bluuebunny/crossref_metadata_2025 huggingface dataset:
The Development of Reliability Modeling and Analysis Tool Based on Stochastic Petri Nets
Authors: Wang Wei Ping , Bao Shi Yi , Gao Zeng Liang
Published: June 2010

Given the existing difficulties in conventional reliability models and the limitations of the current SPN software tools in terms of modeling system reliability, a software tool for modeling system reliability based on SPN named RelSPN@zer is developed, describing both the general structure and the underlying numerical methods of the tool. RelSPN@zer provides a unified framework for the modeling and evaluation of SPN running under MATLAB environment and is especially tailed to the system reliability analysis. Many metrics of system reliability can be obtained both under stationary and transient state. An example is given to illustrate the use of this package.
Wear Life Prediction Model on 38CrMoAlA Alloy Steel
Authors: Yan Yu Tao , Sun Zhi Li , Zhang Feng He
Published: June 2010

The wear experimental project on load and sliding speed was instituted by the uniform design method, the wear properties of 38CrMoAlA alloy steel under dry friction were investigated on a vertical universal friction and wear tester, the worn surfaces of specimens were observed by scanning electron microscope (SEM). The wear life predication model of 38CrMoAlA alloy steel was established by multiple regression analysis, and the significance of influencing factors was carried out. The results showed that the distribution of experimental points chosen by uniform design method was in research range, and the experimental efficiency was evidently increased, and the experimental cycle was shortened. The wear mechanism of 38CrMoAlA alloy steel was primarily abrasive wear and adhesive wear. It is found that the wear life predication model was highly significant.
Heterogeneous Knowledge Integrated Management Based on Topic Maps in Collaborative Product Development
Authors: Yan Li Yun , Li Zong Bin , Yang Xiao Chun
Published: June 2010

. Successful collaborative product development depends on the ability to effectively manage and share engineering knowledge and experience throughout the entire development process. This paper presents a distributed heterogeneous engineering knowledge management approach for the practice of collaborative product design. Firstly, a XTM based heterogeneous knowledge integration model in collaborative product design is proposed; Then, a knowledge management framework in collaborative design process is developed; Finally, a knowledge management system in collaborative design is constructed.
Finite Element Analysis on the Ability of Solder Joints to Resist Thermal Fatigue
Authors: Yang Xue Xia , Zhang Yu , Shu Xue Feng
Published: June 2010

The purpose of this paper is to study the ability of solder joints to resist thermal fatigue. 2D simplified models of Plastic Ball Grid Array package (PBGA) structures with ten different solder joints obtained from surface mount experiment are established by finite element software, then stress-strain response of solder joints subjected to the thermal cycle load are calculated. And the effects of shape parameters of solder joints on the ability to resist thermal fatigue are discussed. Results indicate that for the same material and volume solders, the solder joints which have higher height, smaller diameter and contact angle have a stronger ability against thermal fatigue, and that the thermal fatigue characteristics are also greatly influenced by the solder outlines. Comparing with SP solder joints, LF solder joints have stronger ability against thermal fatigue.
Damage Modes and Strength Reliability Strategies of Railway Wheel Set
Authors: Zhao Yong Xiang , Zhang Bin
Published: June 2010

Damage modes, causes, and effects of railway wheel set are investigated from wide production fields. And then, the reliability strategies are classified as service reliability and development reliability. The development one includes design, material and manufacturing, quality approval/authentication, which is a basis of the service one. The service one is the true product quality, which has not only the basis of development reliability but also the effects of non-destructive monitoring level, damage analysis and assessment capacity, and repairing and renewing policies. Reliability of wheel set is so important that a series of code-based regularities have been issued by professional societies or associations. Optimal design is a most effective way to improve wheel set reliability. And in service, non-destructive inspection and repair opportunities are valuable to be synthetically programmed. The critical damage defect/flaw sizes should be scientifically determined. Three advances in strength reliability field should be introduced. They are affordable and appropriate method for reliability assessment and fatigue life prediction including the super long life regime, no-Paris type crack growth models which include crack initiation, stable growth, and approach fracture, and fatigue S-N relation derived from short cracking growth behaviour.
Visualized Analysis and Simulation Research on Dynamic Performance of the Whole NC Machine Tool
Authors: Wang Bo , Sun Wei , Chen Yan , Tang Le , Wen Bang Chun
Published: June 2010

The dynamic performance of numerical control (NC) machine is not only basis of evaluation for the vibration resistance and stability, but also theory basis of optimizing dynamic performance, and improving processed quality. As digital design method, visual design realizes "visibility" during the whole design process, increases design efficiency and guarantees the quality, which make visual design preferred design method in large mechanical engineering. In this paper, the analysis of dynamic performance on NC machine and visual design method will be integrated, taking a NC machining center built by Shenyang machine tool group as a study case, the dynamic visual design flow to be proposed, including the design purpose, content and design methods, finally, the dynamic performance of visual simulation we have done, taking the strength, inherent characteristics and harmonic response into account, offers the foundation about structural performance optimization on the machine.
Mean Square Error Criteria to Multiple Quality Characteristics Robust Design by the Weighted Tchebycheff Method
Authors: Shen Li Juan , Zhao Yu , Yang Jun
Published: June 2010

Robust design has been widely applied in quality improvement. For most products, quality is multidimensional. Little attention has been paid to multiple quality characteristics robust design (MQCRD). MQCRD mainly faces two problems: measurement model and multiple objectives optimization. In order to give an appropriate measurement criterion and generate better Pareto solutions, a MQCRD model by the Weighted Tchebycheff method based on the mean square error (MSE) criterion is proposed. Firstly the MSE estimations for each quality characteristic are obtained by response surface method (RSM) and a MQCRD model based on the MSE criteria is given. Then a MQCRD model by the Weighted Tchebycheff method is present, which minimizes the distance between objective functions and the idea point based on the weighted infinite norm. The proposed approach could find very efficient Pareto solutions. Illustrative example shows the model can generate more efficient and robust solutions than the weighted-sum approach. Furthermore it has better results than the generalized reduced gradient (GRG) and quadratic loss function approach.
Analysis of Dynamic Behavior of a Large-Sized Vibration Fluidized Bed
Authors: Kong Xiang Wei , Kang Xiao Hui , Li Bin , Song Zhao Feng
Published: June 2010

Using the traditional vibration theory and fluid dynamics, the dynamic parameters satisfying the requirements of the 150t/h large-sized vibration fluidized bed were calculated, and the dynamic behavior of the bed was simulated with the ADAMS software. The parameters were optimized according to design requirements and a feasible model and valuable parameters were achieved.
An Improved Ant Colony Optimization for the Vehicle Routing Problem in Logistics Distribution
Authors: Qi Cheng Ming
Published: June 2010

The routing of a fleet of vehicles to service a set of customers is important in logistic distribution systems. The main objective of Vehicle routing problem (VRP) is to minimize the total required fleet size for serving all customers. Secondary objectives are to minimize the total distance traveled or to minimize the total route duration of all vehicles. In this paper, we present a hybrid ant colony System, named PACS, coupled with a pareto local search (PLS) algorithm and apply to the VRP and its variant, the VRP with Time Windows (VRPTW). The algorithm only chooses partial customers randomly to compute the transition probability and PLS can help to escape local optimum. Experiments on various aspects of the algorithm and computational results for some benchmark problems are reported. We compare our approach with some classic, powerful meta-heuristics and show that the proposed approach can obtain the better quality of the solutions.
The Judgement for Generalized Positive Definite Matrices in Signal Processing
Authors: Liu Xue Ting
Published: June 2010

The generalized positive definite matrix is an active research field of special matrix, they have applied in computational mathematics, economics, physics, biology, applied mathematics, numerical computation, signal processing, coding theory, oil investigation in recent years, and so on. In this paper, motivated by [3], we give a simple and convenient judging methodwhich can be used to judge whether an nonnegative real matrix A is an generalized positive definite matrix or not.
Real-Time Simulation of Tissue Cutting with CUDA Based on GPGPU
Authors: Yuan Zhi Yong , Ding Yi Hua , Zhang Yuan Yuan , Zhao Jian Hui
Published: June 2010

A novel approach to simulate soft tissue cutting in a virtual reality endoscopic simulator for surgical training is proposed in this paper. This approach is based on both the improved mass-spring model and the use of computational geometry. A virtual spring is introduced and harnessed to help compensate the shortcoming of the conventional mass-spring model, and a detection algorithm utilizing decomposition of affine coordinates is adopted for the purpose of determining the springs that intersect with the cutting plane. To speed up the simulation performance, algorithms and data structures for the cutting model are designed and implemented based on GPGPU (General-purpose computing on graphics processing units). The performance comparison on the GPU and CPU demonstrates that the proposed method is efficacious and practical.
A New Artificial Immune Algorithm for Flexible Job-Shop Scheduling
Authors: Hong Lu
Published: June 2010

Flexible job-sop scheduling problem (FJSP) is based on the classical job-shop scheduling problem (JSP). however, it is even harder than JSP because of the addition of machine selection process in FJSP. An improved artificial immune algorithm, which combines the stretching technique and clonal selection algorithm is proposed to solve the FJSP. The algorithm can keep workload balance among the machines, improve the quality of the initial population and accelerate the speed of the algorithm’s convergence. The details of implementation for the multi-objective FJSP and the corresponding computational experiments are reported. The results indicate that the proposed algorithm is an efficient approach for the multi-objective FJSP.
Decision Making Based on Rough Set Theory and Weight Value
Authors: Xu E , Shao Liang Shan , Yang Fang , Qu Tao , Gu Xin Cai
Published: June 2010

In this paper, we present a solution developed at rough set theory and weight value to make multiattribute decision with incomplete information. The paper defined the concepst of breaking points and recovered the incomplete information system according to the relationship between the condition attributes and decision attributes. And introduced OWGA(ordered weight geometric averaging) operators to calculate the aggregation value of each project. Finally, selected the project with the maximum aggregation value as the best decision making. The illustration and experiments were implemented and the results indicate that the method is effective and efficient.
Research on the Application of Improved Association Rule Algorithm in Supply Chain Management
Authors: Jiang Fang , Zhao Jie , Ge Han Lin
Published: June 2010

Effective Supply Chain Management (SCM) approach must focus on flexible supply and production processes as well as rapidly respond to change of customer demands. To make up of existing drawbacks of association rule data mining algorithm, the paper brought out an improved algorithm and applies it in the product relativity analysis of SCM. Based on the algorithm, the solution of how the parts be arranged can achieve more cost-effective and higher profits can be achieved by data mining. The mining result can not only guide customers to correctly shopping, but also help manufacturers to design and produce goods, so that the companies can be in a better competitive position.
The Novel Routing Algorithms Based on ACO and GAs
Authors: Zhang Rong Hu , Zhou Shu
Published: June 2010

The paper proposed a novel methods in order to solve the congestion and routing
oscillation, which based on crossover and mutation of the ant colony algorithm to achieve dynamic
QoS routing realization. The algorithm expanded the scope of the search path selection adaptively
adjust the strategy and the amount of information to determine the probability of renewal strategy,
which can better adapt to dynamic network environment, you can make the shortest possible path of
choice to meet the real-time applications, while avoiding link load is heavy, maintaining the
distribution of network load balance. The simulation results show that the routing algorithm has better
convergence speed and stability, which can more effectively address congestion and routing
oscillation, its performance compared with traditional methods have been noticeably elevated,
indicating it has a better multimedia network environment flexibility.
Forecasting Groundwater Level Based on Relevance Vector Machine
Authors: Wang Li Ying , Zhao Wei Guo
Published: June 2010

Relevance Vector Machine (RVM) is a novel kernel method based on sparse Bayesian, which has many advantages such as its kernel functions without the restriction of Mercer’s conditions, and the relevance vectors are automatically determined and have fewer parameters. In this paper, the RVM model is applied to forecasting groundwater level. The experimental results show the final RVM model achieved is sparser, the prediction precision is higher and the prediction values are in better agreement with the real values. It can be concluded that this technique can be seen as a very promising option to solve nonlinear problems such as forecasting groundwater level.
Parameters Optimization in SVM Based-On Ant Colony Optimization Algorithm
Authors: Liu Xiang Ying , Jiang Hui Yan , Tang Feng Zhen
Published: June 2010

In this paper ACO (Ant Colony Optimization) algorithm, which is a well-known intelligent optimization method, is applied to selecting parameters for SVM.ACO has the characteristics of positive feedback, parallel mechanism and distributed computation. This paper gives comparison of ACO-SVM, PSO-SVM whose parameters are determined by particle swarm optimization algorithm, and traditional SVM whose parameters are decided through trial and error. The experimental results on real-world datasets show that this proposed method avoids randomness and subjectivity in the traditional SVM. Additionally it is able to gain better parameters which could dedicate to a higher classification accuracy than the PSO-SVM. Results confirm that proposed optimization method is better than the two others.
A Negative Selection Algorithm Based on Hierarchical Clustering of Self Set
Authors: Chen Wen , Li Tao , Liu Xiao Jie , Shi Yuan Quan
Published: June 2010

In this article, we proposed a negative selection algorithm which based on hierarchical level cluster of self dataset CB-RNSA. First the self data set is clustered by different cluster radius, and then the self data are substituted by cluster centers to compare with candidate detectors to reduce the number of distance counting. In the detector creating process, the value of each detector property was restricted to a given value range so as to decrease the redundancy of detectors. The stimulation result shows that CB-RNSA is an effective algorithm for the creation of artificial immune detectors.
Using Cumulative Histogram Maps in an Adaptive Color-Based Particle Filter for Real-Time Object Tracking
Authors: Zhao San Lung , Wang Shen Zheng , Lee Hsi Jian , Pai Hung I
Published: June 2010

The study presents a human tracking system. To tracking a person, we adopt a particle filter as tracking kernel, since the method has proven successful for tracking in non-linear and non-Gaussian estimation. In a particle filter, a set of weighted particles represents the possible target sates. In this study, we measure the weight according to both the appearances of the target object and background scene to improve the discriminability between them. In our tracker, the appearances are modeled as color histogram, since it is scale and rotation invariant. However, the color histogram extraction for a large number of overlap regions is repeated redundantly and inefficiently. To speed up it, we reduce the cost for calculating overlapped regions by creating a cumulative histogram map for the processing image. The experimental results show that the tracker has the best precision improvement, and the tracking speed is 49.7 fps for 384 × 288 resolution, when we use 600 particles. The results show that the proposed method can be applied to a real-time human tracking system with high precision.
The Study on Protection Algorithms in Multi-Domain Optical Networks
Authors: Li Xue Yong , Gao Guo Hong , Miao Guo Yi , Yan Shi Tao
Published: June 2010

This paper proposes two protection algorithms SBP and PBP with the waveband grouping in fault-tolerant multi-domain optical networks. We also present the concept of layered auxiliary graph to achieve the multi-domain waveband grouping. Simulation results show that PBP performed better than SBP.
The Safety Control of Computer Systems and Networks Based on Adaptive Approach
Authors: Li Xue Yong , Fu Jun Hui , Gao Guo Hong , Li Shi Yong
Published: June 2010

The safety control tools in CSN perform supervision and analysis of the parameters of security systems, so these tools are an important part of the security system. The crucial problem is to develop effective methods and tools for the adaptive control of CSN safety. The suggested adaptive safety control module for CSN based on the safety monitoring tools provides the flexible, correct and effective reaction of security system to the intruder actions. This module allows dynamical evaluation of the information value of each CSN resource and setting the optimal parameters of security system. As a result, the suggested tools allow decrease of the possible damage to the CSN resource from successful intrusions, along with decreasing of security system implementation cost.
The 2 High Horizontal Man Sportsman Run-Up Final Step Sport Credits of Long Jump of Horizontal Speed Loss Reason
Authors: Lou Hang Ying , Wang Guo Zheng
Published: June 2010

This paper compared relevant kinematic parameters of the long jump elites from home and abroad, it analysed the reason why the reduction of the horizontal velocity in the last two steps in the world elites was 0.48m/s, while 0.68m/s in the domestic elites.The first reason the paper presented is to jump up too early which leads to the decrease of the velocity in the last two steps, the second reason is that the accelerative ability is weak and the length of one step varies, and the third reason is that the landing angle of the last step is small but it is big for the angle of departure. Apart from the above mentioned reasons, the paper also proposed another indispensible factor is that, the change of the knee angle in the last two steps which can help prevent the horizontal velocity from deceasing.
Study on HSE Management of Our Construction Enterprise
Authors: Ming Li
Published: June 2010

HSE is a system management methodology of reducing and eliminating the possible risks of health, safety and environment in the process of production. This paper analyzed the feature of HSE management system, and discussed on the feasibility and the role of HSE management system applied to construction projects for construction enterprise. Then China’s enterprise status of HSE management was analyzed, the problem for China’s enterprise to implement HSE management system was described, and the development direction for China’s construction enterprise to implement HSE management system was put forward at last.
The Transient Stability Preventive Control of Power System Based on RBF Neural Network
Authors: Yu Lan Lan , Tan Bo Xue , Meng Tian Xing
Published: June 2010

The transient stability preventive estimation and control is one of the most important tasks of the power system. The traditional time domain simulation method cannot meet the standard of on-line estimation because of its heavy computation burden. In this paper, we realize the on-line estimation of transient stability limits on critical lines of a power system using the favorable approximation ability of RBF network. We choose right samples by off-line count to train the RBF network in order to make the error satisfy demand. Preventive control direction and amount are determined based on first-order sensitivities of transient stability limits to generator outputs. The sensitivities are derived from partial derivatives of RBF network outputs to inputs. In the end, we take a practical power system for an example to demonstrate the efficiency of RBF network in estimation of the transient stability limit on critical lines and ability to provide preventive control strategy.
Synthesizing Pattern with Broad Nulls through Orthogonal Method
Authors: Huang Long Yang , Pan Wei Jun
Published: June 2010

Based on the Gram-Schmidt orthogonalization method utilized for pattern synthesis of linear array without constraints, null derivative constraints are proposed to implement pattern synthesis with broad nulls. The advantage of the simplified computation resulted from steering vector orthogonalization in unconstrained orthogonal approach is maintained, and the uniform or non-uniform linear array pattern synthesis can be realized by this method. The experimental results show that the null constrained orthogonal approach can fulfill linear array pattern synthesis with constrains such as null constrains, first-order and second-order derivative null constraints.
Study of Optimum Conditions for Zinc Plating on Mild Steel
Authors: Amuda Muhammed Olawale Hakeem , Subair W. , Obitayo O.W.
Published: June 2010

The effect of some process parameters on the weight of zinc deposited on mild steel in a typical electroplating process is reported. The study indicates that the weight of zinc deposited on mild steel during the process is affected by plating temperature, current density, plating bath pH and plating time. The study established that optimum deposition of zinc is achieved at plating temperature of 320C, plating bath pH of 4.4, current density 40mA/cm2 and plating time of 30 minutes. 8.7mg of zinc was deposited at optimum deposition conditions. The profile of the zinc deposited decreases after optimum deposition is attained.
Dynamic Deformation of Submicrocrystalline Aluminum Alloys
Authors: Ko Young Gun , Kim Y.G. , Namgung S. , Shin Dong Hyuk , Lee Sung Hak
Published: June 2010

In this study, dynamic deformation behavior of submicrocrystalline aluminum alloy was established with respect to equal-channel angular (ECA) pressing routes such as A, B, and C. After 8-pass ECA pressings, the deformed samples, regardless of the routes applied, were consisted of ultrafine grains together with high dislocation density near the boundaries. Microstructural observation revealed that the sample deformed via route B showed more diffused diffraction pattern than those deformed via route A and C, suggesting the fact that route B was most effective for a rapid evolution in the grain boundary orientation from low-angle to high-angle characteristics. In the torsion tests, the shear stress decreased once reaching the maximum point. This maximum was the highest in the sample deformed via route B, and decreased in the order of the route C and route A. The dynamic deformation was explained based on microstructural uniformity associated with ECA pressing routes.
Texture Distribution through Thickness in 6xxx Aluminum Alloy Sheet Fabricated by Cross-Roll Rolling Method
Authors: Lee Kwang Jin , Jeon Jae Yeol , Woo Kee Do
Published: June 2010

Texture distribution through thickness in 6xxx aluminum alloy cross-roll rolled sheet has been investigated using the electron back-scattered diffraction (EBSD) technique. Analyses of texture in three layers from the surface to the center of the sheet were performed. Near the surface, shear type textures including {012}<142> orientation and {112}<110> orientation were found and β-fiber texture were dominating. In the center layer, very weak β-fiber texture {112}<111> orientation, {123}<634> and {011}<211> were found with Cube, Cube-ND and Goss orientation plus others.
Assessing of Bendability of Aluminum Alloy Sheets for Autobodies
Authors: Masuda Kazuhiro , Itoh Goroh , Itoh Nobuhide
Published: June 2010

In recent years, reducing carbon dioxide is being demanded in terms of preventing global warming. Lightening autobodies is one of the most practical ways to conduct it, for which converting the body sheets from conventional steel to Al-Mg-Si alloy is effective. Although the Al-Mg-Si alloys have the advantage that they have hardenability during paint baking and do not cause stretcher strain patterns, poor formability is a crucial drawback. Bendability is one of the most important properties related to formability. However, there has been no assessing method having both speediness and quantitative reproducibility. In this study, we have developed a assessing method based on the electric resistance decrease arising from the decrease in conducting section when cracks are formed by bending. Bendability was assessed by electrical resistance change as well as by crack density on the tension surface measured with an SEM. It was found that the new method have far greater speediness with the same quantitative reproducibility than the crack measurement method.
High Glass-Forming Ability and Unusual Deformation Behavior of New Zr-Cu-Fe-Al Bulk Metallic Glasses
Authors: Zhang Qing Sheng , Zhang Wei , Louzguine-Luzgin Dmitri V. , Inoue Akihisa
Published: June 2010

A new series of bulk metallic glasses were developed by addition of Fe into the ternary Zr60Cu30Al10 alloy. Although Fe-Cu element pair shows distinct immiscibility with a large positive heat of mixing, substitution of Fe for Cu significantly improves the glass-forming ability of the ternary Zr60Cu30Al10 alloy. The critical diameter for glass-formation increases from 8 mm for Zr60Cu30Al10 alloy to 20 mm for Zr60Cu25Fe5Al10 and Zr62.5Cu22.5Fe5Al10 alloys. As compared with the ternary Zr60Cu30Al10 alloy, the new quaternary Zr-Cu-Fe-Al alloys show lower liquidus temperatures. The Zr60Cu25Fe5Al10 and Zr62.5Cu22.5Fe5Al10 alloys, the best BMG-formers in this alloy system, are found to locate very near a Zr-Cu-Fe-Al eutectic point. The new Zr-Fe-Cu-Al bulk metallic glasses exhibit high strength of about 1700 MPa. The plastic strain increases from 7.8% to 11.3% with increasing the content of Fe from 0 to 12.5%. The finding of a Ni-free Zr-based bulk glassy alloy with the extremely high glass-forming ability is expected to extend the future application of bulk metallic glasses.
Bulk Metallic Glass Formation, Crystallization, and Magnetic Properties of RE4Fe72B22M2 Alloys
Authors: Cui Xue Hong , Liu Zhong Wu , Zeng De Chang
Published: June 2010

The RE4Fe72B22M2 (RE=Y, Dy or Nd; M=Nb or Ta) alloys in ribbon and rod forms were prepared by melt spinning and water cooling copper mold casting methods, respectively. Amorphous structure was observed in all ribbon samples, but the results from rod samples indicated that the composition has an important effect on the glass formability. All rod samples with RE=Y or Nd were partly amorphous, while bulk metallic glass (BMG) rod with a diameter of 2 mm was obtained for the Dy4Fe72B22Nb2 alloy. The rare earth and doping elements on the glass formability have been discussed. The effects of post-annealing on the microstructure and magnetic properties of these alloys have been investigated. The results presented here provide a viable method to get fully dense bulk hard magnets.
Characteristics of Ti-Ni-Zr Thin Film Metallic Glasses Exhibiting a Shape Memory Effect after Crystallization
Authors: Sakurai Junpei , Aono Yuko , Ishida Yui , Hata Seiichi
Published: June 2010

We investigated characteristics of Ti-Ni-Zr amorphous thin films before and after annealing, in order to search for novel Ti-Ni-Zr thin film metallic glasses (TFMGs) that exhibit a shape memory effect after crystallization. We found that the Ti42Ni47Zr11 TFMG exhibited a stable shape memory effect after crystallization. This alloy showed a glass transition with the glass transition and crystallization temperatures of 703 and 760 K, respectively. Moreover, this alloy showed a one-step martensitic phase transformation of B2 to B19', when annealed at 973 K for 3.6 ks. The martensitic phase start temperature and reverse martensitic phase start temperature were 296 and 352 K, respectively. In addition, this alloy showed a recovery strain of about 2.4%.
Consolidation Behavior of Cu-Zr-Al Metallic Glass Powder by Spark Plasma Sintering
Authors: Xie Guo Qiang , Louzguine-Luzgin Dmitri V. , Fukuhara Mikio , Kimura Hisamichi , Inoue Akihisa
Published: June 2010

We investigated consolidation behavior of gas-atomized Cu50Zr45Al5 metallic glassy alloy powders by a spark plasma sintering (SPS) process. Density of the sintered samples increased with an increase in sintering temperature. The nearly full density samples without crystallization could be attained by the SPS process at sintering temperature of 693 K under pressure of 600 MPa. The produced samples exhibited high-strength and met large-size requirement. The SPS process makes it possible to fabricate the large-size bulk metallic glasses without limitation of dimensions and alloy system.
Formation of Amorphous Fe-Cr-P-C Alloy Coating Films by a Newly Developed Thermal Spraying Technique
Authors: Komaki Masahiro , Mimura Tsunehiro , Kusumoto Yuji , Kurahasi Ryurou , Kouzaki Masahisa , Yamasaki Tohru
Published: June 2010

Some amorphous Fe-Cr-P-C coating films having high hardness and high corrosion resistance have been produced by a newly developed thermal spraying technique. In order to control the temperatures of the powder particles in the flame spray and the substrate, a newly developed cylindrical nozzle, with external cooling nitrogen gas, was mounted to the front end of the thermal spray gun. Fe70Cr10P13C7 films with various external cooling gas velocities between 20 m/s and 40 m/s exhibited entire amorphous structure without oxides and/or unmelted particles. Corrosion-resistance of the films was observed in immersion tests using various corrosive liquids.
Mechanical and Physical Properties of Nano-Metals
Authors: Lewandowska Małgorzata , Zagórski Andrzej , Kurzydlowski Krzysztof Jan
Published: June 2010

In the present work, an extensive research program has been undertaken to characterise a wide spectrum of properties of nano-metals. In particular, the effect of grain refinement on such properties as fatigue, corrosion and wear resistance, conductivity and thermal stability has been studied for various nano-metals (aluminium, copper and iron alloys). The results have revealed that nano-grain refinement also improves physical properties of single phase metals. A disadvantageous effect of large (micron sized) particles, which do not undergo refinement during the processing, has been also recognized.
New Crystallographic Textures of Nd2Fe14B/α-Fe Nanocomposite Materials Prepared by Controlled Melt Spinning
Authors: Zeng Xie Rong , Sheng Hong Chao , Zou Ji Zhao , Xie Sheng Hui
Published: June 2010

In Nd9.5Fe84B6.5 melt-spun ribbon, the quenching temperature is found to be effective for the texture development of Nd2Fe14B nanocrystals. For a relatively low quenching temperature of 1250°C a (00l) texture of Nd2Fe14B crystals was found on the free-side surface of the ribbons. At a higher quenching temperature of 1350°C, the microstructure of the free-side surface of the ribbons switches into (320) and (517) texture. It is believed that the transformation of the melt at higher temperature triggers the switch of the texture.
Microstructure and Texture Evolution during Friction Stir Processing of AZ31 Mg Alloy
Authors: Xin Ren Long , Li Bo , Liu Qing
Published: June 2010

In this study, a well-textured AZ31 Mg alloy sheet was friction stir (FS) processed, and the microstructure and texture evolution in various regions of the processed alloy were examined by optical microscopy (OM) and electron back scatter diffraction (EBSD). The results showed that the grain size in the FS zone was significantly refined compared to that in the base material (BM). The average grain size in the thermomechanically affected zone (TMAZ) and heat-affected zone (HAZ) was comparable with that in the BM. There is a gradual change of local texture from BM to FS zone due to plastic flow together with heating input during the FS processing. The <0002> direction was roughly parallel to the cylindrical pin surface normal of the FS zone. The <0002> direction in the HAZ is similar to that in the BM, but more diffuse. The <0002> direction in the TMAZ was tilted 25~30o away from the ND and there is a distinct boundary between the FS zone and TMAZ at the advancing side which introduced an incompatibility between the FS zone and TMAZ. This might explain the fact that the transverse FS processed Mg alloys commonly fracture at the advancing side during tensile tests.
Nanostructure Formation during Deep Wire-Drawing of Copper
Authors: Tsuji Nobuhiro , Hanazaki Kenichi
Published: June 2010

It was confirmed in the present study that deep drawing process in multi passes to produce fine wires of copper alloys can act as a kind of severe plastic deformation process. High purity copper was deeply wire-drawn up to an equivalent strain of 6.9, and microstructure evolution and change in mechanical properties were investigated. It was confirmed that deep wire-drawing process produced nanostructures composed of fiber-shaped ultrafine grains with a diameter of about 300 nm. The copper wires having nanostructures showed tensile strength of 480MPa, which was two times higher than that of the starting material. The microstructures and mechanical properties of the deep drawn copper wire were almost equivalent with those of the copper sheets severely deformed by ARB process, though there were some minor differences between two processes.
Effects of Phase Transformation Temperature on Formation of Wear-Induced Layer in Fe-Ni Alloys
Authors: Sato Hisashi , Kubota Yuichi , Miura-Fujiwara Eri , Watanabe Yoshimi
Published: June 2010

Effects of the transformation temperature on formation behavior of the wear-induced layer in Fe alloys are investigated using Fe-33mass%Ni and Fe-30mass%Ni alloys. Martensitic transformation temperature (Ms)　and reverse transformation temperature (As) of Fe-33mass%Ni alloy are lower than those of Fe-30mass%Ni alloy. Microstructure of the wear-induced layer in Fe-33mass%Ni alloy was single austenite phase (γ) with fine grain. On the other hand, the wear-induced layer in Fe-30mass%Ni alloy consists of martensite (α’) and γ with fine structure. This difference is due to the difference of As between these Fe-Ni alloys. Moreover, the microstructure of the wear-induced layer has no dependence on the distribution of α’ in initial microstructure. From obtained results, it is concluded that the formation of the wear-induced layer in Fe alloys is mainly affected by As.
Visualization and Quantification of Severe Internal Deformation on Compressive Torsion Process
Authors: Kume Yuji , Motohashi Masakazu , Kobashi Makoto , Kanetake Naoyuki
Published: June 2010

Compressive torsion process (CTP) which was developed by authors is effective process for grain and precipitates refinement of metallic materials with a severe plastic deformation. In the CTP, a cylindrical specimen is subjected to simultaneous compressive and torsional loading without change in its shape. However, metal flow and strain distribution in the processed specimen are not cleared, because the deformation is very large and complicated. In the present work, visualization of internal deformation of specimen processed by CTP was investigated using dual alloy etching technique. Two kinds of aluminum alloy were prepared by cutting on fan-like shape and alternately placed to a cylindrical shape. After CTPing, contrasts in the specimen were observed by polishing and etching. The internal distribution of shear strain was quantified by measuring the displacement of interface between the alloys. As a result, the visualization and quantification of internal deformation was successfully carried out using the technique. The internal strain distribution was varied not only in radial direction but also in longitudinal direction because of frictional constraint on the lateral face. A laminate contrast of the alloys observed on the vertical cross section was well related with the strain distribution in the specimen.
Effect of Si Content on Fracture Behaviour Change by Strain Rate in Si Steels
Authors: Mizuguchi Takashi , Oouchi Ryota , Ueji Rintaro , Tanaka Yasuhiro , Shinagawa Kazunari
Published: June 2010

Fracture behaviour transitions due to change in the strain rate in steels with various Si content ranging from 2% to 5 wt% were studied. Room-temperature tensile tests were conducted over wide range of strain rates ranging from 10-3 s-1 to 103 s-1. Concerning of the steels with low Si content (no more than 3%), the nominal stress - nominal strain curves represented both uniform and local elongations at all strain rates. On the other hand, in 4% Si steel at a strain rate higher than 101 s-1, the tensile sample broke down without local elongation (necking). The stress at breaking was found to be nearly equal to its work hardening rate. The strain rate at which fracture behaviour transition took place in 5% Si steel (10-1s-1) was lower than that in 4% Si steel. TEM observations clarified the existence of deformation twins in the sample that fractured without necking. These results indicated that Si addition is subject to the brittle fractures and that the fracture mechanism transition is closely related with the deformation twinning behaviour.
Formability of Pure Titanium Long-Cup by Multi-Stage Deep Drawing
Authors: Harada Yasunori , Araki Toshiyuki , Tsuda Takahiro
Published: June 2010

The pure titanium long-cups were formed by preventing the seizing in cold multi-stage deep drawing processes. For the prevention, pure titanium sheets were treated by heating oxide coating. The coating is very effective in preventing the occurrence of seizure and galling. The fresh and clean titanium is not in direct contact with the die during the forming due to the existence of the oxide layer. In multi-stage deep drawing, pure titanium sheets of the JIS grade 2 was employed. Various cups were drawn by exchanging the punch and ringed die. The die was flat in the first stage, and was taped without a blankholder in the subsequent stages. The effects of the coating conditions on the occurrence of seizure in multi-stage deep drawing were examined. It was found that the coating titanium sheet has sufficient ability in preventing the seizure in multi-stage deep drawing processes. The pure titanium long-cups were successfully formed by a multi-stage deep drawing operation in cold.
Study on Powder Metallurgical Preparation of NiCoMnIn Alloy Foam
Authors: Wang Gang , Xiong Xiao Ming , Liu Yan Dong , Wang Chun Yan , Wang Yan Dong , Zuo Liang
Published: June 2010

The magnetic shape-memory alloy NiCoMnIn shows, in monocrystalline form, a large reversible magnetic-field-induced strain (MFIS). But it is difficult to achieve the properties in polycrystalline NiCoMnIn alloys. The technique of powder metallurgical preparation of NiCoMnIn foam was studied to improve the properties of polycrystalline NiCoMnIn alloys in the present paper. We introduced a processing route including choosing appropriate space-holding fillers, sintering NiCoMnIn alloy and the filling agent with appropriate grain size. The sintering temperature and time and the optimum volume fraction of the filling agent were determined by analysis of the structure of sintered bulk foams.
Non-Equilibrium Solidification in Cu-Mg-Sn Alloys for Tribological Applications
Authors: Bravo Agustín , Schouwenaars Rafael , Jacobo Víctor H. , Ortiz Armando
Published: June 2010

Mg-containing bronzes have received little attention in general technological applications due to their relatively complex processing conditions. However, Mg is one of the few metallic elements which may exhibit good tribological compatibility with iron and steel and as such is a possible candidate to replace lead in sliding bearing materials. This work describes the casting of such alloys in the form of thin ingots to produce cold rolled strip, as is done for commercial Al-Sn-based ductile triboalloys. Sound ingots could be produced with simple laboratory equipment, yielding slabs in the compositional range of Cu1Mg1Sn, Cu1Mg5Sn, Cu5Mg1Sn and Cu5Mg5Sn. Cooling curves were monitored by embedded thermocouples. Invariant points could be identified after appropriate filtering of the signal but did not correspond to the ternary equilibrium. Segregation and non-equilibrium phases were confirmed by metallography.
Effect of Various Processing Route on Microstructure and Mechanical Properties of Spray-Deposited Al-8.6Zn-2.6Mg-2.2Cu Alloy
Authors: Wang Feng , Xiong Bai Qing , Zhang Yong An , Zhu Bao Hong , Liu Hong Wei , Li Zhi Hui , Li Xi Wu
Published: June 2010

Spray deposition is a novel process which is used to manufacture rapidly solidified bulk and near-net-shape preforms. In this paper, Al-8.6Zn-2.6Mg-2.2Cu alloy was synthesized by the spray atomization and deposition technique. The microstructural development during subsequent hot extrusion, hot rolling and canned forging was investigated by means of scanning electron microscope and X-ray diffraction. The results indicate that the spray-deposited alloy exhibits a uniform microstructure composed of the Al matrix and Mg(ZnCu)2 compounds with various shape. The fragmentation of the Mg(ZnCu)2 phases in the alloy has been regarded as one of the main phenomena during extrusion, rolling and forging. Under T6 temper condition, the hot-extruded Al-Zn-Mg-Cu alloy displays superior strength, and higher than hot-rolled and canned-forged ones.
Application of a Criterion for Cold Cracking to Casting High Strength Aluminium Alloys
Authors: Lalpoor Mehdi , Eskin Dmitry G. , Fjær Hallvard Gustav , Ten Cate Andreas , Ontijt Nick , Katgerman Laurens
Published: June 2010

Direct chill (DC) casting of high strength 7xxx series aluminum alloys is difficult mainly due to solidification cracking (hot cracks) and solid state cracking (cold cracks). Poor thermal properties along with extreme brittleness in the as-cast condition make DC-casting of such alloys a challenging process. Therefore, a criterion that can predict the catastrophic failure and cold cracking of the ingots would be highly beneficial to the aluminum industry. The already established criteria are dealing with the maximum principal stress component in the ingot and the plane strain fracture toughness (KIc) of the alloy under discussion. In this research work such a criterion was applied to a typical 7xxx series alloy which is highly prone to cold cracking. The mechanical properties, constitutive parameters, as well as the KIc values of the alloy were determined experimentally in the genuine as-cast condition and used as input data for the finite element package ALSIM5. Thermomechanical simulations were run for billets of various diameters and the state of residual thermal stresses was determined. Following the contour maps of the critical crack size gained from the model, the casting conditions were optimized to produce a crack-free billet.
Grain Refinement Performance of Al Cast Using Machining Chips
Authors: Watanabe Yoshimi , Tabushi Kenichi , Sato Hisashi , Miura-Fujiwara Eri
Published: June 2010

In this study, grain refinement performance of as-cast Al using machining chip of Al instead of the grain refiner is investigated. At first, the machining chips of pure Al are placed in metallic mold. Then, pure Al melt is inserted into the mold with the machining chips. From the microstructure of the as-cast Al using the machining chips, it is found that this machining chip in mold can induce grain refinement of as-cast Al. The increment of the Al chips enhances the grain refinement of the as-cast Al. Moreover, it is shown that preheating the mold can reduce the pore inside as-cast Al using the machining chips. This grain-refinement effect by the machining chips would come from the enhancement of cooling rate and the role of the nucleation site. Therefore, it is concluded that the machining chips of Al can enhance the grain refinement of as-cast Al.
Phase Field Simulation of Ni4Ti3 Precipitation in Porous NiTi Shape Memory Alloys under Applied Stresses
Authors: Ke Chang Bo , Ma Xiao , Zhang Xin Ping
Published: June 2010

This study presents the simulation of evolution of Ni4Ti3 variants during stress-assisted aging of NiTi alloys containing nano-scale pores with different sizes, by using phase field approach. The simulation shows that the higher level of applied stress can cause more Ni4Ti3 particles precipitated around pores than that of lower level stress, regardless of pore size; the large pores can “capture” more precipitates while less particles precipitated around the small pores. Moreover, the precipitation of Ni4Ti3 particles exhibits different regional preferences near pores, which means the unixial compressive stress can result in inhomogeneous Ni4Ti3 particle distribution.
Ductile-to-Brittle Transition Behavior of High-Nitrogen 18Cr-10Mn-0.35N Austenitic Steels Containing Ni and Cu
Authors: Hwang Byoung Chul , Lee Tae Ho , Park Seong Jun , Oh Chang Seok , Kim Sung Joon
Published: June 2010

Ductile-to-brittle transition behavior of high-nitrogen 18Cr-10Mn-0.35N austenitic steels containing Ni and Cu was investigated by means of Charpy impact test and fractographic analysis. The commonly observed fracture mode of the specimens tested at -196 oC was transgranular cleavage-like brittle with flat facets occurring along {111} crystallographic planes, thereby leading to the occurrence of ductile-to-brittle transition. For all the steels investigated in the present study, the ductile-to-brittle transition temperature (DBTT) measured from Charpy impact tests was much higher by 90 to 135 oC than that predicted by empirical equation strongly depending on N content. The combined addition of Ni and Cu enabled the 18Cr-10Mn-0.35N steels to have the lowest DBTT, which could be explained by relatively high austenite stability and favorable effect of Cu as well as the absence of delta-ferrite.