bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation behaviour, microstructure and processing of accumulative roll bonded aluminium alloy AA6016
Authors: Topic Irena , Höppel Heinz Werner , Göken Mathias 
Published: December 2013

Abstract
The technologically relevant aluminium alloy AA6016 was successfully processed using accumulative roll bonding to 8 cycles (∊von Mises = 6.4) in order to obtain an ultrafine-grained microstructure with an average grain size of approximately 200 nm. With the aim of optimising the accumulative roll bonding process detailed investigations on the robustness, the type of rolling mill, the influence of temperature, the microstructural evolution and the mechanical properties have been carried out. Processing at 230 °C provided a good compromise between thermal stability and interlamellar bonding. Samples strained up to 6 cycles (∊von Mises = 4.8) showed an increase in the yield strength by a factor of 3 in comparison to the as-received material. The ductility of the roll bonded samples was slightly sacrificed, although an increase in ductility can be achieved by increasing the number of accumulative roll bonding cycles. The mechanical properties depend on the strain rate, as has also been found for many other ultrafine-grained materials. Annealing of ultrafine-grained samples revealed a stability limit of approximately 200 °C.
Ultrafine-grained materials: a personal perspective
Authors: Langdon Terence G. 
Published: December 2013

Abstract
The Chinese philosopher Lao Tzu wrote that “a journey of a thousand li begins with a single step”.† My first step on the road to ultrafine-grained materials occurred on 5 May, 1989, when I boarded a plane in Los Angeles on the way to Ufa via Copenhagen and Moscow. This review provides a very brief summary of the historical development of ultrafine-grained materials and my personal journey through this important area of materials research.
Getting accurate nanoindentation data from time-dependent and microstructural effects of zinc
Authors: Tohid Reza R. , Bull Steve J. 
Published: December 2013

Abstract
The main objective of this study was obtaining accurate data from nanoindentation experiments on zinc. Nanoindentation experiments can be performed under displacement control, load control, or open loop conditions at different loading/unloading rates. All the above control schemes and range of loading rates were used to test pure zinc samples with different surface preparation using a Hysitron Triboindenter fitted with a blunt Berkovich indenter. The results showed that displacement control with a high loading/unloading rate gave the most reliable results. However, because of the anisotropy of zinc and its large grain size the material should be considered as a single crystal on the scale of the impression generated. It has been found that using the feedback control of nanoindentation experiments can give a significant improvement in the results compared to open loop control due to the time-dependent behaviour of zinc. A full factorial design of experiments approach was performed to investigate the optimum combination of the feedback parameters to obtain accurate and reliable data for the hardness and Young's modulus of zinc.
Nanomechanical characterization of relaxation processes in As–S chalcogenide glasses
Authors: Trunov Michael , Nagy Peter M. , Dub Sergey , Kalman Erika 
Published: December 2013

Abstract
Nanoscale mechanical properties of As – S binary chalcogenide glasses for bulk and thin-film samples have been studied, using the nanoindentation technique for a step loading procedure. All components of glass deformation (plastic, elastic. and visco-elastic, or retarded) have been evaluated during the nanoindentation process. An essential redistribution of these components was observed during unloading depending on the composition of the glasses. The same nanoindentation procedure was applied to bulk, as-deposited and annealed thin-film samples of the glasses. Plots of deformation components vs. As concentration (or average covalent coordination number <r>) show a minimum around the As25S75 – As30S70 composition (<r> ≈ 2.30), which corresponds to the rigidity percolation composition, i. e., the transition from the floppy phase to the intermediate one.
Nanomechanical studies of ultrathin polymeric resist films
Authors: Koszewski Adam , Gorski Tomasz , Reuther Freimut , Rymuza Zygmunt 
Published: December 2013

Abstract
An atomic force microscope with a specially constructed stiff cantilever was used to study the mechanical properties of ultrathin polymeric resist films devoted to use in nanoimprint lithography. The methodology, the equipment used in these studies and the results of the estimation of the Young's modulus versus temperature are presented and discussed.
Area function calibration in nanoindentation using the hardness instead of Young's modulus of fused silica as a reference value
Authors: Schiffmann Kirsten Ingolf 
Published: December 2013

AbstractFor nanoindentation hardness and Young's modulus measurements the area function of the indenter has to be calibrated carefully since direct measurement of the contact area is not possible. Most often this is done by making a series of indentations into a material with known Young's modulus, e. g. fused silica. In this paper it will be shown that this method may lead to significant deviations in hardness values found over the lifetime of the indenter due to successive rounding of the tip. Additionally, depth-dependent hardness values may apparently be found which would falsify all hardness determinations. Using instead the hardness of fused silica as a reference value these problems will be avoided. Additionally, the calibration becomes independent of material constants such as the Young's modulus of the diamond tip and the Poisson ratios of both indenter and sample, which enter into the conventional calibration method.Finally, this paper discusses whether the indentation modulus determined by nanoindentation and the Young's modulus determined by, for example, tensile testing, are quantitatively equal. This is a precondition for the traceability of the Young's modulus method often mentioned as its main advantage.
Unusual architecture of the exceedingly tough Macadamia “nut”-shell as revealed by atomic force microscopy and nanomechanics
Authors: Naimi-Jamal M. R. , Kaupp G. 
Published: December 2013

Abstract
Unlike previous assumptions, the 3D microscopic construction of the macadamia wooden shell (a model for bionics' design) is far from being “isotropic”. The consequences for the exceedingly high toughness towards cracking are investigated by atomic force microscopy to evaluate the vertical stiffeners in a fullerene-type surface architecture of the only 160 μm thick hardshell that is known to withstand up to 2000 N compressive load. Nanoindentations provide hardness and elasticity modulus at stiffeners and more compliant polygon material, as well as differences of indentation coefficients and work of indentation. Nanoscratching provides scratch coefficients and specific full scratch work values that can be compared with varied other materials using interpolations with linear relations between nanomechanical parameters. A particular lotus-type effect is found for the macadamia hardshell surface.
On the precipitation processes in commercial QE22 magnesium alloy
Authors: Lambri Osvaldo Agustin , Cuello Gabriel Julio , Riehemann Werner , Lucioni Jose´ 
Published: December 2013

Abstract
Electrical resistivity measurements, differential thermal analysis, mechanical spectroscopy and small angle neutron scattering studies have been performed on commercial QE22 magnesium alloy. The aim of this work is to resolve the appearance of Guinier – Preston zones and also to survey the small angle neutron scattering technique for various temperatures in this alloy. The coupling of all the employed experimental techniques in this work is crucial for detecting the precipitation of the Guinier – Preston zones. This is due to the strong changes in the microstructure produced by the main precipitation process, which starts at about 440 K and ends at about 640 K. We found that the temperature at which Guinier – Preston zones start to grow is about 473 K and that the dissolution temperature is 537 K.
Thermal diffusivity measurements of some industrially important alloys by a laser flash method
Authors: Abas R. Abdul , Hayashi M. , Seetharaman S. 
Published: December 2013

Abstract
In the present work, thermal diffusivity measurements of three industrially significant alloys, viz. 90Ti.6Al.4V, stainless steel with 25Cr and 6Ni as well as plain carbon steel with 0.7 % carbon have been carried out as a function of temperature. The aim of this work is to study the effect of temperature and microstructure on the thermal diffusivities of these alloys. For the 90Ti.6Al.4V alloy, thermal diffusivity increases with temperature below 1225 K. Above this temperature, the values started decreasing probably due to the dissolution of Ti3Al intermediate phase in the matrix, which would result in an increase in the disorder of the structure. For 25Cr: 6Ni stainless steel, the thermal diffusivity is nearly constant up to about 700 K. Above this, there is an increase in the thermal diffusivities with temperature during the heating cycle, which was reproducible during thermal cycling. On the other hand, the slope of the curve increases above 950 K.
In the case of the 0.7 % carbon steel, the thermal diffusivity shows a decreasing trend with temperature below the Curie point for the alloy, where the alloy consists of bcc + fcc phases. Above this point, only the fcc phase is prevalent and the thermal diffusivity was found to increase with temperature. Heat transfer is carried out by lattice vibration (phonons) as well as electrons. The contribution of electrons varies depending upon the type of alloy. In this study, the highest electron contribution was found in 0.7 % carbon steel, while the lowest was in stainless steel. The thermal conductivity values of these alloys are in good agreement with the calculated values using the model proposed by Mills.
Modelling of the β → α + β transformation in a metastable β Ti alloy based on the growth kinetics and the morphology of the α plates
Authors: van Bohemen Stefan M. C. , Laars Menno van der , Sietsma Jilt , Zwaag Sybrand van der 
Published: December 2013

AbstractThe kinetics of the isothermal β → α + β transformation in a metastable β titanium alloy has been studied by dilatometry. Based on thermodynamic aspects, the volume diffusion of Mo in the titanium matrix ahead of the interface, the interface mobility, and the morphology of the primary α plates, a transformation model is developed, which incorporates mixed-mode behaviour of the transformation in the initial stage. Fraction curves are calculated based on the simulated growth of a typical α plate within the β phase having a volume determined from the nucleus density. For comparison, fraction curves are calculated using a three-dimensional model of the β grain in which a number of plates are simulated to grow with purely diffusion-controlled kinetics. It is shown that the calculated growth rate with the mixed-mode transformation model gives a better representation of the growth rate at the start of the transformation than the purely diffusion-controlled model.
Assessment of creep rupture life of weldments of martensitic steels
Authors: Roos Eberhard , Maile Karl , Klenk Andreas , Bauer Mathias 
Published: December 2013

Abstract
Martensitic steels are of major importance for modern high efficient power plants. Their long-term creep rupture characteristics are essential for the economic and reliable design of high temperature components. However, the weldments in such components have to be considered as a potential failure area under long-term creep loading as the heat affected zone of ferritic creep resistant materials (for example new martensitic steels) is exposed to significant microstructural changes due to the heat input during welding. Furthermore, the stress situation and multiaxiality of the stress state in the weld region changes permanently due to creep and relaxation. Evaluation therefore has to be based on experimental investigation that means uniaxial creep tests of crossweld creep specimens. The microstructrural characterisation of the heat affected zone and the comparison with the situation in the optimised base material has also to be taken into account. Heat affected zone simulation of specimens and the relevant experimental investigation deliver an important basis for the modelling of the stress – strain situation. All these aspects have to be combined in the inelastic computation in order to consider all relevant effects: the individual creep strength in the different regions of the heat affected zone as well as the influence of the subsequent state of stress multiaxiality.
The paper highlights recent and on-going research activities in Germany in this domain. It also demonstrates the importance of inelastic calculation for the design of welded pipes.
Characterization of amorphous Nb oxide and its influence on Mg hydrogen sorption
Authors: Brum Mariana C. , da Conceição Monique O. T. , Guimarães Claudinei S. , dos Santos Dilson S. , Dias Marcos L. 
Published: December 2013

Abstract
Amorphous Nb2O5 was synthesized by combining niobium ethoxide with an amine surfactant. The material turned out to have a high surface area, 287 m2 g−1, and a homogeneous structure. The material was shown to be amorphous despite the heat treatment performed within a range of 150 to 550°C. The surface area of Nb2O5 reduced to 105 m2 g−1 after heat treating at 350°C. The activation energy of the Nb2O5 crystallization reaction was found to be 327 kJ mol−1. The surface area of Nb2O5 reduced significantly with heat treatment but it still improved the hydrogen kinetics since the desorption rate was 1.5 wt.% min−1. The addition of a small amount of amorphous Nb2O5 to magnesium hydride, throughout milling, helped overcoming limitations inherent to solid hydrogen storage.
Metallographische Untersuchungen an Verbundstrukturen aus Aluminiumschaum mit thermisch aufgespritzten Schichten
Authors: Maurer Matthias , Koch Dieter , Zhao Lidong , Lugscheider Erich 
Published: December 2013

Kurzfassung
Aluminiumschäume stehen an der Schwelle industrieller Anwendungen. Viele neue Einsatzgebiete können für diese neuen Werkstoffe gefunden werden, wenn sich eine definierte, verschleiß- und korrosionsbeständige Oberfläche einstellen lässt. Dies ist sehr gut mit den Verfahren des thermischen Spritzens möglich. Die metallographische Beurteilung dieser Verbunde ist sehr anspruchsvoll, da die teils sehr harten Schichten gänzlich andere Eigenschaften aufweisen als der sehr weiche und großporige Aluminiumschaum. Im folgenden Artikel werden die Aluminiumschäume sowie die zur Veredelung verwendete Spritztechnik kurz vorgestellt; den Schwerpunkt bilden eine angepasste metallographische Präparation sowie Probleme, die hierbei auftreten können.
Einfluss von Lüdersbändern auf die Schwingfestigkeit von Proben unterschiedlicher Geometrie aus einem normalgeglühten Stahl Cm15
Authors: Laue Sascha , Bomas Hubert , Mayr Peter 
Published: December 2013

Kurzfassung
Bei der Verformung normalgeglühter Stähle treten bei Überschreitung der Streckgrenze Lüdersbänder auf, deren Ausprägung in starkem Maße von der verwendeten Probengeometrie abhängig ist. Mit der Entstehung und Ausbreitung geht eine starke Veränderung der Oberflächentopografie einher, die eine bei Umformprozessen meist unerwünschte Oberflächenstruktur hervorruft. Auch bei zyklischer Beanspruchung kann es zur Bildung und Ausbreitung von sogenannten Ermüdungslüdersbändern kommen, die eine Veränderung des Oberflächenzustands bewirken und somit die Schwingfestigkeit beeinflussen. Dieser Beitrag zeigt auf, wie sich unterschiedliche Probengeometrien aus einem normalgeglühten Stahl Cm15 bei einsinniger Verformung verhalten und welche Konsequenzen sich aus diesem Materialverhalten für eine zyklische Beanspruchung ergeben.
Quantitative Bestimmung der Gefügeinhomogenität bei richtungsabhängiger Partikelverteilung
Authors: Öchsner Andreas , Gegner Jürgen , Grácio José J.A. 
Published: December 2013

Kurzfassung
Die Charakterisierung und quantitative Analyse inhomogener diskontinuierlicher Gefüge stellt wegen der hohen Relevanz für technische Legierungen, insbesondere in den Bereichen Qualitätskontrolle und Eingangsprüfung, eine praktisch wichtige Aufgabe der Metallographie dar. Repräsentative eindimensionale Modellverteilungen bilden darüber hinaus Eingabedaten für Simulationsrechnungen beispielsweise von diffusionsgesteuerten Prozessen in der Wärmebehandlungstechnologie oder der Charakterisierung von Porenverteilungen im Rahmen der Schädigungsmechanik. Die vorliegende Arbeit erläutert ein Verfahren zur Charakterisierung inhomogener Teilchenanordnungen auf Grundlage der digitalen Bildanalyse metallographischer Schliffaufnahmen. Es wird ein geeigneter Parameter zur Gefügebewertung vorgeschlagen. Durch ein einfaches Berechnungsverfahren kann eine realistische eindimensionale Modellverteilung abgeleitet werden. Die Methode wird beispielhaft auf Wälzlagerstahl 100Cr6 angewandt.
Analysis of NiO and CeO2 Buffer Layers foir YBCO Coated Conductors on Textured Ni Substrates
Authors: Park Hai-Woong , Kim Chan-Joong 
Published: December 2013

Abstract
NiO and CeO2 buffer layers for YBa2Cu3O7 (YBCO) coated conductors were deposited on biaxially textured Ni substrates by a metal-organic chemical vapor deposition(MOCVD). The Ni tape substrate was fabricated by sintering of Ni powder at 1100°C for 6h, and cold-rolled into thin tapes. The subsequent heat treatment of the Ni tape at 1000°C resulted in (200) texture development. The surface conditions of the coating layers were characterized as a function of the oxygen partial pressure (PO2) and deposition temperature. According to the Atomic Force Microscopy and SEM results, the average surface roughness of NiO was in the range of 3.1 4.6 nm which was much smoother than that prepared by an oxidation method. In the case of CeO2 films, the surface roughness was kept less than 15 nm up to the deposition temperature of 500°C, but it rapidly increased at T = 520°C due to rapid grain growth of the CeO2. The (200) texture of CeO2 was formed at T=500°C-520°C, t = 3–15 min and PO2=2.30 torr.
Schadensanlyse an einer gebrochenen Hebevorrichtung
Authors: Zgraggen Markus , Piskoty Gabor , Winkler Rolf , Trüllinger Samuel , von Trzebiatowski Oliver 
Published: December 2013

Kurzfassung
Gebrochene Aufhängevorrichtungen für Betonplatten, die aus einem Baustellenunglück stammen, wurden einer Schadensanalyse unterzogen. Dabei konnte mittels fraktographischer Methoden nachgewiesen werden, dass die Aufhängungen spröde Gewaltbrüche im Bereich der Schweissnähte aufwiesen. Metallographisch konnten Aufhärtungen und Risse in der Wärmeeinflusszone nachgewiesen werden. Die rechnerische Überprüfung der Bauteile hat ergeben, dass im Baustellenbetrieb unzulässig hohe Beanspruchungen aufgrund einer ungünstigen Konstruktionsweise aufgetreten sind. Bei einem intakten Werkstoffzustand würden sich Überbelastungen durch plastische Deformationen bemerkbar machen, welche im vorliegenden Fall aufgrund der Kerbwirkung und damit verbundener mehrachsiger Spannungszustände aber in einem Sprödbruch geendet hatten. Die Untersuchung hat zum Ergebnis, dass die Konstruktion primär aufgrund eines Schweissfehlers versagt hat. Wegen falscher Werkstoffwahl kam es zu Aufhärtungen, Rissbildungen und damit verbundenen Versprödungen in den Wärmeeinflusszonen der Schweissungen.
Vermessung und Bewertung der Oberflächentopographie von Mikrobauteilen
Authors: Horsch Christoph , Schulze Volker , Löhe Detlef 
Published: December 2013

Kurzfassung
Tastschnittgeräte, wie sie üblicherweise zur Rauheitsmessung verwendet werden, sind zur Oberflächenanalyse von Mikrobauteilen nur sehr eingeschränkt einsetzbar. Die Verwendung der konfokalen Weißlichtmikroskopie als berührungsloses optisches Messverfahren zur Topographievermessung von Mikrobauteilen wird vorgestellt. Da die herkömmlichen Rauheitsnormen bei Mikrobauteilen aufgrund der kurzen verfügbaren Messstrecken an die Grenze ihrer Anwendbarkeit stoßen, wird ein neuer Rauheitsparameter für Mikrobauteile vorgeschlagen.
Darüber hinaus wird die Vermessung von Formelementen an Mikrobauteilen mittels konfokaler Weißlichtmikroskopie vorgestellt.
Dünne Bänder aus CuAlNi-Formgedächtnislegierungen hergestellt durch Melt-Spinning
Authors: Unterweger Elfriede , Lojena Gorazd , Kneissl Albert C. , Anžel Ivan 
Published: December 2013

Kurzfassung
Die Verwendung von Formgedachtnislegierungen fur Mikroaktuatoren stellt ein potentielles Anwendungsfeld dar, wobei hier neben den Nickel-Titan-Legierungen auch Legierungen auf Kupfer- Basis ihre Einsatzmoglichkeiten finden, da diese hohere Schalttemperaturen erreichen konnen und kostengunstiger sind.
Im Rahmen dieser Arbeit wurden dunne Bander aus CuAlNi-Legierungen durch Melt-Spinning hergestellt. Mittels dieses Verfahrens konnen durch geeignete Wahl der Prozessparameter Bander mit einer Dicke im Bereich von 50–250 μm produziert werden. Die Untersuchung des Gefuges und der Struktur erfolgte mit herkommlichen Untersuchungsmethoden. Problematisch war hier vor allem die Probenpraparation aufgrund der geringen Groöe der Proben. Die Umwandlungstemperaturen wurden durch DSC-Messungen bestimmt. Ein nachfolgendes Walzen konnte die Oberflachenbeschaffenheit und Homogenitat der Bander im Hinblick auf die Dicke entscheidend verbessern.
Microstructural Investigation of Hard Phases in As-Cast Ni-Ti Memory Alloy
Authors: Raz Sadegh Badakhshan , Sadrnezhaad S. K. 
Published: December 2013

Abstract
Ti4Ni2O, Ti4Ni2N, TiC and Ti2Ni are brittle compounds usually formed during production and processing of the Ti-Ni SMA alloys. These compounds adversely affect on workability and shape memory properties of the alloy. This paper presents most recent findings related to the morphologies of various inclusions and Ti-Ni phases formed during and after vacuum induction melting and casting of Ti-45wt.% Ni material. Cast samples were mechanically and/or electrolytically polished and etched. Extensive optical and scanning electron microscopic studies were carried out to characterize the composition and microstructure of the as cast Ti-Ni alloys. Results indicated that mechanical polishing followed by etching was not proficient to reveal sufficient data on physical specifications and morphological changes of the born brittle oxide and nitride and carbide phases. An innovative set of electropolishing/etching conditions was, therefore, prescribed to yield detailed information on morphologies of the brittle phases. Experimental conditions were devised for characterization of the Ti2Ni precipitates, as well.
The Effect of Micro-Alloying Addition of Ca and Ma on Castability and Performance of Mg-Based Sacrificial Anodes
Authors: Wielage B. , Mücklich S. 
Published: December 2013

Abstract
Castability and electrochemical properties of the as-cast Mg-alloys, i.e., Mg-Xwt%(X=0.22∼1.31)Ca alloy, Mg-Xwt%(X=0.24∼0.26)Mn-Y wt% (Y=0.10∼0.14)Ca alloys were evaluated. Out of these alloys, the Mg-0.26wt%Mn-0.14wt%Ca alloy shows the highest efficiency and lowest open-circuit potential. Flow length of the specimens decrease with an increase of Ca content. Serious decrease of flow ability in Mg melt is observed in Mg-1.31wt%Ca alloy. However, flow length of Mg-Ca alloys is negligibly influenced by small amounts of Mn addition. The improved performance of Mg-Ca alloys, regardless of Mn addition is attributed to the homogeneous and refined microstructures, extremely electronegative potential of Ca. It is considered from that serious reduction in flow reduction of Mg-1.31wt%Ca alloy is due to cast from large solidification interval.