bluuebunny/crossref_metadata_2025 huggingface dataset:
Change in Mechanical Strength and Bone Contact Ratio of Beta-Type TNTZ Subjected to Mechanical Surface Modification
Authors: Akahori Toshikazu , Hattori Tomokazu , Fukui Hisao , Niinomi Mitsuo
Published: November 2016

Ti-29Nb-13Ta-4.6Zr (TNTZ), which is one of metastable beta-type Ti alloys, has developed as one of representative biomedical and dental Ti alloys in Japan. TNTZ subjected to solution treatment shows Young’s modulus of 60 GPa, which is close to that of cortical bone. In addition, TNTZ has very low cytotoxicity and good bone biocompatibility as well. Heat treatment like solution treatment and aging (STA) is mainly used for improving the mechanical properties of metastable beta-type Ti alloys because of alpha precipitates, while Young’s modulus also rises drastically. This study was investigated the effects of mechanical surface modifications such as fine particle bombarding (FPB) with steel and hydroxyapatite particles or friction stir processing (FSP) on the mechanical strength of TNTZ in order to maintain low Young’s modulus. The relative bone contact ratios between the cancellous bones of Japanese white rabbits and column-shaped TNTZ subjected to FPB of steel particles were also evaluated. Vickers hardness (HV) of TNTZ subjected to FPB with fine particles of steel and hydroxyapatite particles increased by HV30 to 200 at the edge of the specimen surface to around 100 to 300 mm in depth as compared with that of TNTZ subjected to solution treatment. The hydroxyapatite layer was formed on the specimen surface by FPB with fine particles of hydroxyapatite particles, although the trend was not significant by FPB with steel particles. Furthermore, the fatigue strength in high cycle fatigue region of TNTZ subjected to FPB with steel particles was improved and the fatigue limit showed around 400 MPa, although that of TNTZ subjected to FPB with fine particles of hydroxyapatite particles were around 60 MPa higher than that to TNTZ subjected to solution treatment (230 MPa). TNTZ with a rough surface texture (Ra: 0.65 μm) showed a relative bone contact ratio of more than 80% after undergoing FPB with fine particles of steel particles; this value was significantly higher than that of TNTZ with a surface texture (Ra: 0.07 μm). Lastly, the microstructure of TNTZ subjected to FSP showed the recrystallization area by the frictional heating with very fine equiaxed beta phase with an average grain diameter of 3.0 μm. The change in Vickers hardness of TNTZ subjected to FSP was almost identical to that of Young’s modulus and showed the almost same trend of FPB.
Tensile and Fatigue Properties of Miniature Size Specimens of Sn-5Sb Lead-Free Solder
Authors: Kobayashi Kyosuke , Shohji Ikuo , Hokazono Hiroaki
Published: November 2016

Tensile and low cycle fatigue properties of Sn-5Sb (mass%) solder were investigated with miniature size tensile specimens. The effect of temperature and strain rate on tensile properties and the effect of temperature on low cycle fatigue properties were examined. Tensile strength increases with increasing strain rate regardless of temperature investigated. For elongation, the effect of temperature on it is negligible although it slightly increases with increasing strain rate. The low cycle fatigue life of Sn-5Sb obeys by the Manson-Coffin’s equation. The effect of temperature on the fatigue life is negligible in the temperature range from 25 oC to 150 oC. In the low cycle fatigue test with a high total strain range of 4%, cracking at phase boundary mainly occurs regardless of temperature investigated. In the case of a low total strain range of 0.4%, ductile fracture mainly occurs, and cracking at phase boundary with generation of grooves also occurs at high temperature.
Effect of Sr Addition on the Solidification Structure in Al-6mass%Mg-3mass%Si Alloy
Authors: Yanagihara Emi , Aoshima Goshi , Komura Shota , Saikawa Seiji , Ikeno Susumu
Published: November 2016

Al-Mg-Si system alloy have good strength and high ductility without heat treatment. However, the castability in this alloy is inferior to other aluminum alloy, in particular, hot-tearing is easy to occur during solidification. In our previous study, hot-tearing was not occurred in the case of 0.04%Sr addition to this alloy, because of the remarkable refinement of eutectic Mg2Si phase. In this study, in order to clarify the mechanism of the change of the crystallized eutectic Mg2Si morphology, the effect of Sr addition on the solidification structure in Al-6%Mg-3%Si alloy was investigated. By Sr addition to this alloy, the change of the nucleation mode from homogeneous to heterogeneous was occurred with the temperature drop at the start of eutectic reaction, and the great change of eutectic growth mode from facet to non-facet was thought to be a main reason improving of hot-tearing.
Analysis of Recrystallization Behavior of Hot-Deformed Austenite Reconstructed from EBSD Orientation Maps of Lath Martensite
Authors: Kubota Manabu , Ushioda Kohsaku , Miyamoto Goro , Furuhara Tadashi
Published: November 2016

The recrystallization behavior of hot-deformed austenite of 0.55% C low alloy steels at 900, 850 and 800°C was investigated by a conventional double-hit compression test and a new method which reconstructs the parent austenite orientation map from an EBSD (electron backscattering diffraction) orientation map of daughter lath martensite. The new method can clearly reconstruct the parent austenite structure at high temperature from the daughter lath martensite structure and we can obtain the information on crystal orientation of the work-hardened austenite. It was revealed that recrystallization of austenite at 800 °C is significantly retarded by the addition of 0.1% V. The strong texture of <110> parallel to the compression direction develops just after the hot-deformation, but this texture becomes weaker as the recrystallization progresses. By applying the reconstruction method, it becomes possible to evaluate various phenomena related to the hot-deformation of austenite
Solidification of Al-Pb Alloy under the Effect of Micro-Alloying Element Ti and C
Authors: Sun Qian , Jiang Hong Xiang , Zhao Jiu Zhou
Published: November 2016

Experiments were carried to investigate the effect of TiC on the solidification process and microstructure of Al-Pb alloys. It is demonstrated that TiC particles are effective inoculants for the nucleation of the Pb-rich droplets during cooling an Al-Pb alloy in the miscibility gap. A model describing the kinetic behavior of TiC particles in the melt and the liquid-liquid decomposition of Al-Pb was developed. The dissolution, coarsening and precipitation processes of TiC particles as well as the microstructure evolution during the liquid-liquid phase transformation of an Al-Pb alloy were calculated. The numerical results indicate that what determines the refinement efficiency of TiC particles on the Pb-rich droplets/particles is the number density of TiC particles in the melt cooled to the binodal line temperature of the Al-Pb alloy. If the number density of TiC particles in the melt before the beginning of the liquid-liquid decomposition is high enough, the addition of TiC causes a refinement of the Pb-rich droplets/particles and promotes the formation of Al-Pb alloys with a well dispersed microstructure.
Aging Property of AZ91D Magnesium Alloy Screw Thread-Rolled at Room Temperature Using Extrusion-Torsion Simultaneous Processing
Authors: Furui Mitsuaki , Sakashita Shouyou , Suzuki Shougo , Aida Tetsuo , Ishisaka Yuusuke , Yamamoto Masayuki , Ohta Masayuki
Published: November 2016

We have proposed a new extrusion process functionally combined with torsion. Extrusion-torsion simultaneous processing is a very attractive technique for fabricating a rod-shape material with high strength and excellent workability. To improve the hardness, the aging treatment was performed with AZ91D magnesium alloy screw thread-rolled at room temperature using extrusion-torsion simultaneous processing. The distribution of hardness from the tip to center in as thread-rolled screw was modified to uniform distribution by the isothermal aging treatment at 423 K for 460.8 ks. The peak hardness was not depended on the working temperature and rotation speed during extrusion-torsion simultaneous processing. β-Mg17Al12 precipitates are obviously grown in as peak-aged condition comparing with as thread-rolled condition.
Simultaneous Precipitation and Recrystallization during Hot Deformation of Ti, Nb and V Microalloyed Steel
Authors: Buken Heinrich , Sherstnev Pavel , Kozeschnik Ernst
Published: November 2016

Recrystallization is a major means for controlling the grain size of steel during hot deformation. Usually, small grain sizes deliver superior mechanical properties. To aid the grain size controlling effect of recrystallization, small precipitates of carbo-nitride particles can be utilized to hinder the movement of grain boundaries. Interestingly, these particles are not only effective during grain growth, but also during recrystallization. In the present work, a recently developed state-parameter based model is introduced that is capable of describing both, the individual processes of static recrystallization, dynamic and static recovery and precipitation as well as the mutual interaction of these mechanisms in the course of elevated temperature processing. The evolution of state parameters within the model is discussed and the simulation results are compared to experimental information. Within our approach, a vast amount of experimental data for microalloyed steel is reproduced on basis of a single set of input parameters
Stereolithographic Additive Manufacturing of Ceramic Components by Using Nanoparticle Paste Feeding
Authors: Kirihara Soshu
Published: November 2016

Titania and alumina photonic crystals were fabricated by using stereolithographic additive manufacturing to control electromagnetic waves in terahertz frequency. Micro ceramic patterns were designed spatially by graphic software. Photosensitive liquid resin with ceramic particles were spread onto a grass substrate by mechanical knife edge, and two dimensional (2D) images were drawn using fine pattern exposing to create a cross sectional solid layer. After stacking these layers, the obtained three dimensional (3D) structures of composite precursors are dewaxed and sintered.
Development of High-Performing Extruded Magnesium Alloy
Authors: Lim Hyun Kyu , Kim Young Kyun , Kim Bong Hwan , Kim Dae Kuen , Yoon Young Ok , Kim Shae K.
Published: November 2016

To develop high-performing extruded magnesium alloys, we had investigated the effect of zinc into Mg-5Gd-2Y-xZn-0.7Ca (x = 1, 2, 3, and 4) alloys. With increasing of zinc content up to 3 wt.%, the volume fraction of LPSO phases and strength increased, while the volume fraction of LPSO and strength rapidly decreased when zinc content was 4 wt.% in Mg-5Gd-2Y-xZn-0.7Ca alloys. Ignition temperature and corrosion rate were directly proportional to the increase of zinc content in this study. The optimum zinc content was 2 wt.% in Mg-5Gd-2Y-xZn-0.7Ca alloys and VWZO52207 alloy exhibited high strengths (TYS: 407 MPa and UTS: 424 MPa), adequate elongation (6.9 %), and high ignition temperature (934 oC).
Phase Stability Study of the Shape Memory Alloy CuAl-X (X: Be, Zn, Ti, Ni, Ag and Au) by Ab Initio Calculations
Authors: Boudalia Nassim , Raulot Jean Marc , Patoor Etienne , Esling Claude
Published: November 2016

Shape memory alloys (SMA) have been at the forefront of research in recent years. They have been used for a wide variety of applications in various fields. This work presents a brief study at the atomic scale of Cu-Al based Shape Memory Alloys. Using first-principles Density Functional Theory (DFT) method, the stability of different austenitic and martensitic phases of Cu3Al, the effect of intrinsic vacancies, the doping effect by an element X (X = Be, Zn, Ti, Ni, Ag and Au) have been studied.
Effect of Misch Metal Addition on Thermal Conductivities and Mechanical Properties of Mg-4Zn-0.5Ca Alloys
Authors: Oh Gun Young , Yoon Young Ok , Kim Shae K. , Lim Hyun Kyu , Kim Young Jig
Published: November 2016

The thermal conductivities of quaternary Mg-Zn-Ca-MM alloys have been investigated by evaluating the effect of MM on Mg-4Zn-0.5Ca alloys, with an emphasis to develop a new Mg alloy without compromising thermal conductivity, process-ability and mechanical property. As a result, the thermal conductivity of 0.5 wt.% MM-added Mg-Zn-Ca alloy was almost same as that of MM-free Mg-Zn-Ca alloy. However, with further increasing MM contents, thermal conductivities of MM-added alloys decreased. The tensile yield strength was improved with increasing MM contents. In addition, the average spiral flow lengths of Mg-Zn-Ca-xMM alloys were almost same levels with Mg-Zn-Ca alloy.
Evolution of Microstructure and Microhardness in Ti-15Mo β-Ti Alloy Prepared by High Pressure Torsion
Authors: Václavová Kristína , Stráský Josef , Veselý Jozef , Gatina Svetlana , Polyakova Veronika , Semenova Irina , Janeček Miloš
Published: November 2016

The main aim of this study is to analyze the effect of the severe plastic deformation (SPD) on the mechanical properties and defect structure of metastable beta Ti alloys. Experiments were performed on two different β-Ti alloys: Ti-15Mo and Ti-6.8Mo-4.5Fe-1.5Al which were subjected to severe plastic deformation (SPD) by high pressure torsion (HPT). The increase of hardness with increasing equivalent strain was determined by microhardness mapping. Dislocation density was studied by advanced techniques of positron annihilation spectroscopy (PAS). Microhardness and dislocation density increases with increasing equivalent strain inserted by severe plastic deformation.
Microstructure of AZCa912 Continuous Casting Bar after Hot Compression
Authors: Watazu Akira , Omura Naoki , Miwa Kenji
Published: November 2016

AZCa912, 8.8mass%Al-0.68mass%Zn-0.25mass%Mn-1.9mass%Ca-Bal.Mg, continuous casting bars with 50 mm in diameter were formed by a direct chill continuous casting method. AZCa912 alloy is a noncombustible magnesium alloy. The surfaces of the bars had excellent metallic luster. A dendrite structure with a DAS of around 11-23 μm and grain sizes of about 200 μm was observed. Samples with almost the same grain size and different DAS were measured at hot compression test at 250-350°C, 0.01-1/s. Crack on the side surfaces of the samples were not formed by compression at 350°C, 0.01-0.1/s. All samples had an unchanged casting structure after hot pressing, and the percent of the structure remaining unchanged decreased with low-temperature compression and wide DAS.
Microstructural Investigation of Oxynitrocarburized Components Processed at Different Temperatures
Authors: Caliari Daniele , Timelli Giulio , Salata Tiziano , Maestri Sergio , Cavagnini Giuseppe
Published: November 2016

Gas nitrocarburizing combined with a post-oxidation treatment is an interesting industrial process developed in order to improve wear and corrosion resistance of low alloyed steel components. In the present work, the microstructure resulting by a thermochemical treatment, which comprises nitriding, nitrocarburizing and post-oxidation stages, applied to an industrial 16MnCr5 component, has been studied. Both the nitriding and nitrocarburizing temperatures were systematically changed in order to study the resulting phases in the compound layer. The depth of the compound layer have been measured by optical microscopy to evaluate the effect due to the variations in the process variables during the nitrocarburizing process. Moreover, the microstructure has been investigated by means of a scanning electron microscope equipped with a electron backscatter diffraction detector in order to assess the amount and the distribution of Fe-N-C phases. A temperature increase from 510 up to 550°C during the nitriding process inside a NH3 atmosphere induces a higher fraction of ε-Fe2-3(C,N) compounds. On the contrary, nitrocarburizing at 600°C instead of 580°C under a gaseous mix of NH3 (50%), CO2 and N2 favors a greater amount of γ'-Fe4(C,N) nitrides. A greater amount of porosity in the outer part of the compound layer favors a thicker oxide film obtainable with the post-oxidation process.
Optimal Deformation Hardening in Lead Base Anodes for Copper Electrowinning for an Appropiate Working Life
Authors: Camurri Carlos , Carrasco Claudia , Maril Yazmín
Published: November 2016

The lead base anodes (Pb-0.07% Ca-1.3% Sn) of 6 mm thick have limited working life due to their loss of thickness and corrosion during the electrowinning process. If this loss of thickness is combined with a low yield stress of the anodes, these are much more likely to suffer premature deformations and distortions in cells. The aim of this study is to optimize the deformation hardening of the anodes, so as to achieve the best combination of yield stress and corrosion resistance to increase their working life. To achieve this the aged anodes were cold rolled to different area reductions from the standard 50% to 75%. To each one of these rolled anodes its yield stress was determined by plane compression tests, their grain sizes was measured by means of optical microscopy and their corrosion rate was determined by coulomb metric assays in a cell using an electrolyte concentration of sulfuric acid of 180 g/l and a oxidation current density of 300 A/m2.It was found that the maximum yield stress of the anodes increases from 58 MPa to 64 MPa when cold reduction goes up from 50% and reach 70% . Regarding the corrosion rate, the maximum and minimum values were 0.33 mm/ year and 0.30 mm / year, i.e., with no significant differences between the different rolled anodes. Based on the above results it is concluded that an increase in the working life of the anodes is obtained simply by giving them greater cold rolling deformation from the current 50% to 70% of area reduction.
Dynamic Transformation during Plate and Strip Rolling
Authors: Jonas John Joseph , Aranas Jr. Clodualdo , Rodrigues Samuel F. , Jung In Ho
Published: November 2016

Torsion simulations were carried out of both plate (long interpass times) and strip (short interpass times) rolling. Both isothermal and continuous cooling conditions were employed. The dynamic transformation of austenite to ferrite was observed under all conditions and at all temperatures within the austenite phase field. About 8 to 10 volume percent ferrite was formed in a given pass, leading to about 50 - 70 % ferrite at the end of selected simulations. During the interpass intervals, some retransformation to austenite took place, the amount of which increased with holding time and temperature and decreased with the addition of alloying elements. It is shown that the driving force for the transformation is the softening associated with the replacement of work-hardened austenite grains by the softer alpha phase. The implications with respect to rolling load (i.e. mean flow stress) are also discussed.
Influence of Dynamic Strain Ageing and Long Term Ageing on Deformation and Fracture Behaviors of Alloy 617
Authors: Chai Guo Cai , Calmunger Mattias , Johansson Sten , Moverare Johan , Odqvist Joakim
Published: November 2016

Influences of dynamic strain ageing and long term ageing on deformation, damage and fracture behaviors of Alloy 617 material have been studied. Dynamic strain ageing can occur in this alloy at temperature from 400 to 700°C, which leads to a strain hardening and also an increase in fracture strain due to plastic deformation caused by twinning. Long term ageing at 700°C for up to 20 000 hours can cause different precipitation such as γ ́, M6C (Mo-rich) and M23C6 (Cr-rich) carbides. These carbides are both inter-and intra-granular particles. The long term ageing reduces the fracture toughness of the material, but the alloy can still have rather high impact toughness and fracture toughness even with an ageing at 700°C for 20 000 hour. The mechanisms have been studied using electron backscatter detection and electron channeling contrast imaging. It shows that besides dislocation slip, twinning is another main deformation mechanism in these aged Alloy 617 materials. At the crack front, plenty of micro or nanotwins can be observed. The formation of these twins leads to a high ductility and toughness which is a new observation or a new concept for this type of material.
Development and Industrial Applying on Rolling Mill 5000 of the Model of Austenite Grain Size Evolution in Nb-Microalloyed Steels
Authors: Chastukhin A.V. , Ringinen D.A. , Golovin S.V. , Efron L.I.
Published: November 2016

In this research evolution of austenite grain size in Nb-microalloyed steels X65÷X120 grades during slab reheating and roughing rolling was studied. A mathematical model has been development to obtain the target temperature and soaking time in furnace, which ensure a uniform austenite structure and maximum possible dissolution of the carbonitride particles prior to roughing rolling. The Hot Rolling Recrystallization Model (HRRM) has also development to predict the austenite microstructure evolution during roughing rolling. The model is based on empirical equations and organized following a tree-structure. A validation of the model has been carried out in the laboratory by multipass compression tests. The models jointly have been used to create new strategies of processing technology of rolled plates on rolling mill 5000 for the South Stream pipeline. The industrial application has confirmed a great benefit of the models in point of cold resistance of rolled plates.
The Observation of Austenite to Ferrite Martensitic Transformation in an Fe-Mn-Al Austenitic Steel after Cooling from High Temperature
Authors: Cheng Wei Chun , Lee Kun Hsien , Lin Shu Mao , Chien Shao Yu
Published: November 2016

Fe-Mn-Al steels with low density have the potential to substitute for TRIP (transformation induced plasticity) steels. For the development of Fe-Mn-Al TRIP steels, phase transformations play an important role. Our methods of studying the phase transformations of the Fe-16.7 Mn-3.4 Al (wt%) austenitic steel include heating and cooling. We have studied the martensitic transformation of the ternary Fe-Mn-Al steel. Single austenite phase is the equilibrium phase at 1373 K, and dual phases of ferrite and austenite are stable at low temperatures. It is noteworthy that lath martensite forms in the prior austenite grains after cooling from 1373 K via quenching, air-cooling, and/or furnace-cooling. The crystal structure of the martensite belongs to body-centered cubic. The formation mechanism of the ferritic martensite is different from the traditional martensite in steels. Ferrite is the stable phase at low temperature.
Mechanical Analyses of Welding in Practical Field
Authors: Choi Kwang , An Gyubaek
Published: November 2016

In order to produce reliable welded product quality accumulated experiments are basic requirements.But nowadays production conditions are changing and quality requirements are becoming more and more severe. In these cases using achievement of computer in hardware and software can be a nice tool for improving welding production in efficiency and time saving. In this study three samples are shown in order to show the improvement in welding products with the aid of computer. (Repair welding, Tack welding and High frequency electric resistance welding)
Mechanical Properties of Fine-Grained and Ultrafine-Grained Ti-6Al-4V with Equiaxed and Bimodal Microstructures
Authors: Chong Yan , Tsuji Nobuhiro
Published: November 2016

With the purpose of fabricating equiaxed and bimodal Ti-6Al-4V alloy with different grain/primary α (αp) sizes, thermomechanical processing and additional annealing were carried out on samples with martensite initial microstructure. Deformation at 700°C with a strain rate of 0.01s-1 to a true strain of 0.8 could effectively break the martensite initial microstructure into ultrafine-grained (UFG) equiaxed microstructure (mean grain size of 0.51μm) with reasonable uniformity. Subsequent annealing at 930°C with different periods were conducted to change the equiaxed microstructure into bimodal microstructures. The holing time proved to be more critical than heating rate for determining the αp size. An UFG bimodal Ti-6Al-4V with the average αp size of 0.55μm was successfully obtained for the first time by annealing the UFG equiaxed Ti-6Al-4V at 930°C for 2 seconds. The mechanical properties of the equiaxed and bimodal Ti-6Al-4V with different grain/αp sizes were evaluated by tensile tests at room temperature. The bimodal Ti-6Al-4V showed superior balance between strength and uniform elongation than that of the equiaxed Ti-6Al-4V. Moreover, the uniform elongation in the bimodal Ti-6Al-4V was nearly unaffected by reduction of the αp size.
Analysis of Pre-Strain in a Hybrid Forming Process Including Stretch and Incremental Sheet Forming
Authors: Lora F.A. , Silva B.C.S. , Coelho R.S. , Schaeffer L.
Published: November 2016

The conventional sheet metal forming processes, such as deep drawing and stretch forming, are used to produce large batches of parts, however they incur in higher initial manufacturing costs attributed to the use of a large amount of tooling. The application of conventional and incremental forming processes combined in the same metal sheet is called hybrid forming. This hybrid process is enacted by pre-forming the sheet through the stretch forming process followed by the final manufacture using the incremental process. The objective of this work is to analyze the influence of the pre-strain imposed during the conventional process on the DC04 steel relative to the maximum strain obtained. A numerical simulation was used to define the parameters for the conventional process and to evaluate the experimental results. The higher major true strains are inversely proportional to the pre-strain in both experimental and simulated results.
Modeling the Microstructural and Yield Strength Evolution of an Age-Hardenable Al Alloy for High Temperature Applications
Authors: Colombo Marco , Gariboldi Elisabetta , Bassani Paola , Albu Mihaela , Hofer Ferdinand
Published: November 2016

The mechanical properties of Al alloys are strongly affected by their microstructure: the size and shape of precipitates, their homogeneous distribution and their coherency with the matrix are of primary importance for an effective strengthening of the alloys at room and elevated temperatures.
Physically-based models are powerful tools to predict the influence of the mentioned parameters on the mechanical properties of the alloy after age hardening, and also to predict the effect of high temperature service conditions on microstructure evolution.
Scope of this work is to model the dimensional kinetic evolution of plate shaped precipitates of an Al-based alloy during aging and after different overaging times at elevated temperature, and use these results to estimate the alloy yield strength. The alloy strengthening response is due to three terms, linearly summed: the intrinsic strength of Aluminum, the contribution from solute in solid solution and the contribution arising from precipitates.
The consistency of the model is verified with experimental data obtained from a 2014 Al alloy.
Laser-Induced Surface Texturing of Metal or Organic Substrates for Structural Adhesive Bonding
Authors: Costil Sophie , Kromer Robin , Gojon Sébastien , Aubignat Emilie , Verdy Christophe , Liao Han Lin , Langlade Cécile
Published: November 2016

Laser-matter interaction is commonly described regarding three main factors: laser beam, materials and environment. Conversion of absorbed energy via collision process into heat is the most important effect that occurs during laser interaction. Short-pulsed laser beam induces fast transition from the overheated liquid to a mixture of vapor and drops which allows the ablation of micrometric layers. Specific patterns can then be achieved using scanning and automation technology also called laser texturing.
New materials with specific properties such as endurance life and/or lower environmental impact attract emerging technologies such as thermal spraying. However, adhesive bond strengths have to be high enough to play a key role in surface properties. A clean surface to enhance mechanical interlocking is a key element. Mechanical and physico-chemical bond strength for thick coatings elaborated by thermal spray process can then be developed using laser.
The aim of the present paper is to show the potential of such emerging treatments through new results using various thermal spray processes (thermal spraying as well as cold spraying). Metal or organic materials were investigated implementing various powders.
Nanooxides Derived from Hydrotalcites as Catalysts for Dry Methane Reforming Reaction - Effect of [Ni(EDTA)]2- Adsorption Time
Authors: Dębek Radosław , Motak Monika , Galvez Maria Elena , Grzybek Teresa , da Costa Patrick
Published: November 2016

Mg/Al hydrotalcite-like materials containing ceria were synthesized as catalysts precursors for the reaction of dry methane reforming. The nickel species were introduced into the catalytic systems via adsorption from aqueous solution of [Ni (EDTA)]2- complexes for 4 and 24h and the effect of adsorption time on the catalytic properties of obtained materials was evaluated. The mixed nanooxides were obtained by thermal decomposition of hydrotalcite-like materials at 550°C for 4h and the catalysts were subsequently characterized by XRD, elemental analysis, H2-TPR and low temperature N2 sorption techniques. The adsorption duration of [Ni (EDTA)]2- influenced the properties of the prepared materials, such as textural properties, nickel crystallite size, and thus their catalytic activity in the reaction of dry reforming of methane. The sample which underwent adsorption for 24h turned out to be the most active in DRM reaction. However, over this catalyst RWGS reaction was well developed, which caused the excess of CO in the products of the reaction and faster deactivation of the catalyst.
Dynamic Piezoelectric Behavior of Lithium Niobate at High Temperature
Authors: de Castilla Hector , Bélanger Pierre , Zednik Ricardo J.
Published: November 2016

High temperature piezoelectric materials have numerous potential applications, including high temperature ultrasound NDT, MEMS, sensors, or actuators. However, conventional piezoelectric materials are unsuitable for operation above 400°C. Lithium niobate (LiNbO3) is a promising candidate because of its very high Curie temperature (approximately 1210°C) and reasonable piezoelectric coefficients. However, the piezoelectric properties are not sufficiently understood, partly due to the difficulties in characterizing this behavior at high temperature. Degradation mechanisms well below the Curie temperature, suspected to include phase transformations, oxygen loss, and excessive ionic conductivity, further deteriorate this property. In order to better understand these physical mechanisms, electrochemical impedance spectroscopy (EIS) is used to characterize monocrystalline LiNbO3 from room temperature to 500°C, with excitations from 20 Hz to 20 MHz. An equivalent circuit model analysis, including resonant frequencies, is developed to investigate the temperature dependence of the piezoelectric behavior, as well as the mechanical elasticity and damping. Numerical values extracted from this analysis allows for numerical simulations to model device behavior.
Photonic Application of Diatom Frustules
Authors: de Matteis Fabio , Prosposito Paolo , Francini Roberto , de Angelis Roberta , Mochi Federico , Melino Sonia , Congestri Roberta , Bruno Laura , Casalboni Mauro
Published: November 2016

Diatoms are unicellular aquatic microalgae possessing amazing self-assembled ordered micro-and nanoporous hierarchical silica cell walls called frustules. The quasi-periodic and highly regular pore patterns on the diatom surface are very attractive for applications based on optical and photonic properties of materials. The present contribution reports on pioneering research aimed at explore the multiple scattering and localization of light shown by diatom frustules in order to amplify their photoluminescence in a random laser (RL), as this technology is highly attractive for medical diagnostics and other advanced applications. RL is a special type of laser in which the optical feedback is due to light scattering in an amplifying medium instead of a conventional optical cavity. We have studied a set of selected frustules with different shapes and pore patterns, obtained from diatom cultivation in large scale photobioreactors, for comparative analysis of their random lasing effect in the bioscaffold soaked with organic dyes having luminescence in the visible range. Taking advantage from a multidisciplinary approach combining expertise from biology, physics and materials sciences, relying on high-resolution instrumentation and advanced algal cultivation equipment the results about random laser emission in the composite material were obtained. This will allow going ahead in the research aimed to the application to photonic devices in the field of medicine and medical diagnostic.
Microstructural Evolution and Mechanical Behavior of Low Density Fe-Mn-Al-C Steels with High Stacking Fault Energy
Authors: Ding H. , Wu Z.Q. , Han D. , Zan N. , Bleck Wolfgang
Published: November 2016

The microstructures and the mechanical properties of two Fe-26Mn-xAl-1C steels with 8 and 10 % Al have been investigated at different strain rates. The results show that Fe-26Mn-10Al-1C steel possesses higher strength and at the same time higher ductility than Fe-26Mn-8Al-1C steel at both low and high strain rates. The strengths of the steels increase and ductility declines slightly with increasing strain rate. These observations can be attributed to the different strain hardening mechanisms acting at different strain rates. Planar slip occurs and microbands form duringthe steady state stage, whereas deformation twinning occurs in the final stage ofdeformation. The higher strain hardening at high strain rates are due to the strong increase in the twinning propensity. The strain hardening at high strain rates also depends on the adiabatic heating, causing a competition between softening and strain hardening.
Nanocomposites Consisting of Carbon Nanotubes and Nanoparticles of Noble Metals
Authors: Dobrzańska-Danikiewicz A.D. , Cichocki D. , Łukowiec D.
Published: November 2016

In the framework of the made researches nanocomposite of CNT-NPs type (Carbon Nanotube-Nanoparticles) consisting of multiwalled carbon nanotubes coated by rhodium nanoparticles and/or palladium using the two-step indirect method: chemical reduction have been produced. In the researches high-quality multi-walled carbon nanotubes MWCNTs with a length of 100 to 500 nm and a diameter of 8 to 20 nm previously obtained in the catalytic-chemical vapour deposition CCVD have been used. Nanotubes produced within the framework of own researches contain minor amounts of metallic impurities and amorphous carbon deposits. In order to deposit the noble metal nanoparticles on the surface of carbon nanotubes functionalization of multi-walled carbon nanotubes in a mixture of H2SO4 and HNO3 acids have been used. The prepared material has been subjected chemical reduction using noble metal precursors (RhCI3, PdCl2). The characterization of the produced material including the examination of the structure, morphology, chemical composition and evaluation of the size and distribution of rhodium and/or palladium nanoparticles on the surface of carbon nanotubes has been performed using: scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS). The produced nanomaterials may be used as the active layer of sensors of chemical/biological agents.
An Experimental Investigation of the Size Effects in Forming Processes of High-Purity Thin Metallic Sheets
Authors: Dubos Pierre Antoine , Fleurier Gwendoline , Hug Eric
Published: November 2016

Miniaturization of small metallic systems can lead to a softening of the mechanical behavior due to the reduction of scale. Size effects have been considerably studied recently for materials with various crystallographic structures. Under tensile conditions, thin specimen exhibit softer mechanical properties when the number of grains across thickness is lower than a critical number and this modification appears above a critical strain level. In this work, stamping tests were performed on five hundred micrometers in thickness sheets of hexagonal closed-packed cobalt. The results are compared with those obtained for face centered cubic copper and nickel. The influence of thickness over grain size ratio was studied for several proportional loadings linked to forming processes. Complex loadings were applied with 20 mm hemispherical punch and strain paths were checked with a 3D video extensometer. Hill criterion was systematically used to take into account the anisotropy of the samples. Our results revealed that the critical strain level for which the size effects appears is strongly sensitive to the stress triaxiality which, in turn, is closely dependent to the loading path.
Machinability of an Experimental Graphitised Carbon Steel
Authors: Inam Aqil , Edmonds David
Published: November 2016

The machinability of an experimental medium-carbon steel with a composition designed to promote rapid graphitisation during a high temperature anneal has been studied. The goal has been to explore alternative routes to a competitive free-cutting composition enabling less expensive steelmaking, manufacturing and recycling. Three starting microstructures prior to annealing have been considered; martensite, bainite and ferrite/pearlite. The microstructures and graphite dispersions formed have been characterised by optical and electron microscopy and the performance of the steel during machining compared with commercial free-cutting steel grades. A bench-top drill rig and metallographic techniques were used to evaluate relative machinability parameters, including surface roughness, tool wear and chip morphology. Thus it proved possible to rank the experimental steel graphitised from the three starting microstructural conditions and also against the commercial free-cutting steels.
Development of Armor High Strength Steel (HSS) Martensitic Plates for Troops Carriers
Authors: El-Bitar Taher , El-Shenawy Eman , El-Meligy Maha , Almosilhy Almosilhy , Dawood Nader
Published: November 2016

The present article is dealing with the conditioning of martensitic steel plates for armoring troops carriers. The steel alloy was processed into ingots. The ingots were hot flat rolled to 80 mm, followed by rolling to 6 mm.
Specimens for detection of the critical transformation temperatures were taken. The Ac1, Ac3, Ms and Mf temperatures were detected as 716, 835, 356 and 218 °C respectively.
The 80mm microstructure contains plate martensite colonies, while the 6mm plates reveal complete plate martensitic structure. Both cases contain embedded carbides.
Heat treatment cycles were proposed for enhancing the ballistic resistance. A treatment was consisting of austentizing at 910 °C for 20 min., followed by water quenching. This process revealed fully fine lath martensitic packets. Tempering was done on the quenched as well as on rolled plates.
Tempering at 350°C, causes dissociation of some martensite, and encourages migration of the entrapped carbon atoms forming carbide aggregates embedded between martensite plates packets. Tempering at 250°C for 20 min., relieves quenching induced stresses and reveals a lath martensitic structure with a small fraction of rosette like carbides. The process enhances elongation from 3% to 11.35%. The microstructure of as-rolled tempered plates at 300 oC for 20-30 minutes contains a thin ferrite layer on the boundaries surrounding the martensite packets, and few fractions of cotton wool shape carbides between the martensite packets. The treatment cycle improves the mechanical properties.
Both treatments, at 250 and 300 oC, show successful ballistic resistance plates against shooting by 3 bullets.
Evolution of Microstructure, Phase Composition and Hardness in 316L Stainless Steel Processed by High-Pressure Torsion
Authors: El-Tahawy Moustafa , Gubicza Jenő , Huang Yi , Choi Hye Lim , Choe Hee Man , Lábár János L. , Langdon Terence G.
Published: November 2016

The evolution of phase composition, microstructure and hardness in 316L austenitic stainless steel processed by high-pressure torsion (HPT) was studied up to 20 turns. It was revealed that simultaneous grain refinement and phase transformation occur during HPT-processing. The γ-austenite in the initial material transformed gradually to ɛ-and α’-martensites due to deformation. After 20 turns of HPT the main phase was α’-martensite. The initial grain size of ~42 μm was refined to ~48 nm while the dislocation density increased to ~143 × 1014 m-2 in the α’-martensite phase at the disk periphery processed by 20 turns. The microstructure and hardness along the disk radius became more homogeneous with increasing numbers of turns. An approximately homogeneous hardness distribution with a saturation value of ~6140 MPa was achieved in 20 turns.
Crystal Structure and Microstructure of Martensite in Ni-Mn-In Alloys and the Behavior of Variant Rearrangement under Uniaxial Loading
Authors: Yan Hai Le , Zhang Yu Dong , Li Zon Bin , Esling Claude , Zhao Xiang , Zuo Liang
Published: November 2016

In the present work, the crystal structure and microstructure of martensite in Ni-Mn-In alloys and the variant rearrangement behavior under the external mechanical loading were investigated. Results show that the martensite has an incommensurate 6M modulated structure (I2/m (α0γ)00) with the modulation wave vector q = 0.3437c*. Microstructure of martensite is in plate shape and self-organized with four orientation variants that are alternately distributed and related in either type-I, or type-II or compound twin relation. The variant interfaces are in coincidence with their corresponding twinning plane and then should be considered coherent. Under the uniaxial compression, the loading located in the common positive Schmid factor zone of the three types of detwinning systems might be favorable to obtain the single variant state. This study is expected to offer a fundamental information of crystal structure, microstructures and variant rearrangement behaviors in Ni-Mn-In alloys, so as to understand the underlying mechanisms of their multifunctional magneto-responsive properties.
Revision of ISO 27306 for CTOD Toughness Correction for Constraint Loss
Authors: Minami Fumiyoshi , Ohata Mitsuru , Takashima Yasuhito
Published: November 2016

As the result of the international standardization work in Japanese IST project, ISO 27306 were published in 2009 for correction of CTOD fracture toughness for constraint loss in steel components. ISO 27306 employs an equivalent CTOD ratio based on the Weibull stress criterion, which leads to more accurate fracture assessment than the conventional fracture mechanics assessment. On the occasion of the 1st periodical review, the revision of ISO 27306 has been proposed from Japan. This paper describes the key contents of the new ISO 27306. A case study is included on the fracture assessment of a wide plate component according to FAD (failure assessment diagram) approach specified in BS 7910:2013.
Integrated Defect Classification in Manufacturing of Carbon Fibre Reinforced Thermoplastic Polymer Matrix Composites
Authors: Fischlschweiger Michael , Stock Alexander , Thurmeier Markus
Published: November 2016

Thermoplastic polymer matrix composites with continuous carbon fibre reinforcements are of crucial relevance in automotive industry. The mix of high performance and cost effective manufacturing makes them attractive for high volume production. However, it could be shown that production integrated end of line quality control is of strong importance to ensure continuous and traceable part quality. Besides, typical non destructive testing method specifications, higher production volumes additionally require short testing times. Herein, the application of active thermography as end of line quality control in composite production is evaluated and compared with results obtained by X-ray radiometry. It could be revealed that transient pulse phase thermography is a powerful tool to analyse part quality of continuous thermoplastic polymer matrix composites in short testing times.
Components of a Heart Catheter System for High Risk Patients
Authors: Gatomski Gregor , Nguyen Hong Nhung , Quadrini Fabrizio , Foitzik Andreas H.
Published: November 2016

As late as fifteen years ago the intracardiac catheter was only used for diagnostic purposes. Since then it has also been established as a therapeutic method. The latest studies have shown that the reduction in convalescence that normally follows a catheter-interventional implantation of aortic valves by transcatheter aortic valve implantation is less significant in comparison to that of a cardiac surgery operation. It is expected that such minimal-invasive technologies will grow to a great extent, also helping to reduce socio-economic costs for the European health care system. Patients of higher ages with acquired cardiac defects or children with congenital cardiac defects of heart valves, especially of the pulmonary valve, are currently the main target groups. We present an alternative and optimized mechanism for stent placement and similar therapeutical interventions. This project focuses on the manipulation unit and tube system. It carries out a highly precise and repeatable linear motion. Ergonomic requirements are taken into account. Furthermore a possibility to support the linear motion by minimal strain is presented. The product is designed for disposable applications but is generally also suitable for long-term applications.
The Quantification of Galling in Forming Operations of Hot Dip Galvanized Sheet Metal under Laboratory Conditions
Authors: Giedenbacher Jochen , Raab Anna Elisabeth , Walch Christian , Huskic Aziz
Published: November 2016

In the sheet metal forming industry, tools are subject to mechanical, thermal, chemical and tribological loads. One of the major problems in forming operations of hot-dip galvanized sheet metal is galling (build-up of zinc flakes on the tool). This phenomenon develops gradually as an adhesion on the tool surface. The adhesive wear leads to high rejection and reworking costs for large car body forming tools. Due to economic aspects and the easy castability, the forming tools are made of cast iron. These materials tend to high adhesive wear. The aim of this project is to find a three-dimensional surface parameter, which describes a tribologically advantageous surface of forming tools in order to reduce galling. An additional objective is to optimize tool materials, heat treatment and surface coating. The evaluation of galling under laboratory conditions is based on strip drawing tests. The characterization of tool materials was executed for grey cast iron (EN-GJL-200/250) and nodular cast iron (EN-GJS-700). Investigations demonstrate that the processing methods and test parameters like sliding speed and temperature have a significant influence on galling. Three-dimensional surface parameters have also shown an effect on galling.