The Study of Microstructural Changes and Effects of Deformation Localization in Copper Alloys at Shock Waves Loading

Flyer plates are used to impose pressure and pulse durations on specimens in explosively loaded systems. It is generally observed that significant changes in microstructure and microhardness are produced by this means. While the e ffect of shock loading on 304 stainless-steel has been investigated and shown to have a ϒ→α transformation, there have been no studies of the flyer plates. The major contribution which effects the flyer plate mirostructure is shock compression (resulting from explosive detonation) and the refracted shock wave after impact with the specimen assembly. The refracted shock waves has been addressed for the specimens. However, this has not been shown experimentally for the flyer plate. We looked at the microstructure of these flyer plates to answer questions raised regarding non-uniform shock fronts resulting from microstructural changes within the flyer-plate due to the shock event.

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A Study on Early Microstructural Changes in the Rabbit Gallbladder Induced by Shock Waves

Journal of the Korean Radiological Society ◽

10.3348/jkrs.1994.30.5.907 ◽

1994 ◽

Vol 30 (5) ◽

pp. 907

Author(s):

Yun Sun Choi ◽

Kun Sang Kim ◽

Hyung Jin Shim ◽

In Sup Song ◽

Eun Oak Oh ◽

...

Keyword(s):

Shock Waves ◽

Microstructural Changes ◽

Rabbit Gallbladder

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Phenomena Associated with Oxygen in Titanium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061562 ◽

1967 ◽

Vol 25 ◽

pp. 310-311

Author(s):

E. U. Lee ◽

P. A. Garner ◽

J. S. Owens

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Electron Microscope ◽

Microstructural Changes ◽

Electrolytic Polishing ◽

Interstitial Impurities ◽

Thin Foils ◽

Transmission Electron ◽

Iodide Titanium ◽

Alpha Titanium

Evidence for ordering (1-6) of interstitial impurities (O and C) has been obtained in b.c.c. metals, such as niobium and tantalum. In this paper we report the atomic and microstructural changes in an oxygenated c.p.h. metal (alpha titanium) as observed by transmission electron microscopy and diffraction.Oxygen was introduced into zone-refined iodide titanium sheets of 0.005 in. thickness in an atmosphere of oxygen and argon at 650°C, homogenized at 800°C and furnace-cooled in argon. Subsequently, thin foils were prepared by electrolytic polishing and examined in a JEM-7 electron microscope, operated at 100 KV.

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Tensile Creep of Y-Si3N4: II. Cavitation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089172 ◽

1991 ◽

Vol 49 ◽

pp. 972-973 ◽

Cited By ~ 1

Author(s):

B. J. Hockey ◽

S. M. Wiederhorn

Keyword(s):

Silicon Nitride ◽

Creep Rupture ◽

Tensile Creep ◽

Sintering Aids ◽

Microstructural Changes

ATEM has been used to characterize three different silicon nitride materials after tensile creep in air at 1200 to 1400° C. In Part I, the microstructures and microstructural changes that occur during testing were described, and consistent with that description the designations and sintering aids for these materials were: W/YAS, a SiC whisker reinforced Si3N4 processed with yttria (6w/o) and alumina (1.5w/o); YAS, Si3N4 processed with yttria (6 w/o) and alumina (1.5w/o); and YS, Si3N4 processed with yttria (4.0 w/o). This paper, Part II, addresses the interfacial cavitation processes that occur in these materials and which are ultimately responsible for creep rupture.

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Investigation of shock-wave deformation history from recovered structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143754 ◽

1986 ◽

Vol 44 ◽

pp. 434-435

Author(s):

M.A. Mogilevsky ◽

L.S. Bushnev

Keyword(s):

Shock Wave ◽

Plastic Deformation ◽

Dislocation Density ◽

Shock Waves ◽

Shock Front ◽

Single Crystals ◽

Residual Deformation ◽

Deformation Structure ◽

Deformation History ◽

Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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Morphology and atomic structure of segregated grain boundaries in Cu-Sb

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121673 ◽

1992 ◽

Vol 50 (1) ◽

pp. 254-255

Author(s):

R. W. Fonda ◽

D. E. Luzzi

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Intergranular Fracture ◽

Atomic Structure ◽

Copper Alloys ◽

Polycrystalline Materials ◽

Grain Boundary Embrittlement ◽

Boundary Embrittlement

The properties of polycrystalline materials are strongly dependant upon the strength of internal boundaries. Segregation of solute to the grain boundaries can adversely affect this strength. In copper alloys, segregation of either bismuth or antimony to the grain boundary will embrittle the alloy by facilitating intergranular fracture. Very small quantities of bismuth in copper have long been known to cause severe grain boundary embrittlement of the alloy. The effect of antimony is much less pronounced and is observed primarily at lower temperatures. Even though moderate amounts of antimony are fully soluble in copper, concentrations down to 0.14% can cause grain boundary embrittlement.

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TEM study of a biofilm on copper corrosion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163563 ◽

1996 ◽

Vol 54 ◽

pp. 220-221

Author(s):

W. A. Chiou ◽

N. Kohyama ◽

B. Little ◽

P. Wagner ◽

M. Meshii

Keyword(s):

Marine Bacterium ◽

Culture Medium ◽

Copper Alloys ◽

Pure Copper ◽

Localized Corrosion ◽

Natural Seawater ◽

Copper Corrosion ◽

New Approach ◽

The Past ◽

Copper Tolerant

The corrosion of copper and copper alloys in a marine environment is of great concern because of their widespread use in heat exchangers and steam condensers in which natural seawater is the coolant. It has become increasingly evident that microorganisms play an important role in the corrosion of a number of metals and alloys under a variety of environments. For the past 15 years the use of SEM has proven to be useful in studying biofilms and spatial relationships between bacteria and localized corrosion of metals. Little information, however, has been obtained using TEM capitalizing on its higher spacial resolution and the transmission observation of interfaces. The research presented herein is the first step of this new approach in studying the corrosion with biological influence in pure copper.Commercially produced copper (Cu, 99%) foils of approximately 120 μm thick exposed to a copper-tolerant marine bacterium, Oceanospirillum, and an abiotic culture medium were subsampled (1 cm × 1 cm) for this study along with unexposed control samples.

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