bluuebunny/crossref_metadata_2025 huggingface dataset:
The Dimensional Change in the Sintering of a Plain Iron Powder and High-Alloyed Iron Powder Mixtures
Authors: das Neves Maurício David Martins , Filho Nelson Karsokas , Rodrigues Daniel , Salgado Lucio , Ambrozio Filho Francisco
Published: March 2009

In plain iron powder or powder mixtures sintering process, it is very important to control the dimensional change. In the sintering associated events, such as lubricant removal, atomic motion and phase transformation could change dimensions over a wide range. Dilatometric analysis has shown that most contributions in the dimensional change in the sintering of iron powder mixtures were due to the combination of several effects occurring in all stages of the processing, including the heating and cooling stages. The present paper has the objective of studying the dimensional behavior and to determine the transformation temperature of a composite powder mixture of a plain iron powder with various additions of high-alloyed steel, carbon, nickel and lubricant powders, during sintering by dilatometric analysis.
A Job Shop Scheduling Heuristic Algorithm Based on Probabilistic Model of the Search Space
Authors: Yang Hong An , Xu Ya Ping , Sun Shu Dong , Yu Jian Jun
Published: March 2009

The job shop scheduling problem is an NP-hard problem and conveniently formulated as Constraint Satisfaction Problem (CSP). Research in CSP has produced variable and value ordering heuristics techniques that can help improve the efficiency of the basic backtrack search procedure. However, the popular variable and value ordering heuristics play poor in solving the large-scale job shop scheduling problem. In this paper, a new probabilistic model of the search space was introduced which allows to estimate the reliance of an operation on the availability of a reservation, and the degree of contention among unscheduled operations for the possession of a resource over some time interval. Based on this probabilistic model, new operation and reservation ordering heuristics were defined. new operation ordering heuristic selects the operation that relies most on the most contended resource/time interval, and new reservation ordering heuristic assigns to that operation the reservation which is expected to be compatible with the largest number of survivable job schedules. Computer simulations indicate that this new algorithm yields a optimal result of FT10 benchmark job shop scheduling problem under small time cost.
Study on the Synthesis Mechanism of Nanocrystalline Diamond Thick Films
Authors: Xu Feng , Zuo Dun Wen , Lu Wen Zhuang , Song Sheng Li , Wang Min
Published: March 2009

Nanocrystalline diamond film is an excellent material for high-tech fields because of its
excellent properties. In this paper, research was carried out on the synthesis and deposition
mechanism of nanocrystalline diamond thick film in the self-made double bias hot filament
chemical vapor (HFCVD) deposited system. Double biases including positive bias on the grid
electrode on top of hot filaments and negative bias on the substrate were added to the HFCVD
system. During the deposition, nucleation and growth stages were applied alternately to control
crystalline size and improve quality. The mechanism of the deposition is discussed in detail in this
paper. The positive grid bias increases the active, decomposition and ionization of hydrogen and
methane molecules, while negative substrate bias helps positive carbon-containing ions bomb the
substrate that leads to the high nucleation density of the diamond. Raman results show that the film
prepared has high quality. And SEM results show that the film’s grain size is less than 100nm with
thickness of 50μm.
Determining and Optimizing of Guide Rolls Motion Track in Cold Ring Rolling Process
Authors: Sun Zhi Chao , Yang He , Li Lan Yun
Published: March 2009

Guide rolls play an important role in controlling both the ring circularity and the stability of
cold ring rolling process. However, it is difficult to predict and control the motion of the guide rolls
due to the complexity of process associated with the coupled effects of multi-factors. In this paper, a
reasonable controlling model of the guide rolls is proposed, and the functional relationship between
the motion track of the guide rolls and their setup parameters and process ones is established, by
which the guide rolls motion track can be determined. On this basis, a 3D-FE simulation model for
cold ring rolling is developed under the ABAQUS software environment and the effects of the initial
position and motion track of the guide rolls on the forming stability, ring circularity, rolling force, and
oscillating are investigated. Taking the forming stability and ring circularity as objects, the optimum
initial position and motion track of the guide rolls are obtained.
Research on Variation of Stress and Strain Field and Wall Thickness during Cone Spinning
Authors: Zhan Mei , Yang He , Zhang Jin Hui , Xu Yin Li , Ma Fei
Published: March 2009

Cone spinning is an advanced but complex metal forming process under coupled effects
of multi-factors. Understanding the deformation mechanism, i.e., the stresses, strains, and metal
flow in the deformation zone during the process is of great significance for optimizing the spinning
process and controlling the product quality. In this paper, based on ABAQUS/Explicit, a reasonable
FEM model for cone spinning with a single roller has been established, and the features of stress,
strain and wall thickness during the process have been obtained. The results show the following: (1)
In the beginning, large stress, large strain and the acute thinning of wall thickness localize at the
small region below the roller, then the region extends into a small ring, further it becomes a large
ring, and finally the ring will become uneven if the wrinkling occurs in the flange. (2) After
spinning, the acute thinning region locates at the midst of the wall near the bottom of the workpiece.
(3) At earlier stage of cone spinning, as a result of the acute thinning of wall thickness in the wall
zone, the unevenness of wall thickness increases sharply to a value, then it almost keeps the value at
the stable stage, and finally it will slowly increase again if the wrinkling appears in the flange. The
results are helpful for determination and optimization of process parameters of cone spinning.
Experimental Research on Machining Performance of Electrode Materials in Dry EDM
Authors: Li Li Qing , Wang Zhen Long , Guo Yong Feng , Bai Ji Cheng
Published: March 2009

Electrode materials are important factors affecting machining performances (MP) of
electrical discharge machining (EDM). Experiments using different electrode materials were carried
out in compressed air aim to realize MP of electrical discharge machining in gas (dry EDM).
Experimental results show that a minimum pulse interval exists for given parameters and tool
material. Calorific performances of tool materials are main influencing factors of MP on the
condition of thorough deionization. Copper achieves the best MP in the experimental tool materials.
Experimental results of different workpiece materials depict that material remove rate (MRR) and
surface roughness (SR) value increase with increases of discharge energy. SKD61 steel achieves the
highest MRR and SR value in the experimental materials. Material holding better performance of
heat resistant, such as titanium alloy (TC4), achieves the lowest MRR.
Analysis of Disassembled Module with Damage Model for Recycling
Authors: Ji Yong , Narita Hirohisa , Chen Lian Yi , Fujimoto Hideo
Published: March 2009

As environmental problems have become more serious, a sustainable society is necessary.
To realize the inverse manufacturing system the prime problem is how to improve the rate of reusing
the product modules. Therefore analyzing the life-time of the disassembled modules is very important
before reassembling process. In this paper, a cumulative damage model is proposed to discuss the
quality of the product that is assembled by reuse modules. It is supposed that modules suffer damages
due to shocks and fails when the cumulative damage level exceeds the failure level. Then
maintenance cost will be analyzed in order to minimize the expected maintenance cost-rate by
optimal maintenance time T and optimal number of damages N in this cumulative damage model. The
probable safe life-time of module reuse will be explored. Finally numerical examples are given to
confirm the validity of the proposed model.
MEMS R&D Trends
Authors: Jiang Cheng Yu , He Yang , Yuan Wei Zheng
Published: March 2009

Micro-Electromechanical Systems (MEMS) has been regarded as one of the most promising technologies for the 21st Century. Recently, some highlight areas attract great attention including Inertial MEMS, Optic MEMS, RF MEMS, BioMEMS, Power MEMS, and NEMS. The state of arts on MEMS research in China is briefly introduced and research activities in Northwestern Polytechnical University such as MEMS CAD tool, inertial MEMS devices, flexible substrate for MEMS integration, micro mirror, micro battery and three dimension measurement are demonstrated.
Arc Envelope Grinding of Non-Axisymmetric Aspheric Surface Using Equal-Envelope Height
Authors: Xie Jin , Xu Wei Wei
Published: March 2009

An arc envelope grinding method for non-axisymmetric aspheric surface was proposed in
order to achieve the mould core used for the precision injection molding of optic reflector. In
grinding, the arc-shaped diamond grinding wheel trued on CNC grinder was used to envelope
workpiece and generate curve surface, and the spacing distance between tool paths is controlled by the
equal-envelope height between wheel and workpiece. In this paper, arc envelope grinding principle
was investigated in connection with wheel coordinate calculation and tool path number. The
theoretical analysis and grinding experiment showed that arc envelope grinding may improve form
grinding efficiency especially for large curvature and smoothness of ground surface and a smooth
curve surface can be produced when the equal-envelope height is less than a certain value.
Fabrication of Microelectrode by Current Density Control in Electrochemical Micromachining
Authors: Zhu Bao Guo , Wang Zhen Long
Published: March 2009

The fabrication technology of microelectrode in electrochemical micromachining (EMM)
was presented. The high frequency short pulses current and current density control between the
cathode and anode were synthetically utilized. The mechanism of pulses EMM was expatiated firstly.
The shaping principle of microelectrode was analyzed. The current density control strategy was
proposed based on the fundamental experimental behavior of electrochemical machining current with
the gap variance. Then an experimental setup for EMM is constructed, which has machining process
detection and current density control functions, also a pulses power supply and a control computer are
involved in. After the technologic experiment analyzed, some microelectrodes with nice surface are
fabricated successfully. This method could provide the simple electrode for further electro-machining
or micro probe for scanning probe microscopy. Preliminary experimental results show the feasibility
of EMM and its potential capability for better machining accuracy and smaller machining size.
Study on Surface Integrity of an Ultra-High Strength Alloy in HSC Process
Authors: Long Zhen Hai , Wang Xi Bin , Zhao Wen Xiang
Published: March 2009

Aiming to study the surface integrity of an ultra-high strength alloy in high speed milling process, 2K factorial design experiments were conducted to explore the effects of cutting parameters, such as cutting velocity, feed rate and depth of cut, on microstructure, microhardness and residual stress in the sub-surface layer. The following conclusions could be drawn from this paper within the range of cutting conditions: The cutting parameters could significantly influence the microstructure and microhardness in the surface and sub-surface layers, and the original fine martensite of the surface and sub-surface layer might be transformed into the over-tempered martensite, under-tempered martensite, secondary troostite, and tempered sorbite; Compressive residual stress distributions with different maximum stress values in the sub-surface layer of machined surfaces could emerge in high speed cutting process; the properly arranged cutting condition could achieve ideal surface characteristics and surface integrity.
A Reappraisal of Various Compacting Processes for Wasted Expandable Polystyrene (EPS) Foam
Authors: Seo Jung Min , Hwang Beong Bok
Published: March 2009

Once expandable polystyrene (EPS) foam has been used out, its high volume-to-weight
ratio becomes a serious problem, and it is now prototypical high-bulk/non-burnable landfill problem.
This is one of main obstacles for EPS foam to be recycled. This paper is concerned with volume
reduction method for wasted EPS foam. The analysis is focused on the description of importance of
volume reducing method for EPS foam. Wasted EPS foam has not been recycled effectively since its
volume to weight ratio is extremely high. The large volume of EPS has prevented from its proper
recycling because of high cost of transportation to recycling plant. In this reason, successful recycling
of wasted EPS foam results directly from successful volume reduction of wasted EPS foam in proper
manner. This paper deals with various existing methods for volume reduction of wasted EPS foam.
Six existing processes of volume reduction for wasted EPS has been analyzed qualitatively and
compared each other in terms of expected polystyrene (PS) characteristics after volume reduction,
cost effectiveness of each process, possible effects on environment caused by the volume reduction
process, and applicability to possibly recycled products. The methods analyzed in this paper include
thermal, solvent, far infrared, pulverization, and mechanical compaction. Analysis was concentrated
to compare each process mostly in qualitative manner among existing processes.
Prediction of Surface Quality for Silicon Carbide Wheel Grinding of Silicon Nitride
Authors: Xu Li Ming , Shih Albert J. , Shen Bin , Ma Chun Xiang , Hu De Jin
Published: March 2009

The experimental results for silicon carbide (SiC) wheel with fine grit size grinding of
silicon carbide (Si3N4) revealed that the grinding parameters affect not only the ground silicon
nitride surface roughness, but also the degree of surface damage. There exists complex non-linear
relationship between the grinding parameters and surface quality. Better surface roughness doesn’t
surely mean less surface damage. A method of prediction of grinding quality based on support
vector regression is then presented according to the condition of small samples. The result shows
the prediction accuracy based on this method is obviously higher than neural network, which
provides an effective way for optimizing the grinding parameters to ensure the grinding quality as
well as grinding efficiency while grinding of silicon carbide using conventional abrasive.
Research on the Modeling Algorithm for the Camber of Large-Sized Revolving Parts
Authors: Ruan Zhen , Hu De Jin , Shi Lun , Wang Hai Li , Liu Mao Sheng
Published: March 2009

Present modeling algorithm for large-sized revolving parts’ camber can not ensure the
smoothness, so a new modeling algorithm based on NURBS Curve was proposed in this study. In
detail, the new modeling algorithm is as following: Firstly transfer these discrete points, which are
measured along the part’s axial lead by equal distant, into a weighting unity sequence. Secondly filter
this sequence by wavelet de-noising algorithm. Thirdly replace the discrete points’ amplitudes by the
corresponding weights of filtered sequence, thus yield a group of new discrete points. Lastly calculate
the control vertexes and weighting factors by local rational interpolation algorithm, and construct a
spatial NURBS Curve through the new discrete points to obtain the model of large-sized revolving
parts’ camber. It was experimentally confirmed that this model can represent drilling stem’s camber
smoothly and improve its pressure straightening precision.
Microstructure and Mechanical Properties of Nano-Scale Al2O3 Toughened Ti (C,N) Matrix Cermet Tool Materials
Authors: Huang Chuan Zhen , Wang Jun , Xu Li Qiang , Wang Sui Lian , Liu Han Lian
Published: March 2009

Advanced Ti(C, N) matrix cermet tool materials with higher mechanical properties are
successfully developed by dispersing nano-scale Al2O3 powder into the micro-scale Ti(C, N) matrix
and Ni-Mo bonding phases powder. The effect of the content of nano-scale alumina on the
microstructure and mechanical properties of micro-scale Ti(C, N) matrix cermet tool materials are
investigated. The research results show that a type of Ti(C, N) matrix cermet tool material has the
most optimal flexural strength of 900MPa, Vickers hardness of 17.4GPa and fracture toughness of
9.95MPa.m1/2 when the content of nano-scale alumina is 12% in term of mass. It is found from the
microstructure analysis that the main reason of the mechanical properties improvement is the grain
fining effect caused by nano-scale Al2O3.
Fabrication of Three-Dimensional Micro-Structures with Two-Photon Absorption by Femtosecond Laser
Authors: Zhou Ming , Yang Hai Feng , Liu Li Peng , Cai Lan
Published: March 2009

The photo-polymerization induced by Two-Photon Absorption (TPA) is tightly confined in the focus because the efficiency of TPA is proportional to the square of intensity. Three-dimensional (3D) micro-fabrication can be achieved by controlling the movement of the focus. Based on this theory, a system for 3D-micro-fabrication with femtosecond laser is proposed. The system consists of a laser system, a microscope system, a real-time detection system and a 3D-movement system, etc. The precision of micro-machining reaches a level down to 700nm linewidth. The line width was inversely proportional to the fabrication speed, but proportional to laser power and NA. The experiment results were simulated, beam waist of 0.413μm and TPA cross section of 2×10-54cm4s was obtained. While we tried to optimize parameters, we also did some research about its applications. With TPA photo-polymerization by means of our experimental system, 3D photonic crystal of wood-pile structure twelve layers and photonic crystal fiber are manufactured. These results proved that the micro-fabrication system of TPA can not only obtain the resolution down to sub-micron level, but also realize real 3D micro-fabrication.
Numerical Simulation on Thixoforming of Wrought Magnesium Alloy
Authors: Yan Hong , Xu Chen , Chen Guo Xiang
Published: March 2009

The thixoforming of wrought magnesium alloy was analyzed with computer numerical
simulation based on rigid plastic/rigid viscoplastic finite element method. The simulated parameters
were chosen and depended on the constitutive model of semi-solid AZ61 alloy that was established
using the multiple nonlinear regression method in our prior literature. Thixo mechanical properties
of semi-solid AZ61 alloy in high solid volume fraction were also analyzed. Behaviors of metal flow
and temperature field were obtained, which were also compared with experimental data in literature.
Research showed that the hard deformation magnesium alloy had great filling ability in semi-solid
state, and the stress and strain distributions in workpiece after thixoforming were uniform. The
semi-solid thixoforming technology has taken priority of the traditional processing.
Dynamic Monitoring and Intelligent Dressing of Diamond Wheel for Precision Curve Grinding
Authors: Wan Da Ping , Hu De Jin , Wang Hai Feng , Zhang Yong Hong
Published: March 2009

This paper deals with an application for achieving precision curve grinding by automatic dressing and compensation of diamond wheel wear through non-contact measuring method. A realtime vision measurement combined with vibration analysis method for the wear of a grinding wheel is presented. The wear condition is evaluated by analyzing the topography changes of the wheel surface and the vibration signals in the grinding process. A kind of PC-based integrated control system with dynamic monitoring and automatic dressing function is investigated, and the control algorithm is also proposed. The benefits of the proposed methods are confirmed by the grinding experiments. Dynamic monitoring of the wheel facilitates determining the optimum dressing amount and interval. A much higher abrasive machining precision and efficiency are attained by the real-time error measurement and compensation arrangement.
Effects of Crystal Grain Size and Particle Size on Core Loss for Fe-Si Compressed Cores
Authors: Takemoto Satoshi , Saito Takanobu
Published: March 2009

Core loss of soft magnetic powder cores have been focused on to achieve high efficiency
of power supplies. In this study the effects of crystal grain size on core loss were investigated by
changing heat treatment conditions. It was found that core loss is influenced by crystal grain size
because eddy current loss decreased and hysteresis loss increased by making crystal grain size
smaller, and it is also influenced by the frequency and particle size.
Shrinkage Free Sintering of Low Temperature Cofired Ceramics by Glass Infilteration
Authors: Yeo Dong Hun , You Jung Hun , Shin Hyo Soon , Kim Jong Hee
Published: March 2009

The shrinkage variation of Low Temperature Cofired Ceramics(LTCC) limits the size of
the substrates that impose limitations on embedded passive components. This paper focuses on the
method of minimizing or controlling planar shrinkage and reducing distortion during firing. The
laminated sheets of alumina and glass were sintered at varying temperature, and depending on the
amount of the glass ceramics. When the sintered of multi-layer structure with Al2O3/Glass/Al2O3,
the glass infiltrated entirely into Al2O3 layer at the temperature of about 950°C or higher.
Sintering Behavior of TiC-Fe Based Composite Fabricated by Spark Plasma Sintering Using TiH2 Graphite Powders
Authors: Bae Sung Yeal , Ahn In Sup , Cho Ho Jung , Kim Chul Jin , Park Dong Kyu
Published: March 2009

TiC particulate reinforced Fe matrix composite compacts with controlled interfacial reaction was processed by spark plasma sintering after mechanical alloying. Milled powders were fabricated for 1-5 hours by spex shaker mill with the ball to powder ratio of 25:2. Metal matrix composites (MMCs) based on the Fe-40%TiC system can be synthesized by spark plasma sintering of the D’AE powders with TiH2-graphite powders under vacuum in the temperature range 1273-1473K for 5-20 min. TiC phase was formed by self combustion reaction with temperature increase. The specimen that was formed by sintering Fe-TiC powders displayed a microstructure of uniformly dispersed TiC grain in a continuous metal matrix. The densifications of the TiC-Fe materials were increased as the heat-treatment holding time increasing. In the same time, relative density and hardness of TiC-Fe sintering materials was increased.
Effect of FeNi30 Powder Catalyst by Water Atomizing on Synthesis High-Grade Diamond
Authors: Cheng Dong Kai , Ma Hong Qiu , Cao Dan , Ding Fu Chang
Published: March 2009

This paper described the preparation method for composing high-grade synthetic
diamond by water atomizing using FeNi30 powder catalyst.The FeNi30 powder was corroded by
the 100Mpa super high-pressure water atomizing technique and selecting organic RY corrosion
inhibitor. Contrast test of the original FeNi30 powder and the treated FeNi30 powder on synthetic
diamonds were conducted under super high-temperature and high-pressure using cubic press. The
result shows that after the FeNi30 powder was corroded,the FeO phase and Fe3O4 phase could not
longer be found by X-Ray analysis.Furthermore,the oxygen content of the powder increased up to
100PPM under the natural condition for one year. After the powder was mixed with graphite
powder, diamond could be made by isostatic pressing method. Its color became darker and its TTI
value increased slightly. However, its penetrability was still different from the high-grade synthetic
diamond made by gas atomizing FeNi30 powder catalyst.
Preparation and Properties Study of Cu-MoSi2 Composites
Authors: Yi Xiaoou , Xiong Wei Hao , Li Jian
Published: March 2009

The particulate dispersive strengthened Cu-MoSi2 composites were prepared by a powder
metallurgy process with aim to develop novel copper based composites of reasonable strength, high
thermal conductivity and low thermal expansion coefficients. Compacted samples were sintered to
over 90% of theoretical density. Microstructure of the composites was investigated by SEM while
mechanical properties such as tensile strength, elongation and thermal properties such as thermal
conductivity and thermal expansion coefficient (CTE) of the composites were examined as a
function of the MoSi2 content and the process of fabrication. A comparative analysis of the
mechanical and thermal properties of various Cu-matrix composites currently in use was given and
the strengthening mechanisms for the Cu-MoSi2 composites were discussed.
The Effect of Cooling Rate on the Structure and Mechanical Properties of Fe-3%Mn-(Cr)-(Mo)-C PM Steels
Authors: Sulowski Maciej , Cias Andrzej , Frydrych Hanna , Frydrych Jerzy , Olszewska Irena , Golen Ryszard , Sowa Marek
Published: March 2009

The effect of different cooling rate after sintering Mn steels at 1120°C and 1250°C by
adding Cr and Mo was investigated. Pre-alloyed Astaloy CrM and CrL, ferromanganese and graphite
powders were used as the starting powders. Pressing was carried out in steel rigid dies to achieve
the same density in the range of 6.8-7.2 g/cm3. During pressing rectangular and ISO 2740 specimens
were prepared. Then, green compacts were sintered at 1120°C and 1250°C for 60 minutes in
atmosphere with different H2/N2 content and cooled at a cooling rate 1.4°C/min (slow, furnace cooling)
and 65°C/min (convective cooling). Convecitve cooled specimens were subsequently tempered
at 200°C for 60 and 240 minutes. To investigate the mechanical properties: UTS, elongation A, R0.2
yield offset, TRS, impact toughness IT and hardness measurements results were examined. After
the mechanical examination, the microstructure of Fe-Mn-Cr-Mo-C PM steels were studied by optical
microscopy.
Influence of High-Energy Milling and Sintering Cycle on Obtaining TiAl from Elemental Ti and Al Powders
Authors: Esteban P.G. , Gordo Elena , Ruiz-Navas E.M.
Published: March 2009

The present work studies the influence of high-energy milling (HEM) and sintering cycle
of Ti and Al powders on the obtainment of TiAl. This study shows that HEM modifies the diffusion
processes during the sintering stage. The ignition temperature of the exothermic reaction (SHS) that
occurs between Ti and Al, was considered as the key parameter of the sintering process, leading to
the study of sintering cycles that avoid uncontrolled processes caused by the SHS reaction. The
samples were obtained by cold uniaxial and isostatic pressing, pre-sintered at different
temperatures, and then heated up to the sintering temperature. This study also shows the effect of
powder additions processed by HEM on the sintering behavior of blended elemental Ti and Al
powder compacts.
Compressive Behavior of 7xxx Series Al Composites Reinforced with Al2O3
Authors: Seo Young Ik , Min Kyung Ho , Lee Kyu Hwan , Kim Young Do
Published: March 2009

Mechanical properties of 7xxx series Al metal matrix composite (MMC) powders
containing different amounts of ceramic were investigated. The ceramic contents of the starting
powders were 5 wt.% or 10 wt.%. 7xxx Al blended powder was used for comparison. The powders
were uniaxially cold compacted using a cylindrical die with a compacting pressure of 250 MPa and
were sintered at 620oC in a dry N2 atmosphere for 60 min. The heating rate was varied up to
100oC/min. For the heat treatment, sintered parts were solution treated at 475oC and aged at 175oC.
Compression tests were conducted to reveal the effect of Al2O3 particle content on the mechanical
properties of the composites. Fractography was examined using a scanning electron microscope.
Effect of Cutting Tool Materials on Surface Roughness and Cutting Forces in Machining of Al-Si3N4 Composite Produced by Powder Metallurgy
Authors: Ozcatalbas Yusuf , Bahceci Ersin , Turker Mehmet
Published: March 2009

In this study, aluminum-based composites reinforced with various amounts of α-Si3N4
were produced by powder metallurgy (P/M). The machinability properties of MMCs were
determined by means of cutting forces and surface roughness. Machining tests were carried out by
using PCD and K10 cutting tools. Increasing of Si3N4 volume fraction in the matrix resulted in a
decrease of the surface roughness and turning forces. PCD cutting tools showed better cutting
performance than K10 tools. Surface roughness and turning forces were decreased significantly by
PCD tool.
Studies on Preparation of Ti3SiC2 Particulate Reinforced Cu Matrix Composite by Warm Compaction and Its Tribological Behavior
Authors: Ngai Tungwai Leo , Xiao Zhi Yu , Wu Yuan Biao , Li Yuan Yuan
Published: March 2009

Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3 g/cm3 (a relative density of 93%). Performances of these conventionally compacted materials are substantially lower than their full density counterparts. Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials, was employed to develop a Ti3SiC2 particulate reinforced copper matrix composite with high density, high electrical conductivity and high strength. In order to clarify the warm compaction behaviors of copper powder and to optimize the warm compaction parameters, effects of lubricant concentration and compaction pressure on the green density of the copper compacts were studied. Copper compact with a green density of 8.57 g/cm3 can be obtained by compacting Cu powder with a pressure of 700 MPa at 145°C. After sintered at 1000°C under cracked ammonia atmosphere for 60 minutes, density of the sintered compact reached 8.83 g/cm3 (a relative density of 98.6%). Based on these fabrication parameters a Ti3SiC2 particulate reinforced copper matrix composite was prepared. Its density, electrical conductivity, ultimate tensile strength, elongation percentage and tribological behaviors were studied.
Fatigue Behaviour of Railway Wheel Steels under Constant and Variable Amplitude Loading
Authors: Walther F. , Eifler Dietmar
Published: March 2009

In this paper, the influence of the microstructure on the fatigue behaviour of specimens
from defined rim positions of original railway wheels R7 (SAE 1050) and tyres B6 (SAE 1065) is
characterised under constant and variable amplitude loading. Due to the industrial heat treatment
and the component size, the ferrite fraction and the cementite lamellae spacing of the ferriticpearlitic
microstructures increase with increasing tread distance. The microstructural gradients
influence the fatigue behaviour in a characteristic manner. Mechanical stress-strain hysteresis,
temperature and electrical resistance measurements were performed. Temperature and electrical
resistance data represent the actual fatigue state in highly stressed volume parts and are not related
to a gauge length. Furthermore the electrical resistance is qualified to detect a proceeding fatigue
damage in load-free specimens and components. For variable amplitude loading a new testing
procedure was applied, which combines any kind of near-service load spectrum with short single
step measuring sequences. The plastic strain amplitude, the temperature and the electrical resistance
data of each single step sequence are plotted in cyclic ‘deformation’ curves and represent the sum of
microstructural changes caused by near-service loading. The substitution of the plastic strain
amplitude by the changes of the temperature and the electrical resistance leads to modified Morrow
and Manson-Coffin curves. Electron microscopic investigations allow to interpret the measured
fatigue data on the basis of microstructural details.
Influence on Annealing Treatments on Twins in Magnesium Alloy AZ31
Authors: Backx Petra , Petrov Roumen H. , Kestens Leo
Published: March 2009

This research looks at the influence of annealing treatments on twins in magnesium alloy
AZ31. Samples containing different twin fractions are created in order to examine the influence of
the initial structure on the annealing behavior. It is seen that twins can both expand, taking over an
entire grain, or shrink, leaving completely untwinned grains. The grains, containing expanding
twins, are found to contain, in general, only one twin variant and limited slip deformation after twin
formation. The grains containing shrinking twins, on the contrary, are seen to contain different twin
variants and have undergone more slip deformation after twinning.
The Microstructure Evolution of Copper and Gold Bonding Wires during Annealing
Authors: Cho Jae Hyung , Rollett Anthony D. , Oh Kyu Hwan
Published: March 2009

Copper and gold bonding wires were characterized and compared using electron
backscatter diffraction (EBSD). During drawing, <111> and <100> fiber textures are the main
components in the wires and shear components are mainly located under the surface. Grain average
misorientation (GAM) and scalar orientation spread (SOS) of the <100> component in copper and
gold bonding wires are lower than those of the <111> or other orientations. The bonding wires
experience three stages of microstructural changes during annealing. The first stage is subgrain
growth to keep elongated grain shapes overall and to be varied in aspect ratio with annealing time.
The grain sizes of the <111> and <100> components increase during annealing. The volume fraction
of the <100> component increases whereas that of the <111> decreases. The second stage is
recrystallization, during which equiaxed grains appear and coexist with elongated ones. The third
stage is grain growth which eliminates the elongated grains and enlarges equiaxed grains. The <111>
and <100> grains compete with each other and the <111> grains grow faster than the <100> grains
during the third stage.
Intercritical Annealing Behaviour of an Ultrafine Grained C-Mn Steel Obtained by Hot Torsion Deformation
Authors: Azevedo G. , Barbosa Ronaldo , Pereloma Elena V. , Santos Dagoberto Brandão
Published: March 2009

Several studies concerning ferrite grain refinement have been developed in recent the last
years due to the recognised influence of such microstructures on steels properties. This work was
focused on the evaluation of the microstructure and mechanical properties of an ultrafine grained CMn
steel obtained by hot torsion deformation and intercritical annealing. After 5 min soaking at 900
and 1200°C, the samples of low carbon steel were quenched and then reheated. Hot torsion
deformation was conducted at temperatures of 700 or 740°C. The torsion schedule consisted of 7
isothermal passes leading to a total true strain of ≈1 and generating an ultrafine and inhomogeneous
microstructure with grain sizes of the order of 1-m, formed by strain-induced dynamic
transformation (SIDT). The samples were heated up to 800oC and held for 1, 2 and 3 h. A more
homogeneous microstructure and ferrite grain size were obtained after annealing The microhardness
tests showed the reduction in hardness with the increase in annealing time. They also highlighted
the effects of the ferrite grain size and the volume fractions of the microstructure constituents.
Texture and Microstructure Variation in Severe Plastic Deformed OFHC Cu Wires
Authors: Kalu Peter N. , Waryoba Daudi R.
Published: March 2009

The texture and microstructure resulting from heavily drawn and annealed oxygen-free high conducting (OFHC) copper wires have been investigated using several microscopical techniques including orientation imaging microscopy and nano-indentation. In the as-drawn condition, the microstructure and texture were heterogeneous across the wires, and consisted of three distinct concentric regimes: the inner core, the mid section, and the outer region. Whilst the microtexture of the inner core was dominated by a strong <111>+weak<100> duplex fiber texture, the mid section and the outer region had a comparatively weak fiber texture. Analysis using a Taylor-type viscoplasticity model revealed that the weak texture observed in this material was a direct consequence of shear deformation during drawing. The recrystallization kinetics of the wires upon isothermal annealing at various temperature was influenced by the deformation heterogeneity, and can be accurately described by a modified JMAK-Microhardness model. In this approach, the JMAK model is expressed in terms of microhardness data, from which the parameters of the different restoration kinetics were determined.
Fabrication of Nanocrystalline Superplastic ZrO2 Ceramics
Authors: Morita Koji , Hiraga Keijiro , Kim Byung Nam , Yoshida Hidehiro , Sakka Yoshio
Published: March 2009

An average particle size of d ≈ 300 nm can be reduced to a nanocrystalline size of about 10
nm or less after 400 h HEBM process. Amorphous-like phase is also observed among the
nanocrystalline particles. Using SPS, the nanocrystalline powder can successfully be consolidated
into a dense nanocrystalline ZrO2-spinel composite of d ≈ 90 nm. As compared with the data for
submicro-grain composite with d = 350 nm, nano-crystalization increased the strain rate by one order
of magnitude or lowered the deforming temperature by about 100 K.
On the Thermal Conductivity of Adhesively Bonded and Sintered Hollow Sphere Structures (HSS)
Authors: Fiedler Thomas , Öchsner Andreas
Published: March 2009

This paper is on the geometrical effective thermal conductivity of hollow metal sphere structures. Two different technologies of joining, namely adhesive bonding and sintering, are considered. The spheres are arranged in the nodes of a cubic primitive lattice and connected by an adhesive layer, respectively directly joined by sintering. Furthermore, the influence of the cell wall thickness of the spheres on the thermal conductivity is investigated.
Abnormal Grain Growth Induced by Boundary Segregation of Solute Atoms
Authors: Kim Seong Gyoon , Kim Won Tae , Park Yong Bum
Published: March 2009

Abnormal grain growth (AGG) proceeds in case that normal grain growth is inhibited. It has long been known that the inhibition involves finely dispersed particles and/or the development of specific textures. There is another strong obstacle against the grain boundary (GB) motion; the solute atoms can reduce their energy by moving from the bulk into a GB. Resultant interaction between the solute atoms and a GB makes the GB motion more difficult. However the role of the GB segregation effect on AGG has not been clarified. In this study we simulate the 2D and 3D grain growth accompanying boundary segregation of solute atoms by using a phase-field model. It is shown that the segregation plays an important role on the occurrence of AGG. The boundary-segregation-induced AGG can take place when the average driving force of grain growth approaches a critical condition for pinning-depinning transition in solute-drag atmosphere.
Stored Energy Characterization after Low Deformation by Rolling or Tension of an IF-Ti
Authors: Samet-Meziou Amel , Etter Anne Laure , Baudin Thierry , Penelle Richard
Published: March 2009

The stored energy during cold working has been estimated by two approaches. In the first approach, line broadening measurements were determined by neutron diffraction. The second approach is based on the model developed by Dillamore et al. [1]. Therefore, great attention has been paid to the influence of the deformation cell morphology, cell size and the eventual presence of orientation gradient inside the grains according to their orientation. Experimental results show this hierarchy E{111} <112> >E{111} <110>>E{001} <110>.
Recrystallization Behaviour of Cold Rolled Low Carbon Steel Strip with Various Starting Microstructures
Authors: Xu Wan Qiang , Ferry Michael
Published: March 2009

The effect of initial microstructure (acicular ferrite (AF), polygonal ferrite (PF) and strip cast (SC)) on the recrystallization behaviour of low carbon (LC) steel was investigated. Steel strip samples (0.05 wt.% C) of 2 mm in thickness were heat treated to produce an AF and PF microstructure from coarse austenite. The AF, PF and a similar chemistry SC sample manufactured from a twin roll caster were cold rolled to 50, 70 and 90% reduction, and annealed for various times in the temperature range 580-680 °C. The evolution of microstructure during recrystallization was studied by optical microscopy and electron backscatter diffraction (EBSD) in the SEM. The initial microstructure was found to have a substantial influence on the recrystallization behavior. PF recrystallized more rapidly than AF with SC showing extremely sluggish recrystallization behaviour. The recrystallizing grains in these initial microstructures have a lognormal distribution and the recrystallized number density (grains/mm2) decreased during annealing, with the initial microstructures affecting the degree of this decrease in number density.
Investigation of Retained Strains during Multipass Deformation
Authors: Candic Mirza , Tian Bao Hui , Kleber Siegfried , Wießner Manfred , Sommitsch Christof
Published: March 2009

Double-hit compression tests were carried out at different temperatures and strain rates for a nickel
based alloy and a stainless steel. Using microhardness measurements the retained strains after the
first and second pass were investigated as a function of the amount of deformation, temperatures as
well as strain rates and dwell durations. In general, the retained strain decreases with increasing
dwell durations. It is shown that at a given total amount of deformation, the retained strain is
reduced for the as deformed grains that have not been recrystallized yet, but increased for the
recrystallized grains, when comparing double hit with single hit compression tests.
Effect of Warm Deformation on Ferrite Microstructure Evolution in a Ti-Microalloyed Steel
Authors: Eghbali Beitallah
Published: March 2009

Warm deformation is one of the promising hot rolling strategies for producing thin hot rolled steel strips. A better understanding of the microstructure evolution during warm deformation is important for a successful introduction of such processing into the industrial production. In the present research, the effect of deformation strain on the ferrite microstructure development in a low carbon Ti-microalloyed steel was investigated through warm torsion testing. Microstructural analysis with optical microscope and electron back-scattering diffraction was carried out on the warm deformed ferrite microstructures. The results show that at the early stage of deformation an unstable subboundaries network forms and low angle boundaries are introduced in the original grains. Then, with further straining, low angle boundaries transform into high angle boundaries and stable fine equiaxed ferrite grains form. It was considered that dynamic softening and dynamically formation of new fine ferrite grains, with high angle boundaries, were caused by continuous dynamic recrystallization of ferrite.
Determination of the Factors Controlling Crystallography Non-Conformance in Single Crystal Turbine Blade Production on an Industrial Scale
Authors: Cameron J. , Shelton P.W.
Published: March 2009

The arduous conditions to which hot section turbine components are subjected in service, dictate the superior physical and mechanical properties demanded of them. The demand for both high temperature and creep resistance, and anisotropic property requirements of the components has lead to developments in alloy composition, component geometry and single, oriented grain structure design. The slim tolerances and high quality standards imposed on such design features, combined with the high production volume in industry means that component non-conformances to the customer specifications occur. The input variables contributing to crystallography non-conformance in single crystal production have been investigated with a view to defining optimum process parameters for the successful manufacture of single crystal investment cast components on an industrial scale.
Effect of A-Site Ions Additions on Abnormal Grain Growth and Piezoelectric Properties in NKN-5LT Systems
Authors: Kim Min Soo , Jeong Soon Jong , Song Jae Sung
Published: March 2009

Dense 0.95(Na0.5K0.5)NbO3-0.05LiTaO3 (NKN-5LT) ceramics, as a candidate for leadfree piezoelectric materials, were developed by conventional sintering process. The effect of additions with A-site ions in perovskite structure on abnormal grain growth and piezoelectric properties in NKN-5LT ceramics was investigated. Sintering temperature was lowered by adding A-site ions as a sintering aid. Abnormal grain growth in NKN-5LT ceramics was observed with varying additions. This grain growth behavior was explained in terms of interface reactioncontrolled nucleation and growth. The electrical properties of NKN-5LT ceramics were investigated as a function of concentration of additions. The electromechanical coupling factor and piezoelectric constant of NKN-5LT ceramics were improved in the samples with A-site ions excess NKN-5LT. These results show that the piezoelectric properties of NKN-5LT samples can be improved by control of the microstructures.
Reconsideration of the So-Called von Neumann Paradox in the Reflection of a Shock Wave over a Wedge
Authors: Vasilev Eugene I. , Elperin Tov , Ben-Dor Gabi
Published: March 2009

Numerous experimental investigations on the reflection of plane shock waves over
straight wedges indicated that there is a domain, frequently referred to as the weak shock wave
domain, inside which the resulted wave configurations resemble the wave configuration of a Mach
reflection although the classical three-shock theory does not provide an analytical solution. This
paradox is known in the literature as the von Neumann paradox.
While numerically investigating this paradox Colella & Henderson [1] suggested that the
observed reflections were not Mach reflections but another reflection, in which the reflected wave
at the triple point was not a shock wave but a compression wave. They termed them it von Neumann
reflection. Consequently, based on their study there was no paradox since the three-shock theory
never aimed at predicting this wave configuration.
Vasilev & Kraiko [2] who numerically investigated the same phenomenon a decade later
concluded that the wave configuration, inside the questionable domain, includes in addition to the
three shock waves a very tiny Prandtl-Meyer expansion fan centered at the triple point. This wave
configuration, which was first predicted by Guderley [3], was recently observed experimentally by
Skews & Ashworth [4] who named it Guderley reflection.
The entire phenomenon was re-investigated by us analytically. It has been found that there are in
fact three different reflection configurations inside the weak reflection domain:
• A von Neumann reflection – vNR,
• A yet not named reflection – ?R,
• A Guderley reflection – GR.
The transition boundaries between MR, vNR, ?R and GR and their domains have been
determined analytically.
The reported study presents for the first time a full solution of the weak shock wave domain,
which has been puzzling the scientific community for a few decades.
Although the present study has been conducted in a perfect gas, it is believed that the reported
various wave configurations, namely, vNR, ?R and GR, exist also in the reflection of shock waves
in condensed matter.