Tungsten

About: Tungsten is a research topic. Over the lifetime, 35225 publications have been published within this topic receiving 456213 citations. The topic is also known as: W & element 74.

Effect of aging treatments on microstructure and impact properties of tungsten substituted 2205 duplex stainless steel

Abstract: The effects of partial substitution of tungsten for molybdenum on the microstructure and impact properties in 22Cr–5Ni–3Mo (wt-%) duplex stainless steel (DSS) have been investigated following aging heat treatments in the temperature range 600–1000°C. During aging the intermetallic σ and χ phases were precipitated, and the impact toughness was significantly decreased with an increase in the σ phase content. The χ phase had been precipitated on the α/γ boundary in the early stages of aging. Ferrite and χ phases in tungsten substituted duplex stainless steel contain a large amount of tungsten, and their decomposition rates are much lower compared with those in steel containing only molybdenum. Consequently, the precipitation of the σ phase is retarded in tungsten substituted DSSs, which results in high impact toughness. However, after aging for a long time, the α and χ phases transformed to the σ and austenite phases in the tungsten substituted steels, and the steels showed low impact toughness.

Oxide halides of molybdenum and tungsten. I. Preparations

Abstract: New preparations of molybdenum oxide tetrachloride, MoOCl4; tungsten oxide tetrachloride, WOCl4; molybdenum oxide trichloride, MoOCl3; molybdenum dioxide dibromide, MoO2Br2; and molybdenum oxide tribromide, MoOBr3, have been developed. It has been shown that all previous preparations of molybdenum pentachloride apparently contained some oxide tetrachloride. The magnetic susceptibility of pure molybdenum pentachloride has been measured over a temperature range.

WSe2-contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

Abstract: Contact metals (Au, Ir, and Cr) are deposited on bulk WSe2 under ultra-high vacuum (UHV, 1 × 10−9 mbar) and high vacuum (HV, 5 × 10−6 mbar) conditions and subsequently characterized with x-ray photoelectron spectroscopy (XPS) to elucidate the effects of reactor base pressure on resulting interface chemistry, contact chemistry, and band alignment. Au forms a van der Waals interface with WSe2 regardless of deposition chamber ambient. In contrast, Ir and Cr form a covalent interface by reducing WSe2 to form interfacial metal selenides. When Cr is deposited under HV conditions, significant oxygen incorporation is observed resulting in the thermodynamically favorable formation of tungsten oxyselenide and a substantial concentration of Cr x O y . Regardless of contact metal, WO x (2.63 < x < 2.92) forms during deposition under HV conditions which may positively affect interface transport properties. Cr and Ir form unexpectedly large electron and hole Schottky barriers, respectively, when deposited under UHV conditions due to interfacial reactions that contribute to anomalous band alignment. These results reveal the true interface chemistry formed between metals and WSe2 under UHV and HV conditions and demonstrate the impact on the Fermi level position following contact formation on WSe2.