Subjects -> METALLURGY (Total: 58 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access  
Advanced Device Materials     Open Access   (Followers: 3)
American Journal of Fluid Dynamics     Open Access   (Followers: 47)
Archives of Metallurgy and Materials     Open Access   (Followers: 8)
Asian Journal of Materials Science     Open Access   (Followers: 5)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 20)
Complex Metals     Open Access   (Followers: 1)
Corrosion Communications     Open Access   (Followers: 5)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 10)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 3)
International Journal of Metals     Open Access   (Followers: 6)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 8)
International Journal of Mining and Geo-Engineering     Open Access  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 4)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 23)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 32)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 7)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 1)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 18)
Journal of Metallurgical Engineering     Open Access   (Followers: 2)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Engineering     Open Access  
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 31)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 6)
Metallurgy and Foundry Engineering     Open Access  
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 33)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Rare Metals     Hybrid Journal   (Followers: 1)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access  
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 4)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 1)
Stainless Steel World     Full-text available via subscription   (Followers: 17)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 4)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 1)
Welding in the World     Hybrid Journal   (Followers: 4)
Welding International     Hybrid Journal   (Followers: 7)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Transactions of the Indian Institute of Metals
Journal Prestige (SJR): 0.361
Citation Impact (citeScore): 1
Number of Followers: 4  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0972-2815 - ISSN (Online) 0975-1645
Published by Springer-Verlag Homepage  [2469 journals]
  • Characterization of the Welding Zone of Automotive Sheets of Different
           Thickness (DP600 and DP800) Joined by Resistance Spot Welding

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      Abstract: Automotive industry in recent years, has gained great importance. In line with this, DP600 and DP800 dual-phase steels and the electrical resistance spot welding method were used in the study. During the experimental trials, different welding currents (6, 7, and 8 kA) were selected and all other welding parameters were kept constant. The effects of the welding parameters on microstructure, hardness, tensile-shear, and cross-tensile strength were analyzed. In the phase measurements, 27.06–29.97% martensite and 70.73–73.85% ferrite phases were found. When the hardness values in the HAZ regions were examined, it was seen that the highest hardness values were 356 ± 5 HV in the DP600 and 451 ± 5 HV in the DP800 with a current intensity of 6 kA. Consequently, it was determined that tensile-shear and cross-tensile strengths had increased in parallel with the increase in the welding current and the highest values were determined as 8 kA–15.91 kN in tensile shear and 8 kA–4.91 kN in cross-tensile strength.
      PubDate: 2022-01-21
       
  • Optimization of Process Parameters in Double-Pulse MIG Welding of Inconel
           617-SS 304 H

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      Abstract: Objectives In this study, an effort is made to predict the optimized parameter combination in double-pulse MIG welding of stainless steel (SS 304H)—Inconel 617 (IN 617) Methods Butt joints were made between IN 617 and SS 304H using ER308 H filler wire having a diameter of 1.2 mm. Welding trials were done based on Taguchi L9 array with wire feed speed, frequency and amplitude as input parameters. The weld quality was evaluated by measuring bead width, depth of penetration, tensile strength and impact strength. The optimized parameter combination was identified using two multiobjective techniques, viz. grey relational analysis (GRA) and technique for order of preference by similarity to ideal solution (TOPSIS). Conclusions GRA and TOPSIS gave similar results with regard to optimized parameter combinations. Analysis of variance (ANOVA) was applied to find the most influential parameter on weld quality. From ANOVA, the amplitude was identified as the most influential parameter. The presence of M23C6 and M6C precipitates in the fusion zone helped in strengthening the weld. At higher wire feed speed, lack of side wall fusion was noted on the SS 304H side of the weld.
      PubDate: 2022-01-21
       
  • Optimal Control of Surface Crack in Microalloyed Steel with Big Stroke
           Liquid Core Reduction Process

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      Abstract: In this paper, a new idea of optimizing and improving the surface crack of microalloyed steel slab by using big stroke liquid core reduction (B-LCR) process was studied and analyzed by combining numerical simulation with industrial test. The results show that the stress–strain distribution is different in different parts of the slab during liquid core reduction; the stress at the corner of the slab is the largest, and the stress at the wide surface is greater than that at the narrow surface. When the total reduction is increased to 35 mm by using B-LCR process, the equivalent strain on the interior of the slab is 0.566%. It is consistent with the maximum additional strain value (calculated value) of 0.552% on the center of the slab, and no pressure crack will occur. The industrial test results show that B-LCR process can improve the internal and surface quality of low content alloying element steel obviously. But with the gradual increase in microalloying element content, B-LCR process cannot completely solve the surface crack defect. It can only play a role in reducing defects.
      PubDate: 2022-01-19
       
  • Optimization of Column Flotation for Fine Coal Using Taguchi Method

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      Abstract: The efficacy of column flotation in producing low-ash clean coal for the metallurgical industries is explored in this work. The effect of four critical operating parameters such as collector dosage (A), frother dosage (B), superficial velocities of air (C) and wash water (D) on the combustibles recovery (CR) and ash rejection (AR) was studied. Experiments were carried out based on the Taguchi orthogonal array of experimental design ( \(L_{9} OA\) ), and the signal-to-noise (S/N) ratios were calculated for both the responses. In this study, the principal parameters, their rank on the responses and the optimum conditions to maximize the responses were also identified. Column flotation produced clean coal with combustibles recovery in the range of 66.94–80.04%, while keeping the ash rejection in the range of 55.91–73.83%. Regression models were developed to predict the separation efficiency, ash rejection and combustible recovery in the column flotation, and the average error in prediction of the separation efficiency was ± 6%.
      PubDate: 2022-01-19
       
  • The Improvement in Mechanical Properties and Strengthening Mechanism of
           The New Type of Cast Aluminum Alloy with Low Silicon Content for
           Automotive Purposes

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      Abstract: The effects of different Si and Cr contents on the microstructure and mechanical properties of new type aluminum alloy with low silicon content were studied by means of hardness test, tensile test and metallographic preparation, SEM, EDS and DSC. The results showed that when the Si content increased gradually, the hardness and tensile strength increased first and then decreased. When the Si content was 3.5%, the hardness and tensile strength reached the maximum. The microstructure observation showed that when the Si content was 3.5%, the microstructure was the most fine and dense, and the secondary dendrite arm spacing (SDAS) of the alloy had the minimum value. When the content of Cr element increased gradually, the tensile strength and elongation showed a trend of increasing gradually, and the maximum value was obtained at 0.5%. When Si was 3.5% and Cr was 0.5%, the best mechanical properties were obtained. At this time, the microstructure of the alloy was fine, dense and uniform, and Mg2Si strengthening phase was precipitated during heat treatment. Cr element has the functions of solid solution, fine crystal and dispersion strengthening. Therefore, the tensile strength, yield strength and elongation of the new aluminum alloy were 350.7 MPa, 303.0 MPa and 8.56%, which has obvious advantages over the traditional cast Al-Si alloy.
      PubDate: 2022-01-18
       
  • Characterization for Identification of Possible Beneficiation Strategies
           for Low-Grade PGE Ores from Mesoarchean Boula-Nuasahi Igneous Complex,
           Singhbhum Craton, India

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      Abstract: Comprehensive characterization studies are carried out to develop a suitable beneficiation process for treating low-grade platinum group elements (PGEs) ore from Mesoarchean Boula-Nuasahi Igneous Complex in southern part of Singhbhum Craton, eastern India. The PGE mineralization is magmatic and hydrothermal in origin and found in association with NNW–SSE-trending mafic–ultramafic igneous rocks in the tectonic brecciated zone toward the eastern part of the complex. The PGE-bearing minerals are very fine grained (< 1–50 µ) and exhibit heterogeneous distribution, with a total grade of 2.094 g/t. Chalcopyrite, pyrrhotite, pentlandite, pyrite, etc. are found as discriminate grains while the altered silicates (tremolite, riebeckite, enstatite, etc.) are the main gangue minerals present in this ore. The common PGE minerals, such as sperrylite, sudburyite, braggite, laurite, and testibiopalladite, are identified, and individual elemental distribution is analyzed by electron probe micro-analyzer mapping. Based on the studies, different flow schemes are proposed and discussed.
      PubDate: 2022-01-17
       
  • CO2 Emission of CO2 Injection into Blast Furnace

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      Abstract: As an energy-intensive industry, the iron and steel industry has been facing the challenges associated with reducing CO2 emissions. Therefore, metallurgical workers have been examining whether the steel industry can absorb some of the CO2 emissions. At high temperatures, CO2 is capable of oxidizing, which can lead to reactions with the carbon in the tuyeres raceway of the blast furnace to generate twice the volume of CO, improving the degree of indirect reduction and increasing the CO concentration in the top gas. In this study, metallurgical thermodynamics is used as the basis for constructing mathematical models of the mass and energy balance of a blast furnace and of the heat balance of a hot blast stove. Based on these models, the CO2 emission of CO2 injection into blast furnace is analyzed using the blast furnace CO2 emission model. Because of the endothermic reaction between CO2 and carbon, thermal compensation for the increases in the fuel ratio and oxygen enrichment is required. As the CO2 enrichment rate increases, the input of CO2 emission increases. However, as the CO concentration in the top gas increases and the top gas required by the hot blast stove decreases, the CO2 emission reduction at the output increases. When the CO2 enrichment limit is reached, the CO2 emission at the input increases by 530.97 kg/(tHM), the CO2 emission reduction at the output increases by 544.65 kg/(tHM), and the net CO2 emission decreases by 13.68 kg/(tHM). The high-quality top gas can replace a portion of the role of gas producers and reduce the CO2 emission of gas producers by 38.84 kg/(tHM). It can also prevent too much low-quality top gas from being released.
      PubDate: 2022-01-17
       
  • Effects of Metal and Inorganic Additives on the Tribological Performances
           of Nickel-Based Composites with Rice Husk Ceramic Particles

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      Abstract: Rice husk ceramic (RHC) can be used as a reinforcing agent in metal matrix composites (MMC) to improve the tribological properties because of their remarkable mechanical and tribological properties. This research scrutinizes the role of RHC to enhance tribological properties of Ni-MMC (Nickel metal matrix composite). Ni-MMC with additives RHC, Al, Cu, MoS2, and graphite in different content were prepared by powder metallurgy method. The wear and friction mechanism of Ni-MMC was investigated using a ball-disk tribometer at room temperature. SEM/EDS and optical microscope were used to examine the wear properties, distribution of reinforcement, and micro structural phases, respectively. Results indicated that the addition of RHC particles can strengthen the anti-wear and friction reduction properties of Ni-MMC. The addition of 3 wt% RHC resulted in the lowest value for the coefficient of friction and wear rate. Further expansion of MoS2 and graphite along 3 wt% RHC, both the wear rate and coefficient of friction all decrease. At the same time, the value depends on the content of elements like aluminum and copper in MMCs.
      PubDate: 2022-01-17
       
  • A Study on the Suitability of Mahanadi Riverbed Sand as an Alternative to
           Silica Sand for Indian Foundry Industries

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      Abstract: The availability of silica sand is diminishing and as a result, the price of silica sand increasing. Therefore, there is a need to evaluate the suitability of local riverbed sand for nonferrous alloy casting in Indian foundries. The present investigation focuses on the suitability of Mahanadi Riverbed Sand (MRS) for nonferrous alloy casting. The sand particle size, chemical composition, density, and fusion point, are evaluated and found suitable for nonferrous alloy casting. The mold ingredients are designed and optimized through the design of the experiment and response surface methodology, respectively. It is found that 11.5 wt.% of bentonite clay, 5 wt.% of moisture, and 3.5 wt.% of coal dust is suitable to achieve the desire sand mold properties. The fusion point of MRS shows that it is not suitable for ferrous casting. Therefore, aluminum alloy (A356) casting is performed using MRS and silica sand mold. The as-cast surface roughness (Ra), hardness, and microstructures of A356 alloy casting are evaluated and compared between MRS and silica sand mold castings. It is observed that the mechanical properties of MRS mold casting are better than silica sand mold casting and may be used as an alternative to silica sand for aluminum alloy casting in Indian foundry industries.
      PubDate: 2022-01-16
       
  • Effect of Aging Temperature on Microstructure and Tensile Properties of
           Inconel 718 Fabricated by Selective Laser Melting

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      Abstract: Inconel 718 superalloy was prepared by selective laser melting. The microstructure, precipitated phase and tensile properties of Inconel 718 at different aging temperatures were tested by optical microscope, scanning electron microscopy and tensile testing machine. The results show that Inconel 718 alloy has fewer defects and higher density. With the increase of aging temperature, the δ phase gradually dissolves and the grains coarsen gradually. Compared with 650 °C, the strain hardening rate of the material increases when the aging temperature reaches 750 °C, the tensile strength can reach 1410.94 MPa, and the precipitation strengthening of γ" phase plays a dominant role. When the tagging emperature exceeds 750 °C, the strain hardening rate of the material is further increased and the solid solution strengthening effect is gradually enhanced.
      PubDate: 2022-01-16
       
  • Effect of Nano-ZrO $$_2$$ 2 Additions on Fabrication of ZrO $$_2$$ 2 /ZE41
           Surface Composites by Friction Stir Processing

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      Abstract: Friction stir processing (FSP) technique was used to fabricate surface metal matrix composites of the newly commercialized ZE41-rare earth magnesium alloy (in cast form) using nano-ZrO \(_2\) reinforcement particles. The volume percentage of reinforcement particles was varied as 4N \(\%\) (where N \(\in \) [1,2,3,4]) in the matrix. The results of microstructural examinations revealed the refinement of grains from 113 to 0.7 µm. The intermetallic compound (Mg \(_7\) Zn \(_3\) RE) present at the grain boundaries was seen to be distributed as particles after FSP suggesting the formation of fine grains. The presence of reinforcement particles and evolution of fine grains at the stir zone leads to increase in mechanical properties of fabricated composites. The microhardness was seen increased from 70 HV (ZE41) to 119 HV (ZE41-16 \(\%\) ZrO \(_2\) MMC). The tensile strength was observed to be increased from 154.5 MPa (ZE41) to 195.5 MPa (ZE41-12 \(\%\) ZrO \(_2\) MMC). From the present study, it was learnt that the addition of nano-ZrO \(_2\) particles coupled with optimized FSP parameters led to the formation of defect-free nanocomposites with increased mechanical properties.
      PubDate: 2022-01-16
       
  • Thermoluminescence Characterization of Rare Earth-Doped Yttrium Stannate
           Phosphors Deposited by Friction Stir Processing

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      Abstract: The goal of this study is to examine the thermoluminescence (TL) properties of materials obtained by depositing rare earth ion-doped yttrium stannate (Y2Sn2O7) phosphor powders on metallic surfaces using friction stir technique. Y2Sn2O7 phosphors doped with Tb, Eu and Dy rare earth ions were produced by the solid-state reaction synthesis method by sintering at 1450 °C. TL properties of Y2Sn2O7:Eu, Dy and Tb were examined under X-ray irradiation, UV radiation (254 nm) and beta radiation. Thermoluminescence dosimeter (TLD) reader was used for recording the TL glow curves, and linear heating rate was selected as 2 Ks−1. The thermoluminescence glow curves of deposited phosphors showed prominent glow peaks at 225 °C for Y2Sn2O7:Tb, 185 °C and 295 °C for Y2Sn2O7:Eu and 150 and 260 °C for Y2Sn2O7:Dy after irradiated with X-ray radiation. TL properties of phosphor composites deposited by friction stir processing are a pioneering study.
      PubDate: 2022-01-15
       
  • Electrowinning of Nickel and Cobalt from Non-circulated Sulfate
           Electrolyte

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      Abstract: A laboratory investigation on nickel and cobalt electrowinning procedure from dilute synthetic sulfate-based electrolytes (with concentrations less than 40 gr/l) in a non-circulating apparatus has been carried out in the presence of boric acid as a buffering agent. By perusing previous studies on the same subject, five levels were identified for the parameters, including initial pH, temperature, and current density. Experiments were carried out in two time groups. Deposit morphology, current efficiency, and specific energy consumption were discussed as the outcomes of the process. The results produced evidence that favorable conditions (low power consumption, appropriate deposit quality, and high efficiencies) were reached at 400 A/m2, 55 °C and initial pH 5 for nickel and at 600 A/m2, 70 °C, and initial pH 5 for cobalt electrolysis. In addition, higher current efficiencies (lower power consumptions) widely occurred above 400 A/m2 in nickel electrowinning, while cobalt constraint regions of high efficiencies were observed at 200 A/m2 and 600 A/m2. Graphical abstract
      PubDate: 2022-01-15
       
  • Synthesis and Stability of Higher-Order Superstructure of Cubic Laves
           Phase in an Al-Cu-Ta alloy

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      Abstract: In this work, we investigated on the synthesis and stability of a ternary complex metallic alloy in Al-Cu-Ta system, close to the composition of Al56.6Cu3.9Ta39.5. The Rietveld refinement of X-ray diffraction data established its structure to be FCC (space group: F \(\overline{4 }\) 3m; lattice parameter, a = 45.339 (7) Å), which has been correlated with the seventh order superstructure (7x7x7) of imaginary cubic Laves phase (lattice parameter of it being close to 6.5 Å). After annealing at1400K for 24 h, the as-cast alloy exhibited the same type of intermetallic phase with the slightly reduced lattice parameter (a = 45.2908 (9)Å). However, no other major phases could be detected from the X-ray diffraction data in both the as-cast and annealed alloys. The microhardness tests showed a variation of hardness from 8.8 GPa to 7.2 GPa for annealed and 7.6 GPato 4.8 GPa for as-cast samples. The variation of hardness with load, known as indentation size effect, was found to be relatively less in the annealed sample compared to that of the as-cast one. No cracking is observed even at load of 1000 g implying the possibility of the limited toughness of this complex phase. Due to high hardness and high-temperature stability, this phase appears to have potential for applications as hard and tough coating materials.
      PubDate: 2022-01-15
       
  • A Review on Processing of Electric Arc Furnace Dust (EAFD) by
           Pyro-Metallurgical Processes

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      Abstract: In recent years, the recovery of the valuable metals from iron-bearing solid waste from steel plant has been one of the most intensive research areas. Dumping of electric arc furnace dust is an environmental concern, and recovery of valuable metals like iron, zinc, lead from EAFD and safe disposal of residue has got enough attention. Evolution of improved and new processes has motivated industries to engage actively and targeting the new and efficient methods to recycle EAFD. The presence of valuable elements and increasing cost of waste incorporation are the motivational factors for the recycling of EAFD. In this article, the technologies that are in use to process EAFD have been discussed, and their advantages and disadvantages are also highlighted.
      PubDate: 2022-01-14
       
  • Finite Element Analysis of Residual Stress Induced by Single-Pass
           Ultrasonic Surface Rolling Process

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      Abstract: The formation mechanism of residual stress field (RSF) and the coupling mechanisms of RSFs after single-pass ultrasonic surface rolling process (USRP) are revealed. Based on simulation, the transient evolution and steady distribution of compressive RSF are analyzed, and the influences of process parameters (i.e., the movement distance of the ball in a single period L, ball radius R, static force F and ultrasonic amplitude A) on residual stress (RS) after single-pass USRP are investigated. The results show that the plastic strain, which is induced by the extrusion of the target surface with the ball applying static force and ultrasonic vibration, causes compressive RS layer mainly. A new RSF will be induced simultaneously when the ball vibrates for a period, then the RSF induced by each period couples with several adjacent RSFs, and a compressive RS layer forms on the target surface finally. Furthermore, the surface compressive RS, the depth of maximum compressive RS and the depth of compressive RS layer increase effectively with the increase in F. Decreasing R can increase the surface compressive RS while decrease the depth of compressive RS layer slightly. Increasing A can increase the depth of compressive RS layer obviously when F is small, while has less influence on compressive RSF when F is large. For a relatively small L, the surface RS is compressive and achieves a uniform distribution.
      PubDate: 2022-01-13
       
  • Revisiting Quasicrystals for the Synthesis of 2D Metals

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      Abstract: Quasicrystals (QCs) are intermetallic materials with long-range ordering but with lack of periodicity. They have attracted much interest due to their interesting structural complexity, unusual physical properties, and varied potential applications. The last four decades of research have demonstrated the existence of different forms of QC composed of several metallic and non-metallic systems, which have already been exploited in several applications. Recently, with the experimental realization of 2D (atomically thin) metals, the potential applications of these structures have significantly increased (such as inflexible electronics, optoelectronics, electrocatalysis, strain sensors, nano-generators, innovative nano-electromechanical systems, and biomedical applications). As a result, high-quality 2D metals and alloys with engineered and tunable properties are in great demand. This review summarizes the recent advances in the synthesis of 2D single and few layered metals and alloys using quasicrystals. These structures present a large number of active sites for hydrogen evolution process catalysis and other functional properties. In this review, we also highlighted the possibility of using QC to synthesize other 2D metals and to explore their physical and chemical properties.
      PubDate: 2022-01-13
       
  • Influence of Shielding Gas Composition and Pulsed Current Frequency on the
           Microstructure of Austenitic Stainless Steel Welded by Pulsed Current GTAW
           

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      Abstract: In the current research, an attempt was made to study the effect of shielding gas composition and operational parameters on the microstructure of austenitic stainless steel. Fulfilling this purpose, a 4 mm austenitic stainless steel sheet was provided. Pulsed current gas tungsten arc welding was carried out using nitrogen gas with the volume percent of zero, 0.5, 1, 2, 5, and 10 in addition to argon as the shielding gas and under pulsed current with frequencies of 40, 80, 120, 160, and 200 Hz. After welding, samples were cut, and the metallographic study was done on weld metal by optical microscope and scanning electron microscope. Furthermore, a ferrite-scope test was performed on the weld metal, and the results were evaluated. Mechanical properties were investigated, and fracture surface was studied. Results showed that increasing the frequency of pulsed current leads to a decrease in ferrite amount in the microstructure, and the area fraction of ferrite decreased to 23% by increasing the frequency. Moreover, it was proven that the addition of nitrogen to the shielding gas resulted in an ascending change in the heat input in the weld pool. Also, with the increase in welding metal nitrogen, ferrite at frequencies of 40 and 200 Hz decreased to 56% and 62%, respectively. In addition, the morphology of the remaining ferrite transformed from mixed lacy-vermicular to completely vermicular. The hardness of the weld metal increased to 66% and 37% at the frequencies of 40 and 200 Hz, respectively. Similarly, the yield strength increased to 11% and 10% at similar frequencies. Graphical abstract
      PubDate: 2022-01-13
       
  • Microstructure and Mechanical and Oxidation Properties of Multilayer
           Aluminide Coatings Formed Over P91 Steel

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      Abstract: Iron aluminide-based oxidation-resistant and permeation barrier coatings were formed on P91 steel using pack cementation and post-coating annealing treatment. Fe2Al5 layers of variable thicknesses were formed at the coating temperatures in the range of 600–700 °C. The as-coated alloy annealed at 625–750 °C for different duration revealed the formation of multilayered coating structure that consisted of FeAl2, FeAl and Fe(Al) phases of varying thicknesses. Knoop hardness of Fe2Al5 phases was found to be 700 HK. High-resolution nanoindentation mappings were carried out for heat-treated specimen to establish structure–property interlink at the micron length scale. Hardness and modulus maps were generated using large numbers of arrays of nanoindentations at intervals of 2 µm. Scratch tests performed at varying loads revealed superior scratch resistance of FeAl as compared to Fe2Al5 phase. Oxidation studies under pure O2 environment of as-coated alloy in the temperature range of 700–1000 °C for 8 h revealed the parabolic growth of alumina scale.
      PubDate: 2022-01-12
       
  • Friction and Wear Characterization of Nanocomposites Based on Si3N4
           Reinforced with SiC, Mo, MoSi2 Nanoparticles

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      Abstract: Friction and wear behaviors of nanocomposites based on silicon nitride ceramics reinforced by silicon carbide, molybdenum or molybdenum disilicide were studied. The nanocomposite materials were prepared via spark plasma sintering. Tribological tests were carried out against silicon carbide balls under dry conditions by means of reciprocating ball-on-flat tribometer. The aim of this study is to determine the most efficient ceramic material for sliding applications while optimizing tribological parameters such as sliding velocity and normal load. Experimental results have shown that tribological behaviors of nanocomposite materials based on silicon nitride ceramics depend on reinforcement nanoparticles, normal load and sliding velocity. A friction coefficient of 0.4–0.9 as average values was obtained for the three composite materials under a frequency of 1 Hz–0.25 Hz; moreover, specific wear rate decreased as the frequency increased. The lower friction coefficient is noted for Si3N4-MoSi2, which is equal to 0.28 for 17 N as normal load, while the highest is noted for Si3N4-SiC and equal to 0.56 at 57 N as normal load.
      PubDate: 2022-01-11
       
 
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