bluuebunny/crossref_metadata_2025 huggingface dataset:
Interlaboratory Comparison of the ASTM Bioconcentration Test Method Using the Eastern Oyster
Authors: Schimmel SC , Garnas RL
Published: December 2008

This paper summarizes the results of an interlaboratory comparison conducted by four laboratories for bioconcentration factor (BCF) testing using the eastern oyster (Crassostrea virginica) and the organic chemicals pentachlorophenol (PCP), 1,2,4-trichlorobenzene (TCB), and p, p′-DDE. The bioconcentration test method used was Draft 9 of ASTM Proposed Standard Practice for Conducting Bioconcentration Tests with Fishes and Saltwater Bivalve Molluscs. The mean steady state BCFs and high to low BCF ratios (H/L ratio) for PCP, TCB, and p,p′-DDE were 64 (2.4), 168 (2.3), and 52 600 (3.4), respectively. The mean high to low ratio for all three chemicals was 2.7, which represents the extreme estimate of variability. The mean H/L ratios for the time to 90% uptake were 6.2 for PCP and 5.8 for TCB while the ratio for time to 90% depuration for all three chemicals was 3.3. The results were reproducible, considering the varying degrees of experience between participants in conducting BCF tests, the wide geographic distribution between participants, and the different dilution water characteristics.
Harmonization of Biological Testing Methodology: A Performance-Based Approach
Authors: Williams LR
Published: December 2008

The latitude provided in many written biological test methods, including ASTM standard practices, is such that different laboratories can produce widely varying test results on the same test materials while in technical compliance with the “method.” One obvious solution to this problem is to standardize upon more tightly controlled, less flexible testing procedures. This approach, while widely accepted in the field of chemistry, has been strongly resisted by the biological testing community. This paper presents an alternative approach to achieving comparability of testing data among laboratories while retaining a high degree of flexibility for the individual laboratory. The keys to this approach are (1) the development and routine use of standard reference materials for test system calibration and control, (2) the development of “reference standard methods” that are sufficiently controlled that responses of the test systems to known test materials are predictable and reproducible, and (3) participation in external performance evaluation programs. Recommendations for implementation of a performance-based method evaluation program are offered.
The Effects of an Acidic River, Caused by Acidic Rain, on Weight Gain, Steroidogenesis, and Reproduction in the Atlantic Salmon (Salmo salar)
Authors: Freeman HC , Sangalang GB
Published: December 2008

In 1981, wild male Atlantic salmon (Salmo salar) captured in the low pH (pH 4.7) Westfield River, Nova Scotia, Canada, had lower plasma androgen levels at sexual maturity compared to levels in wild male salmon sampled in the nearby less acidic (pH 5.6) Medway River. In 1982, Atlantic salmon held in cages and fed daily in the Westfield River (pH range 5.1 to 5.3) during the last three months of their sexual maturation cycle gained less weight, produced smaller eggs, and had abnormal steroid hormone metabolism compared to similar fish held in the less acidic Medway River (pH range 5.4 to 6.1). The mortality of eggs taken and fertilized from salmon held in the Westfield River exceeded 90% while the mortality of eggs from the Medway River salmon was 59%.
Usefulness of the Lipid Index for Bioaccumulation Studies with Daphnia magna
Authors: Dauble DD , Klopfer DC , Carlile DW , William Hanf R
Published: December 2008

Bioaccumulation studies with Daphnia magna have become an important tool for hazard evaluation of potentially toxic materials released to aquatic environments. Despite widespread use of this test organism, little attention has been paid to influence of stored lipids on uptake of xenobiotics. We drew upon principles of zooplankton population dynamics in the limnological literature to define experimental parameters for bioconcentration testing of organic compounds.

Adult test populations were initially starved and monitored for lipid content and brood production. Mean lipid index values declined at 72 h to less than 50% of those observed at 24 h. The number of hatched young peaked at 48 h and was inversely related to lipid storage and ovary production. In a separate experiment, uptake kinetics of 14C-labelled quinoline were compared between two daphnid test groups with mean lipid scores of 5.4 and 2.8, respectively. Total radioactivity was significantly higher for the high lipid group at 8 h, and the coefficient of variation was lower. Estimated bioconcentration factors adjusted to dry weight were similar. Our studies indicated that lipid reserves of daphnid test populations can be routinely monitored as an indicator of stress in the laboratory. Bioaccumulation tests should be limited to less than 24 h to avoid depletion of lipid stores, which may cause increased variation in tissue concentration over time.
Appropriate Durations and Measures for Ceriodaphnia Toxicity Tests
Authors: McNaught DC , Mount DI
Published: December 2008

The objectives of this analysis of the Mount-Norberg Ceriodaphnia toxicity test were to improve its application to specific ecosystems and to shorten the duration required to obtain significant results. The three-brood seven-day toxicity test using Ceriodaphnia grown at 25°C became a 28-day test at 18°C. Using typical ecosystem temperature is an important aspect of this test when applied to specific locations. Generally Ceriodaphnia can be grown at temperatures of 12 to 25°C; too few neonates were produced at 6°C for useful test results. The synchronous release of neonates by parthenogenic females may be used in determining when to sample offspring and thus reduce the cost of testing complex effluents. The intrinsic growth rate r of these animals may be used instead of their net reproductive rate Ro to provide answers in a shorter time, with smaller coefficients of variation.
Physical/Chemical Properties of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin
Authors: Schroy JM , Hileman FD , Cheng SC
Published: December 2008

Limited and inaccurate physical property data for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have inhibited the development of good environmental transport and fate information for this material. Based on limited literature data and transport modelling techniques evaporation of 2,3,7,8-TCDD from the soil column was proposed as a major factor in its movement in the environment. Estimated physical properties data were used to focus field sampling and analytical work and to identify the key physical property parameters that required quantification. Initial predictions indicating soil column loss via evaporation have been confirmed, losses via evaporation have been confirmed, and a set of physical properties suitable for environmental transport modelling have been compiled.
Bioconcentration of Four Chlorinated Dioxins By Rainbow Trout and Fathead Minnows
Authors: Muir DCG , Yarechewski AL , Webster GRB
Published: December 2008

Accumulation of four 14C-labelled chlorinated dibenzo-p-dioxins (1,2,3,7-tetrachloro- (T4CDD), 1,2,3,4,7-pentachloro- (P5CDD), 1,2,3,4,7,8-hexachoro- (H6CDD), and 1,2,3,4,6,7,8-heptachloro- (H7CDD) isomers) from water by rainbow trout fry (Salmo gairdneri) and fathead minnows (Pimephales promelas) was studied using a 5-day exposure period followed by a 24-day elimination phase. Water concentrations of these hydrophobic compounds (measured after centrifugation) ranged from 0.005 to 0.10 ng/mL during the fish exposures. Equilibrium bioconcentration factors calculated by use of a two-compartment kinetic rate model ranged from 810 for P5CDD to 2278 for H6CDD in rainbow trout and from 515 for H7CDD to 4232 for H6CDD in fathead minnows. Elimination rates of T4CDD and P5CDD isomers were similar and rapid, with half-lives of total radioactivity averaging about 2.6 days in trout fry and 3.0 days in minnows. Half-lives of total 14C for H6CDD and H7CDD were also similar but much longer than the other two isomers averaging about 16 days in rainbows and 20 days in fatheads. Low bioconcentration by both species was attributed to the high proportion of total radioactivity in water apparently unavailable to the fish because of association with suspended and dissolved material and to poor membrane transport.
Developing an Accelerated Test: Problems and Pitfalls
Authors: Ketcham SJ , Jankowsky EJ
Published: December 2008

Naval aircraft spend considerable time on the decks of aircraft carriers exposed to sea spray and sulfur-bearing stack gases. A series of exposure tests of various aircraft materials and coatings have been conducted on operational carriers for over five years. There were two objectives for this work: (1) to find out how the materials behaved in the hostile carrier environment and (2) to develop a laboratory test to simulate that environment. The first objective is being successfully met. The second objective is more difficult to achieve.

To date, experiments have included use of a salt fog chamber with periodic introduction of sulfur dioxide gas. Various cyclic conditions have been studied. such as spraying salt fog, introducing sulfur dioxide gas followed by a soak period at high humidity. This cycle reproduces in two weeks the exfoliation attack on susceptible aluminum alloys that occur on a carrier in about eight months. However on cadmium plated steel, which undergoes little or no attack on the carrier, this cycle causes considerable attack on the coating. Since an accelerated test is also desired for materials, such as paints, corrosion preventive compounds, sealants, and other organics used on naval aircraft, finding one accelerated test that will reproduce carrier results on such a wide variety of materials presents a formidable task.
Microcomputer Data Acquisition for Corrosion Research
Authors: Tipton DG
Published: December 2008

Computer data acquisition in the corrosion laboratory is described. These techniques can provide higher resolution and be less labor intensive, faster, and more interactive than conventional data recording. Typical system design, component description and specification, interfacing, signal processing, and software considerations are presented. Several examples of computer data acquisition systems (DAS) in corrosion research applications are given.
An Accelerated Simulated Can Corrosion Test for Tinplate
Authors: Warwick ME , Hampshire WB
Published: December 2008

The internal corrosion of tinplate and lacquered tinplate containers is extremely complex and is a function of many interacting parameters. Electrochemical tests give an insight to the main reaction pathways controlling such corrosion but are not widely applicable to real situations. Industry is forced to rely on expensive and time-consuming pack tests when contemplating changes in either the design of the container or the characteristics of the product packed.

This paper describes an accelerated test that takes the form of a simulated can, which has been developed and used at the International Tin Research Institute over the last decade. The results of investigations into particular aspects of tinplate corrosion using this test are described and related to industrial experience with real containers. Providing care is taken in the interpretation of results, it is felt that the accelerated test provides a reliable way of reducing the need for pack testing.
Applications of Electrochemical Techniques in Screening Metallic-Coated Steels for Atmospheric Use
Authors: Berke NS , Friel JJ
Published: December 2008

Electrochemical tests were conducted on several aluminum-zinc-coated steels whose long-term atmospheric corrosion resistance is known in order to evaluate such tests as a screening technique. Linear polarization resistance measurements were made in aerated 1 N sodium chloride and 0.5 N sodium sulfate both at pH 4 to rank the different coatings and then compare this ranking with that found in marine and industrial environments. Weight loss was also measured, and the specimens were examined microscopically to verify the corrosion mechanism. Cathodic polarization tests were conducted in deaerated 1 N hydrochloric acid and 1 N sulfuric acid to examine a system with only one cathodic reaction. The results obtained in the pH 4 chloride and sulfate solutions were in good general agreement with the data from atmospheric exposures. Thus polarization resistance testing in 1 N sodium chloride and 0.5 N sodium sulfate at pH 4 shows promise as a screening technique for predicting the atmospheric corrosion resistance of metallic-coated steels.
Development of a Fluorescent Ultraviolet and Condensation Apparatus with a Light Energy Control System
Authors: Suga S
Published: December 2008

In order to improve the reproducibility of the alternate fluorescent ultraviolet (UV) and condensation test specified in ASTM Recommended Practice for Operating Light- and Water-Exposure Apparatus (Fluorescent UV-Condensation Type) for Exposure of Non-metallic Materials (G 53) the following modifications have been developed for the test apparatus: (1) fluorescent UV lamps are preconditioned and equipped with means to yield a stable radiant output during operational life; (2) all of the eight lamps that have been preconditioned and have similar characteristics in radiant output are installed in the apparatus at the same time; and (3) the lamp spacing and arrangement is modified and the light intensity is automatically controlled. By providing uniform distribution of irradiance with a constant level throughout the test period, these modifications improve the reproducibility of the test, increase acceleration, and facilitate operation.
Once Through Versus Recirculated Seawater Testing for Calcareous Deposit Polarization of Cathodically Protected Steel
Authors: Nye TL , Smith SW , Hartt WH
Published: December 2008

In seawater, cathodic protection systems for steel structures rely on the formation of a calcareous film to help polarize the surface and thereby reduce the current required to maintain the potential in the protection range. These models require experimental determination of the polarization behavior for the cathodically protected steel. The experiments have been carried out in a variety of electrolytes including artificial seawater, recirculated seawater, and once through fresh seawater. While the latter is obviously the preferred method, there are few research facilities capable of extensive testing in fresh flow-through seawater. This results in the use of the less preferred recirculated natural and artificial seawater procedures.

This paper presents the results of an investigation contrasting data obtained in a series of otherwise identical once-through and recirculating seawater experiments in which the current decay rates of cathodically protected steels were determined. The experiments were run in fresh Atlantic Ocean seawater at the Center for Marine Materials Laboratory at Florida Atlantic University and ASTM Specification for Substitute Ocean Water (D 1141) artificial seawater. Both once-through and recirculating experiments were run concurrently. Possible explanations for the observed polarization rate differences include the effect of dissolved organic carbons and ion depletion.
A Corrosiveness Test for Fibrous Insulations
Authors: Crume SV
Published: December 2008

This paper describes the original development work for an insulation corrosiveness test that is used to test a variety of blanket, loose fill, and rigid fibrous insulations. The test, which provides a relative comparison of insulation corrosiveness with that of an inert control material at elevated temperature and humidity conditions, is reliable and reproducible when properly performed. The test is useful as a product development tool to qualify new insulation products and product formulation changes. The test consists of placing insulation and specially cleaned cotton controls against metal coupons and exposing them to 49° C (120° F) and 95% relative humidity conditions. After exposure, the coupons are ranked in order of corrosiveness by a panel of judges. A nonparametric statistical method is used to identify insulations that are more corrosive than the inert control material. Condition of the metal surfaces, cleanliness of the inert cotton control material, and uniform contact of the insulation against the metal surfaces were three areas identified as critical in conducting the corrosion test.
Laboratory Corrosion Testing of Metals and Alloys in Environments Containing Hydrogen Sulfide
Authors: Mack RD , Wilhelm SM , Steinberg BG
Published: December 2008

In recent years, the production of oil and gas from reservoirs containing significant partial pressures of hydrogen sulfide has become economical. Hydrogen sulfide is a toxic and highly flammable gas. Containment of the production fluid is critical from the view of safety and economics. The corrosion of metals and alloys used in these production environments therefore presents a serious problem. This paper discusses the test methods used for the laboratory corrosion testing of metals and alloys in simulated production environments containing hydrogen sulfide. The discussion includes the selection of the test method, test environment, and safety precautions taken during testing.
Development of an Environmental Wear Corrosion Test for Coinage Materials
Authors: Baboian R , Haynes GS
Published: December 2008

An accelerated environmental wear test has been developed that duplicates the behavior of coins in circulation mechanistically as well as visually. The environmental wear properties of monometal copper coins and of copper clad steel coins are improved by addition of zinc or nickel to the copper to form brass or copper-nickel (CuNi) alloys. Noble metal clad steel coins have similar environmental wear resistance to their respective noble monometal coins.
Laboratory Tests for Corrosion of Steel in Concrete
Authors: Rosskopf PA , Virnelson RC
Published: December 2008

The development of laboratory test methods for determining potential corrosion of steel imbedded in portland cement mortars is described in detail. Examples are given of the effects of chemical admixtures on the passive iron hydroxide protective layer surrounding reinforcing steel in concrete. Specific examples are shown that identify a threshold limit below which known corrosive materials are inert with respect to steel in concrete.
Corrosion Induced Deformation Behavior of Brick Masonry Wall Panels
Authors: Dial SA , Carrasquillo RL , Breen JE
Published: December 2008

The main purpose of the work described herein was to study the magnitude of corrosion induced distress in brick masonry wall panels under service conditions in a structure exposed to an acid rain environment. For this purpose, some specimens were subjected to a constant sustained load during exposure testing typical of dead loading under service conditions.

Specimens consisted of nine masonry wall panels with a steel plate, representative of shelf angles used in construction, embedded in the mortar joints at the third and sixth courses. Following twelve weeks of strain readings after load application, an acid-water solution was sprayed on the face of the walls, and accelerated corrosion was electrically induced in the embedded steel plates. Corrosion was also induced in six steel plate specimens that were immersed in tubs filled with the acid-water solutions. Expansion strains and cracking caused by the corrosion of the embedded steel were recorded, and the weight loss of the steel plate specimens was measured. The corrosion products on the steel plates were analyzed under an electron microscope and using X-ray diffraction analysis.

The results show that the embedded plates do not affect the overall temperature and moisture deformation behavior of the wall panels except for local disturbances in the joints containing the plates. The plate regions in the loaded wall panels underwent larger creep strains than regions of the wall panels that did not contain embedded plates. The average creep strains for the loaded walls were 39% lower than the creep strains reported from a previous investigation using similar wall panels that did not contain embedded plates. The presence of the embedded plates appeared to decrease the magnitude and duration of creep.

The induced corrosion of the embedded steel plates caused expansion strains that were several orders of magnitude greater than the tensile strain of masonry at failure. The weight loss of the plates from the nonloaded walls generally was slightly greater than that of the plates from the loaded walls for similar exposure times and was approximately 50% less than the weight loss of the immersed plate specimens.
Jet-in-Slit Test for Studying Erosion-Corrosion
Authors: Matsumura M , Oka Y , Okumoto S , Furuya H
Published: December 2008

“Jet-in-slit” was used for erosion-corrosion tests on 6/4 yellow brass in a 3% sodium chloride solution together with free jet and submerged jet (common nozzle diameter of 1.6 mm). The latter jets are typical testing methods for evaluating the resistance of alloys to erosion-corrosion. Each specimen sustained a characteristic damage on its surface after 24-h running under common flow rate (0.4 L/min) of the test liquid. The most critical damage occurred on the jet-in-slit specimen.

Measurements through hydrodynamic as well as electrochemical techniques have proved that on a free jet specimen, the damage occurs only on the place of maximum shear stress, and on the submerged jet and jet-in-slit specimens occurs not only at the place of maximum shear stress but also at a place downstream where the flow velocity is considerably low but where impulsive pressure occurs intermittently. Based upon the experimental results obtained, the authors recommended the jet-in-slit for a standard testing method of erosion-corrosion resistance.
Slow Strain Rate Testing in High-Purity Water at Controlled Electrode Potentials
Authors: Rosborg B , Rosengren A
Published: December 2008

A closed-loop oxygen dosage and electrode potential control system has been designed for slow strain rate testing in high-purity water at controlled electrode potentials. It is used instead of a potentiostat in order to circumvent the experimental difficulty with an IR drop caused by the high resistivity of the environment. By means of this system slow strain rate testing of sensitized American Iron and Steel Institute (AISI) Type 304 (Unified Numbering System [UNS] 530400) stainless steel has been performed in high-purity high-temperature water at different electrode potentials, the occurrence of intergranular stress corrosion cracking being revealed by fractography. In this way the electrode potential below which intergranular stress corrosion cracking does not occur has been estimated; at 200°C a critical potential of −250 mV versus the standard hydrogen electrode (SHE) was obtained.
The Effect of Strain Rate on the Stress Corrosion Cracking of Steels for Prestressing Concrete
Authors: Sánchez Gálvez V , Caballero L , Elices M
Published: December 2008

The aim of the paper is to investigate the stress corrosion cracking behavior of prestressing steels under general practical conditions. An aqueous solution of calcium hydroxide with small additions of sodium chloride has been used, the pH being 12.5 and the potential −0.6-V standard calomel electrode (SCE) as well as −1.2-V (SCE). Both tension tests at constant load and constant strain rate have been performed on specimens precracked by fatigue. The experimental results show that the constant load test, as proposed by the Prestressing International Federation (FIP), may be improved by the constant slow strain rate test in a realistic environment, needing a smaller number of tests and showing that in some cases fractures happen at stress intensity factor K1 values below the stress intensity threshold factor KISCC value as determined by a constant load test.
An Improved Intergranular Corrosion Test for HASTELLOY® Alloy C-276
Authors: Manning PE
Published: December 2008

Presently, the most widely used susceptibility test for intergranular corrosion of HASTELLOY® Alloy C-276 is the ferric sulfate-sulfuric acid test. The corrosion rate obtained by this test has uniform and intergranular corrosion components. The uniform corrosion rate, which is a function of minor variations in alloy chemistry, may easily mask the intergranular corrosion component of the overall corrosion rate. A new solution chemistry identified through laboratory tests resolves the problem and displays a step function response in corrosion rate when there are high levels of grain boundary precipitation. Over 700 production specimens have been comparatively tested in both solutions, spanning a time period of two years. The new test consistently detects undesirable microstructural conditions in HASTELLOY Alloy C-276 that, in many cases, are not detected by the ferric sulfate-sulfuric acid test.
Surface Preparation Requirements for ASTM A 262
Authors: Schluter JM , Chivinsky JA
Published: December 2008

Variations in the ASTM Recommended Practices for Detecting Susceptibility to Intergranular Attack in Stainless Steels (A 262), Practice A and C results, between the producer and purchaser of a heat of American Iron and Steel Institute (AISI) 304 L (Unified Numbering System [UNS] S30403) stainless steel, resulted in a round-robin test. The four laboratories involved (two producers and two purchaser locations) each prepared one-quarter of the specimens tested by each of the laboratories to the ASTM A 262 Practice A and C requirements. The resulting data indicated that a specific practice of surface preparation on the test specimens should be specified and mutually accepted by the participating laboratories. Variations in the amount of metal removed from the specimen's surface can make a pass/fail difference. The current specification does not require a specific surface preparation or point out the importance of a mutually accepted surface preparation. The parties involved in ASTM A 262 Practice C testing should be aware of the significant effects of surface preparation on the reproducibility of test data.
Diffusion Coefficients of Nickel and Silicon in Ion Irradiated Fe-20Cr-20Ni
Authors: Macht M-P , Müller A , Naundorf V
Published: December 2008

Diffusion coefficients of nickel and silicon in Fe-20Cr-20Ni under 300-keV Ni+ irradiation at temperatures between 293 and about 930 K with an ion flux of 6.3 × 1012 cm−2 · s−1 were measured with the SIMS technique. Results indicate that below about 700 K transport is dominated by athermal recoil mixing. At higher temperatures diffusion coefficients increase with increasing temperature. This temperature dependence is discussed with respect to point defect reactions and diffusion. The activation enthalpy of 0.67 eV for nickel diffusion in Fe-20Cr-20Ni is determined by half of the vacancy migration enthalpy. Diffusion coefficients of silicon in the alloy are about one order of magnitude larger than the nickel diffusion coefficients.
Effects of Anisotropic Diffusion on Irradiation Deformation
Authors: Woo C
Published: December 2008

Using the results of reaction kinetics controlled by anisotropic diffusion, this paper shows that the difference between the diffusional anisotropies of the vacancies and interstitials produces different sink strengths for the two kinds of point defects. The effects on irradiation deformation are investigated in terms of a generalized bias concept that depends not only on the point-defect/sink interaction, as in conventional theories, but also on the diffusional anisotropy difference. It is found that anisotropic diffusion adds a new dimension to the theory of irradiation deformation, which needs to be taken into account in the study of the underlying mechanisms.
Development of Modified Type 316 Stainless Steel for Fast Breeder Reactor Fuel Cladding Tubes
Authors: Fujiwara M , Uchida H , Ohta S , Yuhara S , Tani S , Sato Y
Published: December 2008

It is suggested from the understanding of the creep behavior in cold-worked austenitic stainless steels that high out-of-reactor creep strength correlates with superior inreactor swelling resistance. The additions of small amounts of boron, phosphorus, titanium, and niobium were found to be beneficial for the improvement of the creep strength of cold-worked Type 316 stainless steel. These additions caused finely dispersed precipitates in the grains during creep at elevated temperatures and resulted in retarding the recovery of the dislocation structures induced by cold working. The cold-worked modified Type 316 stainless steel having improved out-of-reactor creep strength showed excellent resistance to swelling. It is considered that higher stability of dislocation structures at elevated temperatures is also beneficial for the improvement of swelling resistance.
Neutron-Induced Swelling in Cold-Worked Titanium-Modified AISI 316 Alloys
Authors: Puigh RJ , Garner FA
Published: December 2008

In an earlier experiment it was shown that titanium additions tended to suppress swelling of American Iron and Steel Institute (AISI) 316 alloys in the annealed condition. Evidence is presented to show that a similar effect occurs in the cold-worked condition in both the Experimental Breeder Reactor (EBR-II) and the Fast Flux Test Facility (FFTF). The titanium-modified steels owe their improved swelling resistance not only to their titanium additions but also to small but significant changes in nickel, chromium, silicon and phosphorus levels.
Nucleation, Growth, and Distribution of Cavities in the Vicinity of Grain Boundaries in Aluminum Irradiated with 600-MeV Protons
Authors: Victoria M , Green WV , Singh BN , Leffers T
Published: December 2008

High-purity aluminum (99.9999%) was irradiated with 600-MeV protons with a damage rate of 3.5 × 10−6 dpa/s and a helium generation rate of 214 atomic parts per million (appm) per dpa. The irradiation experiments were carried out at temperatures in the range 120 to 140°C to doses up to 5 dpa. Transmission electron microscopy on irradiated specimens showed that voids are formed only in a narrow band in the vicinity of the void denuded zone along grain boundaries. Both the density and the size of voids in this band vary as a function of distance from the denuded zone. Changes in irradiation dose and temperatures do not seem to affect the spatial distribution of voids in the band. These results are compared with the results obtained on high-purity aluminum irradiated with fast neutrons. The bubble formation behavior in the grain interior and in the band containing voids is briefly described. The effect of bubble formation on the growth behavior of voids is discussed.
Dislocation Behavior in the Swelling Process of HVEM Irradiated Stainless Steel
Authors: Igata N , Kohno Y , Nishimura J
Published: December 2008

The objective of this study is to clarify the role of dislocations in the swelling process of high-voltage electron microscopy (HVEM) irradiated stainless steel. Solution annealed 304 stainless steels were irradiated and observed in-situ by means of HVEM in the temperature range of 673 to 873K. Swelling results were interpreted using the after-transient linear swelling model in all irradiations. Change of dislocation density was measured as a function of irradiation dose, and the dose for dislocation density saturation was found to correspond to the dose when swelling began to increase linearly in almost all cases. The saturated void number density was proved to be closely equal to the number density of dislocation loops formed in the early stage of irradiation, and in some cases, positional correspondence between them was also found. These phenomena suggest the possibility of void nucleation at initial dislocation loop sites.
Void Swelling in Electron-Irradiated Fe-Cr-Ni Model Alloys
Authors: Rotman F , Dimitrov O
Published: December 2008

A study of the void swelling produced by 1-MeV electron irradiation in high-purity Fe-Cr-Ni alloys has been performed in order to obtain a better understanding of the composition dependence of swelling in this system. Alloys with 16 wt% chromium and 20 to 75 wt% nickel, with or without helium preinjection, were irradiated in a high-voltage electron microscope, at a displacement rate of 22 dpa/h in the temperature range 370 to 600°C, to maximum damage levels up to 105 dpa. An increase in nickel concentration was found to reduce void density, to increase incubation dose, and to shift the swelling-rate maximum to lower temperatures. A helium preinjection of 70 appm reduces strongly the effect of material composition. The application of a simple void-growth model to the experimental results shows that the changes of point-defect parameters with nickel concentration produce variations of the calculated swelling rate that exhibit the observed trends. However these variations are of only marginal amplitude, as compared with the swelling-rate variations resulting from the observed microstructural changes. The bias factor was found to decrease with decreasing temperature in the 20 wt% Ni alloy; it also decreased at 500°C, with increasing nickel concentration.
Effect of Nickel Content on the Minimum Critical Void Radius in Ternary Austenitic Alloys
Authors: Coghlan WA , Garner FA
Published: December 2008

Swelling data from both ion and neutron irradiations of Fe-Cr-Ni alloys are analyzed in terms of the critical radius concept for bubble-to-void conversion. It is shown that while the dependence of critical radius on temperature, displacement rate, and helium can explain many features of the data, one must also consider the dependence of vacancy diffusion on nickel content in order to be able to explain the compositional dependence of void nucleation.
The Influence of Helium Trapping by Vacancies on the Behavior of Metals Under Irradiation
Authors: Murphy SM
Published: December 2008

Helium is readily trapped by vacancies, and this trapping reduces its mobility considerably. Trapping also influences the sink strengths of the sinks in the material, and in this paper we describe calculations for these sink strengths using a recently developed numerical method for calculating the concentration profiles around a sink embedded in a lossy continuum. We find that under some conditions the sink strengths can differ appreciably from the values for a noninteracting mobile defect. Using these sink strengths, we then discuss the effect of trapping on the effective diffusion coefficient of the helium. We find that the effective diffusion coefficient of the helium is very close to the value obtained when these changes to the sink strengths are neglected. This is because, in general, the sink strength for free helium atoms is increased whereas that for the trapped helium is decreased.
A Composite Model of Microstructural Evolution in Austenitic Stainless Steel Under Fast Neutron Irradiation
Authors: Stoller RE , Odette GR
Published: December 2008

A rate-theory-based model has been developed which includes the simultaneous evolution of the dislocation and cavity components of the microstructure of irradiated austenitic stainless steels. Previous work has generally focused on developing models for void swelling while neglecting the time dependence of the dislocation structure. These models have broadened our understanding of the physical processes that give rise to swelling, for example, the role of helium and void formation from critically-sized bubbles. That work has also demonstrated some predictive capability by successful calibration to fit the results of fast reactor swelling data. However, considerable uncertainty about the values of key parameters in these models limits their usefulness as predictive tools. Hence, the use of such models to extrapolate fission reactor swelling data to fusion reactor conditions is compromised.

The present work represents an effort to remove some of these uncertainties by self-consistently generating the time dependence of the dislocation structure, both faulted loops and network dislocations. The model's predictions reveal the closely coupled nature of the evolution of the various microstructural components and generally track the available fast reactor data in the temperature range of 350 to 700°C for doses up to 100 dpa. As the theoretical model has become more complex, parameter choices were constrained to a more limited range of values in order to obtain this agreement between theory and experiment. While the model remains approximate in many respects, it should ultimately provide a more useful tool for understanding microstructural evolution under irradiation and permit more confident predictions of void swelling in future fusion reactors.
The Effects of Applied Stress on the Irradiation Induced Microstructures of Dilute Nickel Alloys
Authors: Atkins T , McElroy RJ
Published: December 2008

A detailed transmission electron microscopy (TEM) study has been performed on Ni-2.48% Si alloy specimens irradiated, in the stressed and unstressed condition, to a dose of 0.2 dpa at 623 K, with 3.5-MeV protons in the Proton Irradiation Creep Facility on the Harwell 6-MeV Van de Graaff accelerator. The objective of the work was to obtain detailed information on the size distributions of Frank loops, the primary irradiation produced microstructural feature in this material, which could be compared directly with the measured irradiation creep behavior. Low dose irradiations have been employed in order to minimize loop-loop interactions and maintain the microstructural record.

Because of specimen to specimen temperature variations the main body of the analysis was performed on eight grains from a single TEM disk, cut from a creep specimen irradiated at 50 MPa. The effect of applied stress on loop size and planar loop densities was assessed by comparing data from randomly oriented grains with a single grain, which had equal resolved normal stresses on each of the four {111} planes.

The Frank loop density is greatest on {111} planes with the highest normal stress. The applied stress influences the partitioning of loops between the different {111} planes but does not influence the overall loop density or the loop size. The present results support the stress-induced preferred nucleation (SIPN) or stress assisted rotation model of irradiation creep and no evidence has been found for either the stress-induced preferred absorption (SIPA) or stress-induced climb and glide (SICG) models. Frank loops account for less than 25% of the measured strain. The discrepancy probably arises from the unexpectedly high density and large size of unfaulted 110 loops. Additional information is required on vacancy loops and unfaulted loops in order to resolve the discrepancy between estimated and measured strains.
Dislocation Evolution in Fe-10% Cr
Authors: Horton LL , Bentley J
Published: December 2008

The dislocation microstructure found in the binary ferritic alloy, Fe-10% Cr, has been characterized for damage levels ranging from 0.3 to 100 dpa. The specimens were irradiated at 850 K with a “triple beam” of He+, D+, and 4 MeV Fe++ ions. Transmission electron microscopy revealed that dislocation loops were dominant in the dislocation microstructure from 0.3 to 3 dpa. At 0.3 dpa the loops were round to slightly rectilinear in shape, whereas at higher doses the majority of the loops had a convoluted shape that indicated preferential growth in the 〈110〉 directions. Analyses showed that all of the loops at low doses and the convoluted loops at 3 dpa were near-edge interstitial loops with b = a〈100〉. At 3 dpa, round interstitial loops with b = a/2〈111〉 were also observed. Network segments with b = a/2〈111〉 were found at the intersection of a〈100〉 loops with a/2〈111〉 loops. At damage levels greater than 10 dpa, the structure consisted of a coarse distribution of network segments along with a few loops with b = a/2〈111〉. At 30 and 100 dpa a relatively low dislocation density, <1014 m−2, was found. The effects of segregation on the observed dislocations and the implications of the observations on the current understanding of dislocation evolution and damage mechanisms in ferritic materials are discussed.
In-Situ Electron Microscopy Observation of Dislocation Motion in 600-MeV Proton Irradiated Aluminum
Authors: Gavillet D , Green WV , Victoria M , Gotthardt R , Martin J-L
Published: December 2008

In-situ deformation experiments have been performed in a 100-keV transmission electron microscope on aluminum which had been preirradiated with 600-MeV protons to a damage level of 1 to 5 dpa. The proton irradiation also produced helium and spallation product impurities. The intent was to determine which feature present in the irradiated microstructure produced the radiation strengthening observed earlier. The microstructure features resolved before deformation included small helium bubbles and dislocations. In-situ stressing produced dislocation motion. In observations performed during stress relaxation, local dislocation curvature indicated local strengthening. The strongest type of dislocation barrier was a presumed submicroscopic cluster defect; the helium filled bubbles were less effective obstacles to dislocation motion.
Effects of Heavy-Ion Irradiation on HT-9 Ferritic Steel Examined in Cross Section
Authors: Kai J-J , Kulcinski GL , Dodd RA
Published: December 2008

Specimens of HT-9 have been irradiated with 14 MeV Ni+3 ions in the temperature range from 300 to 600°C and up to the peak damage level of 200 dpa. The specimens were prepared for transmission electron microscopy (TEM) studies using the cross-section technique that allows the whole damage region to be examined in a single foil. The most significant result of this study is that without prior implantation of helium gas atoms virtually no cavities were found in any of the irradiated specimens. Other microstructural features resulting from the irradiation were also examined in detail, including dislocation loops and precipitates. After irradiation at 300°C, the microstructure consisted of a very high number density of small dislocation loops. The average diameter of these loops is 8 nm and is relatively independent of the dose level. The number density of the loops saturates at higher dose levels. The microstructure after irradiation at 400°C is very similar to the 300°C case except that the average diameter of the dislocation loops is about 24 nm. However, a new phase forms at the end of the damage range during the irradiation at 400°C. The particle diameter of this new phase is about 5 nm, and it has been provisionally identified as α′ phase, which is a chromium enriched bcc phase. It forms largely in association with the dislocation loops. After irradiation at 500°C, the microstructure consisted of a few large dislocation loops, dislocation segments, and a group of new precipitates. The dislocation loops have the same characteristics as in the 300 and 400°C cases. The size of the loops is independent of dose level and about 100 nm in diameter, and the number density of the loops saturates at higher dose levels. The new phase has been identified as the Chi phase, which is an intermetallic phase with a bcc structure. The precipitates of Chi phase have the tendency to grow to larger diameter and the number density decreases with increasing dose levels. There is virtually no difference between the microstructure in irradiated and control regions after irradiation at 600°C. This result indicates that thermal effects dominate the microstructural evolution at this temperature and above in ion irradiated HT-9.
Evaluation of Ferritic Alloy Fe-2¼Cr-1Mo After Neutron Irradiation: Microstructural Development
Authors: Gelles DS
Published: December 2008

As part of a program to provide a data base on the bainitic alloy Fe-2¼Cr-1Mo for fusion energy applications, microstructural examinations are reported for nine specimen conditions for 2¼Cr-1Mo steel that had been irradiated by fast neutrons over the temperature range 390 to 510°C. Void swelling is found following irradiation at 400 to 480°C. Concurrently dislocation structure and precipitation developed. Peak void swelling, void density, dislocation density, and precipitate number density formed at the lowest temperature, approximately 400°C, whereas mean void size and mean precipitate size increased with increasing irradiation temperature. The examination results are used to provide interpretation of in-reactor creep, density change, and post irradiation tensile behavior.
Radiation-Induced Segregation in Cu-Au Alloys
Authors: Hashimoto T , Rehn LE , Okamoto PR
Published: December 2008

Radiation-induced segregation in a Cu-lat.% Au alloy was investigated using in-situ Rutherford backscattering spectrometry. Irradiation with 1.8-MeV helium produced nonequilibrium gold atom depletion in the near surface region. The amount of segregation was measured as a function of dose, dose rate, and temperature. Segregation was observed in the temperature range between about 300 and 500°C. For a calculated dose rate of 3.9 × 10−5 dpa/s, the radiation-induced segregation rate peaked near 400°C. Theoretical analysis based on the Johnson-Lam model predicted that the amount of segregation would be directly proportional to dose at the early stage of irradiation, would deviate from linearity with a continuously decreasing slope at intermediate doses, and finally approach a constant value after high doses. The analysis also predicted that the segregation rate would vary as the −¼th power of the dose rate at constant dose in the low temperature region. These predictions were all verified experimentally. A procedure for extracting relative defect production efficiencies from similar measurements is discussed.
Radiation-Induced Segregation and Precipitation in Molybdenum-Rhenium Alloys
Authors: Erck RA , Wayman CM , Rehn LE
Published: December 2008

Specimens of Mo-7 atomic % Re, Mo-27 atomic % Re, and Mo-30 atomic % Re were irradiated with 1.8-MeV 4He+ ions at elevated temperatures. Radiation-induced segregation of rhenium was measured during irradiation by in-situ Rutherford backscattering spectrometry (RBS). Segregation of the undersized rhenium atoms in the same direction as the defect fluxes, that is, toward the external surface, was observed. The amount of rhenium enrichment in the near-surface region was measured as a function of temperature and of dose at a calculated near-surface displacement rate near 1 × 10−4 dpa/s. Segregation was measured by RBS at temperatures from 800 to 1500°C in Mo-7Re, and from 850 to 1225°C in Mo-30Re.

Irradiated disks were examined by transmission electron microscopy. Chi phase precipitation was observed on grain boundaries, and at the irradiated surface in Mo-27Re and Mo-30Re after irradiation at temperatures from 750 to 1075°C. Chi precipitates formed with cube/cube and twin orientations with respect to the host matrix. No voids or loops were observed for ion doses up to 1.6 dpa.
The Influence of Electron Irradiation on the Structural State of γ-Fe-Mn Alloys
Authors: Mekhrabov AO , Binnatov KG , Mekhrabov AO , Shukyurov TA
Published: December 2008

The present paper considers the influence of irradiation by high-energy electrons on atomic distribution that is, short range order, of fcc Fe-Mn alloys. Using Mössbauer spectroscopy to measure the effective magnetic field distribution function, it has been shown that alloys with manganese concentration up to 45 atomic % electron irradiation decompose after leading to the formation of concentration inhomogeneities with regions depleted and enriched by manganese atoms. The atomic ordering process probably takes place in alloys almost equiatomic in composition.