Topic Review
Electric Arc Furnace Slag
EAF slag is a non-metallic by-product that consists mainly of silicates and oxides formed during the process of refining the molten steel. Raw EAF slag often appears as grey or black colored lumps, depending on its ferrous oxide content. This type of slag generally has a rough surface texture, with a surface pore diameter of 0.01–10 μm.
  • 9.2K
  • 26 Oct 2020
Topic Review
Microstructure of Ni-Based Superalloy
To understand the behaviour of the especially complex Ni-based superalloys at high-homologous temperatures it is necessary to characterize their microstructure in fully heat-treatment condition. Detection and characterization of precipitates even nano-precipitates is essential in the study of creep and fatigue degradation. Without the knowledge about the phase composition of material, it is problematic to predict the microstructure evolution during long-term service. The main aim of this work was to perform the comprehensive characterization of equiaxed Ni-based superalloy René 108 from micro- to atomic-scale resolution by using analytical microscopy techniques.    
  • 7.7K
  • 20 Dec 2020
Topic Review
Roasting Processes for Lithium Extraction
This entry describes the main thermal treatments for processing spodumene in order to get easier lithium extraction by hydrometallurgical routes. It shows the importance of the thermal treatment and the need to reduce the energy consumption of this operation.
  • 7.2K
  • 18 Nov 2020
Topic Review
Metal Oxide Applications
Metal oxides play a key role in environmental remediation.
  • 5.8K
  • 08 Dec 2020
Topic Review
Deep Cryogenic Treatment
Deep cryogenic treatment (DCT) is a type of cryogenic treatment, where a metallic material is subjected to temperatures below -150°C, normally to temperatures of liquid nitrogen (-196 °C). When a material is exposed to DCT as a part of heat treatment, changes in microstructure are induced due to new grain formation, changes in grain size, change in the solubility of atoms, movement of dislocations, alteration of crystal structure, and finally new phase formation. The metallic material's performance and later performance of manufactured components and tools from this specific material are dependent on the selection of proper design, proper material, accuracy with which the tool is made and application of proper heat treatment, including any eventual DCT. Metallic materials are ferrous and non-ferrous metals. In the last years ferrous metals (different grades of steel) and non-ferrous alloys (aluminum, magnesium, titanium, nickel etc.) have been increasingly treated with DCT to alter their properties. DCT treatment has shown to reduce density of defects in crystal structure, increase wear resistance of material, increase hardness, improve toughness, and reduce tensile strength and corrosion resistance. However, some researchers also reported results showing no change in properties (toughness, hardness, corrosion resistance, etc.) or even deterioration when subjected to DCT treatment. This leads to a lack of consistency and reliability of the treatment process, which is needed for successful application in industry. This review provides a synopsis of DCT usage and resulting effects on treated materials used in automotive industry.
  • 5.6K
  • 29 Oct 2020
Topic Review
Laser Powder Bed Fusion
Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. The reuse of the powder feedstock is crucial to make the process cost-efficient and environmentally friendly. However, since studies of the mechanical and microstructural properties of parts produced with reused powders show scattered results, a closer look to the powder, heat source and shielding gas properties and to how they interact during the LPBF process is presented.  
  • 3.9K
  • 29 Oct 2020
Topic Review
High-Temperature Shape Memory Alloys
With the aim to improve the strength of high-temperature shape memory alloys, multi-component alloys, including medium- and high-entropy alloys, have been investigated and proposed as new structural materials. Notably, it was discovered that the martensitic transformation temperature could be controlled through a combination of the constituent elements and alloys with high austenite finish temperatures above 500 °C. The irrecoverable strain decreased in the multi-component alloys compared with the ternary alloys. The repeated thermal cyclic test was effective toward obtaining perfect strain recoveries in multi-component alloys, which could be good candidates for high-temperature shape memory alloys.
  • 3.2K
  • 26 Nov 2020
Topic Review
Metal Matrix Composites
Metal matrix composites (MMCs) present extraordinary characteristics, including high wear resistance, excellent operational properties at elevated temperature, and better chemical inertness as compared to traditional alloys. These properties make them prospective candidates in the fields of aerospace, automotive, heavy goods vehicles, electrical, and biomedical industries. MMCs are challenging to process via traditional manufacturing techniques, requiring high cost and energy. The laser-melting deposition (LMD) has recently been used to manufacture MMCs via rapid prototyping, thus, solving these drawbacks. Besides the benefits mentioned above, the issues such as lower ultimate tensile strength, yield strength, weak bonding between matrix and reinforcements, and cracking are still prevalent in parts produced by LMD. In this article, a detailed analysis is made on the MMCs manufactured via LMD. An illustration is presented on the LMD working principle, its classification, and dependent and independent process parameters. Moreover, a brief comparison between the wire and powder-based LMDs has been summarized. Ex- and in-situ MMCs and their preparation techniques are discussed. Besides this, various matrices available for MMCs manufacturing, properties of MMCs after printing, possible complications and future research directions are reviewed and summarized.
  • 3.0K
  • 18 May 2021
Topic Review
Additive Manufacturing and Industry 4.0
We present a review on Additive Manufacturing and Industry 4.0 from business innovation and sustainability perspective.
  • 2.9K
  • 14 Apr 2021
Topic Review
Medium-Entropy Alloy
The objective of this study is to strengthen the FCC structued medium-entropy alloy using the hard carbides.
  • 2.8K
  • 26 Aug 2020
Topic Review
Semiconductor Gas Sensors
Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing.
  • 2.8K
  • 10 Dec 2020
Topic Review
Nickel-Copper Alloys
Nickel-Copper (Ni-Cu) alloys exhibit simultaneously high strength and toughness (particularly, at cryogenic temperatures), excellent corrosion resistance, and may show good wear resistance. Therefore, they are widely used for manufacturing of (i) structural components of equipment in the chemical, oil, and marine industries, (ii) resistors and contacts in electrical and electronic equipment, (iii) corrosion resistant coatings, and (iv) fuel cells. Processing technologies includes bar forging, plate and tube rolling, wire drawing, heat treatment (for certain alloy compositions), powder and wire arc additive manufacturing, electrodeposition.
  • 2.6K
  • 26 Oct 2020
Topic Review
Twinning-Induced Plasticity
Twinning-induced plasticity (TWIP) steel is a second-generation advanced high strength steel grade developed for automotive applications. TWIP steels exhibit an excellent combination of strength and ductility, mainly originating from the activation of deformation twinning.
  • 2.5K
  • 23 Feb 2021
Topic Review
Titanium Aluminides
Titanium aluminides (TiAl) have the potential of substituting nickel-based superalloys (NBSAs) in the aerospace industries owing to their lightweight, good mechanical and oxidation properties. Functional simplicity, control of sintering parameters, exceptional sintering speeds, high reproducibility, consistency and safety are the main benefits of spark plasma sintering (SPS) over conventional methods. Though TiAl exhibit excellent high temperature properties, SPS has been employed to improve on the poor ductility at room temperature. Powder metallurgical processing techniques used to promote the formation of refined, homogeneous and contaminant-free structures, favouring improvements in ductility and other properties are discussed. This article further reviews published work on phase constituents, microstructures, alloy developments and mechanical properties of TiAl alloys produced by SPS. Finally, an overview of challenges in as far as the implementation of TiAl in industries of interest are highlighted.
  • 2.1K
  • 07 Jan 2021
Topic Review
Ironmaking Process
Fe is extracted from Fe ore and converted into alloys. This metallurgical process is important. The raw materials of the iron-bearing mineral are introduced in the blast furnace (BF), wherein aside from Fe and C, other elements are also subjected to roasting in the furnace.
  • 2.0K
  • 10 Mar 2021
Topic Review
Super Duplex Stainless Steel
In this present study, the influence of isothermal aging temperature and duration on microstructural and mechanical properties of a hot-deformed UNS S32750 Super Duplex Stainless Steel (SDSS) alloy was investigated by SEM-EBSD (Scanning Electron Microscopy-Electron Backscatter Diffraction) and tensile testing techniques. An isothermal aging treatment, at temperatures between (400 - 600)°C and treatment duration between (3 - 120)h, was applied to a commercial UNS S32750 SDSS alloy. Microstructural characteristics of all thermo-mechanical (TM) processed states, such as distribution and morphology of constituent phases, grain’s modal orientation (MO) and, obtained mechanical properties were analysed correlated with the TM processing conditions. Obtained experimental results show that the constituent phases, in all TM processed states, are represented by delta- and gamma-phases. SEM-EBSD analysis revealed microstructural modifications induced by TM processing, showing elongated gamma-phase grains within delta-phase matrix. Within the delta-phase matrix, dynamically recrystallized grains were identified as a result of applying hot deformation and isothermal aging treatments. Also, it was observed that aging treatment parameters can significantly influence the mechanical behaviour exhibited by the UNS S32750 SDSS alloy, in terms of elongation to fracture and absorbed energy during impact testing.
  • 2.0K
  • 29 Oct 2020
Topic Review
TIG-MIG Hybrid Welding
Tungsten inert gas-metal inert gas hybrid welding (TIG-MIG) combines the advantages of tungsten and metal inert gas welding. It can efficiently produce high-quality weld joints that meet modern manufacturing quality and efficiency requirements. Based on heat transfer, fluid dynamics, and electromagnetic theory, a three-dimensional coupled transient model of arc-droplet interactions in TIG-MIG hybrid welding was established. In this study, the temperature field, flow field, electromagnetic force, pressure, and current density parameters were analyzed in the arc space. The results show that introducing TIG welding has a significant impact on MIG welding.
  • 1.8K
  • 13 Jan 2021
Topic Review
Intermediate Strain Rate Testing Devices
The existing experimental tests are mainly designed to study the mechanical response of materials at various strain rates. Many researchers performed the experimental test in tension, compression, and shear (with torsion test) over a wide range of strain rates. They found out that material exhibits an increase in yield stress as well as flows stress with an increase in strain rate. It illustrates that there is a need for experimental data to study the material behaviour over the full range of strain rates, from quasi-static to high strain rate test. Many special techniques have been developed to bridge the strain rate gap between quasi-static and high strain rate testing to provide a method for an intermediate strain rate test for engineering materials. Some researchers have tried to conduct intermediate strain rate tests with standard servo-hydraulic load frames. However, the results of such tests are not accurate. The problem is that during the experiment, the whole machine is not in static equilibrium. The inertial effect influences the experimental data. The records obtained from these machines are often noisy with large oscillation. therefore, the comprehensive review is given to describes the development and evolution of the existing intermediate strain rate testing devices which includes the working principles, some critical theories, technological innovation in load measurement techniques, components of the device, basic technical assumption, and measuring techniques. In addition, some research direction on future implementation and development of an intermediate strain rate apparatus is also discussed in detail.
  • 1.8K
  • 18 Apr 2021
Topic Review
Fe-Based Magnetic Amorphous Alloys
Amorphous alloys for soft magnetic applications are often fabricated by rapid solidification of the melt. They are generally prepared with the nearly 20% addition of metalloids (Si, B, Al, C and P) for Fe-based and Co-based alloys. Si and B are important metalloids for glass formation and the amorphous structure stabilisation. Typical chemical compositions are such that the combined compositions of Fe, Co, Ni elements are 70–85 atomic (at.)% and those of Si and B are 15–30 at.% in total. However, magnetic glassy alloys have a wide variety of compositions. This allows for a large range of soft magnetic properties to be achieved, which depend upon the demands of the application.
  • 1.6K
  • 28 Apr 2021
Topic Review
Microalloyed Niobium Steel
Thermomechanical processing of niobium microalloyed steel was performed with the purpose of determining the interaction between niobium precipitates and dislocations, as well as determining the influence of the temperature of final deformation on the degree of precipitation and dislocation density. Two variants of thermomechanical processing with di erent final rolling temperatures were carried out. Samples were studied using electrochemical isolation with an atomic absorption spectrometer, transmission electron microscopy, X-ray di raction analysis, and universal tensile testing with a thermographic camera. The results show that the increase in the density of dislocations before the onset of intense precipitation is insignificant because the recrystallization process takes place simultaneously. It increases with the onset of strain-induced precipitation. It is shown that niobium precipitates determine the density of dislocations. The appearance of Lüders bands was noticed as a consequence of the interaction between niobium precipitates and dislocations during the subsequent cold deformation. In both variants of the industrial process performed on the cold deformed strip, Lüders bands appeared.
  • 1.4K
  • 26 Oct 2020
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