the interface-plane scheme is used, and its application is described here. The most important points to emerge from the data are that particular boundary properties - energy, mobility, segregation, precipitation and cracking - correlate with boundary plane types. Recent data illustrating the high occurrence of asymmetrical tilt grain boundaries and importance of low-index grain boundary planes are discussed in more detail.
The mechanism of sputter-induced orientation change in YBCO films on MgO (001)
Authors: Huang Y. , Vuchic B. V. , Baldo P. , Buchholz D. B. , Mahajan S. , Lei J. S. , Markworth P. R. , Merkle K. L. , Chang R. P. H. 
Published: April 2011

AbstractThe mechanisms of the sputter-induced orientation change in YBa2Cu3O7-x(YBCO) films grown on MgO (001) substrates by pulsed organometallic beam epitaxy (POMBE) are investigated by x-ray diffraction, Rutherford backscatter spectroscopy (RBS), cross-section TEM (XTEM) and microanalysis. It is found that the W atom implantation concurring with the ion sputtering plays an important role in effecting the orientation change. This implantation changes the surface structure of the substrate and induces an intermediate layer in the initial growth of the YBCO film, which in turn acts as a template that induces the orientation change. It seems that the surface morphology change caused by ion sputtering has only a minor effect on the orientation change.
Tailoring the Intergranular Phases in Silicon Nitride for Improved Toughness
Authors: Sun E. Y. , Becher P. F. , Plucknett K. P. , Waters S. B. , Hirao K. , Brito M. E. 
Published: April 2011

ABSTRACTIntergranular glass phases can have a significant influence on the fracture resistance (R-curve behavior) of silicon nitride ceramics and appears to be related to the debonding of the β-Si3N4/oxynitride-glass interfaces. Applying the results from β-Si3N4-whisker/oxynitride-glass model systems, self-reinforced silicon nitrides with different sintering additive ratios were investigated. Silicon nitrides sintered with a lower Al2O3:Y2O3 additive ratio exhibited higher steady-state fracture toughness together with a steeply-rising R-curve. Analytical electron microscopy studies suggested that the different fracture behavior is related to the Al content in the SiAlON growth band on the elongated grains, which could result in differences in interfacial bonding structures between the grains and the intergranular glass.
Interfacial Characterization with Spectrum-Lines and Multivariate Statistical Analysis
Authors: Anderson I. M. , Bentley J. 
Published: April 2011

ABSTRACTChanges in the electron energy-loss near-edge fine structure (ELNES) of the O-K and Co-L edges have been characterized in cobalt oxide in the vicinity of a boundary between periclase-(CoO) and spinel- (Co3O4) structured phases. The data were acquired with a conventional transmission electron microscope (CTEM) equipped with an imaging filter and operated in spectrum-line mode. Independent spectral features were identified by multivariate statistical analysis (MSA) of the raw data. The MSA of the spectrum-image acquired at the Co-L edge indicated a transition over ∼12 nm in the spectral features at the phase boundary. The variation of the ELNES at the O-K edge varied appreciably only in the interface region, whereas that at the Co-L edge also indicated subtle gradients in both phases adjacent to the interface area. These gradients are consistent with a change in the average oxidation state of the cobalt cations in the vicinity of the interface. A second independent component of the ELNES was also identified at the Co-L edge. Possible interpretations of this second component are discussed.
Self-Monitoring of Strain and Damage by Carbon Fiber Polymer-Matrix Composite
Authors: Wang Xiaojun , Chung D.D.L. 
Published: April 2011

ABSTRACTSelf-monitoring of damage and dynamic strain in a continuous crossply (0°/90°) carbon fiber polymer-matrix composite by electrical resistance (R) measurement was achieved. With a static/cyclic tensile stress along the 0° direction, R in this direction and R perpendicular to the fiber layers were measured. Upon tension to failure, R in the 0° direction first decreased (due to increase of degree of 0° fiber alignment) and then increased (due to 0° fiber breakage), while R perpendicular to the fiber layers increased monotonically (due to increase of degree of 0° fiber alignment and delamination). Upon cyclic tension, R (0°) decreased reversibly, while R perpendicular to the fiber layers increased reversibly, though R in both directions changed irreversibly by a small amount after the first cycle. For a 90° unidirectional composite, R (0°) increased reversibly upon tension and decreased reversibly upon compression in the 0° direction, due to piezoresistivity.
Photo-Induced Polarization Recovery in PZT Thin Film Capacitors
Authors: Mansour S. A. , Rao A. V. , Bement A. L. , Liedl G. 
Published: April 2011

ABSTRACTLead Zirconate Titanate (PZT) ferroelectric thin film capacitors were fabricated with metallic platinum and conducting Indium Tin Oxide (ITO) contacts. PZT thin films were fabricated using metallorganic decomposition (MOD) while a combination of MOD and RF-sputtering was used in fabricating the ITO-PZT-ITO capacitors. Photo-induced changes, manifested by an increase in switchable polarization, were studied before and after 108 switching cycles fatigue using white and monochromatic light. An increase in photo-induced changes was observed at 3.65eV light energies using monochromatic light using both capacitors. The increase was attributed to the excitation of electrons from PZT valence band into the conduction band causing an increase in film conductivity. However, polarization increase in Pt-PZT-Pt capacitor was more pronounced than ITO-PZT-ITO when white light was used. Some of the response in fatigued Pt-PZT-Pt capacitors was attributed to the excitation of electrons from the platinum Fermi level to oxygen vacancy sites trapped at the Pt-PZT interface by absorption of infrared radiation of white light. The latter observation implied a relationship between PZT fatigue and photo-induced effects.
Combination of Different Methods to Characterize Micromechanical Sensors
Authors: Buchhold R. , Büttner U. , Nakladal A. , Sager K. , Hack E. , Brönnimann R. , Sennhauser U. , Schroth A. 
Published: April 2011

ABSTRACTIn the last years many micromachined sensors for measuring quite different quantities have been developed (e.g. [1][2]). The successful design of silicon micromachined sensors and their conversion into commercial products is still limited by the lack of full understanding of complex fault mechanisms. In order to detect those mechanisms it seems to be advantageous to investigate interrelated phenomena by different analysis methods. By combining results of several means the true nature of disturbing effects can be determined much more easily.This paper describes a comprehensive approach for investigating failure mechanisms in piezoresistive pressure sensors. Sophisticated methods of signal analysis were combined with special semiconductor techniques, determination of thermo-mechanical properties, Finite-Element- (FE-) simulation and Michelson interferometry. By that it was possible to separate disturbing mechanical as well as electrical effects and their relation to sensor output and sensor accuracy, respectively. In particular, we discovered complex influences of passivation layer systems (differing in geometrical and technological parameters) on sensor accuracy.
Constitutive Equation of NiTi Superelastic Wire
Authors: Yang F. , Pu Z. J. , Wu K. H. 
Published: April 2011

ABSTRACTDuring the superelastic deformation process, because of the involvement of the austenite-martensite phase transformation, a superelastic wire will experience a self-heating or self-cooling process due primarily to the latent heat of the material. As the strain rate increases, and conditions become more adiabatic, the self-heating and self-cooling will cause a temperature rise upon loading and will drop upon unloading. As a consequence, an apparent effect of the strain rate on the superelastic behavior in the shape-memory alloys with a large diameter or more adiabatic conditions will be noticed. In the present paper, a constitutive stress-strain-strain rate equation is proposed to describe the self-heating behavior. In order to verify the model, a series of experiments have been conducted to study the effect of the strain rate, wire diameter, and adiabatic condition on the superelastic behavior of the shape-memory alloy wire. As will be shown later, the proposed equation can predict the behavior of the superelastic wire accurately, and the prediction is in good agreement with the experimental data.
The Two-Way Memory Effect by Pre-Straining in a 45Ni50Ti5Cu Alloy
Authors: Airoldi G. , Ranucci T. 
Published: April 2011

ABSTRACTThe 45Ni50Ti5Cu shape memory alloy exhibits one single thermoelastic martensitic transformation from the parent B2 phase to monoclinic B19’and looks as an appealing system to be used for the two way memory effect (TWME). First results, appeared in literature, on the TWME in 45Ni50Ti5Cu indicate that in this alloy high figures for the two way strain can be obtained. The prestrain method is here investigated to imprint the TWME in a 45Ni50Ti5Cu alloy: a pseudoplastic deformation higher than the reorientation strain is applied in martensite, followed, after unloading, by a recovery of the one-way strain by heating to 110°C. The two way memory strain is detected in the following thermal cycle. Results show the two way memory strain can be imprinted in just one cycle, but it can even considerably be increased by repeating the procedure: the highest figure for the two way memory strain is however obtained whenever a plastic unrecoverable strain is accumulated in the specimen in some prestraining cycles. Often the maximum two way strain is of the same order as the plastic strain and the former decreases with the increase of the latter.
Actuator Applications with Single-Crystals of Cu-Zn-Al Shape Memory Alloy
Authors: Yawny A. A. , Sade M. , Lovey F. C. 
Published: April 2011

ABSTRACTIn the present work the use of single-crystals of Cu-Zn-Al Shape Memory Alloys (SMA) in actuator applications is analyzed. The actuator considered here, a device capable of doing work in response to temperature changes, is based on a single-crystal nucleus of a Cu-Zn-Al SMA coupled to a conventional spring that represents the load to be displaced. A special experimental stage was designed for performing controlled thermal cycles under load. In this way the effects of different parameters (cycle number, friction, temperature range, load level) on the actuator behavior can be studied. From the results obtained, the use of a single-crystal of an SMA in a thermostatic device is analyzed and compared with the commercial wax actuator performance.
Stress Evolution During Crystallization and Isothermal Annealing of Titanium-Nickel on (100) Si
Authors: Zhang Jinping , Grammon D. S. 
Published: April 2011

ABSTRACTThin films of near-equiatomic titanium-nickel are capable of thermally induced shape-strains and have recently been applied to silicon-based micromachined reversible actuators in force-production devices requiring energy-density levels substantially exceeding those available from piezoelectric, electromagnetic, electrostatic, or bimetal systems. Reversible actuation requires the presence of a resetting agent, or ‘bias’ force, capable of deforming the martensite phase during the exothermic transformation on cooling. Here, we show that both the initial martensite ‘programming’ force, and the bias force for subsequent reversible actuation, can readily be provided by manipulating intrinsic and extrinsic stresses developed during low-pressure sputter deposition of TiNi, and subsequent cooldown from either the deposition process temperature or from the crystallization annealing temperature. The stability of both intrinsic and extrinsic stresses at temperatures below the deposition temperature allows considerable flexibility in the design of the force-producing system, and reversible stress-production to levels beyond 0.7 GPa are shown to be readily achieved, corresponding to energy-density levels approaching 10 MJ-m−2. The present paper will review recent results from our group on the development of residual stresses in TiNi sputtered on (100) Si, using the wafer-curvature method applied during isochronal and isothermal vacuum annealing of both amorphous and crystalline thin films, with an emphasis on the combined influence of deposition temperature and annealing temperature on stress-relaxation rates, and on the response of the system to temperature cycling in the displacive transformation range.
The Electrical Resistance Properties of Shape Memory Alloys
Authors: Airoldi G. , Pozzi M. , Riva G. 
Published: April 2011

ABSTRACTShape memory alloys are known for their ability to build up large deformations under an applied stress, either in martensitic phase or in the pseudoelastic region.The electrical resistance of shape memory alloys, traditionally used to define the transformation temperatures, shows interesting features when considering its modification as a function of strain. The electrical resistance in NiTiCu ribbons, obtained by melt spinning, is here examined, either in martensite or in the pseudoelastic range or under a constant applied stress across the transformation range. In each examined case, the results obtained show that the electrical resistance follows a linear relationship as a function of the imprinted strain.
Shape Memory Thin Films of the System Ti- (Ni-Pd-Cu)
Authors: Quandt E. , Holleck H. 
Published: April 2011

ABSTRACTFree-standing shape memory thin films of the system Ti-Ni-Pd-Cu exhibiting the two-way-effect have been fabricated by d.c. magnetron sputtering onto unheated substrates followed by annealing and training processes. Their transformation temperatures were investigated by differential scanning calorimetry and electrical resistivity measurements. By the Ni-Pd substitution the transformation temperatures (austenite/martinsite finish temperature; Af/Mf) could be varied between 32°C/-38°C for the binary TiNi films to 570°C/498°C for the binary TiPd films. By the Ni-Cu substitution the transformation hysteresis (Af/Mf) could be reduced from 70°C for the binary film to 20°C for films with 10 at % Cu. A similar behavior was observed for TiNiPdCu films.
Radial, Planar and Helical Anisotropies Induced in Cylindrical Amorphous CoP Multilayers
Authors: Favieres C. , Caroca C. , López E. , Sánchez M. C. , Sánchez P. , Madurga V. 
Published: April 2011

ABSTRACTElectrolytic cylindrical amorphous CoP multilayers, grown on copper wires, with controlled continuos variation of the magnetic anisotropy, in both, direction and magnitude, have been produced. The inner zone of the samples has been grown to exhibit radial anisotropy and the overlayer has been obtained with planar longitudinal anisotropy. Our studies have revealed that the magnetization at the surface of the samples is strongly coupled with the bulk anisotropy for thickness of the overlayer of ≈ 1.5 μm. Furthermore, it has been found that an angular deformation applied to the samples, when the copper wire is subjected to a torsion, modifies the direction of the longitudinal anisotropy to the helical direction. Also, a large spontaneous Matteucci effect is induced by means of this angular deformation.
Magnetostrictive Composite Material Systems Analytical/Experimental
Authors: Duenas T. A. , Hsu L. , Cakman G. P. 
Published: April 2011

ABSTRACTExperimental and theoretical results are presented for a composite magnetostrictive material system. This material system contains Terfenol-D particles blended with a binder resin and cured in the presence of a magnetic field to form a 1–3 composite. Test data indicates that the magnetostrictive material can be preloaded in-situ with the binder matrix resulting in orientation of domains that facilitate strain responses comparable to monolithic Terfenol-D. Two constitutive equations for the monolithic material are described and a concentric cylinders model is used to predict the response of the composite structure. Experimental data obtained from the composite systems coincide with the analytical models within 10%. Particle size, resin system, and volume fraction are shown to significantly influence the response of the fabricated composite system.
Polarization and Piezoelectric Properties of a Nitrile Substituted Polyimide
Authors: Simpson Joycelyn , Ounaies Zoubeida , Fay Catharine 
Published: April 2011

ABSTRACTThis research focuses on the synthesis and characterization of a piezoelectric (β-CN)-APB/ODPA polyimide. The remanent polarization and piezoelectric d31 and g33 coefficients are reported to assess the effect of synthesis variations. Each of the materials exhibits a level of piezoelectricity which increases with temperature. The remanent polarization is retained at temperatures close to the glass transition temperature of the polyimide.