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Topic Review
Nanojoining
Nanojoining is the process of joining two or more surfaces together using nanomaterials as the primary building blocks. This includes, but is not limited to, nanosoldering, nanobrazing, nanowelding, nanoscale diffusion bonding, and additive manufacturing. Note that, like with conventional soldering and brazing, only the filler metal undergoes melting, not the base material. Nanomaterials are materials in which at least one dimension 100 nm or less and include 0-D (e.g. nanoparticles, 1-D (e.g. nanowires and nanorods), 2-D (e.g. graphene), and 3-D (e.g. nanofoam) materials. Nanomaterials exhibit several notable properties that allow joining to occur at temperatures lower than the melting temperature of their bulk counterpart. For example, the melting temperature of Ag is 961.78 °C, but Ag nanomaterials begin to melt at a much lower temperature that is dependent depending on the size and shape. These properties include high surface area to volume ratio, the Gibbs-Thompson effect, and high surface energy. The low joining temperature of nanomaterials has been exploited numerous times for flexible electronics, printable electronics, and soldering applications; only within the last two decades have they been explored for high-temperature joining applications (>450 °C).
  • 704
  • 07 Jul 2022
Topic Review
Applications of Magnesium and Alloys
Since its discovery, magnesium has played an influential role in society. In its early days, military applications and wars fueled its growth. For example, magnesium was weaponized to construct incendiary bombs, flares, and ammunitions that were subsequently deployed in World War II, and it caused massive conflagrations and widespread devastations. Post-War, magnesium’s availability and unique blend of properties were explored and were found to be highly attractive for an extensive range of applications. Today, magnesium is used for engineering applications in automotive, aerospace, and consumer electronics. In addition, it has a role in organic chemistry and pharmaceuticals and is used to construct several general-purpose applications, such as sporting goods, household products, and office equipment.
  • 567
  • 09 Oct 2021
Topic Review
Additive Manufacturing of High Entropy Alloys
Alloying has been very common practice in materials engineering to fabricate metals of desirable properties for specific applications. Traditionally, a small amount of the desired material is added to the principal metal. However, a new alloying technique emerged in 2004 with the concept of adding several principal elements in or near equi-atomic concentrations. These are popularly known as high entropy alloys (HEAs) which can have a wide composition range.
  • 565
  • 15 Mar 2022
Topic Review
Turbulence Simulation Approaches
Turbulent flow can be numerically resolved with different levels of accuracy. Many numerical approaches for solving turbulence have been proposed, such as the Reynolds-Averaged Navier–Stokes (RANS), the Large Eddy Simulation (LES), and Direct Numerical Simulation (DNS) approaches. Among these numerical methods, the RANS approach, specifically the Eddy Viscosity Model (EVM), is widely used for calculating turbulent flows thanks to its relatively high accuracy in predicting the mean flow features and its more limited computational demands. However, this approach suffers from several weaknesses, e.g., compromised accuracy and uncertainties due to assumptions in the model construction and insufficient incorporation of the fluid physics. In the LES approach, the whole eddy range is separated into two parts, namely, the large-scale eddy and subgrid-scale (SGS) eddy. The former can be directly resolved, while the latter is computed using the SGS model. As the computing power rapidly increases, this approach is extensively used to study turbulence physics and to resolve low-to-medium Reynolds number flows.
  • 525
  • 13 Sep 2021
Topic Review
Hydrogen Embrittlement of Medium-Mn Steels
Recent research efforts to develop advanced–/ultrahigh–strength medium-Mn steels have led to the development of a variety of alloying concepts, thermo-mechanical processing routes, and microstructural variants for these steel grades. However, certain grades of advanced–/ultrahigh–strength steels (A/UHSS) are known to be highly susceptible to hydrogen embrittlement, due to their high strength levels. Hydrogen embrittlement characteristics of medium–Mn steels are less understood compared to other classes of A/UHSS, such as high Mn twinning–induced plasticity steel, because of the relatively short history of the development of this steel class and the complex nature of multiphase, fine-grained microstructures that are present in medium–Mn steels. The motivation of this paper is to review the current understanding of the hydrogen embrittlement characteristics of medium or intermediate Mn (4 to 15 wt pct) multiphase steels and to address various alloying and processing strategies that are available to enhance the hydrogen-resistance of these steel grades.
  • 486
  • 04 Nov 2021
Topic Review
Metallurgy/Weldability of High-Strength Cold-Resistant and Cryogenic Steels
Thermomechanical Controlled Processing (TMCP), the initial microstructure and mechanical properties of rolled products made of high-strength steels, have a significant influence on the properties and reliability of welded structures for low temperature and cryogenic service.
  • 443
  • 13 Dec 2021
Topic Review
Void Nucleation in Metals
The research discussed about the development of micro-voids in metals, leading to ductile fracture, associated with plastic deformation, without taking into account the cleavage mechanism. Particular emphasis was placed on the results of observations and experimental studies, the characteristics of the phenomenon itself, without in-depth analysis in the field of widely used FEM modelling. The mechanism of void development as a fracture mechanism is presented. Observations of the nucleation of voids in metals from the turn of the 1950s and 1960s to the present day have been described. The nucleation mechanisms related to the defects of the crystal lattice as well as those resulting from the presence of second phase particles were characterised.
  • 435
  • 08 Oct 2022
Topic Review
Properties of Wire Arc-Sprayed Fe-Based Coatings
Among different thermal spraying methods, arc-spraying has been widely used due to its low operating costs and high deposition efficiency. The rapid progress of cored wire technology in arc-spraying has increased possibilities for the preparation of new Fe-based coating materials with enhanced properties by adding reinforcement particles and alloying elements to suit the different applications. 
  • 412
  • 09 Mar 2022
Topic Review
China Intelligent Manufacturing Technology in the Steel Industry
Intelligent manufacturing, defined as the integration of manufacturing with modern information technologies such as 5G, digitalization, networking, and intelligence, has grown in popularity as a means of boosting the productivity, intelligence, and flexibility of traditional manufacturing processes. The steel industry is a necessary support for modern life and economic development, and the Chinese steel industry’s capacity has expanded to roughly half of global production.
  • 343
  • 03 Nov 2022
Topic Review
Abrasive Wear of Cermets
Abrasive wear occurs when hard particles or sometimes hard protuberances on a counterface are forced against and are moved along the surface. The amount of material removed depends on the normal load pressing particles against the surface and the sliding distance. A distinction is usually made between the two-body and the three-body abrasive wear and between low-stress (abrasive particles remain unbroken during abrasion) and high-stress (abrasive particles are broken during the wear process) abrasion. WC-based hardmetals (cemented carbides) are employed widely as wear-resistant ceramic-metal composites for tools and wear parts. Raw materials supply, environmental concerns and some limitations of hardmetals have directed efforts toward development of alternative wear-resistant composites-cermets. Cermets consist primarily of ceramic particles such as titanium carbonitride (Ti(C,N)), titanium carbide (TiC), and chromium carbide (Cr3C2) bonded with alloys of Ni, Co or Fe. Cermets as resistant to abrasive wear materials demonstrate their potential mainly in environmentally severe wear conditions – at elevated temperatures and corrosive envronments.
  • 341
  • 10 Jan 2022
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