bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Small Addition of Si on Superplastic Elongation at Room Temperature in Zn-Al Eutectoid Superplastic Alloy
Authors: Kamiya Yuhei , Ninomiya Masaki , Uesugi Tokuteru , Takigawa Yorinobu , Higashi Kenji
Published: May 2014

Recent experimental data have revealed that a small amount of impurity can significantly influence the superplastic behavior in Zn-Al eutectoid superplastic alloy. However, the effect of Si content on the superplastic behavior in Zn-Al alloy has not been reported. In this study, the superplastic behavior at a room temperature of two grades of the Zn-Al eutectoid superplastic alloy was studied under identical conditions of grain size, temperature, and strain rate. These two grades were prepared from high-purity Zn, Al and Al-Si alloy using the same procedure but different Si impurity levels; Zn-Al-10Si and Zn-Al-1000Si contain 10 and 900 wt. ppm of Si, respectively. As a result of annealing treatments, an average grain size of 0.6 μm in both grades. To investigate the effects of Si content on superplastic properties, the tensile tests were performed at a room temperature of 298 K and a constant strain rate of 1×10-3 s-1. Microstructures before and after the tensile tests was observed using a scanning electron microscope. The experimental results show that the elongations decreased with increasing the Si content. In contrast, the flow stress of Zn-Al alloys was not affected by the Si content. On the microstructure observation of the two grades of the Zn-Al alloy before and after the tensile tests, cavities existed at grain boundaries and strain enhanced grain growth was observed.
Crystallographic Features of the Charge-Orbital-Ordered State in the Highly-Correlated Electronic System Ca1-xPrxMnO3
Authors: Kojima Kentaro , Inoue Yasuhide , Arao Masazumi , Koyama Yasumasa
Published: May 2014

The charge-exchange-type orbital-ordered (CEOO) state accompanying antiferromagnetic ordering has been reported in the highly-correlated electronic system Ca1-xPrxMnO3 (CPMO) with the simple perovskite structure. The feature of the CEOO state in CPMO is that the state is present in the wide Pr-content range of 0.30 ≤ x ≤ 0.70. Although the Zener-polaron model was proposed for the CEOO state at x = 0.60, the detailed features of the CEOO state, particularly for lower Pr contents, have not been understood sufficiently. We have thus investigated the crystallographic features of the CEOO state in CPMO with 0.40 ≤ x ≤ 0.50, mainly by transmission electron microscopy. It was found that, when the temperature was lowered from the disordered state, incommensurate satellite reflections characterizing the CEOO state appeared in electron diffraction patterns below about 250 K in CPMO. The careful analysis of the reflections indicated that the CEOO state for 0.40 ≤ x ≤ 0.45 was different from that for 0.45 ≤ x ≤ 0.50. Concretely, the former CEOO state accompanied only a transverse lattice modulation, while both transverse and longitudinal modulations with different wave vectors appeared in the latter state. This implies that the state for 0.40 ≤ x ≤ 0.45 can be regarded as an orbital-modulated (OM) state without a charge modulation. It is thus understood that an increase in the Pr content leads to the OM-to-CEOO state change below about 250 K around x = 0.45.
Thermo-Kinetic Simulation of the Yield Strength Evolution of AA7075 during Natural Aging
Authors: Lang Peter , Weisz Thomas , Ahmadi Mohammad Reza , Povoden-Karadeniz Erwin , Falahati Ahmad , Kozeschnik Ernst
Published: May 2014

The yield strength evolution in aluminum alloy 7075 is investigated during natural aging. The thermo-kinetic simulation, capable of predicting nucleation, growth, coarsening and dissolution of metastable and stable hardening precipitates in Al-Zn-Mg-Cu during natural aging, is outlined briefly. A recent strengthening model for shearing and bypassing of precipitates by dislocations is utilized to calculate the evolution of the macroscopic yield strength at room temperature. The simulation accounts for vacancy-solute binding energies calculated with the help of first principles simulations that influence the diffusivity of the system due to the presence of excess quenched-in vacancies. These results provide predictions about the amount of excess vacancies trapped by solid solution alloying elements and how the lifetime of vacancies changes due to attractive or repelling binding forces between vacancies and different solid atoms in the aluminum matrix. In our approach, we calculate the strength evolution after quenching due to interaction between dislocations and changes in the microstructure by precipitation of different kinds of secondary phases. The predicted evolution of yield strength is finally verified on experimental measurements.
Microstructural Characterization of Hydrogen Induced Cracking in TRIP Steels by EBSD
Authors: Laureys A. , Depover Tom , Petrov Roumen , Verbeken Kim
Published: May 2014

The present work evaluates hydrogen induced cracking in a high strength TRIP steel with a complex multiphase microstructure, containing ferrite, bainite, retained austenite, and some martensite. Each structural constituent demonstrates a different behavior in the presence of hydrogen and when deformed, the retained austenite transforms to martensite. The goal of this work is to understand the response of the hydrogen saturated multiphase structure to a mechanical load. A tensile test on notched samples combined with in-situ electrochemical hydrogen charging was carried out. The test was interrupted at certain specific points, before the macroscopic failure of the material. Hydrogen induced crack initiation and propagation were examined by studying several intermediate elongations. The microstructure of the samples was characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The EBSD measurements allowed both microstructural and crystallographic characterization of the hydrogen induced crack surroundings. A correlation was found between the occurrence of martensite, which is known to be very susceptible to hydrogen embrittlement, and the initiation of hydrogen induced cracks. These cracks were located at the surface in specific high stressed regions. Finite element simulations indicated that these regions were induced due to the presence of the notch.
A Positron Emission Particle Tracking (PEPT) Study of Inclusions in Liquid Aluminium Alloy
Authors: Burnard D.J. , Caden A.J. , Gargiuli J. , Leadbeater T. , Parker D.J. , Griffiths William D.
Published: May 2014

Inclusions have a detrimental effect upon casting properties but it is known empirically that a slow liquid metal flow has a beneficial effect by reducing the number of inclusions entering the casting. Positron Emission Particle Tracking (PEPT) is a method that can be used to track the path taken by radioactive particles, and can be used to follow the behaviour of inclusions as they make their way from a furnace, along the launder and into the casting. A new PEPT camera geometry was developed and used to track radioactively labelled γ-alumina particles, in the region of 600 μm size. The camera detectors were arranged radially around a launder, into which was poured 150 kg of liquid Al alloy, the radioactive particles being released at intervals during the pour. The positron camera was 0.7 m in length and 0.1 m2 in cross-sectional area, and this matched the dimensions of an industrial launder. A model of inclusion behaviour in a flowing liquid Al alloy was also developed, and the Positron Imaging system described was used to validate this model.
Anodic Bonding Mechanism of Pyrex Glass and Kovar Alloy and its Residual Stress Analysis
Authors: Liu Cui Rong , Chen Hui Qin , Li Juan , Meng Qing Sen
Published: May 2014

Anodic bonding experiments of Pyrex glass and Kovar alloy have been carried out in this investigation. By means of SEM and EDS, microstructures and chemical elements in the joining interfaces were analyzed. With XRD, phase structures in the interfaces were also analyzed. The results show that the joint is made up of three different layers, which are Kovar alloy layer, transition layer and Pyrex glass layer. The transition layer are spinal oxides, which are FeO·SiO2. By means of MARC software, residual stresses and strains were investigated for the anodic bonding samples of Pyrex glass/Kovar alloy. The maximum residual stress located in the transition layer and the maximum strain located in the Kovar alloy layer. Residual stresses and strains of the sample are significant small and uniform.
Effect of Strain Hardening on the Joint Efficiency of an Al-Mg-Sc-Zr Alloy Subjected to Friction Stir Welding
Authors: Malopheyev Sergey , Kulitskiy Vladislav , Mironov Sergey , Zhemchuzhnikova Daria , Kaibyshev Rustam
Published: May 2014

The microstructure and mechanical properties of friction stir welded Al-5.4Mg-0.2Sc-0.1Zr alloy were studied. Defect-free welds were produced in hot extruded, hot rolled and cold rolled initial conditions. Friction stir welding led to the formation of ultrafine-grained structure in stir zone that contributes to overall strengthening. Coherent Al3(Sc,Zr) dispersoids retain partially during welding process that provides a joint efficiency close to 100% in the hot extruded and hot rolled materials. In the cold-rolled state the joint efficiency was found to be only 64%. The relatively low weld strength of the cold rolled material was attributed to the elimination of strain hardening due to the formation of recrystallized structure. It was shown that full strength weld can be achieved in semi-finished products of Al-Mg-Sc alloys in cold-worked and stabilized states being equal to H323 and H341 tempering by friction stir welding.
Effect of HPT on Age-Hardening Behavior in Cu-Added Excess Mg-Type Al-Mg-Si Alloys
Authors: Maruno Shun , Saikawa Seiji , Shoichi Hirosawa , Hamaoka T. , Horita Z. , Lee S. , Terada Daisuke , Matsuda Kenji
Published: May 2014

Severe plastic deformation (SPD) techniques such as high pressure torsion (HPT) have been extensively researched to achieve. SPD process makes use of the plastic deformation where no change in the cross-sectional dimension of a work piece occurs during straining.In this work, the effect of HPT on aging behavior and microstructure in excess Mg-type Al-Mg-Si alloys including Cu. These alloys were investigated by hardness test and TEM observation. The results show that processing by HPT leads to significant grain refinement with a grain size of ~250nm. Age-hardening phenomenon is observed at 343K and 373K for the Al-Mg-Si alloys with HPT. A few density of dislocation in the crystal grain was observed. The typical needle-shaped precipitates of Al-Mg-Si alloys were not observed in the matrix.
Solid State Bonding of Al Alloy/SUS304 by Metal Salt Generation Bonding Technique with Acetic Acid
Authors: Matsubara Kota , Koyama Shinji , Nagata Hideo , Suda Yoshiyuki , Shohji Ikuo
Published: May 2014

The effect of surface modification on the tensile strength of the bonded interface of Al alloy and SUS304 stainless steel was investigated by SEM observations of interfacial microstructures and fractured surfaces. Aluminum surfaces were modified by boiling in 5% aqueous solution of NaOH for 20 s and 99.7% Acetic acid for 60 s. Bonding was performed at bonding temperature of 753 ~ 813 K under a pressure of 6 MPa (bonding time of 1.8 ks). As a result of surface modification, bonded joints were obtained at a bonding temperature 20 K lower than that required for non-modified surfaces, and the bonded strength was comparable to that of the maximum load.
HRTEM Observation of Age-Precipitation in Mg-2.9at.% Alloys
Authors: Matsuoka Yuki , Watanabe Katsumi , Saikawa Seiji , Ikeno Susumu , Matsuda Kenji
Published: May 2014

The magnesium alloy containing rare earth element is known to show good heat resistance. In this study, Mg-Y, Mg-Gd and Mg-Gd-Y alloys including the same total amount of solute elements have been investigated to clarified the effect of the Y atom on age-hardening and precipitation using HRTEM, SAED technique and HRTEM simulation. The diffuse scattering by SAED was obtained in as-quenched condition in all alloys. In the specimen at as-quenched condition, the row contrasts consisted of bright and dark dots lying on the {100}Mg planes, which were considered to mono-layer were observed by HRTEM.
Experimental and FEM Studies of the Relationships between Equal-Channel Angular Pressing Die Design, Strain Distribution and Pressing Forces
Authors: Sordi Vitor Luiz , de A. Mendes Filho A.A. , Valio Gustavo T. , Springer Phillip , Rubert José Benaque , Ferrante Maurizio
Published: May 2014

This paper addresses the influence of design on the performance of Equal-channel Angular Pressing dies, of which the important geometric parameters are the internal channel angle (Ф) and the curvature radii at this point. The investigation consists of FEM analysis (computational simulation) of the effect on die performance of the independent variation of the outer and inner curvature radii at the channels ́ intersection, plus the corresponding experimental validation (physical simulation). Using a Pb-62%Sn alloy, twelve R-r combinations were simulated and tested, keeping constant the Ф angle. Results indicated the best R-r combinations in terms of equivalent deformation level and homogeneity, together with the optimization of pressing forces.
Surface Characterization of Magnesium Anodized in a 10M KOH Electrolyte
Authors: Miller Christopher , Cipriano Aaron F. , Liu Hui Nan
Published: May 2014

Magnesium (Mg) is a promising implant material for orthopedic applications due to its biodegradability and desirable mechanical properties. However, in order for Mg to have widespread clinical applications, engineering solutions that address the rapid degradation in physiological environments and promote bone-forming activity are needed. The objective of this study was to develop an anodization process using a toxicant-free electrolyte to modulate nanoscale surface features and surface chemistry on Mg. Anodic polarization and potentiostatic anodization tests were used to evaluate the effect of applied potential on surface morphology of Mg in a 10 M KOH electrolyte. Nucleation of oxides as a function of anodization duration was also investigated in order to optimize the synthesis process. The alkaline electrolyte used for anodization of Mg offers an alternative to commercial processes that use hazardous elements. The anodized samples were annealed to investigate the effect of thermal treatments on surface morphology and chemical composition. The nanostructure and chemical composition of the anodized and annealed Mg substrates were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy. Our results showed that the nanostructures and chemical composition of anodically-generated oxide layers on Mg are specific to each oxidation process in a 10 M KOH electrolyte. Furthermore, results indicated that anodization durations of two hours generated surface oxide layers with homogeneous topography on the Mg substrates atapplied potentials of 0.5 V, 1.5 V and 2 V.. This study showed a promising approach for creating nanoscale surface features on Mg for improved bioactivity and degradation property.
Characterization of Magnesium Alloy Degradation in Whole Blood and Platelet Rich Plasma
Authors: Nguyen Thanh Yen , Guan Ren Guo , Cipriano Aaron F. , Zhao Zhan Yong , Liu Hui Nan
Published: May 2014

Magnesium (Mg) is an attractive biomaterial due to its desirable biodegradable and mechanical properties. In this study, we compared the degradation behavior of Mg and a new Mg alloy incubated in both whole blood and platelet rich plasma (PRP) for two hours under standard cell culture conditions. To avoid settling of red blood cells, tubes with whole blood were under constant rotation during the incubation. Post-incubation solutions were collected, centrifuged, and analyzed for pH and Mg ion concentration. Mg and Mg alloy samples were fixed with a 3% glutaraldehyde solution, dehydrated using an ethanol series, critical point dried, sputter coated, and imaged with a field emission scanning electron microscope. Analysis of the post-incubation solutions showed PRP had greater concentrations of Mg ions and higher pH values when compared with whole blood. This indicated that the Mg and Mg alloy degraded faster when incubated in PRP than in whole blood. When comparing the surface of the materials after incubation with whole blood and PRP, the surfaces of Mg and Mg alloy that was incubated in PRP had larger cracks and grain boundaries than the samples incubated in whole blood. Additionally, more particulate microstructures were observed on the samples incubated in PRP as opposed to whole blood. Further studies are still needed to elucidate the differences in degradation of Mg alloys in whole blood and PRP.
Effect of Cu/Ag Addition on Age-Precipitation in Two Step Aged Al-Mg-Si Alloys
Authors: Oe Y. , Matsuda K. , Nakamura J. , Ikeno S.
Published: May 2014

The effect of Cu or Ag addition on 2 step aging in Al-Mg-Si alloy has been investigated to understand precipitation for this alloy. The maximum hardness of two step aged alloy was higher with increasing pre-aging time for Al-Mg-Si alloy. There was no remarkable difference between the peak-hardness of the Ag addition alloy with and without pre-aging. The hardness decreased once for the Ag addition alloy aged at 473K just after pre-aged at 343K for 600ks and then increased to the peak hardness with increasing aging time, which means the reversion of the Ag addition alloy.
Cost Cut with High Impact Value of Sandwich Structure with Inexpensive ABS Core between High Strength CFRP Laminate Plies
Authors: Okada Takumi , Quan J.H. , Tsuchikura Naoya , Yamamoto Tatsuya , Kanda Masae , Faudree Michael C. , Nishi Yoshitake
Published: May 2014

Sandwich structural composites (CFRP/ABS/CFRP) of inexpensive acrylonitrile butadiene styrene (ABS) cores (2.0 mm thickness) between carbon fiber reinforced epoxy (CFRP) laminate plies (2.5 mm thickness) were suggested and prepared, since the materials cost of ABS resin was about 8% that of CFRP. Although Young’s modulus of CFRP/ABS/ CFRP is slightly smaller than that of CFRP, Charpy impact value (auc) of the CFRP/ABS/CFRP approximately corresponded to that of CFRP composite. Furthermore, applying homogeneous low voltage electron beam irradiation (HLEBI) to both side surfaces improved the auc of CFRP/ABS/CFRP. Since the irradiated depth estimated is about 119 ± 23 μm, the irradiation effects mostly acted within the CFRP sheet. The Charpy impact value (auc) of CFRP/ABS/CFRP at mid-fracture probability (Pf ) after irradiation at 0.30 MGy (kJg_1) was approximately 25 % higher than that before treatment. It was approximately equal to that for irradiated CFRP and was also about 20% higher than that of the CFRP before treatment. Although the use of ABS resin as the core reduced other mechanical properties of tensile and bending, the materials cost of CFRP/ABS/CFRP was approximately 25 % that of CFRP. Thus, the sandwich structural composites of CFRP/ABS/CFRP could be utilized for daily articles.
Influence of Impurities on Mechanical Properties of Electrodeposited Bulk Nanocrystalline Al
Authors: Ono Satoshi , Hanaoka Yudai , Matsui Isao , Takigawa Yorinobu , Uesugi Tokuteru , Higashi Kenji
Published: May 2014

Effect of typical impurities such as Fe, S, and Cl on mechanical properties of Al electrodeposited from a dimethylsulfone bath (DMSO2 bath) were studied. Electrodeposition from a DMSO2 bath was conducted to produce the bulk specimens with 0.08–0.24 at.% Fe, 0.47–0.84 at.% S, and 0.59–1.06 at.% Cl, varying the purity of aluminum chloride and current density. Decreasing the current density increased S contents and Cl contents, while the purity of aluminum chloride had no effect on chemical composition of the electrodeposits. The grain sizes were approximately 40–70 nm for Al electrodeposited from a DMSO2 bath. The grain sizes decreased with increase in S contents and Cl contents. The electrodeposited bulk nanocrystalline Al exhibited hardness values of 1.56–1.92 GPa. These values were higher than predicted values based on Hall–Petch equation of pure Al. Lattice parameter of samples was less than pure Al. According to Vegard’s law, Fe solute decreases the lattice parameter of Al. These results indicated that the hardness of the electrodeposited bulk nanocrystalline Al was affected by the reduction in the grain size and solid solution strengthening from the Fe contaminant.
Tempering of Direct Quenched Low-Alloy Ultra-High-Strength Steel, Part II – Mechanical Properties
Authors: Pallaspuro Sakari , Kaijalainen Antti , Limnell Teijo , Porter David A.
Published: May 2014

Direct quenched untempered ultra-high-strength structural steels can possess good toughness and weldability when based on low carbon contents. In this study, the influence of tempering at 500 °C has been investigated to evaluate the possibilities of widening the range of strengths that can be produced from one 0.1% C alloy composition. The study covered the four microstructural states presented in part I: direct quenched (DQ), reheated and quenched (RQ) and their tempered variants (DQ-T and RQ-T). In addition to tensile testing, the Charpy-V transition temperature T28J and the fracture toughness reference temperature T0 were determined for 6 mm thick specimens. The hardness of the DQ and RQ states was identical at ca. 400 HV. However, on tempering, the DQ state retained its hardness better than the RQ state with hardness values 346 HV (DQ-T) and 327 HV (RQ-T). The yield strengths of the DQ materials were ca. 100 MPa higher than those of the RQ materials both as-quenched and after tempering. Despite the higher strength of the DQ and DQ-T states, both had lower T28J temperatures than the RQ and RQ-T states mainly due to their finer effective grain sizes. The widely used correlation between the T28J and the T0 temperatures was not obeyed and the reasons for this are discussed.
RETRACTED: Modeling Mechanical Milling Process for Synthesis of Graphite Nanoparticles and their Characterization
Authors: Panjiar Himanshu , Gakkhar R.P. , Daniel B.S.S.
Published: May 2014

RETRACTED PAPER: The synthesis of graphite nanoparticles at ambient temperature by high energy mechanical milling is modelled using ANN (Artificial Neural Network). The effect of milling time on the evolution of particle size, inclusion, microstructure and morphology were examined using XRD (X-Ray Diffraction), EDS (Energy Dispersive X-Ray Spectroscopy), SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscope). ANN was effectively used to predict the influence of milling time on particle size and to forecast the milling time for the formation of nanoparticles. XRD results of investigation revealed change in strain behaviour of graphite particles of different sizes when heat treated.
Analysis of Plastic Deformation and Sample Geometry during the Compression Stage in High-Pressure Torsion
Authors: Pereira Pedro Henrique R. , Costa Túlio H.P. , Figueiredo Roberto B. , Cetlin Paulo Roberto , Langdon Terence
Published: May 2014

The production of ultrafine-grained metals through severe plastic deformation (SPD) has attracted significant interest in the scientific community due to the improvement in mechanical properties. Among SPD methods, high pressure torsion (HPT) processing is most effective in producing exceptionally small grains in disc-shaped samples subjected to high hydrostatic pressures and concurrent torsional straining. The present paper analyzes the elastic distortions and plastic flow during the application of compressive pressure in samples during HPT. Simulations through finite element method reveal a distortion of the initial shape of the sample and a gradient in sample thickness between the center and the edge due to elastic distortions. Also, it is shown that significant plastic deformation takes place in this stage and this is before any torsional deformation is imposed on the sample.
Interaction of V, Al, and N in Microalloyed Forging Steels after Hot Deformation
Authors: Rothleutner Lee M. , van Tyne Chester J.
Published: May 2014

A medium-carbon V-microalloyed steel (38MnSiVS5) with three different Al levels (0.006, 0.020, and 0.031 wt pct) was used to examine the interaction of V, Al, and N after hot deformation. A complete thermomechanical cycle was simulated in the laboratory using a Gleeble® 1500. Specimens were heated to a soaking temperature that varied from 1100 to 1250 °C for 5 or 45 min and control cooled to 1000 °C in 6 min, where they were compressed to 40 pct reduction at a strain rate of 1.0 s-1. After compression, the specimens were control cooled to 500 °C at 0.25 °C·s-1 and die quenched to room temperature. Additional specimens were processed without the compression step for comparison. The thermal and thermomechanically processed specimens were characterized by quantitative metallography and microhardness testing. The thermomechanically processed specimens with 0.006 wt pct Al maintained their hardness while reducing pearlite fraction by approximately 10 pct. The thermomechanical processed specimens with 0.020 and 0.031 wt pct Al showed a significant drop in microhardness and pearlite fractions, as compared to the thermal only processed specimens. The decrease in microhardness and pearlite fraction for the two higher-Al–containing alloys in both the thermal and thermomechanically processed specimens appears to follow the same linear trend, suggesting that AlN precipitation reduces the amount of N in solid solution, lowers the temperature at which V(C,N) precipitation occurs, and effectively reduces such strain-induced precipitation.
An Investigation of Mechanical Properties and Microstructural Evolution in an Aluminum Alloy Processed by Severe Plastic Deformation
Authors: Sabbaghianrad Shima , Langdon Terence
Published: May 2014

Processing by a combination of equal-channel angular pressing (ECAP) and high-pressuretorsion (HPT) was performed on disks of an Al-7075 alloy. The alloy was annealed at 753 K, processedby ECAP for totals of 4 passes and then processed by HPT under a pressure of 6.0 GPa up to amaximum of 20 turns. Measurements of Vickers microhardness showed reasonable hardnesshomogeneity after processing through 20 turns. It is demonstrated that the results from mechanicaltesting and microstructural analysis are consistent with the hardness measurements.
Structure and Properties of Cu Alloys Alloying with Cr and Hf after Equal Channel Angular Pressing
Authors: Shangina Daria , Maksimenkova Yulia , Bochvar Natalia , Serebryany Vladimir , Raab Georgy , Vinogradov Alexey , Skrotzki Werner , Dobatkin Sergey
Published: May 2014

Equal channel angular pressing (ECAP) results in grain-subgrain structure formation in Cu0.75 %Cr alloy with the average size of structure elements of 320 ± 73 nm Addition of hafnium into the Cu-Cr alloy leads to decrease of average size down to 225±82 nm and to increase of the high angle boundaries fraction from 40% to 53%. Microhardness of the Cu-0.7 %Cr-0.9 %Hf alloy is higher, than of the Cu-0.75 %Cr alloy, as after ECAP, so after heating when the aging processes occur in the temperature interval 400–550 °С. The strength in the tension tests of the Cu-0.7 %Cr-0.9 %Hf alloy after ECAP rises in 2.2 times compared with the quenched state. The aging leads to additional strength growth by 19%.
Effect of Annealing on Microstructure of Hydroxyapatite Coatings and their Behaviours in Simulated Body Fluid
Authors: Azis Sharidah Azuar Abdul , Kennedy John , Cao Peng
Published: May 2014

In this study, hydroxyapatite (HA) coatings on Ti6Al4V substrate were deposited using an ion beam sputtering technique. Owing to its medical applications, the crystalline phases present in the HA must be controlled. This study investigated the effect of post-deposition heat treatment at different temperatures and evaluated the microstructure of the HA coatings and their behaviours in simulated body fluid (SBF). The post-deposition treatment of the as-deposited samples was carried out in an air-circulated furnace at a temperature between 300 0C and 600 0C. The XRD patterns reveal that the minimum temperature to transform the HA coating from amorphous to crystalline phase is 400 0C. A higher temperature at 600 0C leads to a growth of the crystalline HA phases. Fourier transform infrared spectroscopy (FTIR) measurements show the existence of hydroxyl and PO-bonds in all coatings and the amounts varied with temperature. Atomic Force Microscopy (AFM) study suggests that the nanostructured crystalline HA starts to grow at 400 0C and becomes more obvious at a higher temperature of 600 0C. The simulated body fluid (SBF) test reveals that better apatite formation with post deposition heat treatment at 600 0C would potentially enhance the formation of new bone (osseointegration).
Microstructure of Er2O3 Coating Layer of Hydrogen Penetration Control
Authors: Shinkawa Takayuki , Sunada Satoshi , Hishinuma Yoshimitsu , Tanaka Teruya , Muroga Takeo , Ikeno Susumu , Matsuda Kenji
Published: May 2014

Erbium oxide (Er2O3) was shown to be a high potential candidate for tritium penetration barrier and electrical insulator coating for advanced breeding blanket systems such as liquid Li, Li-Pb or molten-salt blankets. Recently, Hishinuma et. al. succeeded to form Er2O3 coating layer on large interior surface area of metal pipe using Metal Organic Chemical Vapor Deposition (MOCVD) process. In this work, Er2O3 coating layer of hydrogen penetration control on stainless steel 316 (SUS 316) substrate have been investigated to the effect of hydrogen penetration and using SEM, TEM and SAED patterns. Er2O3 coating layer of before hydrogen penetration was granular structures from SEM observation. Er2O3 coating layer was columnar grains from TEM observation. TEM image and SAED patterns obtained from Er oxide film can be understood that the growth direction of Er2O3 film was [110].
Simulation of Yield Strength in Allvac® 718PlusTM
Authors: Ahmadi M.R. , Whitmore L. , Povoden-Karadeniz E. , Stockinger M. , Falahati A. , Kozeschnik Ernst
Published: May 2014

In the present study, we describe a comprehensive and consistent physical model for the yield strength change in Allvac® 718PlusTM caused by precipitation strengthening. The model incorporates the effect of different shearing and non-shearing mechanisms with respect to atomic continuity between the lattices of precipitates and matrix. We demonstrate that coherency and anti-phase boundary effects are the major strengthening mechanisms in this alloy. The final yield strength of Allvac® 718PlusTM during aging is investigated using the thermo-kinetic software MatCalc. The calculated final yield strength evolution is consistent with experimental results.
Effect of TiO2 Nanotube Arrays on Osseointegration for Dental Implant
Authors: Shim Seong Cheol , Choe Byung Hak , Jang In San , Choi Dong Soon , Lee Jae Kwan , Cha Bong Kuen , Choi Won Youl
Published: May 2014

Dental implant with porous surface has been studied by many researchers because it has a good osseointegration. TiO2 nanotube arrays on the surface of dental implant could provide the porous surface, the space of drug loading, and better biocompatibility than bare surface. To investigate the effects of TiO2 nanotube arrays for dental implant, commercial dental implant was used and its surface was anodized to fabricate TiO2 nanotube arrays. Highly ordered TiO2 nanotube arrays were grown on the surface of dental implant. Ethylene glycol based electrolyte was used in anodic oxidation process. Anodic oxidation voltage and time were 50V and 15 min, respectively. The micro structure was observed by FE-SEM. The diameter and length of TiO2 nanotube arrays were ~60 nm and 10μm, respectively. BMP-2 was loaded in TiO2 nanotube arrays. For in-vivo testing, the dental implant with TiO2 nanotube arrays was applied to rabbit legs for 8 weeks. In dental implant with TiO2 nanotube arrays, good osseointegration properties were observed. TiO2 nanotube arrays fabricated by anodic oxidation will be very useful in the field of bone implants and bone tissue engineering.
Microstructural Evolution of Martensite Phase in Fe-Ni Alloy Depending on Temperature of Tensile Deformation
Authors: Sonoda Takanori , Sato Hisashi , Moritani Tomokazu , Watanabe Yoshimi
Published: May 2014

Martensite (α’) formed in Fe-Ni alloy is mainly separated into four morphologies (thin plate, lenticular, butterfly and lath). The morphology of the α’ depends on its formation temperature because accommodation process for transformation strain in the α’ is changed with temperature. Also, crystal orientation relationship between α’ and austenite (γ) is depended on the morphology of the α’. In this study, temperature dependence of the microstructural evolution of the butterfly-type α’ in Fe-30mass%Ni alloy by tensile deformation is investigated. When the tensile test is performed at room temperature (RT), morphology of the butterfly-type gets close to lath-type α’. On the other hand, the morphology of the butterfly-type α’ is kept under the tensile test at lower temperature. These microstructural changes of the butterfly-type α’ depending on the tensile temperature are discussed in term of the change of the accommodation process for the transformation strain.
Corrosion Behavior of Engineering Materials in Flow Field
Authors: Soya Yuki , Yoshihara Shoichiro , Ohmura Yuki , Mac Donald Bryan J. , Galvin Emmet
Published: May 2014

In this study, the effect of fluid flow rate, surface roughness and strain level on the corrosion behavior of magnesium alloy AZ31 was characterized in a custom test bench. Specimens were prepared by mechanical polishing and subject to flow in a simulated body fluid at 37°C for 24 hrs. Compared to a specimen pre-strain of 0%, mass loss was shown to increase by approximately 6% with a specimen pre-strain of 10%. Similarly, mass loss increased by approximately 13% when the fluid flow rate was increased from 250ml/min to 500ml/min. Surface roughness had a significant influence on corrosion behavior. Compared to a specimen polished with a 1 µm diamond paste, the mass loss for a specimen polished with #600 sandpaper was 28% greater.
Clarification of Extremely High R-Value Mechanism of the Electro-Deposited Pure Iron
Authors: Sugiura Natsuko , Yoshinaga Naoki
Published: May 2014

Electro-deposited pure iron has a very sharp and isotropic <111>//ND fiber texture and a needle shaped grain elongated in the ND. This pure iron exhibits an r-value of over 7, and it is difficult to explain such a high r-value only from the texture. Specific {110} plane slips, which are perpendicular to the sheet surface, exclusively act in this material and this limitation of the active slip system is the main mechanism behind the extraordinarily high r-value. Thus, tensile deformation by this slip system doesn’t require a decrease in thickness. In this study, the mechanism of this slip system limitation is investigated. Because both the {110} slip plane and grain boundary are perpendicular to the sheet surface, the slip plane can easily connect with adjacent grains. This good continuity of slip plane with adjacent grain may have an influence on the choice of slip system.
Application of a Novel Entrainment Defect Model to a High Pressure Die Casting
Authors: Watson Robert , Zeguer Tayeb , Ruffle Simon , Griffiths William D.
Published: May 2014

Aluminium High Pressure Die Castings are economical to produce in high volumes. However, as greater structural demands are placed on such castings, a more detailed understanding is required of the defects which limit their strength. The process is prone to high levels of surface turbulence and fluid break-up, resulting in the entrainment of air into the liquid metal, which may manifest as trapped air porosity or bifilm defects in the finished part. A novel algorithm was developed and integrated into a commercial computational fluid dynamics (CFD) package, to model mould filling, and the formation and transport of such entrainment defects. A commercial High Pressure Die Casting was simulated using this algorithm, to illustrate its application. Castings were also produced, and the results of tensile testing were summarised in the form of Weibull statistics. It was found that where the algorithm predicted a greater quantity of entrained surface film, a reduction in UTS of about 10% was also observed.
Effects of Annealing on Microstructure and Properties of Cu-Nb Wires
Authors: Deng Li Ping , Han Ke , Sun Ze Yuan , Yang Xiao Fang , Liu Qing
Published: May 2014

This paper reports the results of investigation into the effects of annealing on microstructure, hardness, and electrical resistivity of accumulated drawing and bundling (ADB) Cu-Nb wires. Noticeable change took place during annealing. When annealing was conducted at 500 °C, samples showed higher hardness and electrical resistivity in the wires with higher deformation. Furthermore, samples annealed at temperatures above 500 °C showed delay in recovery and recrystallization. At 900 °C, however, the reverse was true, with samples showing lower hardness and resistivity in wire with higher degree of deformation.
Microstructural and Mechanical Characterizations of a Ductile Metastable β Titanium Alloy Subjected to Low Temperature Annealing
Authors: Zhang Jing Yong , Sun Fan , Brozek Cedrik , Nowak Sophie , Prima Frédéric
Published: May 2014

Low temperature thermal treatments, between 423K and 573K, were performed to optimize the mechanical properties of a ductile beta metastable titanium alloy with TRIP and TWIP effects. A set of short-time heat-treatments (STT) were applied at 423K, 473K, 523K, and 573K for 60 and 600s, respectively. The results show that the tensile strength and Vickers hardness increase as the annealing temperature increasing. The sample annealed at 423K for 60s possessed a modest yielding strength (≈566MPa), Vickers hardness (≈327HV) and excellent elongation (≈53%); whereas the sample annealed at 573K for 600s shows a very high yielding strength (≈1256MPa), Vickers hardness (≈441HV) but a small ductility. It is worth noting that the sample annealed at 473K for 60s exhibited the best combination of high strength (close to 1200MPa of true stress) and a stable plastic zone of ɛ=0.4(true strain) with a significant strain hardening effect. It is clarified that both TRIP and TWIP deformation mechanisms are promoted after the heat treatment of 60s at 473K, resulting in good balance among the tensile strength, the ductility and the strain hardening behavior.
Mechanical Properties and Precipitation Behavior of Ti-Mo Microalloyed Medium-Carbon Steel during Ultrafast Cooling Process
Authors: Deng Xiang Tao , Wang Zhao Dong , Misra R.D.K. , Han Jie , Wang Guo Dong
Published: May 2014

We describe here the mechanical property evolution and precipitation hardening behavior under different cooling conditions including ultrafast cooling (UFC) + air cooling process and accelerated cooling (ACC) + air cooling process in a Ti-Mo microalloyed medium carbon steel is described here. The results demonstrate that the cooling procedure after hot rolling has a significant influence on the mechanical properties of the microalloyed steel. The yield strength and tensile strength that were obtained by ultrafast cooling (UFC) + air cooling process were higher than those from accelerated cooling (ACC) + air cooling process, while the elongation was slightly reduced. Microstructural characterization indicated that grain refinement and precipitation hardening were the primary reasons for the increase in strength of the experimental steel. Ultrafast cooling increased the density of dislocations and refined the grain size. Average size of precipitates containing Ti and Mo was 3~6 nm in ultrafast cooling (UFC) + air cooling process, while average precipitate size obtained by accelerated cooling (ACC) + air cooling process was 6~9 nm.

Keywords: Ti-Mo medium-carbon steel; Precipitation; Ultra fast cooling process; accelerated cooling process
The Effect of Fuel Type on Temperature Profile within Pilot-Scale Downdraft-Gasifier for the LPG Replacement in Electricity Production
Authors: Chaijunda Pongdee , Kruehong Chaiyaput , Thabuot Mallika , Waisurasingha Chattichai , Chindaprasirt Prinya
Published: May 2014

This research presents the effect of fuel type on temperature profile within the pyrolysis-, combustion-and reduction-zone of the pilot-scale downdraft gasifier, and the replacement potential of LPG with syngas for electricity production. The experimental results showed that gasification of different fuels have the distinctions of temperature level in each zone. More stable syngas production was obtained either from wood chips (WC) or plastic carrier bag (PCB). In contrast, gasification of aluminum coated plastic bag (ACPB) showed the unsatisfied syngas. From the operation with the dual mode of LPG and syngas for electric production, LPG consumption was reduced about 27.08%, 14.58% and 8.33% when PCB-, WC-and ACPB-syngas were used, respectively.
Numerical Investigation of Airflow Pattern inside Environmental Chamber
Authors: Thongsri Jatuporn , Suksawaeng Wutthinan
Published: May 2014

In industrial hard disk drive research and development laboratories, an environmental chamber is normally used to perform a mechanical verification test of Head Gimbal Assembly (HGA). It is very important to verify that the airflow pattern in the chamber is comparable to that in a real hard disk drive. Hence, we applied a transition shear stress transportation turbulence model (transition SST), one of the robust mathematical models in computer fluid dynamics, to simulate the airflow behavior inside both an environmental chamber and a hard disk drive (HDD). We found that, overall, the two patterns of airflow were not comparable at all. The air velocity vectors around the HGA in VENA were smaller than that in HDD. The reason for this is likely to be that there was more space between the top cover of the chamber and the platter than the space between the top cover of the hard disk drive and its platter.
Simulated Trajectories of Particles and the Number of Particles Trapped by the Circulating Filter in a Hard Disk Drive
Authors: Thongsri Jatuporn , Pongkom Vana
Published: May 2014

The particle trajectories and the number of them trapped by circulating filter of a 2.5 inch dual platter hard disk drive (HDD) were numerically investigated using a transition shear stress transport turbulence model (transition SST). Four head gimbal assemblies (HGAs) were placed at the outer diameter positions where tiny particles of alumina were released. The simulation revealed the results of airflow, particle trajectories and efficiency of a circulating filter. This result can be applied as fundamental information to design HDD layout in order to reduce its contamination.
Keywords: Airflow, Circulating Filter, Hard Disk Drive, Particle Trajectory, Computational Fluid
Dynamics
PV Modules Deterioration with Less than 15 Years Installation in Thailand
Authors: Wiengmoon Buntoon , Kirtikara Krissanapong , Jivacate Chaya , Chenvidhya Dhirayut
Published: May 2014

This paper presents the investigation on deterioration of PV modules installed in Thailand. The modules under this study were dismantled and collected from KMUTT installation in the Buriram province. Modules were same model of modules that were installed over a thousand of solar water pumping systems and battery charging stations by Green E-san project since end of the 1980's and in earlier of 1990's. There are 35 modules, single crystalline silicon sized 47 Wp, in this study that were exposed in the field with less than 15 years. The experiments consist of visual inspection and measurement of performance at standard test condition (STC 1000 W/m2, 25 °C AM1.5) according to IEC61215:2005 standard. It is found that physical deteriorations and power output degradations. The physical deteriorations in this study can be classified delamination on middle cell, delamination on bus bar, delamination of edge cell and discoloration. For power output degradation, there is no module that was degraded less than 20% of nameplate wattage. There are only 8 of 35 modules (~23%) having power output over 50% of power rating.
Differential Evolution Algorithm for Solving a Nonlinear Single Pendulum Problem
Authors: Panagant Natee , Bureerat Sujin
Published: May 2014

A differential evolution (DE) algorithm has been employed to approximate the solution of a nonlinear single pendulum equation. The solution has been approximated as a Fourier series expansion form. Then, weighted-residual and penalty functions are employed to transform the problem into a constrained optimization problem while optimum solutions will be carried out by DE. This paper also studies an effect of a scaling factor of DE to the results. The results reveal that the scaling factor significantly affects the convergent speed and accuracy of DE. Approximate solutions well agree with the exact solutions for the scaling factor being 0.5.
Effects of an Injection Angle of Water Pipes in an Ultrasonic Cleaning Tank on Particle Disposal Capability
Authors: Wongmanee Kitikorn , Bureerat Sujin , Benjapiyaporn Julaporn
Published: May 2014

This paper presents simulation of particle dispersion in an ultrasonic cleaning tank.Contaminants removed from work-pieces by means of ultrasonic waves need to be disposed from the tank during the cleaning process. This is achieved by using water injection from horizontal tubes placed at the bottom inside the tank. It is expected that injection angles could affect the performance of particle disposal. The two-phase flow simulation is adopted to predict disposal capability while the computational fluid dynamic is carried out by means of finite volume analysis. Simulation results of particle dispersion in the tank with various injection angles are conducted, displayed, and concluded.
Laminar Convection Heat Transfer in Square Channel Fitted Diagonally with 45° V-Discrete Baffles
Authors: Tamna Sombat , Poonperm Rachan , Promvonge Pongjet , Thianpong Chinaruk
Published: May 2014

This work presents a numerical investigation of laminar periodic flow and heat transfer in a constant heat flux-surfaced square-channel fitted diagonally with 45° V-discrete baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 200 to 1,200. Effects of different blockage ratios (BR=b/H), BR in range from 0.05-0.2 with pitch ratio of 1.0 on heat transfer and pressure loss in the channel are studied. It is apparent that vortex flows created by the 45° diagonal V-discrete baffle exist and help to induce impinging flows on wall leading to drastic increase in heat transfer rate over the smooth channel. In addition, the increase in the BR results in the rise of Nusselt number and friction factor values. The computational results reveal that the optimum thermal enhancement factor of the 45° V-discrete baffle is about 2.24 at BR=0.2.
Estimation of Smoke Plume Height from Early Burning via Simulation
Authors: Limthavorn Panuphan , Tachajapong Watcharapong
Published: May 2014

At present, the forest fires cause smoke and pollution problem in Chiang Mai that affects human, animal, and ecosystems. Over the past few years, air pollution from forest fire has increased. The resident in northern of Thailand faces problems with air pollution and deforestation. Protecting the forest fires and environmental is the one of top priority in solving this problem in northern of Thailand. Therefore, early burning is one of the solution that has been chosen to used in Chiang Mai forest fire prevention strategies.