Open AccessCreep rupture properties of bare and coated polycrystalline nickel-based superalloy Rene®80
Author(s) -
Mohammad Mehdi Barjesteh,
S.M. Abbasi,
K. Zangeneh-Madar,
Kourosh Shirvani
Publication year - 2021
Publication title -
journal of mining and metallurgy. section b, metallurgy/journal of mining and metallurgy. section b, metallurgy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.42
H-Index - 20
eISSN - 2217-7175
pISSN - 1450-5339
DOI - 10.2298/jmmb201203036b
Subject(s) - vanadium , creep , superalloy , nickel , crystallite , materials science , metal , oxygen , metallurgy , chemical engineering , chemistry , microstructure , organic chemistry , engineering
The mechanism governing de-oxidation of vanadium metal is regarded as fundamental knowledge; however, it has not been elucidated in existing literature. In this paper, the thermodynamic data of V-H-O systems were summarized, and the Gibbs free energies of the main compounds were calculated. Consequently, the de-oxidation limits of different reductants in a VO system were evaluated, namely: Si, Al, and Mg. It was observed that Si could not remove an O content of less than 7.27 wt% from V. However, Al was the stronger reducing agent; it could remove O contents of up to 0.01 and 0.1 wt% at 800 and 1050?C, respectively. Nevertheless, Mg exhibited the best reducing properties as it could remove less than 0.01 wt% of O at 1100?C. The addition of H2 rendered the V-O solid solution unstable to a certain extent, thereby indicating that H2 facilitated de-oxygenation. Furthermore, the results obtained by analyzing the equilibrium conditions were in accordance with the results of the de-oxidation limit in the V-O system. In other words, this study demonstrated that oxygen in vanadium can be effectively controlled by changing the reductant dosage and temperature.