Static and cyclic oxidation of Nb-Cr-V-W-Ta high entropy alloy in air from 600 to 1400 °C

Fabrication and Characterization of High-Quality Epitaxial Nanocolumnar Niobium Films with Abrupt Interfaces on YSZ(001)

“…Niobium (Nb), a refractory metal, exhibits many mechanical, thermal, thermochemical, and electrical properties useful for a number of modern technological applications. ,− ,, Nb and Nb-based alloys currently dominate several aerospace, defense, electronics, and energy sectors. − Due to its high melting point of 2477 °C, Nb is used in many engineering systems exposed to thermal and mechanical loadings. Nb also exhibits excellent physical and mechanical qualities.…”

“…Nb also exhibits excellent physical and mechanical qualities. Its relatively low density, high Young’s modulus, and high yield strength, which are 8.6 g cm –3 , 103 GPa, and 240–550 N mm –2 , respectively, combined with its electronic properties, make Nb and Nb-based alloys suitable for applications, where materials and devices are often subjected to extreme environments, especially, elevated temperature or pressure or radiation or combination of these. ,− Unlike other refractory metals, Nb finds widespread applications in nanoelectronics and nanophotonics. Nb thin films and nanomaterials are popular for their utilization in nano-SQUID circuits for switches operating at high frequency under cryogenic conditions, superconductivity, single photon detectors, and high-temperature plasmonic applications .…”

Unexpected Superparamagnetic Behavior in Nanocrystalline Niobium-Based High-Entropy Alloys

“…A common strategy that can be noted was mixing and alloying of different metals to exploit their unique characteristics and fabricating new composites with superior functionality and device applicability. − Initially, the strategy was to incorporate a secondary material into the host system and tailor its functionality, such as melting point, hardness, elasticity, corrosion resistance, and so forth. − However, with the scientific advancements made over many years and decades, this approach has become more precise and sophisticated. Scientists and engineers explored many possible ways to design materials, especially the complex alloys, by selectively spanning the search and/or mixing metals available across the periodic table. , In the series of evolution, the most recent attention is toward the high entropy alloys (HEAs) or multiprincipal element alloys (MPEAs), which can fulfil the requirements of future energy, aerospace, and nuclear technologies. − The HEAs/MPEAs were first reported at the dawn of the current century. ,,, On the contrary, with the conventional alloy system, where a small portion of the host material is substituted by secondary elements, the HEA belongs to an equimolar or near equimolar mixture of various elemental metals. , In the entropy contour plot, conventional alloys belong to corners, whereas the HEA overtakes the central region . By definition (composition-based), the HEA should have at least five or more principal elements. − Percentage of each component may vary depending on its characteristic evolution.…”

Zr alloying effects on the microstructure, compression performance and oxidation resistance of refractory high entropy alloys

“…W, Ta, Mo, Nb and Hf with high melting temperatures are important constituent elements of RHEAs, which can provide excellent mechanical properties at room and high temperatures [3]. Nevertheless, the density of W and Ta elements is very high (19.35 and 16.6 g cm −3 respectively), and the former element is unfavorable to the high temperature oxidation resistance of RHEAs due to the formation of volatile tungsten trioxide (WO 3 ) [4,5]. Mo and Nb elements have moderate density (10.2 and 8.57 g cm −3 respectively) and Hf element can ameliorate oxidation resistance of some high melting point alloys by improving the adhesion and compactness of oxide scale, promoting selective oxidation of Ti and other elements and inhibiting inward diffusion of oxygen [6][7][8].…”