Deformation of Ag/1.2 at.% Mg

Goretta, K. C.; Routbort, J.L.; Thayer, R.; Carroll, J.P.; Wolfenstine, J.; Kessler, J.; Schwartz, J.

doi:10.1016/0921-4534(96)00298-5

Cited by 20 publications

(16 citation statements)

References 26 publications

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“…The oxidation front penetrated =140~m into the specimen, In this oxygenated region, the Knoop hardness was =160 MPa. Immediately ahead of the oxidation fi-ont, the hardness dropped abruptly to =40 MPa, which agrees weil with the annealed hardness of pure Ag [23]. The hardness of the oxidized region is as much as four to"five times higher.…”

Section: A Kinetics and Microstructural Featuressupporting

confidence: 72%

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Internally oxidized Ag/1.2 at.% Mg sheaths for Bi-2223 tapes

Prorok

Park

Goretta

et al. 2001

IEEE Trans. Appl. Supercond.

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For high-power operation of charged particle rf accelerators, the input coupler windows must withstand enormous stresses due to charging induced by the highenergy charged particle beam passing by and high rf power passing through. Simx most couplers use a single coupling aperture, harmfid asymmetrical rf kick on the beam at the coupler-cavity interface exists. If this problem is solved by dual cxmpIing, the size of the structure becomes a problem. The almve problems are considered common to both normal conducting and superconducting rf accelerators. In superconducting structures, since the frequency of operation is usually around 1 GHz, compactness of the coupler is also a great concern for the cryostat design. Two new waveguide coupler designs that may solve the above-mentioned problems are discussed.

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Section: A Kinetics and Microstructural Featuressupporting

confidence: 72%

“…The hardness of the oxidized region is as much as four to"five times higher. The presence of O caused an increase in lattice strain, from both ffee interstitial O and O associated with the Mg solute; the result was significant obstruction cf dislocation motion [22], [23].…”

Section: A Kinetics and Microstructural Featuresmentioning

confidence: 99%

Internally oxidized Ag/1.2 at.% Mg sheaths for Bi-2223 tapes

Prorok

Park

Goretta

et al. 2001

IEEE Trans. Appl. Supercond.

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“…The fewer, smaller and perhaps pure O 2 bubbles formed in the melt allowed the critical current I c (4.2 K, 5 T) to be doubled. CIPping needs a pressure at least 65 MPa to achieve higher packing density, since the yield strength of pure silver is about 65 MPa [27], [28]. Silver alloy sheath is normally used for Bi-2212 conductors for better strength, so that pressure much higher than 65 MPa is needed for CIPping.…”

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confidence: 99%

Reduction of Gas Bubbles and Improved Critical Current Density in Bi-2212 Round Wire by Swaging

Jiang

Miao²,

Huang³

et al. 2013

IEEE Trans. Appl. Supercond.

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Bi-2212 round wire is made by the powder-in-tube technique. An unavoidable property of powder-in-tube conductors is that there is about 30% void space in the as-drawn wire. We have recently shown that the gas present in the as-drawn Bi-2212 wire agglomerates into large bubbles and that they are presently the most deleterious current limiting mechanism. By densifying short 2212 wires before reaction through cold isostatic pressing (CIPping), the void space was almost removed and the gas bubble density was reduced significantly, resulting in a doubled engineering critical current density (J E ) of 810 A/mm 2 at 5 T, 4.2 K. Here we report on densifying Bi-2212 wire by swaging, which increased J E (4.2 K, 5 T) from 486 A/mm 2 for asdrawn wire to 808 A/mm 2 for swaged wire. This result further confirms that enhancing the filament packing density is of great importance for making major J E improvement in this roundwire magnet conductor. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Abstract-Bi-2212 round wire is made by the powder-in-tube technique. An unavoidable property of powder-in-tube conductors is that there is about 30% void space in the as-drawn wire. We have recently shown that the gas present in the asdrawn Bi-2212 wire agglomerates into large bubbles and that they are presently the most deleterious current limiting mechanism. By densifying short 2212 wires before reaction through cold isostatic pressing (CIPping), the void space was almost removed and the gas bubble density was reduced significantly, resulting in a doubled engineering critical current density (J E ) of 810 A/mm 2 at 5 T, 4.2 K. Here we report on densifying Bi-2212 wire by swaging, which increased J E (4.2 K, 5 T) from 486 A/mm 2 for as-drawn wire to 808 A/mm 2 for swaged wire. This result further confirms that enhancing the filament packing density is of great importance for making major J E improvement in this round-wire magnet conductor.

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“…When oxidation occurs in the Ag(Mg) sample, the measured strain can include both an elastic part due to elastic stress but, also, a chemical strain because of a modification of the stress-free lattice spacing during oxidation of the Mg solute. At such a temperature, Goretta et al 19 measured a yield stress of Ag-1.2 at.% Mg of 383 MPa after oxidation at 900°C for 4 hr. Assuming a biaxial state of stress r in the sample, a Young's modulus E of 83 GPa and a Poisson ratio m of 0.37; the out of plane strain e ?…”

Section: Methodsmentioning

confidence: 98%

First Stages of Internal Oxidation in Ag-0.29 and 2.89 at. % Mg Single-Crystal Alloys

et al. 2006

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Internal oxidation of Ag-0.29 and 2.89 at.% Mg alloys was studied by in-situ X-ray measurements at 300°C. The kinetics and lattice-parameter changes as a function of time are discussed in terms of the formation of elementary MgO* species and non-stoichiometric clusters, during the first stages of oxidation. Studies were made using synchrotron radiation on single-crystal samples. The distorted zone, formed near the surface, was detected by measuring the position and the intensity of the (022) silver peak in the solid-solution alloy. From the diffraction-peak changes, information is deduced on the growth kinetics of the expanded layer. Oxygen diffusivity in silver, C 0 D 0 , is calculated on the basis of Wagner's law. At an early stage, the oxygen diffusivity is slightly lower than the theoretical value. During a second stage, accelerated kinetics give a very high C 0 D 0 value. We determined the O/Mg ratios at different stages during oxidation.

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Deformation of Ag/1.2 at.% Mg

Cited by 20 publications

References 26 publications

Internally oxidized Ag/1.2 at.% Mg sheaths for Bi-2223 tapes

Internally oxidized Ag/1.2 at.% Mg sheaths for Bi-2223 tapes

Reduction of Gas Bubbles and Improved Critical Current Density in Bi-2212 Round Wire by Swaging

First Stages of Internal Oxidation in Ag-0.29 and 2.89 at. % Mg Single-Crystal Alloys

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