Neutron Irradiated Copper Research Articles

High-precision measurements of lattice parameter changes in neutron-irradiated copper

The dose dependence of the lattice parameter change for neutron-irradiated copper has been measured in the range (1.0–10.8)×1018 neutrons/cm2. The lattice parameter changes were measured directly by using a multiply reflecting monochromator, and an analysis of the effects of misalignment in the geometry has been given. The lattice parameter changes, showing a pronounced saturation with dose, were analyzed using second-order elasticity theory applied to the case of dislocation loops.

Deformation of neutron irradiated copper alloys

Deformation of neutron irradiated copper alloys

Study of slip band development on neutron-irradiated copper single crystals by high speed cinematography

Study of slip band development on neutron-irradiated copper single crystals by high speed cinematography

Effect of primary recrystallization on the recovery stage-V of neutron irradiated copper

Abstract In these experiments we have measured the recovery spectra of the electrical resistivity after neutron irradiation at 78 °K of previously cold-worked copper specimens at room temperature and compared with well annealed specimens after neutron irradiation.

The effect of impurity atoms on the recovery of neutron irradiated copper at 78 °K

physica status solidi (a)Volume 12, Issue 1 p. K59-K63 Short Note The effect of impurity atoms on the recovery of neutron irradiated copper at 78 °K K. Papathanassopoulos, K. Papathanassopoulos Nuclear Research Center “Democritus”, Aghia Paraskevi, Attikis, AthensSearch for more papers by this authorP. Andronikos, P. Andronikos Nuclear Research Center “Democritus”, Aghia Paraskevi, Attikis, AthensSearch for more papers by this author K. Papathanassopoulos, K. Papathanassopoulos Nuclear Research Center “Democritus”, Aghia Paraskevi, Attikis, AthensSearch for more papers by this authorP. Andronikos, P. Andronikos Nuclear Research Center “Democritus”, Aghia Paraskevi, Attikis, AthensSearch for more papers by this author First published: 16 July 1972 https://doi.org/10.1002/pssa.2210120152Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume12, Issue116 July 1972Pages K59-K63 RelatedInformation

Correlation between cleared channels and surface slip steps in neutron irradiated copper crystals

Abstract A technique utilizing electroplating is described for the preparation of specimens for transmission electron microscopy, which show the relation between surface detail and internal structure. The cleared channels in deformed neutron irradiated copper crystals have been correlated with surface slip steps indicating that the surface slip bands are a true representation of the bulk deformation behaviour. The slip steps show a uniform distribution of shear within the central region of the cleared channel, with a decreasing shear strain near the edges. The channel is, however, cleared of irradiation produced defects for approximately the full width of the slip step, indicating that the removal mechanism is relatively efficient. This and other features of the slip process are discussed in terms of the observations.

The Effects of Pre-irradiation Treatments on the Chemical Behavior of 64Cu Recoil Atoms in Neutronirradiated Copper Phthalocyanine

Abstract The chemical behavior of 64Cu recoil atoms was studied in copper phthalocyanine which had been quenched from an elevated temperature or exposed to 60Co γ-rays before the neutron irradiation. In the quenched β-crystal, the initial retention was found to increase with an increase in the temperature of pre-irradiation heating, while the plateau retention of the post-neutron annealing reaction decreased. These results were compared with those for cadmium phthalocyanine and were understood in terms of “dislocation” in the crystal, the recoil atoms being assumed to be trapped and stabilized in the “dislocation.” Although the variations were small, the irradiation with 60Co γ-rays caused a change in the chemical behavior of the recoil atom. The role of some radiation-induced species were discussed.

Irradiation creep associated with dislocation climb

Abstract It is believed that creep in materials containing a dispersed second phase may be controlled by the climb of edge dislocations around the second phase. The above model is proposed to be applicable to neutron irradiated materials containing Seeger zones. It is assumed that edge dislocations are pinned by the zones and can escape by (1) climbing out of the zones by absorption of neutron produced point defects, (2) the dissolution of the zones by absorption of neutron produced interstitials, (3) the dissolution of the zones by vacancy emission from the zones and (4) thermally activated cutting of the zones by the dislocations. The above four mechanisms are incorporated into a set of equations similar to those originally proposed by Seeger for hardening in neutron irradiated copper. The effects of temperature, neutron flux, fluence, and applied stress are considered.

Anomalous-X-Ray-Transmission Investigation of Neutron-Irradiated Copper: Comparison of Theory and Experiment

Anomalous-X-Ray-Transmission Investigation of Neutron-Irradiated Copper: Comparison of Theory and Experiment

Recovery of Lattice Parameter and Electrical Resistivity in Low-Temperature Neutron-Irradiated Copper

The fast---neutron-irradiation-induced change and subsequent isochronal annealing recovery of the lattice parameter and electrical resistivity of copper were studied. A wire resistivity specimen and single crystal were irradiated together in liquid helium and transferred to a cryostat without warm up. The simultaneous recovery of both properties was measured at 4.2\ifmmode^\circ\else\textdegree\fi{}K following isochronal anneals to temperatures as high as 675\ifmmode^\circ\else\textdegree\fi{}K. The results of the three successful experimental runs were in good agreement. An analysis, based on linear superposition of the effects of the individual defects, is presented as the simplest and most direct approach to determine the migration mechanism as a function of temperature. The most significant and unambiguous conclusion of this analysis is that stage-III recovery in copper (220-280 \ifmmode^\circ\else\textdegree\fi{}K) is due to vacancy migration. Alternative explanations in terms of more complex phenomena appear less probable, but cannot be excluded with certainty.

The Effect of Chromatic Aberration on the Visibility of Defect Clusters in Irradiated Metals

In recent years considerable attention has been directed to the interrelation of chromatic aberration and energy loss on the resolution of electron microscopes; however, the related problem of the effect of chromatic aberration and energy loss on the visibility of defect structures appears to have not been considered and is the subject of this paper.Electron microscope studies of the defect clusters present in fast neutron irradiated copper and heavy ion irradiated gold have shown that the apparent cluster size distributions are affected by changes in the specimen thickness, accelerating voltage, objective focal length and aperture size in a manner that indicates that chromatic aberration in conjunction with the energy spread due to energy loss of the image forming electrons is responsible for the differences noted. Figure 1 shows cluster size distributions for fast neutron irradiated copper and heavy ion irradiated gold in which it is clear that the apparent densities of cluster sizes less than about 50 Å in diameter are affected by the experimental parameters noted above. The qualitative effect of the experimental parameters on the apparent densities of the smaller defect clusters follows closely the behavior expected from calculations of the radius of the disc of confusion using the equations shown in Fig. 1 and tabulated in the tables. The curves in Fig. 1 indicate that there is no sharp cutoff in the cluster density, and accordingly, it is not clear what criteria should be employed in relating the experimental parameters to the experimental results.

On the energy of radiation defect clusters in neutron-irradiated copper

physica status solidi (a)Volume 2, Issue 4 p. K263-K267 Short Note On the energy of radiation defect clusters in neutron-irradiated copper K. S. Pedchenko, K. S. Pedchenko Institute of Physics of the Ukrainian Academy of Sciences, KievSearch for more papers by this authorV. S. Karasev, V. S. Karasev Institute of Physics of the Ukrainian Academy of Sciences, KievSearch for more papers by this author K. S. Pedchenko, K. S. Pedchenko Institute of Physics of the Ukrainian Academy of Sciences, KievSearch for more papers by this authorV. S. Karasev, V. S. Karasev Institute of Physics of the Ukrainian Academy of Sciences, KievSearch for more papers by this author First published: 16 August 1970 https://doi.org/10.1002/pssa.19700020441AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume2, Issue416 August 1970Pages K263-K267 RelatedInformation

Density and size distribution of defect clusters in neutron-irradiated copper

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The effect of elastic anistropy on the electron microscope images of small defect clusters in neutron irradiated copper and gold

Abstract The theory of Yoffe (1970) is compared with experiment. Her theory predicts the direction of streaking of electron microscope images of Frank loops in copper and gold quite well; better than older theories based on isotropic elasticity.

Deviations from Matthiessen's rule and longitudinal magnetoresistance in cold-worked and neutron-irradiated copper

Deviations from Matthiessen's rule (MR) in cold-worked Cu samples have been measured as a function of temperature between 4°K and room temperature. They can amount up to 100% of the residual resistivity. A second group of measurements concerns deviation from the additivity of the residual resistivities that arise in the deformed specimens when point defects are added at 4.6° K during a neutron irradiation. In a third group of experiments we investigated deviations from MR as a function of temperature in undeformed Cu samples that have been neutron irradiated at 4.6°K and annealed at different temperatures. There are two essential reasons for these deviations: (1) Defects can change the vibrational behavior of the lattice and so alter the temperature-dependent part of the electrical resistivity. The additional resistivity is found experimentally and theoretically to depend asT 5 on temperature at low temperatures. (2) Anisotropies in the Fermi surface of Cu and in the scattering potentials of the defects give rise to deviations from MR. These deviations can be described by a two-band model for the conduction electrons. Within the framework of this model we were able to describe the deviations that were measured in the deformed Cu samples and in Cu alloys (earlier experiments) in a consistent way, using the same parameters (ratio τ N /τ B of the relaxation times for the neck and belly of the Fermi surface) for the two-band model. Furthermore we could show that the enhanced resistivity increase during neutron irradiation observed in deformed Cu samples is not the consequence of an enhanced defect production rate but that it is a result of deviations from MR due to the different scattering behavior of the defects induced by irradiation and cold work. Measurements of the longitudinal magnetoresistance of the deformed and irradiated copper samples give additional information about the scattering anisotropy of the defects and therefore allow for separating the contributions of the two types of defects the combination of which causes deviations from MR.

Boundary migration in neutron-irradiated copper bicrystals

Boundary migration in neutron-irradiated copper bicrystals

A model for channel behaviour during cyclic deformation of neutron irradiated copper

Cyclic strain experiments have been conducted to determine the widening behaviour of cleared channels in neutron irradiated copper as a function of applied reverse strain per cycle. It is found that widening occurs during only a portion of each cycle. A model is developed which explains this and other experimental observations in terms of the effect of stress fields surrounding clusters of dislocation dipoles which are found in the channels.

Recovery of Fast Neutron Irradiated Copper and Gold at Low-Temperatures

The recovery of the electrical resistivity of 99.999% purity Cu and Au and Au-0.1% Cu alloy was studied after fast neutron irradiation at liquid He temperature. The damage production rate decreased by cold work and alloying in Au, but it increased by cold work in Cu. Cold work enhanced the recovery above 150°K in Cu and above 50°K in Au. In Au, the stage III recovery shifted by about 30°K toward lower temperature for cold worked specimens.

The spatial distribution of irradiation damage spots

The fine-scale damage spots observed in thin foils of neutron irradiated copper do not always appear to be entirely randomly distributed, showing in particular some apparent lining up of spots. A digital computer has been used to determine the number of linear triplets of spots in both a foil and a series of random arrays, the results being displayed pictorially by an electronic graph plotter. No significant difference between the results for the foil and the random arrays was found. The near randomness of the spots was confirmed by counts of the density distribution function for two foils, which both showed almost a Poisson distribution. It is concluded that the apparent “structure” in the distribution of the irradiation damage spots is wholely compatible with that of random arrays. This result may have general implications in other branches of metallography.

The obstacles responsible for the hardening of neutron irradiated copper crystals

Abstract A critical analysis has been made of both the experimental evidence on the deformation characteristics of neutron irradiated copper crystals and the hardening models which have been proposed. It is shown that the observed behaviour is explicable only in terms of the presence in as-irradiated crystals of a spectrum of thermally activated obstacles with values of F max of μb 2 and greater. During annealing the obstacles with the smallest values of F max are removed first, resulting in the formation of a low temperature ‘athermal’region in the flow stress–temperature curve with deformation characteristics similar to those observed in crystals containing very hard second-phase particles. The conclusion of Koppenaal and Arsenault (1965) that only a single type of thermally activated obstacle exists in irradiated copper is shown to be incorrect. Fleischer's (1962 b) theory, as applied to irradiation hardening, is criticized.