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دسترسی آزاد مقاله
1 - Calculating formation range of binary amorphous alloys fabricated by electroless plating
Bangwei Zhang Shuzhi Liao Xiaolin Shu Haowen XieAbstractA lot of amorphous alloy deposits in the binary (Ni, Co, Cu)–(P, B) alloy systems fabricated by electroless plating (EP) have been reported up to date. But no one reported their theoretical modeling of the amorphous formation and calculated their concentration r چکیده کاملAbstractA lot of amorphous alloy deposits in the binary (Ni, Co, Cu)–(P, B) alloy systems fabricated by electroless plating (EP) have been reported up to date. But no one reported their theoretical modeling of the amorphous formation and calculated their concentration range of amorphous formation (RAF). Using Miedema model and subregular model scheme, the RAFs for the six EP (Ni, Co, Cu)–(P, B) alloys and three Ni–Cu, Ni–Co and Co–Cu alloys have been calculated systematically for the first time. The calculated results are in agreement with experimental observations. Experiments and calculations for the RAFs in the latter three alloy systems reveal that not any RAF formed except crystalline states. The huge difference between the six metal–metalloid alloys and three metal–metal alloys in RAF has been discussed in detail in the paper. پرونده مقاله -
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2 - Micromagnetic analysis of Heusler alloy-based perpendicular double barrier synthetic antiferromagnetic free layer MTJs
Bahniman Ghosh Kshitij DwivediAbstract We investigate spin transfer torque switching in a perpendicular double barrier synthetic antiferromagnetic free layer MTJ stack using micromagnetic simulations. For the material used in free layers, we use two different Cobalt-based Heusler alloys and compare چکیده کاملAbstract We investigate spin transfer torque switching in a perpendicular double barrier synthetic antiferromagnetic free layer MTJ stack using micromagnetic simulations. For the material used in free layers, we use two different Cobalt-based Heusler alloys and compare their performance on the basis of switching speed, thermal stability and Tunnel magnetoresistance. We show that for Heusler alloys switching from one state to other is significantly faster but they suffer from the drawback of low thermal stability. پرونده مقاله -
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3 - Effect of Ta Addition on Microstructure and Hot Oxidation Resistance of AlCrCoNiY-xTa High-Entropy Alloy Consolidated by Spark Plasma Sintering
Babaei Rouchi A Salemi Golezani A Hadavi S. M. MHigh Entropy Alloys(HAEs) are alloys with multiple elements (typically 5 or more elements) that remain in solid solution state instead of precipitate in several phases. These alloys are multicomponent alloys having constituents in equiatomic or near equiatomic ratios (h چکیده کاملHigh Entropy Alloys(HAEs) are alloys with multiple elements (typically 5 or more elements) that remain in solid solution state instead of precipitate in several phases. These alloys are multicomponent alloys having constituents in equiatomic or near equiatomic ratios (having the atomic percentage between 5% and 35%). In this paper, the effects of Ta addition on the microstructure and oxidation behavior of 4 High and Medium Entropy Alloys were investigated with the aim of understanding the relationship between phase / microstructure and oxidation resistance of AlCrCoNiY-xTa alloys. The microstructure investigations showed that the presence of Ta alloying element could lead to the formation of CrTaO4 phase. The amount of this phase increases with a higher percentage of Ta element. Also, more results show that, formation of CrTaO4 phase facilitates the formation of Al2O3 oxide phase as an outer layer and the presence of this phase can improve the oxidation properties of the investigated alloys پرونده مقاله -
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4 - Investigation on Hot Tearing Susceptibility of A201 Aluminum Alloy in Different Ingate Velocities and Molds
M. H Ayandeh A. A Kashi M. Ghambarian H. Karimi A. Mootabha A. Khoyini E.M. BoushehriIn this research, Hot tearing Behavior and susceptibility of the Al-Cu A201 aluminum alloy in different mold has been investigated. There are a lot of methods that used for hot tear tests but between all of these methods that proposed for this kind of the tests, The Rin چکیده کاملIn this research, Hot tearing Behavior and susceptibility of the Al-Cu A201 aluminum alloy in different mold has been investigated. There are a lot of methods that used for hot tear tests but between all of these methods that proposed for this kind of the tests, The Ring model was employed for testing the hot tearing tendency. In order to increase the investigated parameters, wooden model designated to support different ingate velocities. Some samples that exposed to the Hot Tear were inspected by visual and NDT (None destructive) tests followed by Scanning Electron Microscopy (SEM) to study of the teared surface of the samples. The extracted results show that the number and severity of tears increased by changing the strength of mold from green sand to CO2 sand. The evaluation of the experimental results in this study showed that these results is in good agreement with the other obtained by another researchers پرونده مقاله -
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5 - The Influence of Oxidized Interlayer on the Adhesion of Bioactive Cao-P2o5-Tio2-Na2o Glass Ceramic Coating to the Titanium Substrate
Sh. Honarvar B. Eftekhari YektaTitanium alloys are important bio materials which may also need to a bio compatible coating. To improve the Ti/glass-ceramic bonding is a challenging part of coating because the bonding properties play an important role in the long-term performance of medical implants. چکیده کاملTitanium alloys are important bio materials which may also need to a bio compatible coating. To improve the Ti/glass-ceramic bonding is a challenging part of coating because the bonding properties play an important role in the long-term performance of medical implants. The purpose of this research is to improve the bonding strength of bioactive coating in the system of CaO-P2O5-Na2O-TiO2 using the formation of suitable oxidized layer and studying the effect of this interlayer on adhesion of coating. To achieve this goal, after surface modification, the surface of titanium samples was heat treated in 750 ˚c for 30, 60 and 90 min, to be oxidized. The results of Scanning Electron Microscopy (SEM) and Elemental concentration analysis by EDS and Atomic Force Microscopy (AFM) show that oxidized layer that was produced in 750˚c and 30 min. This oxidized interlayer has the best properties in comparison with two other samples and has the best adhesion to both substrate and coating. پرونده مقاله -
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6 - Investigation on the Simultaneous Effects of Zn Additions and Critical Ingate Velocity on the Hot Tearing Susceptibility of A356 and A206 Aluminum Alloys
M. Ghambarian S.M.A. Boutorabi F. ShahriIn this study, the simultaneous effects of Zn addition and critical gate velocity on hot tearing susceptibility of A356 and A206 aluminum alloys were investigated. In order to investigate these two parameters, ingate velocities of 0.5, 0.75, 1, 1.5 m/s were taken into a چکیده کاملIn this study, the simultaneous effects of Zn addition and critical gate velocity on hot tearing susceptibility of A356 and A206 aluminum alloys were investigated. In order to investigate these two parameters, ingate velocities of 0.5, 0.75, 1, 1.5 m/s were taken into account. After performing the casting process, the samples were investigated by visual examination, and scanning electron microscopy. In order to quantitative evaluation of results, ProCast software were used. The results of the present study showed that increasing the Zn content for alloy A356, had no effect on hot tearing susceptibility of this alloy, while with increasing the Zn content from 0.01 to 2.8 wt%, the number and severity of the tears were increased. پرونده مقاله -
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7 - An Investigation of the Fatigue Corrosion Behavior of Al 6063-T6 Alloy under Seawater Influence
R. Abdollahi M. Hajisafari A. Zare BidakiThe purpose of the present study was to investigate the fatigue behavior of Al-6063 alloy using standard rotating-bending test. Corrosion-fatigue test on similar samples was also performed at stress levels corresponding to fatigue test. The samples obtained from fatigue چکیده کاملThe purpose of the present study was to investigate the fatigue behavior of Al-6063 alloy using standard rotating-bending test. Corrosion-fatigue test on similar samples was also performed at stress levels corresponding to fatigue test. The samples obtained from fatigue tests were considered as control samples and the results obtained from fatigue test in air were compared to the results obtained from corrosion-fatigue test in liquid seawater. Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) were used to investigate the micro-structural features and crack characteristics of the specimens. The results obtained from fatigue and corrosion-fatigue test revealed that the presence of corrosion environment decreases the fatigue life. Additionally, microstructure studies on the fracture surface due to corrosion-fatigue revealed that initiation of fatigue crack starts from the depth of corrosion steps and proliferate towards the sample center simultaneous with the penetration of liquid into the crack. Moreover, the appearance, size and propagation way of fatigue crack in corrosion-fatigue test was completely different from the cracks created in a fatigue test. The fracture surface due to corrosion-fatigue test was also different from the fatigue fracture surface. Further studies on failure levels revealed that the ratio of region area due to fatigue to the region area due to final failure was strongly decreased in the corrosion-fatigue test. پرونده مقاله -
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8 - Comparison of the Annealing Heat-Treated Microstructure and Hardness of the AA2024-T4 and AA6061-T6 Alloys
A Anbarzadeh H Sabet A Granmayeh UrmiaPrecipitation Hardenable Aluminum Alloys are suitable alternatives in electric vehicle bodies due to their lower specific weight compared to steel. Therefore, the development and understanding of the properties of aluminum alloys help to develop electric vehicles, reduc چکیده کاملPrecipitation Hardenable Aluminum Alloys are suitable alternatives in electric vehicle bodies due to their lower specific weight compared to steel. Therefore, the development and understanding of the properties of aluminum alloys help to develop electric vehicles, reduce greenhouse gas emissions, and control global warming. In this research, we investigated the heat treatment of AA2024-T4 and AA6061-T6 alloys at a temperature of 453 °C for 210 minutes in a tube furnace with a heating rate of 5 oC/min in a vacuum (7.5×10-13 Torr). The alloys were assessed by optical microscopy (OM), scanning electron microscopy (SEM), and hardness test. The effect of heat treatment was investigated on the particle size as well as the phases. The particle diameter and hardness value of AA2024-T4 decreased after heat treatment. The number of precipitates in AA2024-T4 increased after heat treatment. Precipitates size in AA6061-T6 alloy remained almost unchanged after the heat treatment. پرونده مقاله -
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9 - Studies on the Microstructure Modification and Tribological Characteristics of Cast Al-Si Eutectic Alloys
V Abouei Mehrizi O BayatiThe focused of this investigation is on the modification of Fe-rich intermetallics morphology and wear and friction properties of eutectic Al-Si alloys. Eutectic Al-Si specimens were fabricated by tilt casting technique after addition of different amounts of iron and ma چکیده کاملThe focused of this investigation is on the modification of Fe-rich intermetallics morphology and wear and friction properties of eutectic Al-Si alloys. Eutectic Al-Si specimens were fabricated by tilt casting technique after addition of different amounts of iron and manganese to the melt alloy. Dry sliding tribological behavior of the samples were investigated using a reciprocating wear tester at the room temperature in atmospheric environment. It is found that the addition of iron up to 1.5 wt.pct to the alloy decreased the wear resistance of alloy owing to the formation of brittle plate-like β-Al5FeSi intermetallic compounds. As Manganese is added to the β-containing alloy up to the half of iron content (corresponding to a Mn/Fe ratio of 0.5), the platelet phases are completely replaced by the star-like α-Al15(Fe,Mn)3Si2 intermetallics resulting in improved wear resistance of the alloy. Introducing 0.8 wt.pct Mn to the alloy containing 1.6 wt.pct Fe did not convert the plate-like beta intermetallics to the modified alpha compounds completely and had no impressive impact on the wear rate of the alloy. پرونده مقاله -
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10 - Prediction Micro-Hardness of Al-based Composites by Using Artificial Neural Network in Mechanical Alloying
R, M Babaheydari S, O MirabootalebiAluminum composites are one of the most important alloys with a wide range of properties and applications. In this paper, we predict the micro-hardness of aluminum-based alloys by artificial neural method (ANN). First, the effective parameters in mechanical alloying inc چکیده کاملAluminum composites are one of the most important alloys with a wide range of properties and applications. In this paper, we predict the micro-hardness of aluminum-based alloys by artificial neural method (ANN). First, the effective parameters in mechanical alloying include weight percentage and micro hardness of reinforcement materials, milling time, the ball to powder weight ratio, vial speed, the pressure of presses, sintering time and temperature, selected for inputs and micro-hardness of Al composite considered as the output. A feed-forward back propagation artificial neural network designed with 16 and 10 neurons in the first and second hidden layers, respectively. The created network with the mean percentage error of 5.6% was able to predict micro hardness of the Al composites. Finally, the effect of each parameter was determined by sensitivity analysis which volume fraction of alloying elements, milling speed and sintering time had the highest impact on the micro hardness of Al-based composites. پرونده مقاله -
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11 - Evaluation Microstructure and Hardness of the Fe-Cr-C Hardfacing Alloy with Cr/C=6 Ratio
H SabetIn this investigation, different amount of carbon and chromium content of Fe-Cr-C hardfacing alloys with the constant ratio of Cr/C=6 were used. These alloys were fabricated by GTAW on AISI 1010 mild steel substrates to achieve hypo/eutectic/hyper compositions. OES, XRF چکیده کاملIn this investigation, different amount of carbon and chromium content of Fe-Cr-C hardfacing alloys with the constant ratio of Cr/C=6 were used. These alloys were fabricated by GTAW on AISI 1010 mild steel substrates to achieve hypo/eutectic/hyper compositions. OES, XRF, OM, SEM, XRD techniques and HV method were used for determining chemical composition, hardness and studying the microstructure of hardface alloys. The metallographic examination results indicated that all hardface samples had three metallurgical zones with different thickness, microhardness, chemical composition and solidification modes. The microstructures of all hardface samples in thicker Zone consists of austenite and chromium-iron carbides (Cr,Fe)7C3. Moreover with increasing of carbon and chromium content of thicker zone in hardface samples, the volume fraction of (Cr,Fe)7C3 increased and resulted in the decreasing of austenite volume fraction and increasing hardness of the top surface. A multiple regression model was used to determine the relation between microstructure, chemical composition and hardness پرونده مقاله -
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12 - Physical and Numerical Investigations of Gas Turbine Blades Failure
H.R. Faridi A. Momeni M. Mohammadpour V. SarfaraziTwo blade samples from the first and second stages of a gas turbine were investigated to understand the reason of fracture. All samples suffered excessive heat superficially. Using a TBC layer on top of Diffusion coating will be a reasonable solution for protecting the چکیده کاملTwo blade samples from the first and second stages of a gas turbine were investigated to understand the reason of fracture. All samples suffered excessive heat superficially. Using a TBC layer on top of Diffusion coating will be a reasonable solution for protecting the blades. Although in case of the first stage blades cracking was postponed, the thermomechanical fatigue cracks still originated from the blade surface. It was observed that the damage of the thermal barrier coating layer would lead to the overheating of the blades, promoting the rate of creep and rafting of g¢ precipitates. This phenomenon was more severe in the second stage samples with more damaged protective layers. It was found that the chemical composition of the fuel gas may increase the potential and rate of corrosion and damage to the blades. Concurrent with physical investigation, numerical simulation was performed to study the effect of particle impact into the blade. By changing the particle radii and its position, damage area was inspected. Numerical simulation shows that particle radii and its position have an important effect on the chipping removal from the blade. پرونده مقاله -
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13 - Review of Smart Metallic Materials Classification
H Sabet B Karbakhsh RavariAlong with material science progress, many new high-quality and cost-effective engineering materials have been introduced in various fields. Smart materials are the new generation of materials superior to construction and commonly used materials. With their inherent int چکیده کاملAlong with material science progress, many new high-quality and cost-effective engineering materials have been introduced in various fields. Smart materials are the new generation of materials superior to construction and commonly used materials. With their inherent intelligence, these materials can adapt to external stimuli such as loads or the environment. Smart materials refer to those materials that understand and react to their environment and surrounding conditions. The crystal structure of these materials responds to applied force (mechanical, electrical, magnetic, etc.). According to NASA's definition, smart materials remember positions and can return to them with certain stimuli. Smart materials are used in systems whose inherent properties can be changed to achieve the required performance. In this article, while introducing the application and development of memory metal smart materials, the relationship between the development of advancing technologies and the development and application of this class of material is discussed. پرونده مقاله -
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14 - بررسی رفتار و خواص مکانیکی آلیاژهای حافظه دار در مواد هوشمند و کابرد آن ها در صنایع مختلف
مهدی رضوانی توکلبا رشد و بهبود تکنولوژی اطلاعات در طی بیست سال گذشته، واژه "هوشمند" به شکل فزاینده ای در مورد مواد، اشیاء و محیط به کار گرفته شده است. هوشمندی خاصیتی می باشد که در تمام گروه های مواد یافت شده است. در هردسته از مواد مثل کامپوزیت ها، پلیمرها، سرامیک ها و فلزات پیشرفته می چکیده کاملبا رشد و بهبود تکنولوژی اطلاعات در طی بیست سال گذشته، واژه "هوشمند" به شکل فزاینده ای در مورد مواد، اشیاء و محیط به کار گرفته شده است. هوشمندی خاصیتی می باشد که در تمام گروه های مواد یافت شده است. در هردسته از مواد مثل کامپوزیت ها، پلیمرها، سرامیک ها و فلزات پیشرفته می توان موادی یافت که با اعمال یک سری فرآیندها، خواص هوشمند پیدا کنند. همچنین مواد هوشمند به آن دسته از مواد گویند که می توانند محیط و شرایط اطراف خود را درک نمایند و نسبت به آن واکنش نشان دهند. هم اکنون کامپوزیت ها و فلزات هوشمند در موارد بسیاری کاربرد دارند و جایگاه خود را در صنعت پیدا کرده اند. در این مقاله به بررسی آلیاژهای حافظه دار و همچنین کارایی این نوع مواد هوشمند در صنعت پرداخته شده است. آلیاژهای حافظه دار که در واکنش به تغییرات دما دچار تغییر شکل ناشی از تبدیل فاز می شوند و یکسری مواد دیگر که از خود قابلیت حسگری و تحریک پذیری نشان می دهند را می توان به عنوان مواد هوشمند نام برد. پرونده مقاله -
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15 - The Effects of Mould Materials on Microstructure and Mechanical Properties of Cast A356 Alloy
Musa Yıldırım Dursun ÖZYÜREKAbstract In this study, the effects of mould materials on microstructure and mechanical properties of cast A356 Al alloy were investigated. The alloy was poured into three different moulds. Then the samples were homogenised and applied T6 heat treatment. The optical, Sc چکیده کاملAbstract In this study, the effects of mould materials on microstructure and mechanical properties of cast A356 Al alloy were investigated. The alloy was poured into three different moulds. Then the samples were homogenised and applied T6 heat treatment. The optical, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) studies were made. Secondary dendrite arm spacing (SDAS) was measured by image analysis systems. Hardness and tensile tests were also performed. The ultimate tensile strength (UTS) values were evaluated by Weibull statistical analysis As a result of the studies, the highest values of SDAS were measured for the samples obtained using ceramic mould, which led to the slowest cooling rate, the lowest values of SDAS were measured for the samples obtained using chromite sand mould, which led to the highest cooling rate. The hardness values were increased about 2.5 times which samples were applied T6 heat treatment. The highest tensile strength was observed for the samples obtained using sand mould. پرونده مقاله -
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16 - Friction Stir Welding of Al 2024 with Al 7075 Alloys and evaluate its structural and mechanical properties
Sayedeh Zahra Anvari Saeed Rohani MojaradThe overarching goal of this research was to use the FSW method to join the Al 2024 and Al 7075 alloys, examine the structural and mechanical properties of the joint, and eventually find the optimum welding parameters. The welding operation was carried out using a milli چکیده کاملThe overarching goal of this research was to use the FSW method to join the Al 2024 and Al 7075 alloys, examine the structural and mechanical properties of the joint, and eventually find the optimum welding parameters. The welding operation was carried out using a milling machine and a device with cylindrical pins. The transverse cross-section of the weld was used for optical as well as electron microscopy observations. The evaluation of mechanical properties at room temperature i.e., tensile strength and hardness were done. The size of the grains measured using an optical microscope varied between approximately 2.6 and 11 µm. The results of the welding process revealed that the specimen with a traverse speed of 30 mm/min, a rotation speed of 600 rpm, and the highest ultimate tensile strength (195 MPa), and the specimen with a traverse speed of 70 mm/min, a rotation speed of 1200 rpm, and an ultimate tensile strength of 193 MPa were selected as the optimum specimens due to their off-fusion-zone failure, their high strength in the tensile strength test, and their adequate input heat. Moreover, in the specimen with the traverse speed of 100 mm/min and the rotation speed of 600 rpm, the highest percentage of elongation (3.80%) was observed in the tensile strength test. The results from the tensile test indicated that with a decrease in the traverse speed, the tensile strength of the specimens increased, the elongation percent decreased, and the stirring improved. پرونده مقاله -
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17 - Age-Hardening Behavior and the Related Changes in a Silver-Copper-Palladium Alloy
Morteza Hadi Iman Ebrahimzadeh Omid BayatAge-hardening behavior and related changes were studied to elucidate the hardening mechanism of an Ag–Cu–Pd alloyby Differential Scanning Calorimetry (DSC), hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy d چکیده کاملAge-hardening behavior and related changes were studied to elucidate the hardening mechanism of an Ag–Cu–Pd alloyby Differential Scanning Calorimetry (DSC), hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectrometer (EDS). The results showed that hardness of the alloy was raised to 90% and 68% of its solution state value by isothermal aging at 300 ◦C and 400 ◦C, respectively. However, aging at 500 ◦C led to a decrease in the hardness of the alloy. Moreover, while age hardening at 300◦C occurred due to coherency strains between the (111) plane of Ag-rich and the (111) plane of Cu3Pd phases, the mechanism of aging at 400◦C was the formation ofCu3Pd superlattice with the L12-type crystal structure. In contrast, reduction of Cu3Pd phase and formation of Cu solid solution decreased hardness during aging at 500oC. پرونده مقاله -
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18 - Utilization of Microalloying with Rare Earth Elements and Hot Extrusion for Remarkable Grain Refinement and Enhancement of Mechanical Properties of as-Cast Magnesium Alloy
Hooman Abedi Massoud Emamy Hamed Mirzadeh Jafar Rassizadehghani M. Ra'ayatpourThe effects of micro-addition by rare earth (RE) elements (via cerium-based mischmetal) and hot deformation (via extrusion process) on the microstructure and mechanical properties of Mg-0.5Zn-0.5Zr alloy were studied. Optical microscopy, scanning electron microscopy (SE چکیده کاملThe effects of micro-addition by rare earth (RE) elements (via cerium-based mischmetal) and hot deformation (via extrusion process) on the microstructure and mechanical properties of Mg-0.5Zn-0.5Zr alloy were studied. Optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and tensile testing were used for characterization of alloys in the as-cast and wrought conditions. It was found that the addition of 0.5 wt% RE combined with the hot extrusion process could remarkably refine the grain size from 1320 µm for the as-cast Mg-0.5Zn-0.5Zr alloy to the recrystallized grain size of 1.3 µm for the extruded Mg-0.5Zn-0.5Zr-0.5RE alloy. Compared to the as-cast counterparts, the ultimate tensile strength (UTS) and total elongation to failure were significantly enhanced by the extrusion process. Quantitatively, the UTS of ~ 300 MPa with the total elongation of ~ 18% was obtained for the extruded Mg-0.5Zn-0.5Zr-0.5RE alloy, which reveals the favorable effects of the ultra grain refinement on the enhancement of the mechanical properties of magnesium alloys. پرونده مقاله -
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19 - Vacuum Brazing of Zirconium-Based Alloy and 321 Stainless Steel Using Titanium Based Filler Metal
M.E Bajgholi E Heshmat DehkordiBoth Zirconium-based alloys and 321stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic comp چکیده کاملBoth Zirconium-based alloys and 321stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic compounds such as (Zr3Fe, ZrFe2 and Zr2Fe) and corrosion cracking. Brazing is one of the most widely used techniques for joining dissimilar alloys.Using titanium base filler metal decreases the diffusion and the formation of brittle intermetallic compounds. In this study, wetting experiments were done at 820, 850, 865ºC and 3, 5, 7 and 10 min. Also, joining of these two alloys was carried out at 850 and 865ºC for 10 and 15 minutes. Optical microscope, scanning electron microscope (SEM), XRD, shear test and micro-hardness test were used for metallurgical and mechanical investigations. The results show that 20 ºC/min heating and cooling rates at 850ºC and 10 min brazing condition lead to a proper joint without any brittle intermetallic compounds. پرونده مقاله -
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20 - Fabrication of TiC particulate reinforced Ni-50Fe super alloy matrix composite powder by mechanical alloying
M.H Shirani A Saidi A.R ShiraniMechanical alloying is a powder metallurgy processing technique involving cold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. In this work, NiFe-TiC composite powders were prepared by mechanical alloying process using planetary high-e چکیده کاملMechanical alloying is a powder metallurgy processing technique involving cold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. In this work, NiFe-TiC composite powders were prepared by mechanical alloying process using planetary high-energy ball mill. The effect of TiC addition by weight percent on the NiFe solid solution formation, grain size, lattice parameter, internal strain and hardness of composite powders was investigated as a function of milling time, t, (in the 0-25 h range). Microstructural and phase characterizations investigationof the mechanically alloyed powders were carried out using X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results showed that the brittle particles of TiC accelerate the milling process by increasing the matrix deformation and enhancing the welding and the fracture of particles. We also found that the NiFe solid solution formation occurred at earlier time of mechanical alloying with increasing the TiC content. Moreover, it was shown that with increasing the TiC by weight percent, smaller crystallite size and more hardness are obtained after mechanical alloying. پرونده مقاله -
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21 - Ab initio (first principle) material modeling study on Lio adsorbed by palladium-cobalt (PdCo) nanoparticles
Mikail AslanPdCo subnanoalloys have been commonly used as a catalytic material in some important chemicalreactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms ofunderstanding the role of catalysis, these smallest bimetallic nanoparticles provide چکیده کاملPdCo subnanoalloys have been commonly used as a catalytic material in some important chemicalreactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms ofunderstanding the role of catalysis, these smallest bimetallic nanoparticles provide the simplestprototypes of Pd-Co bimetallic catalysts for different compositions. In this study, the effect ofLixO (x=1,2) on PdCo nanoalloys has been investigated comprehensively employing the densityfunctional theory (DFT) to identify the mechanism of structural, electronic, and energeticproperties of the studied species. Binding energies are calculated for stability analysis, whichis very important for nanoparticles. Results show that lithium oxides are generally adsorbed bycobalt sites on the Pd-Co substrate. This is important for determining active sites of the catalyticmaterial. Furthermore, the structures have low symmetric properties. Hence, this study mightprovide an initial structural evaluation step for future studies related to the possible new catalyticmaterial of Li-air batteries. پرونده مقاله -
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22 - Prediction of Heusler Alloys with Giant Magnetocaloric Effect using Machine-Learning
Tasnim Gharaibeh Pnina Ari-Gur Elise de DonckerHeusler alloys are intermetallic that offer a unique and broad array of properties. These properties are both scientifically intriguing and valuable for a variety of beneficial practical applications. One of these applications is magnetic cooling, taking advantage of th چکیده کاملHeusler alloys are intermetallic that offer a unique and broad array of properties. These properties are both scientifically intriguing and valuable for a variety of beneficial practical applications. One of these applications is magnetic cooling, taking advantage of the giant magnetocaloric effect (GMCE) in some Heusler alloys. Since the late 1990s, numerous scientific papers were published, attempting to harness Heusler alloys for green refrigeration. Manufacturing the alloys by additive manufacturing further offers control and enables tuning of their properties by controlling their microstructure. Although the scientific literature contains extensive information on these alloys’ chemistry and performance, it is the massive volume of scientific papers that makes it difficult, if not impossible, to keep up to date with relevant discoveries. To enable predicting the composition of excellent performing giant magnetocaloric Heusler alloys, manufactured by laser powder bed fusion (LPBF), we employed artificial intelligence, specifically unsupervised learning in the current work. We trained an unsupervised learning model using word embedding and the Word2vec algorithm on different data sets in the literature to extract hidden knowledge, relations, and interactions based on words that appear in similar contexts in the text while often having similar meanings. Properties inherent to giant magnetocaloric materials were addressed in the model. The outcome was the prediction of Heusler alloys, manufactured by LPBF, with an excellent giant magnetocaloric effect. پرونده مقاله -
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23 - Characterization and Investigation of Grain Selection in Spiral Grain Selectors during Casting Single-Crystal Turbine Blades
Hassan Gheisari Ebrahim KaramianManufactured single crystal components using Ni-base super alloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative en چکیده کاملManufactured single crystal components using Ni-base super alloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative environments. To control the quality of the single crystal turbine blades, particular attention has been paid to grain selection, which is used to obtain the single crystal morphology from a plethora of columnar grains. For this purpose, different designs of grain selectors are employed and the most common type is the spiral grain selector. A typical spiral grain selector includes a starter block and a spiral (helix) located above. It has been found that the grains with orientation well aligned to the thermal gradient survive in the starter block by competitive grain growth while the selection of the single crystal grain occurs in the spiral part. In the present study, 2Dspiral selectors with different geometries were designed and produced using a state-of-the-art Bridgeman Directional Solidification casting furnace to investigate the competitive growth during grain selection in 2d grain selectors. The principal advantage of using a 2-Dselector is to facilitate the wax injection process in investment casting by enabling significant degree of automation. The directional solidification process for obtaining single crystal component for Nickel Super alloys based on the competitive growth in 2D and 3D single crystal grain selector was experimentally investigated for various geometries. Transverse sections of the grain selectors using optical and EBSD microscopy techniques were observed to understand the competitive grain growth process. پرونده مقاله -
دسترسی آزاد مقاله
24 - An Investigation on Formability and Crystallographic Texture in Novel Magnesium Alloys
Pnina Ari-Gur Andreas Quojo Quainoo Shubram Subramanyam Ashkan Razania Sven C. Vogel Wei GaoMagnesium alloys offer many advantages. They offer the very low density and good strength. They also offer good damping properties. One of the industries where reducing component weight in the automotive industry. That makes the magnesium alloys good candidates for thes چکیده کاملMagnesium alloys offer many advantages. They offer the very low density and good strength. They also offer good damping properties. One of the industries where reducing component weight in the automotive industry. That makes the magnesium alloys good candidates for these applications. Reduced weight of an automobile means also lower fuel consumption. The hexagonal closed packed structure of magnesium lends itself to strong mechanical anisotropy. In the current work, neutron diffraction was used to study the crystallographic texture developed in novel magnesium alloys during cold rolling operations. The texture was compared with that developed in the commercial AZ-31 magnesium alloy. Tests were run at the High-Pressure-Preferred-Orientation (HIPPO) beamline at Los Alamos National Lab. The texture was then analyzed using pole figures, created using the Material Analysis Using Diffraction (MAUD) software. پرونده مقاله -
دسترسی آزاد مقاله
25 - The Effect of Artificial Aging Treatment and Lubrication Modes on the Cutting Force and the Chip Surface Morphology when Drilling Al-Si-Mg (A356) Cast Alloys
Seyed Ali Niknam Keyhan JabbariThis article reports the effects of various artificial aging methods and lubrication modes (dry, mist, wet) on the recorded cutting forces and chip morphology in drilling Al-Si-Mg (A356) cast alloys. In the course of this work, the work part sampled were as-received all چکیده کاملThis article reports the effects of various artificial aging methods and lubrication modes (dry, mist, wet) on the recorded cutting forces and chip morphology in drilling Al-Si-Mg (A356) cast alloys. In the course of this work, the work part sampled were as-received alloy (T0), solution heat-treated alloy (SHT) and then aged alloys at 155°C, 180°C, and 220°C (T4, T6, T61, T7), respectively. The significant effects of artificial aging the recorded cutting forces were noticed. Except minor cases under lower levels of feed rate, in general lower cutting forces were observed in A356-T0 and A356-T7 which are more brittle than other tested alloys. A direct relationship can be formulated among the microcracks on the free surfaces of the chips, brittleness and the recorded cutting forces. The use of MQL led to lower resulting cutting forces under similar cutting conditions. This can be related to less effect of thermo-mechanical stresses on the work part under MQL mode which tends to reduce the cutting forces. پرونده مقاله -
دسترسی آزاد مقاله
26 - Efficient synthesis of xanthene derivatives in aqueous media in the presence of Cu-anchored furfural imine-functionalized halloysite
Samahe SadjadiA novel hybrid catalyst based on grafting Cu on furfural imine-functionalized halloysite was designed, characterized and used for promoting synthesis of xanthene derivatives via three- component reaction of benzaldehyde derivatives, dimedone, and β-naphthol in aque چکیده کاملA novel hybrid catalyst based on grafting Cu on furfural imine-functionalized halloysite was designed, characterized and used for promoting synthesis of xanthene derivatives via three- component reaction of benzaldehyde derivatives, dimedone, and β-naphthol in aqueous media and under mild reaction condition. The results established high catalytic activity of the hybrid system, which was superior to some conventional catalysts. Moreover, the catalyst was reusable and could be easily recovered and reused for several reaction runs with slight loss of catalytic activity. Broad substrate scope, simple work up procedure and performing the process in aqueous media are other merits of this protocol. پرونده مقاله -
دسترسی آزاد مقاله
27 - مطالعه و بررسی تشکیل نانوکامپوزیت زمینه بین فلزی NbAl3 با ذرات تقویت کننده Al2O3: بررسی ریزساختاری، ترمودینامیکی و آنالیز حرارتی
حسین مستعان مهدی رفیعی محمد حسن عباسی فتح الله کریم زادههدف از انجام این پژوهش، تولید نانوکامپوزیتی با زمینه NbAl3 توسط روش آلیاژسازی مکانیکی به منظور افزایش چقرمگی و استحکام دما بالای آن میباشد. به این منظور مقدار 49 درصد وزنی پودر آلومینیوم به همراه 51 درصد وزنی اکسید نیوبیوم مخلوط و آلیاژسازی مکانیکی گردید. تغییرات فازی چکیده کاملهدف از انجام این پژوهش، تولید نانوکامپوزیتی با زمینه NbAl3 توسط روش آلیاژسازی مکانیکی به منظور افزایش چقرمگی و استحکام دما بالای آن میباشد. به این منظور مقدار 49 درصد وزنی پودر آلومینیوم به همراه 51 درصد وزنی اکسید نیوبیوم مخلوط و آلیاژسازی مکانیکی گردید. تغییرات فازی ذرات پودر و همچنین ریزساختار و مورفولوژی ذرات پودر در زمان های مختلف آسیاب کاری توسط آزمون های پراش پرتو ایکس (XRD)، میکروسکوپ الکترونی روبشی (SEM) و میکروسکوپ الکترونی عبوری (TEM) مطالعه شدند. عملیات آنیل و همچنین آنالیز حرارتی افتراقی (DTA) جهت بررسی رفتار حرارتی ذرات پودر انجام شد. مشاهده شدکه واکنش بین آلومینیوم و اکسید نیوبیوم به صورت انفجاری بوده که در نتیجه این واکنش نانوکامپوزیت زمینه بین فلزی NbAl3 با ذرات تقویت کننده Al2O3 شکل میگیرد. مخلوط پودری آسیاب نشده نیز توسط DTA مورد مطالعه قرار گرفت که نتایج نشان داد در این شرایط تشکیل کامپوزیت NbAl3/Al2O3 در دو مرحله صورت میگیرد. در مرحله اول اکسید نیوبیوم پنج ظرفیتی توسط آلومینیوم موجود در سیستم احیا شده و نیوبیوم تشکیل میشود. در مرحله دوم آلومینیوم باقیمانده از واکنش با نیوبیوم تولید شده وارد واکنش شده که در نهایت کامپوزیت NbAl3/Al2O3 شکل میگیرد. مشاهدات صورت گرفته توسط میکروسکوپ الکترونی عبوری، تشکیل ساختار نانومتری و ذرات تقویت کننده نانومتری را تأیید مینماید. پرونده مقاله -
دسترسی آزاد مقاله
28 - بررسی جوشکاری لیزر پالسی در آلیاژ آلومینیوم 6061 بر اساس پیش بینی مدلهای فیزیکی ایجاد ترک گرم
حسین ابراهیم زاده حسن فرهنگی سید علی اصغر اکبری موسویببه وسیله مدلهای فیزیکی ارتباط بین متغیرهای جوشکاری و ترک گرم بر قرار میشود. این مدلها در مقیاسهای میکرو، میانه و ماکرو موجود هستند. در این پژوهش ورقی از جنس آلومینیوم 6061 به وسیله یک دستگاه لیزر پالسی Nd:YAG مورد جوشکاری قرار گرفت. برای اولین بار قطر بازوهای دندری چکیده کاملببه وسیله مدلهای فیزیکی ارتباط بین متغیرهای جوشکاری و ترک گرم بر قرار میشود. این مدلها در مقیاسهای میکرو، میانه و ماکرو موجود هستند. در این پژوهش ورقی از جنس آلومینیوم 6061 به وسیله یک دستگاه لیزر پالسی Nd:YAG مورد جوشکاری قرار گرفت. برای اولین بار قطر بازوهای دندریتی در جوش لیزر آلومینیوم اندازهگیری و نتایج با مدلهای انجمادی مقایسه شد. بر خلاف پیشبینی مدلهای ایجاد ترک گرم افزایش قطر بازوهای دندریتی، کاهش سرعت انجماد و کاهش نرخ کرنش باعث کاهش ترکهای گرم نشد. اگرچه بر اساس مدلهای موجود پیشگرم میبایست از مقدار ترکهای گرم بکاهد ولی برعکس مقدار ترکها را به شدت افزایش داد. تصاویر دوربینهای سرعت بالا و بررسیهای سطح ترک به وسیله میکروسکوپ الکترونی روبشی نشان داد که ایجاد ترک در جوشکاری لیزر پالسی سه مرحلهای است: 1) شروع ترک، 2) رشد ترک مرحله اول 3) رشد ترک مرحله دوم. رشد ترک در مرحله دوم در مرزدانههای ضعیف ولی منجمد شده انجام میگیرد. آنچه در نهایت به عنوان ترک در جوش ایجاد میشود مجموعهای از ترک گرم و ترک دمای بالا است و بنابراین مدلهایی که برای جوشکاری پیوسته در نظر گرفته میشوند نیاز به اصلاح بر اساس شرایط ذوب و انجماد پالسی دارند و باید شکست مرزدانههای ضعیف بعد از انجماد نیز در نظر گرفته شوند. پرونده مقاله -
دسترسی آزاد مقاله
29 - تأثیر زمان اتصال بر ریزساختار و تکمیل انجماد ایزوترم در خلال اتصال TLP سوپر آلیاژهای پایه نیکل غیرمشابه IN738LC و Nimonic 75
میثم خاکیان قمی محمد سعید شهریاری سعید ناطقاتصال سوپر آلیاژهای پایه نیکل اینکونل 738 و نایمونیک 75 با استفاده از لایه واسط حاوی Ni-Cr-B و با نام تجاری MBF-80 توسط فرآیند فاز مایع گذرا (TLP) در دماهای ℃1080، ℃1120، ℃1150 و ℃1180 و زمانهای مختلف انجام شد. ریزساختار اتصال با استفاده از میکروسکوپ الکترونی روبشی (SE چکیده کاملاتصال سوپر آلیاژهای پایه نیکل اینکونل 738 و نایمونیک 75 با استفاده از لایه واسط حاوی Ni-Cr-B و با نام تجاری MBF-80 توسط فرآیند فاز مایع گذرا (TLP) در دماهای ℃1080، ℃1120، ℃1150 و ℃1180 و زمانهای مختلف انجام شد. ریزساختار اتصال با استفاده از میکروسکوپ الکترونی روبشی (SEM) و میکروسکوپ نوری مورد مطالعه قرار گرفت. بررسیهای ریزساختاری نشان داد که در زمانهای کوتاه اتصال، ریزساختار شامل فازهای بین فلزی یوتکتیکی پیوسته در خط مرکزی اتصال میباشد و با افزایش زمان اتصال در دمای ثابت بهتدریج از پیوستگی آن کم و نهایتاً بهطور کامل حذف میشوند. بهمنظور پیشبینی زمان لازم برای تکمیل انجماد ایزوترم از معادلات نفوذ فیک استفاده شد و مشاهده گردید که تطابق خوبی بین زمان پیشبینی شده برای تکمیل انجماد ایزوترم و نتایج تجربی وجود دارد. پرونده مقاله -
دسترسی آزاد مقاله
30 - A brief review on titanium alloy for dental, biotechnology and biomedical applications
Sharif Heydari Maryam Sadat Mirinejad Mohammd Hossein Malekipour Esfahani Fatemeh Karimian Ali Attaeyan Mehran LatifiTitanium (Ti) used for various application due to its light, durable and polished silver-white element. Titanium has two forms of allotropy called rutile and anatase, due to white color, slow-melting point in uniform distribution and diffusion in other compounds. It is چکیده کاملTitanium (Ti) used for various application due to its light, durable and polished silver-white element. Titanium has two forms of allotropy called rutile and anatase, due to white color, slow-melting point in uniform distribution and diffusion in other compounds. It is known for making paper, plastics, rubber and various other materials. Therefore, regarding its use and high application in this paper we reviewed the conventional and advance application of Ti sheet. The presence of small amounts of impurities such as nitrogen, carbon and hydrogen in which are soluble in the metal, causes the mineral fragility of the metal and prevents its commercial exploitation. The purpose of this study is to introduce and application of titanium in various industries. The main use of titanium in the industry is in the form of metal and titanium dioxide nanoparticles, the use of metal is not used much due to problems in its preparation and purification, but instead, the use of oxide in the form of TiO2 is widely used in industry. Therefore, 90% of the primary industries are consuming titanium oxide. The human body easily accepts titanium because it has been proven to be more biocompatible than stainless steel or cobalt chromium (CoCr). In addition, titanium has a higher fatigue strength than many other metals which helps to transform it as a desired material in orthopedic and dentistry applications. پرونده مقاله
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