Carbon, Nitrogen and Hydrogen in Iron-Based Solid Solutions: Similarities and Differences in their Effect on Structure and Properties

Gavriljuk, V.G.

doi:10.15407/mfint.38.01.0067

Cited by 7 publications

(2 citation statements)

References 66 publications

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“…The both elements increase the density of electron states at the Fermi level 59 and, correspondingly, increase the concentration of free electrons, 60,61 cause the γ ε → transformation 62 and affect iron properties in a similar way. 63,64 Like hydrogen, nitrogen is a volatile element, and the both are negligibly dissolved in the iron. Like the Fe-H phase diagram, the Fe-N one is constituted not for p N2 = 1 bar, but for very high partial pressures of nitrogen provided by the dissociation of ammonia.…”

Section: Metal Hydrides and Thermodynamicsmentioning

confidence: 99%

Electron structure and thermodynamics of solid solutions in Ni–H system

VG¹

2018

MSEIJ

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The widespread concept of nickel hydride in the Ni–H system is discussed based on the first–principle atomic calculations and experimental X–ray diffraction data. The total cohesion energy in Ni–H solid solution has been determined using the density functional theory and program package Wien2k. Its dependence on hydrogen concentration is shown to be linear, which suggests the absence of any energy barrier for precipitation reaction. Moreover, the second derivative of the calculated solution enthalpy is negative within the hydrogen–to–nickel ratios, H/Ni, of 0.03 to 0.75, which is a sign of spinodal decomposition. These hydrogen concentrations are consistent with the measurements of X–ray diffraction, of which results are traditionally interpreted in terms of Ni hydride. The density of electron states has been calculated, and its non–monotonous concentration dependence correlates with that of solution enthalpy, which is also expected for spinodal decomposition. The obtained results are interpreted as miscibility gap in the Ni–H system with spinodal decomposition having the electron origin. In addition, using mechanical spectroscopy, the strain dependent internal friction has been observed in the hydrogen–charged nickel with H/Ni ratio of about 0.7. This effect is controlled by irreversible plastic deformation, which is typical for solid solutions, not for brittle chemical compounds. Finally, the “hydrides” in a number of metals are discussed in terms of two Gibb’s types of precipitation reactions. Keywords: nickel, hydrogen, ab initio calculations, spinodal decomposition, hydride

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Section: Metal Hydrides and Thermodynamicsmentioning

confidence: 99%

Electron structure and thermodynamics of solid solutions in Ni–H system

VG¹

2018

MSEIJ

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“…Jiang et al [2] studied the diffusion mechanism of H and used DFT to understand between octahedral and tetrahedral interstitial sites in Fe regarding which site is more likely to be occupied by H. Moreover, DFT has been used to develop interatomic potentials to simulate Fe-H systems by Ramasubramaniam et al [7]. Gavriljuk et al [8] experimentally and theoretically investigated the effect of C, N, and H on electrical, mechanical, and material characteristics of Fe-based solid solutions. There is a gap in the literature regarding the effect of hydrogen on the physical properties of iron-based solid solutions using DFT calculations.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrogen on the electrical resistivity of Fe and Fe-C systems : a first principles study

Ahmad,

Singh,

Eybel

et al. 2023

Progress in Canadian Mechanical Engineering. Volume 6

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Hydrogen Embrittlement (HE) in steel is an important phenomenon that needs to be understood from several perspectives. HE promotes crack growth and lower ductility hence it poses a risk of failure in the material. An important aspect that needs further research in the domain of HE is the effect of hydrogen (H) on the physical properties of steel. A better understanding of this aspect could contribute to the development of a non-destructive testing technique for detecting the change in physical properties in the presence of H in the material. This study investigates the effect of Hconcentration on the electrical resistivity of iron (Fe) and ironcarbon (Fe-C) systems using density functional theory (DFT). An increase in resistivity with the increase in H-concentration was observed in both Fe and Fe-C systems. The addition of H and C to the Fe system is found to negligibly affect the density of states (DOS) at the fermi level which is proportional to the number of free electrons in the system. Whereas the addition majorly affects the probability of an incident electron wave being transmitted through the system in its transport direction by scattering it.

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