bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Transition and Thermochromism of the Hybrid (C12H25NH3)2FeCl4
Authors: Guo L.L. , Dai Y.D. , Liu H.X. , Ouyang Shi Xi
Published: March 2009

This paper focuses on the structural change and the thermochromism of the phase transition of the hybrid (C12H25NH3)2FeCl4. The temperature and the structures of the phase transition is investigated by a thermal gravimetry (TG) and differential scanning calorimetry (DSC), an infrared spectra (IR) and X-ray diffraction (XRD) patterns. The UV adsorption spectra account for the thermochromism. The results suggest that the reversible phase transition arises from the structural changes of the organic chains. The thermochromism is presumably due to the electrons redistribution on the levels and to the energy transition to translational and rotational motions of the organic chains.
Effect of Hybrid Length Scales (Micro + Nano) of SiC Reinforcement on the Properties of Magnesium
Authors: Wong W.L.Eugene , Gupta Manoj
Published: March 2009

In this study, pure magnesium reinforced with micron, nano and micron + nano-size SiC particulates was synthesized using powder metallurgy technique coupled with a novel microwave assisted rapid sintering. The sintered billets were subsequently extruded and characterization studies were performed on the extruded specimens to assess the microstructural, physical and mechanical properties of the composites. Microstructural characterization revealed good interfacial integrity between the matrix and reinforcements. Results of thermal mechanical analysis indicate most significant decrease in the coefficient of thermal expansion of the magnesium matrix with the use of hybrid reinforcements. Mechanical characterization revealed that composite samples exhibited an increase in microhardness of the matrix and strength over that of pure magnesium while ductility was adversely affected. An attempt is made to correlate the effect of single length scale and mixed length scales of SiC reinforcement on the properties exhibited by pure magnesium.
Structural Aspects of Phase Transitions
Authors: Kubicki Maciej
Published: March 2009

There are two kinds of structural transformations in the crystalline solid state: solid state reactions, in which the product chemically different from the starting material can be isolated, and polymorphic transitions, when the phases have different organization of identical molecules in the crystal structures. As a consequence, the starting and the final phases of a solid state reaction differ in the melt and vapor, while different polymorphic modifications are identical in melt or gas phase. Some examples of the different phase transitions in the solid state are described in detail: the π-molecular complexes, the hydrogen-bond transformations and the reversible single crystal - twin transition.
Thermal-Driven Evolution of Magnetic Domain Structures in Ultrathin Films
Authors: Zablotskii V. , Maziewski Andrzej , Polyakova T.
Published: March 2009

The thermal-driven evolution of stripe domain structures in ultrathin magnetic films is analyzed with regard to temperature dependencies of the film magnetic parameters. In the vicinity of the Curie temperature or points of the spin reorientation the equilibrium stripe domain period was found to exponentially decrease with increasing temperature. It is shown that the temperature dependence of the characteristic length is the key parameter controlling the domain period changes. Irreversible and reversible changes of the domain period as well as the so-called inverse domain melting are discussed.
A Methodology for Automatically Deriving Simple Electromechanical Equivalent Models from FEM-Models
Authors: Król Rafal , Brökelmann Michael , Wallaschek Jörg
Published: March 2009

FEM is a very important tool for getting the numerical solution of many engineering
problems. It has been widely used in solving structural, mechanical, heat transfer, and fluid
dynamics’ problems as well as problems of other disciplines such as piezoelectricity. Since the
complexity of many problems leads to the formation of models of large dimension, which are
described with many degrees of freedom, their numeric solution makes for the highest demands.
The number of degrees of freedom is often unnecessarily large to represent the structural response
in a limited bandwidth and therefore, in such a case, a reduction should be conducted. The
systematic reduction of complex FE models on simple electromechanical equivalent circuit models
(with less mechanical degrees of freedom) is the subject of this paper. The aim of the work is to
make the reduction in such a way that the characteristics of the systems input/output descriptions
are approximated within a pre-selectable frequency range with sufficient accuracy. A transducerwedge-
system is used as an example for the method, to extract a state space model of the systems
piezoelectric input/output description and to derive the parameters of the electromechanical
equivalent circuit directly from the modal finite element analysis. In the present paper we describe
the general methodology as well as its application to piezoelectric transducers as used in ultrasonic
engineering.
Laboratory Stand for Air Flow Stabilization
Authors: Lipnickas Arūnas , Jankauskaitė Ramunė , Žukauskas Vilmantas , Kubilius Vaclovas
Published: March 2009

In this paper the methodology of composing mathematical models and fault detection &
identification system for a laboratory stand named air flow stabilization system is given. The main
objective of the system identification is to obtain the best mathematical description of a real system
of interest; in our case we have modeled the dynamics of air flow in the tube. In the second part of
the paper the authors present the fault detection system that is designed to detect any abnormality of
air flow in the air tube and to identify four types of occurred faults.
Estimation of Parameters of Impulse Responses of Mechanical Systems by Modified Prony Method
Authors: Slivinskas Vytautas , Šimonytė Virginija
Published: March 2009

In this paper the problem of estimation of parameters of a mechanical system using
sampled impulse response data is considered. For the estimation of the unknown parameters the
modified Prony method is used. It is shown that for the particular data the use of multiple poles
improves the accuracy of the model. The initial Prony method estimates are further optimized by an
iterative Levenberg optimization procedure. The root mean square error (RMSE) is the criteria for
the estimation procedure. The additional modes are used in order to get better results.
The Use of Shape Memory Alloy Wires in Actuators
Authors: Schiedeck Florian , Hemsel Tobias , Wallaschek Jörg
Published: March 2009

Our contribution will describe the basic fundamentals of shape memory alloys. Emphasis will be given to specific characteristics for the use of shape memory wires in actuators. The investigation of shape memory wires in actuators includes qualitative and quantitative benchmarking based on measurements at different test beds. To display applicability of shape memory wires for different tasks, the main focus will be on the influence of different bias forces, the determination of performance, and the possibility of position control without position sensors.
The Stator of Rotating Type Piezo-Motor Based on "Shaking Beam" Actuator
Authors: Vasiljev Piotr , Borodinas S. , Vasiljeva L. , Bareikis R. , Irzhikevichius A.
Published: March 2009

According to previous research on the creation of linear piezo-motors using the “shaking
beam” principle the authors have proposed a new rotating type piezo-motor based on the same
principle.
The advantage of the current motor compared with analogues motors is shown. The proposed motor
uses both actuator of longitudinal-torsion vibration and a wave motor.
In this paper computer simulation by FEM analysis of the proposed system is given. The simulation
results of modeling are confirmed experimentally. The authors used precision laser equipment for
testing and measuring.
Asymmetric PI Controller for Mechatronic Systems
Authors: Baskys A. , Zlosnikas V.
Published: March 2009

An asymmetric PI (aPI) controller based on a control algorithm, which is the
modification of the PI control method, has been suggested. The principal characteristic feature of
the aPI controller is that different values of proportional and integral constants are used at positive
and at negative errors. Contrary to the classical PI controller, the proposed controller allows us to
improve the positive disturbance rejection of control systems without sacrificing the unit step
response dynamics. Results of the investigation of the concrete control systems based on the aPI
controller are also presented. Using the dynamic system simulation program Simulink performed
the investigation.
Robotic Assembly Using Vibrations
Authors: Bakšys Bronius , Puodziuniene Nomeda
Published: March 2009

On the basis of the dynamic model of vibratory alignment the main features of the
vibrational assembly process are investigated. The regularities of non−impact alignment, when an
immovable part is excited in two perpendicular directions, are defined. It is revealed that during the
vibrational alignment the movable part can move from static till dynamic equilibrium position. The
distance between these two positions defines allowable error of mutual positioning of the parts
subject to the assembly, when the unhindered parts insertion is still possible.
On the basis of the dynamic model of vibratory displacement the regularities of a body
displacement under controlled dry friction force at a particular time interval is examined. If elastic
vibrations are excited, dry friction coefficient decreases and smaller friction force acts against the
body displacement. Stoppage of these vibrations causes a steep increase of friction coefficient.
When the body moves from static to dynamic equilibrium position on the inclined plane the
vibratory displacement is governed by the transient regimes of motion.
Assembly robots equipped with passive compliance vibratory end-effectors allow one to
compensate considerably bigger deviations in part’s interposition without using sensors and
feedback systems. Therefore usage of vibratory devices with passive compliance allows one to
significantly reduce the expenses of robotic assembly.
Robotic Simulation and Web-Technology Enabling Collaboration in Digital Manufacturing
Authors: Pieskä Sakari , Sallinen Mikko , Honkanen Vesa-Matti , Kaarela Jari
Published: March 2009

In this paper, robotic simulation and web-technology are considered as collaborative
tools, which enable enterprises to take steps towards digital manufacturing and product lifecycle
management. Some results from developing the work of robot simulation and web-technology in
research laboratories and industrial environments are presented. The application areas include
robotic welding cells, robotic bending cells and robotic material handling cells. Experiences from
the development work with different robot work cells confirm that digital manufacturing technology
will become a practice in manufacturing networks in the future.
Lubrication of Mechatronical Metal Cutting Systems by Means of Technological Liquids
Authors: Vekteris Vladas
Published: March 2009

Lubrication and cooling of a high speed grinding process in the grinding machine as in a mechatronic system using technological liquids are analyzed in this paper. It is shown that in the case of high grinding speed, technological liquids undergo an aeration process and due to this their physical properties change. Reynolds equation, which estimates the aeration liquid, is derived. It is shown, that the application of such an equation is proper only in the finishing of grinding. Experimental research is also presented in the paper, which shows the influence of technological liquids to the temperature field of the grinding machine and to its automatic control.
Calculation of Deformation of a Mobile Elastic Element of the Hydrodynamic Tilting-Pad Journal Bearing
Authors: Vekteris Vladas
Published: March 2009

The hydrodynamic tilting-pad journal bearing with a mobile elastic element and choose of its geometry by calculating deformations are analyzed in the paper. It is shown here, that such bearings with elastic elements can use the kinetic energy of the oil, which appears in the incensement volume. When rotor oscillations appear elastic elements disturb the equilibrium of segments and diminish the influence of oscillation. Differential equations are derived for this aim and they allow choosing geometrical parameters of elastic elements independence on the load intensity and the oil temperature.
Research on a Novel High-Precision Intelligent Displacement Sensor
Authors: Liu Xiao Kang , Peng Dong Lin , Zhang Xing Hong , Cheng Xi Hou
Published: March 2009

A theory of time-space coordinate transformation is presented for measuring space with time. A novel type of displacement sensor named time grating is developed, and methods of electronic rectifying, self-compensation and self-correction are proposed to intelligentize the sensor. Experiment results coming from applications conform to the validity of the proposed theory and methods. The experiment and test results show that high-precision measurement is achieved without high-precision manufacture and that angular displacement is measured very accurately without a dividing scale, which embeds the remarkable characteristics of low cost but high accuracy to the time grating sensor.
Mechanical Properties of Winding Conductors Affected by Cyclic Thermal Overloads
Authors: Višniakov N. , Novickij J. , Ščekaturovienė D. , Šukšta M.
Published: March 2009

The influence of thermal cyclic overloads on mechanical properties of winding
conductors was investigated. Copper-niobium microcomposite, soft and hard pure copper wires
were conditioned at temperatures range from 77 K to 500 K. The treatment was done during 100
cycles of fast conductor cooling to liquid nitrogen temperature and further fast heating in a climatic
chamber. The ultimate tensile stress limit and the elongation at failure of metal-matrix
copper-niobium microcomposite, soft and hard copper wires were measured before and after
thermal treatment with a testing machine at room temperature.
Experimental Industrial Carbon Nanomaterial Production
Authors: Mischenko Sergey V. , Tkachev Aleksey G. , Kalinin Vyacheslav F. , Negrov Vladimir L.
Published: March 2009

At the present stage of development of carbon nanomaterial production technologies
great attention is paid to the creation of equipment that allows for obtaining these materials in
significant amounts.
Tambov State Technical University (TSTU) in cooperation with research and industrial teams
carries out research, as well as design and manufacturing work for process equipment to obtain
carbon nanofibres and nanotubes.
As a result of this work the experimental industrial production technologies for hydrocarbon
catalytic pyrolysis were developed.
Experimental samples of products (nanofibres) were obtained.
Mechatronics Course Design for Industry
Authors: Gürbüz Riza
Published: March 2009

As the field and application of mechatronics grows, Engineering and Vocational and
Technical education must grow with it to meet the needs of industry. This paper focuses on the
designing of a mechatronics courses for industry. University-government-industry and Private
Companies have collaborated in a project and shared responsibilities and tasks.
In this article, we describe our experience in running mechatronics courses for Engineers, Higher
Technician and Technician Courses in Ankara’s industry since 2001.We also describe an industryuniversity
co-operation model, training of trainers, the designing of a mechatronics laboratory and
course in accordance to the expectations of industry, setting up the feedback mechanism of keeping
quality of courses, developing projects financing and management methods
Variable Structure Filter Algorithmic Synthesis
Authors: Dambrauskas Algirdas , Rinkevičius Vytautas
Published: March 2009

The aim of the work is to create and refine methods of algorithmic filter synthesis allowing for the designing of variable structure filters in cases when statistical characteristics of effective signal and interference – non-stationary stochastic processes – are unknown and the application of classic synthesis methods, e.g. Kalman-Busy method, is impossible. The paper presents the basics of an algorithmic variable structure filter synthesis, the essence of which is the formulation of the filter synthesis task in the form of searching optimization and its solution with application of simplex search methods. An example of algorithmic variable structure filter synthesis is presented. Parameters of a variable structure filter transfer function found by algorithmic method correspond to theoretical parameters calculated on the basis of statistical characteristics of input signals.
Phase Transformations in Pearlitic Steels Induced by Severe Plastic Deformation
Authors: Ivanisenko Julia , MacLaren Ian , Sauvage Xavier , Valiev Ruslan , Fecht Hans Jorg
Published: March 2009

The paper presents an overview of a number of unusual phase transformations which take place in pearlitic steels in conditions of the severe deformation, i.e. combination of high pressure and strong shear strain. Strain-induced cementite dissolution is a well-documented phenomenon, which occurs during cold plastic deformation of pearlitic steels. Recently new results which can shed additional light on the mechanisms of this process were obtained thanks to 3DAP and HRTEM investigations of pearlitic steel deformed by high pressure torsion (HPT). It was shown that the process of cementite decomposition starts by carbon depletion from the carbides, which indicates that the deviation of cementite’s chemical composition from the stoichiometric is the main reason for thermodynamic destabilisation of cementite during plastic deformation. Important results were obtained regarding the distribution of released carbon atoms in ferrite. It was experimentally confirmed that carbon segregates to the dislocations and grain boundaries of nanocrystalline ferrite. Another unusual phase transformation taking place in nanocrystalline pearlitic steel during room temperature HPT is a stress induced α→γ transformation, which never occurs during conventional deformation of coarse grained iron and carbon steels. It was concluded that this occurred due to a reverse martensitic transformation. The atomistic mechanism and the thermodynamics of the transformation, as well as issues related to the stability of the reverted austenite will be discussed.
Combined SPD Techniques to Fabricate Nanostructured Ti Rods for Medical Applications
Authors: Salimgareeva G.H. , Semenova Irina P. , Latysh V.V. , Kandarov I.V. , Valiev Ruslan
Published: March 2009

The paper investigates an innovative technological processing method for fabricating nanostructured materials for structural applications. Severe plastic deformation (SPD) and subsequent thermomechanical treatment, was used to produce high physical and mechanical properties in bulk billets.
Nanocrystalline Cu-Al2O3 Composites Sintered by the Pulse Plasma Technique
Authors: Michalski Andrzej , Jaroszewicz Jakub , Rosiński Marcin , Siemiaszko D. , Kurzydlowski Krzysztof Jan
Published: March 2009

The paper presents the results of examination of the structure and properties of
nanocrystalline Cu-Al2O3 composites with the two different Al2O3 contents: 10 and 20 vol.%. The
composites were produced using a mixture of copper and Al2O3 powders with an average crystallite
size of about 60nm for Cu and about 40nm for Al2O3. The powders were consolidated by pulse
plasma sintering (PPS) for 5 minutes at a temperature of 650oC under a load of 60 MPa.
Irrespective of the volumetric content of Al2O3, the relative density of the composites was about
92%, and the average Cu crystallite size was about 80nm. The hardness of the composites varied
with the volumetric content of Al2O3, and was equal to 270 HV0.1 for 20 and to 240 HV0.1 for
10% of Al2O3. The Cu-20%Al2O3 composite had a resistivity of 0.386 while that with 10% of
Al2O3 was 0.149 56m.
X-Ray Analysis of High Pressure Torsion Induced Nanostructures in Ti and Ni
Authors: Kilmametov A.R. , Valiev Ruslan , Alexandrov Igor V.
Published: March 2009

X-ray investigations revealed that the increase in the applied pressure during high
pressure torsion (HPT) of commercially pure Ti leads not only to substructure refinement with an
increase of the dislocation density and microstrain level but also to an α→ ω phase transition at
room temperature. The coexistence of both α and ω phases, the latter known as a high pressure
phase, in the ratio approximately of 1:3 has been obtained after removal of thehigh pressure.
Texture analysis of electodeposited Ni after HPT discovered a new form of crystallite orientation
distribution in the nanocrystalline state. A nearly random orientation crystallite distribution has
been observed unlike the “traditional” case of a shear texture forming in cubic symmetry metals.
The crystallographic texture data obtained were considered as experimental evidence of the changed
plastic deformation mechanisms in nanocrystalline Ni produced by HPT.
Texture Development in a Model Al-Li Alloy Subjected to Severe Plastic Deformation
Authors: Adamczyk-Cieślak Bogusława , Mizera Jaroslaw , Kurzydlowski Krzysztof Jan
Published: March 2009

The texture of Al – 0.7 wt. % Li alloy processed by two different methods of severe
plastic deformation (SPD) has been investigated by X-ray diffraction, and analyzed in terms of the
orientation distribution function (ODF). It was found that severe plastic deformation by both Equal
Channel Angular extrusion (ECAE) and Hydrostatic Extrusion (HE) resulted in an ultrafine grained
structure in an Al – 0.7 wt. % Li alloy. The microstructure, grain shape and size, of materials
produced by SPD strongly depend on the technological parameters and methods applied. The
texture of the investigated alloy differed because of the different modes of deformation. In the
initial state the alloy exhibited a very strong texture consisting of {111} fibre component. A similar
fibrous texture characteristic was also found after HE whereas after the ECAE the initial texture
was completely changed.
Processing by Hydrostatic Extrusion of Titanium Coated with Aluminides
Authors: Garbacz Halina , Pachla Wacław , Wierzchoń Tadeusz , Kurzydlowski Krzysztof Jan
Published: March 2009

The material examined was commercially pure titanium with intermetallic Ti-Al layers
produced by magnetron sputtering followed by glow discharge assisted treatment. This material
was subjected to hydrostatic extrusion at room temperature. This resulted in substantial grain size
refinement in the titanium accompanied by significant property improvement. The intermetallic Ti-
Al layers reduced the pressure required during hydroextrusion and also increased the microhardness
and frictional wear resistance of the material.
High Strength and Ductility of Nanostructured Al Alloy 2024 Subjected to High Pressure Torsion
Authors: Vorona D. , Sharafutdinov Alfred V. , Krasilnikov Nikolay A.
Published: March 2009

The structure and mechanical properties of Al-based alloy 2024 after high-pressure
torsion (HPT) was investigated. Alloy 2024 with homogeneous structure and grain size about 70
nm was obtained using HPT at 6 GPa pressure and 5 turns of the anvils at room temperature. The
nanostructured alloy possessed very high UTS (Ultimate tensile stress) above 1100 MPa at room
temperature, and superplastic behaviour at temperatures over 300°С. The microhardness of the
nanostructured alloy after superplastic deformation (1.5 GPa) was greater than that after the
standard treatment of the coarse-grained alloy (1.2 GPa). The influence of HPT parameters and heat
treatment on the structure and deformation behaviour of the alloy was studied.
The opportunity of achieving a combination high strength and good ductility in metals and alloys
opens perspectives for industrial applications, particularly, in micro-systems and for high-strength
items with complex geometry which could be obtained by superplastic forming.
Isothermal Stress Relaxation of Bulk and Ribbon Pd40Cu30Ni10P20 Metallic Glass
Authors: Bobrov O.P. , Laptev S.N. , Khonik V.A.
Published: March 2009

The paper presents the results of detailed measurements of the isothermal tensile stress relaxation in Pd40Cu30Ni10P20 bulk and ribbon samples, which differ by ∼ 104 times in their production quenching rates. The relaxation law is derived. It is shown that the relaxation kinetics is not much affected by the quenching rate.
Hydrogen Relaxation Process in HiPco Carbon Nanotubes Studied by Mechanical Spectroscopy
Authors: Cantelli Rosario , Paolone Achille , Roth S. , Dettlaff U.
Published: March 2009

The first mechanical spectroscopy experiments in HiPco carbon nanotubes from room temperature to 3 K revealed a thermally activated relaxation process at about 25 K for frequencies in the kHz range. The peak is due to the presence of a very mobile species performing about 103 jumps per second at the peak temperature. The activation energy obtained by the peak shift with frequency is Ea = 54.7 meV; the value of the pre-exponential factor of the Arrhenius law for the relaxation time, τ0 = 10-14 s, which is typical of point defect relaxation and suggests that the process is originated by the dynamics of hydrogen or by H complexes. The peak is much broader than a single Debye relaxation process, indicating the presence of intense elastic interactions in the highly disordered bundle structure. There are indications that the relaxation process is governed by a quantum mechanism.
Giant Piezoelectric and Dielectric Relaxations in Statistical Mixtures
Authors: Chernobabov A.I. , Turik A.V. , Radchenko G.S. , Turik S.A.
Published: March 2009

The effective complex piezoelectric and dielectric constants of disordered heterogeneous systems of the type of statistical mixtures with the components in the form of spheroid-shaped particles equally oriented but randomly arranged in space were studied. It has been found for the first time that in such systems there appears a giant piezoelectric enhancement accompanied by a giant relaxation of piezoelectric coefficients and the dielectric permittivity. Piezoelectric and dielectric spectra differ significantly from the Debye ones and are of Davidson-Cole type. The influence of the aspect ratio of spheroids on the effects under consideration was studied. The physical mechanisms responsible for the anomalies in the behavior of piezoelectric coefficients and the dielectric permittivity were considered.
Dispersion of Dielectric Permittivity in Thin Ferroelectric Lead Titanate Films
Authors: Sidorkin S. , Nesterenko L.P. , Bocharova I.A. , Smirnov G.L. , Sidorkin V.A. , Ryabtsev S.V. , Smirnov A.L.
Published: March 2009

Lead titanate thin films were obtained by plasma-enhanced magnetron sputtering.
Synthesized films demonstrate high temperature stability, relatively narrow maximum at
temperature of phase transition for ε (T ) dependence, great dielectric constant value near the Curie
point, saturated hysteresis loops, and relaxation character for dispersion of dielectric permittivity
similar to bulk samples.
Light-Induced Structural Relaxation and the Photoplastic Effect in Chalcogenide Glasses
Authors: Trunov M.L. , Dub Sergey N. , Shmegera R.S.
Published: March 2009

The combination of depth-sensing indentation and band-gap illumination has been used
to study the photoplastic effect (the reversible influence of light on the flow stress, hardness, and
plasticity) in chalcogenide glasses on a nanoscale. The prominent photoplasticity of thin As-Se
films has been revealed through deviations in the shape of load-displacement curves during
nanoindentation under light illumination from those ones which have been observed for the
material in the darkness. The photoinduced changes in static mechanical properties such as
nanohardness and elastic (Young’s) modulus have been determined. The highest photoplasticity
changes are achieved for As20Se80 films while their photodarkening is the lowest.
Mechanical Spectroscopy of Quasicrystals
Authors: Sinning H.R.
Published: March 2009

The use of mechanical spectroscopy to characterize the quasicrystalline state of solid matter is reviewed. After a general, chronological survey of existing mechanical spectroscopy studies, which include elastic properties as well as various relaxation phenomena between lowtemperature tunneling processes and high-temperature background damping, three subjects are considered in more detail: (i) the nature of intrinsic relaxation phenomena, including relaxation peaks in Al-Pd-Mn single quasicrystals, (ii) hydrogen-induced loss peaks in Zr/Ti-based quasicrystals and their use as a probe, and (iii) the study of nano-quasicrystalline structures and amorphousquasicrystalline transitions. It is shown that by combined studies of different elastic and anelastic phenomena, mechanical spectroscopy can be a valuable tool to obtain information about the nature and motion of defects, about the type of local atomic order, and about phase transformations and different processes leading to the formation of quasicrystalline order.
The Snoek-Köster (SK) Relaxation and Dislocation-Enhanced Snoek Effect (DESE) in Deformed Iron
Authors: Magalas Leszek B.
Published: March 2009

The Snoek-Köster (SK) relaxation and the dislocation-enhanced Snoek Effect (DESE) in deformed ultra-high purity Fe-C alloys and industrial low-carbon cold-rolled steel sheets as well as a quantitative comparison between experimental data and computer simulations have been presented.
Determination of the Logarithmic Decrement in Mechanical Spectroscopy
Authors: Magalas Leszek B.
Published: March 2009

The comparison between the classical methods and a new algorithm OMI used to compute the logarithmic decrement is reported. The OMI algorithm is tested in the computation of the logarithmic decrement from exponentially damped harmonic oscillations. The OMI algorithm yields high precision in the computation of the logarithmic decrement and the resonant frequency, and the smallest dispersion of experimental points.
Principles of Microstructural Formation in Semi-Solid Metal Processing
Authors: Flemings Merton C. , Martinez R. Andy
Published: March 2009

The essential first step in semi-solid forming is to obtain a high grain
density during the initial stages of solidification of an alloy melt. This is usually done
by a combination of cooling and convection. If the grain density is too low, the
resulting structure is one of conventional coarse dendrites, unsuitable for semi-solid
forming. At higher grain densities, fine dendrites grow that can be coarsened to a
spheroidal structure in a short enough time to be of practical interest for semi-solid
forming. If the initial grain density is still higher, the grains grow in a fully spheroidal
manner. Thus there are two distinctly different paths to formation of the desired
structure: 1) coarsening of fine dendrites, and 2) direct spheroidal growth. We are
beginning to understand quantitatively the conditions necessary to form spheroids in
these two different ways.
SSM Technology Unit Design Requirements
Authors: Bocharov Yu.A. , Semenov B.I. , Kushtarov K.M. , Gladkov Yu.A. , Khizhniakova L.V.
Published: March 2009

Technology requirements for a billet micro globular structure development and following
deformation are the basic inputs in a conceptual forging equipment design. The R&D team has
studied the features of the Aluminum alloy thixoprocess experimentally on a crank press as well as
with a help of computer simulation and have formulated requirements for SSM technology CNC
prototype unit development.
Numerical Modeling of Planar Flow Casting Process
Authors: Cho Kee Hyeon , Lee Kee Ahn , Kim Moon Chul , Yoon Joong Mook
Published: March 2009

This study sought to examine the effect of various process parameters on the thickness of
the amorphous strip produced by Planar Flow Casting (PFC), which is used to solidify molten
metals rapidly. The processes were simulated via fully coupled fluid flow, heat transfer, and
solidification models. The temperature distribution and velocity profile of melt in the computational
domain with given process parameters were investigated according to various melt inlet
temperatures, size of gap between nozzle slots, rotating wheel, and ejection pressure. In general,
stable shaping of ribbons was obtained given a heat transfer coefficient of 100 cal/cm2/sec/°C. Strip
thickness was found to decrease with the pouring temperature of melt. The results evaluated based
on the numerical model were verified based on experimentally measured data.
A Study on the Methodology of Safety Diagnosis for Urban Railway Vehicle
Authors: Chung Jong Duk , Han Seok Yoon , Chun Hong Jung
Published: March 2009

Engineering safety diagnosis of crashed subway electric multiple units (EMUs) was
conducted for safety assessment. Several advanced engineering analysis techniques including
nondestructive evaluation (NDE) techniques and stress and structural analyses programs, were
performed for better understandings and exploration of failure analysis and safety concerns. NDE
techniques such as ultrasonic testing and magnetic particle testing, were used to detect
manufacture-induced and/or in-service defects and collision-induced flaws, and measure the
dimensions of deformed and non-deformed parts on damaged EMUs due to a rear-end collision.
Moreover, stress and structural analyses using commercial I-DEAS software provided important
information on stress distribution and load transfer mechanisms as well as the amount of damages
during the crash. A good agreement has been found between structural analysis results and the results
of actual damages in EMUs during crash. In this investigation, various advanced engineering analysis
techniques for the safety analysis of subway EMUs have been introduced and the analysis results have
been used to provide the critical information for the safety assessment of crashed EMUs.
Flash Design for Automatic Transfer System of Bearing Hub in Hot Forging Process
Authors: Lee Sang Kon , Byun Hyun Sang , Kim Byung Min , Ko Dae Cheol , Kang C.G.
Published: March 2009

The aim of this study is to design flash geometry of bearing hub to apply the automatic
transfer system in hot forging process. The flash geometry is very important in hot forging process
because the flash geometry effects on the metal flow, material losses, forging load, die pressure and so
on. In this study, the problem of designing the flash geometry is studied with flash thickness and width
considering the maximum die pressure to apply an automatic transfer system in hot forging process
for bearing hub. The numerical analysis was conducted by means of the commercial S/W DEFORM.
On the basis of numerical analysis the flash geometry of hot forging die was redesigned, and
experiment was conducted. From the experimental results, it was possible to produce bearing hub
with an automatic transfer system without any deterioration of die lifetime.
Comparative Evaluation of TiN/CrN, AlN/CrN, TiAlN/CrN Multilayer Films for the Use of Semi-Solid Processing of Cu Alloys
Authors: Lee Sang Yong , Lee Sang Yul
Published: March 2009

In order to investigate the effect of PVD coatings on the performance of proto-type high
temperature mold and to identify the best candidate thin films for Cu semi-solid processing,
TiAlN/CrN multilayer coatings with various superlattice periods was synthesized using a closed field
unbalanced magnetron sputtering method with separate Cr and TiAl and characteristics of these films
were compared with those from TiN/CrN and AlN/CrN films in terms of microstructure,
nanoindentation hardness, and oxidation test at 900 in air. TiN/CrN film showed the best
mechanical properties but their oxidation resistance, the most critical property for high temperature
semi-solid processing was the poorest. Therefore TiAlN films with a superlattice period of 6.1nm
which has intermediate plastic deformation resistance with the best oxidation resistance were
considered to be the best candidate out of three different films studied in this work.
Microstructure Evolution of AZ91D Magnesium Alloy Semi-solid Billets Prepared by a New SIMA Method
Authors: Jiang Ju Fu , Luo Shou Jing
Published: March 2009

By using equal channel angular extrusion (ECAE) as strain induced step in strain induced
melt activated (SIMA) and completing melt activated step by using semi-solid isothermal treatment, a
new SIMA method is introduced firstly. The results show that semi-solid billet with highly spheroidal
and homogeneous grains with the average grain size of 20μm can be prepared by new SIMA method.
High mechanical properties, such as ultimate tensile strength of 321.8MPa and elongation of 15.2%
are obtained in magazine plate components thixoforged using semi-solid billet prepared by new
SIMA.
TEM Study of a Creep-Resistant Mg-5Al-2Sr Alloy after Semisolid Molding
Authors: Czerwinski Frank , Zielinska-Lipiec Anna
Published: March 2009

Transmission electron microscopy (TEM) was used to assess the microstructural changes
accompanying semisolid molding of a creep resistant Mg-5%Al-2%Sr alloy. It was revealed that the
processing created thixotropic morphologies with globular solids of α-Mg, having well-developed
sub-structures. The quickly-solidified liquid fraction, enriched in Al and Sr, led to the formation of
increased volumes of a lamellae type Al4Sr phase, surrounding the secondary α-Mg. Traces of
Mg17Al12 still existed, predominantly as irregular shape compounds located mainly in grain
interiors. Both the primary solid and high melting point precipitates of Mn-Al modified with Sr,
acted as nucleation substrates for secondary α-Mg grains.
Investigation on Fracture Mechanism of A356 during Thixo-Forging
Authors: Wang Kai Kun , Kopp R. , Hirt Gerhard
Published: March 2009

Transmission electron microscopy (TEM) was used to assess the microstructural changes
accompanying semisolid molding of a creep resistant Mg-5%Al-2%Sr alloy. It was revealed that the
processing created thixotropic morphologies with globular solids of α-Mg, having well-developed
sub-structures. The quickly-solidified liquid fraction, enriched in Al and Sr, led to the formation of
increased volumes of a lamellae type Al4Sr phase, surrounding the secondary α-Mg. Traces of
Mg17Al12 still existed, predominantly as irregular shape compounds located mainly in grain
interiors. Both the primary solid and high melting point precipitates of Mn-Al modified with Sr,
acted as nucleation substrates for secondary α-Mg grains.
Optimal Filling of Test Dies for Evaluating Properties of Semi-Solid Alloys
Authors: Loong Chee Ang , Zheng Chang Qing
Published: March 2009

An investigative study was conducted on how two different dies designed to produce
sound specimens for evaluating mechanical properties of semi-solid alloys could be filled
optimally. The first die contains one cavity that produces a wedge with a sectional thickness varying
from 19.05 mm (0.75 in) to 9.52 mm (0.375 in). The second die contains four cavities fed by a
single runner, producing ASTM-type round bars with a diameter of 9.52 mm (0.375 in).
Experiments were undertaken to cast partial and complete shots of A356 alloy test specimens under
controlled injection conditions. Flow patterns developed from the moment the alloy entered the
cavity were noted, including difficulties experienced in balancing flow in the four-cavity die.
Microstructural abnormalities were observed in the bar specimens examined using optical and
electron microscopy. It was found that control of filling and solidification in the wedge die was
much easier and specimens produced did not result in any significant alloy segregation.
Research Progress of Semi-Solid Processing in China
Authors: Luo Shou Jing , Jiang Ju Fu , Li Yuan Fa
Published: March 2009

There have been five academic conferences organized by the chairman of semi-solid
processing academic committee, Prof. Shoujing Luo, in China since 2000. Based on the
achievements of the five academic conferences, six aspects of research progress of semi-solid
processing in China will be discussed here by the authors, which includes the research on
fundamental theories of semi-solid processing, that is, theories of high-pressure solidification,
plastic deformation densification and rheological filling; the research on technological theories of
semi-solid processing, that is, theories of preparation of semi-solid slurries or billets and their
spheroidization, theories of thixoforging and controlling of technological parameters, theories of
double controlling of semi-solid die casting and semi-solid die forging and their numerical
simulation; the research on characterization of semi-solid metal and their design; the application
present status and potential prediction of semi-solid processing; present status of academic
organization, academic communication and cultivating persons and the differences between the
other countries and China. The research results show that China is a large country for metal
processing, but China isn’t a strong in metal processing. As with other processing technologies,
under the support the government foundations and other funds, more research work should be done
in semi-solid processing and originality innovation and key technologies on preparation semi-solid
slurries or billets and forming must be completely successfully in order to improve the competitive
powder of semi-solid processing. It is should be noted that semi-solid processing will become a
important forming method of simple, high efficient, low cost and good quality in the fields of
materials processing.
Numerical Simulation of Pressure Influence on Workpiece Properties during Thixoforging
Authors: Du Zhi Ming , Shan Wei Wei , Cui Yun Tao , Peng Qiu Cai , Hu Lian Xi
Published: March 2009

Numerical simulation of pressure influence on the relative densities of both solid and
hollow cylindrical workpieces during Thixoforging was carried out by using ANSYS software. The
results showed that there was a big difference in relative density between different points within the
workpiece during Thixoforging with the use of a single punch. Therefore, partial feeding with the
help of assembly punches was proposed to improve workpiece density uniformity and properties,
and the effectiveness of this approach was well-demonstrated by numerical simulation.
In Situ Observation of SSM Microstructure Formation during Cooling Slope Casting of an NH4Cl-H2O Alloy with Vibrating the Slope
Authors: Huang Wei Dong , Wang Wen Li , Lin Xin , Wang Meng
Published: March 2009

Vibrating the slope during cooling slope casting of a metallic alloy has shown helpful for
causing the microstructure more spherical and thinner in a previous research by the present authors.
This paper gives results from a direct observation of the SSM microstructure formation during
cooling slope casting of an NH4Cl-H2O alloy with vibrating the slope. It is found that the vibration
exerted to the slope can break down the solidification shell formed at the surface of the slope
through rapid chilling and produce effectively fine globular grains in the microstructures. The main
factors affecting the fine grain formation include the chilling extent, frequency and amplitude of the
vibration of the slope, and the superheat of the alloy melt, respectively. The higher vibration
frequency and amplitude, the lower superheat of the alloy melt, and the lower chilling temperature
will help the formation of finer globular grains.
Effect of Slope Plate Variables and Reheating on the Semi-Solid Structure of Al Alloys
Authors: Ashouri S. , Nili-Ahmadabadi Mahmoud
Published: March 2009

Semi-solid forming (SSF) involves alloys with non-dendrite microstructure that contain spherical
solid particles in the liquid matrix. This process is generally divided into three main steps: feedstock
manufacturing, reheating and forming.
Feedstock has the main effect on the cost and quality of product. Many researches have been carried
out to reduce the cost of feedstock manufacturing. Slope plate is a simple semi-solid process that
can reduce the cost of feedstock. In this study a Cu plate with water and without water circulation
was used to investigate the effect of pouring temperature, cooling rate during casting and
solidification in the mold on the microstructure. Cast ingots with optimized microstructure were
reheated in various time and temperatures in semi-solid region to obtain kinetics of globularization
and solid grain growth.
Kinetics of Coarsening and Solid Sphericity during Reheating of Ductile Iron and Al Alloys
Authors: Babaghorbani P. , Salarfar S. , Nili-Ahmadabadi Mahmoud
Published: March 2009

Reheating process in the semi-solid state is a very important step in the thixoforming
process. In this research semi-solid ductile cast iron and Al alloys (Al-2.5Si, Al356) prepared by
inclined plate method, were reheated to examine the effect of reheating conditions on the
microstructure and coarsening kinetics of the alloys. For ductile cast iron, solid fraction at different
reheating temperatures and holding times was obtained and based on these results the optimum
reheating temperature range was determined. In the case of Al alloys increase of holding time in the
semi-solid state, leads to increase of liquid fraction, solid grain size and improvement of sphericity
of solid particles. In addition, the results show that coarsening kinetics of microstructures of both
alloys during reheating was diffusion controlled and can be mostly treated by Ostwald ripening
theory.
Influence of Experimental Parameters on Properties and Microstructure of the Steel X210CrW12 in the Semi-Solid State
Authors: Fraipont Celine , Püttgen Wolfgang , Bleck Wolfgang , Lecomte-Beckers Jacqueline
Published: March 2009

This paper deals with the examination of the steel grade X210CrW12 and its suitability
for Thixoforming. In the semi-solid state, the microstructure of this steel consists of a homogeneous
distribution of globular particles surrounded by liquid. Additionally, carbides are stabile up to
fraction liquid contents of approximately 40%. After quenching, this steel reveals a globular
austenitic microstructure with eutectic (former liquid phase) at the grain boundaries. Compression
tests permit to determine the influence of different process parameters on the properties and the
material behaviour in the semi-solid state. Their influence on the microstructure was investigated
but not yet highlighted. Further investigations on this steel allow a fine-tuning to establish optimal
process windows of the different thixoforming- and rheoforming- routes.
Phase Segregation Susceptibility of ZA27 Alloy at Different Shear Rates
Authors: Mola Javad , Aashuri Hossein , Shalchi Amirkhiz B.
Published: March 2009

Back extrusion technique was employed to characterize phase segregation tendency of
mechanically stirred ZA27 alloy at different deformation rates. Variation of segregation intensity
with ram diameter was found to follow opposite trends at low and high ram speeds. At sufficiently
high ram speeds, small rams are of better performance in minimizing segregation whereas at low
ram speeds, large rams result in less pronounced segregation. In addition, increasing ram speed
invariably decreases segregation degree. Back extrusion at very high shear rates provided via a
Drop Extruder Apparatus capable of displacing ram at speeds in excess of 1m/s results in
production of very homogeneous products in terms of solid fraction as well as size distribution of
globules.