Effect of oxygen on vacancy cluster morphology in metals

Zinkle, S.J.; Lee, E. H.

doi:10.1007/bf02656525

Cited by 12 publications

(3 citation statements)

References 110 publications

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“…Irradiation studies (that introduce large concentrations of vacancies) of metals at large temperatures have shown that oxygen stabilizes void nucleation compared to the other vacancy cluster defects, by decreasing the void surface energy through a chemisorption process. [44][45][46][47][48] We therefore expect a similar scenario during the fatigue damage of the Ni microbeams. In air, the formation of voids is facilitated by the presence of oxygen (which is consistent with our observation of large oxygen concentrations at the location of the voids), resulting in faster crack growth rates.…”

mentioning

confidence: 79%

Quantitative in Situ SEM High Cycle Fatigue: The Critical Role of Oxygen on Nanoscale-Void-Controlled Nucleation and Propagation of Small Cracks in Ni Microbeams

2018

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This Letter presents a quantitative in situ scanning electron microscope (SEM) nanoscale high and very high cycle fatigue (HCF/VHCF) investigation of Ni microbeams under bending, using a MEMS microresonator as an integrated testing machine. The novel technique highlights ultraslow fatigue crack growth (average values down to ∼10 m/cycle) that has heretofore not been reported and that indicates a discontinuous process; it also reveals strong environmental effects on fatigue lives that are 3 orders of magnitude longer in a vacuum than in air. This ultraslow fatigue regime does not follow the well documented fatigue mechanisms that rely on the common crack tip stress intensification, mediated by dislocation emission and associated with much larger crack growth rates. Instead, our study reveals fatigue nucleation and propagation mechanisms that mainly result from room temperature void formation based on vacancy condensation processes that are strongly affected by oxygen. This study therefore shows significant size effects governing the bending high/very high cycle fatigue behavior of metals at the micro- and nanoscales, whereby the stress concentration effect at the tip of a growing small fatigue crack is assumed to be greatly reduced by the effect of the bending-induced extreme stress gradients, which prevents any significant cyclic crack tip opening displacement. In this scenario, ultraslow processes relying on vacancy formation at the subsurface or in the vicinity of a crack tip and subsequent condensation into voids become the dominant fatigue mechanisms.

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confidence: 79%

Quantitative in Situ SEM High Cycle Fatigue: The Critical Role of Oxygen on Nanoscale-Void-Controlled Nucleation and Propagation of Small Cracks in Ni Microbeams

2018

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“…A number of neutron, ion, and electron irradiation studies have shown that voids are not formed in high-purity, low-oxygen copper over the wide range of irradiation temperatures. 60,86 The oxygen content should be maintained below $10 wt ppm to minimize void swelling in copper.…”

Section: Irradiation Creep and Void Swellingmentioning

confidence: 99%

Physical and Mechanical Properties of Copper and Copper Alloys

Li¹,

Zinkle²

2012

Comprehensive Nuclear Materials

165

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“…[42][43][44][45][46][47][48] In our experiment, due to the very low concentration of He, the formed cavities are most likely void. [42][43][44][45][46][47][48] Our estimation show that even for an average He concentration of 0.08 at.%, the ratio of vacancy to He in a 5 nm cavities is larger than 33 in irradiated Cu. Therefore, the TEM observations will show voids due to the agglomeration of irradiation-induced vacancies and not pressurized He bubbles.…”

Section: A He Concentration and Damage Profilementioning

confidence: 99%

Irradiation damage of single crystal, coarse-grained, and nanograined copper under helium bombardment at 450 °C

Han

Demkowicz

et al. 2013

J. Mater. Res.

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The irradiation damage behaviors of single crystal (SC), coarse-grained (CG), and nanograined (NG) copper (Cu) films were investigated under Helium (He) ion implantation at 450°C with different ion fluences. In irradiated SC films, plenty of cavities are nucleated, and some of them preferentially formed on growth defects or dislocation lines. In the irradiated CG Cu, cavities formed both in grain interior and along grain boundaries; obvious void-denuded zones can be identified near grain boundaries. In contrast, irradiation-induced cavities in NG Cu were observed mainly gathering along grain boundaries with much less cavities in the grain interiors. The grains in irradiated NG Cu are significantly coarsened. The number density and average radius of cavities in NG Cu was smaller than that in irradiated SC Cu and CG Cu. These experiments indicate that grain boundaries are efficient sinks for irradiation-induced vacancies and highlight the important role of reducing grain size in suppressing radiation-induced void swelling.

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Effect of oxygen on vacancy cluster morphology in metals

Cited by 12 publications

References 110 publications

Quantitative in Situ SEM High Cycle Fatigue: The Critical Role of Oxygen on Nanoscale-Void-Controlled Nucleation and Propagation of Small Cracks in Ni Microbeams

Quantitative in Situ SEM High Cycle Fatigue: The Critical Role of Oxygen on Nanoscale-Void-Controlled Nucleation and Propagation of Small Cracks in Ni Microbeams

Physical and Mechanical Properties of Copper and Copper Alloys

Irradiation damage of single crystal, coarse-grained, and nanograined copper under helium bombardment at 450 °C

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