bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical properties and microstructural changes of ultrafine-grained AA6063T6 during high-cycle fatigue
Authors: Hockauf Matthias , Meyer Lothar W. , Halle Thorsten , Kuprin Corinna , Hietschold Michael , Schulze Steffen , Krüger Lutz 
Published: December 2013

Abstract
Fatigue behaviour and mechanical properties of peak-aged AA6063T6 with ultra-fine grain size, produced by equal channel angular extrusion, were evaluated with special emphasis on the microstructure before and after cyclic loading. The strength significantly increased with grain size reduction and is described by an exponential power-law constitutive relationship. A remarkable enhancement of fatigue life compared to commercial AA6063T6 with coarse grains was found in the high-cycle regime after the first two extrusions. Further extrusions eliminated this improvement. It is shown that the optimum fatigue performance correlates very well with the minimum tensile ductility. Electron backscatter diffraction revealed that the material behaviour can basically be attributed to the grain boundary characteristics. Low grain boundary misorientation angles yield the best fatigue performance in the ultrafine-grained microstructure.
Analysis of failure behaviour of carbon/carbon composite made by chemical vapour infiltration considering fibre, matrix and interface properties
Authors: Ermel Ralf , Beck Tilmann , Kerscher Eberhard 
Published: December 2013

Abstract
The mechanical properties of a unidirectional carbon/carbon (C/C) composite with a mainly highly textured matrix are investigated in tensile tests for the as-received state and after heat treatment from 1600°C to 2500°C. In order to interpret the composite behaviour single fibre tests, analyses of fracture surfaces and tests on infiltrated fibre felts were conducted. The fibre–matrix shear strength was determined by push-out indentation tests. Strength and ductility only change slightly although the strength of the fibres decreases significantly with increasing heat treatment temperature (HTT). The reason is a reduced bonding strength between fibre and matrix with increasing HTT. The Young's modulus of C/C composites increases with HTT. The best mechanical properties of the composite are reached by finding a compromise between sufficient fibre strength and weakened fibre-matrix strength at a HTT of 1600°C.
Grinding-induced microstructural gradients and residual stresses in the surface layers of carbon steel and pure tungsten
Authors: Okolo Brando , Wanner Alexander 
Published: December 2013

Abstract
Flat samples of AISI 1080 carbon steel and commercially pure tungsten were surface-treated using a reciprocating table-type grinding machine. Cross sections of the subsurface microstructure induced by this mechanical finishing process were prepared and imaged by focussed ion beam methods. Depth profiles of the residual normal and shear stresses were analysed using synchrotron X-ray diffraction and correlated to the observed microstructural gradients. The stress partitioning between the hard cementite and the soft ferrite phases in the ground steel samples is discussed in detail.
Damage tolerance: fracture mechanics in design
Authors: Schwalbe Karl-Heinz , Zerbst Uwe 
Published: December 2013

AbstractFracture mechanics methods are usually applied if a crack-like flaw is detected in a structural component and a decision has to be taken with respect to limited further service, or if a failure case has to be assessed. The present contribution demonstrates various options for the inclusion of fracture mechanics in the design process. A number of fracture mechanics based concepts are available; these include classical damage tolerance, proof testing, and periodic removal of cracks through grinding. Until now, less attention has been paid to application in the design stage, where, however, consistent inclusion of fracture mechanics in design promises substantial potential in designing against failure.
Polymer-derived Si–C–N ceramics reinforced by single-wall carbon nanotubes
Authors: Burghard Zaklina , Schön Davina , Garstel Peter , Bill Joachim , Aldinger Fritz 
Published: December 2013

Abstract
Nanocomposites made of polymer-derived Si–C–N ceramic reinforced by single-wall carbon nanotubes (SWCNTs) were prepared for the first time. The synthesis procedure involved ultrasonic dispersion of the nanotubes into a liquid polysilazane precursor polymer, followed by cross-linking and thermolysis. With the aid of nanoindentation testing, dependence of the mechanical properties of the composites on the concentration and agglomeration state of SWCNTs, was studied. The nanotube-filled composites showed improved mechanical performance, as reflected by an increase in Young's modulus which was found to be correlated with the microstructure of the composites, in particular the degree of dispersion of the nanotubes inside the matrix, whereas the hardness is hardly affected.
Effect of surface roughening on increasingthe spectral selectivity of cermet solarselective absorbers
Authors: Nejati M. Reza , Clasen Rolf 
Published: December 2013

Abstract
The spectral selectivity of Cu–Al2O3 cermet solar absorbers was studied theoretically and experimentally in different layer designs. The results showed clearly that, by increasing the substrate temperature during film deposition, the desired random roughness features will be created on the surface of the cermet, which leads to higher selectivity. Theoretical simulation showed that a single cermet structure with the assistance of an anti-reflection layer, results in the best optical properties. Instead of such a structure, which is sensitive to fine thickness control, it was tried experimentally to increase the selectivity of a single cermet structure as much as possible using a roughness template layer. Surface roughening using such a layer design increased the solar absorptance from 0.840 to 0.956 while keeping the thermal emittance almost unchanged at about 0.028.
Progress in understanding the metallurgy of 18% nickel maraging steels
Authors: Rao Muktinutalapati Nageswara 
Published: December 2013

AbstractMaraging steels based on iron–nickel martensite constitute a very important family of high-strength steels, which distinguishes itself by demonstrating an unparalleled combination of excellent fabricability and high strength and fracture toughness after heat treatment. Heat treatment of these steels has now been perfected to ensure consistently high levels of strength, ductility, and toughness in a variety of product shapes and sizes. Cobalt-free variants have been commercialized as part of efforts to save production costs. Further knowledge has been generated on 18% nickel maraging steels regarding phases precipitating during aging, thermal embrittlement, thermal cycling and austenite reversion/retention and their effect on mechanical properties. The paper reviews the progress made over the last one and half decades.
Experimental study and thermodynamic assessment of the ZrO2–DyO1.5 system
Authors: Wang Chong , Zinkevich Matsvei , Aldinger Fritz 
Published: December 2013

Abstract
The phase equilibria and thermodynamic properties in the ZrO2 – DyO1.5 system have been studied using the experimental methods of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential thermal analysis and high temperature drop calorimetry. The tetragonal + fluorite and fluorite + C-Dy2O3 phase equilibria between 1400 °C and 1700 °C have been determined, together with the enthalpy increments of the materials with 30 mol.% and 50 mol.% DyO1.5 in the temperature range 200 – 1400 °C. Furthermore, the martensitic transformation temperatures (As, Ms) have been measured for the samples with 1 and 2 mol.% DyO1.5. Finally, thermodynamic assessment has been carried out using the experimental results obtained and literature data.
Thermal stability of ECAP processed pure Cu and CuZr
Authors: Molodova X. , Khorashadizadeh A. , Gottstein G. , Winning M. , Hellmig R. J. 
Published: December 2013

Abstract
Samples of pure Cu and Cu with 0.17 wt.% Zr were processed by equal-channel angular pressing up to 12 passes with a 90° die angle using route Bc. Microstructure evolution after deformation and subsequent heat treatment of this severely deformed material was investigated. The deformed and annealed states were characterized by electron back scatter diffraction, transmission electron microscopy, optical microscopy and microhardness tests. The microstructural changes were compared to the behavior of specimens produced by conventional cold rolling. The annealing phenomena were analyzed with regard to recrystallization and grain growth mechanisms. It is shown that the microstructural change during annealing of equal-channel angular pressing deformed specimens has to be associated with discontinuous recrystallization. CuZr samples showed a significantly higher thermal stability against recrystallization than pure Cu samples. This is demonstrated to be primarily due to impurity drag.
Enhancement in mechanical behavior and wear resistance of severe plastically deformed two-phase Zn–Al alloys
Authors: Purcek Gencaga , Karaman Ibrahim , Yapici Guney Guven , Al-Maharbi Majid , Kuçukomeroglu Tevfik , Saray Onur 
Published: December 2013

Abstract
The microstructural evolution, tensile response and wear properties of a two-phase Zn – Al alloy (Zn-8 wt.% Al, ZA-8) have been studied after severe plastic deformation by equal channel angular extrusion (ECAE). The experimental results reveal that the strength levels of the ECAE processed samples were considerably improved regardless of the processing route. More importantly, the elongation at fracture was dramatically increased after ECAE. The optimum tensile properties (high strength and high ductility) were reached after eight ECAE passes following route BA. It was also found that the wear rate of severe plastically deformed ZA-8 is considerably lower than that of the as-cast alloy, especially under high applied pressures, demonstrating improved wear resistance of ZA-8. Moderate strength and high ductility along with improved wear resistance in the ECAE processed ZA-8 samples in comparison with the brittle as-cast alloy makes these alloys attractive for wear-sensitive structural applications.
Microscale characterization of bitumen – back-analysis of viscoelastic properties by means of nanoindentation
Authors: Jäger Andreas , Lackner Roman , Stangl Klaus 
Published: December 2013

Abstract
In order to understand the complex thermo-rheological behavior of asphalt, stemming from the viscoelastic nature of bitumen, the nanoindentation (NI) technique is employed. Hereby, the load history applied onto the indenter tip is characterized by a loading, holding, and unloading phase. As regards the identification of viscoelastic properties, a recently published back-analysis scheme, employing the holding phase of the NI test, is extended towards fractional-creep models. In fact, this type of model is found to perfectly describe the viscoelastic behavior of bitumen. Based on the identified viscoelastic model parameters, the influence of loading rate, maximum load, and temperature on these parameters is investigated. Hereby, the temperature dependence of creep parameters follows an Arrhenius-type law. In addition to the model parameters, application of the so-called grid-indentation technique within NI testing provides insight into the bitumen microstructure and the mechanical behavior of the different bitumen phases. The results obtained indicate the existence of a string-like microstructure embedded into a less viscous matrix material.
Bestimmung der Messunsicherheit bei der Härteprüfung, Einbringung der Bestimmung der Messunsicherheit in das QMH, Verfahrensanweisung des Qualitätsmanagements
Authors: Baudzus Dietmar , Polzin Thomas , Schwenk Dieter 
Published: December 2013

Kurzfassung
Nach der nächsten Revision der Normen für die Härteprüfung [1–3] wird eine Bestimmung der Messunsicherheit [4,5] Teil der Normen sein. Die Autoren wollen die Anwender von Härteprüfmaschinen [6–13] darauf aufmerksam machen, wie die Messunsicherheit in die Teile 1 der Normen [1–3] als informative Anhänge eingebracht werden. Die Veröffentlichung besteht aus drei Abschnitten. In der ersten Veröffentlichung [14] werden insbesondere die beiden vorgeschlagenen Methoden für Teil 1 der ISO Normen für Härteprüfung erklärt. In Abschnitt 2 [15] wird ein EXCEL-File beschrieben für die periodische Prüfung und die Bestimmung der Messunsicherheit. Der folgende Teil drei betrifft die Einbringung der Bestimmung der Messunsicherheit in das QMH.
Gemeinschaftsversuch an einem Sandwichverbund
Authors: Carle Veronika , Täffner Ulrike , Kopp Wolf-Ulrich 
Published: December 2013

Kurzfassung
Der Arbeitskreis Probenpräparation im Fachausschuß Materialographie der DGM führte im Jahr 2003 als Gemeinschaftsversuch die metallographische Anschliffpräparation an einem Sandwich-Werkstoffverbund durch.
In 15 metallographischen Laboratorien wurde das Probenmaterial, bestehend aus Stahl-Aluminiumschaum-Stahl mit den zur Verfügung stehenden Geräten und Verbrauchsmaterialien präpariert, das Gefüge kontrastiert und qualitativ und quantitativ beurteilt.
Die unterschiedlichen Präparationsabläufe werden beschrieben, die dokumentierten Gefüge gezeigt und die unterschiedlichen Kommentare der Teilnehmer zusammengefasst und ausgewertet.
Hinweise zur optimalen Präparation werden gegeben.
Effects of Al Sputtering Power on the Structure and Growth Morphology of (Ti, Al)N/AlN Multilayer Coatings
Authors: Üstel Fatih 
Published: December 2013

Abstract
Multilayer TiAlN and AlN coatings were deposited from two targets onto high speed steel (HSS) and hard metal (HM) substrates by pulsed DC magnetron sputtering. TiAl target power was held constant while aluminum target power was varied. Scanning electron microscopy and X-ray diffraction techniques were used for the structural and morphological characterization. Aluminum target power had an influence on the coating structure and morphology. Coatings produced with low aluminum target power had B1 type cubic structure. As the power was increased, the hexagonal structure becomes clearer.
Correlation Between the Microstructure of Galvannealed Coatings and the Defoliation during Press Forming
Authors: Hong Moon-Hi 
Published: December 2013

Abstract
The defoliation properties of galvannealed coating, so-called powdering and flaking, in continuous galvanizing line were investigated by scanning electron microscopy, X-ray diffraction, roughness profiler and deep drawing test. Both aluminum content in molten zinc and galvannealing temperature were turned out to be critical factors on the microstructure and mechanical properties of galvannealed coatings. Below 0.135 wt% Al, coating surface composed of the mixture of granular d1p and columnar z phases. While, above 0.155 wt% Al, coating surface contained the mixture of granular d1p and pan-cake d1k phases. The appearance of brittle d1k phase approximately 10 μm in size can account for the high amount of defoliation during deep drawing test. The formation of relatively ductile z phase and thin G phase contributes to improve the press formability. The optimazation of the surface microstructure controlling the ratio of granular d1p and columnar z phases was important to reduce the powdering.
Einfluss der Lotzusammensetzung auf die Gefügeentwicklung in Magnesium-Lötverbindungen
Authors: Wielage Bernhard , Mücklich Silke 
Published: December 2013

Kurzfassung
Ein in der jüngsten Vergangenheit stetig gestiegener Einsatz von Magnesiumbauteilen wirft die Frage nach geeigneten Fügetechnologien auf. Es wird ein umweltfreundliches Lötverfahren entwickelt, welches durch Ultraschall auf den Einsatz von Flussmitteln verzichtet und gleichzeitig gut in den Produktionsprozess integrierbar ist. An den Magnesiumgrundwerkstoffen AZ31 und AZ91 werden Lötversuche durchgeführt. Als Lote dienen eutektikumsnahe Legierungen auf der Basis Mg-Zn bzw. Mg-Zn-Al.
In Abhängigkeit von der Zusammensetzung der Lotlegierung werden unterschiedliche Gefügeausbildungen beobachtet: Steigende Aluminiumgehalte zwischen 0 und 10 Gew.-% bewirken eine zunehmende Vergröberung der eutektischen Gefüge im Nahtbereich.
Materialmikroskopie unter besonderer Berücksichtigung der Kunststoffe
Authors: Trempler Jörg 
Published: December 2013

Kurzfassung
Messende lichtmikroskopische Methoden, wie z.B. die Bestimmung der optischen Doppelbrechung haben überall dort eine überragende Bedeutung, wo in den zu untersuchenden Materialien bedingt durch den molekularen Aufbau mit lichtmikroskopischen Methoden kein Gefüge sichtbar gemacht werden kann. Das trifft auf alle amorphen Kunststoffe, wie z. B. Polystyrol zu.
Ein besonderer Vorteil der Bestimmung optischer Daten an Kunststoffen besteht in der engen Korrelation dieser Daten zu den Kunststoffeigenschaften. Dadurch lassen sich relativ einfach online Einrichtungen zur zerstörungsfreien Charakterisierung der Produkte im Fertigungsprozess integrieren.
Aber auch an teilkristallinen Polymeren können messende Verfahren zusätzlich zu der dort oft möglichen Gefügebewertung eingesetzt werden und liefern zusätzlich wertvolle Informationen. Diese Methoden werden im Teil B des Artikels ausführlich dargestellt.
Neben der Bestimmung optischer Daten können zu den messenden Verfahren der Lichtmikroskopie noch eine Reihe weiterer Messmethoden gerechnet werden. Dazu gehören z. B. die Bestimmung der Mikrohärte, die Tief- und Hochtemperaturmikroskopie, Kristallisations-, Auflösungs-, Quell- und Diffusionserscheinungen im Mikroskop in Mikroküvetten sowie DTA – Untersuchungen an geringsten Mengen teilkristalliner Kunststoffe und an Kunststoffgemischen sowie-blends in speziellen Mikroheiztischen. Diese Verfahren werden ebenfalls im Teil B beschrieben.
Silicon Carbide from Sludged Silicon Powder
Authors: Choi Mi-Ryoung , Kim Yeong-Cheol , Chang Young-Chul 
Published: December 2013

Abstract
Sawing silicon ingot with abrasive slurry generates sludge that includes abrasive powders, cutting oil, and silicon powders. The abrasive powders and cutting oil are being separated and reused. Mixing the remained sludged silicon powders with carbon powders and subsequent heattreatment are conducted to produce silicon carbide. Thermodynamic calculation is performed to find an optimum formation condition for the silicon carbide. Silicon carbide whiskers are mainly formed at 1400°C in a closed system, instead of silicon carbide powders. Impurity related mechanism is attributed to the formation of the silicon carbide whiskers, as metal impurities are contained in the sludged silicon powders.
Bildanalytische Formanalyse und Klassifizierung der irregulären Graphitmorphologie in Gusseisen
Authors: Velichko A. , Mücklich F. 
Published: December 2013

Kurzfassung
Die Unterscheidung der verschiedenen Graphitmorphologien in Gusseisen erfolgte bisher im Wesentlichen qualitativ durch subjektiven Vergleich mit Richtreihenbildern. In Hochleistungsanwendungen im Motorenbau werden nunmehr objektive quantitative Messungen der jeweiligen Graphitanteile benötigt, damit die mechanischen Eigenschaften reproduzierbar erreicht werden können.
Vorgestellt werden bildanalytische Untersuchungen zur automatischen Klassifizierung von Lamellen-, Vermikular- und Kugelgraphitformen, sowie Graphitformen in Temperguss. Dabei wurden insbesondere teilchenbasierte Messmethoden angewendet. Unterschiedliche Formparameter wurden in dieser Arbeit zusammengefasst, und ihre Relevanz für die Charakterisierung und Klassifizierung irregulärer, komplexer Graphitteilchen in Gusseisen wurde bestimmt. Es zeigte sich, dass die Kombination der Formparameter Rundheit und Kompaktheit die präziseste Klassifizierung liefert. Ein Klassifizierungsalgorithmus wurde mit Berücksichtigung der Abhängigkeit der Formparameter von der Teilchengröße entwickelt. Die traditionelle subjektive Analyse der Gusseisengefüge anhand EN ISO 945 kann durch die Anwendung der neu vorgeschlagenen Methode mit einer automatischen reproduzierbaren Graphitformcharakterisierung und Klassifizierung deutlich verbessert werden.
Rapidly Solidified Microstructure and Failure Analysis of Powder Metallurgy Al-Si Alloys
Authors: Hong Soon-Jik , Kim Ha-Young , Kim Gyeong-Hwan 
Published: December 2013

Abstract
The microstructure of the extruded bars showed a homogeneous distribution of eutectic Si and primary Si particles embedded in the Al matrix. The grain size of α-Al varied from 150 to 600 nm and the size of the eutectic Si and primary Si in the extruded bars was about 100–200 nm. The room temperature tensile strength of the alloy with a powder size < 26 μm was 322 MPa, while for the coarser powder (45–106 μm) it was 230 MPa. With decreasing powder size from 45–106 μm to < 26 μm, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultra-fine grained constituent phases. The thickness of the deformed layer of the alloy from the coarse powder (10 μm at 3.5 m/s) was larger on the worn surface in comparison to the bars from the fine powders (5 μm at 3.5 m/s) due to the lower strength of the bars with coarse powders. The fracture mechanism of failure in tension testing and wear testing was also studied.
Metallographische Untersuchung eines Toledostahlschwertes
Authors: Salinas Ruiz Ma Dolores , Criado Martin A. Javier , Valverde Virginia Ramos , Peces Raquel Arévalo , Fernández Jorge Chamón , Dietz Christian , Martínez Juan A. , Criado Portal Antonio J. 
Published: December 2013

Kurzfassung
In der vorliegenden Arbeit wurde die metallographische Struktur eines Paradeschwertes untersucht, welches in der Königlichen Fabrik zu Toledo, Spanien, um das Jahr 1851 hergestellt wurde. Das Schwert war Teil der Uniform eines Kavallerieoffiziers. Zur Untersuchung wurden Rasterelektronenmikroskopie (REM) sowie energiedispersive Röntgenstrahlanalyse (EDX) verwendet. Es konnte die hervorragende Verarbeitung des Schwertes, bestehend aus zwei durch Heißschmieden verschweißten Stählen unterschiedlichen Kohlenstoffgehaltes, aufgezeigt werden. Dies erklärt auch die ausgezeichneten mechanischen Eigenschaften des Schwertes, sowie den historisch herausragenden Ruf von Hieb- und Stichwaffen aus der Königlichen Fabrik zu Toledo.
TEM Study of Bainitic Low-Carbon HSLA Steel: The Orientation Relationships of Cementite
Authors: Illescas Silvia , Fernández Javier , Asensio Juan , Guilemany Josep Maria 
Published: December 2013

Abstract
Two different bainitic structures can be present in steel depending on the heat treatment to which the samples are subjected. The two different types of bainitic structures exhibit a different orientation relationship between the cementite and the ferrite matrix. The Pitsch orientation relationship is observed in upper bainite while the Bagaryatski orientation relationship is observed in lower bainite [1]. Different heat treatment samples of low-carbon High Strength Low Alloy (HSLA) steel were studied using TEM observations in order to ascertain the orientation relationship between ferrite and carbide in the different bainitic structures and to determine whether this relationship may indicate the type of bainitic structure.