A multiscale modelling study of Ni–Cr crack tip initial stage oxidation at different stress intensities

Das, Nishith Kumar; Tirtom, İsmail; Shoji, Tetsuo

doi:10.1016/j.matchemphys.2010.02.068

Cited by 17 publications

(4 citation statements)

References 28 publications

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“…We have applied a hierarchical computational model that consists of three different methods to simulate initial stage of oxidation for SCC problem. The details calculation procedure of FEM, QC, and QCMD methods were given elsewhere [13,14]. The crack tip is a few nanometers wide and chemical reaction is being performed by tight-binding QCMD.…”

Section: Methodsmentioning

confidence: 99%

Stress Intensity Effect on Solid State Oxidation of Ni-Cr Alloy with Different Chromium Concentrates

Tirtom

Das

Shoji

2010

JMMP

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Ni-base alloy is widely used in light water reactor component and the recent study has shown stress corrosion cracking (SCC). Over the years various attempts have been made to obtain mechanism of SCC but it still require more fundamental study to understand clearly. This study presents an approach based on the multiscale modeling, to assess the influence of alloy composition and stress intensity on the initial stage of solid state oxidation of the Ni-Cr alloy. The multiscale modeling considers different length scales such as finite element method (FEM) / quasi-continuum (QC) / quantum chemical molecular dynamics (QCMD), for analyzing crack tip molecular domain. The compact tension (CT) specimen of alloy 600 has been loaded for stress intensity, after that the micro region has chosen for the QC model which is a combination of continuum and atomic method. Finally, the deformed atomic position has picked for the QCMD simulation with some water molecules. The simulated results show that the chromium segregates faster than nickel atoms from the surface and make preferential bonding with oxygen. The preferential bonding forms a passive film. Applied stress intensity deformed the structure which may increase the atomic distance. As distance increases the absorption of water molecule or OH or oxygen into lattice increases. The stress intensity raises the crack tip solid state oxidation that may enhance SCC initiation.

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Section: Methodsmentioning

confidence: 99%

Stress Intensity Effect on Solid State Oxidation of Ni-Cr Alloy with Different Chromium Concentrates

Tirtom

Das

Shoji

2010

JMMP

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“…Reactive prealloy brazing filler metal powder has resolved several technical drawbacks, e.g., the loss of low melting point elements in the brazing filler metal, a difficulty in achieving the high melting point elements playing an assigned role, a volatility of high vapor pressure elements, a structural segregation of components, and ultimately an instability in the bonding strength. However, there are still many problems for the brazing of impregnated diamond tools to be resolved, e.g., a brazing diamond surface can feature cracks [47]. The cracks and/or crushes stem from the high brazing temperature of the Ni-Cr brazing filler metal used in brazing impregnated diamond tools.…”

Section: The Research Status Of Pbfms For Impregnated Diamond Toolsmentioning

confidence: 99%

Research and Development of Powder Brazing Filler Metals for Diamond Tools: A Review

Long

Sekulić

2018

Metals

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Powder brazing filler metals (PBFMs) feature a number of comparative advantages. Among others, these include a low energy consumption, an accurate dosage, a good brazeability, a short production time, and a high production efficiency. These filler metals have been used in the aerospace, automobile, and electric appliances industries. The PBFMs are especially suitable for diamond tools bonding, which involves complex workpiece shapes and requires accurate dosage. The recent research of PBFMs for diamond tools is reviewed in this paper. The current applications are discussed. The CuSnTi and Ni-Cr-based PBFMs have been the two commonly used monolayer PBFMs. Thus, the bonding mechanism at the interface between both the monolayer PBFMs and a diamond tool are summarized first. The ways to improve the performance of the monolayer PBFMs for diamond tools are analyzed. Next, a research of PBFMs for impregnated diamond tools is reviewed. The technical problems that urgently need solutions are discussed. Finally, the challenges and opportunities involved with the PBFMs for diamond tools research and development are summarized, and corresponding prospects are suggested.At present, extensive studies have been conducted on PBFMs. For example, Ivanov et al. [6] studied the solid-phase synthesis of a PBFM for the titanium alloy vacuum brazing. He et al. [7] considered the influence of a powder containing 50% TiH 2 and 50% Ni (used for brazing Ti-Al intermetallic compounds) on the joint structure and mechanical properties. Liu et al. [8] explored the structure and properties of the zirconia and stainless steel joints obtained with Ag-Cu brazing filler metal and TiH 2 PBFM under normal pressure (1.01 × 10 5 Pa). Zhang and Tu [9] investigated the structure and properties of the lead-free solder containing micro/nano powder. Ti-Al intermetallic compounds are extensively applied in the aerospace industry, while the lead-free solder has been widely used in the electronics industry. Ag-Cu brazing filler metal and TiH 2 powder are broadly applied in the ceramics industry. However, the mentioned applications in the aerospace, ceramics, and electronics industries have not been the exclusive application fields of PBFMs.The aforementioned PBFMs cannot necessarily be used in more demanding environments, such as high temperature, high pressure, and heavy loads. The PBFMs for diamond tools occupy a considerable proportion of manufacturing. They has been further implemented in novel application areas, e.g., transportation and mining machineries.In this paper, we review the recent research of PBFMs for diamond tools. The current application status is discussed. The interface bonding mechanism of commonly used monolayer PBFMs for diamond tools is also addressed. Furthermore, the ways to improve the performance of the PBFMs for diamond tools is discussed. The studies of PBFMs for impregnated diamond tools are reviewed. Technical problems that urgently need solutions are discussed. Finally, the limits of applications and prospects of powder brazin...

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“…Despite a large body of previous experimental information about interfacial oxidation processes promoting SCC in Ni-base alloys, detailed microscopic understanding is still lacking. The inherent complexity of the corrosion/oxidation behavior of Ni-base alloys has triggered a number of computational atomistic studies aimed to elucidate the mechanisms and kinetics of electrochemical reactions, adsorption behavior and species diffusion in the bulk and at interfaces [19,[27][28][29][30][31][32][33]. Since many degradation processes occur in aqueous environments, first-principles studies have been devoted to understanding of the interactions between water and Ni surfaces [30,31].…”

Section: Introductionmentioning

confidence: 99%

“…The inherent complexity of the corrosion/oxidation behavior of Ni-base alloys has triggered a number of computational atomistic studies aimed to elucidate the mechanisms and kinetics of electrochemical reactions, adsorption behavior and species diffusion in the bulk and at interfaces [19,[27][28][29][30][31][32][33]. Since many degradation processes occur in aqueous environments, first-principles studies have been devoted to understanding of the interactions between water and Ni surfaces [30,31]. These investigations Density-functional-theory (DFT) calculations were performed using the VASP code [34,35] within the Perdew-Burke-Ernzerhof (PBE) parametrization of the generalized gradient approximation (GGA) [36] combined with the projector augmented wave (PAW) potentials [37].…”

Section: Introductionmentioning

confidence: 99%

Adsorption and diffusion of atomic oxygen and sulfur at pristine and doped Ni surfaces with implications for stress corrosion cracking

et al. 2016

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A density-functional-theory modeling study of atomic oxygen/sulfur adsorption and diffusion at pristine and doped Ni(111) and (110) surfaces is presented. We find that oxygen and sulfur feature comparable adsorption energies over the same surface sites, however, the surface diffusion of sulfur is characterized by an activation barrier about one half that of oxygen. Calculations with different alloying elements at Ni surfaces show that Cr strongly enhances surface binding of both species in comparison to Al. These results in combination with previous modeling studies help explain the observed differences in selective grain boundary oxidation mechanisms of Ni-Cr and Ni-Al alloys.

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A multiscale modelling study of Ni–Cr crack tip initial stage oxidation at different stress intensities

Cited by 17 publications

References 28 publications

Stress Intensity Effect on Solid State Oxidation of Ni-Cr Alloy with Different Chromium Concentrates

Stress Intensity Effect on Solid State Oxidation of Ni-Cr Alloy with Different Chromium Concentrates

Research and Development of Powder Brazing Filler Metals for Diamond Tools: A Review

Adsorption and diffusion of atomic oxygen and sulfur at pristine and doped Ni surfaces with implications for stress corrosion cracking

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