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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.
  • 1.2K
  • 28 Apr 2021
Topic Review
AxBy Intermetallics for hydrogen storage
AxBy intermetallics show outstanding performances, notably for stationary hydrogen storage applications. Elemental substitution, whether on the A or B site of these alloys, allows the effective tailoring of key properties such as gravimetric density, equilibrium pressure, hysteresis and cyclic stability for instance.
  • 1.1K
  • 01 Feb 2021
Topic Review
Low-Temperature Hot Stamping Technologies
Improvement of the hot stamping process is important for reducing processing costs and improving the productivity and tensile properties of final components. One major approach to this has been to conduct all or part of the process at lower temperatures.
  • 1.0K
  • 23 Dec 2020
Topic Review Peer Reviewed
Exsolution Catalysts—Increasing Metal Efficiency
Exsolution catalysts are perovskite oxide-based materials that can exsolve catalytically active dopant elements as nanoparticles covering the surface, while the perovskite backbone can act as a stable support material. Thus, under proper conditions, a highly catalytically active and stable catalyst surface can be achieved. For many catalytic materials, precious metals or non-abundant elements play a key role in high catalytic activity. As these elements are often expensive or their supply is ecologically and ethically problematic, the replacement, or at the least reduction in the necessary amount used, is a common aim of current research. One strategy to do so is utilizing exsolution catalysts, as the active elements can be very selectively exsolved, and hence only very small doping amounts are sufficient for excellent results. This approach enables catalyst design with very high active metal efficiency.
  • 964
  • 13 Apr 2022
Topic Review
Interstitials in High Entropy Alloys
The effects of interstitials on the mechanical properties of single-phase f.c.c. high entropy alloys (HEAs) have been assessed based on a review of the literature. It is found that in nearly all studies, carbon increases the yield strength, in some cases by more than in traditional alloys. This suggests that carbon can be an excellent way to strengthen HEAs. This strength increase is related to the lattice expansion from the carbon. The effects on other mechanical behavior is mixed. Most studies show a slight reduction in ductility due to carbon, but a few show increases in ductility accompanying the yield strength increase. Similarly, some studies show little or modest increases in work-hardening rate (WHR) due to carbon, whereas a few show a substantial increase. These latter effects are due to changes in deformation mode. For both undoped and carbon doped CoCrFeMnNi, the room temperature ductility decreases slightly with decreasing grain size until ~2-5 µm, below which the ductility appears to decrease rapidly. The room temperature WHR also appears to decrease with decreasing grain size in both undoped and carbon-doped CoCrFeMnNi and in nitrogen-doped medium entropy alloy NiCoCr, and, at least for the undoped HEA, shows a sharp decrease at grain sizes <2 µm. Interestingly, carbon has been shown to almost double the Hall–Petch strengthening in CoCrFeMnNi, suggesting the segregation of carbon to the grain boundaries. There have been few studies on the effects of other interstitials such as boron, nitrogen and hydrogen.
  • 998
  • 06 Nov 2020
Topic Review
Rare Earth Elements Recovery
The manuscript covers the issues related to the characteristics, application, and some methods of rare earth elements (REEs) recovery from coal fly ashes. REEs are elements with growing demand and a very wide range of application, especially when it comes to modern technologies. The development of the REE recovery technology would involve solving several problems related to REE speciation, optimization of factors controlling their extractivity and selection of the REE separation method from obtained extraction solutions with a very extreme pH and complicated composition. The paper presented advantages and disadvantages of usually used methods of REE separation from coal fly ashes, like physical and acid–base leaching. It was also presented alternative REE recovery techniques in the form of membrane and biological methods and based on ion liquids (ILs) or chelating agents. The directions of further modifications, which will allow the efficient REE recovery were presented. The aim of this article was to propose specific solutions based on the creation of appropriate multistage method of REE recovery. It will be a combination of magnetic and size separation, acid–base leaching (including roasting in justified cases), removal of matrix elements with ILs (Al, Si, and Fe), and finally REE membrane separation, allowing one to obtain the appropriate process efficiency.  
  • 968
  • 29 Jan 2021
Topic Review
Al-Based Metal Foams
Metal Foams (MF) are tridimensional metal matrices which can be defined as mixtures of metal and gas (generally gas volume fraction is higher than 70% and relative density is lower than 0.3). MF can have open or closed cells, which means that porosity can be interconnected or not, respectively.  Metal foams are extremely interesting due to their low density, high specific stiffness, and impact energy/vibration absorption ability. The use of metal foams as permanent cores in casting can be an opportunity to improve the properties of cast components and to simplify the technological processes (e.g., no need for core removal/treatment/recycling). 
  • 855
  • 08 Jan 2021
Topic Review
External Human–Machine Interface of AVs
In future urban traffic, it is more likely that automated vehicles (AVs) will operate not in separated traffic spaces but in so-called mixed traffic environments where different types of traffic participants interact. Therefore, AVs must be able to communicate with other traffic participants, e.g., pedestrians as vulnerable road users (VRUs), to solve ambiguous traffic situations. Taking current traffic communication patterns into account, a combination of implicit communication via the driving behavior (e.g., deceleration, position in lane) and explicit communication via an external Human–Machine Interface (eHMI) seems to be a promising approach. The eHMI consists of an external interface connected to the vehicle, which can transmit explicit signals enabling interaction between AVs and other TPs.
  • 829
  • 15 Aug 2021
Topic Review
WAAM of Duplex Stainless Steels
WAAM (Wire and Arc Additive Manufacturing) is becoming an increasingly popular method to produce components from metals which are usually not so suitable for conventional production methods. One of the good examples is duplex stainless steels (DSS), which are quite complex for welding and machining. Excessive ferrite amount is a common problem for them and controlling an interlayer temperature could offer a solution. However, using too low interlayer temperature will slow down the whole process and compromise one of the WAAM’s main advantages - the high productivity. Aim of this study is to find the relationship between interlayer temperature and process duration and to determine the influence of the interlayer temperature on product structure and other properties. Three samples (walls) were made using different interlayer temperatures (50 °C, 100 °C and 150 °C) and they were tested to analyze their surface texture, chemical composition, ferrite amount, the appearance of porosity and the hardness. Ferrite amount was higher and there was more porosity on lower interlayer temperatures, while there is no significant difference between surface texture and chemical composition for the samples. Considering the fact that higher interlayer temperatures provide a faster process, they should be preferred to produce duplex stainless steel products.
  • 732
  • 16 Dec 2020
Topic Review
Rare Earth Metals
Rare earth elements are the general named of 17 special elements, containing lanthanide element, scandium and yttrium. They are commonly represented by RE. They have been widely applied in functional materials, steel and nonferrous metals due to its special optical, electrical and magnetic properties. 
  • 693
  • 09 Nov 2020
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