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Qi et al. [12] found that the refractory elements W and Mo are inherently brittle, but the transition metals of subgroup IV or V are inherently ductile. On the other hand, Sheikh et al. [13] reported that BCC-structured RHEAs consisting of subgroups IV, V and VI transition metals are intrinsically ductile if the valence electron concentration ...
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The digestion of rare earth and refractory elements is commonly achieved using hydrofluoric acid (HF) in combination with mineral acids, such as nitric acid (HNO 3), hydrochloric acid (HCl) and perchloric acid (HClO 4) . The HF is good on breaking up the silica matrix and to liberate all entrapped metals. The acid digestion procedures also ...
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Although there are twelve refractory metals, only five are widely used: Tungsten, Molybdenum, Niobium, Tantalum, and Rhenium. …
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As their constituent elements were much more abundant than the refractory elements, the condensation process quite literally snowballed at this point. It is unlikely that more volatile materials such as hydrogen (H 2) or helium (He) ever condensed, even in the cold outer reaches of the nebula. Thus, the low-temperature product of condensation ...
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The most promising directions of the development of heat-resistant alloys (HRAs) based on refractory metals are analyzed. The microstructures characteristic of HRAs, which it is advisable to form in promising alloys, are considered. The stability factors of the microstructure with respect to the diffusion coarsening of the hardening phases are …
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Simultaneously, strengthening elements such as Ti, Co and Mo are added to ameliorate the high-temperature strength. Studies have shown that the addition of refractory elements such as Nb, Hf and Zr has different effects on the oxidation resistance and mechanical properties of Ni-based superalloys [13, 21]. Therefore, combining the …
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Collectively, elemental regulations with Cr and refractory elements are expected to sustain a better oxidation resistance and strengthen the Ni 3 Al-based alloy at elevated temperatures. In addition to the metallic elements, minor addition of B is necessarily requested in the design of IMAs, ...
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The five main elements that belong to this class of metal include the following: Molybdenum (Mo) Rhenium (Re) Niobium (Nb) Tungsten (W) Tantalum (Ta)
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A variety of principal components of MPEA leads to a strong atomic-radius mismatch and modulus mismatch between different elements to provide a good solid-solution-strengthening effect, which has a typical application in the room-temperature and high-temperature strengthening of the refractory high entropy alloy (RHEA) of the BCC …
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The term 'refractory metal' is used to describe a group of metal elements that have exceptionally high melting points and are …
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Overall, the segregation behavior of typical refractory elements was alleviated. As a result, the formation of the eutectic islands in the interdendritic regions was impeded with Mo addition. According to Hobbs et al.'s research [13], the effects of Mo on other alloying elements resulted from the interaction between d-shell electrons. Mo ...
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For example, refractory elements, in a cosmochemical sense, can be siderophile, lithophile, or even chalcophile during planetary differentiation. Care must also be taken when using the terms atmophile and volatile. For example, Pb and Zn are considered highly volatile from a cosmochemical perspective, but would not be considered atmophile.
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Nowadays refractory high-entropy alloys (RHEAs) are regarded as great candidates for the replacement of superalloys at high temperature. To design a RHEA, one must understand the pros and cons of every refractory element. However, the elemental effect on mechanical properties remains unclear. In this study, the subtraction method …
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Tantalum, niobium, molybdenum, and tungsten are the most commonly used refractory metals. 1–4 It is possible to combine these elements, both with other materials and with each other, to create a wide range of high-performance refractory metal compounds and alloys, which are fundamental to several industries.
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Non-refractory elements (Al, Si, or Ni) can also be incorporated into the RHEAs to improve the alloy properties, which further expands the parameter space for alloy design . From the structure perspective, BCC HEAs exhibit a much larger lattice distortion, which could significantly affect their thermodynamic stability and other properties of ...
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But, HEAs (without refractory elements) are more economical than refractory HEAs. This is due to the fact that most of the refractory elements are expensive. The present work focuses on the effect of refractory elements, namely, Mo, W, Ta, Nb, Ti and V on mechanical properties of HEAs. This review also provides an insight …
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Han et al. [] reported that the addition of Ti element in the TiNbMoTaW and TiVNbMoTaW RHEAs was beneficial to the strength and the compressive ductility of the refractory HEAs at room-temperature.The RHEAs possess single BCC phase structure, and could sustain the phase structure even after annealing at 1200 ℃ for 24 h. The room …
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In addition to the metals listed above, we might also consider all metals with a melting point >1,650°Cto be refractory metals: 1. Osmium(Os) 3027°C, HCP 2. Iridium(Ir) 2447°C, FCC 3. Ruthenium(Ru) 2250°C, HCP 4. Hafnium(Hf) 2227°C, HCP 5. Technetium(Tc) 2200°C, HCP (Radioactive) 6. Rhodium(Rh) …
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Atoms exist only in the form of volatile and refractory elements. Consequently, the refractory inorganic material stays unchanged in both models, as stated in Table 3, which summarizes the amount of atoms that form volatile, refractory inorganic, and refractory organic components relative to their total abundance in solar nebula. Hereafter, the ...
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In the refractory HEAs (RHEAs), the GB movement is strongly suppressed even at high temperatures [25], suggesting the good structure stability during irradiation. Note that the RHEAs are natural with high thermal stability, since they are composing of refractory elements.
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Later, a small amount of non-refractory metal elements, such as Al, Si, Co, or Ni, are added to improve its comprehensive properties . Usually, the main functions of specific elements in RHEAs are shown …
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Composed principally of ceramics, refractories are employed in great quantities in the metallurgical, glassmaking, and ceramics industries, where they are formed into a variety …
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The refractory elements (Nb, V, and Zr), Ti and Al with low density are the most commonly used alloying elements to improve the specific yield strength. Ti elements and their alloys possess good ductility and excellent high-temperature properties . For example, the solid-solution hardening effect of Ti addition is beneficial to the compressive ...
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The refractory elements from groups 4, 5 and 6 of the periodic table are key ingredients to many promising high entropy alloys. In this paper we described the results of a comprehensive first-principles study of phase stability of the refractory elements and their 36 binaries. The properties of the elements and their binaries are an important ...
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High-entropy alloys (HEAs) synthesized using refractory elements are being strongly considered as candidates for high temperature structural applications. The role of compositional changes of HEA ...
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Refractory high-entropy alloys (RHEAs) that consist of multiple principal refractory elements have attracted significant attention due to their many interesting and useful properties for structural applications. However, so far, a vast majority of reports on RHEAs focused on a few well-known compositions suc Nanoscale 2022 Emerging …
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The major elements (Mg, Fe, and Si, plus Ni) have lower condensation temperatures than the refractories (Ca, Al) and higher than the moderately volatiles (K and S). Prior studies (Larimer 1979 ; Kerridge 1979 ) have observed that NC chondrites form a distinctive array on the Mg/Si-Al/Si plot as compared to CC meteorites (Fig. 2 ).
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Refractory elements are found predominantly in small silicate ash particles 62,63; or oxide compounds formed by gas-to-particle conversion at high temperatures 18,20,21,67,68,69.
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Refractories emerged with high-temperature technology. Ancient refractories roughly originated in the middle of the Bronze Age (about eighteenth century BC), using simply processed natural refractory materials. ... Functional elements such as ventilation devices promote the development of secondary refining technology. The …
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The refractory elements (including Re, Mo, Ta) and a certain proportion of Ni were first melted to form an intermediate alloy and then remelted with remaining elements. At each step, the alloy buttons were flipped and remelted more than five times. The arc melted alloys were then drop cast into a water chilled copper mold to produce …
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