bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Characterization of Pt/YSZ Electrode of Zirconia Oxygen Sensor
Authors: Han Qing , Liu Ge Ming , Peng Niu Sheng , Feng Tao , Xia Jin Feng , Xia Jin
Published: March 2013

Electrode slurry made of Pt powder was brushed on both surfaces of the sintered ZrO2 substrate. And then the Pt electrodes were sintered under various temperatures. The microstructure of the surface of the electrodes was characterized by scanning electronic microscope. The electrochemical properties of the electrodes were investigated by electrochemical impedance spectroscopy (EIS). The results show that the sintered temperature of the electrode has a remarkable effect on the microstructure of the electrode and the Pt electrode show favorable electrochemical catalysis performance.
NiO Sensing Electrode for NOx Detection at High Temperature
Authors: Feng Tao , Xia Jin Feng , Nian Hong Qiang , Huang De Xin , Xu Hai Fang , Li Yu Lin , Xu Bing , Jiang Dang Yu
Published: March 2013

Mixed-potential-type NO2 sensor based on yttria-stabilized zirconia(YSZ) with NiO sensing electrode was prepared by the screen-printing technique and its physical characteristics were studied by the X-ray diffraction and scanning electron microscope. The response of electromotive force (EMF) and complex impedance of the sensor were tested under different NO2 concentrations and temperatures. The results show that, at the range of 550–750 °C, the EMF values are negative and almost linear to the logarithm of NO2 concentration. But the sensitivity of the sensor and the amplitude of the EMF response to NO2 concentration both obviously decrease with the increase of the work temperature. In addition, the semicircular arcs of the complex impedance spectra shrink regularly with a raise of NO2 concentration at 600 °C.
The Mechano-Chemical Synthesis and Characteristics of PMN and PZT
Authors: Shi Wu Chao , Chen Cheng , Wu Hao , Jiang Dan Yu , Li Qiang
Published: March 2013

Both PMN and PZT are perovskite oxides and typical functional materials applicable to various devices for its chemistry and physics properties. The conventional method solid-state reaction method has some drawbacks of high reaction temperature, large particle size and limited degree of chemical homogeneity. So, an easy, low cost and environmental method of synthesizing fine and homogenous powders is required. This paper discusses the synthesis of PMN and PZT by the new mechano-chemical method, the screw grinding method. Through experiments, it was found that the mechanism of mechano-chemical method and solid phase diffusion method were completely different, thus the pyrochlore phase was avoided, and the phase purity of powders was developed. And a higher power could greatly short the time of the mechano-chemical reaction time, improving the phase purity and the dispersion of the powder.
A Theoretical Study on the Performance of SnO2/SiO2/n-Si Solar Cells
Authors: Noor Fatimah A. , Oktasendra Fandi , Sustini Euis , Mikrajuddin Abdullah , Khairurrijal Khairurrijal
Published: March 2013

The performance of SnO2/SiO2/n-Si solar cells was studied by considering various transport mechanisms including minority-carrier diffusion, carrier recombination, and tunneling through insulating layer. The tunneling current through the SiO2 layer was obtained by employing the Airy-wavefunction approach. The efficiency was calculated to determine the performance of the cells under AM1 illumination for different values of insulating layer thickness, interface state density, hole life-time, doping density of silicon substrate, and cell thickness. It was shown that the efficiency increases as the insulating layer becomes thinner due to the decrease of short-circuit current. It was also shown that the efficiency increases as the doping density increases up to 6x1022/m3 and it then decreases for higher doping densities. As the interface state density decreases, the efficiency becomes higher. In addition, the increases in the hole lifetime and cell thickness enhance the efficiency of the solar cell.
Modeling of I-, T- and V-Shaped Microcantilevers for Environmental Monitoring
Authors: Nuryadi Ratno
Published: March 2013

This paper describes a model of microcantilever to determine the optimal dimensions that can be used for environmental monitoring. Three types, which are usually used i.e., I-, T- and V-shaped microcantilevers, are considered. The microcantilevers work in dynamic mode in which their resonance frequencies depend on both spring constant and effective mass. It can be seen that the spring constant and effective mass of the microcantilever change when the structure is changed even the size is same. In consequent, the sensor sensitivity is also found to be different each other. The V-shaped microcantilever is more sensitive than I- and T-shaped ones. Moreover, the simulation results show that the microcantilever with sizes of length 10 µm, width 5 µm and thickness 100 nm is good enough to detect molecule gas with the mass of less than femtogram.
Organic Semiconductors: Applications in Solar Photovoltaic and Sensor Devices
Authors: Sulaiman Khaulah , Ahmad Zubair , Fakir Muhamad Saipul , Abd Wahab Fadilah , Mah Abdullah Shahino , Abdul Rahman Zurianti
Published: March 2013

Organic semiconductor-based solar photovoltaic cells and sensors are scalable, printable, solution processable, bendable and light-weight. Furthermore, organic semiconductors require low energy fabrication process, hence can be fabricated at low cost as light-weight solar cells and sensors, coupled with the ease of processing, as well as compatibility, with flexible substrates. Organic semiconductors have been identified as a fascinating class of novel semiconductors that have the electrical and optical properties of metals and semiconductors. The continuous demand to improve the properties of organic semiconductors raises the quest for a deep understanding of fundamental issues and relevant electronic processes. Organic semiconductor thin film is sandwiched between two metal electrodes of indium tin oxide (ITO) and aluminum to form organic photovoltaic solar cell. Several types of organic semiconductors have been utilized as the photoactive layer in the solution processable organic solar cells. The performance of the fabricated solar cells can be improved by dissolving the material in the right choice of solvent, annealing of organic thin film, slowly forming the thin film and introducing an infra-red absorbance layer. Besides, organic semiconductor-based sensors can be fabricated utilizing either in a sandwidch type or planar type device. Some of these techniques and the experimental results are presented.
Preparation of Magnetite Nanoparticles by Thermal Decomposition of Iron (III) Acetylacetonate with Oleic Acid as Capping Agent
Authors: Haryono Agus , Harmami Sri Budi , Sondari Dewi
Published: March 2013

The thermal decomposition of organometallic compounds was used to synthesize magnetite nanoparticles in high boiling point organic solvent containing stabilizing surfactants. Iron (III) acetylacetonate was used as the organometallic precursor in this work. Thermal decomposition of cationic metal center leads directly to the metal oxide, in the presence of 1,2-hexadecanediol, oleylamine, and oleic acid in diphenyl ether. Characterization with the Particle Size Analyzer (PSA) showed the size of the obtained magnetite nanoparticles was 2.1 ± 0.9 nm with polydispersity index of 0.327. The morphology and chemical structure of the obtained magnetite nanoparticle was characterized by using of Transmition Electron Microscopy (TEM) and Fourier-Transformed Infrared (FTIR) spectroscopy. The application of magnetite nanoparticles in the industrial wastewater treatment was also discussed.
PVA-Ketoprofen Nanofibers Manufacturing Using Electrospinning Method for Dissolution Improvement of Ketoprofen
Authors: Pamudji Jessie S. , Khairurrijal Khairurrijal , Mauludin Rachmat , Sudiati Titi , Evita Maria
Published: March 2013

Background and purpose: Ketoprofen is an NSAIDs agent which has analgesic and anti inflammation effects. Ketoprofen is classified into class II in the biopharmaceutical classification system that has a high permeability but low solubility. Hence, the absorption rate of this substance is governed by its dissolution rate. Electrospinning is a method that combine solid dispersion technology and nanotechnology. This method can be selected to enhance the dissolution rate of active substances. The aim of this research is to improve the dissolution rate of ketoprofen through the preparation of polymeric nanofiber polivinyl alcohol (PVA) containing ketoprofen using electrospinning process. Methods: Preparation of nanofibers with various of PVA-ketoprofen ratio, flow rate, and PVA concentration in the solution were accomplished using electrospinning instrument. Casting solid dispersion film were also prepared by solvent evaporation method and used as a reference. The rates of dissolution of ketoprofen from each of nanofibers, casting films, and pure ketoprofen were conducted in HCl pH 1.2 medium at 37oC. Characterization of nanofibers was carried out using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). Results: Nanofibers which contained of PVA-ketoprofen 1:1 in ratio w/w showed a significant improvement in dissolution (p<0.05) compared to the pure ketoprofen. Meanwhile, nanofibers obtained from a solution containing 7.5 % PVA (w/v) and 4 ml/h in flow rate showed the best dissolution rate improvement and significantly different (p<0.05) with either the casting film or the pure ketoprofen. The improvement of ketoprofen dissolution was due to the increasing of surface area of nanofiber and the change of ketoprofen from crystalline into amorphous form. Conclusion: Electrospinning technique can be used to improve the dissolution rate of ketoprofen through the PVA-ketoprofen nanofiber formation by choosing the appropriate polymer concentration and manufacturing process.
Syntheses of Hematite (α-Fe2O3) Nanoparticles Using Microwave-Assisted Calcination Method
Authors: Nurhayati Tati , Iskandar Ferry , Khairurrijal Khairurrijal , Mikrajuddin Abdullah
Published: March 2013

Hematite (α-Fe2O3) nanoparticles were synthesized from the solution of FeCl3.6H2O and NaOH in water using microwave-assisted calcination method. The syntheses were initially carried out by microwave heating and completed by a calcination process using a simple heating method. The effect of microwave heating time, calcination temperature, and calcination time were investigated. The XRD patterns demonstrated that the obtained nanoparticles are pure hematite. Using the Scherrer method, the average crystallite sizes of hematite nanoparticles were in the range of 35.6 to 54.4 nm. The obtained hematite nanoparticles were spherical with the average particle sizes ranging from 91 to 116 nm as confirmed by the SEM images.
Synthesis of NixFe3-xO4 Nanoparticles by Microwave-Assisted Coprecipitation and their Application in Viscosity Reduction of Heavy Oil
Authors: Nugraha Mohamad Insan , Noorlaily Prawistin , Abdullah Mikrajuddin , Khairurrijal Khairurrijal , Iskandar Ferry
Published: March 2013

NixFe3-xO4 nanoparticles have been synthesized using microwave-assisted coprecipitation. Samples were prepared by using FeCl3•6H2O, FeSO4•7H2O, NiCl2•6H2O, and NH4OH as precursors. Concentrated black precipitates were produced after samples were heated in microwave 500 W 2.45 GHz for 3 minutes. According to X-Ray diffractogram, it was indicated that the NixFe3-xO4 was obtained. According to Scanning Electron Microscope (SEM) characterization, it was shown that Ni0.3Fe2.7O4 nanoparticles have spherical morphology and average particle size about 43 nm. In this research, NixFe3-xO4 nanoparticles were applied as catalyst in the reduction of heavy oil via aquathermolysis. In catalytic activity test, Fe3O4 and Ni0.3Fe2.7O4 nanoparticles were added respectively to the mixture of water and heavy oil in autoclave on temperature 120°C for 6 hours. Experimental result showed that the viscosity of heavy oil reduced 30% and 17% when Fe3O4 and Ni0.3Fe2.7O4 powders were added in aquathermolysis reaction, respectively.
Design of Hot Roll Press to Fabricate TiO2-Coated Fiber for Decomposing Rhodamine B in Water
Authors: Arutanti Osi , Nurmala Sandra Sundari , Khairurrijal Khairurrijal , Abdullah Mikrajuddin
Published: March 2013

We have designed new coating equipment for applying nanoparticles of TiO2 on nylon fiber surfaces. A roll hot press with a motor speed of 1740 rpm was able to synthesis ±227 cm/min coated fibers. This equipment is simple and does not require any adhesive materials for attaching Ti02 nanoparticles on the fiber surface. The fiber was passed through a dispersion of TiO2 nanoparticles and then passed through a roll hot press at heating temperature between 600C and 700C. The TiO2-coated fibers were then used for decomposing rhodB-solutions under solar illumination. We observed the TiO2-coated fibers did not affect to properties of TiO2 as catalyst in photocatalysis. The best result was observed when 0,5 gr TiO2-coated fibers were suspended into 250 ml of rhodB-solution in water with a concentration of 1,6 %w/v.
Effect of Size of Cellulose Particle as Filler in the PVC Biocomposites on their Thermal and Mechanical Properties
Authors: Ghozali Muhammad , Haryono Agus
Published: March 2013

The combination between synthetic polyolefin with natural polymer such as cellulose, starch and chitosan can stimulate biodegradation processes of waste plastics such as polyethylene (PE), polypropylene (PP) and other conventional plastics. In this work, PVC (polyvinyl chloride) biocomposite was prepared by compounding cellulose particle into PVC matrix in the presence of PVC-g-maleic anhydride as a compatibilizer. Cellulose nanoparticles were prepared by physical top-down method after milling by using High-Energy Ball-mill. The diameter size of cellulose nanoparticle was obtained as 170 nm. Cellulose particles were added as filler with ratio of 10-30 phr in PVC matrix. PVC biocomposites was prepared as a sheet film with the thickness of 0.3 mm by hot-press method. The addition of cellulose particle into PVC matrix was examined in various filler volumes and various cellulose particle sizes. The obtained PVC composite films were characterized by means of Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and Fourier-Transformed Infrared (FTIR) spectroscopy. The rheological and mechanical properties of PVC and cellulose composites were investigated as a function of surface structure and filler volume fraction.
Effect of Solvent Used in the Preparation of Aluminum-Doped ZnO as Electron Acceptor Layer on the Characteristic of its Hybrid Solar Cell
Authors: Aprilia Annisa , Wulandari Priastuti , Hidayat Rahmat
Published: March 2013

Aluminum doped Zinc Oxide (AZO) layer has been employed as electron acceptor in hybrid solar cell based on Poly(3-hexylthiophene) with inverted structure. AZO layers used in this work were prepared by sol-gel process using two different solvents, namely methanol and methoxyethanol. From X-ray diffraction measurements, AZO layer prepared using methanol solvent (AZO-me) indicates the formation of crystallines with the same (002) orientation, whereas AZO layer prepared using methoxyethanol (AZO-mx) indicates the formation of crystallines with (100), (002), and (101) orientations. The nanomorphology of those AZO layer surfaces was also remarkably different, which might be related to differences in crystal orientation. For both solvents, the photocurrent density-voltage (J-V) characteristics were also affected by the Al ion concentration in AZO layer. However, solar cell with AZO-mx shows better performances in comparison to that of AZO-me with the same Al ion concentration. The observation of performance variations in those fabricated solar cells are suggested to be strongly related with the crystal orientation and nanomorphology of AZO layer. These experimental results then suggest that charge carrier dissociation by AZO layer are significantly influenced by the crystal orientation and nanomorphology of AZO layer, which are affected by the solvent used for preparing the AZO layer.
Hydrogen Adsorption Behavior of Mechanically Milled and Pelletized Coconut Shell Activated Carbon
Authors: Harjanto Sri , Yunior Stefanno Widy , Chodijah Siti , Nasruddin Nasruddin
Published: March 2013

Activated carbon can be the best selection for the solid media of hydrogen storage materials because of cheap, good availability, high quantity of pore on its surface and good adsorption capacity. To obtain optimal handling of coconut charcoal-based (CSAC) without reducing its property on hydrogen adsorption capacity, the effect of mechanochemical and pelletizing process to CSAC was examined. Mechanical milling by using planetary ball mill was conducted to reduce particle size distribution and to mechanochemically process CSAC with KOH. CSAC particles reduce its particle size distribution to nano and sub micron size due to mechanical milling. After mechanochemical and pelletizing process, the surface area and pore volume of CSAC decrease to 68.5% and 61% compared with those of as received sample. However, hydrogen adsorption capacity of CSAC pellet only decrease 5 and 9% at measurement pressure and temperature of 4000 kPa, -5oC and 4000 kPa, 25oC, respectively.
Stress-Free Strains in Martensitic Microstructures
Authors: Peigney Michaël
Published: March 2013

The peculiar properties of shape-memory alloys are the result of a solid/solid phase transformation between different crystallographic structures (austenite and martensite). This paper is concerned with the theoretical prediction of the set of strains that minimize the effective (or macroscopic) energy. Those strains, classically refered to as recoverable strains, play a central role in shape memory effect displayed by alloys such as NiTi or CuAlNi. They correspond to macroscopic strains that can be achieved in stress-free states. Adopting the framework of nonlinear elasticity, the theoretical prediction of stress-free strains amounts to find the austenite/martensite microstructures which minimize the global energy. Closed-form solutions to that problem have been obtained only in few special cases. This paper aims at complementing existing results on that problem, essentially by deriving bounds on the set of stress-free strains.
The Influence of Nanocrystalline Structure of Iron on α-ε Phase Transformations under Pressure
Authors: Pilyugin V.P. , Patselov Alexander , Tolmachev Timofey , Chernyshov Eugeny , Ancharov Alexey , Brytkov Dmitriy
Published: March 2013

Martensitic α-ε transformation in iron under high pressure was investigated. Using of advanced spectroscopic techniques allow to reveal the influence of nanocrystalline structure on critical points of the above transformation. Comparison both structure evolution and critical points is presented by using the terminology and basic positions of martensitic transformations. The results of experimental observations for coarse-grained and nanocrystalline samples are discussed.
EM Characterization of Precipitates in as-Cast and Annealed Ni45.5Ti45.5Nb9 Shape Memory Alloys
Authors: Shi Hui , Frenzel Jan , Schryvers Dominique
Published: March 2013

Nb-rich precipitates in the matrix of as-cast and annealed Ni45.5Ti45.5Nb9 alloys are investigated by scanning and scanning transmission electron microscopy, including slice-and-view and geometric phase analysis (GPA). The Nb-rich bcc nano-precipitates in the as-cast alloy have a 10% lattice parameter difference with the B2 matrix and reveal compensating interface dislocations. The 3D reconstruction of the configuration of small Nb-rich precipitates in the annealed alloy reveals a wall-like distribution of precipitates, which may increase the thermal hysteresis of the material.
Phase Transformations and Shape Memory Effect in Alloys of Zr-Ni-Co System
Authors: Kosorukova Tetiana , Firstov Georgiy , Koval Yuri , Ivanchenko Volodymyr , Van Humbeeck Jan
Published: March 2013

Intermetallic compounds of ZrNi-ZrCo cross-section undergo martensitic phase transformation, which is accompanied by the imperfect shape memory effect at elevated temperatures. Martensitic transformation is also taking place in one of the constituents for the in-situ composites of ZrCo-Zr2Co-Zr2Ni-ZrNi region. High temperature shape memory behavior of Zr-Ni-Co composite material shows improvement in shape recovery comparing to quasibinary intermetallic compounds of ZrNi-ZrCo cross-section.
Precursor Nanoscale Textures in Ferroelastics: Interplay between Anisotropy and Disorder
Authors: Castán Teresa , Planes Antoni , Saxena Avadh
Published: March 2013

We study the effect of anisotropy and disorder on the morphology of precursor microstructures within a Ginzburg-Landau free energy framework. In addition, with increasing disorder at low anisotropy we find a crossover from a twinned state to a non-transforming frozen state. Results are compared with available experimental data.
Internal Friction during Reverse Martensitic Transformation in Mn-Cu Alloy with 45 % Mn
Authors: Markova Galina Viktorovna , Klyueva Ekaterina Sergeevna
Published: March 2013

The temperature and amplitude dependence of internal friction fcc Mn45Cu55 alloy aged at 400 °C were studied. Two low-temperature internal friction peak observed in the quenched state. Physical mechanism of the peaks was determined by the effect of frequency and strain amplitude on the temperature dependence of internal friction. The influence of the heat treatment to the internal friction of the investigated alloy was shown.
Influence of Omega-Phase Precipitation Hardening on the Static and Dynamic Properties of Metastable Beta Ti-Nb-Zr and Ti-Nb-Ta Alloys
Authors: Brailovski Vladimir , Prokoshkin Sergey , Inaekyan Karine , Dubinskiy Sergey
Published: March 2013

The influence of thermomechanical processing on the Ti-21.8Nb-6Zr (TNZ) and Ti-19.7Nb-5.8Ta (TNT) (at%) alloys’ structure, phase composition, mechanical and functional properties is studied. Both alloys possess polygonized dislocation substructure (average subgrain size  100 nm), and manifest superelastic behavior at room temperature and recovery stress generation during constant-strain temperature scanning experiments. After aging treatment, both alloys were -phase precipitation hardened, but their mechanical behavior was impacted differently -- it was detrimental for TNZ and beneficial for TNT. The different impact of aging heat treatment on the mechanical behavior of these alloys is explained by the differences in the -phase nucleation rate, precipitates’ size, shape, volume fraction and distribution, and by their effect on the alloys’ critical stresses and transformation temperatures.
Structural Mechanism of Reverse α → γ Transformation and New Functional Properties of Fe-Ni Austenitic Alloys
Authors: Sagaradze V.V. , Kabanova I.G. , Kataeva N.V. , Klyukina M.F.
Published: March 2013

The structure of the metastable austenite Fe–32%Ni alloy quenched for martensite and subjected to the α→γ transformation at slow heating (to 593–773 K) with the formation of a nanocrystalline austenite of different orientation was investigated. Electron diffraction analysis has revealed that nickel-enriched nanocrystalline γ-phase obtain ordered L10 superstructure. Together with the γ-phase, there was detected the disperse ε-martensite with a hexagonal close-packed (hcp) lattice. Along with the realization of ordinary orientation relationships (ORs) of Kurdjumov-Sachs, between a matrix α-phase and an ordered γ-phase in the sample of Fe-32%Ni alloy after slow heating to 773 K there have been established Headley-Brooks Ors. Cyclic transformation promotes the improvement of many functional properties of steels (strength, coercive force, controlling of the thermal expansion coefficient and others).
Influence of Mechanical Loading, Temperature and Chemical Composition on the Deformation Induced Martensite Formation in Metastable Austenitic Steels
Authors: Hahnenberger Frank , Skorupski Robert , Smaga M. , Eifler Dietmar
Published: March 2013

The deformation induced α´-martensite formation in the metastable austenitic steels AISI 304, AISI 321 and AISI 348 was investigated in tensile and low cycle fatigue tests at ambient and low temperature. By means of stress strain and magnetic measurements, the mechanical behavior and phase transformation were characterized. The susceptibility of deformation induced α´-martensite formation depends on the chemical composition, the temperature and the degree of cumulated plastic strain. On the basis of comprehensive experimental data a mathematical model was developed to describe and predict the α´-martensite formation under cyclic loading in the temperature range -60 °C to 25 °C. The influence of test temperature and austenite stability of the model parameters was studied.
Study of Metallurgy and Mechanical Property on Japanese Sword
Authors: Yaso Muneo , Minagi Yoshihiro , Takaiwa Toshifumi , Kubota Kunichika , Kanaizumi Tsuyoshi , Ohba Takuya , Morito Shigekazu , Hayashi Taisuke
Published: March 2013

Japanese sword has finer grain size and lath martensite in the microstructure of sharp edge amazingly. Nowadays these structures are considered to be one of the ideal structure at which are greatly aimed to strengthen or improve toughness of steels. Though the carbon content of its sharp edge is 0.70 mass %, there are no lenticular martensite and no micocracking in that area. As a result of bending test by actual sword specimen, one sword was finally bent, the other sword was broken. However it is found the sharp edge in Japanese sword has such a large bending strength 2500, 4600MPa respectively as modern, high performance tool steels and the difference of crack propagation under bending depends on the microstructure distribution and the grain size in cross section of Japanese sword.
Effect of Titanium Carbide Inclusions on Morphology of Low-Carbon Steel Martensite
Authors: Pham Hoang Anh , Ohba Takuya , Morito Shigekazu , Hayashi Taisuke , Furuhara Tadashi , Miyamoto Goro
Published: March 2013

The effect of titanium carbide (TiC) on morphology of low-carbon steel martensite was studied by means of electron backscatter diffraction (EBSD). The nucleation and growth of new morphology subunits such as packet, block and sub-block are observed in the area surrounding of micron-sized TiC particles. The misorientation from a fitted orientation relationship between martensite and austenite near TiC particle is larger than the average misorientation with a localized characteristic. The position of new morphology subunits has a well correspondence with the area in vicinity of TiC particle, which has large misorientation. The micron-sized TiC particle plays a role of stress concentrator in austenite during martensitic transformation which suppresses growth of one martensite variant while stimulates nucleation and growth of another one.
Shape Recovery in Stainless FeMnSiCrNi(-Co) SMA Processed by ECAE
Authors: Bernardi Heide Heloise , Käfer Karine Andrea , Naito Leonardo K.F. , Otubo Jorge
Published: March 2013

Stainless shape memory steel presents reasonable shape recovery but lower than the traditional NiTi shape memory alloys (SMA). However, recent results have shown that the shape recovery could be improved by decreasing the austenitic grain size. The present work describes the influence of the austenitic grain size on the shape recovery in stainless shape memory steel deformed by equal channel angular extrusion (ECAE) using a die intersection angle of 120o. Two alloys, FeMnSiCrNi and FeMnSiCrNiCo, were deformed by 1 ECAE pass and then they were compared in the deformed state; deformed and annealed in different temperatures for 1 h, resulting different grain sizes. Both alloys were evaluated by compression tests and the results shows an increase in total shape recovery related to grain size decrease. The best total shape recovery was 73% after a pre-strain of 4% for FeMnSiCrNi alloy.
Effect of Cold-Rolling Rate on Texture in Ti-Mo-Al-Zr Shape Memory Alloy
Authors: Hiramatsu Katsunori , Tahara Masaki , Inamura Tomonari , Hosoda Hideki , Miyazaki Shuichi
Published: March 2013

Effect of rolling rate on texure of Ti-Mo-Al-Zr shape memory alloy was investigated using X-ray diffraction pole figure measurement and electron backscattering pattern (EBSP) analysis to optimize the thermomechanical processing. Ti-Mo-Al-Zr alloy is a candidate Ni-free shape memory alloy to replace Ti-Ni alloy in medical applications. The alloy was single phase of β before rolling and then α''-martensite was induced during the cold-rolling. Unlike the recrystallization texture in Ti-Nb alloy system, {110}ββ recrystallization texture of β-phase was developed by the solution-treatment especially in the specimens with the reduction rate higher than 90%. This texture has never been observed in Ti-Nb based alloys and can exhibit a larger recovery strain in both tension and compression.
Identification and Interpretation of Material Parameters of a Shape Memory Alloy (SMA) Model
Authors: Piotrowski Boris , Chemisky Yves , Meraghni Fodil , Echchorfi Rachid , Bourgeois Nadine , Patoor Etienne
Published: March 2013

The thermomechanical behavior of Shape Memory Alloys (SMAs) is described by many micromechanical and phenomenological models. The first ones have material parameters whose physical meaning is based on the crystallography of the phase transformation related to the studied alloy. In contrast, phenomenological models often have material parameters whose physical meaning is not obvious and that makes them difficult to identify, some of which are based on mathematical considerations. In this paper, we propose to use the formulation of the phenomenological model of Chemisky et al., and to consider the particular case of a superelastic SMA. In this case, the constitutive equation should be easily expressed analytically through the strain tensor as a function of applied load direction and material parameters. The behavior is then characterized by a complete and proportional loading. This analytical model contains 8 material parameters, 2 related to the elasticity and 6 to the phase transformation. Based on several isothermal tensile tests at various temperatures, material parameters of this model are identified using the Levenberg-Marquardt algorithm and an analytical calculation of the sensitivity matrix. Their physical meaning and their influence on the thermomechanical behavior of the alloy studied are highlighted and discussed.
Evolution of Temperature Profiles during Stress-Induced Transformation in NiTi Thin Films
Authors: Krevet Berthold , Pinneker Viktor , Rhode Magnus , Bechthold Christoph , Quandt Eckhard , Kohl Manfred
Published: March 2013

This paper presents a time-resolved investigation of tensile loading induced temperature profiles in pseudoelastic NiTi thin film specimens. A finite element model for coupled mechanical and time dependent thermal analysis is presented that accounts for the different effects of local generation of latent heat and heat transfer. For strain rates larger than 0.24/s, the maximum temperature increases from room temperature to above 50 °C. Subsequent stress relaxation after temperature compensation results in a temperature decrease from room temperature down to -20 °C. The observed evolution of temperature profiles is in qualitative agreement with infrared thermography experiments on NiTi films fabricated by magnetron sputtering.
Peculiarities of Thermoelectric Force Behaviour in Nikelide Titane upon Non-Stationary Heating
Authors: Rubanik Vasili V. , Rubanik Jr. Vasili V. , Petrova-Burkina Olga A.
Published: March 2013

The phenomena of appearance of thermo-emf at non-stationary heating in equiatomic titanium nickelide was examined. The peculiarities of kinetics of display of thermokinetic emf, also during thermocycling were determined. The possibility of generation of thermo-emf in amorphous-crystalline ribbon of Ti50Ni25Cu25 during the transition to crystalline state was determined.
Features of Electroplastic Deformation and Electropulse Treatment for TiNi Alloys
Authors: Stolyarov Vladimir V.
Published: March 2013

Influence of the combined action severe deformation and a pulse current on a microstructure and mechanical behavior of long-size rods and strips with thin section out of Ti50Ni50 and Ti49.3Ni50.7 alloys is presented. Dependence of electroplastic effect on phase composition of the initial alloys is demonstrated. It is established, that electropulse postdeformation processing promotes acceleration of a stress relaxation at stages of recovery, polygonization and recrystallization in alloys.
Study of Surface State Influence on Functional Poperties of Ti-Ni Alloys
Authors: Ryklina Elena P.
Published: March 2013

Binary TiNi alloys containing 50.0 at.% Ni and 50.7 at.% Ni were tested under bending. Shape memory effect (SME) and two-way SME (TWSME) parameters were measured. Low-temperature thermomechanical treatment (LTMT) by drawing with true strain e ≈ 0.6 and post-deformation annealing (PDA) was performed in the temperature range 300600С for 0.3  1 hr permitted obtaining different types of initial austenite structure. The wires with 0.3 and 0.45 mm in diameter were studied. The curves of element distribution through the surface layer were graphed. The SME training procedure was carried out in bending with the constrained strain 0.7 and 8 %. Thickness, structure and element composition of the oxide film strongly depend on PDA regimes. In all cases titanium quantity in the boundary layer correlates with the oxygen quantity, diffused from the surface. Evidently, it is caused by their chemical reaction and oxide formation. Nickel atoms remain in uncombined state, and their migration is directed from the surface deep into the sample. LTMT permits decreasing the film thickness more than by 10 times. Surface state strongly affects all studied parameters: characteristic temperatures, recovery strain and TWSME value. Increasing of wire diameter from 0.3 to 0.45 mm leads to significant changes of studied parameters. Forecasting of said influence is difficult because of its ambiguity. Therefore, the oxide film must be eliminated by etching in order to obtain the reliable results
Effect of Annealing on the Transformation Behavior and Mechanical Properties of Two Nanostructured Ti-50.8at.%Ni Thin Wires Produced by Different Methods
Authors: Wang Xie Bin , Amin Ahmadi Behnam , Schryvers Dominique , Verlinden Bert , Van Humbeeck Jan
Published: March 2013

A Ti-50.8at.%Ni wire produced using a co-drawing method and a commercial Ti-50.8at.%Ni wire were annealed between 450°C and 700°C. Grains with diameter less than 100nm were revealed by TEM for both wires before annealing treatment. However, the microstructural heterogeneity of the co-drawn wire is more obvious than that of the commercial wire. The transformation behavior and mechanical properties of both wires were found to be sensitive to the annealing temperature. Multi-stage martensitic transformation was observed in the co-drawn wire, compared with the one-stage A↔M transformation in the commercial wire after annealing at 600°C for 30min. Moreover, the ultimate tensile stress and plateau stress of the commercial wire were found to be higher than that of the co-drawn wire under the same annealing conditions. The differences of total elongation, plateau strain and pseudoelastic recoverable strain between the commercial wire and the co-drawn wire were also observed. The differences of the transformation behavior and mechanical properties between the commercial wire and the co-drawn wire are attributed to the microstructural difference between these two wires.
Influence of the Structure on the Strain-Controlled Fatigue of Nitinol
Authors: Kollerov Mikhail , Lukina Elena , Gusev Dmitiy , Mason Peter , Wagstaff Paul
Published: March 2013

The influence of increased dislocation density; dispersity of Ni-rich (Ti3Ni4 and Ti2Ni3) particles and volume fraction of Ti-rich (Ti2Ni) particles on the low-cycle (high amplitude) and high-cycle (low amplitude) fatigue resistance of nitinol has been considered in this paper. It was revealed that the fatigue resistance of nitinol in low-cycle conditions may be improved by increasing the part of deformation which is realized by martensitic mechanism. This part may be estimated by measuring εcr, which can reflect the influence of the structure parameter both on σM and σslip. It was found that in high-cycle fatigue conditions the substructure of nitinol predominantly determine its fatigue resistance, which is being the better in samples that had higher dislocation density or high dispersity of Ni-rich particles (up to 30 nm).
Functional Properties of TiNi Shape Memory Alloy after High Strain Rate Loading
Authors: Bragov Anatoly M. , Galieva Alesia , Grigorieva Viktoria , Danilov Anatoly , Konstantinov Alexandr Yu. , Lomunov Andrey K. , Motorin Alexander , Ostropiko Eugeni , Razov Alexander
Published: March 2013

The review on effect of a high strain rate on the properties of TiNi-shape memory alloys is presented. The study of thermo-mechanical and functional properties of SMA after high strain rate loading was carried out. The object of study was an equiatomic TiNi shape memory alloy. The samples were tensioned at a strain rate of about 103 s-1 at various temperatures in martensitic, austenitic, and two-phase state, using the Split Hopkinson Pressure Bar technique. Two-way shape memory effects were investigated. Two-way shape memory after high strain rate loading was less than after the quasi-static one for all cases, except for straining in martensitic state.
Superelasticity of Single Crystalline Fe-30.8 at.%Pd Alloy
Authors: Xiao Fei , Yashima Kaname , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2013

We have investigated superelastic behavior of an Fe-30.8Pd (at.%) alloy. This alloy transforms from a FCC parent phase to a FCT martensite phase at 255 K with a latent heat of 38 J/mol. When a compressive stress is applied in the [001] direction above the transformation temperature, the specimen exhibits a large elastic-like strain of more than 3% under relatively small stress of 100 MPa. The large elastic-like strain mainly comes from the elastic strain of the parent and martensite phases. The transformation strain also contributes to the strain, but it decreases linearly with increasing temperature and stress. The transformation strain || is extrapolated to be about 1.4 % under zero stress, and 0 % under 100 MPa. Probably a critical point, at which first order nature of the transformation disappears, exists for the FCC to FCT transformation in Fe-Pd alloys.
Influence of Low Temperature Glow Discharge Nitriding and/or Oxiding Process on Structure and Shape Memory Effect in NiTi Alloy
Authors: Lelątko Józef , Lekston Zdzisław , Wierzchoń Tadeusz , Goryczka Tomasz
Published: March 2013

In order to increase corrosion resistivity of the NiTi alloy the surface is covered by layers. Layers can be made from such as titanium nitrides and/or oxides as well as their mixture. Recently, a glow discharge technique has been applied for coatings formation. However, the deposition process requires to be done at elevated temperature. Therefore, it may have a negative effect on the structure, which is responsible for the shape memory phenomena. The results obtained from studies, done over the influence of the glow discharge nitriding and combination of nitriding and oxidizing process on the structure, the kinetics of martensitic transformation, the one-way shape memory effect and the superelasticity effect of the NiTi alloys are reported. The results showed that during deposition process, curried out at temperatures above 250°C and for time up to 30 minutes, the precipitation of dispersive particles of Ni4Ti3 phase already starts and has a positive effect on the superelasticity phenomena. The applied deposition technique does not affect also negatively the shape memory effect.
Study of Two-Way Shape Memory Behavior of Amorphous-Crystalline TiNiCu Melt-Spun Ribbons
Authors: Shelyakov Alexander , Sitnikov Nikolay , Saakyan Sergey , Menushenkov Alexey , Rizakhanov Razhudin , Korneev Alexander
Published: March 2013

Recently we reported on the development of a composite material exhibiting reversible shape memory effect. A Ti–25Ni–25Cu (at.%) alloy was obtained by the melt spinning technique as amorphous–crystalline ribbons with a thickness of approximately 40 μm. The thickness of the amorphous and crystalline layers (dа and dc, respectively) was varied by electrochemical polishing. It has been ascertained that with varying the relationship dc/dа the martensite transformation and shape-recovery temperatures do not actually change, while the minimum radius of the ribbon bending decreases from 8.0 mm to 2.4 mm with increasing the relationship dc/dа from 0.33 to 1.40. The maximum reversible strain comprises 0.4% at dc/dа = 0.82. On the basis of experimental data obtained the phenomenological description, providing an explanation for nature of the phenomena taking place in the rapidly quenched amorphous-crystalline ribbon composite, has been proposed.
NiTi Splat Features during Vacuum Thermal Spraying onto Several Substrates
Authors: Cinca Nuria , Isalgué Antonio , Fernández Javier , Sampath S.
Published: March 2013

Vacuum Plasma Spraying has been used to produce coatings onto steel substrates. This work deals with the study of splat morphology of the NiTi alloy sprayed by VPS onto different substrates (aluminium, copper, stainless steel, glass and alumina). All the previous characteristics are discussed in terms of wettability and thermal conductivities regarding the rapid cooling involved in the process. Although identical conditions were used during thermal spraying, a wide variety of splat formations were observed; commonly, slushy or splash/disc splats are formed depending on whether the particles have partially or fully melted. The thermal effusivity of the substrate material, which is a measure of its ability to exchange thermal energy with its surroundings, seems to play an important role promoting more or less spreading. The higher the thermal effusivity is, the more rapidly the splats are cooled, thus starting the solidification before they come to rest and, changing their morphology.
Influence of Ultrasonic Treatment on Shape Memory Effects in Ti-50,4at.%Ni Alloy
Authors: Rubanik Vasili V. , Rubanik Jr. Vasili V. , Dorodeiko Vyacheslav , Miliukina Svetlana
Published: March 2013

In the present study we investigate the effect of ultrasonic treatment on the functional properties of Ti 50,4at.%Ni alloy after the processing in free and pre-deformed conditions. It is shown that the shape memory effect and its realization peculiarities depend on the parameters and conditions of ultrasonic influence. Ultrasonic treatment of preliminary deformed TiNi alloy in pre-deforming conditions promotes the reduction of strain restoring at the subsequent heating through the temperature interval of reverse martensite transformation. I. e. some setting of induced strain occurs during the ultrasonic treatment of material in pre-deforming conditions. In the specimens after ultrasonic treatment, it is observed the extension of shape recovery temperature range in the first thermal cycle, as well as the dependence of strain recovery temperature dynamics on the power of ultrasonic influence. Also it is established that ultrasonic treatment helps to increase the shape memory effect.
Unusual Multistage Martensitic Transformation in TiNi Shape Memory Alloy after Thermal Cycling
Authors: Sibirev Aleksey , Belyaev Sergey , Resnina Natalia
Published: March 2013

Variation in kinetics of martensitic transformation, in an equiatomic TiNi shape memory alloy, during thermal cycles was investigated. Samples annealed at 500 °C for 1 hour were subjected to repeated thermal cycles, through the temperature range of martensitic transformation. Unusual 4-stage martensitic transformation during cooling after 30 thermal cycles was observed. Moreover, a new unusual phenomenon was found in the preliminary thermal cycled TiNi alloy. It was observed that variation in the highest temperature Th of thermal cycles temperature interval resulted in the redistribution of released heat among four calorimetric peaks, observed on cooling. It was found that if the Th temperature did not exceed 240 °C the variation in kinetics was repeatable, and determined only by the value of Th. It was assumed that the defect structure induced on preliminary thermal cycling changes reversibly on cooling and heating.
Effect of Partial Thermal Cycles on Non-Chemical Free Energy Contributions in Polycrystalline Cu-Al-Be Shape Memory Alloy
Authors: Daróczi Lajos , El Rasasi Tarek , Beke Dezső L.
Published: March 2013

Abstract. Thermoelasic martensitic transformations are controlled by the local equilibrium of chemical and non-chemical free energy contributions (D and E being the dissipative and elastic energies, respectively). The derivatives of non-chemical free energies ( ) as a function of the transformed martensite fraction (ξ) can be expressed from the experimental data obtained from the temperature-elongation, temperature-resistance, etc hysteresis loops. This method, developed in our laboratory, was used for the investigation of non complete, partial thermoelastic transformation cycles. In the first set of experiments the subsequent cycles were started below the Mf temperature and the maximum temperature was decreased gradually from a value above Af (series U). In the second (L) set the cycles were started above the Af and the minimum temperature was gradually increased from a value below Mf. In the third (UL) set the minor loops were positioned into the centre of the two phase region (i.e. the cycling was made with an increasing T temperature interval with T0.5 and <0.5, respectively. On the other hand the d() functions show a maximum at about the central point of the sub-cycles, and deviate considerably from the d() function obtained from the full cycles. This is also reflected in the  dependence of the integral value of the dissipative energy, D(): its value for the partial loops is lower than the dissipative energy calculated from the full cycle for the same transformed fraction interval. An opposite tendency (i.e. higher values for the partial loops) was obtained for the integral value of the elastic energy, E. The relative values of the dissipated energies, D, (calculated from the areas of the minor loops and normalized to the area of the major loop) are not very sensitive to the details of the cycling process, i.e. they are very similar for all sets.
Deformability and Shape Memory Properties in Ti50Ni50 Rolled with Electric Current
Authors: Potapova Anna A. , Stolyarov Vladimir V.
Published: March 2013

It is shown that deformability of Ti50.0Ni50,0 alloy at the rolling with current is considerably above than at the cold rolling. The influence of deformation with a current and without a current on feature of martensitic transformations was investigated. Recovery strain and recovery stress were studied on heating the sample subjected to preliminary strain by a three-point bending and optimal regimes of electroplastic rolling were defined.
A Miniature Energy Harvesting Device Using Martensite Variant Reorientation
Authors: Kohl Manfred , Yin Rui Zhi , Pinneker Viktor , Ezer Yossi , Sozinov Alexei
Published: March 2013

This paper presents a miniature energy harvesting device that makes use of stress-induced cyclic martensite variant reorientation in a Ni-Mn-Ga single crystal of 0.3x2x2 mm³ size. The stress- and magnetic field-induced reorientation is investigated for single crystalline Ni50.2Mn28.4Ga21.4 specimens of 0.3 mm thickness that are cut along the (100) direction and subjected to uniaxial compressive loading. A demonstrator is presented consisting of a FSMA specimen placed in the gap of a magnetic circuit to guide and enhance the field of biasing permanent magnets. The cyclic motion of a piezoelectric bimorph actuator is used to mechanically load the FSMA specimen. The corresponding change of magnetic flux induces an electrical voltage in a pick-up coil (N=2000 turns). The effects of biasing magnetic field, strain amplitude and strain velocity are investigated. An optimum magnetic field of 0.4 T exists, where the output voltage reaches 120 mV at a strain velocity of 0.006 ms-1.