bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructures of Erbium Modified Aluminum-Copper Alloys
Authors: Berghof-Hasselbächer E. , Masset P.J. , Zhang L. , Liu L. , Jin Z. , Schmidt G. , Galetz M. , Schütze M. 
Published: December 2013

Abstract
Alloying with rare earth metals improves to the mechanical properties and corrosion resistance of aluminium base alloys at high temperatures. The rare earth metal erbium may be used for grain refinement. Within a project of computer-aided alloy development based on the CALPHAD (CALculation of PHAse Diagrams) method various alloys were melted on the Al-rich side of the ternary system Al-Cu-Er under argon atmosphere and their microstructures were characterized in the as-cast state or after long-term isothermal annealing (400°C/960 h) by means of different investigation techniques. As a result, the phases fcc(Al), τ1-Al8Cu4Er, θ-CuAl2, η-CuAl, and Al3Er were identified, their compositions and fractions were quantified, and their hardnesses were determined. The experimental obtained microstructures agree very well with the calculated solidification behaviors of the cast alloys. The knowledge gained from this work about the phase compositions and microstructures can also be utilized for the fine optimization of the phase diagram.
Fracture of a Compressor Stator Blade in a Gas Turbine Engine
Authors: Neidel A. , Matijasevic-Lux B. 
Published: December 2013

Abstract
On the occasion of the revision of a gas turbine power plant in Northern Germany, a surface crack was detected in one of the 44 stage 0 compressor stator blades during a routine non-destructive testing of the blades. By then the engine had completed more than 38,000 h of operation. The damaged blade was precision drop-forged and copy-milled of X20Cr13 and for some time was wearing a subsequently applied corrosion protection coating containing aluminium pigments. The blade's condition before the subsequent coating was applied is unknown.
The metallurgical investigation found that the cause of failure was corrosion fatigue.
„How exactly does this work?”
Authors: Reiter K. , Schnarr H. 
Published: December 2013

Abstract
In the course of the miniaturization and compaction of components and assemblies of components, the application of metallographic target preparation methods has seen a noticeable boost in recent years – not just in electronics industry but also in other industries and in the field of quality assurance in general. In this context, methods are as manifold and diverse as there are possible targets. Besides the classical method, that is progressive hand grinding accompanied by constant visual checks, more and more semi-automatic and automatic systems or aids are used, aiming at rendering the preparation process more user-independent, more effective, and more reproducible.
The replication “target preparation” of the DGM working group aims at illustrating common target preparation methods in the field of materialography and at comparing these methods in terms of preparation effort and accuracy by means of typical samples. Besides reaching the target levels, the focus was also on preparation quality. As samples of electronic components/assemblies usually provide all possibilities of combinations of materials and as such impose higher requirements in terms on the preparation as for homogenous materials, they were chosen as test material.
Evaluating the test results revealed the entire range of applied methods with comparable resulting accuracy, but partially differing qualitative results and different levels of effort. Procedures during these preparations resemble each other and as a result of the test, recommendations could be made for target preparation in general.
Characterization of some Lead-Free Bronzes
Authors: Živković D. , Mitovski A. , Novaković S. , Balanović Lj. , Marković D. , Marjanović B. 
Published: December 2013

Abstract
The results of some lead-free bronzes characterization are presented in this paper. Investigated samples, produced in the Company for production, processing and trade of non-ferrous, rare and noble metals “11. mart” AD Srebrenica (BiH), were examined using optic microscopy, hardness, microhardness and electric conductivity measurements in order to determine their structural, mechanical and electric characteristics.
Effect of Cu Addition on Surface Morphology of Bake Hardenable Galvannealed Steel Sheets
Authors: Hong M.-H. , Kim S.-I. , Yang H.-M. 
Published: December 2013

Abstract
The effect of chemical composition on the surface characteristics of the hot-dip galvannealed (GA) steel sheets with a carbon content as low as 15 ppm strengthened by Cu and/or Mn sulfides instead of Ti and/or Nb carbides has been studied. The most important goal for developing the new type of steel sheets is focused on the achievement of the extreme surface quality to fulfill the high aesthetical requirements for defect-free automotive outer panels. The shape and distribution of the surface enrichments of Cu, Mn, Al and O on the GA steel sheets were characterized by OM, SEM and TEM. Especially, formation mechanism of the narrow streaky mark with the width of 50–100 µ m occasionally observed on the surface of GA steel sheets will be presented.
Y2BaCuO5 Particle Distribution in YBa2Cu3O7-y Grains of Melt Growth Processed YBCO Oxides
Authors: Kim C.-J. , Park S.-D. , Park H.-W. 
Published: December 2013

Abstract
Y2BaCuO5 (Y211) particle distribution within YBa2Cu3O7-y (Y123) grains of YBCO samples melt growth (MG) processed was examined. To understand the processing variables on the Y211 distribution, a cooling rate (R
C=1 K/h to R
C=20 K/h) through a peritectic temperature (T
p = 1010 °C), a precursor powder size and composition were changed. Two different Y211 distributions (a linear x-like track and planar butterfly-like pattern) were observed, depending on the processing variables. The linear x-like Y211 tracks were observed in the Y123 samples prepared using a stoichiometric Y123 precursor, whereas the planar butterfly-like Y211 patterns were observed in the Y1.8Ba2.4Cu3.4O7-d (Y1.8) samples prepared using an Y211-excess composition precursor. The track and planar Y211 patterns were clearer at lower R
C (slower growth rate of Y123 grains) and for the smaller Y211 particles. In contrast, the random Y211 distribution was dominant at the higher R
C and for the larger Y211 particles. The Y211 distribution patterns in the Y123 grains were explained in terms of the interfacial energy difference among growing Y123 fronts.
Lacunarity Term as a Basis of Multiscale Quantification of Structural Components Distribution Inhomogeneity of Multiphase Materials
Authors: Chmiela J. , Słota D. , Szala J. 
Published: December 2013

Abstract
The paper presents the quantification results of the inhomogeneity of phase distribution in intermetallic alloys from the Mg-Al-Sr system after die-casting and gravity casting, the quantification results of phase β of alloy Ti-6-4 after hydrogen treatment and cyclic heat treatment, and of intragranular regions of diverse crystallographic orientation in the copper microstructure in a state of strain and in a recrystallized state. The quantification of the distribution inhomogeneity, based on the concept of directional lacunarity, is effective and precisely detects the size of inhomogeneity and the degree of its intensity, irrespective of the morphology of microstructural components. An analytical description of inhomogeneity allows comparing the results of quantification, regardless of the size of the sets analyzed.
Preparing and Etching Titanium to Document Surface Effects
Authors: Gammon L. M. , Boyer R. R. 
Published: December 2013

Abstract
This paper is a follow-up and update of the article “Titanium and Its Alloys” in Volume 9 of the ASM Handbook, Metallography and Microstructures [1]. Because of its inherent characteristics, titanium is one of the more difficult metals to prepare for metallographic examination, as illustrated below. The challenge is to understand and minimize metallographic preparation artifacts through an understanding of their cause. They will be introduced if the wrong preparation steps and/or etching techniques are applied. For example, if one used the metallographic preparation process for a body centered cubic tempered martensitic steel, etching of Ti and its alloys would not reveal the true structure. This article covers the effect of etchant selection and etching time, the effect of remnant mechanical deformation and cold work produced during specimen preparation, the influence of interstitial contamination and enrichment on the microstructure, and the effect of these problems on heat affected zones.
Metallurgical Failure Investigation of Cracked Hook Nuts Used for Upending Gas Turbine Rotors on Site
Authors: Neidel A. , Fischer B. 
Published: December 2013

Abstract
Two types of non-metallic inclusion stringers were found in so-called upending hook nuts, in the vicinity of an indication on the bore wall's surface, first, manganese sulfides that can be expected in this material, and second, endogeneous oxidic inclusions from the steelmaking process. The latter ones, too, can be expected to an extend in the structural steel that was used to make the hook nuts from. However, they are present in an excessive amount and were causative for the decohesions that produced the reported MT indications. The forging process which was employed to produce the semifinished product used to machine the hook nuts from was unable to fragment and disperse the non-metallic inclusions sufficiently as is usually the case.
Metallurgical Failure Investigation of Overheated and Fractured Investment Cast Nickel-base Bolts Made of Inconel 939
Authors: Leggemann S. , Cagliyan E. , Riesenbeck S. , Neidel A. 
Published: December 2013

Abstract
A number of small investment cast nickel-base bolts used for fastening metallic heat shields in combustion chambers of large industrial gas turbine engines were found fractured upon a regular hot gas path inspection in one particular engine. No similar findings were reported from any other engine in the field. The fracture of a single-digit number of these fasteners in an individual engine did not cause the liberation of the respective heat shields, hence no secondary damage occurred. The subject bolts were fractured in the head region that is also used to apply the fastening torque upon assembly of the heat shields. No evidence of fatigue, creep or hot corrosion damage was found. From the results of the metallurgical failure investigation described in this paper it was concluded that the subject bolts failed by torsional and/or tensional overload. Severe embrittlement by precipitation of secondary phases due to long-term high temperature service exposure contributed to the failure. The bolts ran hotter than intended by design. It is likely that cracks were induced in the bolt heads by over-torquing them upon assembly. Those cracks later grew in service.
Metallographic Preparation of Aluminium-Titanium Composites
Authors: Romberg J. , Freudenberger J. , Scharnweber J. , Gaitzsch U. , Marr T. , Eschke A. , Kühn U. , Oertel C.-G. , Okulov I. , Petters R. , Skrotzki W. , Eckert J. , Schultz L. 
Published: December 2013

Abstract
There is no method that allows the simultaneous preparation of titanium and aluminum, so that both phases can be investigated by means of scanning electron microscopy (SEM) at the same time. Especially local orientation measurements by electron back scatter diffraction (EBSD) are challenging as they require a very good surface quality. This study deals with the preparation of aluminum/titanium composites, produced by Accumulative Roll Bonding (ARB) as well as with their microstructural analysis emphasing on the metallographic sample preparation. Well established routes of metallographic preparation for aluminum and titanium are facing serious problems such as rounding of edges, arising of deformation layers, blurred layers and oxide layers. This is of particular concern when these routes are applied to Al/Ti multilayered samples without adaption. This study reveals a route for metallographic sample preparation that enables SEM including EBSD analyses of Al/Ti composites for both phases simultaneously.
Numerical Investigation of Hot Embossing Filling Characteristics
Authors: Kang T. G. , Kwon T. H. 
Published: December 2013

Abstract
In the present study, we aim to investigate the basic flow and filling characteristics in the hot embossing filling stage, which depend on the geometry and processing conditions. For this purpose, we have developed a numerical analysis to simulate hot embossing filling using the finite element method and verified the developed program using the existing experimental data. As s basic study to understand hot embossing filling we have chosen a simple rectangular cavity with repeating protruded parts as a computational domain. The filling pattern was found to be significantly influenced by the variation of thickness of polymer substrate for the same stamp geometry, thermal boundary condition, and the embossing time. Filling from the border of the cavity is clearly observed as the thickness of polymer substrate decreases under the equal wall temperature condition. As for the effect of unequal temperature at the stamp and solid base plate, we found that the filling pattern has been affected by the temperature difference between the two surfaces and embossing time. The localized uprising flow results from the thermal boundary condition and subsequent change in the effective thickness of polymer substrate having enough fluidity to deform.
Effect of Aerodynamics on Film Blowing Process
Authors: Zhang Z. , Lafleur P. G. , Bertrand F. 
Published: December 2013

AbstractA Computational Fluid Dynamics (CFD) technique using a renormalization group (RNG) k –ε model and Fluent software was employed to analyze numerically the effects of aerodynamics on the air ring cooling system of a film blowing process. An in-line scanning camera system developed in our lab was used to study experimentally the detailed dynamics of bubble instabilities. An operation window for the heat transfer coefficient and the maximum air velocity function was established. The simulation results showed that it is adequate mainly at low BUR (Blow-Up-Ratio) outside of the air ring. The relationship between thermal inertia and cooling air aerodynamics for different bubble geometries was also explored. Different bubble shapes, for the same BUR, produced significant differences in the airflow pattern and heat transfer coefficient. The combination of experimental measurements and numerical simulations indicated that various cooling rates result in important variations in the dynamics of bubble instabilities for different BUR bubbles. It was observed that increasing the cooling rate can destabilize the lower BUR bubbles, but stabilize the higher ones due to the production of different bubble shapes. Finally, it is shown that the bubble instabilities depend on the static pressure distribution along the bubble surface, and that minimizing the pressure gradient can stabilize the bubbles.
A Study of Integration of LIGA and M-EDM Technology on the Micro Injection Molding of Super Thin Plates with Micro Through Holes
Authors: Tseng S.-C. , Chen Y.-C. , Lin C.-H. , Shew B.-Y. , Kuo C.-L. 
Published: December 2013

Abstract
There are still some difficulties in injection molding a super thin plate with micro through holes. Nozzle or filter plates are some examples of typical products. Conventional processes to manufacture nozzle plates of ink jet printer heads are electroplating or laser machining. In order to reduce the production cost and improve the performance of nozzle plates, a new approach, micro injection molding, is introduced to manufacture nozzle plates in this study. The micro mold was made by integration of the LIGA and M-EDM technology to improve the positioning and alignment accuracy. After assembling the micro mold, micro injection molding technique was applied to produce four nozzle plates in one shot. There are sixty micro through-holes on each plate and their diameters have been inspected and met the specification, 101 ± 1 microns, under a proposed vario-thermal molding process. The flow hesitation problem for molding a thin film of 50 microns was then solved. Experimental and simulation results indicated that the most significant factor for molding these nozzle plates is the initial mold temperature. This work recommends that the best initial mold temperature for molding such a thin film with the nozzle array is about 150°C for PP. The manufacturing procedures proposed here are believed to be more accurate and economical, and can be applied to mold similar micro parts.
Carbon Black Filled Polyester as Electrically Conductive Master Batch for Fibers
Authors: Jin X. , Xiao C. F. , An S. L. , Jia G. X. , Wang Y. Y. 
Published: December 2013

Abstract
Carbon black (CB) was added into a matrix of poly(ethylene terephthalate) (PET) by melt processing to prepare electrically conductive master batch (ECMB) for fiber applications. The amount of CB required to achieve a desired electrical property often results in poor mechanical properties of the final fibers. To solve this problem, a type of ECMB with a lower percolation threshold was designed by incorporating titanate coupling agent treated CB and using a matrix blend (adding polyethylene (PE) into PET). The effects of titanate coupling agent treatment and the matrix blend on the percolation threshold of ECMB are discussed and the effect of lower percolation threshold on the mechanical properties of final melt-spun fibers was investigated. The results indicated that titanate coupling agent treatment and a matrix blend are able to reduce the percolation threshold and thereby minimize problems with the mechanical properties of the final fibers, yet maintain the desirable electrical property.
Effect of the Chemical and Morphological Conditions of the Die Wall on the Extrusion of Linear Polyolefins
Authors: Larrazabal H. J. , Hrymak A. N. , Vlachopoulos J. 
Published: December 2013

Abstract
This study examines the effects of average surface roughness and composition of the die wall surface on the critical shear stress for the onset of instabilities in die extrusion. Increasing the average surface roughness of the die wall from 0.1 to 15m produced an increase of the critical shear stress for the onset of flow instabilities by as much as 20% during the extrusion of HDPE. The surface of the extrudates obtained with dies having an average surface roughness greater than 5lm showed lines and grooves along the direction of extrusion. Chrome-plated and nickel-plated dies showed an average 28% increase in the critical shear stress as compared to conventional steel dies. The chemical composition of uncoated steel dies wall surfaces, including the presence of iron oxide, did not affect the critical shear stress for the onset of sharkskin significantly regardless of the type of resin used.
Polymer Processing Extrusion Instabilities and Methods for their Elimination or Minimisation
Authors: Agassant J.-F. , Arda D. R. , Combeaud C. , Merten A. , Münstedt H. , Mackley M. R. , Robert L. , Vergnes B. 
Published: December 2013

Abstract
This paper presents and reviews findings in relation to three key areas where polymer processing instabilities occur. The paper also describes methods that can be utilised to reduce, or eliminate, the particular instability. Using previously published results in each of the three areas and work presented in the paper, physical insight into the three mechanisms is reviewed and compared. Extrusion instabilities develop with increasing extrusion rate and the onset of extrusion instability is often a key limitation to the maximum output of an extrusion line. The sharkskin instability is an exit effect instability that can be modified by changing exit geometries and eliminated using certain additives. The stick-spurt instability is intimately related to wall boundary conditions which can be influenced by certain wall and polymer formulations. Finally volume instabilities occur in the entry region of a die and result in a highly distorted product. The instabilities are related to viscoelastic effects within the die and can be minimised by appropriate die and polymer modification. The paper provides sufficient experimental background to identify the key physical aspects associated with each of the instabilities and this in turn provides insight into the different way each instability occurs and how they can be minimised.
PLLA Morphology Controlled by Dry-cast Process
Authors: Meng B. , Cui F. Z. , Cai Q. , Zhang Y. 
Published: December 2013

Abstract
The influence of solvent evaporation rate, in the dry-casting process, on crystallinity and morphology of crystallizable polymeric membrane was studied. Poly-l-lactic acid (PLLA) was taken as an example. The membranes were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). By controlling the solvent evaporation rate, samples with various crystallinities were prepared. From higher to lower crystallinity the membranes exhibit three types of surface morphology in sequence: granule, stripe and smooth.
Description of the Pressure/Throughput Behavior of a Single-screw Plasticating Unit in Consideration of Wall Slippage Effects for Non-Newtonian Material and 1-D flow
Authors: Potente H. , Timmermann K. , Kurte-Jardin M. 
Published: December 2013

Abstract
Up to now, existing mathematical models can only describe the throughput behaviour of compounding extruders assuming the condition of a wall adhering melt. However, there is a variety of polymer melts, as well as polymer suspensions, ceramic materials and food stuffs, which in the course of manufacturing are wall-slipping. A mathematical model describing the behaviour of the isothermal flow of non-Newtonian materials is developed. In addition to the development of the analytical model, which is based on Flumerfelt et al. [1] and Hirshberger [2], the flow behaviour of wall-slipping polymer melts is also analysed using Finite-Element-Simulations (FE). Comparison of the results for pressure, throughput and velocity profiles along the channel depth shows a very high degree of agreement.
The Reactive Extrusion of Thermoplastic Polyurethane and the Effect of the Depolymerization Reaction
Authors: Verhoeven V. W. A. , Padsalgikar A. D. , Ganzeveld K. J. , Janssen L. P. B. M. 
Published: December 2013

Abstract
The reactive extrusion of thermoplastic polyurethane in a corotating twin-screw extruder was investigated. The polyurethane system consisted of a mixture of 2,4-diphenylmethane diisocyanate (2,4-MDI) and 4,4-MDI, methyl-propane-diol and a polyester polyol. An engineering extrusion model was designed and compared with experimental results. In this validation study the catalyst level, throughput, rotation speed and the barrel wall temperature was varied. A comparison of the experiments with the model showed that the model captured the polyurethane extrusion fairly well. Furthermore, the effect of the depolymerization reaction on the polyurethanes extrusion was investigated. It was found that the extruder operation is gravely affected by the depolymerization reaction: the depolymerization reaction limits the maximal obtainable conversion, stabilizes the extruder operation, and causes undesired post-extrusion curing of the polyurethane.