bluuebunny/crossref_metadata_2025 huggingface dataset:
Creation of Harmonic Structure Materials with Outstanding Mechanical Properties
Authors: Ameyama Kei , Hiroshi Fujiwara
Published: January 2012

Conventional material developments have emphasized ultrafine grain refinement and homogenization. However, “nano- and homo-” materials do not usually satisfy the need to be both strong but ductile, which are of course rather contradictory characteristics. To solve such a problem, we have succeeded in designing a “Harmonic Structure Material” that is both a “nano- and harmonic” material which has overcome that antinomy through use of one of the non-equilibrium powder metallurgy (PM) processes called the severe plastic deformation (SPD) PM process. In the present study, pure Ti, Ti-6Al-4V alloy and SUS316L stainless steel powders are subjected to mechanical milling (MM) for various periods of time. The MM powders have two kinds of microstructure, which can be controlled by the MM conditions. They include ultra fine and coarse grain structures known as “shell” and “core”, respectively. Subsequently, these MM powders are sintered using conventional sintering processes. The sintered materials with the shell and the core have a network structure of continuously connected shells, which we refer to as a harmonic structure. The sintered materials with the harmonic structure simultaneously demonstrate both high strength and elongation. These outstanding mechanical properties are influenced by harmonic structure characteristics such as shell and core grain sizes, shell area fraction and shell network size. Thus, the harmonic structure can be considered as a remarkable design for improving the mechanical properties of materials
Low Velocity Surface Fracture Patterns in Brittle Material: A Newly Evidenced Mechanical Instability
Authors: Hattali M.L. , Barés J. , Ponson L. , Bonamy D.
Published: January 2012

The occurrence of various instabilities at very high speed is well known to occur in brittle fracture and significant advances have recently been obtained in the understanding of their origin. On the other hand, low speed brittle crack propagation under pure tension loading (mode I) is usually thought to yield smooth crack surfaces. The experimental investigation reported here questions this statement. Steady cracks were driven in brittle glassy polymers (PolyMethyl Methacrylate - PMMA) using a wedge-splitting geometry over a wide range of low velocities (10-9-10-1 m/s). Three distinct patterns can be observed on the post-mortem fracture surfaces as crack velocity decreases: perfectly smooth at the highest speed, regularly fragmented at intermediate speed and macroscopically rough at the lowest speed. The transition between the two latter is reminiscent of chaotic transition. ahattali.lamine@gmail.com, bjonathan.bares@cea.fr, cponson@caltech.edu, ddaniel.bonamy@cea.fr,
Influence of Microstructure on Damage in Advanced High Strength Steels
Authors: Hisker Frank , Thiessen Richard , Heller Thomas
Published: January 2012

AHSS (Advanced High Strength Steels) combine high strength and good ductility. Their outstanding forming and work-hardening behavior predestines these steels for fabrication of strength relevant structural elements and automobile body parts. To characterize a material, not only tensile, but also hole-expansion and bending behavior are important and help predict the stretch-flange-formability. In this study, detailed analyses of the correlation between these three tests and the damage mechanisms during forming have been performed for selected steels. The results show that for AHSS one should differentiate between “local” and “global” failure. Furthermore, not only are certain materials more sensitive to local or global damage, but also various testing methods tend to provoke either local or global damage. Tensile testing provokes global failure whereas hole-expansion tends to induce local failure. A specimen fails during bending with a mixture of local and global modes. These failure modes are strongly attributed to the microstructure. DP-steels yield high elongation during tensile testing and poorer hole-expansion values. High-resolution EBSD has revealed that the microstructure of DP-steels is sensitive to localized damage, which is compensated by work-hardening around damaged regions and thus shifts the loading to un-hardened regions. This makes DP-microstructures well-suited to tensile loading but sensitive to hole-expansion. CP-steels of comparable strength show poorer tensile elongation and higher hole-expansion ratios due to a microstructure which is not sensitive to localized failure (but has limited capacity for work-hardening). The failure mode in TRIP-steels exhibits a similar character as in DP-steels, but only after the martensitic transformation of retained austenite.
Effect of Die Temperature on Tensile Property of Rheocast Phosphor Bronze
Authors: Kose Takahisa , Uetani Yasuhiro , Nakajima Katsuyuki , Matsuda Kenji , Ikeno Susumu
Published: January 2012

Semi-solid slurry of phosphor bronze with fine solid granules for rheocasting was tried to make by passing the low-superheat melt through an opening between a rotating regular octagonal rotor and a circumscribed chill block. The effect of rotational speed on the structure of a solidified small ingot was mainly investigated. The ingot structures were changed from the dendrite of rotor-free condition to the rosette at the rotational speed of 50rpm, and the granular with a mean size of about 50μm at higher than150rpm. The slurries made at 150rpm were rheocast to a cylindrical shape cavity within a die kept at different temperatures from 573 to 1173K by the use of a high pressure casting machine. Microstructures of rheocast cylindrical shape products were granular at the die temperatures lower than 773K and changed to grained one as like recrystallized at higher than 973K. Together with the microstructure change, poor tensile ductility less than 3% at the lowest die temperature was improved up to about 60% at 973K.
Effect of Pulsed Electric Current Treatment on the Corrosion and Strength of Reinforcing Steel
Authors: Kruszka Leopold , Babutsky Anatoli , Chrysanthou Andreas , Tan Chu En
Published: January 2012

The study was carried out in order to evaluate the effect of the pulsed electric current (PEC) treatment on the corrosion as well as on static strength of Polish reinforcing steel. As-received St3SX was used for investigations. Two kinds of specimens were manufactured by turning from 20 mm diameter re-bars: cylinders of 10 mm diameter and 28 mm length for corrosion tests and standard cylindrical specimens of 6 mm diameter and 30 mm length for static tension tests. Corrosion tests was performed according to the ASTM B117-97 standard. As-received steel tensile specimens and the specimens after PEC treatment were tested using a servo-hydraulic universal testing machine at the strain rate of 10-2 s-1.
Intergranular Cracking in Alloy 690 with Nb, Mo, and Hf Additions: In Situ SEM High Temperature Deformation Study
Authors: Unfried Jimy S. , Ramirez Antonio Jose
Published: January 2012

The microstructure behavior during high temperature deformation of Ni-base alloys based on alloy 690 modified with Nb, Mo, and Hf additions were studied. Optical and electron microscopy were used to characterize these materials and the results were compared with Calphad-based modeling results. The alloys behavior was studied between 500 and 1000 °C using an in-situ high temperature deformation test. The role of precipitates on the grain boundary morphology and their effect on grain boundary sliding and the mechanism of ductility-dip cracking are discussed. Both, undulated grain boundaries and primary intra-granular precipitates improved the alloy DDC resistance.
Effects of Cleavage Triggers and Constraint on Brittle Fracture in Steel Weld Heat Affected Zone
Authors: Shimada Yusuke , Kayamori Yoichi , Inoue Takehiro , Tagawa Tetsuya
Published: January 2012

Cleavage fracture in steel is usually evaluated by using the stress criterion. However, some researchers indicated the necessity of strain in the stress criterion according to the cleavage fracture test results of steel base metal. If so, the cleavage fracture criterion should be also applicable to steel welded joints. In this study, cleavage fracture tests, SEM fracture surface observations and FEA were conducted using the smooth and notched round bar tensile specimens of the simulated HAZ microstructure of JIS SM490A. Cleavage trigger types did not influence the cleavage fracture properties of the specimens obviously. FEA results suggested that the critical condition of cleavage fracture initiation was associated not only with stress but also with strain.
Equivalent CTOD Concept for Correction of CTOD Toughness for Constraint Loss in Steel Weld Components
Authors: Minami Fumiyoshi
Published: January 2012

This paper presents a new fracture assessment method, IST method developed as ISO 27306. The IST method implements an equivalent CTOD ratio, β, for the CTOD toughness correction for constraint loss in structural components. Using β, the standard fracture toughness specimen and structural components are linked at the same level of the Weibull stress. This paper extends the equivalent CTOD concept to weld components. Effects of the weld strength mismatch and residual stress on β are discussed. It is shown on the failure assessment diagram (FAD) that the CTOD toughness correction with β leads to accurate fracture assessments of weld panels, whereas the conventional procedure gives much conservative results.
Tensile Fracture Behavior of Friction Stir Processed Al-7Si-0.3Mg Cast Alloy
Authors: Chen Zhanwen , Abraham Francis , Walker Joshua
Published: January 2012

Elimination of porosity and refinement of the normally coarse cast microstructure ofaluminium cast alloys by the intensive plastic deformation during friction stir processing (FSP) iswell known. However less is known about the mechanical behavior of the FS processed regionwhich contains zone/pass boundaries and macro/microstructure segregations. In the present study ofFS processed cast Al-7Si-0.3Mg alloy, microstructures featuring the deformed α-Al, fragmented Siparticles and their distribution in the processed region were related to the fracture paths duringtensile testing. It has been found that under the condition of a high rotation speed and minimum pinoverlap there is a strong upward flow of deformed cast material in thermomechanial affected zone.The arrays of Si particles in that flow have provided favorable paths for crack propagation duringtensile testing. As a result, tensile elongation and thus UTS values are low. The mechanism of thatupward flow and FSP conditions for reducing the flow and thus for improving properties of theprocessed region are discussed.
Phenomena Leading to a Modification of the Nano-Sized Structure during Resistance Upset Welding of ODS Steel Cladding
Authors: Corpace Fabien , Monnier A. , Poulon Quintin A. , Manaud J P.
Published: January 2012

ODS steels (Oxide Dispersion Strengthened) are candidate materials for fuel cladding in Sodium Fast Reactors (SFR). These materials have good mechanical properties at high temperature due to a dispersion of nanometer-sized oxides into the matrix. Previous studies have shown that melting can induce a decrease of the mechanical properties at high temperatures due to modifications of the nanometer-sized oxide dispersion. Therefore the fusion welding techniques are not recommended and the solid state boundings has to be evaluated. This study is focused on resistance upset welding. Welding experiments and numerical simulations are coupled. The numerical simulation is developed in order to have a better understanding of the thermal and the mechanical phenomena occurring during the welding process. The simulation shows that the welding steps can be divided in two stages. First, the temperature of the contact between pieces increases. Second, the heat generation is mainly located in the cladding leading to the collapse and forging the pieces. The microstructural observations confirm that the major deformation is located in the cladding. Oxide dispersion modification and dynamical recrystallisation has been found for welds achieved with a non optimized process parameter set. The deformation and the temperature seem to be of prime importance in the modification of the oxide dispersion.
Material Flow in Aluminum Friction Stir Welds
Authors: Fonda Richard W. , Reynolds Anthony P. , Feng C.R. , Knipling Keith E. , Rowenhorst David J.
Published: January 2012

A detailed examination of the texture evolution occurring within a friction stir weld inAA2195 reveals features that are not consistent with current models of material ow in frictionstir welds. While the deposited weld is dominated by a B ideal shear texture component, thistexture periodically alternates with a B texture, indicating a reversal in the sense of the sheardeformation. In addition, the observed rotation of the orientation of these shear textures, andtheir replacement by a distinct, new shear texture orientation to correct for the misorientationthat develops, reveals a heretofore unobserved characteristic of friction stir welds that providesfurther details about material ow during friction stir welding.
Friction-Stir Welding of High-Softening-Temperature Materials Using Cobalt-Based Alloy Tool
Authors: Park Seung Hwan C. , Hirano Satoshi , Imano Shinya , Sato Yutaka S. , Kokawa Hiroyuki , Omori Toshihiro , Ishida Kiyohito
Published: January 2012

The authors have developed a new friction-stir welding (FSW) tool that enables to weld high-softening-temperature materials (HSTMs), such as steels, titanium and zirconium alloys. The new tool is made of a Co-based heat-resistant alloy strengthened by precipitating intermetallics, Co3(Al,W), with a L12 structure at high temperatures. The Co-based alloy tool exhibits yield strengths higher than 500 MPa at 1000 deg C, so it might have a great potential as a tool material for FSW of HSTMs. In this study, the feasibility of using the Co-based alloy tool with various HSTMs was examined. Changes in the tool shape during FSW and the weld appearances produced with the Co-based alloy tool will be briefly shown.
Electrochemical Deposition of the Ca-P Coatings on the Porous Nanocrystalline Ti-6Al-4V Alloy
Authors: Adamek G. , Jakubowicz Jarosław
Published: January 2012

The formation mechanism of the Ca–P coating on the porous nanocrystalline Ti-6Al-4V alloy is presented. The Ca–P compounds were cathodically deposited at different potential (from –0.5 to –10 V vs. open circuit potential), using a solution mixture of Ca (NO3)2+ (NH4)2HPO4+ HCl. Depending of the deposition potential, the atomic ratio of Ca/P in deposits is in the range from 0.25 to 1.71, which indicates that the coating composition corresponds in some cases to hydroxyapatite. The Ca–P particles penetrate preferentially the pores inside, which improve bonding of the bioceramic layer to the metallic substrate. Increasing the cathodic deposition potential results in changes of the Ca–P morphology from thin porous, through cracked up to thick 90 μm continous coating. The porosity of the Ca–P decreases with increasing cathodic deposition potential. It is proposed the electric field enhancement mechanism of the electrolytic ions flow and Ca–P growth on the surface irregularities, such as pores and surrounding hillocks.
Microbial Aspects in Corrosion Studies of Stainless Steels
Authors: Michalska Joanna
Published: January 2012

Microbially influenced corrosion (MIC) has been focusing increasing attention from different research areas in the last years, as an answer to the demand of wide variety of industries and degradation cases. The difficulty in reaching an adequate understanding of corrosion processes induced by microorganisms has result in cross-fertilization of ideas between researchers from different disciplines like microbiology, electrochemistry, metallurgy and materials engineering. Different MIC mechanisms can be simultaneously or alternately occuring on various materials, where a complex boundary layer of corrosion products, bacterial cells and other environmental factors are present on the surface. The paper discusses new aspects of MIC mechanisms induced by sulphate reducing bacteria species, taking into consideration modern techniques and new approaches in the study. Practical cases concerning microbial risks, failures illustrate the complexity of this phenomena: from local corrosion problems through stress corrosion cracking and hydrogen damage. The role of microstructure and chemical composition of materials is also highlited as a key factor in microbial damaging. In addition to this, the principal morphologies of attack and cracking are described.
Surface Modification of Pure Titanium by TiB Precipitation
Authors: Miklaszewski A. , Jurczyk M.U. , Jurczyk M.
Published: January 2012

Titanium and its alloys are common in medical implant applications because of their desirable properties, such as relatively low Young’s modulus, good fatigue strength, corrosion resistance, biocompatibility as well as formability and machinability. However, these materials cannot meet all of the clinical requirements. Current research focuses on improving not only the mechanical performance but mostly the biocompatibility of Ti-based systems through variations in alloy composition and surface treatment. One of the methods that allows the change of biological properties of Ti surface is the modification of its chemical composition. In this work plasma surface modification approach was used to improve mechanical properties by synthesis of composite layer structure on a pure titanium surface. The study aims at development of TiB precipitation dispersed uniformly at α-Ti matrix by plasma melting of Ti-2 wt% and Ti-10 wt% B alloy powders composition. Grain size of precursor powders obtained by mechanical alloying method and its homogenization can control the porosity and boron agglomeration tendency of the synthesized layers. Plasma procedure was taken under argon and helium inert atmosphere and surface was obtained by single passage of plasma pillar upon the prepared surface. The Vickers microhardness of obtained surface reached nearly 850HV, which was much higher compared with initial sample of the pure titanium substrate of 160HV. The surface corrosion resistance in 0.9% NaCl solution was nearly the same as for pure titanium, showing stable behaviour of created oxide layer, with no negative effect of dual phase microstructure.In vitrobiocompatibility test in static condition was performed. All samples showed good cell growth. Our studies suggests that chemical composition of modified titanium surface by TiB precipitation by plasma alloying process has no negative effect on cytocompatibility.
Formation of High Corrosion Resistant Nanotubular Layers on Titanium Alloy Ti13Nb13Zr
Authors: Ossowska A. , Zieliński A. , Supernak M.
Published: January 2012

This paper presents results of oxidation tests and corrosion investigations of titanium alloy Ti13Nb13Zr performed at different conditions. The oxide layers have been formed by electrochemical method in 2M H3PO4 + 0.3% HF solution for 30 min. and 1 h at 20 V constant voltage. The corrosion tests have been made by potentiodynamic method in Ringer`s solution at pH ranged between 3 and 7. It has been shown that the nanooxide films, which improve corrosion resistance of titanium alloy Ti13Nb13Zr even if acidic environment, have appeared.
Electrochemical Properties of Ni-Cr and Co-Cr Alloys Used in Prosthodontics
Authors: Pochrząst M. , Marciniak Jan , Wróbel K. , Bączkowski Bohdan
Published: January 2012

The aim of the work was evaluation of electrochemical properties of Co-based alloys (Remanium GM 800+ and Biosil F) and Ni-based alloys (Heraenium NA and Remanium G-Soft) commonly used on frameworks for porcelain faced cast partial dentures. First stage of the work was evaluation of surface roughness by means of direct linear contact measurement (SURTRONIC 3+ profiler, Taylor/Hobson) of samples after casting and surface treatment. Electrochemical properties of surface were assessed by means of potentiodynamic and impedance methods. In potentiodynamic tests, in order to evaluate pitting corrosion resistance of the analyzed alloys, anodic polarization curves were recorded. The VoltaLab® PGP 201 system was applied in corrosion tests. Moreover, in order to evaluate structure and properties of the surface layer the electrochemical impedance spectroscopy (EIS) was applied. Selection of this method enabled to determine the impedance of the material – surface layer – solution interface with the use of approximation of impedance data by means of equivalent electric circuit model. The EIS tests were carried out with the use of the AutoLab PGSTAT 302N system equipped with the FRA2 Faraday impedance module. Electrochemical tests were carried out in artificial saliva at the temperature of 37°C and pH = 7,0±0,1.
Formation of Porous Structure of the Metallic Materials Used on Bone Implants
Authors: Seramak Tomasz , Serbiński Waldemar , Zieliński Andrzej
Published: January 2012

Research on improvement of structure and fabrication methods of the bone implants are carried out for many years. Research are aimed to shape the structures, that will have a Young's modulus value similar to the value of the human bones Young's modulus. Depending on the porosity, Young’s moduli can even be tailored to match the modulus of bone closer than solid metals can, thus reducing the problems associated with stress shielding of a human bones. The designed structure should also be characterized by a high abrasion and corrosion resistance to and allow bone ingrowth in the implant material to make the best bone-implant fixation. For this purpose, implants should have a porous structure with an appropriate pore size and with open-cell porosity. Material for bone implants must also have a high biocompatibility and bioactivity. Following these requirements, the metallic porous materials appear to be the most suitable material for bone implants.
In this paper a various methods of a porous materials fabrication for bone implants are listed. It was shown that titanium and its alloys (e.g. Ti6Al4V or Ti13Nb13Zr) are widely used as biomaterials for implants. Research in order to increase their wear and corrosion resistance and to improve their biocompatibility and bioactivity are still carried out. One of the most effective methods of manufacturing the porous materials is a powder metallurgy (PM).
In this paper the results of research under shaping the structure of the porous titanium alloy Ti13Nb13Zr are also presented. As a manufacturing method of the porous material from the investigated and mentioned above Ti alloy, the powder metallurgy (PM) was choosen - with and without the use of a space holders. Method of fabrication a spherical powder from the aforementioned Ti alloy and results of its morphology research are discussed. The applied powder compaction method (with use and without use of space holders) and the influence of a sintering process on the final microstructure morphology of porous material obtained from Ti13Nb13Zr alloy are also presented and discussed.
Experimental Investigations of MREs Behavior under the Cyclic Load
Authors: Slawinski Grzegorz , Miedzińska Danuta , Niezgoda Tadeusz , Boczkowska Anna
Published: January 2012

In the paper the experimental results of the dynamic tests of the MRE samples cured without and under magnetic field are presented and compared. The samples (55 mm diameter and 70 mm) were made of the polyurethane elastomer PU 70/30 with the admixture of the ferromagnetic particles (in this case – carbonyl iron spheres with the diameter of about 9 μm). The samples with ferromagnetic particles were cured without as well as under the external, parallel to the vertical axis of the sample, magnetic field of the 300 mT intensity. The experiments were carried out on the materials testing machine for static and dynamic loads INSTRON 8802. The machine was additionally equipped with the measurement head of 4kN scope and the magnetic coil that produces the magnetic field of the intensity up to 500 mT. Cycled load was applied to the MRE samples. In the case of the dynamic tests the sinusoid cyclic variable load was used. The applied load frequency was 1 Hz in each presented test. The samples were cyclically compressed of the 10, 15, 20 and 25 % of their height. On the base of the obtained results the force maximum values and the dumping coefficient (the energy dissipation coefficient) in each dynamic tests were calculated. The hysteresis loops in the load – displacement charts that were observed during the cyclic tests. The influence of the internal structure of the researched material on its strength behaviour is taken into consideration.
Oxidation Time Influence on the Structure of the Cobalt Base Clad Layer and Scale Morphology
Authors: Smolenska Hanna
Published: January 2012

The influence of oxidation time on the microstructure and mechanical property, especially on the hardness, and of Co-base alloy coatings were investigated. Coatings were manufactured by PTA cladding. The cobalt alloy was exposed to temperature 800°C in air for 1, 22 and 200 hours. As a result of oxidation treatment the scale layers were formed and changes in microstructure was observed. Also changes in hardness were noticed.
Optimization of Self-Organized TiO2 Nanotube Geometry on Ti and Ti Alloys Using Fuzzy Logic Reasoning
Authors: Sobieszczyk Sylwia
Published: January 2012

The geometry of self-organized TiO2nanotubes, obtained by electrochemical anodization, has been determined by using fuzzy reasoning approach. The efficiency of TiO2nanotubular layer in biomedical applications depends on geometry and available surface area of nanotubes, which can be determined by their diameter and length. The structure of nanotubes depends on processing parameters of electrochemical anodization, like applied potential, anodization time, and pH of electrolyte. A proposed method showed the possibility of estimation and optimization the nanotubular architecture on Ti and Ti alloys by choosing the appropriate processing parameters based on representative experimental data. A fuzzy reasoning approach was utilized by using Matlab Software.
Corrosion of Ni-Al and Ni-Al-Al2O3 Flame Sprayed Coatings of „CastoDyn 8000" System in 0.01 M H2SO4 and 3.5% NaCl Solutions
Authors: Starosta Robert
Published: January 2012

In the paper researches results of corrosion properties of Ni-Al alloy and Ni-Al-Al2O3 composite coatings were presented. Coatings were obtained by flame spraying of "Casto-Dyn 8000" torch. During coatings flame spraying of torch was used a small distance from the substrate. Instead of commonly used spray distance 150 mm, 100 mm was used. The studies in 0.01 M H2SO4 and 3.5% NaCl (artificial seawater) environments were realized. Evaluated coatings are more corrosion resistant in the 3.5% NaCl environment than in the 0.01 M H2SO4. Corrosion current density for alloy coatings in artificial seawater was 20 μA/cm2 and 223 μA/cm2 in an acidic environment. The value of corrosion potential in an environment of 3.5% NaCl is about 200 mV lower than in 0.01 M H2SO4. Composite coatings Ni-Al-Al2O3 were characterized by a lower corrosion current densities and increased resistance than Ni-Al coatings in acidic environment. The presence of alumina in the coating matrix caused increased corrosion current density in sea water environment.
The Effect of Welding Conditions on Diffusible Hydrogen Content in Deposited Metal
Authors: Świerczyńska Aleksandra , Fydrych Dariusz , Łabanowski Jerzy
Published: January 2012

The primary limitation of weldability of high strength low alloy steel is susceptibility to cold cracking. The important reason of the formation of cold cracks, besides forming brittle structure and residual stresses, is the presence of diffusible hydrogen in welded joint. The most effective methods reducing the susceptibility to cold cracking are connected with decreasing the amount of potential hydrogen. This process may be carried out in technological (drying welding filler materials, preheating components) or in a metallurgical way (filler metals with austenitic structure, adding rare-earths elements to filler metals as traps for hydrogen atoms in steel). The possibility to minimize the amount of diffusible hydrogen by changing the welding parameters seems to be particularly interesting.
The article presents the results of a literature survey and preliminary tests which set out effects of welding conditions on the amount of diffusible hydrogen in deposited metal. Experiments were conducted by using rutile coated electrodes which generate high contents of diffusible hydrogen in deposited metal. The amount of diffusible hydrogen was determined by a glycerin test.
Eleven factors were considered: the electrode angle, the grinding of sample, the preheat temperature, the polarity of welding current, the welding current, the welding – cooling time, the electrode usage, the time of welding, the thickness of specimen, the welding – measurement time and thickness of electrode coating. All factors were optimized using a Plackett-Burman design to get the most relevant variables. The results of the preliminary tests indicate that appropriate choice of welding parameters may considerably reduce diffusible hydrogen in deposited metal. However, the range of parameters is limited by the necessity of providing stability of the welding process and obtaining required properties of the welded joint.
Cavitation Erosion Resistance of Austenitic Stainless Steel after Glow-Discharge Nitriding Process
Authors: Szkodo Marek , Sitko Artur , Gazda Maria
Published: January 2012

This paper presents investigation of cavitation erosion resistance of nitrided austenitic stainless steel X5CrNi18-10. The diffusion layers were produced by using different parameters of reactive atmosphere (N2:H2). The microstructure, chemical composition and phase identification of the modified layer were examined using scanning electron microscopy, glow-discharge optical emission spectrometer and X-ray diffractometry, respectively. Cavitation erosion resistance of produced surface layers was investigated in a rotating disc facility. As a property characterizing the cavitation erosion resistance of manufactured surface layers were proposed incubation period and mass loss after 330 min of cavitation test. It was found that cavitation erosion resistance of modified surface layers is lower than reference material (not treated X5CrNi18-10 stainless steel).
Materials Design for the Titanium Scaffold Based Implant
Authors: Zieliński A. , Sobieszczyk Sylwia , Serbiński Waldemar , Seramak Tomasz , Ossowska A.
Published: January 2012

The main objective of here presented research is a design the scaffold/porous titanium (Ti) alloy based composite material demonstrating better biocompatibility, longer lifetime and bioactivity behaviour for load-bearing implants. The development of such material is proposed by making a number of consecutive tasks. Modelling the mechanical, biomechanical and biological behavior of porous titanium structure and an elaboration of results is performed by mathematical methods, including FEM and fuzzy logic. The development of selected Ti-13Zr-Nb alloy with designed porosity and no harmful effects is made by powder metallurgy (PM) with and without space holders, and by rapid prototyping with an use of selective laser melting (SLM). The development of an oxidation technology resulting in high corrosion resistance and bioactivity is carried out by electrochemical oxidation, gaseous oxidation and chemical oxidation, and their combination. The HA depositon is made by electrochemical and chemical (alternate immersion) methods. The core material is designed as a combination of natural polymer and bioceramics in order to allow slow dissolution followed by stepwise growth of bone tissue and angiogenesis, preventing local inflammation processes, and sustaining the mechanical strength close to that of non-porous material.
Experimental and Quantum Chemical Study of Quinone Derivatives as Inhibitors of Corrosion and Hydrogen Absorption by Steel
Authors: Teryusheva S.A. , Beloglazov G.S. , Beloglazov S.M.
Published: January 2012

Hydroquinone derivatives are studied as inhibitors of microbiological corrosion and hydrogen absorption by mild steel in water salt media that supports development of sulfate reducing bacteria (SRB). The chosen composition of the media is close to sea water containing biogenic H2S. Н2S content, bacterial titer in corrosive media, its pH, Redox potential Eh, and φ of steel together with the quantity of hydrogen absorbed by surface steel sub-layers, were measured. Protective action against corrosion achieved by the best compounds studied, reached the values of 65…84%, while against hydrogen absorption by steel samples − 60…72%. The presence of the studied derivatives of hydroquinone at concentration C= 5 mMoldm–3 resulted in the decrease of SRB cell count at the rate of 48…84%, the suppression rate being at the values of 29…57%.
Prevention to Hydrogen Degradation of Steel
Authors: Cwiek Janusz
Published: January 2012

Purpose of this paper is presentation of forms of hydrogen degradation in steel along with pointing out methods for hydrogen degradation prevention. The paper outlines influence of nitrided layer on 34CrAlNi7-10 steel to its susceptibility to hydrogen degradation. Investigation was carried out with the use of slow strain tensile rate test (SSRT). Fracture surfaces after SSRT test were examined with scanning electron microscope (SEM) to reveal a mode and mechanism of cracking.
Effect of the Ceramic Dispersion in the Nickel Matrix Composite Coatings on Corrosion Properties after Plastic Working
Authors: Dyl Tomasz Cyryl , Starosta Robert
Published: January 2012

Coatings of metal and ceramic composite were applied on the steel specimens using the subsonic process of flame spraying. The specimens were then subjected to both cold and hot plastic working by rolling and also cold pressing by the hydraulic press. Plastic working is an alternative to machining, as the method of finishing of coats applied by flame spraying. The article presents the findings of the research into the possibility of using plastic working (hot and cold rolling and pressing) to obtain the corrosion properties of the flame sprayed Ni-Al alloy coatings and Ni-Al-Al2O3composite coatings. The alloy coatings had a single-phase structure, of the maximum 10% aluminium solubility in the crystal lattice of nickel, whereas in the composite coatings the volume content of non-metallic material Al2O3was 15% and 30 %. After finishing the adhesion reduction, cracks on the surface and cross-sections of coatings was not observed. The largest value of strain hardening of alloy coating Ni-5%Al was stated after pressing. The composite coatings obtain by flame spraying be characterized by big surface roughness (Ra= 13.3 µm). The plastic working caused decrease surface roughness. Minimum value of Raparameter was observed after hot rolling. It was found that maximal roughness was presented after pressing. The corrosion tests were performed in 0.01 M H2SO4solution by potentiokinetic technique. The article presents the effect of dispersion phase of Al2O3on corrosion properties of composite coatings on the nickel base. The corrosion rate was dependent on method of plastic working. The increasing drafts resulted in rise corrosion current density and decrease in value of corrosion potential.
Application of EIS to Study the Corrosion Resistance of Passivated NiTi Shape Memory Alloy in Simulated Body Fluid
Authors: Freitag Marlena , Łosiewicz B. , Goryczka Tomasz , Lelątko Józef
Published: January 2012

The NiTi shape memory alloy passivated for 90 min by autoclaving has been studied towards corrosion performance in the Tyrode’s simulated body fluid using open circuit potential and EIS measurements. The surface morphology and thickness of the oxide layer was determined by XRR. The HREM was used to observe the cross-section of the thin foil and to confirm the amorphous state of the TiO2layer and its thickness. Electrochemical measurements revealed a good corrosion resistance at the beginning of long-term (20 days) immersion. It was found that with the increase of immersion time, the corrosion resistance of the surface deteriorated after nearly 1 day of immersion due to occurence of pitting corrosion. The EIS method was used to detailed study on the electrolyte | passive layer interfacial properties. Equivalent electrical circuit for the pitting corrosion on the passivated NiTi alloy has been applied.
Quality Investigation of Au Nanoarrays for Biosensing Application
Authors: Grochowska K. , Sliwinski G.
Published: January 2012

The properties and ultrafast dephasing time of the Au nanoparticle structures produced for application in biosensors are investigated in dependence on their preparation conditions. The nanostructures are produced from thin Au films (10-20 nm) sputtered on SiO2 glass and annealed by pulsed (6 ns) laser radiation at 266 nm and at fluencies in the range of 10-412 mJ/cm2. The SEM inspection reveals nearly homogeneously distributed, spherical gold particles. Their initial size distribution in the range of 20-60 nm broadens towards larger particle diameters with prolonged irradiation. This is accompanied by an increase of the uncovered surface of the glass substrate and no particle removal is observed. In the absorbance spectra of the nanostructures the broad peak centered at 545-550 nm is ascribed to resonant absorption of surface plasmons. The peak position, halfwidth and intensity depend on the shape, size and size distribution of the nanostructured particles in agreement with literature. From peak intensities of the Raman spectra recorded in the range of 300 – 1800 cm-1 for the structures covered with Rhodamine 6G the relative signal enhancement by factor between 20 and 600 for individual peaks is estimated. Results confirm that the obtained structures can be applied for SERS measurements and sensing. The dephasing times estimated from homogeneous contribution of the absorbance linewidth range from 2.2 to 4.5 fs and correspond to particle diameters of 20-60 nm. It is shown that the dephasing rate 1/T2 can be tailored for particular sensor application by selection of the substrate preparation conditions.
High Temperature Mechanical Spectrum and Interstitial Oxygen in YBaCuFeO5+δ
Authors: Yuan Y.H. , Ying X.N. , Zhu J.S.
Published: January 2012

Double perovskite oxide YBaCuFeO5+δ samples (labeled as “as-prepared”) were sintered by a solid-state reaction technique. Mechanical spectra of as-prepared sample were measured under vacuum condition from room temperature up to 720K by the reed vibration method. In the first heating run, two internal friction peaks were observed around 380 and 620K (labeled as P1 and P2, respectively) in YBaCuFeO5+δ. In the subsequent cooling run, both of them disappeared and a small step-like decrease of the internal friction around 500K was found. This step-like change was reproduced in the following thermal cycles. Thermogravimetric analysis (TGA) was also performed in order to monitor the oxygen content of the sample. It showed that the interstitial oxygen concentration decreased in the first heating run. The interstitial oxygen relaxation is suggested to be the origin of P1 peak. In dielectric measurements, a dielectric loss peak appeared around the temperature of the P2 internal friction peak and the peak temperature was independent on the measuring frequency. It is expected that P2 is associated with some kind of transitions of the interstitial oxygen. Further mechanical loss measurement of the annealed sample and scanning electron microscopy characterizing the as-prepared and annealed samples, provided more information on the interstitial oxygen in YBaCuFeO5+δ samples.
Relaxation Model of Lithium Ions in the Garnet-Like Li5La3Bi2O12Lithium-Ion Conductor
Authors: Gao Y.X. , Zhuang Zhong , Lu H. , Wang X.P. , Fang Qian Feng
Published: January 2012

The relaxation mechanism of lithium ions in Li5La3Bi2O12 electrolyte was investigated by internal friction (IF) method. A prominent relaxation-type IF peak was observed. From the shift of peak position with frequency, the activation energy of E=1.0-1.1 eV and the pre-exponential factor of relaxation time in the order of τ0 =10-25 ~10-18 s were obtained if one assumes a distributed Debye relaxation process. These values of relaxation parameters strongly suggest the existence of interaction between the relaxation species (here lithium ions or vacancies). Basing on the coupling model, the values of E and τ0 were determined as 0.5-0.6 eV and 10-17 ~ 10-15 s, which still deviated from the typical values for point defect relaxation. A new phenomenological model was used to describe the relaxation process, and the values of E and τ0 were determined as 0.46 eV and 3.6×10-14 s, which is in agreement with the typical values for point defect relaxation.
Temperature Dependence of the Flow Stress of Body-Centered-Cubic Metals
Authors: Konstantinović Milan J.
Published: January 2012

By comparing the properties of dislocation-related relaxation processes in internal friction spectra and the tensile data of various iron alloys, we found that the temperature dependence of the flow stress is governed by the total distribution of the activation energies of dislocation motion. The derived model explains the origin of an anomalous temperature dependence of the flow stress in thermally aged Fe-1%Cu alloys, and Fe-x%Cr alloys as a function of Cr concentration, as well as the non-uniform temperature dependence of the flow stress in pure Fe.
Low Frequency Relaxation Effect Observed in Al-Mg Alloy
Authors: Benyahia N. , Gerland Michel , Belamri C. , Rivière Andre
Published: January 2012

Al-12 wt% Mg alloys have been studied by isothermal mechanical spectroscopy. The samples were quenched then annealed at various temperatures. Experiments were performed in a very large frequency range (10-4Hz – 50 Hz) between room and solidus temperatures. For each temperature of measurement, experiment started after complete microstructure stabilization of the sample and therefore the transient effects due for instance to β (( and β′ precipitation were not observed. Nevertheless, a new relaxation effect was obtained in the reversion temperature range. This effect is not thermally activated. It is maximal at about 0.1 Hz and increases with the temperature of measurement. It completely disappears after annealing at solid solution temperature and successive slow cooling and therefore is linked to the β precipitates. This effect is interpreted as a phase transformation at the precipitate surface induced by the applied stress.
Elasticity, Anelasticity and Yield Strength of Al-Si Alloys Obtained by Directional Crystallization
Authors: Nikanorov S.P. , Kardashev B.K. , Korchunov B.N. , Osipov V.N.
Published: January 2012

Acoustic measurements of Young’s modulus and internal friction at frequencies of longitudinal vibrations of about 100 kHz were made in the (5×10-7 to 2×10-4) vibration strain amplitude range for Al-Si alloys. Quasi-static bending stress-strain diagrams were studied as well. The samples of the alloy were prepared using a directional crystallization by Stepanov’s method. The compositions varied from 8 to 25 wt.%Si. The micro-plastic deformation of the materials (acoustic experiments) is explained by dislocation motion in grains of α solid solution. The micro-plastic yield stress has a minimum near the eutectic composition; the flow stress of plastic bending increases smoothly when the Si content increases.
Amplitude Dependent Internal Friction of Magnesium Alloy AZ31 at Room Temperature
Authors: Blažek D. , Palček Peter , Trojanová Zuzanka , Porubčan Jakub
Published: January 2012

The aim of this work is to study the Amplitude Dependent Internal Friction (ADIF) of magnesium alloy AZ31 at room temperature at the frequency 20kHz. The internal friction of AZ31 at room temperature is mostly influenced by mechanical cycling at strain amplitudes in the microplastic deformation region. An excited state of the AZ31 alloy, which can be associated with a higher internal friction and lower dynamic modulus than usual state, was found immediately after mechanical cycling. When the strain amplitude drops, the diffusion of solute atoms restores the Zener atmosphere and the internal friction relaxes exponentially with the second root of time. The measurement methodology and obtained results are presented.
Internal Friction in Extruded Aluminium Alloy
Authors: Porubčan Jakub , Palček Peter , Blažek D. , Trojanová Zuzanka
Published: January 2012

Aluminium alloys have very useful properties. Because they are light, easily formed, machined and cast, they are widely used in aircraft industry and automotive industry. Their mechanical properties are mostly influenced by former mechanical and thermal treatment. An extruded aluminium alloy EN AW – 2007 was used in the as-received state and the specimens were thermally cycled with increasing the upper temperature step-by-step. After each thermal cycle the stress-amplitude dependence of internal friction was measured at room temperature. The quality factor Q-1was measured by a resonant method at a frequency of 20 kHz. Thermal and mechanical treatments influenced the anelastic properties of the material. The thermal treatment affects the internal friction in a positive way, while the mechanical treatment decreases Q-1. The microstructural changes were observed by optical microscopy.
The IF Spectrum of Fe-C-N and Fe-17%Cr-C-N Alloys Measured by the Impulse Excitation Technique
Authors: Jung I. , De Cooman Bruno C.
Published: January 2012

The temperature dependence of the dynamic Young’s modulus, E, and the damping, Q-1, of Fe-C-N and Fe-17%Cr-C-N alloys with different C, N contents were studied in the temperature range of 25°C to 600°C by the impulse excitation internal friction technique at 1KHz. Hot rolled samples were cold rolled to a thickness of 1.2mm and recrystallization annealed at 820°C for 30sec then gas jet cooled (-50°C/sec). Samples were subsequently tensile strained 6% and 16%. A Snoek peak was observed at 120°C in the undeformed sample and a Snoek-Koster peak was observed at 400°C after deformation. In the case of the Fe-Cr-C-N alloy, a high damping background due to magneto-mechanical damping was observed in the temperature range of 25°C to 400°C. A broaden Snoek peak in FeCr was observed at 300°C. The internal friction peaks observed in this study showed the strong dependence of the amount of interstitial contents and deformation and were well correlated to previous internal friction studies measured mainly by torsion pendulum and inverted torsion pendulum.
Anelastic Effects on Martensitic Carbon Steels during First Stage of Tempering
Authors: Hoyos J.J. , Ghilarducchi A.A. , Salva H.R. , Vélez J.M.
Published: January 2012

The evolution of martensitic carbon steel during low temperature tempering was studied using internal friction. The steel containing 0.71wt.% carbon was heated at 1093K for 5min and then rapidly cooled into water (quenched), and tempered for 10 min at 340, 380, 420 and 460K. Additionally, other samples were tempered at 380K for 1 and 20 hours. Internal friction was measured by using a forced vibration pendulum, in a temperature range from 300 to 600K, with deformation amplitude 3 x 10-6 and temperature rate of 0.8 K/min. The internal friction spectrum is decomposed into three Debye peaks: P1 at 380K, P2 at 420K and P3 at 480K, for 3 Hz. P1 is attributed to the epsilon carbide precipitation. P2 and P3 are associated to the dislocation relaxation process. P2 appears when dislocations are pinning with epsilon carbide and P3 appears when dislocations are pinning with cementite carbide.