bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Oxygen Addition on Isothermal Omega Phase Stability in Ti-29Nb-13Ta-4.6Zr
Authors: Nakai Masaaki , Niinomi Mitsuo , Akahori Toshikazu , Tsutsumi Harumi
Published: June 2010

A peculiar effect of oxygen on ω-phase stability, i.e., the enhancement of the isothermal ω-phase formation during aging due to oxygen addition was observed in the Ti-29Nb-13Ta-4.6Zr; this effect is contradictory to that reported conventionally. The effect was analyzed from the viewpoint of distribution of alloying elements. Oxygen and/or zirconium may dissolve in the ω phase during aging, resulting in the stabilization of the ω phase in this alloy.
Effect of Y2O3 on Mechanical Properties of Ti-29Nb-13Ta-4.6Zr for Biomedical Applications
Authors: Song Xiu , Niinomi Mitsuo , Tsutsumi Harumi , Akahori Toshikazu , Nakai Masaaki , Yonezawa Satoshi , Wang Lei
Published: June 2010

Y2O3 was added to β-type Ti-29Nb-13Ta-4.6Zr (TNTZ) in order to achieve excellent mechanical performance and low Young’s modulus. TNTZ specimens with 0.05%–1.0% Y are all found to be composed of a β phase. Young’s moduli of TNTZ with 0.05–1.0% Y are all maintained low, and are almost the same as that of TNTZ without Y2O3. The grain size of TNTZ with 0.05%–1.0% Y is smaller than that of TNTZ without Y2O3. Moreover, Y2O3 precipitates can prevent the texture movement, and this effect becomes more obvious with an increase in the Y concentration. The tensile strength of TNTZ is successfully improved by adding Y2O3. TNTZ specimens with 0.2% and 1.0% Y exhibit good balance between the tensile strength and the elongation.
Microstructure Characterization of Laser Welded Near-β Titanium Alloy ‘TLM’ under Different Process Conditions
Authors: Buddery Alexander , Wang Gui , Yu Zhen Tao , Dargusch Matthew S. , Nabulsi Samih
Published: June 2010

The microstructures of laser welds of the near-β titanium alloy TLM were studied for substrates in the as hot rolled, solution treated and solution treated and aged conditions. Irrespective of substrate condition the fusion zone consists of a cellular β structure. Trends in bulk hardness of the various conditions seem to be carried through into the weld consistently across the profile. The hardness in the fusion zone remained similar to that of the bulk. However, a drop in hardness occurs in the HAZ. Lath that formed around the hardness indent of the fusion zone and HAZ suggest that the weld undergoes a martensitic transformation to α" during deformation.
Fabrication of Ti-Based Biodegradable Material Composites Prepared by Spark Plasma Sintering Method
Authors: Miura-Fujiwara Eri , Teramoto Takeshi , Sato Hisashi , Kobayashi Equo , Watanabe Yoshimi
Published: June 2010

This study aims at producing porous Ti filled with biodegradable materials for biomedical implants by means of spark plasma sintering method (SPS). To improve bone fixation and to obtain appropriate Young’s modulus as a medical implant material, we applied -tri calcium phosphate (-TCP) to the Ti-based composite. Ti/-TCP powder mixtures were sintered by SPS under applied stress of 45MPa with various temperatures and holding time. Vickers hardness (Hv) of obtained composite increased with increasing the holding time up to 10 min, and saturated hardness was approximately 750 Hv, which is extremely higher than that of bulk Ti. Hardness also increased as sintering temperature increased up to 1473 K. From the results of microstructure observations by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDXS), O- and P- containing Ti surrounded around Ti particle, and O diffused into Ti particle to a certain extent. X-ray diffraction results indicated several kinds of Ti-O and/or Ti-P formed in the specimen. Results indicated that it is the brittle phases formed during sintering that increased the hardness.
Calcium Phosphate Coating on Titanium Using Dry Process
Authors: Narushima Takayuki , Ueda Kyosuke , Goto Takashi , Kurihara Jun , Kawamura Hiroshi
Published: June 2010

Oxyapatite, amorphous calcium phosphate, and double-layered calcium phosphate coating films were fabricated on mirror-polished commercially pure titanium (CP Ti) and blasted Ti-6Al-4V alloy substrates by radiofrequency (RF) magnetron sputtering; the properties of these films were evaluated in vivo and in vitro. The bonding strength between the calcium phosphate films and the Ti substrates was higher than 50 MPa. This value is higher than the bonding strength reported in the case of plasma-sprayed calcium phosphate coating films fabricated on Ti substrates. The removal torque of screw-type blasted Ti-6Al-4V alloy implants in the femurs of Japanese white rabbits increased with the duration of implantation, and the removal torque values of the coated implants was observed to be higher than those of the non-coated implants. In vitro and in vivo studies indicate that coating Ti implants with calcium phosphate films using RF magnetron sputtering is effective in improving the bone compatibility of Ti implants. Finally, the factors that should be considered in fabricating biomedical coating films were discussed.
MAO-Prepared Hydroxyapatite Coating on Ultrafine-Grained Titanium
Authors: Qi Min , Yao Zai Qi , Ivanisenko Yulia , Fecht Hans Jörg
Published: June 2010

The equal channel angular pressing (ECAP) results in ultrafine-grained (~200–500 nm) Ti with superior mechanical properties without the harmful alloying elements, which is beneficial for medical implants. To improve the bioactivity of Ti surface, Ca/P-containing porous titania coating were prepared on the ultrafine-grained Ti and coarse-grained Ti by micro-arc oxidation (MAO) in Ca/P based solution. The phase identification, thickness, composition and morphology of the coatings were analyzed. The amounts of Ca, P and Ca/P ratio of the MAO coating formed on ultrafine-grained Ti were higher than those for coarse-grained Ti samples. Hydroxyapatite and α-Ca3(PO4)2 phases appeared in MAO coating formed on ECAP-treated Ti with increasing reaction time of 20 min (E20). Incubated in simulated body fluid within 2 days, bone-like apatite was completely formed on E20 surface, as evidenced of preferable bioactivity.
Calcium Phosphate Deposition on Magnesium Alloy for Bioimplant Applications
Authors: Kannan M. Bobby , He Ying He , Sandham Andrew
Published: June 2010

Successful application of magnesium-based alloys as biodegradable biomaterials is critically dependent on controlling the degradation rate of the alloy. The present study suggests that electrochemical deposition of calcium phosphate on magnesium alloy at an optimal voltage enhances the degradation resistance of the alloy significantly.
Effect of Cu Content on Unique Hardening Behavior of Dental Ag-Pd-Au-Cu System Alloy Subjected to Solution Treatment
Authors: Kim Yong Hwan , Niinomi Mitsuo , Akahori Toshikazu , Nakai Masaaki , Tsutsumi Harumi , Fukui Hisao
Published: June 2010

Hardness of Ag-20Pd-12Au-14.5Cu (mass%) subjected to a solution treatment (ST) at a temperature over 1073 K followed by water quenching increases drastically. This unique hardening behavior is not clarified becasue of their complex microsturucures. In this study, the relationship between the unique hardening behaviour and the microstructure of dental Ag-20Pd-12Au-xCu subjected to ST with different Cu/Ag ratios was investigated. The Vickers hardness of Ag-20Pd-12Au-14.5Cu increases remarkably from 192 to 286 Hv after ST whereas that of Ag-20Pd-12Au-6.5Cu decreases and that of Ag-20Pd-12Au-20Cu increases slightly after ST, respectively. The spotty regions are observed in only certain areas of Ag-20Pd-12Au-14.5Cu subject to ST. It is considered that the appearance of the spotty regions affects mainly to the unique hardening behaviour in Ag-20Pd-12Au-xCu.
Change in Biological Apatite Orientation in Beagle Mandible
Authors: Fujitani Wataru , Nakano Takayoshi
Published: June 2010

The orientation of biological apatite (BAp) is one of the bone quality parameters dominating bone mechanical function. In the mandible, the preferential orientation of the BAp c-axis changes depending on alteration of the in vivo stress condition induced by a change in the biting stress. In this study, to clarify the functional adaptation of the preferential BAp orientation and bone mineral density (BMD), all beagle mandibular molars on one side were extracted to remove the biting stress, leading to changes in both BAp orientation and BMD. The BMD exhibited discontinuous distribution around the first molar, mainly responsible for mastication, on the normal side. However, the distribution was continuous along the mesiodistal axis of the edentulous side. The preferential BAp orientation was analyzed in mandibular cross-sections at the first molar root region. Molar extraction led to a change in the BAp orientation: immediately under the root region on the lingual sides, two-dimensional preferential alignment in the mesiodistal and biting directions of the normal side changed to one-dimensional alignment along the mesiodistal axis of the edentulous side. One-dimensional alignment was also observed on the buccal sides irrespective of molar extraction. These findings clarify the close relationship between in vivo biting stress and the preferential BAp orientation, and will be useful clinically for diagnosis, implant placement, and so on.
Analysis of Edge Crack of Thin Strip during Cold Rolling
Authors: Xie Hai Bo , Jiang Zheng Yi , Wei Dong Bin , Tieu A. Kiet
Published: June 2010

Cracks in metal product significantly decrease quality and productivity of the rolled thin strip. In this paper the stress intensity factor (SIF) solution of edge crack defect of thin strip during cold rolling was investigated, and a globe analysis was applied to the problem of free edge of thin strip. The effective stress intensity factor range is important because it represents the major physical cause of crack growth. The present study provides insights of the mechanics of edge crack growth that has been frequently observed during thin strip rolling. The efficiency and reliability of the SIF analytical modelling has been demonstrated. The proposed method for predicting edge crack is useful for producing defect-free products in rolling, and provides insights of the mechanism of edge crack growth.
Effect of Penetration Rate on Insertion Force in Trabecular Bone Biopsy
Authors: Mulligan Renae , Yin Ling , Lamont Anthony , Peng Zhong Xiao , Forwood Mark R. , Teoh Swee Hin
Published: June 2010

Bone biopsy is a common procedure in bone disease diagnoses, therapies and research. In this procedure, bone biopsy needles are inserted into bone tissues. Although needle insertion into bone is often essential for the diagnosis of bone diseases, the hard tissue-needle interactions are not quantitatively understood. In this paper, we describe a quantitative assessment of forces involved in insertion of healthy trabecular bone using clinically applied Jamshidi CrownTM bone biopsy needles of gauge 8 (4-mm diameter). The measured forces were related to the insertion depths up to 25 mm and insertion rates of 1 mm/s to 5 mm/s. At the initial insertion stage, a clear linear force-depth relation was measured. With the increase of the insertion depth, the forces increased nonlinearly. In the final stage of insertion, the forces increased much more quickly at the lower insertion rate than that at the higher insertion rate. The maximum insertion force reached approximately 1000 N when the insertion depth reached 25 mm at the insertion rate of 1 mm/s.
Biomimetic Artificial Cortical Bone with Aligned Microstructure Formed by a Combination of Multi-Extrusion and Rolling Processes
Authors: Jang Dong Woo , Sakar Swapan Kumar , Kim Min Sung , Min Yong Ki , Song Ho Yeon , Lee Byong Taek
Published: June 2010

The HAp-(t-ZrO2) ceramic composites with mimetic osteon microstructures were fabricated to investigate the technical feasibility of fabricating natural bone mimetics by a combination of multi-extrusion and rolling processes. The HAp and graphite powders were mixed with ethylene vinyl acetate and stearic acid using a shear mixer, and the mixture was extruded by the multi-extrusion process to create filaments. A HAp sheet was prepared by a rolling process. The HAp filaments and carbon filaments were arranged one by one on the HAp sheet, and the system was rolled to form a mimetic osteon microstructure. Burning out and sintering processes were performed for removal of the organic binder and graphite and for densification. The pore diameter and core of the mimetic osteon microstructure were approximately 50μm and 150μm, respectively. The porosity and bending strength were approximately 60% and 177MPa, respectively in the sample sintered at 1450°C.
Fabrication of Bone Substitutes by the Sponge Replica Method
Authors: Kim Min Sung , Jang Dong Woo , Min Young Ki , Yang Hun Mo , Song Ho Yeon , Lee Byong Taek
Published: June 2010

Calcium phosphate bone substitutes are widely used for providing support for the in-growth of hard tissue in various medical applications (e.g., dental, orthopedic). Recently, research involving bone substitutes with interconnected open pore structures has focused on improving the mechanical properties of the substitutes and modifying their surfaces with proteins (e.g., collagen, bone morphogenetic protein) to induce early bone formation. In particular, it is highly desirable to develop a functional gradient-structured bone substitute that has the potential to control the bioresoption rate. A porous BCP scaffold was fabricated by the sponge replica method using a PU sponge. The sponge was dip coated three times followed by oven drying, burning out, and microwave sintering. Several approaches were used to fabricate a functional gradient scaffold. TCP was synthesized using the sol-gel process, and it infiltrated into the pore channel that formed after the burning out of the PU sponge. X-ray diffraction analysis characterized the phase identification of the BCP scaffold. Microstructures of the composites were observed using scanning electron microscopy.
Nano-Hardness Testing of Wear Particles in Sheep Knee Joints
Authors: Allen Christopher , Peng Zhong Xiao , Yin Ling , Carmichael Emma
Published: June 2010

This work aimed to establish a suitable procedure for establishing wear particle hardness and to investigate if the hardness of articular cartilage wear particles increases with increasing grades of osteoarthritis. To achieve the goals a selection of fresh sheep knee joints were obtained and consequently worn in a specially designed wear simulator. Wear particles were then removed from the joint using a syringe and prepared for hardness testing. In order to test the hardness of the wear particle samples nanoindentation was used. Once completed statistical analyses and correlation analyses were performed in order to find any relationships present. This was the first time that the hardness of the wear particles was tested and studied. As a result of the tests performed a general relationship between wear particle hardness and osteoarthritis grade was able to be determined. It was also determined that further work needed to be conducted on the experimental procedure to increase the accuracy of the results obtained.
3D Characterisation of Grain Deformation under Synchrotron Radiation
Authors: Kobayashi Masakazu , Toda Hiroyuki , Uesugi Kentaro , Takeuchi Akihisa , Suzuki Yoshio
Published: June 2010

Recently, three-dimensional (3D) observation and analysis have attracted considerable attention in materials science field. By using the synchrotron radiation, the tomography makes possible high-resolution 3D observation dynamically and the recent diffraction analysis is available for 3D orientation mapping. In this study, grain deformation behavior in polycrystalline aluminum alloy has been characterized by 3D observation method applying the synchrotron radiation. The method to measure inner strain distribution by means of microstructural features tracking provides strain distribution within the sample, which we could not access before. The effect of grain orientation and its interaction during tensile deformation was discussed with the obtained strain distribution.
Characterization of Crack-Tip Dislocations and their Effects on Materials Fracture
Authors: Higashida Kenji , Tanaka Masaki , Sadamatsu Sunao
Published: June 2010

Three-dimensional structure of crack tip dislocations were investigated by combining scanning transmission electron microscopy (STEM) and electron tomography (ET) in silicon single crystals. P-type (001) silicon single crystals were employed. <110> cracks were introduced from an indent on the (001) surface. The specimen was heated at 873K in order to introduce dislocations at the crack tips. The specimen was thinned to include the crack tip in the foil by an iron milling machine. STEM-ET observation revealed the three-dimensional structure of crack tip dislocations. Their Burgers vectors were determined by using an invisibility criterion. The local stress intensity factor was calculated using the dislocation characters obtained in the observation in this study, indicating that the dislocations observed were mode II shielding type dislocations.
The Study on the Nucleation Behaviours in IF Steel by 3-D EBSD Tomography
Authors: Xu Wan Qiang , Ferry Michael
Published: June 2010

3-D FIB-EBSD tomography was used to analyze the structure and crystallography of nuclei, and nucleation process in 3-D space during annealing a cold rolled IF steel. It is revealed that the structure of nucleus at its very initial formation stage can be divided into two parts: (1) nucleation core, having a dislocation-contained subgrain structure, mainly bounded by low angle grain boundary with surrounding deformation subgrain, (2) newly-grown region, having a dislocation free structure, formed from high store energy deformation structures surrounding nucleus, and mainly bounded by high angle grain boundary.
Hot Ductility of High Carbon Steel Produced by CSP
Authors: Huang Gang , Jiao Guo Hua , Wen De Zhi , Zhou Chun Quan , Wu Kai Ming
Published: June 2010

Hot ductility of a high carbon steel 65Mn produced by CSP (Compact Strip Production) was tested on Gleeble-3500 simulator. Results show that the great reduction of hot ductility occurred between 700°C900°C. This is resulted from the formation of ferrite allotriomorphs along prior austenite grain boundaries and aluminum nitride precipitation along and near austenite grain boundaries. In order to prevent from surface cracking on thin slabs, it is suggested that the unbending temperature should be controlled above 950°C.
Texture Distribution and Development through the Thickness of Grain Oriented Silicon Steel
Authors: Wang Zhi Fen , Han Rong Dong , Li Ping He , Liu Ji Xiong , Sun Yi Qiang
Published: June 2010

The texture distribution and development of grain oriented silicon steel with different production stages have been investigated by electron backscatter diffraction technique (EBSD). The results indicated that below the surface the intensity of {001}<110> of α-fiber was strongest with a amount of {110}<001> texture and γ-fiber. After first cold rolling and normalizing, in the corresponding position the {110}<001> texture and γ-fiber appeared again. The {110}<001> grains and γ-fiber after decarb-annealing was helpful to accelerate the abnormal growth of second grain nucleation.
Challenges Associated with the Characterisation of Nanocrystalline Materials Using Atom Probe Tomography
Authors: Tang Feng Zai , Alam Talukder , Moody Michael P. , Gault Baptiste , Cairney Julie M.
Published: June 2010

Atom probe tomography provides compositional information in three dimensions at the atomic scale, and is therefore extremely suited to the study of nanocrystalline materials. In this paper we present atom probe results from the investigation of nanocomposite TiSi¬Nx coatings and nanocrystalline Al. We address some of the major challenges associated with the study of nanocrystalline materials, including specimen preparation, visualisation, common artefacts in the data and approaches to quantitative analysis. We also discuss the potential for the technique to relate crystallographic information to the compositional maps.
Characterisation of the Densification Mechanism of Plasma Sprayed Cordierite
Authors: Llorca-Isern Nuria , Bertran-Vidal Gemma
Published: June 2010

Free-standing samples of plasma sprayed cordierite with a high level of porosity were heat treated at different temperatures and for different holding times in order to study the densification process. Optimisation of a new characterisation methodology for the interconnected defects network in the specimens of plasma sprayed cordierite based on fluorescence confocal scanning laser microscopy (CSLM) information was the main objective of the present work. Optical, electron and confocal microscopes were use to determine percentage, distribution and morphology of the defects in the specimens. Fractal geometry combined to the CSLM images was useful for evaluating structural characteristics, complexity and level of connectivity of the defects network of these samples. All this information allowed studying the level of densification accomplished by the samples under the different thermal treatments conditions. After the evaluation of the results produced, this methodology can be validated for other applications or processes such as conventional sintering, etc. Results showed low percentage of porosity with dispersion the latter related to the degree of anisotropy of the samples. However an increase of porosity with the crystallisation was also observed.
Effect of Alumina Starting Materials on Spheroidization in Flame Fusion Method
Authors: Eom Sun Hui , Pee Jae Hwan , Lee Jong Keun , Hwang Kwang Taek , Cho Woo Seok
Published: June 2010

Alumina powder is used to improve the heat conduction and physical properties of heat radiation sheets, these properties can be improved by increasing the filling rate of alumina. Spherical alumina powder is being actively developed to improve the filling rate of alumina in sheets. In this study, a high-temperature flame was created by the flame-fusion method using an oxygen burner to produce spherical alumina. We investigated how the chemical composition and particle size of starting materials affect their fusion behavior under flaming conditions during spherical alumina production using the flame-fusion method. Boehmite and aluminum hydroxide, which accompany the endothermic reaction due to the dehydration of the starting materials, showed lower spheroidization ratios than sintered alumina. The spheroidization ratio improved as the particle size of the starting materials decreased.
The Bonding Structure of the Various High Purity or Binderless Polycrystalline Cubic Boron Nitride Compacts Sintered at 5 to 7GPa and 1600 to 2000 °C
Authors: Akhmadi Eko , Minoru Akaishi , Itsuro Tajima
Published: June 2010

The cBN-cBN direct bonding structure of some cBN compacts made by the method of the direct conversion of the pyrolytic-BN (pBN) or wurtzite-BN (wBN) to cubic-BN at the pressure of 7GPa and temperature 2000 °C and the cBN compact made by the method of sintering the cBN powder along with polyvinylidene chloride (PVDC) at the condition of 5.5GPa and 1600 °C has been studied. The XRD, SEM, TEM analysis and the wear resistance on the ductile cast iron machining has been investigated. While the XRD analysis of the above cBN samples showed that all samples consist only of cBN, and the SEM observation showed that they all have the cBN-cBN direct bonding structure, A STEM analysis showed the existence of the impurities at the cBN crystal boundary. The starting materials and the sintering method affect the degree of these impurities.
Thermal Decomposition of Pyrite FeS2 under Reducing Conditions
Authors: Charpentier Ludovic , Masset Patrick J.
Published: June 2010

The thermal decomposition of pyrite was investigated under reducing atmosphere, e.g. p(O2)~10-6 bar. Thermogravimetric measurements were coupled with differential scanning calorimetry and mass spectrometry. Multi-scan method was used to calculate the values of the activation energy of the reaction of thermal decomposition of the pyrite. It was shown that the value of the activation energy of the decomposition of pyrite into pyrrhotite varies with the reaction progress. The values of activation energy vary from 250 to 350 kJ.mol-1.
Preparation of Highly Crystalline Mesoporous TiO2 by Using Carbon to Protect the Pore Structure at Elevated Temperature
Authors: Zhu Yu Dan , Ding Yu Lan , Lu Xiao Hua , Zhuang Wei , Lu Ling Hong
Published: June 2010

Mesoporous TiO2 with highly crystalline pore wall has an enormous potential for applications in photocatalysis, catalyst support, drug delivery, etc. However, with the sintering temperature increasing, the crystallinity of the pore wall increases while the mesopore structure tends to collapse. In this work, we presented a novel strategy for creating highly crystalline mesoporous TiO2 (MT800) by using carbon to protect the pore structure at elevated temperature. The structural characterization indicates that MT800 has highly crystalline anatase phase and processes high surface area. The photocatalysis performance was evaluated by organic degradation and the results show that MT800 has superior photocatalysis activity to the TiO2 (T800) calcined at 800°C without carbon, because of the synergies of crystallinity and mesostructure.
Studies on Estimating Methods of Polarization Performance for Coated Steel in Seawater
Authors: Qi Yu Hong , Zhang Zhan Ping , Miao Mei , Zhang Xia Zhen
Published: June 2010

The polarization curves and electrochemical impedance spectroscopy of coated steel after scratching cross-lines or cathodic polarization using COLT system connected to electrochemical workstation IM6ex in seawater are investigated and from the measured polarization data, potential distribution on hull surface under waterline are predicted using Beasy CP software. It is shown that an more pricise method for gaining polarization data of the coated steel in seawater is the electrochemical measurement carried out by COLT system and the method of scratching cross-lines or cathodic polarization for coating damage is simple and convenient for estimating the polarization data of a new coated hull that is closely related to the coating properties.
Mechanical Properties of Micro-Alloyed TRIP Steel
Authors: Jung Jae Hyuk , Kim Sun Gil , De Cooman Bruno C.
Published: June 2010

The micro-alloying concepts have been widely used as a way to optimize the microstructure evolution and improve mechanical properties of conventional constructional steels. In the current study, the effect of micro-alloying on the properties of a multi-phase TRIP steel is analyzed. The micro-alloying of TRIP steel was found to lead to an increase of the yield stress rather than the tensile strength. A physical metallurgical explanation of the effect is proposed.
Post-Hydrogen Permeation Characterization of V-Based Crystalline Alloy Membranes
Authors: Song Guang Sheng , Dolan Michael , Liang Daniel , Kellam Michael
Published: June 2010

The surface preparation and hydrogen embrittlement in particular are research challenges facing the practical application of vanadium alloy membranes. These two issues are addressed by surface characterization and fracture analysis in order to find the reasons why delamination and crack failures occur during hydrogen permeation. Post-failure analysis of the hydrogen-induced cracking membrane specimen suggests a new failure mechanism for hydrogen embrittlement.
Nanoindentation Characterization of Intermetallics Formed at the Lead-Free Solder/Cu Substrate Interface
Authors: Tsukamoto Hideaki , Dong Zhi Gang , Huang Han , Nishimura Tetsura , Nogita Kazuhiro
Published: June 2010

The intermetallics of Cu6Sn5 that are formed at the Sn-based solder/ Cu substrate interface play a significant role in solder joint reliability. The characterization of the mechanical properties of the interface Cu6Sn5 is essential to understand the mechanical performance and structural integrity of the solder joints. In this study, the interface Cu6Sn5 and (Cu,Ni)6Sn5 formed in Sn-Cu and Sn-Cu-Ni ball grid array (BGA) joints were investigated using nanoindentation. The results demonstrated that the strain rate sensitivity and the activation volume of these intermetallics were affected by the reflow times and load conditions. The strain rate sensitivity of Cu6Sn5 and (Cu,Ni)6Sn5 were estimated from 0.023 to 0.105, and the activation volume of Cu6Sn5 and (Cu,Ni)6Sn5 were estimated from 0.128 b3 to 0.624 b3 (b=4.2062x10-9 m) for 1, 2 and 4-reflowed Sn-Cu (-Ni) samples.
Micro-Scratching of UHMW Polyethylene Surfaces
Authors: Liu Yan Yan , Gladkis Laura G. , Timmers Heiko
Published: June 2010

Ultra-high molecular weight polyethylene has been micro-scratched with 90° cube corner tips. The scratch mode was flat-on, uni-directional and single pass. The micro-scratches and cross-sectional scratch profiles were characterised with atomic force microscopy. No detached debris is produced. Cross-sectional scratch profiles have been analysed using Zum Gahr’s formalism giving an fab ratio slightly above zero. This is consistent with expectation for ductile polymers where none or little detached debris is produced. However, the observation contrasts with that for other polymers, such as PMMA, PEP and PC, for which inconclusive results suggest an excess pile-up implying an inconceivable change of mass density or material gain.
A New Micromechanical Elasto-Plastic Constitutive Model for Fiber-Reinforced Composite Laminates
Authors: Zhang Hua Shan , Zhang Yi Xia
Published: June 2010

A micromechanical elastic-plastic bridging constitutive model is developed in this paper for accurate representation of material behavior of fiber-reinforced composite laminates. In the bridging constitutive model, elastic behavior is represented by bridging matrix elements and interaction between the average stresses in matrix with those in fibers are included. A transient plastic bridging matrix is developed to describe accurately the elastic-plastic material properties of the fiber reinforced composites, and the effects of the material parameters of matrix and fiber on the bridging matrix elements have been accounted for. The proposed constitutive model is validated against experiment investigation.
Fatigue Fracture Behavior of ARB Processed Aluminum
Authors: Kitahara Hiromoto , Horike Takuya , Tsushida Masayuki , Ando Shinji , Tsuji Nobuhiro
Published: June 2010

Fatigue crack propagation behaviors of ultrafine grained (UFG) Al sheets fabricated by the accumulative roll bonding (ARB) process were investigated. The ARB process was carried out up to 6 cycles (equivalent strain, eq.=4.8). The ARB processed sheet had lamellar boundary structure elongated to rolling direction of the sheet. The mean spacing of the boundaries was 182 nm. The tensile strength of the starting Al sheet increased after the 6-cycle of the ARB. Fatigue crack growth tests were performed to clarify the crack growth rate and threshold stress intensity factor range for crack growth (Kth). The fatigue crack profile in the ARB processed sheet differs from that in the starting Al sheet. The Kth of the ARB processed sheet was smaller than that of the starting sheet. The Kth of Al would decreased with decreasing the crack closure phenomena after the 6-cycle of the ARB. The fatigue crack growth rate test shows that the critical load for starting to propagate the fatigue crack and the fatigue crack growth rate decreased by ultrafine grain refinement.
Microstructure Features and Contact Fatigue Crack Growth on Rail
Authors: Seo Jung Won , Kwon Seok Jin , Jun Hyun Kyu , Lee Dong Hyung
Published: June 2010

Rolling Contact Fatigue (RCF) damage on the surface of rails such a head check, squats is a growing problem. Since rail fractures can cause derailment with loss of life and property, the understanding of rail fracture mechanism is important for reducing damages on the rail surface. In this study, we have investigated RCF damage, fatigue growth and fracture surface morphology on the surface of broken rail using failure analysis and finite element (FE) analysis. The investigation indicates that the crack grows at about 20° to the depth of 8mm from the surface and branches into two cracks. One crack propagates downward at about 47°, the other propagates upward. Since the crack growth rate of the downward crack was faster than that of upward crack, rail eventually was broken. Since the downward branches lead to fracture of the rail, they are more dangerous to the integrity of rails. It has been observed that White Etching Layer (WEL) occurs within the surface of broken rail. It was found that the fatigue crack initiation and propagation was accelerated by WEL.
Evaluation of Residual Stress of Railway Wheel Regarding to Deterioration
Authors: Kwon Seok Jin , Lee Dong Hyung , Seo Jung Won , Kwon Sung Tae
Published: June 2010

Upon investigation of the damaged wheels it was determined that the cracking was caused by thermal fatigue during on-tread friction braking. The thermal cracks appear as short cracks oriented axially on the wheel tread. Severe heating of the wheel tread during braking was believed to be a contributing the variation of residual stress which is related to wheel failure. It is necessary to evaluate the residual stress due to deterioration of wheel tread in order to ensure the safety of wheel.
In the present paper, the residual stress of railway wheel for deterioration using x-ray diffraction system is evaluated. The result shows that the residual stress of wheel is depend on the running distance and the residual stress needs to be inspected between the wheel diameter of 800 and 780mm.
Hot-Rolled TRIP Steels Based on Dynamic Transformation of Undercooled Austenite
Authors: Yang Wang Yue , Li Long Fei , Yin Yun Yang , Sun Zu Qing , Wang Xi Tao
Published: June 2010

A novel thermomechanical process to manufacture hot-rolled transformation-induced plasticity (TRIP) steels was developed based on dynamic transformation of undercooled austenite (DTUA). Between DTUA and the isothermal bainitic treatment, only one-step controlled-cooling was required. The microstructure evolution of hot-rolled C-Mn-Si and C-Mn-Al-Si TRIP steels based on DTUA was investigated by hot uniaxial compression tests using a Gleeble1500 simulation test machine. The results indicated that during DTUA, the kinetics of ferrite formation was fast, the volume fraction of ferrite formed was determined by applied strain. In comparison with the process based on static transformation of austenite, a more uniform multiphase microstructure with fine ferrite grains was formed, the bainite packets were small and had relatively random orientations, the retained austenite distributed uniformly and had relatively high volume fraction. Hot-rolled TRIP steels based on DTUA demonstrated better mechanical properties, especially for C-Mn-Al-Si TRIP steel.
Hydrogen Evolution Behavior during Tensile Deformation in Austenitic Stainless Steels Exposed to High Compressed Hydrogen Atmospheres
Authors: Horikawa Keitaro , Kobayashi Hidetoshi , Kanno Motohiro
Published: June 2010

Hydrogen embrittlement sensitivity of austenitic stainless steels, SUS316L and SUS310S exposed to high compressed hydrogen gas atmospheres was evaluated by means of a slow strain rate testing (SSRT) in air. Hydrogen evolution behavior during tensile deformation and fracture was also investigated by using a testing machine equipped with a quadrupole mass spectrometer installed in an ultrahigh vacuum chamber. When the SUS 316L specimen with hydrogen gas charging were deformed at a very slow crosshead speed of 1.67 nm/s, local deformation was promoted as compared to the specimen without hydrogen gas charging. On the other hand, no decrease of the ductility was observed in the SUS310S specimen with hydrogen gas charging even in the SSRT. In the hydrogen charged SUS316L specimen, the amount of continuous hydrogen evolution throughout deformation was much higher than that in the specimen without hydrogen gas charging. In addition, sudden hydrogen evolutions were sometimes identified in the SUS316L specimen with hydrogen gas charging during the deformation.
Failure Analysis on the Rivet
Authors: Yu Hong Ya , Zeng De Chang , Liu Zhong Wu
Published: June 2010

This paper presents a detailed failure analysis on a rivet, which broke into two parts from the joint place between head and shank under a load of seven tons during service, by the combination of optical microscopy, SEM and EDS. The metallographic examination shows some micro-inclusions in the sample and many micro-cracks along the grain boundaries. SEM and EDS results show that the surface of the rivet was plated with a zinc coating and it was eroded severely. The fracture surface exhibits the characteristic of quasi-cleavage fracture, indicating an intergranular brittle fracture mode. Some micro-pores were found on the facets of intergranular cracked grains. Most importantly, the Crow-toe Pattern, one of river patterns or hairline seams, which is a typical microstructure of hydrogen embrittlement, was observed on the fracture. Based on above analysis, it is concluded that the failure of the rivet is caused by the hydrogen embrittlement. The hydrogen, most likely, comes from the zinc plating process. Due to the aggregation and diffusion of hydrogen into the matrix, the brittle cracking happens in the regions with stress concentration because of the volume expansion effect under the external force.
Selective Oxidation and Sub-Surface Phase Transformation during Austenitic Annealing of TWIP Steels
Authors: Gong Yong Feng , Kim Han Soo , Kim Sung Kyu , De Cooman Bruno C.
Published: June 2010

The selective oxidation of Al-free and Al-added Twinning Induced Plasticity (TWIP) steels during full austenitic annealing at 800°C in N2+10%H2 atmosphere at a dew point of -17°C was investigated by means of HR-TEM of FIB cross-sectional samples. For Al-free TWIP steel, a dense MnO layer was formed on the surface. Crystalline c-xMnO.SiO2(x2) particles and amorphous a-xMnO.SiO2(x<0.9) particles were found at the MnO layer/steel matrix interface. In the subsurface, Mn depletion resulted in the transformation of the austenite to the ferrite phase in a narrow zone. For Al-added TWIP steel, a continuous outer MnO layer and a transition layer consisting of amorphous a-xMnO.SiO2(x<0.9) and crystalline c-MnO.Al2O3(0.8<x<1.2) were formed. The interface between the a-xMnO.SiO2(x<0.9) and c-MnO.Al2O3(0.8<x<1.2) layers had rough structure and 20~50nm diameter voids were formed at the interface. Meanwhile, a narrow Mn-depleted ferrite layer was also formed in the subsurface. The void formation is very likely related to Kirkendall effect occurring during the oxides formation. The thick MnO layer and the voids constitute major challenges to the successful hot dip galvanization of TWIP steels in industrial HDG lines.
Effect of Humidity and Thermal Cycling on Carbon-Epoxy Skin/Aramid Honeycomb Structure
Authors: Yeo Eudora Sia Ying , Wang John , Mirabella Leo , Rider Andrew N.
Published: June 2010

Many modern military aircraft are constructed from composite and bonded structure, such as thin carbon-epoxy laminate bonded to Kevlar® and Nomex® honeycomb. Operation of these platforms in Australian and global conditions will subject the structure to potentially high levels of humidity, extremes in temperature, and for maritime operations, exposure to salt spray conditions. The thin composite laminate is likely to rapidly absorb moisture in a humid environment and enable permeation of moisture into the adhesive and core. In addition to the chemical influence of moisture on the composite structure, the moisture trapped in the honeycomb structure may freeze and expand with changes in altitude during operations or simply due to daily temperature fluctuations at the resident airbase. The combination of moisture ingress in the honeycomb structure and thermal cycling may lead to deteriorated strength of the honeycomb panels over time that would not be observed for long term humid exposure alone. Long term salt water absorption may also have an adverse effect on composites structures. This study investigates the effects of humid environments and thermal cycling on the mechanical properties of composite and honeycomb structures.
Strength Evaluation of Bolted Connection in PFRP Structural Member
Authors: Lee Young Geun , Lee Seung Sik , Nam Jeong Hun , Kim Hong Taek , Yoon Soon Jong
Published: June 2010

Fiber reinforced plastic structural shapes are readily available in civil engineering applications. Especially, pultruded fiber reinforced plastic is an attractive construction material for structural applications because it can be produced in mass production, and it has good mechanical and chemical properties compared with existing conventional structural materials. To be used in the construction field, connection of the pultruded structural member is unavoidable. Bolted connections may be the most suitable option for civil engineering applications compared with bonded connection. However, bolted connection has disadvantages such as reduction of strength due to bolt holes in the connection. Experimental and analytical studies on the bolted connection of PFRP plated member have been carried out. Four different types of connection distinguished by number and arrangement of bolt holes are investigated. Geometrical test parameters are edge distance, width, and longitudinal and transverse spacing. The effects of the parameters are evaluated and quantified based on the observations, such as failure load and failure mode, obtained from the experiment. In addition to the experimental investigation, analytical study is also conducted to predict the failure load of the member with bolted connection.
An Experimental Investigation on the Structural Behavior of FRP-Concrete Composite Compression Members
Authors: Park Joon Seok , Kang In Kyu , Park Jong Hwa , Park Joo Kyung , Kim Hong Taek , Yoon Soon Jong
Published: June 2010

In construction industries, new construction materials are needed to overcome some problems associated with the use of conventional construction materials due to the change of environmental and social requirements. Accordingly, the requirements to be satisfied in the design of civil engineering structures are diversified. As a new construction material in the civil engineering industries, fiber reinforced polymeric plastic (FRP) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. Nowadays, new types of bridge piers and marine piles are being studied for new construction. They are made of concrete filled fiber reinforced polymeric plastic tubes (CFFT). In this paper, a new type of FRP-concrete composite pile which is composed of reinforced concrete filled FRP tube (RCFFT) is proposed to improve compressive strength as well as flexural strength of an RCFFT. The load carrying capacity of proposed RCFFT is discussed based on the result of experimental and analytical investigations.
Thermal Decomposition and Kinetic Study on Different Types of Glass Fiber/Unsaturated Polyester Pipe Waste
Authors: Saetiaw Kaew , Atong Duangduen , Sricharoenchaikul Viboon , Aht-Ong Duangdao
Published: June 2010

Three types of unsaturated polyester matrix, ortho phthalic, iso phthalic, and vinyl ester, reinforced with glass fiber laminated composite waste have been subjected to investigate thermal decomposition behavior and kinetic parameters using non-isothermal thermogravimetric analysis from an ambient to temperature 900°C under nitrogen atmosphere at the passing flow rate of 20 ml/min. The results showed that the major decomposition range of the unsaturated polyester matrix was from 260 to 445°C, depending on a heating rate and the different types of polyester matrix. Regarding their chemical structure, ortho phthalic polyester started to degrade at lower temperature (260-280°C) than iso phthalic and vinyl ester (300-350°C). The remaining solid residual contained glass fiber which could not degrade under experimental conditions. The maximum rate of weight loss was increased with increasing heating rate. The activation energy for decomposition of ortho, iso phthalic, and vinyl ester composites was 168, 172, and 176 KJ/mol, respectively.
Performance of Aluminium / Vinylester Particulate Composite
Authors: Epaarachchi Jayantha Ananda , Reushle Matthew T.
Published: June 2010

The performances of aluminum /vinylester particulate-composites were studied in detail in order to investigate its suitability for engineering applications. This study examined the suitability of atomised aluminum particles for particulate reinforcement of a vinyl ester resin. Mechanical properties were obtained for the composite by testing various percentages of aluminium powder (75-150 m) and vinylester resin. It has been found that the inclusion of Al powder has not significantly changed the properties of vinylester resin, however an improvement in the ductility of the composite has been recorded. The optimal performances of the composite were exhibited by 15% Al composition. The properties of the particulate composites were modeled using numerous empirical models. Unfortunately a significant difference was found between some of the experimental and predicted properties of the Al/vinylester particulate composite. This paper intends to detail the variation of mechanical properties with the change of Al volume fraction in the composite and the performances of empirical models in prediction of the properties of particulate composites.
Modelling of Reinforced Asphalt Products for Road Applications
Authors: Vuong Binh T. , Choi Sing Ki , Hoque Zahid
Published: June 2010

New technology of reinforcement materials in asphalt overlays can offer a potentially cost effective solution for treating cracked pavements. To date, however, there is no design process allowing the use of available reinforcement products in road applications in Australia; whereas overseas design procedures are not readily available. A new 3D finite element (FE) analysis procedure was considered where reinforced asphalt layer is modelled as a thin 3D compound non-homogeneous layer which is then converted into a 3D orthotropic membrane. This procedure was used to analyse performance of three reinforcing products for road applications in Australia and results indicated that it is possible to predict and compare “retard reflection cracking” performance of various reinforced products.
High Strength and Lead-Free Machinable Brass by Powder Metallurgy Process
Authors: Imai Hisashi , Li Shu Feng , Kousaka Yoshiharu , Kojima Akimichi , Atsumi Haruhiko , Kondoh Katsuyoshi
Published: June 2010

Copper-40mass%zinc (Cu-40Zn) brass alloy powder containing 1.0 mass% Cr was prepared by the water atomization. Graphite particles, having a mean particle size of 5 μm, were added to the as-atomized powders by the ball milling equipment for 4h under 120 rpm. Spark plasma sintering process was used to consolidate the above elemental mixed powders (sintered material). Sintered materials were heat-treated for the precipitation of much Cr (HT material). The machinability of Cu-40Zn brass alloys was evaluated by a drilling test using a drill tool under dry conditions. The matrix hardness of sintered material was higher than that of HT material. On the other hand, the machinability of sintering material was higher than that of HT material. There is no trade-off relationship between the matrix hardness and machinability of the brass alloys. SEM-EDS observation indicated that Cr content dissolved in the brass matrix of sintered material and HT one was 0.42 mass% and 0.19 mass%, respectively. As the reason why machinability of HT material lowered, the precipitation of the hard Cr particle or generation of Cr-C compound caused to inhibit the machinability.