Alloy 800 specifications in compliance with component requirements

International Nuclear Information System (INIS)

Diehl, H.; Bodmann, E.

1990-01-01

In view of the importance of the material Alloy 800 in high-temperature reactor plants (HTR), a material data bank was established which is used for statistical evaluation of mechanical and physical material behaviour. Based on investigations on the interconnection between the mechanical properties at high temperatures and the metallurgical parameters, different types of Alloy 800 were specified in compliance with the component requirements. In addition, aspects of corrosion and toughness behaviour were taken into consideration. The specifications and strength characteristics for the different variants of Alloy 800 were incorporated into draft DIN standards after discussion and approval in expert committees. Further important characteristics of the mechanical and physical material behaviour were summarized in HTR material data sheets so as to furnish an improved basis for the design and stress analyses of Alloy 800 components. (orig.)

Progressive degradation of alloy 690 and the development of a significant improvement in alloy 800CR

International Nuclear Information System (INIS)

Staehle, Roger W.; Arioka, Koji; Tapping, Robert

2015-01-01

The present most widely used alloys for tubing in steam generators and structural materials in water cooled reactors are Alloy 690 and Alloy 800. However, both alloys, while improved over Alloy 600 may not meet the needs of longer range applications in the range of 80-100 years. Alloy 690 sustains damage resulting from the formation of cavities at grain boundaries which eventually cover about 50% of the area of the grain boundaries with the remainder covering being covered with carbides. The cavities seem to nucleate on the carbides leaving the grain boundaries a structure of cavities and carbides. Such a structure will lead the Alloy 690 to fail completely. Normal Alloy 800 does not produce such cavities and probably retains a large amount of its corrosion resistance but does sustain progressive SCC at low rate. A new alloy, 800CR, has been developed in a collaboration among Arioka, Tapping, and Staehle. This alloy is based on a Cr composition of 23.5-27% with the remainder retaining the previous Alloy 800 composition. 800CR sustains a crack velocity about 100 times less than Alloy 690 and a negligible rate of initiation. The 800CR, alloy is now seeking a patent. (authors)

Creep and fatigue of alloy 800 in helium

International Nuclear Information System (INIS)

Cook, R.H.

1975-01-01

Proposals for use of Alloy 800 as a H.T.R. boiler material have prompted studies of its creep and high temperature fatigue properties in impure helium with comparative tests in air. In impure helium, as expected in a H.T.R., reactions of potential importance are selective oxidation (of chromium, aluminium and titanium) and possibly carburisation from carbon monoxide or methane. In air, general oxidation will occur, possibly accompanied by nitridation. The effects of these reactions will depend on specimen geometry and the nature of the deformation. Two important possibilities are: (i) that environment affects the structure and properties of a surface zone of material undegoing uniform deformation (this may modify creep rate and crack nucleation); and (ii) that environment affects behaviour of a small region (e.g. at the root of a notch or ahead of a crack) in a specimen undergoing non-uniform deformation (this will modify crack growth and hence rupture life or fatigue endurance). This paper summarises experimental work demonstrating an influence of the above reactions on mechanical properties of austenitic steels and nickel-based alloys, drawing examples where possible from the limited data available on Alloy 800. Whilst nitridation and carburisation may simply increase creep resistance at the expense of ductility (and possibly of fatigue resistance), the effects of oxidation are complex. A high oxygen pressures (as in air) oxygen may reduce creep and fatigue resistance by promoting cavitation but formation of oxide in cracks can reduce their propagation rate. At low oxygen pressures, as expected in H.T.R. helium, oxygen enhanced cavitation is less likely, but selective oxidation along grain boundaries can sometimes assist crack nucleation. (author)

Studies on the growth of oxide films on alloy 800 and alloy 600 in lithiated water at high temperature

International Nuclear Information System (INIS)

Olmedo, A.M.; Bordon, R.

2007-01-01

In this work, the oxide films grown on Alloy 800 and Alloy 600 in lithiated (pH 25 C d egrees = 10.2-10.4) water at high temperature, with and without hydrogen overpressure (HO) and an initial oxygen dissolved in the water have been studied. The oxide films were grown at different temperatures (220-350 C degrees) and exposure times with HO, and at 315 C degrees without HO in static autoclaves. Some results are also reported for oxide layers grown on Alloy 800 coupons exposed in a high temperature loop during extended exposure times. The average oxide thickness was determined using descaling procedures. The morphology and composition of the oxide films were analyzed with scanning electron microscopy (SEM), EDS and X-ray diffraction (XRD). For both Alloys, at 350 C degrees with HO, the oxide layers were clearly composed of a double layer: an inner one of very small crystallites and an outer layer formed by bigger crystals scattered over the inner one. The analysis by X-ray diffraction indicated the presence of spinel structures like magnetite (Fe 3 O 4 ) and ferrites and/or nickel chromites. In this case the average oxide thickness was around 0.12 to 0.15 μm for both Alloys. Similar values were found at lower temperatures. The morphology of the oxide layer was similar at lower temperatures for Alloy 800, but a different morphology consisting of platelets or needles was found for Alloy 600. The oxide morphology found at 315 C degrees, without HO and with initial dissolved oxygen in the water, was also very different between both Alloys. The oxide film grown on Alloy 600 with an initial dissolved oxygen in the water, showed clusters of platelets forming structures like flowers that were dispersed on an rather homogeneous layer consisting of smaller platelets or needles. The average oxide film grown in this case was around 0.25 μm for Alloy 600 and 0.18 μm for Alloy 800. (author) [es

Effect of lead and silicon on localized corrosion of Alloy 800 in steam generator crevice environments

International Nuclear Information System (INIS)

Lu, Y.C.; Wright, M.D.; Cleland, R.D.

2001-09-01

The Alloy 800 tubes used in CANDU 6 steam generators have not experienced significant corrosion damage to date, which may be attributed to successful water chemistry control strategies. However, it is known that Alloy 800, like other steam generator (SG) tubing materials, is not immune to corrosion, especially pitting, under some plausible but off-specification operating scenarios. Electrochemical measurements provide information on corrosion susceptibility and rate, which are known to be a function of water chemistry. Using laboratory data in combination with chemistry monitoring and diagnostic software it is possible to assess the impact of plant operating conditions on SG tube corrosion for plant life management (PLIM). In this context, this paper discusses the results of electrochemical measurements made to elucidate the corrosion behaviour of Alloy 800 SG tubes under conditions simulating those plausible in SG crevices. In addition to crevice pH, the influence of PbO, acting alone or in combination with SiO 2 , on localized corrosion such as pitting or stress corrosion-cracking (SCC) was determined. Possible transient chemistry regimes that could significantly shorten expected tube lifetimes have been identified from the data analysis. Of equal significance, the results also support the position that under normal, near neutral pH and low dissolved oxygen conditions, pitting and cracking of Alloy 800 steam generator tubing will not be initiated. (author)

Qualification of Alloy 800 for sodium heated steam generators

International Nuclear Information System (INIS)

Duke, J.M.; Sessions, C.E.; Ray, W.E.

1976-01-01

A reference specification of Alloy 800 for use in LMFBR steam generators is defined considering waterside corrosion, weldability and mechanical properties. Additional mechanical test data are being generated to support ASME Code acceptance. Candidate weld filler metals were assessed for use in subsequent weld process development. Progress on resolving technical concerns related to the role of tertiary creep identified the impact of test conditions and gamma prime strengthening in determining the creep behavior of Alloy 800

Study of Oxide Formation on Alloy 800 by Potentiostatic Polarization

Energy Technology Data Exchange (ETDEWEB)

Jung, Chong Hun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Momenib, M.; Wren, C. J. [University of Western Ontario, London (Canada)

2015-10-15

The objectives of study are to investigate the effect of potential on oxide formation and conversion on alloy 800 under potentiostatic conditions. For this study we have focused primarily on corrosion at pH{sub 25.}deg. C8.4. The results presented in Figures 1 show that in the range from -0.8 V{sub SCE} to +0.2 V{sub SCE} there are four potential regions having distinctly different short- and long-term characteristics in the log |i| vs. log t and Q vs. t plots. At a potential below -0.8 V{sub SCE}, the current becomes cathodic immediately (< 10 s) upon polarization, indicating negligible metal oxidation and hence is not of interest. In nuclear power plants, it is used for steam generator tubing in pressurized water reactors (PWRs), including Canadian Deuterium Uranium (CANDU) reactors. However, failures resulting from localized corrosion such as pitting, crevice and stress corrosion cracking (SCC) have been observed in the service environments. There exists still considerable controversy over the type of oxide that can be formed and the mechanism of oxide formation on Alloy 800.

Corrosion behavior of alloy 800H (Fe-21Cr-32Ni) in supercritical water

International Nuclear Information System (INIS)

Tan, L.; Allen, T.R.; Yang, Y.

2011-01-01

Research highlights: → Testing conditions and sample microstructures showed effects on corrosion behaviors. → EBSD and FIB/TEM were used to characterize microstructure in addition to SEM/EDS and XRD. → The formation mechanism of mushroom-shaped oxidation is proposed. → Oxidation thermodynamics and kinetics predict and interpret the corrosion behaviors. - Abstract: The effect of testing conditions (temperature, time, and oxygen content) and material's microstructure (the as-received and the grain boundary engineered conditions) on the corrosion behavior of alloy 800H in high-temperature pressurized water was studied using a variety of characterization techniques. Oxidation was observed as the primary corrosion behavior on the samples. Oxide exfoliation was significantly mitigated on the grain boundary engineered samples compared to the as-received ones. The oxide formation, including some 'mushroom-shaped oxidation', is predicted via a combination of thermodynamics and kinetics influenced by the preferential diffusion of specific species using short-cut diffusion paths.

Tritium Permeability of Incoloy 800H and Inconel 617

Energy Technology Data Exchange (ETDEWEB)

Philip Winston; Pattrick Calderoni; Paul Humrickhouse

2012-07-01

Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

Tritium Permeability of Incoloy 800H and Inconel 617

Energy Technology Data Exchange (ETDEWEB)

Philip Winston; Pattrick Calderoni; Paul Humrickhouse

2011-09-01

Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

A survey on the corrosion susceptibility of Alloy 800 CANDU steam generator tubing materials

International Nuclear Information System (INIS)

Lu, Y.C.; Dupuis, M.; Burns, D.

2008-01-01

To provide support for a proactive steam generator (SG) aging management strategy, a survey on the corrosion susceptibility of the archived Alloy 800 tubing from CANDU SGs under plausible crevice chemistry conditions was conducted to assess the potential material degradation issues in CANDU SGs. Archived Alloy 800 samples were collected from four CANDU utilities. High-temperature electrochemical analysis was carried out to assess the corrosion susceptibility of the archived SG tubing under simulated CANDU crevice chemistry conditions at both 150 o C and 300 o C. The potentiodynamic polarization results obtained from the archived CANDU SG tubes were compared to the data from ex-service tubes removed from Darlington Nuclear Generating Station (DNGS) SGs and a reference nuclear grade Alloy 800 tubing. It was found that the removed Darlington SG tubes, with signs of in-service degradation, were more susceptible to pitting corrosion than the reference nuclear grade Alloy 800 tubing. At 150 o C, under the same neutral crevice chemistry conditions, the potentiodynamic polarization curve of the ex-service Darlington SG tubing has an active peak, which is a sign of propensity to crevice/underdeposit corrosion. This active peak was not observed in any of the potentiodynamic polarization curves of all archived Alloy 800 CANDU SG tubing indicating that archived CANDU SG tubes are less susceptible to the underdeposit corrosion under SG startup conditions. The corrosion behaviour of the archived Alloy 800 tubes from CANDU SG was similar to that of the reference nuclear grade Alloy 800 tubing. The results of this survey suggest that the Alloy 800 tubing materials used in the existing CANDU utilities (other than ex-service DNGS tubing) will continue to have reliable performance under specified CANDU operating conditions. Ex-service SG tubing from DNGS, although showing lower than average corrosion resistance, still has a wide acceptable operating margin and the in

Effect of different ions on the anodic behaviour of alloy 800 chloride solutions at high temperature

International Nuclear Information System (INIS)

Lafont, C.J.; Alvarez, M.G.

1993-01-01

The anodic behaviour and passivity breakdown of alloy 800 in sodium bicarbonate and sodium phosphate aqueous solutions were studied in the temperature range from 100 degrees C to 280 degrees C by means of electrochemical techniques. The effect of phosphate or bicarbonate additions on the pitting susceptibility and pitting morphology of the alloy in chloride solutions was also examined. Experiments were performed in the following solutions: 0.1M NaHCO 3 , at 100 degrees C, 200 degrees C, 280 degrees C; 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 , at 100 degrees C, 200 degrees C and 280 degrees C, and 0.1M NaCl with different additions of bicarbonate ion (0.02M, 0.05M and 0.1M) and phosphate ion (0.01M, 0.05M and 0.1M) at 100 degrees C and 280 degrees C. The anodic polarization curves of alloy 800 in deaerated 0.1M NaHCO 3 and 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 solutions exhibited a similar shape at all the tested temperatures. No localized or generalized corrosion was detected on the metallic surface after polarization. The results obtained in chloride plus bicarbonate and chloride plus phosphate mixtures showed that the pitting potential of alloy 800 in chloride solutions was increased by the presence of bicarbonate or phosphate ions. In those solutions where the inhibitor concentration in the mixture is equal or higher than the chloride concentration , the behaviour of the alloy is similar to the one observed in the absence of chlorides. Changes in pitting morphology were found in phosphate containing solutions, while the pits found in bicarbonate containing solutions were similar to those formed in pure chloride solutions. (author). 3 refs., 4 figs

The metallurgy of alloy 800

International Nuclear Information System (INIS)

Stone, P.G.; Orr, J.; Guest, J.C.

1975-01-01

Following a review of published information on the metallurgy of the iron/chromium/nickel system, attention is directed to the metallurgical significance of relatively minor compositional variations introduced in Alloy 800 to meet the stress corrosion requirements of the nuclear power industry. These include the effect of carbon, nitrogen, titanium, and aluminium restrictions in the context of Light Water Reactor, High Temperature Reactor, and Fast Reactor applications. Solubility effects are also considered in relation to heat treatment procedures, metallurgical phenomena, and associated properties. The aging behaviour is also discussed and related to fabrication and service performance; particularly stress rupture behaviour. The effect of strain at ambient and elevated temperatures on these aspects is indicated. (author)

Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: Electrochemical studies

International Nuclear Information System (INIS)

Olmedo, A.M.; Villegas, M.; Alvarez, M.G.

1996-01-01

The anodic behaviour and passivity breakdown of Alloy 800 in aqueous solutions of sodium chloride, sodium sulphate and sodium bicarbonate were studied by electrochemical techniques in the temperature range from 60 C to 280 C. The pitting resistance and pitting morphology of the alloy in chloride plus sulphate and chloride plus bicarbonate mixtures, at 60 C and 280 C, were also examined. Increasing bicarbonate or sulphate additions to chloride solutions shift the characteristic pitting potential of Alloy 800 to higher values, both at low and high temperatures. Changes in pitting morphology were observed in sulphate containing solutions while the morphology of the attack found in bicarbonate containing solutions was similar to that in pure chloride solutions. Finally, no localized or substantial generalized corrosion was detected in pure sulphate or bicarbonate solutions at any temperature. (orig.)

Creep and low cycles fatigue behaviour of inconel 617 and alloy 800H in the temperature range 1073-1223

International Nuclear Information System (INIS)

Yun, H.M.

1984-01-01

The creep rupture properties of high temperature alloys are being determined as part of the materials programme for the development of the high temperature, gas-cooled reactor (HTGR) as a source of nuclear process heat, especially for the gasification of lignite and coal. INCOLOY 800H AND INCONEL 617 have been tested in the temperature range from 1073 K to 1223 K in air as well as in helium with HTGR specific impurities. The static and dynamic creep behaviour of INCONEL 617 have been determined in constant load creep tests, relaxation tests and stress reduction tests. The results have been interpreted using the internal stress on the applied stress and test temperature was determined. In a few experiments the influence of cold deformation prior to the creep test on the magnitude of the internal stress was also investigated. (Author)

A review of the structural characteristics of alloy 800

International Nuclear Information System (INIS)

Orr, J.

1978-01-01

The published literature is reviewed and supplemented by current information from the author's laboratory, to show the influence of various compositional, heat treatment and thermomechanical factors on the structural characteristics of Alloy 800. The features discussed include carbon, aluminium, titanium and boron, solution treatment, ageing treatments with and without applied strain, and cold working. Examples of the aspects reviewed include the effect of heat treatment and service or testing temperature on the austenite grain size, and the relative importance of M 23 C 6 and TiC, the influence of carbon level on gamma prime, the effect of residual or steady stress combined with time at temperature on changes in carbide or gamma prime morphology, and on the appearance of sigma or other intermetallic phases. The questions posed by these features are discussed generally, in terms of their effect on the mechanical properties at ambient and elevated temperatures and on the time-dependent properties. The review also suggests areas where further research work is required on Alloy 800. (Auth.)

Degradation of Alloy 800 steam generator tubing and its long-term behaviour predictions for plant life management

International Nuclear Information System (INIS)

Lu, Y.C.; Tapping, R.L.; Pandey, M.D.

2009-01-01

Alloy 800 tubing has a good service record in steam generators (SGs) in both German pressurized water reactors and CANDU 6 reactors, however, a recent comprehensive examination of several ex-service SG tubes removed from Darlington Nuclear Generating Station (DNGS) found that these SG tubes (which had experienced shallow pitting in service) were more susceptible to pitting corrosion in laboratory tests than a reference nuclear grade Alloy 800 tubing under SG crevice chemistry conditions. This was an unexpected finding and has raised questions about possible effects of in-service 'aging' on SG tubing. In addition, there has also been recent evidence that a few Alloy 800 tubes have experienced stress corrosion cracking (SCC) in some German pressurized water reactors (PWRs), possibly after many years of degradation-free service, although the inspection history of these tubes is not available to confirm that the reported degradation initiated recently. These findings suggest that Alloy 800 tubing may have some aging degradation susceptibility after many years of service. To provide support for a proactive SG aging management, a survey on the corrosion susceptibility of the archived Alloy 800 tubing from CANDU SGs under plausible crevice chemistry conditions was conducted to assess the potential material degradation issues in CANDU SGs. Experimental work was also performed to investigate the root cause leading to Alloy 800 SG tubing degradation. The results from this study suggested that a combination of negative factors; aggressive chemistry resulting from impurity ingress into the secondary side of the SGs, elevated electrochemical corrosion potential (ECP) during SG transients and surface strain/plastic deformation, might have led to the degradation of the ex-service SG tubing. The studies have shown that each of these conditions in isolation does not cause degradation of Alloy 800 SG tubing; a synergistic combination of factors is required. The OPEX and experimental

Assessment of effects of Fort St. Vrain HTGR primary coolant on Alloy 800. Final report

International Nuclear Information System (INIS)

Trester, P.W.; Johnson, W.R.; Simnad, M.T.; Burnette, R.D.; Roberts, D.I.

1982-08-01

A comprehensive review was conducted of primary helium coolant chemistry data, based on current and past operating histories of helium-cooled, high-temperature reactors (HTGRs), including the Fort St. Vrain (FSV) HTGR. A reference observed FSV reactor coolant environment was identified. Further, a slightly drier expected FSV coolant chemistry was predicted for reactor operation at 100% of full power. The expected environment was compared with helium test environments used in the US, United Kingdom, Germany, France, and Japan. Based on a comprehensive review and analysis of mechanical property data reported for Alloy 800 tested in controlled-impurity helium environments (and in air when appropriate for comparison), an assessment was made of the effect of FSV expected helium chemistry on material properties of alloy 800, with emphasis on design properties of the Alloy 800 material utilized in the FSV steam generators

Study of Incoloy 800HT alloy tested by heat-cycling

International Nuclear Information System (INIS)

Velciu, L.; Meleg, T.; Pantiru, M.; Petrescu, D.; Voicu, F.

2016-01-01

This paper investigated Incoloy 800HT (UNS N08811) alloy after some heat-cycling tests. The study continues prior tests realized in INR Pitesti concerning utilization of some nickel-based alloys in the heat exchangers and steam generators construction. The thermal-cycling consist in a successive series of heating and cooling with some rates in a range temperature. Technical parameters of thermal cycling: 50 & 200 cycles, 25 °C/minute heating-cooling rate, temperature range 450-1000°C, and argon working medium. The analysis consisted in metallographic examination (microstructure), Vickers microhardness, and traction tests. The average grain size was determined by linear interception method (ASTM E-112). The micro hardness was calculated by the relationship of the device technical book. On the Strength-Deformation diagrams were obtained: tensile strength and elongation. The tested samples were compared with the ''as received'' material. The results showed a good metallographic and mechanical behaviour of Incoloy 800HT at these thermal-cycling tests. (authors)

Secondary side IGA/IGSCC of SG alloys 600, 690 and 800 : R and D program in EDF Laboratories

International Nuclear Information System (INIS)

Vaillant, F.; DeBouvier, O.; Bouchacourt, M.; Stutzmann, A.; Lemaire, P.

1998-01-01

Many steam generators (SGs) equipped with 'mill-annealed' (MA) Alloy 600 tubings suffer significant secondary side corrosion. Until now, no degradation has been observed with either Alloy 600 TT or Alloy 690 for new SGs. The understanding of IGA/SCC of Alloy 600 MA in plants and the development of predictive models have become an important challenge to assess the life span and to reduce the maintenance costs of SGs. As degradation occurs in crevice environments which are varied and little known, EDF has undertaken an important program to improve the knowledge of crevice environments which lead to cracking. Corrosion tests are performed on Alloys 600 MA (also on 600 TT) in various environments in order to reproduce the deposits and the cracking observed on pulled tubes in laboratory conditions. Other corrosion tests are conducted in environments containing some pollutants identified by analyses of secondary water after hideout-return (sulfates) or oxidizing compounds : the influences of pH and potential are evaluated on Alloy 600 (MA or TT) and also on Alloys 690 and 800. A comprehensive model is proposed using IGA/SCC results of Alloy 600 in caustic environments. The thermomechanical parameters of the tubes and the field environmental conditions, introduced in the model, confirm some important features of SGs tubings. The model will be improved to include other detrimental environments. It will provide a useful tool to predict the life span (then steam generator replacements) and to optimize the maintenance policy of SGs still equipped with Alloys 600 MA and particularly with 600 TT (frequency and best locations of inspections). Margins will also be assessed for new SGs equipped with Alloy 690, and a comparison will be performed with Alloy 800. (author)

Testing of degradation of alloy 800 H in impure helium at 760 °C

Czech Academy of Sciences Publication Activity Database

Berka, J.; Vilémová, Monika; Sajdl, P.

2015-01-01

Roč. 464, September (2015), s. 221-229 ISSN 0022-3115 Institutional support: RVO:61389021 Keywords : High temperature corrosion * impure helium * 800 H * Generation IV nuclear reactors Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 2.199, year: 2015 http://www.sciencedirect.com/science/article/pii/S0022311515002019#

Compatibility of potential containment materials with molten lithium hydride at 800 C

International Nuclear Information System (INIS)

Pawel, S.J.

1993-01-01

A series of compatibility experiments has been performed for several stainless steels, carbon steels, and a nickel-base alloy in molten lithium hydride at 800 C for comparison with previous experiments on type 304L stainless steel. The results indicate that the mechanism of corrosion is the same for each of 304L, 304, 316L, and 309 stainless steel and that very similar corrosion in molten LiH is expected for each stainless alloy. Deviation from parabolic kinetics at extended exposure time for each stainless alloy is attributed in part to weight gains associated with lithium penetration. Stabilized (Nb and Ti) low carbon (< 0.06%) steels are observed to be essentially inert in LiH at 800 C with stable carbides and no grain growth. Mild steel (type 1020) is decarburized rapidly and exhibits extensive grain growth in LiH at 800 C. Both steels exhibit weight gains during exposure to molten LiH that are also related in part to lithium penetration. Alloy X (UNS N06002) exhibits extreme corrosion with essentially linear kinetics and dissolution of nickel sufficient to form subsurface voids. (orig.)

Research on the hot deformation behavior of a Fe-Ni-Cr alloy (800H) at temperatures above 1000 °C

Science.gov (United States)

Cao, Yu; Di, Hongshuang

2015-10-01

Considering the pinning effect of fine carbides on grain boundaries, hot compression tests were performed above the dissolution temperature of Cr23C6 to investigate the hot deformation behavior of a Fe-Ni-Cr alloy (800H). The results show that the single peak stress associated with dynamic recrystalization (DRX) became more distinct at higher temperature and lower strain rate. The process of DRX was thoroughly stimulated when deformed above 1000 °C. Constitutive equations for hot deformation were established by regression analysis of conventional hyperbolic sine equation. The relationships between Zener-Hollomon parameter (Z) and the characteristic points of flow curves were established using the power law relation. Furthermore, kernel average misorientation (KAM) and grain orientation spread (GOS) were used to map the distribution of local misorientation and estimate the fraction of DRX, respectively. The critical strain and peak strain were used to predict the kinetics of DRX with the Avrami-type equation.

Analysis of incoloy 800ht alloy tested in thermal transient conditions

International Nuclear Information System (INIS)

Velciu, L.; Meleg, T.; Nitu, A.; Popa, L.

2015-01-01

This paper investigated Incoloy 800 HT alloy after following thermal transient tests: fast heating rates (50° and 90°C/minute) up to 1,000°C, maintaining this temperature level (0 and 60 minutes), furnace-cooling until 220°C, and then air-cooling. This alloy is one of the candidate materials for construction of the steam generators of the future NPP reactors. The analysis consisted in metallographic examination and traction tests. The samples were investigated using the Olympus GX 71 optical microscope, the OPL microdurometer with automatic cycle and WALTER BAI traction device. The average grain size was determined by linear interception method. The micro hardness was calculated by the relationship from the device technical book. On the traction diagrams were obtained: strength resistance (Rm), elongation at rupture (A) and elastic modulus (E). The tested alloy was compared with the ''as received'' material, and the results showed a good behavior of this alloy in the presented conditions. (authors)

Effect of aging and cold working on the high-temperature low-cycle fatigue behavior of alloy 800H. Part I. The effect of hardening processes on the initial stress--strain curve

International Nuclear Information System (INIS)

Villagrana, R.E.; Kaae, J.L.; Ellis, J.R.; Gantzel, P.K.

1978-01-01

The individual and combined effects of cold working (5 and 10%) and aging (4000 and 8000 h at 538 to 760 0 C) on the microstructure and high-temperature yield strength of alloy 800H have been investigated. The specimens were tested at the aging temperatures. During testing some of the specimens showed the phenomenon of serrated yielding. In order of importance, the principal hardening agents observed in this work were: cold work, the precipitation of Cr 23 C 6 at the grain boundaries, and, in some cases, the precipitation of a Perovskite-type γ' phase in the grain interiors

Relaxation and corrosion resistance of alloy 800 used for steam generator tubes of ship borne boilers

International Nuclear Information System (INIS)

Corrieu, J.M.; Cortial, F.; Maillard, J.L.; Vernot-Loier, C.; Lebeau, M.

1994-01-01

The INCO ''INCOLOY 800'' trademark groups the Fe-Cr-Ni alloys containing 30 to 35% nickel, 19 to 23% chromium, 0,15 to 0,60% aluminium, 0,15 to 0,60% titanium and less than 0,10% carbon contents, used as construction materials for condenser and heat exchanger tubes. In parallel with water chemistry control and studies aimed at reducing the residual stresses resulting from tube expansion, studies have been conducted to a better understanding of this alloy, its metallurgy and its corrosion behaviour under accurately defined fabrication and heat treatment conditions. The purpose of this paper is to present the results of a behaviour study of INDRET alloy 800 concerning isothermal relaxation and effects of the said relaxation heat treatments on alloy microstructure studied with a transmission electron-chemical method to determine the sensitiveness to intergranular corrosion, and by electrochemistry in pressurized hot water. (authors). 4 figs., 5 tabs., 7 refs

Bithermal and isothermal experimental test design and resulting influence on the pore formation during high-temperature-induced fatigue of the alloy 800 H

International Nuclear Information System (INIS)

Hurta, S.

1991-01-01

For investigating the damaging mechanism, bithermal TMF tests have been carried out with the alloy 800H, applying fast pressure half-cycles at low temperature (e.g. 300 C) and slow tensile phases at high temperature (e.g. 700 C). The experimental data thus obtained have been compared with the results of isothermal tests performed at 700 C. Most of the experiments have been performed stress-controlled and with a constant range of plastic strain. Under this regime, deformation is induced in the case of asymmetric test design within the tensile load phase, at various constant tensile stresses each, wheras in the compressive load phase, the stress is constantly increased for compressive stress-governed testing. The results obtained from both test types show that the type of compressive load phase is the factor governing the efficiency of pore formation. (orig.) [de

Improvement of the oxidation resistance of Tribaloy T-800 alloy by the additions of yttrium and aluminium

International Nuclear Information System (INIS)

Zhang, Y.-D.; Zhang, C.; Lan, H.; Hou, P.Y.; Yang, Z.-G.

2011-01-01

Research highlights: → The additions of yttrium (Y) reduced the oxidation rate of Tribaloy T-800 alloy. → Y promoted selective oxidation of Cr due to refinement of alloy phase size. → The oxidation rate was further reduced by Y plus Al with a protective Al 2 O 3 scale. → The positive effect of Y and Al being more pronounced at the higher temperature. - Abstract: The microstructures and oxidation behaviour of the modified Tribaloy T-800 alloys by additions of yttrium and yttrium plus aluminium have been studied. At the presence of yttrium alone, the oxidation rate decreased, and the selective oxidation of chromium was promoted, which was related to the refinement of alloy phase size. The addition of yttrium plus aluminium further reduced the oxidation rate. The selective oxidation of chromium and aluminium were both promoted significantly. The benefits were especially pronounced at 1000 o C, with the formation of protective alumina external layer and no internal oxides, which may be detrimental to the alloy mechanical property.

High-alloy steels and nickel alloys for construction of industrial plants. Pt. 2

International Nuclear Information System (INIS)

2007-01-01

Vol. 2 of the 8. Dresden Corrosion Protection Seminar comprises eight papers, most of which are in the form of PowerPoint presentations: High-temperature materials and their applications in chemical engineering (J. Kloever); Alloy 602 CA in metal dusting conditions; Material requirements in future power plants (H. Schneider); Status report on material qualification for the 700 C technology in coal power plants (R. Mohrmann); Materials for nuclear fusion (M. Paju); The degradation mechanism relaxation cracking as exemplified by the alloys 800 H and 617 (H.C. van Wortel); Specific requirements on the design of a pressurised manifold of Alloy 800 H in refineries, a case study (I. Rommerskirchen et al.); Materials for electro-surfacing for corrosion protection in conditions of high-temperature corrosion (M.Spiegel) [de

J-integral flaw resistance curves of Incoloy 800H at room temperature

International Nuclear Information System (INIS)

Krompholz, K.; Ullrich, G.

1985-08-01

J-integral experiments at room temperature were performed on three point bend type specimens of the iron-nickel base alloy Incoloy 800H with a/w-ratios of 0.3 and 0.5. These experiments are performed within the frame of a round robin test in cooperation with German- and US-partners. The tests were performed in stroke control as well as in load control. Three different evaluation procedures were applied: -The signal of the dc potential drop technique -The partial unloading procedure and -The multiple specimen technique. Evaluating the dc potential drop technique and the multiple specimen method delivered reasonable results while the partial unloading procedure failed. The different methods are discussed and fractographic results support these results under discussion. (author)

Deposition of magnetite particles onto alloy-800 steam generator tubes

Energy Technology Data Exchange (ETDEWEB)

Basset, M.; Arbeau, N.; McInerney, J.; Lister, D.H. [Univ. of New Brunswick, Dept. of Chemical Engineering, Fredericton, NB (Canada)

1998-07-01

Fouling is a particularly serious problem in the power generating industry. Deposits modify the thermalhydraulic characteristics of heat transfer surfaces by changing the resistance to heat transfer and the resistance to fluid flow, and, if thick enough, can harbour aggressive chemicals. Deposits are also implicated in the increase of radiation fields around working areas in the primary heat transfer systems of nuclear power plants. In order to understand the preliminary steps of the formation of corrosion product deposits on the outsides of steam generator tubes, a laboratory program has investigated the deposition of magnetite particles from suspension in water onto Alloy-800 surfaces under various conditions of flow, chemistry and boiling heat transfer. A recirculating loop made of stainless steel operating at less than 400kPa pressure, with a nominal coolant temperature of 90 degrees C, was equipped with a vertical glass column which housed a 2.5E-01m-long Alloy-800 boiler tube capable of generating a heat flux of 240kW/m{sup 2} . A concentration of suspended magnetite of 5.0E-03kg/m{sup 3} was maintained in the recirculating coolant, which was maintained at a pH of 7.5. The magnetite was synthesized with a sol-gel process, which was developed to produce reproducibly monodispersed, colloidal (<1{mu}m) and nearly spherical particles. A radiotracing method was used to characterize the deposit evolution with time and to quantify the removal of magnetite particles. The results from a series of deposition experiments are presented here. The deposition process is described in terms of a two-step mechanism: the transport step, involving the transport from the bulk of the liquid to the vicinity of the surface, followed by the attachment step, involving the attachment of the particle onto the surface. Under non-boiling heat transfer conditions, diffusion seems to be the dominant factor ruling deposition with a small contribution from thermophoresis; removal was

Deposition of magnetite particles onto alloy-800 steam generator tubes

International Nuclear Information System (INIS)

Basset, M.; Arbeau, N.; McInerney, J.; Lister, D.H.

1998-01-01

Fouling is a particularly serious problem in the power generating industry. Deposits modify the thermalhydraulic characteristics of heat transfer surfaces by changing the resistance to heat transfer and the resistance to fluid flow, and, if thick enough, can harbour aggressive chemicals. Deposits are also implicated in the increase of radiation fields around working areas in the primary heat transfer systems of nuclear power plants. In order to understand the preliminary steps of the formation of corrosion product deposits on the outsides of steam generator tubes, a laboratory program has investigated the deposition of magnetite particles from suspension in water onto Alloy-800 surfaces under various conditions of flow, chemistry and boiling heat transfer. A recirculating loop made of stainless steel operating at less than 400kPa pressure, with a nominal coolant temperature of 90 degrees C, was equipped with a vertical glass column which housed a 2.5E-01m-long Alloy-800 boiler tube capable of generating a heat flux of 240kW/m 2 . A concentration of suspended magnetite of 5.0E-03kg/m 3 was maintained in the recirculating coolant, which was maintained at a pH of 7.5. The magnetite was synthesized with a sol-gel process, which was developed to produce reproducibly monodispersed, colloidal (<1μm) and nearly spherical particles. A radiotracing method was used to characterize the deposit evolution with time and to quantify the removal of magnetite particles. The results from a series of deposition experiments are presented here. The deposition process is described in terms of a two-step mechanism: the transport step, involving the transport from the bulk of the liquid to the vicinity of the surface, followed by the attachment step, involving the attachment of the particle onto the surface. Under non-boiling heat transfer conditions, diffusion seems to be the dominant factor ruling deposition with a small contribution from thermophoresis; removal was considered

Processing and properties of Nb-Ti-based alloys

International Nuclear Information System (INIS)

Sikka, V.K.; Viswanathan, S.

1992-01-01

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep test at 650 C and 172 MPa was conducted on the base alloy which contained 40Nb-40Ti-10Al-10Cr. A second alloy was modified with 0.11 at. % carbon and 0.07 at. % yttrium. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1,100 C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400, 600, 700, 800, 900, and 1,000 C, and for the modified alloy at room temperature, 400, 600, 700, and 800 C. Oxidation tests on the base alloy and modified alloy, as measured by weight change, were carried out at 600, 700, 800, and 900 C. Both the base alloy and the modified alloy were extremely ductile and were cold rolled to the final sheet thickness of 0.8 mm without an intermediate anneal. The modified alloy exhibited some edge cracking during cold during cold rolling. Both alloys recrystallized at the end of a 0.5-h annealing treatment. The alloys exhibited moderate strength and oxidation resistance below 600 C, similar to the results of alloys reported in the literature

Crack growth under combined creep and fatigue conditions in alloy 800

International Nuclear Information System (INIS)

Pfaffelhuber, M.; Roedig, M.; Schubert, F.; Nickel, H.

1989-08-01

To investigate the crack growth behaviour under combined creep-fatigue loading, CT 25 mm-specimens of X10NiCrAlTi 32 20 (Alloy 800) have been tested in experiments with cyclic loadings and hold times, with static loadings and short stress rekief interrupts, with ramp type loadings and with sequences of separate fatigue and creep crack growth periods. The test temperature of 700deg C was selected because only in this temperature range this alloy provides similar amounts of crack growth under creep and fatigue conditions due to equivalent stress levels. For the estimation of crack growth under combined loading conditions a linear accumulation of increase in crack length was proved using the crack growth laws of pure creep and fatigue crack growth. Hold time and ramp loadings lead to a higher crack growth rate compared with pure creep or pure fatigue crack growth tests. In hold time experiments the crack growth rate is higher than ramp tests of the same period time. The results of hold time tests can be fairly enough predicted by linear damage accumulation rules. (orig.) [de

Microstructural features of dissimilar welds between 316LN austenitic stainless steel and alloy 800

International Nuclear Information System (INIS)

Sireesha, M.; Sundaresan, S.

2000-01-01

For joining type 316LN austenitic stainless steel to modified 9Cr-1Mo steel for power plant application, a trimetallic configuration using an insert piece (such as alloy 800) of intermediate thermal coefficient of expansion (CTE) has been sometimes suggested for bridging the wide gap in CTE between the two steels. Two joints are thus involved and this paper is concerned with the weld between 316LN and alloy 800. These welds were produced using three types of filler materials: austenitic stainless steels corresponding to 316,16Cr-8Ni-2Mo, and the nickel-base Inconel 182 1 . The weld fusion zones and the interfaces with the base materials were characterised in detail using light and transmission electron microscopy. The 316 and Inconel 182 weld metals solidified dendritically, while the 16-8-2(16%Cr-8%Ni-2%Mo) weld metal showed a predominantly cellular substructure. The Inconel weld metal contained a large number of inclusions when deposited from flux-coated electrodes, but was relatively inclusion-free under inert gas-shielded welding. Long-term elevated-temperature aging of the weld metals resulted in embrittling sigma phase precipitation in the austenitic stainless steel weld metals, but the nickel-base welds showed no visible precipitation, demonstrating their superior metallurgical stability for high-temperature service. (orig.)

Compatibility of heat resistant alloys with boron carbide, 5

International Nuclear Information System (INIS)

Baba, Shinichi; Kurasawa, Toshimasa; Endow, Taichi; Someya, Hiroyuki; Tanaka, Isao.

1986-08-01

This paper includes an experimental result of out-of-pile compatibility and capsule design for irradiation test in Japan Materials Testing Reactor (JMTR). The compatibility between sheath material and neutron absorber materials for control rod devices (CRD) was examined for potential use in a very high temperature reactor (VHTR) which is under development at JAERI. The purpose of the compatibility tests are preliminary evaluation of safety prior to irradiation tests. Preliminary compatibility evaluation was concerned with three items as follows : 1) Lithium effects on the penetrating reaction of Incoloy 800H alloy in contact with a mixture of boronated graphite and lithium hydroxide powders, 2) Short term tensile properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite and fracture mode analysis, 3) Reaction behavior of both alloys under transient power conditions of a VHTR. It was clear that the reaction rate constant of the Incoloy 800H alloy was accelerated by doping lithium hydroxide into the boron carbide and graphite powder. The mechanical properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite were decreased. Ultimate tensile strength and tensile ductilities at temperatures over 850 deg C were reduced, but there was no change in the proof (yield) stress. Both alloys exhibited a brittle intergranular fracture mode during transient power conditions of a VHTR and also exhibited severe penetration. Irradiation capsules for compatibility test were designed to simulate three irradiation conditions of VHTR: 1) steady state for VHTR, 2) Transient power condition, 3) Service limited life of CRD. Capsule irradiation experiments have been carried out satisfactorily and thus confirm the validity of the capsule design procedure. (author)

Corrosion of superalloy Incoloy 800H/HT in eutectic mixture LiF-NaF-KF with different addition of chromium fluoride; Korozia superzliatiny Incoloy 800H/HT v eutektickej zmesi LiF-NaF-KF s ruznym pridavkom fluoridu chromiteho

Energy Technology Data Exchange (ETDEWEB)

Kontrik, M.; Pavlik, V.; Simko, F. [Slovenska Akademia Vied, Ustav Anorganickej Chemie, Oddelenie Taveninovych Sustav, 84636 Bratislava (Slovakia)

2013-04-16

Thesis deals with investigating the addition of chromium trifluoride to eutectic mixture of LiF-NaF-KF (46.5 - 11.5 - 42 mol %) on the corrosion of superalloy Incoloy 800H/HT with static tests. The corrosion losses of the alloy and type of corrosion attack was observed. It was found that the addition of chromium fluoride into the mixture generally increases of corrosion of the material. Several types of corrosion attacks were observed. On the surface of the samples the spotted, pitting and transgranular corrosions were found. On the cross-sections of the samples the subsurface and lamellar corrosions were detected. (authors)

Some factors influencing the creep behaviour of alloy 800

International Nuclear Information System (INIS)

Asbury, F.E.; Willoughby, G.

1975-01-01

Studies have been made of the stability of the creep behaviour of two commercial casts of Incoloy 800, one high carbon and the other low carbon. The effects of pre-ageing, of prolonged creep up to 10 4 hours duration, and of grain size were investigated. Three factors were found to excercise a major influence on creep behaviour. Firstly, when the high carbon alloy was heat treated at 1150degC super-saturation effects, ascribed principally to carbon, gave some initial strengthening which would not, however, persist for the duration of service life in nuclear power plant applications above 600degC. Secondly, a gamma-dash type phase precipitated readily at 550 to 600degC, giving a marked increase in creep strength. Nucleation was sluggish at higher temperatures but once established, this form of strengthening could persist up to at least 650degC. Creep under non-isothermal conditions at 600 to 700degC would be complex on account of the behaviour of this phase. The hardening associated with its precipitation was greater in the low carbon alloy. Finally it was demonstrated that, in spite of gamma-dash precipitation, fine grained low carbon material was weak in creep at low stresses and temperatures. This was ascribed to the occurrence of grain boundary diffusion creep. It appears that this source of weakening would persist in service, and severely restrict the maximum temperature of usage for fined grained high tensile material. (author)

Investigation of creep rupture properties in air and He environments of alloy 617 at 800 °C

Energy Technology Data Exchange (ETDEWEB)

Kim, Woo-Gon, E-mail: wgkim@kaeri.re.k [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ekaputra, I.M.W.; Park, Jae-Young [Pukyong National University, Busan 608-739 (Korea, Republic of); Kim, Min-Hwan; Kim, Yong-Wan [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

2016-09-15

Creep rupture properties for Alloy 617 were investigated by a series of creep tests under different applied stresses in air and He environments at 800 °C. The creep rupture time in air and He environments exhibited almost similar life in a short rupture time. However, when the creep rupture time reaches above 3000 h, the creep life in the He environment reduced compared with those of the air environment. The creep strain rate in the He environment was a little faster than that in the air environment above 3000 h. The reduction of creep life in the He environment was due to the difference of various microstructure features such as the carbide depleted zone, oxidation structures, surface cracking, voids below the surface, and voids in the matrix in air and He environments. Alloy 617 followed Norton’s power law and the Monkman–Grant relationship well. As the stress decreased, the creep ductility decreased slightly. The thickness of the outer and internal oxide layers presented the trend of a parabolic increase with an increase in creep rupture time in both the air and He environments. The thickness in the He environment was found to be thicker than in the air environment, although pure helium gas of 99.999% was used in the present investigation. The differences in the oxide-layer thickness caused detrimental effects on the creep resistance, even in a low oxygen-containing He agent.

Investigation of creep rupture properties in air and He environments of alloy 617 at 800 °C

International Nuclear Information System (INIS)

Kim, Woo-Gon; Ekaputra, I.M.W.; Park, Jae-Young; Kim, Min-Hwan; Kim, Yong-Wan

2016-01-01

Creep rupture properties for Alloy 617 were investigated by a series of creep tests under different applied stresses in air and He environments at 800 °C. The creep rupture time in air and He environments exhibited almost similar life in a short rupture time. However, when the creep rupture time reaches above 3000 h, the creep life in the He environment reduced compared with those of the air environment. The creep strain rate in the He environment was a little faster than that in the air environment above 3000 h. The reduction of creep life in the He environment was due to the difference of various microstructure features such as the carbide depleted zone, oxidation structures, surface cracking, voids below the surface, and voids in the matrix in air and He environments. Alloy 617 followed Norton’s power law and the Monkman–Grant relationship well. As the stress decreased, the creep ductility decreased slightly. The thickness of the outer and internal oxide layers presented the trend of a parabolic increase with an increase in creep rupture time in both the air and He environments. The thickness in the He environment was found to be thicker than in the air environment, although pure helium gas of 99.999% was used in the present investigation. The differences in the oxide-layer thickness caused detrimental effects on the creep resistance, even in a low oxygen-containing He agent.

Characterization of Elevated Temperature Properties of Heat Exchanger and Steam Generator Alloys

International Nuclear Information System (INIS)

Wright, J.K.; Carroll, L.J.; Benz, J.K.; Simpson, J.A.; Wright, R.N.; Lloyd, W.R.; Chapman, J.A.

2010-01-01

The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. In general dynamic strain aging is observed to begin at higher temperatures and serrated flow persists to higher temperatures in Alloy 617 compared to Alloy 800H. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. The role of dynamic strain aging in the creep-fatigue behavior of Alloy 617 at temperatures of 800 C and above has also been examined in detail. Serrated flow is found to persist in cyclic stress-strain curves up to nearly the cycle to failure in some temperature and strain regimes. Results of those experiments and implications for creep-fatigue testing protocols will be described.

Tensile properties of Zr-2.5 Nb pressure tube alloy between 25 and 800 degC

International Nuclear Information System (INIS)

Singh, R.N.; Kishore, R.; Sinha, T.K.; Banerjee, S.

2000-10-01

Tensile properties of zirconium-2.5 wt. % niobium pressure tube material were evaluated by uniaxial tension tests at temperatures between 25 and 800 degC and under strain-rates varying from 3.3 x 10 -5 to 3.3 x 10 -3 /s. Tests were carried out on specimens fabricated from the sections of finished (autoclaved) tubes as well as on those machined from the sections of cold worked (2 nd pilgered) tubes. Moreover, specimens fabricated from finished tubes belonging to twenty different heats were tested at 300 degC to study the heat to heat variation in tensile properties of this alloy. In order to study the effect of the crystallographic texture on the tensile properties, specimens oriented in longitudinal as well as, in transverse directions of the tubes were also tested. Results showed that both yield and ultimate tensile strengths of this alloy decreased monotonically with increasing test temperatures, with a rapid fall in strengths above a temperature of 350 degC (623 K). The tensile ductility did not change appreciably up to 400 degC (673K) but increased rapidly above this temperature. The observed results on the temperature dependence of the strength and ductility indicated the possible occurrence of dynamic strain-ageing in this alloy in the temperature range of 200-300 degC (473 to 573 K). The transverse specimens showed higher strengths and lower ductility as compared to those of the longitudinal specimens up to a temperature of 350 degC (623 K). Above 350 degC, the difference in the strengths and the ductility of the two types of the specimens, became negligibly small indicating that the texture did not appreciably influence the tensile properties of this alloy at temperatures exceeding 350 degC. The alloy developed extensive superplasticity (ductility exceeding 100 %), when tested in the temperature range of 650-800 degC. Maximum ductility values of 650 % for longitudinal and 900 % for the transverse orientation with strain-rate sensitivity (m) exceeding 0

Characterization of elevated temperature properties of heat exchanger and steam generator alloys

International Nuclear Information System (INIS)

Wright, J.K.; Carroll, L.J.; Cabet, C.; Lillo, T.M.; Benz, J.K.; Simpson, J.A.; Lloyd, W.R.; Chapman, J.A.; Wright, R.N.

2012-01-01

The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 °C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 °C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 °C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. High temperature tensile testing of Alloy 617 and Alloy 800H has been conducted over a range of temperatures. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. Creep, fatigue, and creep–fatigue properties of Alloy 617 have been measured as well, with the goal of determining the influence of the temperature, strain rate and atmosphere on the creep–fatigue life of Alloy 617. Elevated temperature properties and implications for codification of the alloys will be described.

Corrosion resistance of materials of construction for high temperature sulfuric acid service in thermochemical IS process. Alloy 800, Alloy 600, SUSXM15J1 and SiC

International Nuclear Information System (INIS)

Tanaka, Nobuyuki; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa

2006-01-01

Exposure tests of candidate materials were carried out up to 1000 hr in the sulfuric acid environments of thermochemical hydrogen production IS process, focusing on the corrosion of welded portion and of crevice area. In the gas phase sulfuric acid decomposition condition at 850degC, welded samples of Alloy 800 and of Alloy 600 showed the same good corrosion resistance as the base materials. In the boiling condition of 95 wt% sulfuric acid solution, test sample of SiC showed the same good corrosion resistance. Also negligible corrosion was observed in crevice corrosion. (author)

Alloy 800 - A review of properties and metallurgy

International Nuclear Information System (INIS)

Stone, P.G.; Orr, J.

1976-01-01

It is shown that the properties and metallurgy of alloy 800 are significantly influenced by relatively small changes in composition introduced by the nuclear industry in order to obtain better stress corrosion resistance. Two particular metallurgical effects are considered: the influence of lower TiC volume fraction on grain coarsening behavior and grain size; the influence of increased amounts of titanium in solid solution on Ni 3 (AlTi) precipitation. The first effect has a direct influence on proof stress properties, and the second on stress rupture strength and ductility. However, the important effect of aluminium on this behavior is emphasized. Other aspects considered are the effect of long reheating times during operation on proof strength and impact resistance. The final part of the paper deals with two fabrication aspects. After demonstrating the detrimental effect of cold working on stress rupture ductility, the susceptibility to premature failure is examined, using notched stress rupture specimens. Although notch sensitivity was found in short term tests, additional work suggests that it may not occur after longer testing times. The effect of stress relieving on this behavior is reported. The welding aspects considered include the compositional factors influencing liquation cracking, grain growth during welding, and the proof strength and stress rupture properties of welded material

Compression of Fe-Si-H alloys

Science.gov (United States)

Tagawa, S.; Ohta, K.; Hirose, K.

2014-12-01

The light elements in the Earth's core have not been fully identified yet, but hydrogen is now collecting more attention in part because recent planet formation theory suggests that large amount of water should have been brought to the Earth during its formation (giant-impact stage). Nevertheless, the effect of hydrogen on the property of iron alloys is little known so far. The earlier experimental study by Hirao et al. [2004 GRL] examined the compression behavior of dhcp FeHx (x ≈ 1) and found that it becomes much stiffer than pure iron above 50 GPa, where magnetization disappears. Here we examined the solubility of hydrogen into iron-rich Fe-Si alloys and the compression behavior of dhcp Fe-Si-H alloy at room temperature. Fe+6.5wt.%Si or Fe+9wt.%Si foil was loaded into a diamond-anvil cell (DAC), and then liquid hydrogen was introduced at temperatures below 20 K. X-ray diffraction measurements at SPring-8 revealed the formation of a dhcp phase with or without thermal annealing by laser above 8.4 GPa. The concentration of hydrogen in such dhcp lattice was calculated following the formula reported by Fukai [1992]; y = 0.5 and 0.2 for Fe-6.5wt.%Si-H or Fe-9wt.%Si-H alloys, respectively when y is defined as Fe(1-x)SixHy. Unlike Fe-H alloy, hydrogen didn't fully occupy the octahedral sites even under hydrogen-saturated conditions in the case of Fe-Si-H system. Anomaly was observed in obtained pressure-volume curve around 44 Å3 of unit-cell volume for both Fe-6.5wt.%Si-H and Fe-9wt.%Si-H alloys, which may be related to the spin transition in the dhcp phase. They became slightly stiffer at higher pressures, but their compressibility was still similar to that of pure iron.

Sulfidation behavior of Fe20Cr alloys

International Nuclear Information System (INIS)

Pillis, Marina Fuser

2001-01-01

Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

Comparative study of oxalic and malonic acid behaviour in the chemical cleaning of alloy 800 surfaces

International Nuclear Information System (INIS)

Garcia, Damian A.; Bruyere, Vivienne I.E.; Bordoni, Roberto A.; Olmedo, Ana M.; Morando, Pedro J.

2004-01-01

This work consisted, in a first stage, on a basic study of the dissolution mechanism of nickel ferrite in aqueous malonic acid. Powdered oxides (Ni x Fe 3-x O 4 ) were synthesized by wet procedures and heated at 750 C degrees. These oxides were characterized by conventional methods and dissolved under different experimental conditions (pH, reagent concentration, temperature, etc.) in order to determine the dissolution rates. Optimal dissolution conditions were explored and compared to the corresponding oxalic acid ones. In a second stage, these conditions were applied to oxides grown on Alloy 800 coupons. Before oxidation, all coupons were ground polished and then were exposed to hydrothermal conditions (350 C degrees, pH 25Cdegrees ≅ 10.4 -LiOH-, 20-22 days) in static autoclaves. Finally, oxidized and unoxidized coupons were treated with chemical solutions containing oxalic or malonic acid at conditions optimized in the first stage. These results were also compared to those obtained on coupons exposed to a commercial formulation, APAC (Alkaline Permanganate Ammonium Citrate), as a reference. The results on coupon descaling using APMAL (AP + Malonic), APOX (AP + oxalic) and the comparison with APAC leads to conclude that malonic acid is a reagent whose chemical behavior is much better than oxalic acid and comparable to commercial formulations. (author) [es

Effect of chloride and sulphate ions on the electrochemical corrosion behavior of alloy 800NG in PWR secondary water environment at 250 deg C

International Nuclear Information System (INIS)

Mansur, Fabio A.; Schvartzman, Monica Maria de A.M.; Quinan, Marco A.D.; Soares, Antonio E.G.; Nogueira, Pedro Henrique B.O.

2013-01-01

Alloy 800NG (nuclear grade) is used in nuclear steam generators (SG) as the tubing material for pressurized water reactors (PWRs) because of its high corrosion resistance. The corrosion resistance is due to the protective character of the oxide film formed on the tube surface by contact with the high temperature pressurized water. Nevertheless, corrosion has been the major cause of tube failures in nuclear SGs. The existing experience of different nuclear power plants shows that the water chemistry has an important role in maintaining the integrity of the protective oxide films. Many of such problems have been attributed to secondary side water chemistry conditions and excursions, many of which have been resulted from condenser cooling water ingress. Alloy 800 is known to undergo passivity breakdown and pitting in the presence of chloride ions under oxidative water conditions. In this work the effect of chloride and sulphate ions at various concentrations on the corrosion behavior of Alloy 800 tube at 250 deg C was investigated using the potentiodynamic anodic polarization technique. An active-passive transition occurred at 250 deg C in all studied conditions and the oxide film grown on surface showed greater porosity and lower resistance to localised corrosion in all studied conditions. (author)

High-Temperature Tensile Strength of Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy (High-Entropy Alloy)

Science.gov (United States)

Daoud, H. M.; Manzoni, A. M.; Wanderka, N.; Glatzel, U.

2015-06-01

Homogenizing at 1220°C for 20 h and subsequent aging at 900°C for 5 h and 50 h of a novel Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy (high-entropy alloy) produces a microstructure consisting of an L12 ordered γ' phase embedded in a face-centered cubic solid-solution γ matrix together with needle-like B2 precipitates (NiAl). The volume fraction of γ' phase is ~46% and of needle-like B2 precipitates database; Thermo-Calc Software, Stockholm, Sweden). The high-temperature tensile tests were carried out at room temperature, 600°C, 700°C, 800°C, and 1000°C. The tensile strength as well as the elongation to failure of both heat-treated specimens is very high at all tested temperatures. The values of tensile strength has been compared with literature data of well-known Alloy 800H and Inconel 617, and is discussed in terms of the observed microstructure.

The influence of prior ageing on microstructure, tensile properties and hot hardness of alloy 800HT

International Nuclear Information System (INIS)

El-Magd, E.

1996-01-01

For high temperature applications especially in the construction of equipment, carbide strengthened steels are widely used because of their good mechanical properties and relatively low cost. These materials undergo microstructural changes under such service conditions which contribute greatly to the strength properties and thus play an important role in equipment design considerations. The influence of a prior thermal ageing on the tensile strength values and the hot hardness of the austenitic iron base alloy, Alloy 800HT, is examined in this work. It was therefore necessary to carry out tensile and hot hardness tests with the solution treated and overaged material at ranges between room temperature and 900 . The microstructural changes are investigated using lightmicroscopy, SEM and TEM. The changes of the material properties with thermal pretreatment conditions is studied and discussed in the context of the determined microstructural development. (orig.) [de

Examination of steam generator alloy 800 NG tube from the Almaraz unit 2 NPP

International Nuclear Information System (INIS)

Diego, G. de; Gomez Briceno, D.; Maffiotte, C.; Baladia, M.; Arias, C.J.

2015-01-01

The steam generators of Almaraz Unit 2 were replaced in 1997 by the model 61W/D3 (Siemens) with Alloy 800NG steam generator tubes. Denting indications were firstly detected in 2006 in the SG-3. Crack indications were identified in 2009. At the end of 2011, three tubes were recovered from this steam generator to carry out destructive examination in order to identify the root cause of the tubes degradation. Analysis of deposits point out the existence of multiples elements in the removed OD (Outer Diameter) deposits as well as in the deposits at the free tube under sludge and at the transition zone. Deposits are more abundant at the transition zone than at free tube. About 10% Na concentration has been detected, whereas S and Cl appear in small concentrations. Si appears regularly and Cr, Ni concentrations in the deposits are similar. Multiple intergranular cracks have been detected at 3 mm above the last contact point between the tube and the TS (tube support), in a band of around 5 mm, practically in the whole perimeter of the tube. Fracture surface of crack-B was partially covered by a Si rich layer, whereas fracture surface of crack-A seems to be cleaner. However, no significant differences in composition, except higher amount of S in crack-B, were found in the deposits of both cracks. EDX mapping and Auger profiles point out Ni enrichment with slight Cr enrichment or depletion and Fe depletion. The comparison of Auger profiles with available results for Alloy 800 tested in caustic and acid sulfate environments seems to indicate that the environment inside the cracks detected in the tube R67C48 is neutral or moderately caustic

Solute partitioning and interfacial segregation in TiAl-based alloys

International Nuclear Information System (INIS)

Larson, D.J.; Miller, M.K.

1999-01-01

Atom probe microscopy has been used to investigate elemental partitioning and segregation behavior in a TiAl-based alloy with a variety of alloying additions including Cr, Nb, W and B. These results indicate that in a stress-relieved state (2h at 900 C) and a reheated state (2h at 900 C, 2,184h at 800 C and 2h at 1,210 C) chromium, and to a lesser extent tungsten, is partitioned to the α 2 phase. However, in an annealed state (2h at 900 C and 720 h at 800 C), these elements are partitioned to the γ phase. Segregation of chromium and tungsten to lamellar interfaces is observed in the stress-relieved material, but significant segregation was not observed in material subjected to the other heat treatments. A W- and B-enriched precipitate was observed in the reheated material and provides a possible explanation for the low tungsten concentrations measured in the matrix phases

Assessment of the Polyacrylic Acid for an Ammonia Water Treatment and for Alloy 800NG SG Tube Material in Pressurized Water Reactors

International Nuclear Information System (INIS)

Lamouroux, Christine; You, Dominique; Plancque, Gabriel; Roy, Marc; Laire, Charles; Schnongs, Philippe

2012-09-01

To prevent the Steam Generators (SG) fouling by corrosion products or the Tube Support Plate (TSP) blockage the on-line injection of a dispersant such the Polyacrylic Acid (PAA) could be a relevant water treatment. Long-term trials performed in PWRs have shown that the PAA, injected at the SG inlet, facilitate the evacuation of the iron oxides by the SG blowdown. Given the ammonia treatment of the secondary water of the Belgian PWRs, the R and D program carried out was devoted to: - Verify the innocuousness of the PAA and its degradation products versus Alloy 800NG SCC susceptibility in case of over concentrations and sludge presence, - Assess the potential impact of the PAA and its thermal degradation products on the specific NH 3 water treatment. The main results can be summarized as following: The corrosion tests performed with PAA in case of over concentrations and sludge couldn't point out any negative effect of the dispersant on the SCC susceptibility of tubing materials such as Alloy 800NG. No significant modification of the tube oxide layer has been observed. At the SG operating temperature, the PAA is decomposed and a large spectrum from high to lower molecular weights polymers than the initial PAA arises. The fragmentation of the polymer into low molecular weight polyacrylic acids is obtained within 20 minutes and the average molecular weight is reduced by 50% from the original one. The thermal degradation products, their quantity and their kinetic of appearance, have been determined. The generated acetate concentration during the on-line dispersant application should remain low compared to the current values observed in the SG water. From the numerical simulation based on acetate concentration and on the kinetic law deduced from the experimental work, it can be concluded that in a 2-phase medium, the margin on the water pH compared to the neutral pH remains high. At 180 deg. C, no impact on the water pH is identified, taking into account realistic

Microstructural characterization of dissimilar welds between Incoloy 800H and 321 Austenitic Stainless Steel

Energy Technology Data Exchange (ETDEWEB)

Sayiram, G., E-mail: sayiram.g@vit.ac.in; Arivazhagan, N.

2015-04-15

In this work, the microstructural character of dissimilar welds between Incoloy 800H and 321 Stainless Steel has been discussed. The microscopic examination of the base metals, fusion zones and interfaces was characterized using an optical microscope and scanning electron microscopy. The results revealed precipitates of Ti (C, N) in the austenitic matrix along the grain boundaries of the base metals. Migration of grain boundaries in the Inconel 82 weld metal was very extensive when compared to Inconel 617 weldment. Epitaxial growth was observed in the 617 weldment which increases the strength and ductility of the weld metal. Unmixed zone near the fusion line between 321 Stainless Steel and Inconel 82 weld metal was identified. From the results, it has been concluded that Inconel 617 filler metal is a preferable choice for the joint between Incoloy 800H and 321 Stainless Steel. - Highlights: • Failure mechanisms produced by dissimilar welding of Incoloy 800H to AISI 321SS • Influence of filler wire on microstructure properties • Contemplative comparisons of metallurgical aspects of these weldments • Microstructure and chemical studies including metallography, SEM–EDS • EDS-line scan study at interface.

Study of the polarization for Incoloy 800 and for the stainless stell AISI 304 in mixtures of Iron, Nickel and Chromium Chlorides

International Nuclear Information System (INIS)

Travalloni, A.M.; Sathler, L.; Mattos, O.R.

1985-01-01

Polarization curves for the Incoloy 800 and for the stainless stell AISI 304 were obtained with static and rotational electrodes. The electrolytes employed showed growing concentrations of mixtures as Iron, Nickel and Chromium Chlorides their proportion being the same as the content of these elements in the respective alloys. The alloys under investigation exhibited a continuous transition behaviour from the passive to the active-passive and to the active conditions. Also, the pH was found the main parameter controlling the anodic behaviour of the alloy. (Author) [pt

Modeling interactive effects of Pb contamination, Ca"2"+ and Mg"2"+ on passivity of alloy 800 in simulated crevice chemistries at high temperature

International Nuclear Information System (INIS)

Lu, Baotong

2015-01-01

Highlights: • The capability of Pb impurity degrading the passivity of alloy 800 in high temperature water is much stronger than those of dissolved Ca/Mg salts. • The interactive effects of Pb-impurities and Ca/Mg salts on the passivity are likely a result competitive adsorption. • A phenomenological model to interpret the interactive effect of Pb-impurities and Ca/Mg salts on the passivity. - Abstract: A phenomenological model is postulated to interpret the interactive impacts of dissolved Pb contamination, Ca"2"+ and Mg"2"+ on passivity of Alloy 800 in simulated crevice chemistries at 300 °C. Passivity degradation is characterized by the retarded dehydration during passivation and increased donor density in passive film. Ca"2"+ and Mg"2"+ can cause the passivity degradation in the Pb-free chemistries but, if the Pb-contamination concentration exceeds a critical value, would reduce the detrimental effect of Pb-contamination. This behavior may be related to the extremely strong adsorption capacity of Pb contamination. Finally, the applications in the water management strategy of nuclear power plants are discussed.

Novel Dissimilar Joints Between Alloy 800H and 2.25%Cr and 1%Mo Steel

Energy Technology Data Exchange (ETDEWEB)

DebRoy, Tarasankar

2017-12-31

Dissimilar metal joints between ferritic steels and nickel base alloys are currently fabricated using conventional arc welding processes with selected filler metal combinations. The dissimilar metal joints contain abrupt changes in composition over a relatively small distance. Many years of service at elevated temperatures has shown that these welds are susceptible to creep and creep fatigue failures. The primary mechanism for these creep failures involves carbon diffusion from the ferritic steel to the nickel base alloy. As a result, a carbon depleted zone is created that contains very few stable carbides. This work used additive manufacturing (AM) technologies as a highly controllable means for reducing carbon migration through theoretically designed, compositionally graded transition joints guided by appropriate thermodynamic, kinetic and heat transfer and fluid flow modeling. The contents of the report include the objectives and tasks set forth by the PI and collaborators, major technical accomplishments throughout the research and additional details in the form of technical publications resulting from the NEUP grant and reports from the collaborating university and national laboratory.

Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

Directory of Open Access Journals (Sweden)

Rajković Višeslava

2004-01-01

Full Text Available The copper matrix has been dispersion strengthened with 3wt.%Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.75mm was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H2 at 4000C for 1h, and finally hot pressing was used for compaction (800oC, 3h, Ar. Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa compacted under identical conditions, while after 20h of milling it was 2370 MPa. However after exposing the tested compact at 800oC up to 5h, the achieved hardening effect vanished.

Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

Directory of Open Access Journals (Sweden)

Pillis Marina Fuser

2004-01-01

Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

High-temperature corrosion and mechanical properties of protective scales on Incoloy 800H: The influence of preoxidation and ion implantation

NARCIS (Netherlands)

Polman, E.A.; Fransen, T.; Gellings, P.J.

1990-01-01

Coatings, obtained by preoxidation of Incoloy 800H at low PO2 show good sulphidation resistance due to the higher chromia content in the oxide scale. Yttrium-ion implantation of Incoloy 800H has also a beneficial effect on sulphidation, if preoxidation is applied. The reason for this is presumably

2nd Gen FeCrAl ODS Alloy Development For Accident-Tolerant Fuel Cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Massey, Caleb P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Edmondson, Philip D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

Extensive research at ORNL aims at developing advanced low-Cr high strength FeCrAl alloys for accident tolerant fuel cladding. One task focuses on the fabrication of new low Cr oxide dispersion strengthened (ODS) FeCrAl alloys. The first Fe-12Cr-5Al+Y₂O₃ (+ ZrO₂ or TiO₂) ODS alloys exhibited excellent tensile strength up to 800 C and good oxidation resistance in steam up to 1400 C, but very limited plastic deformation at temperature ranging from room to 800 C. To improve alloy ductility, several fabrication parameters were considered. New Fe-10-12Cr-6Al gas-atomized powders containing 0.15 to 0.5wt% Zr were procured and ball milled for 10h, 20h or 40h with Y2O3. The resulting powder was then extruded at temperature ranging from 900 to 1050 C. Decreasing the ball milling time or increasing the extrusion temperature changed the alloy grain size leading to lower strength but enhanced ductility. Small variations of the Cr, Zr, O and N content did not seem to significantly impact the alloy tensile properties, and, overall, the 2nd gen ODS FeCrAl alloys showed significantly better ductility than the 1st gen alloys. Tube fabrication needed for fuel cladding will require cold or warm working associated with softening heat treatments, work was therefore initiated to assess the effect of these fabrications steps on the alloy microstructure and properties. This report has been submitted as fulfillment of milestone M3FT 16OR020202091 titled, Report on 2nd Gen FeCrAl ODS Alloy Development for the Department of Energy Office of Nuclear Energy, Advanced Fuel Campaign of the Fuel Cycle R&D program.

Corrosion of zirconium alloys in alternating pH environment

International Nuclear Information System (INIS)

Mayer, P.; Manolescu, A.V.

1985-01-01

Behaviour of two commercial alloys, Zircaloy-2 and zirconium-2.5 wt% niobium were investigated in an environment of alternating pH. Corrosion advancement and scale morphology of coupons exposed to aqueous solution of LiOH (pH 10.2 and 14) were followed as a function of temperature (300-360 degreesC) and time (up to 165 days). The test sequence consisted of short term exposure to high pH and re-exposure to low pH solutions for extended period of time followed by a short term test in high pH. The results of these tests and detailed post-corrosion analysis indicate a fundamental difference between the corrosion behaviour of these two materials. Both alloys corrode fast in high pH environments, but only zirconium-2.5 wt% niobium continues to form detectable new oxide in low pH solution

Residual stresses determination in an 8 mm Incoloy 800H weld via neutron diffraction

International Nuclear Information System (INIS)

Chen, Xizhang; Zhang, Shu Yan; Wang, Jingjun; Kelleher, Joe F.

2015-01-01

Highlights: • Stress through thickness at 5 mm from weld centerline indicates a “U” distribution. • Declining of tensile stress through thickness occurred at weld centerline. • Residual stress between layers is the lowest. - Abstract: To investigate the distribution of residual stresses, the 8 mm 800H alloy was joined by multi-layer butt TIG process. Residual stresses in the longitudinal, transverse and normal directions were measured via neutron diffraction. These residual stress measurements were taken at a series of points 2 mm below the top surface, covering the fusion zone, heat affected zone (HAZ) and base metal. In addition, two lines of longitudinal residual stress values at the weld centerline and 5 mm from weld centerline through thickness were measured. Results show that both the longitudinal and transverse stresses from the weld centerline to base metal are mainly tensile stresses. The longitudinal residual stress is the largest, with a maximum value of 330 MPa. As for the normal residual stress, the weld zone shows tensile stress, while the HAZ shows compressive stress. The middle of the thickness shows compressive residual stress along the thickness direction. The longitudinal stress at weld centerline through thickness reveals the interlayer heat treat effects leads to a declining of tensile stress. While the stress at 5 mm from weld centerline indicates a “U” distribution due to the mixed microstructure close to fusion line. With the increasing distance from weld seam, the residual stress decreases gradually

Total photoabsorption cross sections for {sup 1}H, {sup 2}H and {sup 3}He from 200 to 800 MeV

Energy Technology Data Exchange (ETDEWEB)

Mac Cormick, M.; Audit, G. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Altieri, S.; Braghieri, A. [Istituto Nazionale di Fisica Nucleare, Pavia (Italy)]|[Pavia Univ. (Italy). Ist. di Fisica Nucleare; Ahrens, J.; Beck, R. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Annand, J.R.M.; Crawford, R.A. [Glasgow Univ. (United Kingdom). Dept. of Physics and Astronomy; Dolbilkin, B.; Zabrodin, A. [AN SSSR, Moscow (Russian Federation). Inst. Yadernykh Issledovanij] [and others

1996-01-01

The total photoabsorption cross sections for {sup 1}H, {sup 2}H and {sup 3}He have been measured for incident photon energies ranging from 200 to 800 MeV. The results show clearly the changes in the nucleon resonances in going from {sup 1}H to {sup 3}He. In particular, for the D{sub 13} region the behaviour for {sup 3}He is intermediate between that for {sup 1}H, {sup 2}H and heavier nuclei. (author). Submitted to Physical Review, C (US); 26 refs.

Stress Corrosion Cracking of Ni-Fe-Cr Alloys Relevant to Nuclear Power Plants

Science.gov (United States)

Persaud, Suraj

Stress corrosion cracking (SCC) of Ni-Fe-Cr alloys and weld metals was investigated in simulated environments representative of high temperature water used in the primary and secondary circuits of nuclear power plants. The mechanism of primary water SCC (PWSCC) was studied in Alloys 600, 690, 800 and Alloy 82 dissimilar metal welds using the internal oxidation model as a guide. Initial experiments were carried out in a 480°C hydrogenated steam environment considered to simulate high temperature reducing primary water. Ni alloys underwent classical internal oxidation intragranularly resulting in the expulsion of the solvent metal, Ni, to the surface. Selective intergranular oxidation of Cr in Alloy 600 resulted in embrittlement, while other alloys were resistant owing to their increased Cr contents. Atom probe tomography was used to determine the short-circuit diffusion path used for Ni expulsion at a sub-nanometer scale, which was concluded to be oxide-metal interfaces. Further exposures of Alloys 600 and 800 were done in 315°C simulated primary water and intergranular oxidation tendency was comparable to 480°C hydrogenated steam. Secondary side work involved SCC experiments and electrochemical measurements, which were done at 315°C in acid sulfate solutions. Alloy 800 C-rings were found to undergo acid sulfate SCC (AcSCC) to a depth of up to 300 microm in 0.55 M sulfate solution at pH 4.3. A focused-ion beam was used to extract a crack tip from a C-ring and high resolution analytical electron microscopy revealed a duplex oxide structure and the presence of sulfur. Electrochemical measurements were taken on Ni alloys to complement crack tip analysis; sulfate was concluded to be the aggressive anion in mixed sulfate and chloride systems. Results from electrochemical measurements and crack tip analysis suggested a slip dissolution-type mechanism to explain AcSCC in Ni alloys.

SEM-EDS and XRD study of a NiCrAlU alloy at temperatures from 800 celsius degree to 1300 celsius degree

International Nuclear Information System (INIS)

Al-Badairy, H.; Fox, P.

2004-01-01

Full text.The oxidation behaviour of a 74.5wt%Ni, 20wt%Cr, 5wt%Al and 0.5wt%U alloy was examined using Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy (SEM-EDS) and X-ray Diffractometry (XRD). The oxidation temperature ranged from 800 to 1300 celsius degree in laboratory air with oxidation times up to 120h. Analysis showed that during short term oxidation (40h) at the lower temperatures there was evidence of the formation of Cr, Ni and Al oxides. With increasing oxidation time, the Cr-rich oxide became predominant with the presence of islands of Ni-rich oxide, but no uranium was detected at the outermost layer of the scale. The scale was of flat topography with spallation occurring after 40h oxidation at 900 celsius degree and increasing with increasing temperature and time. Cross-sectional investigations indicated the presence of an internal oxidation zone comprising an Al-rich oxide beneath the outer Cr-rich scale with significant amounts of uranium. The depth of this zone varied from 1 micron to 60 microns and increased with increasing the oxidation temperature and time. At higher temperatures (above 1000 celsius degree), the internal oxidation zone ceased to grow due to the formation of a complete layer of alumina which protected the metal substrate from further degradation. The constituents of the scales formed reflect the selective oxidation of Cr and Al as a result of the higher reactivity of aluminium and chromium compared to nickel and the greater stability of Al 2 O 3 and Cr 2 O 3 compared to NiO. This study showed that Al-rich oxide was not the predominant protective oxide and the presence of uranium was restricted to the grain boundaries of the metal substrate and to within the internal oxidation zone. It appeared that the Cr-rich scale formed on this alloy does not to convolute. This may be due to the influence of uranium since Cr-rich scales forming on NiCrAl containing no uranium are often convoluted

Mechanisms Governing the Creep Behavior of High Temperature Alloys for Generation IV Nuclear Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Vasudevan, Vijay [Univ. of Cincinnati, OH (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sham, Sam [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-04-06

This research project, which includes collaborators from INL and ORNL, focuses on the study of alloy 617 and alloy 800H that are candidates for applications as intermediate heat exchangers in GEN IV nuclear reactors, with an emphasis on the effects of grain size, grain boundaries and second phases on the creep properties; the mechanisms of dislocation creep, diffusional creep and cavitation; the onset of tertiary creep; and theoretical modeling for long-term predictions of materials behavior and for high temperature alloy design.

Mechanisms Governing the Creep Behavior of High Temperature Alloys for Generation IV Nuclear Energy Systems

International Nuclear Information System (INIS)

Vasudevan, Vijay; Carroll, Laura; Sham, Sam

2015-01-01

This research project, which includes collaborators from INL and ORNL, focuses on the study of alloy 617 and alloy 800H that are candidates for applications as intermediate heat exchangers in GEN IV nuclear reactors, with an emphasis on the effects of grain size, grain boundaries and second phases on the creep properties; the mechanisms of dislocation creep, diffusional creep and cavitation; the onset of tertiary creep; and theoretical modeling for long-term predictions of materials behavior and for high temperature alloy design.

Recent progresses in the understanding of the elastic and anelastic properties of H-free, H-doped and H-contaminated NiTi based alloys

Directory of Open Access Journals (Sweden)

Giovanni Mazzolai

2011-12-01

Full Text Available This review is focused on the influence of interstitial hydrogen and alloy compositional changes on the internal friction (IF spectrum and elastic Young's modulus (E of NiTi based shape memory alloys. In the martensitically transforming binary alloys Ni50+xTi50-x (x≤1.3 vacuum annealed and furnace cooled (H-free, besides the well known IF peak associated with the martensitic transition two additional non-thermally activated peaks (P150K and P200K′ are present due to some sort of second-order phase transitions. In martensitically transforming Ni50+xTi50-x and Ti50Ni50-yCuy alloys doped with hydrogen two thermally activated peaks, PTWH and PH, appear which originate from stress-assisted motions of H-twin boundary complexes and isolated H-elastic dipoles (Snoek effect, respectively. In a H-free martensitically non-trasforming alloy (x=2, besides the non-thermally activated peak P150K, a frequency dependent dip is observed in the E(T curves at a temperature Tg. This dip is similar to that reported in the literature for two other non-transforming alloys (x=1.5 and x=2.5, which, however, were also found to exhibit a thermally activated IF peak just below Tg. Most likely, these two alloys were contaminated with hydrogen during the preliminary solubilization in argon atmosphere and subsequent water quenching treatments given to them. The Young's modulus dip and the lower temperature IF peak have been both attributed to a novel type of phase transition reported in the literature as “strain glass transition”. The introduction of hydrogen into the non-transforming alloy with x=2 enhances the Young's modulus dip and gives rise to the H-Snoek peak PH just below Tg, which clearly appears to be the counterpart of the peak observed in the alloys (x=1.5 and x=2.5 solubilized in argon atmosphere and water quenched. The conclusion was reached in the present work that this last peak is not related to the strain glass transition but is rather an H

Penentuan konsentrasi stainless steel 316L dan kobalt kromium remanium GM-800 pada uji GPMT

Directory of Open Access Journals (Sweden)

Ikmal Hafizi

2016-12-01

Full Text Available Concentration determination of stainless steel 316L and cobalt chromium remanium GM - 800 on GPMT test. Dentistry had used metals such as cobalt chromium and stainless steel in maxillofacial surgery, cardiovascular, and as a dental material. 316L stainless steel is austenistic stainless steel which has low carbon composition to improve the corrosion resistance as well as the content of molybdenum in the material. Cobalt chromium (CoCr is a cobaltbased alloy with a mixture of chromium. Density of a metal cobalt chromium alloy is about 8-9 g/cm3 that caused metal interference relatively mild. Remanium GM-800 is one type of a cobalt chromium alloy with the advantages of having high resistance to fracture and high modulus of elasticity. This study aims to determine the exact concentration used in 316L stainless steel and cobalt chromium GM-800 as the GPMT test material. Subjects were cobalt chromium Remanium GM-800 and 316L stainless steel concentration of 5%, 10%, 20%, 40% and 80%. Patch containing stainless steel or cobalt chromium paste was af xed for 24 hours each on three experimental animals, then the erythema and edema were observed using the Magnusson and Kligman scale. In the study, concentration of 5% is the concentration recommended for stainless steel 316L and cobalt chromium GM-800 as material in challenge phase GPMT test, while the concentration of 40% is the concentration recommended for stainless steel 316L and cobalt chromium GM-800 in the induction phase. ABSTRAK Dunia kedokteran gigi banyak menggunakan logam pada pembedahan maxillofacial, cardiovascular, dan sebagai material dental. Logam yang banyak digunakan antara lain adalah kobalt kromium dan stainless steel. Stainless steel 316L merupakan austenistic stainless steel yang memiliki komposisi karbon rendah sehingga dapat meningkatkan ketahanan terhadap korosi sama halnya dengan kandungan molybdenum pada material tersebut. Kobalt kromium (CoCr adalah cobalt-based alloy dengan

Artificial neural network modeling studies to predict the friction welding process parameters of Incoloy 800H joints

Directory of Open Access Journals (Sweden)

K. Anand

2015-09-01

Full Text Available The present study focuses on friction welding process parameter optimization using a hybrid technique of ANN and different optimization algorithms. This optimization techniques are not only for the effective process modelling, but also to illustrate the correlation between the input and output responses of the friction welding of Incoloy 800H. In addition the focus is also to obtain optimal strength and hardness of joints with minimum burn off length. ANN based approaches could model this welding process of INCOLOY 800H in both forward and reverse directions efficiently, which are required for the automation of the same. Five different training algorithms were used to train ANN for both forward and reverse mapping and ANN tuned force approach was used for optimization. The paper makes a robust comparison of the performances of the five algorithms employing standard statistical indices. The results showed that GANN with 4-9-3 for forward and 4-7-3 for reverse mapping arrangement could outperform the other four approaches in most of the cases but not in all. Experiments on tensile strength (TS, microhardness (H and burn off length (BOL of the joints were performed with optimised parameter. It is concluded that this ANN model with genetic algorithm may provide good ability to predict the friction welding process parameters to weld Incoloy 800H.

Corrosion of alloy 800 in PHWR primary and secondary conditions

International Nuclear Information System (INIS)

Maroto, A.J.G.; Blesa, M.A.; Villegas, M.; Olmedo, A.M.; Bordoni, R.; Alvarez, M.G.; Sainz, R.

1998-01-01

A hot leg section of a steam generator tubing was removed for destructive examination from one of the steam generators (SG) of the Embalse Nuclear Power Plant. The tube material is Alloy 800 and carbon steel is the tube support plate material. Samples of the deposits were taken at the first tube support plate and at the top, mid-height and bottom of the sludge pile. Transverse sections were taken at several locations along the tube length measuring the oxide thicknesses and studying the morphology of the oxide layer by scanning electron microscopy on the primary and secondary side at each location. Deposit layers on the outer tube surface revealed iron as major component and the presence of calcium, phosphorous, zinc and manganese. The oxide scale thickness at the secondary side in the open area was around 22 to 30 μm. The oxide thickness grown under isothermal conditions on the corrosion test samples installed in the autoclaves facilities of the primary circuit of the plant was measured and compared with that found on the inner surface of the examined tube section. The oxide thickness of the test samples was around 1-2 μm showing the influence of the deposition of corrosion products from the coolant. Deposition and precipitation of oxide was also found in the actual tube, where the common feature was the irregularity of the oxide layer on the primary side and thicknesses values in the range 4 to 10 μm were measured. The autoclave tests and SG tubing examination permit to compare the influence of materials and of operating (flow rate, isothermal vs non-isothermal) conditions on corrosion and deposition. (author)

Structural evolution of Cu{sub (1−X)}Y{sub X} alloys prepared by mechanical alloying: Their thermal stability and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Mula, Suhrit, E-mail: smulafmt@iitr.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Setman, Daria [Physics of Nanostructured Materials, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Youssef, Khaled [Department of Materials Science and Technology, Qatar University, P.O. Box 2713, Doha (Qatar); Scattergood, R.O.; Koch, Carl C [Department of Materials Science and Engineering, NC State University, Raleigh, NC 27695 (United States)

2015-04-05

Highlights: • Metastable solid solutions were prepared from Cu–Y nonequilibrium compositions by mechanical alloying. • Gibbs free energy change as per Miedema’s model confirms the formation of metastable alloys. • High Y content alloys showed high thermal stability during extensive annealing at high temperatures. • Stabilized alloys showed very high hardness and improved yield strength. • Mechanisms of high thermal stability and improved mechanical properties were discussed. - Abstract: In the present study, an attempt has been made to synthesize copper based disordered solid solutions by mechanical alloying (MA) of non-equilibrium compositions. The blended compositions of Cu–1% Y, Cu–3% Y, Cu–5% Y and Cu–7.5% Y (at.%) (all the compositions will be addressed as % only hereafter until unless it is mentioned) were ball-milled for 8 h, and then annealed at different temperatures (200–800 °C) for different length of duration (1–5 h) under high purity argon + 2 vol.% H{sub 2} atmosphere. X-ray diffraction (XRD) analysis and Gibbs free energy change calculation confirm the formation of disordered solid solution (up to 7.5%) of Y in Cu after milling at a room temperature for 8 h. The XRD grain size was calculated to be as low as 7 nm for 7.5% Y and 22 nm for 1% Y alloy. The grain size was retained within 35 nm even after annealing for 1 h at 800 °C. Transmission electron microscopy (TEM) analysis substantiates the formation of ultra-fine grained nanostructures after milling. Microhardness value of the as-milled samples was quite high (3.0–4.75 GPa) compared to that of pure Cu. The hardness value increased with increasing annealing temperatures up to 400 °C for the alloys containing 3–7.5% Y, and thereafter it showed a decreasing trend. The increase in the hardness after annealing is attributed to the formation of uniformly distributed ultrafine intermetallic phases in the nanocrystalline grains. The stabilization effect is achieved due to

Rotating speed effect on electronic transport behaviors of Ni–Nb–Zr–H glassy alloys

International Nuclear Information System (INIS)

Fukuhara, Mikio

2012-01-01

Highlights: ► The electronic transport behaviors of (Ni 0.39 Nb 0.25 Zr 0.35 ) 100−y H y (0 ≤ y ≤ 15) glassy alloys, which produced by rotating (or quenching) speeds of 3000 and 10,000 rpm, have been studied as a function of hydrogen content. ► The resistivity for (Ni 0.39 Nb 0.25 Zr 0.35 ) 97.8 H 2.2 alloy, produced by rotating speed of 10,000 rpm, displayed 0.1 nΩ cm, which is 0.01% of silver (1.62 μΩ cm) at room temperature, between 40 and 252 K. ► Supercooling of the molten alloy induces a superior ballistic conductor and a room-temperature Coulomb oscillation. - Abstract: The electronic transport behaviors of (Ni 0.39 Nb 0.25 Zr 0.35 ) 100−y H y (0 ≤ y ≤ 15) glassy alloys, produced by rotating (or quenching) speeds of 3000 and 10,000 rpm, have been studied as a function of hydrogen content. These alloys show semiconducting, superior ballistic transport, superconducting and electric current-induced Coulomb oscillation, as hydrogen content increases. The resistivity for (Ni 0.39 Nb 0.25 Zr 0.35 ) 97.8 H 2.2 alloy, produced by rotating speed of 10,000 rpm, displayed 0.1 nΩ cm, which is 0.01% of silver (1.62 μΩ cm) at room temperature, between 40 and 252 K. The Coulomb oscillation of the 10,000 rpm-(Ni 0.39 Nb 0.25 Zr 0.35 ) 95.2 H 4.8 alloy is about 4-fold larger than that of the 3000 rpm-(Ni 0.39 Nb 0.25 Zr 0.35 ) 91.1 H 8.9 alloy. Supercooling of the molten alloy induces a superior ballistic conductor and a room-temperature Coulomb oscillation at lower and higher hydrogen contents, respectively.

Modulated ordering Nb-H alloys

International Nuclear Information System (INIS)

Kajitani, T.; Brun, T.O.; Mueller, M.H.; Birnbaum, H.K.; Makenas, B.J.

1979-01-01

Ordering reactions in α' and β-NbH alloys have been investigated using elastic theory. The α'-β and β-lambda phase transformations are driven by the elastic interaction in the niobium lattice distorted by the protons on the t-site interstitials. The β phase is shown to have a three dimensional structure. The fundamental period of the long range modulation along the c-axis in the lambda-phase, an incommensurated β phase, is approximately 5 lattice constants

Effect of time and temperature on grain size of V and V-Cr-Ti alloys

International Nuclear Information System (INIS)

Natesan, K.; Rink, D.L.

1996-01-01

Grain growth studies were conducted to evaluate the effect of time and temperature on the grain size of pure V, V-4 wt.%Cr-4 wt.%Ti, and V-5 wt.%Cr-5 wt.%Ti alloys. The temperatures used in the study were 500, 650, 800, and 1000 degrees C, and exposure times ranged between 100 and ∼5000 h. All three materials exhibited negligible grain growth at 500, 650, and 800 degrees C, even after ∼5000 h. At 1000 degrees C, pure V showed substantial grain growth after only 100 h, and V-4Cr-4Ti showed growth after 2000 h, while V-5Cr-5Ti showed no grain growth after exposure for up to 2000 h

X-ray-induced dissociation of H.sub.2O and formation of an O.sub.2-H.sub.2 alloy at high pressure

Science.gov (United States)

Mao, Ho-kwang [Washington, DC; Mao, Wendy L [Washington, DC

2011-11-29

A novel molecular alloy of O.sub.2 and H.sub.2 and a method of producing such a molecular alloy are provided. When subjected to high pressure and extensive x-radiation, H.sub.2O molecules cleaved, forming O--O and H--H bonds. In the method of the present invention, the O and H framework in ice VII was converted into a molecular alloy of O.sub.2 and H.sub.2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrate that this crystalline solid differs from previously known phases.

Elemental volatility of HT-9 fusion reactor alloy

International Nuclear Information System (INIS)

Henslee, S.P.; Neilson, R.M. Jr.

1985-01-01

The volatility of elemental constituents from HT-9, a ferritic steel, proposed for fusion reactor structures, was investigated. Tests were conducted in flowing air at temperatures from 800 to 1200 0 C for durations of 1 to 20 h. Elemental volatility was calculated in terms of the weight fraction of the element volatilized from the initial alloy; molybdenum, manganese, and nickel were the primary constituents volatilized. Comparisons with elemental volatilities observed for another candidate fusion reactor materials. Primary Candidate Alloy (PCA), an austenitic stainless steel, indicate significant differences between the volatilities of these steels that may impact fusion reactor safety analysis and alloy selection. Scanning electron microscopy and energy dispersive spectrometry were used to investigate the oxide layers formed on HT-9 and to measure elemental contents within these layers

Pitting of Incoloy 800 in presence of CuII

International Nuclear Information System (INIS)

Bianchi, G.L.; Alvarez, M.G.

1993-01-01

The pitting behaviour of Incoloy 800 in presence of Cu II ions, at 60 degrees C and 280 degrees C was studied by long term exposition of specimens in aqueous cupric chloride solutions. At 60 degrees C experiments were performed in aerated (7 ppm O 2 ) and deaerated solutions containing 500, 1000, 2000, 10000 and 20000 ppm CuCl 2 . At 280 degrees C experiments were performed in deaerated 20 ppm, 50 ppm and 100 ppm CuCl 2 solutions. During each experiment the open circuit potential of the alloy was measured as a function of time. After corrosion test the specimens were examined by Scanning Electron Microscopy for the presence of pits. In another set of experiments potentiodynamic anodic polarization curves were used to determine the pitting potential of Incoloy 800 in deaerated NaCl solutions at chloride concentrations and pH values corresponding to those possessed by solutions containing 20 ppm to 20000 ppm CuCl 2 . At 60 degrees C pitting was observed in those solutions where the CuCl 2 concentration is higher than 1000 ppm. At 280 degrees C pitting was found in the specimens exposed to those solutions where the CuCl 2 concentration was higher than 20 ppm. (author). 3 refs

Study of neutron irradiation on F82H alloys by Mössbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Huang, S.S., E-mail: h.shaosong@ht8.ecs.kyoto-u.ac.jp; Kitao, S.; Kobayashi, Y.; Yoshiie, T.; Xu, Q.; Sato, K.; Seto, M.

2015-01-15

The effects of neutron irradiation on F82H ferritic/martensitic stainless steel and its model alloys were studied by Mössbauer spectroscopy. The microstructural damage mechanisms of these alloys, during the void incubation period were interpreted using the short range order (SRO) parameters. Results show that within Fe–8Cr alloy, the atoms in the nearest neighbor (NN) of the Fe nuclei were inhomogeneous, prior to irradiation. A configuration trapping model of Cr supported the negative average SRO observed for the NN shells in our Fe–Cr alloys. We found that irradiation also accelerated the SRO in Fe–8Cr through a diffusion mechanism, where Cr atom repulsion was concentration dependent. Finally, comparative studies were conducted on F82H model alloys using the present Mössbauer measurements and our previously reported work on positron annihilation spectroscopy, which further established that irradiation of the alloys promoted the growth of a M{sub 23}C{sub 6} complex.

The microstructure of Incoloy 800 H after long-time creep

International Nuclear Information System (INIS)

Sheng Zhongqi; Katerbau, K.

1993-01-01

The microstructural change of Incoloy 800 H after creep tests with low loads and long rupture time has been investigated. Cavities nucleate at one side of M 23 C 6 carbide particles on grain boundaries. Microcrack propagate by passing through a string of these cavities, M 23 C 6 carbide particles on grain boundaries have a coherent relationship with one of both neighbouring grains, so grain boundaries are strengthened, and the strengthening effect can be estimated for enhanced activation energy. G phase precipitation can be observed on grain boundaries, but no γ' phase particles can be found. Dislocation substructure is different from the typical recovery creep. Dislocation piles appear near M 23 C 6 carbide particles on grain boundaries. Subgrain structure poorly develop and network distribution of dislocation can remain after relative long creep

Study of a chromia-forming alloy behavior as interconnect material for High Temperature Vapor Electrolysis

International Nuclear Information System (INIS)

Guillou, S.

2011-01-01

In High Temperature Vapor Electrolysis (HTVE) system, the materials chosen for the inter-connectors should have a good corrosion behaviour in air and in H 2 -H 2 O mixtures at 800 C, and keep a high electronic conductivity over long durations as well. In this context, the first goal of this study was to evaluate a commercial ferritic alloy (the K41X alloy) as interconnect for HTVE application. Oxidation tests in furnace and in microbalance have therefore been carried out in order to determine oxidation kinetics. Meanwhile, the Area Specific Resistance (ASR) was evaluated by Contact Resistance measurements performed at 800 C. The second objective was to improve our comprehension of chromia-forming alloys oxidation mechanism, in particular in H 2 /H 2 O mixtures. For that purpose, some specific tests have been conducted: tracer experiments, coupled with the characterization of the oxide scale by PEC (Photo-Electro-Chemistry). This approach has also been applied to the study of a LaCrO 3 perovskite oxide coating on the K41X alloy. This phase is indeed of high interest for HTVE applications due to its high conductivity properties. This latter study leads to further understanding on the role of lanthanum as reactive element, which effect is still under discussion in literature.In both media at 800 C, the scale is composed of a Cr 2 O 3 /(Mn,Cr) 3 O 4 duplex scale, covered in the case of H 2 -H 2 O mixture by a thin scale made of Mn 2 TiO 4 spinel. In air, the growth mechanism is found to be cationic, in agreement with literature. The LaCrO 3 coating does not modify the direction of scale growth but lowers the growth kinetics during the first hundreds hours. Moreover, with the coating, the scale adherence is favored and the conductivity appears to be slightly higher. In the H 2 -H 2 O mixture, the growth mechanism is found to be anionic. The LaCrO 3 coating diminishes the oxidation kinetics. Although the scale thickness is about the same in both media, the ASR parameter

A sulfidation-resistant nickel-base alloy

International Nuclear Information System (INIS)

Lai, G.Y.

1989-01-01

For applications in mildly to moderately sulfidizing environments, stainless steels, Fe-Ni-Cr alloys (e.g., alloys 800 and 330), and more recently Fe-Ni-Cr-Co alloys (e.g., alloy 556) are frequently used for construction of process equipment. However, for many highly sulfidizing environments, few existing commercial alloys have adequate performance. Thus, a new nickel-based alloy containing 27 wt.% Co, 28 wt.% Cr, 4 wt.% Fe, 2.75 wt.% Si, 0.5 wt.% Mn and 0.05 wt.% C (Haynes alloy HR-160) was developed

Caustic stress corrosion cracking of Inconel-600, Incoloy-800, and Type 304 stainless steel

International Nuclear Information System (INIS)

Theus, G.J.

1976-01-01

High-temperature electrochemical tests have resulted in the stress corrosion cracking of Inconel-600 and Incoloy-800 (registered trademarks, International Nickel Company), and Type 304 stainless steel in caustic solutions. Results show that stress corrosion cracking of these alloys can be prevented or accelerated by varying their electrochemical potential. To a certain extent, the same effect can be achieved by altering the gas atmosphere above the test solution from a pure nitrogen cover gas to a mixture of 5 percent H 2 and 95 percent N 2 . The effect of the cover gas can then be negated by adjusting the specimen's electrochemical potential either to cause or to inhibit stress corrosion cracking. Some specifics of the test results reveal that in deoxygenated caustic solutions, Inconel-600 cracks intergranularly at mildly anodic potentials; Incoloy-800 cracks transgranularly at reduced potentials (at or near the open circuit potential) and intergranularly at highly oxidizing potentials; and cracking is mixed (transgranular/intergranular) for Type 304 stainless steel at or near the open circuit potential. The severity of cracking for both Inconel-600 and Incoloy-800 in deoxygenated caustic solutions is reduced by giving the materials a simulated post-weld heat treatment (1150 0 F for 18 h). Test results on Inconel-600 show that high-carbon (0.06 percent) material cracks less severely than low-carbon (0.02 percent) material, in both the simulated post-weld heat-treated condition and the mill-annealed condition

The influence of pH on the corrosion of medium strength aerospace alloy 8090, 2091 and 2014

DEFF Research Database (Denmark)

Ambat, Rajan; Dwarakadasa, E.S.

1992-01-01

The influence of pH on the corrosion behaviour of two aluminium-lithium-copper-magnesium-zirconium (8090 and 2091) alloys was studied and compared with a standard aircraft alloy, 2014 (Al-4.4% Cu) and 99.9% pure Al. In constant exposure and potentiodynamic polarization studies conducted in 3.5% Na......Cl solution having different pH values, all the alloys exhibited high corrosion rates in acidic and alkaline environments, with a minimum in less hostile environments close to neutral pH. The pitting potentials for aluminium-lithium alloys were slightly lower than those for 2014 and pure Al. The effect of p......H on the passive current density was also less for aluminium-lithium alloys....

Time-temperature-sensitization and time-temperature-precipitation behavior of alloy 625

International Nuclear Information System (INIS)

Koehler, M.; Heubner, U.

1996-01-01

Time-Temperature-Sensitization diagrams have been established for a low-carbon version of alloy 625 (UNS N06625). Sensitization in terms of a 50 microm (2 mils) intergranular penetration criterion starts after about 3 h aging time at 750 C (soft annealed condition) or after less than 1 h aging time at 800 C (solution annealed condition) when tested according to ASTM-G 28 method A. Grain boundary precipitation of carbides occurs during aging of both the soft annealed and the solution annealed material, but the soft annealed material exhibits a more pronounced general precipitation of Ni 3 (Nb,Mo) phase giving rise to more distinct loss of ductility. Sensitization of alloy 625 may be retarded by lowering its iron content

Precipitation kinetics of the phase. gamma. ' in Fe-Ni-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Tavassoli, A.A.; Pozarnik, F.

1984-04-01

The authors investigated the precipitation and coalescence kinetics of the ..gamma..'phase in alloy 800, an austenitic steel with 33% Ni, 20% Cr and small amounts of Ti and Al. The results led to a law concerning the variation with temperature, ageing, and chemical composition of the particle size in the ..gamma..'phase. This law was used to calculate the variation of the elasticity limit of the alloy due to the formation of the ..gamma..'phase. The calculations were based on the theories of interaction of (weakly and strongly coupled) dislocation pairs with coherent particles ordered without constraint; the anisotropy of tension along the dislocation line was taken into account as well as the influence of the deformation induced by the misfit. A comparison with experimental results shows that averaging does not occur until 2x10/sup 5/ h at operating temperatures below 800 K.

Lamellar boundary alignment of DS-processed TiAl-W alloys by a solidification procedure

Science.gov (United States)

Jung, In-Soo; Oh, Myung-Hoon; Park, No-Jin; Kumar, K. Sharvan; Wee, Dang-Moon

2007-12-01

In this study, a β solidification procedure was used to align the lamellae in a Ti-47Al-2W (at.%) alloy parallel to the growth direction. The Bridgman technique and the floating zone process were used for directional solidification. The mechanical properties of the directionally solidified alloy were evaluated in tension at room temperature and at 800°C. At a growth rate of 30 mm/h (with the floating zone approach), the lamellae were well aligned parallel to the growth direction. The aligned lamellae yielded excellent room temperature tensile ductility. The tensile yield strength at 800°C was similar to that at room temperature. The orientation of the γ lamellar laths in the directionally solidified ingots, which were manufactured by means of a floating zone process, was identified with the aid of electron backscattered diffraction analysis. On the basis of this analysis, the preferred growth direction of the bcc-β dendrites that formed at high temperatures close to the melting point was inferred to be [001]β at a growth rate of 30 mm/h and [111]β at a growth rate of 90 mm/h.

Temperature dependence of the dynamic fracture toughness of the alloy Incoloy 800 after cold work

International Nuclear Information System (INIS)

Krompholz, K.; Ullrich, G.

1991-02-01

Precracked charpy-V-notch specimens of the iron-nickel base alloy Incoloy 800 in the as-received condition and after cold work have been tested using an instrumented impact tester (hammer) in the temperature range 293 ≤ T/K ≤ 1223. The specific impact energies were determined by dial readings, from the integration of the load versus time and the load versus load point displacement diagrams; in all cases the agreement was excellent. The specific impact energies and the impulses are correlated with the test temperature and with the degree of cold work, respectively. The dynamic fracture toughness values were determined following the equivalent energy approach. In all cases a distinct decrease of the mechanical properties in the range between the as-received state and after 5 % cold work was found. The temperature behaviour of the impact energies clearly reveals an increase of its value between room temperature and 673 K. This increase is distinctly reduced after cold work. The dynamic fracture toughness decreases with increasing temperature. The fracture surfaces clearly show elasto-plastic fracture behaviour of the material in the temperature regime investigated. (author) 19 figs., 3 tabs., 7 refs

Local atomic structure and chemical order in amorphous SiGe:H and SiC:H alloys

International Nuclear Information System (INIS)

Pisarkiewicz, T.; Stapinski, T.

1994-01-01

The local structure and chemical ordering in amorphous hydrogenated silicon-germanium and silicon-carbon alloys were analyzed mainly with the help of extended x-ray absorption fine structure (EXAFS) spectroscopy, Raman scattering and electron diffraction. Ge-Ge and Ge-Si distances were found to be independent of concentration and the composition of the first coordination shell around Ge is consistent with a random mixing of the two species in a-Si 1-x Ge:H alloy. The first-coordination-shell average bond lengths for Si-Si and SiC in a-Si 1-x C x :H are also constant with concentration x and the comparison of the first coordination shell composition around Si with average concentration indicates that the alloys tends to be chemically ordered. The degree of crystallinity in microcrystalline Si films determined by EXAFS is in agreement with that obtained in Raman scattering analysis. (author). 16 refs, 5 figs

V S30, slope, H 800 and f 0: performance of various site-condition proxies in reducing ground-motion aleatory variability and predicting nonlinear site response

Science.gov (United States)

Derras, Boumédiène; Bard, Pierre-Yves; Cotton, Fabrice

2017-09-01

The aim of this paper is to investigate the ability of various site-condition proxies (SCPs) to reduce ground-motion aleatory variability and evaluate how SCPs capture nonlinearity site effects. The SCPs used here are time-averaged shear-wave velocity in the top 30 m ( V S30), the topographical slope (slope), the fundamental resonance frequency ( f 0) and the depth beyond which V s exceeds 800 m/s ( H 800). We considered first the performance of each SCP taken alone and then the combined performance of the 6 SCP pairs [ V S30- f 0], [ V S30- H 800], [ f 0-slope], [ H 800-slope], [ V S30-slope] and [ f 0- H 800]. This analysis is performed using a neural network approach including a random effect applied on a KiK-net subset for derivation of ground-motion prediction equations setting the relationship between various ground-motion parameters such as peak ground acceleration, peak ground velocity and pseudo-spectral acceleration PSA ( T), and M w, R JB, focal depth and SCPs. While the choice of SCP is found to have almost no impact on the median ground-motion prediction, it does impact the level of aleatory uncertainty. V S30 is found to perform the best of single proxies at short periods ( T < 0.6 s), while f 0 and H 800 perform better at longer periods; considering SCP pairs leads to significant improvements, with particular emphasis on [ V S30- H 800] and [ f 0-slope] pairs. The results also indicate significant nonlinearity on the site terms for soft sites and that the most relevant loading parameter for characterising nonlinear site response is the "stiff" spectral ordinate at the considered period.[Figure not available: see fulltext.

Stress corrosion cracking of Ni-Fe-Cr alloys in acid sulfate environments relevant to CANDU steam generators

Energy Technology Data Exchange (ETDEWEB)

Persaud, S.Y.; Carcea, A.G., E-mail: suraj.persaud@mail.utoronto.ca [Univ. of Toronto, Toronto, ON (Canada); Huang, J.; Korinek, A.; Botton, G.A. [McMaster Univ., Hamilton, ON (Canada); Newman, R.C. [Univ. of Toronto, Toronto, ON (Canada)

2014-07-01

Ni-Fe-Cr alloys used in nuclear plants have been found susceptible to stress corrosion cracking (SCC) in acid sulfate environments. Electrochemical measurements and SCC tests were done using Ni, Alloy 600, and Alloy 800 in acid sulfate solutions at 315 {sup o}C. Electrochemical measurements suggested that sulfate is a particularly aggressive anion in mixed chloride systems. Cracks with lengths in excess of 300 μm were present on stressed Alloy 800 samples after 60 hours. High resolution analytical electron microscopy was used to extract a crack tip from an Alloy 800 sample and draw final conclusions with respect to the mechanism of SCC. (author)

Synodic periods of asteroids 333, 402, 481, and 800

Science.gov (United States)

Denchev, P.; Shkodrov, V.; Ivanova, V.

2000-08-01

The asteroids 333 Badenia, 402 Chloe, 481 Emita and 800 Kressmannia have been observed using photoelectric photometry during their 1997 apparations. The obtained synodic periods are: 333 Badenia - 9.96 h; 402 Chloe - 7.111 h; 481 Emita - 14.35 h and 800 Kressmannia - 4.457 h. There are no published periods so far for the first three. We obtained the phase parameters of 402 Chloe, they are H=8.86 and G=0.11.

Carburization of austenitic alloys by gaseous impurities in helium

International Nuclear Information System (INIS)

Lai, G.Y.; Johnson, W.R.

1980-03-01

The carburization behavior of Alloy 800H, Inconel Alloy 617 and Hastelloy Alloy X in helium containing various amounts of H 2 , CO, CH 4 , H 2 O and CO 2 was studied. Corrosion tests were conducted in a temperature range from 649 to 1000 0 C (1200 to 1832 0 F) for exposure time up to 10,000 h. Four different helium environments, identified as A, B, C, and D, were investigated. Concentrations of gaseous impurities were 1500 μatm H 2 , 450 μatm CO, 50 μatm CH 4 and 50 μatm H 2 O for Environment A; 200 μatm H 2 , 100 μatm CO, 20 μatm CH 4 , 50 μatm H 2 O and 5 μatm CO 2 for Environment B; 500 μatm H 2 , 50 μatm CO, 50 μatm CH 4 and 2 O for Environment C; and 500 μatm H 2 , 50 μatm CO, 50 μatm CH 4 and 1.5 μatm H 2 O for Environment D. Environments A and B were characteristic of high-oxygen potential, while C and D were characteristic of low-oxygen potential. The results showed that the carburization kinetics in low-oxygen potential environments (C and D) were significantly higher, approximately an order of magnitude higher at high temperatures, than those in high-oxygen potential environments (A and B) for all three alloys. Thermodynamic analyses indicated no significant differences in the thermodynamic carburization potential between low- and high-oxygen potential environments. It is thus believed that the enhanced carburization kinetics observed in the low-oxygen potential environments were related to kinetic effects. A qualitatively mechanistic model was proposed to explain the enhanced kinetics. The present results further suggest that controlling the oxygen potential of the service environment can be an effective means of reducing carburization of alloys

Gd{sub 90}Co{sub 2.5}Fe{sub 7.5} alloy displaying enhanced magnetocaloric properties

Energy Technology Data Exchange (ETDEWEB)

Provenzano, V., E-mail: virgil12@nist.gov [Materials Science and Engineering Division, NIST, Gaithersburg, MD 20899-8552 (United States); Shull, R.D., E-mail: robert.shull@nist.gov [Materials Science and Engineering Division, NIST, Gaithersburg, MD 20899-8552 (United States); Kletetschka, G., E-mail: kletetschka@gmail.com [Faculty of Science, Charles University, Prague 12843 (Czech Republic); Institute of Geology, Academy of Science of the Czech Republic, v.v.i., Prague 16500 (Czech Republic); Stutzman, P.E., E-mail: paul.stutzman@nist.gov [Materials and Structural Systems Division, NIST, Gaithersburg, MD 20899-861 (United States)

2015-02-15

Highlights: • The Gd{sub 90}Co{sub 2.5}Fe{sub 7.5} alloy displays superior magnetocaloric properties than Gd. • Alloy’s superior properties at relatively low field values: 400, 800 kA/m (0.5, 1 T). • We proposed two possible mechanisms for the Gd-based alloy enhanced properties. • We indicated a pathway for further improving the alloy magnetocaloric properties. - Abstract: We report on the discovery of a new Gd{sub 90}Co{sub 2.5}Fe{sub 7.5} alloy exhibiting superior magnetocaloric properties compared to those of gadolinium. We present magnetically-derived entropy change, ΔS{sub M}, computed from magnetic data, and thermally-derived temperature change, ΔT{sub ad}, obtained from direct thermal measurements together with their respective MCE peaks for the alloy and gadolinium. The MCE peaks of the alloy are taller and broader than the corresponding MCE peaks of gadolinium. Correspondingly, the refrigeration capacity (RC) values of the alloy computed from magnetic and thermal MCEs for field changes, ΔH, of 400 kA/m (0.5 T) and 800 kA/m (1 T) are about 20% larger than those of gadolinium. Two possible mechanisms are proposed to account for the improved magnetocaloric properties of gadolinium alloyed with small amounts of Co and Fe, thereby pointing out a different methodology to use in the search for improved low field magnetic refrigerants.

The scale constituents and spalling characteristics of Ni-Fe(O-60%) alloys oxidized in air at 800-12000C

International Nuclear Information System (INIS)

Tomlinson, W.J.; Gardner, M.J.; Kowalski, R.J.

1977-01-01

The spalling behaviour of scales on Ni-Fe alloys containing 0, 2, 10, 20, 30, 40, 50 and 60% Fe oxidized in air at 900, 1000, 1100 and 1200 0 C for periods up to 165 h have been investigated. The phases present and their relative amounts in the scales formed at 1200 0 C have been determined. Spalling was most severe in the Ni-30% Fe alloy, which had a scale consisting of 30% Nisub(x)Fesub(3-x)O 4 and 70% Nisub(1-x)Fesub(x)O. (author)

High-temperature steam oxidation testing of select advanced replacement alloys for potential core internals

Energy Technology Data Exchange (ETDEWEB)

Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-05-19

Coupons from a total of fourteen commercial and custom fabricated alloys were exposed to 1 bar full steam with ~10 ppb oxygen content at 600 and 650°C. The coupons were weighed at 500-h intervals with a total exposure time of 5,000 h. The fourteen alloys are candidate alloys selected under the ARRM program, which include three ferritic steels (Grade 92, 439, and 14YWT), three austenitic stainless steels (316L, 310, and 800), seven Ni-base superalloys (X750, 725, C22, 690, 625, 625 direct-aging, and 625- plus), and one Zr-alloy (Zr–2.5Nb). Among the alloys, 316L and X750 are served as reference alloys for low- and high-strength alloys, respectively. The candidate Ni-base superalloy 718 was procured too late to be included in the tests. The corrosion rates of the candidate alloys can be approximately interpreted by their Cr, Ni and Fe content. The corrosion rate was significantly reduced with increasing Cr content and when Ni content is above ~15 wt%, but not much further reduced when Fe content is less than ~55 wt%. Simplified thermodynamics analyses of the alloy oxidation provided reasonable indications for the constituents of oxide scales formed on the alloys and explanations for the porosity and exfoliation phenomena because of the nature of specific types of oxides.

Effect of Al Hot-Dipping on High-Temperature Corrosion of Carbon Steel in N2/0.1% H2S Gas

Directory of Open Access Journals (Sweden)

Muhammad Ali Abro

2016-02-01

Full Text Available High-temperature corrosion of carbon steel in N2/0.1% H2S mixed gas at 600–800 °C for 50–100 h was studied after hot-dipping in the aluminum molten bath. Hot-dipping resulted in the formation of the Al topcoat and the Al-Fe alloy layer firmly adhered on the substrate. The Al-Fe alloy layer consisted primarily of a wide, tongue-like Al5Fe2 layer and narrow Al3Fe layer. When corroded at 800 °C for 100 h, the Al topcoat partially oxidized to the protective but non-adherent α-Al2O3 layer, and the interdiffusion converted the Al-Fe alloy layer to an (Al13Fe4, AlFe3-mixed layer. The interdiffusion also lowered the microhardness of the hot-dipped steel. The α-Al2O3 layer formed on the hot-dipped steel protected the carbon steel against corrosion. Without the Al hot-dipping, the carbon steel failed by forming a thick, fragile, and non-protective FeS scale.

Resistance of Incoloy 800 steam generator tube to pitting corrosion in PWR secondary water at 250°C

International Nuclear Information System (INIS)

Schvartzman, Mônica M.A.M.; Albuquerque, Adriana Silva de; Esteves, Luiza; Rabello, Emerson G.; Mansur, Fábio Abud

2017-01-01

The steam generator (SG) is one of the main components of a PWR, so the performance of this type of nuclear power plant depends to a large extent on the trouble-free operation of SGs. Its degradation significantly affects the overall plant performance. Alloy 800NG (Incoloy® 800) is a nickel-iron-chromium alloy used for steam generator tubes in PWRs due to their high strength, good workability and resistance to corrosion. This behavior is attributed to the protective oxide film formed on the metal surface by contact with the high temperature pressurized water. However, chloride is one of major SG impurities that cause the breakdown of the passive film and initiate localized corrosion in passive metals as Alloy 800NG. The aim of this study is to provide information about the pitting corrosion behavior of the Incoloy® 800 steam generator tube under normal secondary circuit parameters (250 deg C and 5 MPa) and abnormal conditions of operation (presence of chloride ions in the secondary water). For this, optical microscopy, XRD and EDS analysis and electrochemical tests have been carried out under simulated PWR secondary water operating conditions. The susceptibility to pitting corrosion was evaluated using electrochemical tests and the oxide layer formed on material was examined by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) analyses. (author)

Resistance of Incoloy 800 steam generator tube to pitting corrosion in PWR secondary water at 250°C

Energy Technology Data Exchange (ETDEWEB)

Schvartzman, Mônica M.A.M. [Pontifícia Universidade Católica de Minas Gerais (PUC-Minas), Belo Horizonte, MG (Brazil); Albuquerque, Adriana Silva de; Esteves, Luiza; Rabello, Emerson G.; Mansur, Fábio Abud, E-mail: monicacdtn@gmail.com, E-mail: asa@cdtn.br, E-mail: luiza.esteves@cdtn.br, E-mail: egr@cdtn.br, E-mail: fametalurgica@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The steam generator (SG) is one of the main components of a PWR, so the performance of this type of nuclear power plant depends to a large extent on the trouble-free operation of SGs. Its degradation significantly affects the overall plant performance. Alloy 800NG (Incoloy® 800) is a nickel-iron-chromium alloy used for steam generator tubes in PWRs due to their high strength, good workability and resistance to corrosion. This behavior is attributed to the protective oxide film formed on the metal surface by contact with the high temperature pressurized water. However, chloride is one of major SG impurities that cause the breakdown of the passive film and initiate localized corrosion in passive metals as Alloy 800NG. The aim of this study is to provide information about the pitting corrosion behavior of the Incoloy® 800 steam generator tube under normal secondary circuit parameters (250 deg C and 5 MPa) and abnormal conditions of operation (presence of chloride ions in the secondary water). For this, optical microscopy, XRD and EDS analysis and electrochemical tests have been carried out under simulated PWR secondary water operating conditions. The susceptibility to pitting corrosion was evaluated using electrochemical tests and the oxide layer formed on material was examined by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) analyses. (author)

Wetting phenomena of Al-Cu alloys on sapphire below 800 deg. C

International Nuclear Information System (INIS)

Klinter, Andreas J.; Leon-Patino, Carlos A.; Drew, Robin A.L.

2010-01-01

Using a modified dispensed drop method, a decrease in contact angle on sapphire from pure aluminum to low-copper-containing Al alloys (7-12 wt.%) was found; with higher copper additions θ transitions to the non-wetting regime. Atomic force microscopy on long-term samples showed a significantly increased surface roughness beneath the drop. Using high-resolution transmission electron microscopy, the reaction product at the interface was identified as CuAl 2 O 4 for Al-7Cu and Al 2 O 3 for an Al-99.99 drop. X-ray photoelectron spectroscopy further confirmed the formation of CuAl 2 O 4 under CuAl 2 drops. Spinel formation is caused by reaction of the alloy with residual oxygen in the furnace that is transported along the interface as modeled by thermodynamic simulations. The formation of CuAl 2 O 4 causes the reduced σ sl and hence the improved wettability of sapphire by low-copper-containing alloys compared to pure aluminum. The main reason for the increase in θ with higher copper contents is the increasing σ lv of the alloy.

Influence of hydrogen on the thermoelectric power of palladium alloyed with neighbouring elements: I. Pd/Ru/H and Pd/Rh/H alloys

CERN Document Server

Szafranski, A W

2003-01-01

Pd/Ru and Pd/Rh alloys have been loaded with hydrogen in high-pressure conditions. The resulting hydrogen contents were close to the stoichiometric composition, H/(Pd + Me) = 1. Lower hydrogen contents have been obtained by successive partial desorptions. The thermoelectric power and electrical resistance of one- and two-phase alloys have been measured simultaneously in the temperature range between 80 and 300 K. A Nordheim-Gorter type correlation of the two quantities has been observed in many cases and the partial thermopowers corresponding to electron-phonon scattering and lattice disorder could be determined. The observed anomalous behaviour of the total and partial thermopowers is attributed to virtual bound states of ruthenium or rhodium.

Compression behavior of Fe-Si-H alloys

Science.gov (United States)

Tagawa, S.; Ohta, K.; Hirose, K.; Ohishi, Y.

2015-12-01

Although the light elements in the Earth's core are still enigmatic, hydrogen has recently been receiving much attention. Planetary formation theory suggested that a large amount of water, much more than is in the oceans, could have been brought to the Earth during its accretion. Hydrogen is a strong siderophile element and could be incorporated into the core as a consequence of a reaction between water and molten iron in a magma ocean [Okuchi, 1997 Science]. Nevertheless, the effect of hydrogen on the property of iron is not well known so far. Here, we have experimentally examined the compression behavior of hcp Fe0.88Si0.12Hx (6.5 wt.% Si) at two different hydrogen concentrations (x = 0.7 and 0.9). Fe0.88Si0.12 foil was loaded into a diamond-anvil cell, and then liquid hydrogen was introduced to a sample chamber below 20 K. Hydrogenation occurred upon thermal annealing below 1500 K at 25-62 GPa, and hcp Fe0.88Si0.12Hx was obtained as a single phase. Unlike the Fe-H alloy, hydrogen did not fully occupy the octahedral sites even under hydrogen-saturated conditions. Two compression curves, one from 25 to 136 GPa, and the other from 62 to 128 GPa, were obtained at room temperature. While the effect of hydrogen on the compressibility of iron has been controversial in earlier experimental studies [Hirao et al., 2004 GRL; Pépin et al., 2014 PRL], our data indicate that the compressibility of Fe0.88Si0.12Hx alloy does not change with changing hydrogen content from x = 0 to 0.9. Such compression behavior observed is consistent with the recent ab initio calculations for hcp Fe-H alloys by Caracas[2015 GRL]. The extrapolation of present data to the outer core pressure and temperature range, assuming thermal expansivity is the same as that for iron and there is no density difference between solid and liquid, shows that the density of Fe0.88Si0.12H0.3 matches the PREM in the whole outer core within 1%.

Wetting phenomena of Al-Cu alloys on sapphire below 800 deg. C

Energy Technology Data Exchange (ETDEWEB)

Klinter, Andreas J., E-mail: andreas.klinter@mail.mcgill.ca [Mining and Materials Engineering, McGill University, M.H. Wong Building, 3610 University Street, Montreal, QC, H3A 2B2 (Canada); Leon-Patino, Carlos A. [Instituto de Investigaciones Metalurgicas, Universidad Michoacana de San Nicolas de Hidalgo, Apdo. Postal 888, CP 58000 Morelia, Michoacan (Mexico); Drew, Robin A.L. [Faculty of Engineering and Computer Science, Concordia University, 1455 Maisonneuve Blvd, EV 2.169, Montreal, QC, H3G 1M8 (Canada)

2010-02-15

Using a modified dispensed drop method, a decrease in contact angle on sapphire from pure aluminum to low-copper-containing Al alloys (7-12 wt.%) was found; with higher copper additions {theta} transitions to the non-wetting regime. Atomic force microscopy on long-term samples showed a significantly increased surface roughness beneath the drop. Using high-resolution transmission electron microscopy, the reaction product at the interface was identified as CuAl{sub 2}O{sub 4} for Al-7Cu and Al{sub 2}O{sub 3} for an Al-99.99 drop. X-ray photoelectron spectroscopy further confirmed the formation of CuAl{sub 2}O{sub 4} under CuAl{sub 2} drops. Spinel formation is caused by reaction of the alloy with residual oxygen in the furnace that is transported along the interface as modeled by thermodynamic simulations. The formation of CuAl{sub 2}O{sub 4} causes the reduced {sigma}{sub sl} and hence the improved wettability of sapphire by low-copper-containing alloys compared to pure aluminum. The main reason for the increase in {theta} with higher copper contents is the increasing {sigma}{sub lv} of the alloy.

Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-18

FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO₂ or ZrO₂. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

Basic principles of creating a new generation of high- temperature brazing filler alloys

Science.gov (United States)

Kalin, B. A.; Suchkov, A. N.

2016-04-01

The development of new materials is based on the formation of a structural-phase state providing the desired properties by selecting the base and the complex of alloying elements. The development of amorphous filler alloys for a high-temperature brazing has its own features that are due to the limited life cycle and the production method of brazing filler alloys. The work presents a cycle of analytical and experimental materials science investigations including justification of the composition of a new amorphous filler alloy for brazing the products from zirconium alloys at the temperature of no more than 800 °C and at the unbrazing temperature of permanent joints of more than 1200 °C. The experimental alloys have been used for manufacture of amorphous ribbons by rapid quenching, of which the certification has been made by X-ray investigations and a differential-thermal analysis. These ribbons were used to obtain permanent joints from the spacer grid cells (made from the alloy Zr-1% Nb) of fuel assemblies of the thermal nuclear reactor VVER-440. The brazed samples in the form of a pair of cells have been exposed to corrosion tests in autoclaves in superheated water at a temperature of 350 °C, a pressure of 160 MPa and duration of up to 6,000 h. They have been also exposed to destructive tests using a tensile machine. The experimental results obtained have made it possible to propose and patent a brazing filler alloy of the following composition: Zr-5.5Fe-(2.5-3.5)Be-1Nb-(5-8)Cu-2Sn-0.4Cr-(0.5-1.0)Ge. Its melting point is 780 °C and the recommended brazing temperature is 800°C.

Creep strength and microstructure in 23Cr-45Ni-7W Alloy (HR6W) and Ni-base superalloys for advanced USC boilers

Energy Technology Data Exchange (ETDEWEB)

Semba, Hiroyuki; Okada, Hirokazu; Yonemura, Mitsuharu; Igarashi, Masaaki [Sumitomo metal Industries, Ltd., Hyogo (Japan). Corporate Research and Development Labs.

2008-07-01

Establishment of materials technologies on piping and tubing for advanced ultra super critical (A-USC) plants operated at steam temperatures above 700 C is a critical issue to achieve its hard target. 23Cr-45Ni-7W alloy (HR6W) has been developed in Japan, originally as a high strength tubing material for 650 C USC boilers. In order to clarify the capability of HR6W as a material applied to A-USC plants, creep strength and microstructure of HR6W were investigated in comparison with {gamma}'-strengthened Alloy 617 and other Ni-base superalloys, such as Alloy 263. It has been revealed that the amount of added W is intimately correlated with precipitation amount of Laves phase and thus it is a crucial factor controlling creep strength. Stability of long term creep strength and superior creep rupture ductility have been proved by creep rupture tests at 650-800 C up to 60000h. The 10{sup 5}h extrapolated creep rupture strengths are estimated to be 88MPa at 700 C and 64MPa at 750 C. Microstructural stability closely related with long term creep strength and toughness has also been confirmed by microstructural observations after creep tests and aging. Creep rupture strength of Alloy 617 has been found to be much higher than that of HR6W at 700 and 750 C, while comparable at 800 C. A thermodynamic calculation along with microstructural observation indicates that the amount of Laves phase in HR6W gradually decreases with increasing temperature, while that of {gamma}' in Alloy 617 rapidly decreases with increasing temperature and {gamma}' almost dissolves at 800 C. This may lead to an abrupt drop in creep strength of Alloy 617 above 750 C. Alloy 263, in which more {gamma}' precipitates than Alloy 617, shows much higher creep strength. However, it is suggested that inhomogeneous creep deformation is enhanced compared with HR6W and Alloy 617. Capability of HR6W as a material for A-USC plants was discussed in terms of creep properties, microstructural stability and other

The effect of Zr on the microstructure and properties of Ti-35Nb-XZr alloy

Energy Technology Data Exchange (ETDEWEB)

Málek, Jaroslav, E-mail: malek@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 00 Prague-Zbraslav (Czech Republic); Czech Technical University in Prague, Faculty of Mechanical Engineering, Karlovo náměstí 13, 121 35 Praha 2 (Czech Republic); Hnilica, František, E-mail: hnilica@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 00 Prague-Zbraslav (Czech Republic); Veselý, Jaroslav, E-mail: vesely@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 00 Prague-Zbraslav (Czech Republic); Smola, Bohumil, E-mail: smola@met.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, KeKarlovu 5, 121 16 Prague 2 (Czech Republic); Kolařík, Kamil, E-mail: kamil.kolarik@email.cz [Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Trojanova 339/13, 120 00 Praha 2 (Czech Republic); Fojt, Jaroslav, E-mail: jaroslav.fojt@vscht.cz [Institute of Chemical Technology, Technická 5, 166 28 Prague (Czech Republic); Vlach, Martin, E-mail: martin.vlach@mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, KeKarlovu 5, 121 16 Prague 2 (Czech Republic); Kodetová, Veronika [Charles University in Prague, Faculty of Mathematics and Physics, KeKarlovu 5, 121 16 Prague 2 (Czech Republic)

2016-10-15

The demand for biomaterials with high strength, low modulus, excellent biocompatibility and good corrosion resistance has led to the development of new alloys. Zirconium is known as a biocompatible element that can be used for alloying in titanium alloys. The effect of Zr on the mechanical and structural properties of a titanium alloy is studied in this paper. Binary Ti-35Nb alloy has been alloyed with various amounts of Zr (2, 4, 6 or 8 wt%). The specimens were thermo-mechanically processed (hot forged, solution treated 850 °C/0.5 h/water quenched, cold swaged and finally aged (at 400 °C or 450 °C for various periods). Cold-swaged alloys possess tensile strength of about 800 MPa, along with a low Young's modulus (~50 GPa). The elongation of all the alloys is more than 12%. The hardness increased during 400 °C annealing up to 370 HV10. The addition of Zr stabilized the β-phase and supports recrystallization and recovery processes. Corrosion resistance was also increased by the addition of Zr.

Multiaxial creep of tubes of Alloy 800 and Alloy 617 at high temperature

International Nuclear Information System (INIS)

Penkalla, H.J.; Schubert, F.; Nickel, H.

1989-01-01

The deformation behaviour under multiaxial loading at temperature higher than 800 deg. C is strongly controlled by creep. For dimensioning and inelastic analysis the use of v. Mises theory and Norton's creep law for stationary creep are demonstrated for different combination of internal pressure and axial or torsional stress or strains. The experimental results are in satisfactory agreement with the theoretical predicted deformation behaviour if values for the coefficient k and n in Norton's creep law are used, which are close to the real creep resistance in the component. (author). 11 refs, 12 figs, 2 tabs

A novel high performance composite anode with in situ growth of Fe-Ni alloy nanoparticles for intermediate solid oxide fuel cells

International Nuclear Information System (INIS)

Li, Jingcheng; Yu, Yan; Yin, Yi-Mei; Zhou, Ning; Ma, Zi-Feng

2017-01-01

Highlights: • A composite anode with endogenous Fe-Ni alloy nanoparticles has been prepared. • The redox reversibility of the anode has been confirmed by XRD. • The E_a of H_2 oxidation at the anode is much smaller than that at Ni-YSZ anode. • A ScSZ supported cell achieves MPD of 0.71 Wcm"−"2 and R_p of 0.16 Ω cm"2 at 800 °C. • The single cell shows stable output during 105 h testing at 800 °C 0.7 V in wet H_2". - Abstract: A redox reversible composite anode with Fe-Ni alloy nanoparticles in situ growth on SrLaFeO_4-type and LaFeO_3-type oxide substrates has been prepared for intermediate temperature solid oxide fuel cell (IT-SOFC) by reducing perovskite precursor La_0_._4Sr_0_._6Fe_0_._7_5Ni_0_._1Nb_0_._1_5O_3_-_δ (LSFNNb) in wet H_2 at 900 °C for 1 h. The anode has shown an excellent electrochemical catalytic activity for oxidation of hydrogen with much smaller E_a (25.1 ∼ 68.9 kJ mol"−"1) than the value (>160 kJ mol"−"1) at Ni-YSZ anode. A scandium stabilized zirconia (ScSZ) electrolyte supported SOFC with the anode achieves maximum power densities of 0.71, 0.52, 0.35, and 0.21 W cm"−"2 at 800, 750, 700 and 650 °C, respectively in wet H_2 (3% H_2O), and the corresponding R_p of 0.16, 0.21, 0.35, and 0.60 Ω cm"2 under OCV. Moreover, the single cell shows stable power output during ∼105 h operation at 800 °C under 0.7 V in wet H_2 after a initial degradation, indicating that R-LSFNNb is an excellent candidate as anode of IT-SOFC.

Relaxation resistance of heat resisting alloys with cobalt

International Nuclear Information System (INIS)

Borzdyka, A.M.

1977-01-01

Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading

Phase diagram of the Fe-Sn-Zr system at 800 °C

International Nuclear Information System (INIS)

Nieva, N.; Corvalán, C.; Jiménez, M.J.; Gómez, A.; Arreguez, C.; Joubert, J.-M.; Arias, D.

2017-01-01

New experimental results on the Fe-Sn-Zr phase diagram at 800 °C are presented, particularly in the central, Fe rich and Sn rich regions of the Gibbs triangle. Seven ternary alloys were designed, produced and examined by different techniques: optical and scanning electron microscopy, semi-quantitative microanalysis, quantitative microanalysis and X-ray diffraction. The results of this work and previous experimental data were used to determine the phase diagram section at 800 °C which contains at least five ternary compounds: Fe 6 Sn 6 Zr, Y, X′, θ and C36. - Highlights: •A phase diagram of Fe-Sn-Zr system at 800 °C is proposed. •The isothermal section of Fe-Sn-Zr system at 800 °C and that at 900 °C determined previously allow reliable extrapolations at low temperatures. •The study at different temperatures (900 °C and 800 °C in this case) is highly desirable because it allows the separation between enthalpic and entropic effects in a future Calphad modelling.

Phase diagram of the Fe-Sn-Zr system at 800 °C

Energy Technology Data Exchange (ETDEWEB)

Nieva, N. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Corvalán, C., E-mail: corvalan@cnea.gov.ar [Gerencia de Materiales, Comisión Nacional de Energía Atómica Argentina (CNEA), Universidad Nacional de Tres de Febrero, Argentina, CONICET, Consejo Nacional de Ciencia y Técnica (Argentina); Jiménez, M.J. [IFISUR, CONICET, Departamento de Física, Universidad Nacional del Sur, Bahía Blanca (Argentina); Gómez, A. [Grupo LMFAE – PPFAE, Centro Atómico Ezeiza, Comisión Nacional de Energía Atómica (Argentina); Arreguez, C. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Joubert, J.-M. [Chimie Métallurgique des Terres Rares (CMTR), Institut de Chimie et des Matériaux Paris-Est (ICMPE), CNRS, Université Paris-Est Créteil, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Arias, D. [Instituto de Tecnología J. Sabato, Universidad Nacional de San Martín-CNEA (Argentina)

2017-04-15

New experimental results on the Fe-Sn-Zr phase diagram at 800 °C are presented, particularly in the central, Fe rich and Sn rich regions of the Gibbs triangle. Seven ternary alloys were designed, produced and examined by different techniques: optical and scanning electron microscopy, semi-quantitative microanalysis, quantitative microanalysis and X-ray diffraction. The results of this work and previous experimental data were used to determine the phase diagram section at 800 °C which contains at least five ternary compounds: Fe{sub 6}Sn{sub 6}Zr, Y, X′, θ and C36. - Highlights: •A phase diagram of Fe-Sn-Zr system at 800 °C is proposed. •The isothermal section of Fe-Sn-Zr system at 800 °C and that at 900 °C determined previously allow reliable extrapolations at low temperatures. •The study at different temperatures (900 °C and 800 °C in this case) is highly desirable because it allows the separation between enthalpic and entropic effects in a future Calphad modelling.

Effect of Al content on structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Yurchenko, N.Yu. [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Stepanov, N.D., E-mail: stepanov@bsu.edu.ru [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Shaysultanov, D.G. [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Tikhonovsky, M.A. [National Science Center “Kharkov Institute of Physics and Technology”, NAS of Ukraine, Kharkov, 61108 (Ukraine); Salishchev, G.A. [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation)

2016-11-15

In present study, structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys after arc melting and annealing at 1200 °C for 24 h are investigated. The CrNbTiVZr alloy is composed of body centered cubic (bcc) and C15 (face centered cubic) Laves phases while the Al{sub x}CrNbTiVZr (x = 0.25; 0.5; 1) alloys consist of bcc and two C14 (hexagonal close packed) Laves phases with different chemical compositions. Thermodynamic modeling predicts existence of two phases – bcc and C15 Laves phase and broadening of single bcc phase field due to Al addition. The density of the alloys decreases with the increase of Al content. The alloys are found to be extremely brittle at room temperature and 600 °C. The alloys have high strength at temperatures of 800–1000 °C. For example, yield strength at 800 °C increases from 440 MPa for the CrNbTiVZr alloy to 1250 MPa for the AlCrNbTiVZr alloy. The experimental phase composition of the Al{sub x}CrNbTiVZr alloys is compared with predicted equilibrium phases and the factors governing the transformation of C15 to C14 Laves phases due to Al addition to the CrNbTiVZr alloy analyzed. Specific properties of the alloys are compared with other high-entropy alloys and commercial Ni-based superalloys. - Highlights: •Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) alloys are arc melted and annealed at 1200 °C. •The CrNbTiVZr alloy has bcc and C15 Laves phases. •The Al-containing alloys are composed of bcc and two C14 Laves phases. •The alloys demonstrate high specific strength at temperatures of 800 °C and 1000 °C. •The strength of the alloys increases in proportion with increase of Al content.

Effect of Thermal Aging on the Corrosion Behavior of Wrought and Welded Alloy 22

International Nuclear Information System (INIS)

Rebak, R.B.; Edgecumbe Summers, T.S.; Lian, T.

2002-01-01

Alloy 22 (UNS N06022) is a candidate material for the external wall of the high level nuclear waste containers for the potential repository site at Yucca Mountain. In the mill-annealed (MA) condition, Alloy 22 is a single face centered cubic phase. When exposed to temperatures on the order of 600 C and above for times higher than 1 h, this alloy may develop secondary phases that are brittle and offer a lower corrosion resistance than the MA condition. The objective of this work was to age Alloy 22 at temperatures between 482 C and 800 C for times between 0.25 h and 3,000 h and to study the corrosion performance of the resulting material. Aging was carried out using wrought specimens as well as gas tungsten arc welded (GTAW) specimens. The corrosion performance was characterized using standard immersion tests in aggressive acidic solutions and electrochemical tests in multi-component solutions. Results show that, in general, in aggressive acidic solutions the corrosion rate increased as the aging temperature and aging time increased. However, in multi ionic environments that could be relevant to the potential Yucca Mountain site, the corrosion rate of aged material was the same as the corrosion rate of the MA material

Effects of pH and chloride concentration on pitting corrosion of AA6061 aluminum alloy

International Nuclear Information System (INIS)

Zaid, B.; Saidi, D.; Benzaid, A.; Hadji, S.

2008-01-01

Effects of pH solution and chloride (Cl - ) ion concentration on the corrosion behaviour of alloy AA6061 immersed in aqueous solutions of NaCl have been investigated using measurements of weight loss, potentiodynamic polarisation, linear polarisation, cyclic polarisation experiment combined with open circuit potential transient technique and optical or scanning electron microscopy. The corrosion behaviour of the AA6061 aluminum alloy was found to be dependant on the pH and chloride concentration [NaCl] of solution. In acidic or slightly neutral solutions, general and pitting corrosion occurred simultaneously. In contrast, exposure to alkaline solutions results in general corrosion. Experience revealed that the alloy AA6061 was susceptible to pitting corrosion in all chloride solution of concentration ranging between 0.003 wt% and 5.5 wt% NaCl and an increase in the chloride concentration slightly shifted both the pitting E pit and corrosion E cor potentials to more active values. In function of the conditions of treatment, the sheets of the alloy AA6061 undergo two types of localised corrosion process, leading to the formation of hemispherical and crystallographic pits. Polarisation resistance measurements in acidic (pH = 2) and alkaline chloride solutions (pH = 12) which are in good agreement with those of weight loss, show that the corrosion kinetic is minimised in slightly neutral solutions (pH = 6)

Microsegregation and homogenization in U-Nb alloy

International Nuclear Information System (INIS)

Leal, J. Fernando; Nogueira, R.A.; Ambrozio Filho, F.

1987-01-01

Microsegregation results in U-4 w t% Nb alloys casted in nonconsumable electrode arc furnace are presented. The microsegregation is studied qualitatively by optical microscopy and quantitatively by electron microprobe. The degreee of homogenetization has been measured after 800 0 C heat treatments. The times required for homogeneization of the alloys are also discussed. (author) [pt

Influence of pH on the chemical and structural properties of the oxide films formed on 316L stainless steel, alloy 600 and alloy 690 in high temperature aqueous environments

International Nuclear Information System (INIS)

Dupin, M.; Gosser, P.; Walls, M.G.; Rondot, B.; Pastol, J.L.

2002-01-01

The oxide films formed on 316L stainless steel, alloy 600 and alloy 690 at 320 deg C in high temperature aqueous environments of different pH have been examined by glow discharge optical spectroscopy, scanning electron microscopy, atomic force microscopy and capacitance measurements. The analytical study reveals that the films formed at pH 5 are mainly composed of chromium oxides. When the pH increases the chromium concentration decreases and those of the other two elements (Ni and Fe) tend to increase. The films formed at pH 5 on 316L stainless steel and alloy 600 are thick and powder-like. The film formed at the same pH on alloy 690 is thin and is composed of a compact protective inner layer and a less-compact outer layer formed by crystals of mixed iron-nickel-chromium oxides. The morphological appearance of the thick films and that of the thin films is very different. However, equivalent morphologies can be observed for the relatively thin duplex films formed at pH 8 and pH 9.5 on the 316L stainless steel and nickel-base alloys. The evolution of the chemical composition of the films is accompanied by important changes from the point of view of their semi-conductivity. (authors)

Phase transition of Ni-Mn-Ga alloy powders prepared by vibration ball milling

International Nuclear Information System (INIS)

Tian, B.; Chen, F.; Tong, Y.X.; Li, L.; Zheng, Y.F.; Liu, Y.; Li, Q.Z.

2011-01-01

Research highlights: → The vibration ball milling with a high milling energy introduces the atomic disorder and large lattice distortion in the alloy during milling and makes the formation of disordered fcc structure phase in the alloy. → The transition temperature and activation energy for disordered fcc → disordered bcc are ∼320 o C and 209 ± 8 kJ/mol, respectively. → The alloy powders annealed at 800 o C for 1 h show a one-stage martensitic transformation with quite lower latent heat compared to the bulk alloy. - Abstract: This study investigated the phase transformation of the flaky shaped Ni-Mn-Ga powder particles with thickness around 1 μm prepared by vibration ball milling and post-annealing. The SEM, XRD, DSC and ac magnetic susceptibility measurement techniques were used to characterize the Ni-Mn-Ga powders. The structural transition of Heusler → disordered fcc occurred in the powders prepared by vibration ball milling (high milling energy) for 4 h, which was different from the structural transition of Heusler → disordered fct of the powders fabricated by planetary ball milling (low milling energy) for 4 h. The two different structures after ball milling should be due to the larger lattice distortion occurred in the vibration ball milling process than in the planetary ball milling process. The structural transition of disordered fcc → disordered bcc took place at ∼320 o C during heating the as-milled Ni-Mn-Ga powders, which was attributed to the elimination of lattice distortion caused by ball milling. The activation energy for this transition was 209 ± 8 kJ/mol. The Ni-Mn-Ga powder annealed at 800 o C mainly contained Heusler austenite phase at room temperature and showed a low volume of martensitic transformation upon cooling. The inhibition of martensitic transformation might be attributed to the reduction of grain size in the annealed Ni-Mn-Ga particles.

Oxidation performance of a Fe-13Cr alloy with additions of rare earth elements

International Nuclear Information System (INIS)

Martinez-Villafane, A.; Chacon-Nava, J.G.; Gaona-Tiburcio, C.; Almeraya-Calderon, F.; Dominguez-Patino, G.; Gonzalez-Rodriguez, J.G.

2003-01-01

The influence of rare earth elements (REE's) i.e. Neodymium (Nd) and Praseodymium (Pr) on the oxidation behavior of a Fe-13Cr alloy has been studied, and its role on the oxidation rate and oxide morphology and formation is discussed. Specimens were isothermally oxidized in oxygen at 800 deg. C for 24 h. It was found that a small addition (≤0.03 wt.%) of either Nd or Pr, reduced the oxidation rate of the Fe-13Cr base alloy. Moreover, the simultaneous addition of both elements to the alloy produced a dramatic reduction in the oxidation kinetics. Analysis by scanning electronic microscope (SEM) revealed that the morphology of oxides formed on Fe-13Cr specimens with and without REE's specimens was very different. In fact, a fine-grained oxide morphology was observed for alloys with REE's addition. For these alloys only, chromium enrichment at the metal/scale interface was observed. From transmission electronic microscope (TEM) analysis, it was found the following: at the early stages of oxide formation, after 0.25 h, Cr 2 O 3 , Fe 3 O 4 , α-Fe 2 O 3 and γ-Fe 2 O 3 were formed; at 6 h, Cr 2 O 3 , FeCr 2 O 4 and α-Fe 2 O 3 were identified and, for exposure times greater than 6 h, Cr 2 O 3 , α-Fe 2 O 3 and a spinel which was presumably transformed into a solid solution (Fe 2 O 3 ·Cr 2 O 3 ) were found

The THIRST chemistry module as a tool to determine optimal steam generator corrosion control strategies

International Nuclear Information System (INIS)

Heppner, K.; Laroche, S.; Pietralik, J.

2006-01-01

As part of a coordinated program, AECL is developing a set of tools to aid with the prediction and management of steam generator performance. Although stress corrosion cracking (of Alloy 800) has not been detected in any operating steam generator, for life management it is necessary to develop mechanistic models to predict the conditions under which stress corrosion cracking is plausible. Therefore, constant extension rate tests were carried out for Alloy 800 under various steam generator crevice chemistry conditions at applied potentials. These tests were designed to evaluate the stress corrosion cracking susceptibility of Alloy 800 under CANDU( steam generator operating conditions. Based on the experimental results, the recommended electrochemical corrosion potential/pH zone for Alloy 800 determined by electrochemical polarization measurements was verified with the respect of stress corrosion cracking susceptibility. The effects of lead contamination on the stress corrosion cracking susceptibility of Alloy 800 tubing were also evaluated. The experimental results from constant extension rate tests obtained under applied potentials suggest that Alloy 800 has good performance inside much of a previously recommended electrochemical corrosion potential/pH zone determined by electrochemical analysis. Alloy 800 is not susceptible to stress corrosion cracking under normal CANDU steam generator operating conditions. However, Alloy 800 may be susceptible to stress corrosion cracking under near-neutral crevice chemistry conditions in the presence of oxidants. In addition, stress corrosion cracking susceptibility is increased by lead contamination. This observation suggests that the previously defined electrochemical corrosion potential limit under near-neutral crevice conditions could be modified to minimize stress corrosion cracking of Alloy 800. The test results from this work also suggest that the pH dependency of the stress corrosion cracking susceptibility of Alloy 800

Electrochemical properties in a seawater environment of 5456-H116 aluminum alloy subjected to optimal friction stir processing

International Nuclear Information System (INIS)

Park, Jae-Cheul; Kim, Seong-Jong

2010-01-01

The mechanical properties of aluminum alloy may be enhanced by modifying the microstructure of the metal by friction stir processing (FSP). Previous studies have demonstrated that the mechanical characteristics of 5456-H116 Al alloy subjected to FSP, at 250 rpm and 15 mm min -1 using a full screw probe, are similar to those of the original alloy. In the present work, the same alloy was processed under these optimal conditions, and the range of favorable protection potentials with regard to hydrogen embrittlement and stress corrosion cracking was determined to lie between -1.3 and -0.7 V (versus Ag/AgCl). The electrochemical behavior of the specimens subjected to FSP was superior to that of the original 5456-H116 Al alloy.

Electrochemical properties in a seawater environment of 5456-H116 aluminum alloy subjected to optimal friction stir processing

Science.gov (United States)

Park, Jae-Cheul; Kim, Seong-Jong

2010-05-01

The mechanical properties of aluminum alloy may be enhanced by modifying the microstructure of the metal by friction stir processing (FSP). Previous studies have demonstrated that the mechanical characteristics of 5456-H116 Al alloy subjected to FSP, at 250 rpm and 15 mm min-1 using a full screw probe, are similar to those of the original alloy. In the present work, the same alloy was processed under these optimal conditions, and the range of favorable protection potentials with regard to hydrogen embrittlement and stress corrosion cracking was determined to lie between -1.3 and -0.7 V (versus Ag/AgCl). The electrochemical behavior of the specimens subjected to FSP was superior to that of the original 5456-H116 Al alloy.

Optical characteristics of jewellery gold alloys

International Nuclear Information System (INIS)

Wan Mahmood bin Mat Yunus; Zainal Abidin bin Talib; Maarof bin Moksin; Abdul Fatah bin Awang Mat

1994-01-01

Measurements of the reflection of various sample of gold alloys were made over the wavelength range 400-800 nm. Samples were measured using a single beam spectrophotometer at 45 deg. angle of incidence. In this measurement no attempt was made to obtain the optical constants of the samples. The results showed that there were significant differences between bulk and thick samples, with sufficient spectra difference between different composition of the alloys

Thermophysical properties of Alloy 617 from 25 °C to 1000 °C

International Nuclear Information System (INIS)

Rabin, B.H.; Swank, W.D.; Wright, R.N.

2013-01-01

Highlights: • Thermophysical properties of Alloy 617 have been measured to 1000 °C. • Thermal conductivity at 600–850 °C is nonlinear due to Ni–Cr short-range ordering. • Four different heats and long-term aged material all exhibited similar properties. -- Abstract: Key thermophysical properties needed for the successful design and use of Alloy 617 in steam generator and heat exchanger applications have been measured experimentally, and results are compared with literature values and results obtained from some other commercial Ni–Cr alloys and model materials. Specifically, the thermal diffusivity, thermal expansion coefficient, and specific heat capacity have been measured for Alloy 617 over a range of temperatures, allowing calculation of thermal conductivity up to 1000 °C. It has been found that the thermal conductivity of Alloy 617 exhibits significant deviation from monotonic behavior in the temperature range from 600 °C to 850 °C, the temperatures of interest for most heat transfer applications. The non-linear behavior appears to result primarily from short-range order/disorder phenomena known to occur in the Ni–Cr system. Similar deviation from monotonic behavior was observed in the solid solution Ni–Cr-W Alloy 230, and lesser deviations were observed in iron based Alloy 800H and an austenitic stainless steel. Measured thermophysical property data are provided for four different heats of Alloy 617, and it is shown that property variations between the four different heats are not significant. Measurements were also obtained from Alloy 617 that was aged for up to 2000 h at 750 °C, and it was found that this aging treatment does not significantly influence the thermophysical properties

Ab initio investigation of the surface properties of austenitic Fe-Ni-Cr alloys in aqueous environments

Energy Technology Data Exchange (ETDEWEB)

Rák, Zs., E-mail: zrak@ncsu.edu; Brenner, D.W.

2017-04-30

Highlights: • The trend in the surface energies of austenitic stainless steels is: (111) < (100) < (110). • On the (111) orientation Ni segregates to the surface and Cr segregates into the bulk. • The surface stability of the alloys in contact with water decrease with temperature and pH. - Abstract: The surface energetics of two austenitic stainless steel alloys (Type 304 and 316) and three Ni-based alloys (Alloy 600, 690, and 800) are investigated using theoretical methods within the density functional theory. The relative stability of the low index surfaces display the same trend for all alloys; the most closely packed orientation and the most stable is the (111), followed by the (100) and the (110) surfaces. Calculations on the (111) surfaces using various surface chemical and magnetic configurations reveal that Ni has the tendency to segregate toward the surface and Cr has the tendency to segregate toward the bulk. The magnetic frustration present on the (111) surfaces plays an important role in the observed segregation tendencies of Ni and Cr. The stability of the (111) surfaces in contact with aqueous solution are evaluated as a function of temperature, pH, and concentration of aqueous species. The results indicate that the surface stability of the alloys decrease with temperature and pH, and increase slightly with concentration. Under conditions characteristic to an operating pressurized water reactor, the Ni-based alloy series appears to be of better quality than the stainless steel series with respect to corrosion resistance and release of aqueous species when in contact with aqueous solutions.

A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

International Nuclear Information System (INIS)

Krause, T. W.; Babbar, V. K.; Underhill, P. R.

2014-01-01

Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators

A pulsed eddy current probe for inspection of support plates from within Alloy-800 steam generator tubes

Science.gov (United States)

Krause, T. W.; Babbar, V. K.; Underhill, P. R.

2014-02-01

Support plate degradation and fouling in nuclear steam generators (SGs) can lead to SG tube corrosion and loss of efficiency. Inspection and monitoring of these conditions can be integrated with preventive maintenance programs, thereby advancing station-life management processes. A prototype pulsed eddy current (PEC) probe, targeting inspection issues associated with SG tubes in SS410 tube support plate structures, has been developed using commercial finite element (FE) software. FE modeling was used to identify appropriate driver and pickup coil configurations for optimum sensitivity to changes in gap and offset for Alloy-800 SG tubes passing through 25 mm thick SS410 support plates. Experimental measurements using a probe that was manufactured based on the modeled configuration, were used to confirm the sensitivity of differential PEC signals to changes in relative position of the tube within the tube support plate holes. Models investigated the effect of shift and tilt of tube with respect to hole centers. Near hole centers and for small shifts, modeled signal amplitudes from the differentially connected coil pairs were observed to change linearly with tube shift. This was in agreement with experimentally measured TEC coil response. The work paves the way for development of a system targeting the inspection and evaluation of support plate structures in steam generators.

Corrosion characteristics of an aluminium alloy in the H3PO4 - CO2 mixture

International Nuclear Information System (INIS)

Aljinovic, Lj.; Smith, M.; Gotovac, V.

1998-01-01

The Al 6063 alloy examined in this work contains silicon and magnesium capable of forming Mg 2 Si and iron, which can form an intermetallic second phase (FeAl 3 ). In order to examine the influence of temperature on the corrosion behaviour of the Al 6063 alloy, examinations were carried out in aerated H 3 PO 4 and in H 3 PO 4 saturated with CO 2 at temperatures of 20, 30, 40, and 50 C. The following electrochemical methods were applied: determination of dependence of E OCP on time, recording of anodic and cathodic polarization curves, and cyclic voltammetry. It has been observed that corrosion parameters obtained are strongly temperature dependent. They also depend on CO 2 dissolved in H 3 PO 4 . CO 2 retards cathodic and anodic reactions at all temperatures, which can be attributed to formation of a kind of mechanical passivity as alloy components react with CO 2 . (orig.)

The structural-phenomenological description of plastic anisotropy of H-1 and H-2.5 alloys, subjected to reactors irradiation

International Nuclear Information System (INIS)

Yamshchikov, N.V.; Prasolov, P.F.; Lebedinskij, K.B.

1990-01-01

The structural-phenomenological model of anisotropic single hpc textured polycrystals is described. The formulation of the present model is assumed that the polycrystal is continuous three-dimensional collection of transversal crystallites, the plastic properties which Hill's yield criteria are described. This model is allowed to determine six parameters in the Hill's yield criteria for ortho tropic materials based on only of uniaxial tension test in three directions and crystallographic texture. Yield surfaces of zircaloy alloys at 293 K and 623 K, subjected to irradiation in the reactor with total exposition dose 10 20 n/cm 2 are determined. Strongly influence of irradiation on the plastic behaviour of H-1 and H-2,5 alloys is observed. 2 refs.; 3 figs.; 2 tables. (author)

A Comparative Analysis of the Corrosive Effect of Artificial Saliva of Variable pH on DMLS and Cast Co-Cr-Mo Dental Alloy.

Science.gov (United States)

Puskar, Tatjana; Jevremovic, Danimir; Williams, Robert J; Eggbeer, Dominic; Vukelic, Djordje; Budak, Igor

2014-09-11

Dental alloys for direct metal laser sintering (DMLS) are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM) samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-MS). The obtained results show that the metal elution in artificial saliva from the DMLS alloy was lower than the elution from the CM alloy. The release of all investigated metal ions was influenced by the acidity, both from the DMLS and CM alloy, throughout the investigated period of 30 days. The change in acidity from a pH of 6.8 to a pH of 2.3 for the cast alloy led to a higher increase of the elution of Co, Cr and Mo from CM than from the DMLS alloy. The greatest release out of Co, Cr and Mo was for Co for both tested alloys. Further, the greatest release of all ions was measured at pH 2.3. In saliva of pH 2.3 and pH 4.5, the longer the investigated period, the higher the difference between the total metal ion release from the CM and DMLS alloys. Both alloys showed a safe level of elution according to the ISO definition in all investigated acidic environments.

A Comparative Analysis of the Corrosive Effect of Artificial Saliva of Variable pH on DMLS and Cast Co-Cr-Mo Dental Alloy

Directory of Open Access Journals (Sweden)

Tatjana Puskar

2014-09-01

Full Text Available Dental alloys for direct metal laser sintering (DMLS are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-MS. The obtained results show that the metal elution in artificial saliva from the DMLS alloy was lower than the elution from the CM alloy. The release of all investigated metal ions was influenced by the acidity, both from the DMLS and CM alloy, throughout the investigated period of 30 days. The change in acidity from a pH of 6.8 to a pH of 2.3 for the cast alloy led to a higher increase of the elution of Co, Cr and Mo from CM than from the DMLS alloy. The greatest release out of Co, Cr and Mo was for Co for both tested alloys. Further, the greatest release of all ions was measured at pH 2.3. In saliva of pH 2.3 and pH 4.5, the longer the investigated period, the higher the difference between the total metal ion release from the CM and DMLS alloys. Both alloys showed a safe level of elution according to the ISO definition in all investigated acidic environments.

High temperature oxidation and electrochemical investigations on nickel-base alloys

International Nuclear Information System (INIS)

Obigodi-Ndjeng, Georgia

2011-01-01

This study examined high-temperature oxidation behavior of different Ni-base alloys. In addition, electrochemical characterization of the alloy's corrosion behavior was carried out, including comparison of the properties of native passive films grown at room temperature and high temperature oxide scales. PWA 1483 (single-crystalline Ni-base superalloy) and model alloys Ni-Cr-X (where X is either Co or Al) were oxidized at 800 and 900 C in air for different time periods. The superalloy showed the best oxidation behavior at both temperatures, which might be due to the fact that the oxidation growth function is subparabolic for the model alloys and parabolic for the superalloy at 800 C. At higher temperatures, changes in the kinetics are induced, as the oxides grow faster, thus only PWA 1483 growth follows the parabolic law. Different scales in a typical sandwich form were detected, with the inner layer comprised of mostly Cr 2 O 3 , the middle layer was mixture of different oxides and spinels, depending on the alloying elements, and the oxide at the interface oxygen/oxide was found to be NiO. The influence of sample preparation could also be shown, as rougher surfaces change the oxidation kinetics from parabolic and subparabolic for polished samples to linear. The influence of moisture on the oxidation behavior of the 2 nd generation single crystal Ni-base superalloys (PWA 1484, PWA 1487, CMSX 4, Rene N5 and Rene N5+) was studied at 1000 C after 100 h oxidation period. It was found that the moisture increased the oxidation rate and mostly the transient oxides growth rate. The water vapor content in air also influenced the behavior of these alloys, as they showed a higher mass gain in air + 30% water vapor than in air + 10% water vapor. The alloys PWA 1484 and CMSX 4 showed respectively the worst and best behavior in all the studied atmospheres. The addition of reactive elements, such as Yttrium, Hafnium and Lanthanum is likely to enhance the oxidation behavior of PWA

Magnetic properties of nanocrystalline Fe–10%Ni alloy obtained by planetary ball mills

International Nuclear Information System (INIS)

Hamzaoui, Rabah; Elkedim, Omar

2013-01-01

Highlights: •Solid solution formation accompanied by a grain refinement for nanocrystalline Fe-Ni. •The shock mode process (SMP) prevails when Ω > >ω. •The friction mode process (FMP) is stronger when Ω < <ω. •The FMP leads to the formation of alloys exhibiting a soft magnetic behavior. -- Abstract: Planetary ball mill PM 400 from Retsch (with different milling times for Ω = 400 rpm, ω = 800 rpm) and P4 vario ball mill from Fritsch (with different milling conditions (Ω/ω), Ω and ω being the disc and the vial rotation speeds, respectively) are used for obtaining nanocrystalline Fe–10wt% Ni. The structure and magnetic properties are studied by using X-ray diffraction, SEM and hysteresis measurements, respectively. The bcc-Fe(Ni) phase formation is identified by X-ray diffraction. The higher the shock power and the higher milling time are, the larger the bcc lattice parameter and the lower the grain size. The highest value of the coercivity is 1600 A/m for Fe–10 wt.%Ni (with shock mode (424 rpm/100 rpm) after 36 h of milling), while the lowest value is 189 A/m for (400 rpm/800 rpm) after 72 h of milling. The milling performed in the friction mode has been found to lead the formation of alloys exhibiting a soft magnetic behavior for nanocrystalline Fe–10%Ni

Grain refinement of an AZ63B magnesium alloy by an Al-1C master alloy

Energy Technology Data Exchange (ETDEWEB)

Yichuan Pan; Xiangfa Liu; Hua Yang [The Key Lab. of Liquid Structure and Heredity of Materials, Shandong Univ., Jinan (China)

2005-12-01

In order to develop a refiner of Mg-Al alloys, an Al-1C (in wt.%) master alloy was synthesized using a casting method. The microstructure and grain-refining performance of the Al-1C master alloy were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and a grain-refining test. The microstructure of the Al-1C master alloy is composed of {alpha}-Al solid solution, Al{sub 4}C{sub 3} particles, and graphite phases. After grain refinement of AZ63B alloy by the Al-1C master alloy, the mean grain size reached a limit when 2 wt.% Al-C master alloy was added at 800 C and held for 20 min in the melt before casting. The minimum mean grain size is approximately 48 {mu}m at the one-half radius of the ingot and is about 17% of that of the unrefined alloy. The Al-1C master alloy results in better grain refinement than C{sub 2}Cl{sub 6} and MgCO{sub 3} carbon-containing refiners. (orig.)

Out-of-pile chemical compatibility of Pb-Bi eutectic alloy with graphite

Energy Technology Data Exchange (ETDEWEB)

Sengupta, A.K.; Bhagat, R.K.; Jarvis, T.; Majumdar, S. [Radiometallurgy Div., Bhabha Atomic Research Centre, Mumbai (India); Laik, A.; Kale, G.B. [Material Science Div., Bhabha Atomic Research Centre, Mumbai (India); Kamath, H.S. [Nuclear Fuels Group, Bhabha Atomic Research Centre, Mumbai (India)

2006-06-15

Lead Bismuth eutectic alloy (Pb: 55.5 wt.%, Bi: 44.5 wt.%) is a potential candidate coolant material for high-temperature reactors because of its low melting point (124 C), high thermal conductivity, heat capacity, and better neutronic properties. Out-of-pile chemical compatibility studies of this coolant with graphite (coolant channel) have been carried out by isothermal annealing of the liquid alloy in a graphite crucible at 800, 900, 1000, and 1100 C for times ranging from 100 h to 1000 h. Formation of a reaction layer is observed. The growth rate of the reaction layer follows a parabolic law. Reaction layer thicknesses of 61.3 {mu}m and 121 {mu}m are estimated from the growth rate vs. time relation after 1 year and 5 years respectively. The growth of the reaction layer is diffusion-controlled and the activation energy of the reaction is estimated to be 100 KJ/mol. (orig.)

Out-of-pile chemical compatibility of Pb-Bi eutectic alloy with graphite

International Nuclear Information System (INIS)

Sengupta, A.K.; Bhagat, R.K.; Jarvis, T.; Majumdar, S.; Laik, A.; Kale, G.B.; Kamath, H.S.

2006-01-01

Lead Bismuth eutectic alloy (Pb: 55.5 wt.%, Bi: 44.5 wt.%) is a potential candidate coolant material for high-temperature reactors because of its low melting point (124 C), high thermal conductivity, heat capacity, and better neutronic properties. Out-of-pile chemical compatibility studies of this coolant with graphite (coolant channel) have been carried out by isothermal annealing of the liquid alloy in a graphite crucible at 800, 900, 1000, and 1100 C for times ranging from 100 h to 1000 h. Formation of a reaction layer is observed. The growth rate of the reaction layer follows a parabolic law. Reaction layer thicknesses of 61.3 μm and 121 μm are estimated from the growth rate vs. time relation after 1 year and 5 years respectively. The growth of the reaction layer is diffusion-controlled and the activation energy of the reaction is estimated to be 100 KJ/mol. (orig.)

The quasicrystalline phase formation in Al-Cu-Cr alloys produced by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Sviridova, T.A.; Shevchukov, A.P.; Shelekhov, E.V. [National University of Science and Technology ' MISIS' , Moscow 119049 (Russian Federation); Diakonov, D.L. [Bardin Central Research Institute for the Iron and Steel Industry, Moscow 105005 (Russian Federation); Tcherdyntsev, V.V.; Kaloshkin, S.D. [National University of Science and Technology ' MISIS' , Moscow 119049 (Russian Federation)

2011-06-15

Research highlights: > Formation of decagonal quasicrystalline phase in Al-Cu-Cr alloys. > Obtained decagonal phase belongs to D{sub 3} family of decagonal quasicrystals. > Decagonal phase has 1.26 nm periodicity along 10-fold axis. > Alloys were produced by combination of mechanical alloying and subsequent annealing. > Phase composition of as-milled powders depending on annealing temperature. - Abstract: Almost single-phase decagonal quasicrystal with periodicity of 1.26 nm along 10-fold axis was produced in Al{sub 69}Cu{sub 21}Cr{sub 10} and Al{sub 72.5}Cu{sub 16.5}Cr{sub 11} alloys using combination of mechanical alloying (MA) and subsequent annealing. Phase transformations of as-milled powders depending on annealing temperature in the range of 200-800 deg. C are examined. Since the transformations can be explained based on kinetic and thermodynamic reasons it seems that applied technique (short preliminary MA followed by the annealing) permits to produce the equilibrium phases rather than metastable ones.

Corrosion tests of high temperature alloys in impure helium

International Nuclear Information System (INIS)

Berka, Jan; Kalivodova, Jana; Vilemova, Monika; Skoumalova, Zuzana; Brabec, Petr

2014-01-01

Czech research organizations take part several projects concerning technologies and materials for advanced gas cooled reactors, as an example international project ARCHER supported by EU within FP7, also several national projects supported by Technology Agency of the Czech Republic are solved in cooperation with industrial and research organization. Within these projects the material testing program is performed. The results presented in these paper concerning high temperature corrosion and degradation of alloys (800 H, SS 316 and P91) in helium containing minor impurities (H_2, CO, CH_4, HZO) at temperatures up to 760°C. After corrosion tests (up to 1500 hours) the specimens was investigated by several methods (gravimetry, SEM-EDX, optical microscopy, hardness and micro-hardness testing etc. (author)

Microstructure, martensitic transformation, mechanical and shape memory properties of Ni–Co–Mn–In high-temperature shape memory alloys under different heat treatments

International Nuclear Information System (INIS)

Yang, Shuiyuan; Wang, Cuiping; Shi, Zhan; Wang, Jinming; Zhang, Jinbin; Huang, Yixiong; Liu, Xingjun

2016-01-01

The microstructure, martensitic transformation behavior, mechanical and shape memory properties of Ni 40 Co 10 Mn 41+x In 9−x (x=0, 2 and 4) high-temperature shape memory alloys annealed at 900 °C for 24 h or at 800 °C for 2 h were investigated, respectively. The tetragonal martensite phase and fcc γ phase are observed in all the studied alloys. The reversible martensitic transformation temperatures of the alloys increase with the increases of the electron concentration and the tetragonality of martensite phase. The amount of γ phase gradually increases with the decrease of In content, and much more γ phase in the alloys annealed at 900 °C results in slightly larger compressive fracture strain. Although the alloys with x=0 and 2 have a mass of γ phase, they still exhibit good shape memory properties. The amount of γ phase reaches about 20% in the alloy with x=0 after annealed at 900 °C, but a full recovery strain of 3.6% and a two-way shape memory effect of 0.8% can be obtained after two thermomechanical cycles.

Isothermal equilibrium pressures of Y-Th alloy-H2 system

International Nuclear Information System (INIS)

Tanase, M.; Fisher, P.W.

1985-01-01

Isothermal equilibrium pressures of the Y 4 Th (3:2 by weight) alloy-H 2 system were measured as a function of atomic composition [H]/[Y + Th] in the temperature range 580-1160 K. The isotherms have two plateaux in the pressure range 10 -2 -10 3 Pa. The first plateau region is attributed to the formation of YH 2 , and the equilibrium pressure P in pascals was found to be log P = 12.36 - 11300/T where T is in kelvins. The second plateau is attributed to the formation of ThH 2 , and the equilibrium pressure was found to be log P = 10.66 - 6891/T. In low atomic composition region the system obeys Sieverts' law. (Auth.)

Development of Fe-Ni and Ni-base alloys without {gamma}' strengthening for advanced USC boilers

Energy Technology Data Exchange (ETDEWEB)

Semba, Hiroyuki; Okada, Hirokazu; Igarashi, Masaaki; Hirata, Hiroyuki [Sumitomo Metal Industries, Ltd., Amagasaki, Hyogo (Japan). Corporate Research and Development Labs.; Yoshizawa, Mitsuru [Sumitomo Metal Industries Ltd., Amagasaki, Hyogo (Japan). Steel Tube Works

2010-07-01

An Fe-Ni base alloy, 23Cr-45Ni-7W alloy (HR6W) strengthened by Fe{sub 2}W-type Laves phase is one of the candidate materials for the piping application. Stability of long-term creep strength and superior creep rupture ductility have been proved by creep rupture tests up to 60000h at 650-800 C. The 10{sup 5}h extrapolated creep rupture strength at 700 C approved by TUV is 85MPa. It has also been confirmed that HR6W has excellent microstructural stability by means of microstructural observations after term creep tests and aging. A thick wall pipe of HR6W, which is 457mm in diameter and 60mm in wall thickness, has successfully been manufactured by the Erhart Push Bench press method. This trial production has shown that hot workability of HR6W is sufficient for manufacturing thick wall piping for A-USC plants. A new Ni-base alloy, 30r-50Ni-4W alloy (HR35) has been proposed for piping application having comparable creep rupture strength with Alloy 617 at 700 C. This alloy is not strengthened by {gamma}' phase but mainly by {alpha}-Cr phase. The 10{sup 5}h extrapolated creep rupture strength is estimated to be 114 MPa at 700 C. It has sufficient creep rupture ductility compared with Alloy 617. A thick wall pipe of HR35 has also been successfully manufactured. Capability of HR6W and HR35 as structural materials for A-USC plants has been examined in detail. They have high resistance to relaxation cracking after welding. It is, therefore, concluded that both the alloys are promising candidates especially for thick wall piping in A-USC power plants. (orig.)

Evaluation of High Temperature Corrosion Resistance of Finned Tubes Made of Austenitic Steel And Nickel Alloys

Directory of Open Access Journals (Sweden)

Turowska A.

2016-06-01

Full Text Available The purpose of the paper was to evaluate the resistance to high temperature corrosion of laser welded joints of finned tubes made of austenitic steel (304,304H and nickel alloys (Inconel 600, Inconel 625. The scope of the paper covered the performance of corrosion resistance tests in the atmosphere of simulated exhaust gases of the following chemical composition: 0.2% HCl, 0.08% SO2, 9.0% O2 and N2 in the temperature of 800°C for 1000 hours. One found out that both tubes made of austenitic steel and those made of nickel alloy displayed good resistance to corrosion and could be applied in the energy industry.

Tensile properties of several 800 MeV proton-irradiated bcc metals and alloys

International Nuclear Information System (INIS)

Brown, R.D.; Wechsler, M.S.; Tschalar, C.

1987-01-01

A spallation neutron source for the 600-MeV proton accelerator facility at the Swiss Institute for Nuclear Research (SIN) consists of a vertical cylinder filled with molten Pb-Bi. The proton beam enters the cylinder, passing upward through a window in contact with the Pb-Bi eutectic liquid that must retain reasonable strength and ductility upon irradiation at about 673 K to fluence of about 1 x 10/sup 25/ protons/m/sup 2/. Investigations are underway at the 800-MeV proton accelerator at the Los Alamos Meson Physics Facility (LAMPF) to test the performance of candidate SIN window materials under appropriate conditions of temperature, irradiation, and environment. Based on considerations of chemical compatibility with molten Pb-Bi, as well as interest in identifying fundamental radiation damage mechanisms, Fe, Ta, Fe-2.25Cr-1Mo, and Fe-12Cr-1Mo(HT-9) were chosen as candidate materials. Sheet tensile samples, 0.5-mm thick, of the four materials were fabricated and heat treated. The samples were sealed inside capsules containing Pb-Bi and were proton-irradiated at LAMPF to two fluences, 4.8 and 54 x 10/sup 23/ p/m/sup 2/. The beam current was approximately equal to the 1 mA anticipated for the upgraded SIN accelerator. The power deposited by the proton beam in the capsules was sufficient to maintain sample temperatures of about 673 K. Post-irradiation tensile tests were conducted at room temperature at a strain rate of 9 x 10/sup -4/s/sup -1/. The yield and ultimate strengths increased upon irradiation in all materials, while the ductility decreased, as indicated by the uniform strain. The pure metals, Ta and Fe, exhibited the greatest radiation hardening and embrittlement. The HT-9 alloy showed the smallest changes in strength and ductility. The increase in strength following irradiation is discussed in terms of a dispersed-barrier hardening model, for which the barrier sizes and formation cross sections are calculated

Thermal Analysis in the Technological “Step” Test of H282 Nickel Alloy

Directory of Open Access Journals (Sweden)

Pirowski Z.

2015-03-01

Full Text Available Superalloys show a good combination of mechanical strength and resistance to surface degradation under the influence of chemically active environments at high temperature. They are characterized by very high heat and creep resistance. Their main application is in gas turbines, chemical industry, and in all those cases where resistance to creep and the aggressive corrosion environment is required. Modern jet engines could never come into use if not for progress in the development of superalloys. Superalloys are based on iron, nickel and cobalt. The most common and the most interesting group includes superalloys based on nickel. They carry loads at temperatures well in excess of the eighty percent of the melting point. This group includes the H282 alloy, whose nominal chemical composition is as follows (wt%: Ni - base, Fe - max. 1.5%, Al - 1.5% Ti - 2.1%, C - 0.06% Co - 10% Cr - 20% Mo - 8.5%. This study shows the results of thermal analysis of the H282 alloy performed on a cast step block with different wall thickness. Using the results of measurements, changes in the temperature of H282 alloy during its solidification were determined, and the relationship dT / dt = f (t was derived. The results of the measurements taken at different points in the cast step block allowed identifying a number of thermal characteristics of the investigated alloy and linking the size of the dendrites formed in a metal matrix (DAS with the thermal effect of solidification. It was found that the time of solidification prolonged from less than ome minute at 10 mm wall thickness to over seven minutes at the wall thickness of 44 mm doubled the value of DAS.

Study of Dissimilar Welding AA6061 Aluminium Alloy and AZ31B Magnesium Alloy with ER5356 Filler Using Friction Stir Welding

Science.gov (United States)

Mahamud, M. I. I.; Ishak, M.; Halil, A. M.

2017-09-01

This paper is to study of dissimilar welding AA6061 aluminium alloy and AZ31B magnesium alloy with ER5356 filler using friction stir welding. 2 mm thick plates of aluminium and magnesium were used. Friction stir welding operations were performed at different rotation and travel speeds and used the fixed tilt angle which is 3°. The rotation speeds varied from 800 to 1100 rpm, and the travel speed varied from 80 to 100 mm/min. In the range rotation speed of 800 to 1000 rpm and welding speed of 80 to 100 mm/min there are no defect at the weld. Tensile test show the higher tensile strength is 198 MPa and the welding efficiency is about 76%.

Burner rig alkali salt corrosion of several high temperature alloys

Science.gov (United States)

Deadmore, D. L.; Lowell, C. E.

1977-01-01

The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

Osteoblast Cell Response on the Ti6Al4V Alloy Heat-Treated

Directory of Open Access Journals (Sweden)

Mercedes Paulina Chávez-Díaz

2017-04-01

Full Text Available In an effort to examine the effect of the microstructural changes of the Ti6Al4V alloy, two heat treatments were carried out below (Ti6Al4V800 and above (Ti6Al4V1050 its β-phase transformation temperature. After each treatment, globular and lamellar microstructures were obtained. Saos-2 pre-osteoblast human osteosarcoma cells were seeded onto Ti6Al4V alloy disks and immersed in cell culture for 7 days. Electrochemical assays in situ were performed using OCP and EIS measurements. Impedance data show a passive behavior for the three Ti6Al4V alloys; additionally, enhanced impedance values were recorded for Ti6Al4V800 and Ti6Al4V1050 alloys. This passive behavior in culture medium is mostly due to the formation of TiO2 during their sterilization. Biocompatibility and cell adhesion were characterized using the SEM technique; Ti6Al4V as received and Ti6Al4V800 alloys exhibited polygonal and elongated morphology, whereas Ti6Al4V1050 alloy displayed a spherical morphology. Ti and O elements were identified by EDX analysis due to the TiO2 and signals of C, N and O, related to the formation of organic compounds from extracellular matrix. These results suggest that cell adhesion is more likely to occur on TiO2 formed in discrete α-phase regions (hcp depending on its microstructure (grains.

Electric resistivity and thermoelectricity of Ni-Nb-Zr and Ni-Nb-Zr-H glassy alloys

Science.gov (United States)

Fukuhara, Mikio; Inoue, Akihisa

2010-09-01

Electric resistivity ρ and thermoelectric power S of Ni 36Nb 24Zr 40 and (Ni 0.36Nb 0.24Zr 0.4) 90H 10 glassy alloys were investigated in temperature region between 1.5 and 300 K. After resistivity curves of both alloys increase gradually with decreasing temperature down to around 6 K, they dropped suddenly and then reached zero resistivity at 2.1 K, leading to superconductivity. Linear curve with negative TCR of ρ vs T2 and slight increase of S/ T in temperature region down to around 6 K clearly reveal Fermi-liquid phenomenon in electronic state for both alloys independent of hydrogen content.

Electric resistivity and thermoelectricity of Ni-Nb-Zr and Ni-Nb-Zr-H glassy alloys

International Nuclear Information System (INIS)

Fukuhara, Mikio; Inoue, Akihisa

2010-01-01

Electric resistivity ρ and thermoelectric power S of Ni 36 Nb 24 Zr 40 and (Ni 0.36 Nb 0.24 Zr 0.4 ) 90 H 10 glassy alloys were investigated in temperature region between 1.5 and 300 K. After resistivity curves of both alloys increase gradually with decreasing temperature down to around 6 K, they dropped suddenly and then reached zero resistivity at 2.1 K, leading to superconductivity. Linear curve with negative TCR of ρ vs T 2 and slight increase of S/T in temperature region down to around 6 K clearly reveal Fermi-liquid phenomenon in electronic state for both alloys independent of hydrogen content.

Calorimetric measurements of the Ca-Li liquid alloys

Directory of Open Access Journals (Sweden)

Dębski A.

2017-01-01

Full Text Available The ternary Cu-Al-Sn phase diagram is the base for several important types of alloys, with relevant industrial interest and applications. The knowledge of the melting/solidification alloys characteristics are determinant for their preparation and properties control. However, there is a lack of experimental information on the ternary phase diagram, at high temperature. In this work, several alloys, with high copper content and additions of Al, up to 10%, and Sn, up to 14% (in wt%, were studied by thermal analysis and by isothermal phase equilibria determination. The alloys liquidus and solidus lines and the binary α + β phase field, at 800 °C, are presented for the studied range of compositions.

High-strength uranium-0.8 weight percent titanium alloy penetrators

International Nuclear Information System (INIS)

Northcutt, W.G.

1978-09-01

Long-rod kinetic-energy penetrators, produced from a uranium-0.8 titanium (U-0.8 Ti) alloy, are normally water quenched from the gamma phase (approximately 800 0 C) and aged to the desired hardness and strength levels. High cooling rates from 800 0 C in U-0.8 Ti alloy cylindrical bodies larger than about 13 mm in diameter cause internal voids, while slower rates of cooling can produce material that is unresponsive to aging. For the present study, elimination of quenching voids was of paramount importance; therefore, a process including the quenching of plate was explored. Vacuum-induction-cast ingots were forged and rolled into plate and cut into blanks from which the penetrators were obtained. Quenched U-0.8 Ti alloy blanks were aged at 350 to 500 0 C to determine the treatment that would provide maximum tensile and impact strengths. Both tensile and impact strengths were maximized by aging in vacuum for six hours at 450 0 C

Desorption dynamics of deuterium in CuCrZr alloy

Science.gov (United States)

Thi Nguyen, Lan Anh; Lee, Sanghwa; Noh, S. J.; Lee, S. K.; Park, M. C.; Shu, Wataru; Pitcher, Spencer; Torcy, David; Guillermain, David; Kim, Jaeyong

2017-12-01

Desorption behavior of deuterium (D2) in CuCrZr alloy was investigated considering sample thickness, loading and baking temperature of deuterium followed by the ITER scopes. Cylindrical specimens of 1, 3, 5 mm thick with 4 mm diameter were exposed to deuterium at a pressure of 25 bar at 120, 240 and 350 °C for 24 h, then baked at 800 °C in a vacuum chamber maintained at a pressure lower than 10-7 Torr. Deuterium desorption characteristics such as desorption rate and amount of deuterium in the sample were estimated by analyzing the desorption peaks monitored with a residual gas analyzer (RGA), and the trapping energy of deuterium was calculated using thermal desorption spectroscopy (TDS). Secondary ion mass spectroscopy (SIMS) results showed that deuterium atoms embedded in the sample at a depth of less than 15 μm and desorbed as low as 400 °C. All absorbed deuterium atoms in the specimen were completely retrieved by dynamic pumping at 800 °C in 15 min. The desorption rate of deuterium per unit area was inversely proportional to the increment of the thickness of the sample, and was proportional to the loading temperature. Based on the assumption that a uniform distribution of interstitial sites for deuterium follows the Femi-Dirac statistics, the result of TDS demonstrated that the CuCrZr alloy has two types of trapping energies, which were estimated to be 62 and 79 kJ/mol.

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments

Energy Technology Data Exchange (ETDEWEB)

Crone, Wendy; Cao, Guoping; Sridhara, Kumar

2013-05-31

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture

Cosmic ray H and He spectra from 2 to 800 TeV/nucleon from the JACEE experiments

International Nuclear Information System (INIS)

Nilsen, B. S.; Cherry, M. L.; Sengupta, K.; Wefel, J. P.; Asakimori, K.; Burnett, T. H.; Iwai, J.; Lord, J.; Olson, E. D.; Strausz, S. C.; Wilkes, R. J.; Zager, E.; Chevli, K.; Gregory, J. C.; Johnson, J.; Shiina, T.; Takahashi, Y.; Christl, M. J.; Derrickson, J. H.; Fountain, W. F.

1997-01-01

Results for the cosmic ray hydrogen and helium spectra up to 800 TeV, near the 'knee' region, are presented. There is no sign of a break in either the hydrogen or helium spectra. The differential power law slopes are 2.80±0.04 for hydrogen and 2.68±0.06 for helium. With these new H and He measurements, together with earlier reported results for the heavier elements, the sum of the spectra give an all-particle spectrum that is in good agreement with the all-particle spectrum measured using extensive air showers

Creep and fatigue properties of Incoloy 800H in a high-temperature gas-cooled reactor (HTGR) helium environment

International Nuclear Information System (INIS)

Chow, J.G.Y.; Soo, P.; Epel, L.

1978-01-01

A mechanical test program to assess the effects of a simulated HTGR helium environment on the fatigue and creep properties of Incoloy 800H and other primary-circuit metals is described. The emphasis and the objectives of this work are directed toward obtaining information to assess the integrity and safety of an HTGR throughout its service life. The helium test environment selected for study contained 40 μ atm H 2 O, 200 μ atm H 2 , 40 μ atm CO, 10 μ atm CO 2 , and 20 μ atm CH 4 . It is believed that this ''wet'' environment simulates that which could exist in a steam-cycle HTGR containing some leaking steam-generator tubes. A recirculating helium loop operating at about 4 psi in which impurities can be maintained at a constant level, has been constructed to supply the desired environment for fatigue and creep testing

Evolution of rapidly solidified NiAlCu(B) alloy microstructure.

Science.gov (United States)

Czeppe, Tomasz; Ochin, Patrick

2006-10-01

This study concerned phase transformations observed after rapid solidification and annealing at 500, 700 and 800 degrees C in 56.3 Ni-39.9 Al-3.8 Cu-0.06 B (E1) and 59.8 Ni-36.0 Al-4.3 Cu-0.06 B (E2) alloys (composition in at.%). Injection casting led to a homogeneous structure of very small, one-phase grains (2-4 microm in size). In both alloys, the phase observed at room temperature was martensite of L1(0) structure. The process of the formation of the Ni(5)Al(3) phase by atomic reordering proceeded at 285-394 degrees C in the case of E1 alloy and 450-550 degrees C in the case of E2 alloy. Further decomposition into NiAl (beta) and Ni(3)Al (gamma') phases, the microstructure and crystallography of the phases depended on the path of transformations, proceeding in the investigated case through the transformation of martensite crystallographic variants. This preserved precise crystallographic orientation between the subsequent phases, very stable plate-like morphology and very small beta + gamma' grains after annealing at 800 degrees C.

Why incoloy 800 was selected as tube material for the new steam generators of Doel 3

International Nuclear Information System (INIS)

Stubbe, J.; Wolters, F.; Somville, P.; De Ranter, K.

1990-01-01

Incoloy 800 or Inconel 690. This was the basic question for the SG of DOEL 3, to be replaced in 1993. A comparative evaluation was made, focused on the service behaviour, more particularly the corrosion resistance. It was concluded that both materials may be considered for SG replacement. They are indeed substantially superior to alloy 600, but none of them is really better than the other one: - they are both nearly completely immune to primary water stress corrosion cracking; - they are both susceptible to some types of attack from the secondary side. To the 690 credit are the globally better performances in the secondary side corrosion tests. However if the aggressive environments which are unlikely to occur at DOEL 3 are discarded, it appears that the margin between 690 and 800 is small. To the 800 credit is the favourable service experience except the secondary side wastage due to phosphate conditioning. 800 was finally selected not only because of favourable economic arguments, but also because of the important weight attributed to the service behaviour by the Belgian Utilities [fr

Equilibrium phase of high-entropy FeCoNiCrCu0.5 alloy at elevated temperature

International Nuclear Information System (INIS)

Lin, C.-M.; Tsai, H.-L.

2010-01-01

The phase transformations of FeCoNiCrCu 0.5 alloy with the as-cast structure and heat-treated structures were studied. The as-cast alloy specimens were first heated at 1050 o C with a holding time of 1 h. Serial heat-treatment processes at 350 o C, 500 o C, 650 o C, 800 o C, 950 o C, 1100 o C, 1250 o C and 1350 o C with a holding time of 24 h were then carried out to understand the phase evolution and the relationship between the microstructure and the hardness of the specimens. The microstructures were investigated and chemical analyses performed by optical microscopy (OM), scanning elector microscopy (SEM), X-ray diffractometer (XRD) and transmission elector microscopy (TEM). The results show that FCC peaks were observed from the X-ray diffraction of the as-cast specimens and a precipitate phase was present in the specimens that had been heated to 950 o C. The hardness of the FeCoNiCrCu 0.5 alloy remained unchanged in the specimens that underwent various heat treatments that were applied in this study.

Hydrogen degradation of the 26H2MF alloy steel in H2SO4 and hydrocarbon environments

International Nuclear Information System (INIS)

Zielinski, A.; Swieczko-Zurek, B.; Michaliak, P.

2004-01-01

The Polish 26H2M alloy steel has been subjected to different heat treatment resulting in different microstructure and fracture appearance. The slow strain rate tests have been made on smooth round specimens in diluted sulphuric acid, boiler fuel and used mineral machine oil. The 26H2MF steel has become relatively immune in neutral boiler fuel and mineral oil and been heavily suffered from hydrogen degradation in acidic environment. The results demonstrate that the 26H2MF steel is highly susceptible to hydrogen degradation but in absence of stress raisers the increased hydrogen absorption in hydrocarbons can cause only small loss of its plasticity. (author) >>>

Properties of protective oxide scales containing cerium on Incoloy 800H in oxidizing and sulfidizing environments. I. Constant-extension-rate study of mechanical properties

NARCIS (Netherlands)

Haanappel, V.A.C.; Fransen, T.; Geerdink, Bert; Gellings, P.J.

1988-01-01

The mechanical properties of ceramic coatings containing cerium oxide, prepared by the sol-gel method and used to protect Incoloy 800H against aggressive environments, are reported. Deformation and cracking behavior in oxidizing and sulfidizing environments has been investigated by

Influence of pretreatment on creep-rupture-strength and creep-behaviour of a matrix-hardening Ni-base-alloy

International Nuclear Information System (INIS)

Schirra, M.

1982-01-01

The creep and time-to-rupture behaviour of the matrix hardening Nickel base alloy Inconel 625 was investigated in the temperature range 650-800 0 C. Three different thermo-mechanical pretreatment were used: I = Hot rolled finish; II = 870 0 C annealed; III = Sol. treatment 1150 0 C 1 h. The temperature range of this study is for samples which have undergone treatment I and II well above the temperatures normally used. The results show an anomalous stress dependence of creep and time-to-rupture at around 750 0 C. The reason is to be found in the very complex precipitation processes occurring while the stress is applied. The results are explained according to findings about precipitation in this type of alloy. (orig.) [de

Understanding H isotope adsorption and absorption of Al-alloys using modeling and experiments (LDRD: #165724)

Energy Technology Data Exchange (ETDEWEB)

Ward, Donald K. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Zhou, Xiaowang [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Karnesky, Richard A. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Kolasinski, Robert [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Foster, Michael E. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Thurmer, Konrad [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Chao, Paul [Carnegie Mellon University, Pittsburgh, PA (United States); Epperly, Ethan Nicholas [Livermore Valley Charter Preparatory High School, Livermore, CA (United States); Zimmerman, Jonathan A. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Wong, Bryan M. [Univ. of California, Riverside, CA (United States); Sills, Ryan B. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States)

2015-09-01

Current austenitic stainless steel storage reservoirs for hydrogen isotopes (e.g. deuterium and tritium) have performance and operational life-limiting interactions (e.g. embrittlement) with H-isotopes. Aluminum alloys (e.g.AA2219), alternatively, have very low H-isotope solubilities, suggesting high resistance towards aging vulnerabilities. This report summarizes the work performed during the life of the Lab Directed Research and Development in the Nuclear Weapons investment area (165724), and provides invaluable modeling and experimental insights into the interactions of H isotopes with surfaces and bulk AlCu-alloys. The modeling work establishes and builds a multi-scale framework which includes: a density functional theory informed bond-order potential for classical molecular dynamics (MD), and subsequent use of MD simulations to inform defect level dislocation dynamics models. Furthermore, low energy ion scattering and thermal desorption spectroscopy experiments are performed to validate these models and add greater physical understanding to them.

Swelling in neutron irradiated nickel-base alloys

International Nuclear Information System (INIS)

Brager, H.R.; Bell, W.L.

1972-01-01

Inconel 625, Incoloy 800 and Hastelloy X were neutron irradiated at 500 to 700 0 C. It was found that of the three alloys investigated, Inconel 625 offers the greatest swelling resistance. The superior swelling resistance of Inconel 625 relative to that of Hastelloy-X is probably related to differences in the concentrations of the minor rather than major alloy constituents, and can involve (a) enhanced recombination of defects in the Inconel 625 and (b) preferential attraction of vacancies to incoherent precipitates. (U.S.)

Galvannealing of (high-)manganese-alloyed TRIP- and X-IP registered -steel

Energy Technology Data Exchange (ETDEWEB)

Blumenau, M. [ThyssenKrupp Steel Europe AG, Bamenohler Strasse 211, D-57402 Finnentrop (Germany); Norden, M. [DOC Dortmunder Oberflaechencentrum GmbH, Eberhardstrasse 12, D-44145 Dortmund (Germany); Friedel, F.; Peters, K. [ThyssenKrupp Steel Europe AG, Kaiser-Wilhelm-Strasse 100, D-47166 Duisburg (Germany)

2010-12-15

In this study the influence of Mn on galvannealed coatings of 1.7% Mn-1.5% Al TRIP- and 23% Mn X-IP registered -steels was investigated. It is shown that the external selective oxides like Mn, Al and Si of the TRIP steel which occur after annealing at 800 C for 60 s at a dew point (DP) of -25 C (5% H{sub 2}) hamper the Fe/Zn-reaction during subsequent galvannealing. Preoxidation was beneficially utilized to increase the surface-reactivity of the TRIP steel under the same dew point conditions. The influence of Mn on the steel alloy was investigated by using a 23% Mn containing X-IP registered -steel which was bright annealed at 1100 C for 60 s at DP -50 C (5% H{sub 2}) to obtain a mainly oxide free surface prior to hot dip galvanizing (hdg) and subsequent galvannealing. As well known from the literature Mn alloyed to the liquid zinc melt stabilizes {delta}-phase at lower temperatures by participating in the Fe-Zn-phase reactions, it was expected that the metallic Mn of the X-IP registered -steel increases the Fe/Zn-reactivity in the same manner. The approximation of the effective diffusion coefficient (D{sub eff}(Fe)) during galvannealing was found to be higher than compared to a low alloyed steel reference. Contrary to the expectation no increased Fe/Zn-reaction was found by microscopic investigations. Residual {eta}- and {zeta}-phase fractions prove a hampered Fe/Zn-reaction. As explanation for the observed hampered Fe/Zn-reaction the lower Fe-content of the high-Mn-alloyed X-IP registered -steel was suggested as the dominating factor for galvannealing. (Copyright copyright 2010 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Magnetic and other properties and sputtering behavior of Co-base amorphous alloy films

International Nuclear Information System (INIS)

Hayashi, K.; Hayakawa, M.; Ochiai, Y.; Matsuda, H.; Ishikawa, W.; Iwasaki, Y.; Aso, K.

1987-01-01

Magnetic and other properties of Co-base amorphous alloy films prepared by sputtering are investigated. A detailed magnetic phase diagram with saturation magnetic flux density, crystallization temperature, and zero-magnetostrictive line on Co-Ta-Zr amorphous alloys were obtained, and the technical knowhow to make a film with well-reproducible characteristics by widely changing the sputtering conditions was related with these physical properties. Especially on alloy sputtering, a phenomenological model for elucidating a composition difference between film and target is presented. After these studies, the film characteristics of B/sub s/ = 12 kG, T/sub x/ = 450 0 C, chemical bondλ/sub s/chemical bond -8 , H/sub c/<10 mOe, and permeabilities of μ(1 MHz) = 7000, μ(100 MHz) = 2000 for the single film of 2 μm in thickness and of μ(1 MHz) = 4000, μ(100 MHz) = 800 for the insulator-sandwiched multilayered film of 10 μm are obtained, and these well-balanced values enable us to apply the materials for high-frequency recording head

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

Science.gov (United States)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-04-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

Science.gov (United States)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-06-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Structural investigation of Fe(Cu)ZrB amorphous alloy

International Nuclear Information System (INIS)

Duhaj, P.; Janickovic, D.

1996-01-01

The crystallization process in Fe 86 (Cu 1 )Zr 7 B 6 and Fe 87 Zr 7 B 6 is investigated using the methods of transmission electron microscopy, electron and X-ray diffraction and resistometry. Two crystallization reactions take place during thermal annealing of amorphous Fe 86 (Cu 1 )Zr 7 B 6 and Fe 87 Zr 7 B 6 alloys. In both alloys the first crystallization begins with the formation of nanocrystalline α-Fe at temperature to approximately 800 K. The second crystallization starts above 1000 K; the nanocrystalline phase dissolves and together with the remaining amorphous matrix form rough grains of α-Fe and dispersed Fe 23 Zr 6 phases. From Moessbauer spectroscopy it seems that there exist two neighbourhoods of Fe atoms in the amorphous structure. One of them is characterized by low Zr content and is responsible for the high-field component of the hyperfine field distribution p(H). The second one is rich in Zr and B and is responsible for the low-field component of p(H). This is in accord with the observation of two crystallization steps separated by a large interval of temperatures due to the existence of two chemically different regions or clusters. (orig.)

Properties of super alloys for high temperature gas cooled reactor

International Nuclear Information System (INIS)

Izaki, Takashi; Nakai, Yasuo; Shimizu, Shigeki; Murakami, Takashi

1975-01-01

The existing data on the properties at high temperature in helium gas of iron base super alloys. Incoloy-800, -802 and -807, nickel base super alloys, Hastelloy-X, Inconel-600, -617 and -625, and a casting alloy HK-40 were collectively evaluated from the viewpoint of the selection of material for HTGRs. These properties include corrosion resistance, strength and toughness, weldability, tube making, formability, radioactivation, etc. Creep strength was specially studied, taking into consideration the data on the creep characteristics in the actual helium gas atmosphere. The necessity of further long run creep data is suggested. Hastelloy-X has completely stable corrosion resistance at high temperature in helium gas. Incoloy 800 and 807 and Inconel 617 are not preferable in view of corrosion resistance. The creep strength of Inconel 617 extraporated to 1,000 deg C for 100,000 hours in air was the greatest rupture strength of 0.6 kg/mm 2 in all above alloys. However, its strength in helium gas began to fall during a relatively short time, so that its creep strength must be re-evaluated in the use for long time. The radioactivation and separation of oxide film in primary construction materials came into question, Inconel 617 and Incoloy 807 showed high induced radioactivity intensity. Generally speaking, in case of nickel base alloys such as Hastelloy-X, oxide film is difficult to break away. (Iwakiri, K.)

Phase transformations on Zr-Nb alloys

International Nuclear Information System (INIS)

Doi, Sergio Norifumi

1980-01-01

This research intended the laboratory scale experimental development of Zr-Nb alloys with adequate characteristics for use as fuel element cladding or for the making of irradiation capsules. Zr-Nb alloys with different Nb contents were melted and the resulting material was characterised. The following metallurgical aspects were considered: preparation of Zr-Nb alloys with various Nb contents; heat and thermomechanical treatments; microstructural characterization; mechanical properties; oxidation properties. The influence of the heat treatment and thermomechanical treatment, on the out-of-pile mechanical and oxidation properties of the Zr-Nb alloys were studied. It was found that the alloy microhardness increases with the Nb content and/or with the thermomechanical treatment. Mechanical properties such as yield and ultimate tensile strength as well as elongation were determined by means of compression tests. The results showed that the alloy yield stress increases with the Nb content and with the thermomechanical treatment, while its elongation decreases. Thermogravimetric analysis determined the alloy oxidation kinetics, in the 400 - 800 deg C interval, at 1 atm. oxygen pressure. The results showed that the alloy oxidation rate increases with the temperature and Nb content. It was also observed that the oxidation rate increases considerably for temperatures higher than 600 deg C.(author)

Evaluation of the Control Rod Super Alloy Material of HTR-PM

International Nuclear Information System (INIS)

Li Pengjun; Yan He; Diao Xingzhong

2014-01-01

The control rod drive mechanism (CRDM) system is served as the first reactivity control and shutdown system for the high temperature reactor pebble-bed module (HTR-PM) in Shandong, China. And the control rod, which is pulled up and down by a chain sprocket mechanism of CRDM to realize reactivity control, compensation and shutdown, has to be durable under temperature as high as 550℃ for a long time. Thus the material persistent strength under high temperature is quite important for the reliability of the CRDM. In this paper, a review on material selection of control rod of high temperature gas cooled reactors, including AVR and THTR-300 in Germany, HTTR in Japan, PBMR in South Africa and Dragon in Britain, was summarized. The major parameters of two kinds of high temperature alloy, incoloy 800H and alloy 625, were compared and discussed. According to the ASME NH volume, a design criterion for the control rod was established and applied in the analysis of the chain by using finite element method. The numerical simulations showed that the chain made of alloy 625 could meet the condition and work for a long time under high temperature. (author)

Hot corrosion of Ti–46Al–8Ta (at.%) intermetallic alloy

International Nuclear Information System (INIS)

Godlewska, E.; Mitoraj, M.; Leszczynska, K.

2014-01-01

Highlights: •Cyclic oxidation tests with salt deposits were conducted on Ti–46Al–8Ta (at.%) alloy. •Mineral contaminants had detrimental effect on oxidation resistance. •Sodium chloride appeared to be the most hazardous among salts used. •Significant material losses were attributed to self-sustaining reaction mechanism. -- Abstract: Hot corrosion behaviour of a fully lamellar Ti–46Al–8Ta (at.%) alloy was studied in air under thermal cycling conditions (20-h cycles) at 700 and 800 °C. The samples were purposely contaminated with salt deposits consisting of NaCl or Na 2 SO 4 or a mixture of these. The progress of degradation was followed by mass change measurements and visual inspection. Post-exposure examination involved scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The composition of salt deposits clearly influenced the rate and type of corrosion. Sodium chloride appeared especially harmful because of the formation of volatile chloride species

Three-dimensional microstructure-based micromechanical modeling for TC6 titanium alloy

Energy Technology Data Exchange (ETDEWEB)

Li, Guoju; Shi, Ran [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); National Key Laboratory of Science and Technology on Materials Under Shock and Impact, Beijing 100081 (China); Fan, Qunbo, E-mail: fanqunbo@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); National Key Laboratory of Science and Technology on Materials Under Shock and Impact, Beijing 100081 (China); Xia, Yumeng; Zhang, Hongmei [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); National Key Laboratory of Science and Technology on Materials Under Shock and Impact, Beijing 100081 (China)

2017-02-08

A new in-depth evaluation of the micromechanical response of TC6 (Ti–6Al–1.5Cr–2.5Mo–0.5Fe–0.3Si) titanium alloy subjected to uniaxial tensile loading is performed based on micromechanical modeling. This evaluation includes reconstruction of the three-dimensional annealed microstructure (annealing at 800 °C for 2 h, then air cooled) of the alloy via dual-energy micro-computed tomography. In addition, constitutive relations of the constituent phases were determined via synchrotron-based in-situ high-energy X-ray diffraction and a self-consistent model as well as nanoindentation tests combined with finite element modeling. The results revealed that the stress concentration was translated from the primary α phase to the secondary α phase, then to the β phase. Moreover, the stress generated was re-transferred to the primary α phase when the strain was increased from 0.00 to 0.05. This transfer is indicative of crack initiation in the primary α grains.

Microstructure Stability of Inconel 740H Alloy After Long Term Exposure at 750℃

Directory of Open Access Journals (Sweden)

DANG Ying-ying

2016-09-01

Full Text Available Unstressed exposure tests of Inconel 740H alloy tube were carried out at 750℃ for 500-3000h. The microstructure evolution and microhardness were studied by means of thermodynamic simulation, OM, FEG-SEM and microhardness testing. The results show that the tube is qualified if both chemical composition and tensile properties of the as-received alloy meet the corresponding requirements of ASME. After long term exposure, the main precipitates are γ' and M23C6, and no η and σ phase. With the prolonging of exposure time, the coarsening of γ' becomes faster and the law of relationship between the radius of γ' and time accords with LSW Ostwald ripening law; meanwhile, the change in size of M23C6 is not so obvious. During the whole process, microhardness increases firstly and then decreases, but the fluctuation is slight. The changes of microstructure and hardness indicate that, after long time exposure, the domestic Inconel 740H has good stability and can be used for further carrying out the investigation on the mechanical property of creep-rupture.

Effect of Annealing Temperature on the Corrosion Protection of Hot Swaged Ti-54M Alloy in 2 M HCl Pickling Solutions

Directory of Open Access Journals (Sweden)

El-Sayed M. Sherif

2017-01-01

Full Text Available The corrosion of Ti-54M titanium alloy processed by hot rotary swaging and post-annealed to yield different grain sizes, in 2 M HCl solutions is reported. Two annealing temperatures of 800 °C and 940 °C, followed by air cooling and furnace cooling were used to give homogeneous grain structures of 1.5 and 5 μm, respectively. It has been found that annealing the alloy at 800 °C decreased the corrosion of the alloy, with respect to the hot swaged condition, through increasing its corrosion resistance and decreasing the corrosion current and corrosion rate. Increasing the annealing temperature to 940 °C further decreased the corrosion of the alloy.

Effect of Fe, Ni, and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy under different pH conditions

Directory of Open Access Journals (Sweden)

Mohammad Salim Kaiser

2018-05-01

Full Text Available Effect of Fe, Ni and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy was studied. The test of corrosion behaviour at different environmental pH 1, 3, 5, 7, 9, 11 and 13 was performed using conventional gravimetric measurements and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM and X-ray analyser (EDX investigations. The highest corrosion rate was observed at pH 13 followed by pH 1, while in the pH range of 3.0 to 11, there is a high protection of surface due to formation of stable surface oxide film. The highest corrosion rate at pH 13 is due to presence of sodium hydroxide in the solution in which the surface oxide film is soluble. At pH 1, however, high corrosion rate can be attributed to dissolution of Al due to the surface attack by aggressive chloride ions. Presence of Fe, Ni and Cr in hyper-eutectic Al-Si automotive alloy has significant effect on the corrosion rate at both environmental pH values. Resistivity of alloy surfaces initially decreases at pH 1 and pH 13 due to formation of thin films. The SEM images of corroded samples immersed in pH 1 solution clearly show pores due to uniform degradation of the alloy. In pH 13 solution, however, the corrosion layer looks more packed and impermeable.

Nitrogen Recovery by Fe-Ti Alloy from Molten Lithium at High Temperatures

International Nuclear Information System (INIS)

Juro Yagi; Akihiro Suzuki; Takayuki Terai; Takeo Muroga

2006-01-01

Molten lithium will be used as a beam target of IFMIF (International Fusion Materials Irradiation Facility), and is also expected as a self-cooling and tritium breeding material in fusion reactors. Since tritium is generated in both cases, tritium recovery is required from viewpoints of safety and a feasible fuel cycle. Nitrogen impurity in the lithium, however, not only enhance corrosion to tubing materials, but also promote nitride contamination on a surface of yttrium, which is considered to be a tritium gettering candidate. In our previous study, nitrogen recovery by hot trap method with Fe + 5%Ti alloy as a gettering material showed a higher nitrogen reduction capacity than that with Ti or Cr metal. In this study, high temperature recovery of nitrogen with Fe-Ti alloy was examined to achieve more efficient recovery and higher recovery rate coefficient. Fe - 4%Ti alloy are fabricated by electron beam melting, and its thin plates (40 mm x 10 mm x 1 mm) are used in our experiments. The Fe - 4%Ti alloy plates were immersed into 25 g of liquid lithium in Mo crucible under Ar atmosphere. The crucible was put in a SUS316 stainless steel pot heated at 600, 700, or 800 o C up to 100 hours. A small portion of the liquid lithium in the crucible was sampled out with adequate time interval, and the nitrogen concentrations in the sampled lithium were observed by changing nitrogen to ammonia. Experiments using lithium containing about 100 wt. ppm of nitrogen at the beginning show that the nitrogen reduction became faster with temperature and the minimum achieved nitrogen concentration was less than 20 wppm in case of 800 C. SEM-EDS analysis on the plates after experiment shows a Ti-rich surface layer of tens of micrometers on the alloy immersed in lithium at 800 C, and XPS analysis indicates the surface layer is TiN, while no Ti-rich layer nor TiN were observed on the alloys immersed at 600 o C and 700 o C. By increasing temperature from 600 o C to 800 o C, the diffusion

Calculations of hydrogen diffusivity in Zr-based alloys: Influence of alloying elements and effect of stress

International Nuclear Information System (INIS)

Yu, J.; Jiang, C.; Zhang, Y.

2017-01-01

This report summarizes the progress on modeling hydrogen diffusivity in Zr-based alloys. The presence of hydrogen (H) can detrimentally affect the mechanical properties of many metals and alloys. To mitigate these detrimental effects requires fundamental understanding of the thermodynamics and kinetics governing H pickup and hydride formation. In this work, we focus on H diffusion in Zr-based alloys by studying the effects of alloying elements and stress, factors that have been shown to strongly affect H pickup and hydride formation in nuclear fuel claddings. A recently developed accelerated kinetic Monte Carlo method is used for the study. It is found that for the alloys considered here, H diffusivity depends weakly on composition, with negligible effect at high temperatures in the range of 600-1200 K. Therefore, the small variation in compositions of these alloys is likely not a major cause of the very different H pickup rates. In contrast, stress strongly affects H diffusivity. This effect needs to be considered for studying hydride formation and delayed hydride cracking.

Calculations of hydrogen diffusivity in Zr-based alloys: Influence of alloying elements and effect of stress

Energy Technology Data Exchange (ETDEWEB)

Yu, J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2017-06-01

This report summarizes the progress on modeling hydrogen diffusivity in Zr-based alloys. The presence of hydrogen (H) can detrimentally affect the mechanical properties of many metals and alloys. To mitigate these detrimental effects requires fundamental understanding of the thermodynamics and kinetics governing H pickup and hydride formation. In this work, we focus on H diffusion in Zr-based alloys by studying the effects of alloying elements and stress, factors that have been shown to strongly affect H pickup and hydride formation in nuclear fuel claddings. A recently developed accelerated kinetic Monte Carlo method is used for the study. It is found that for the alloys considered here, H diffusivity depends weakly on composition, with negligible effect at high temperatures in the range of 600-1200 K. Therefore, the small variation in compositions of these alloys is likely not a major cause of the very different H pickup rates. In contrast, stress strongly affects H diffusivity. This effect needs to be considered for studying hydride formation and delayed hydride cracking.

FTIR study of the influence of minor alloying elements on the high temperature oxidation of nickel alloys

International Nuclear Information System (INIS)

Lenglet, M.; Delaunay, F.; Lefez, B.

1997-01-01

The purpose of this paper is to study the reflectance spectra of the different single oxide layer systems : Cr 2 O 3 /Fe, MnCr 2 O 4 /Fe, TiO 2 /Fe, NiCr 2 O 4 /Fe and NiFe 2 O 4 /Fe and to extend the theoretical calculations to multilayer oxide systems on metallic substrates. The interpretation of the resulting reflectance spectra for these systems is used to explain the initial stages of oxide formation and the influence of minor alloying elements on the high temperature oxidation of three commercial nickel alloys : Incoloy 800, Inconel 600 and X. (orig.)

High-Temperature Test of 800HT Printed Circuit Heat Exchanger in HELP

International Nuclear Information System (INIS)

Kim, Chan Soo; Hong, Sung-Deok; Kim, Min Hwan; Shim, Jaesool

2014-01-01

Korea Atomic Energy Research Institute has developed high-temperature Printed Circuit Heat Exchangers (PCHE) for a Very High Temperature gas-cooled Reactor and operated a very high temperature Helium Experimental LooP (HELP) to verify the performance of the high temperature heat exchanger at the component level environment. PCHE is one of the candidates for the intermediate heat exchanger in a VHTR, because its design temperature and pressure are larger than any other compact heat exchanger types. High temperature PCHEs in HELP consist of an alloy617 PCHE and an 800HT PCHE. This study presents the high temperature test of an 800HT PCHE in HELP. The experimental data include the pressure drops, the overall heat transfer coefficients, and the surface temperature distributions under various operating conditions. The experimental data are compared with the thermo-hydraulic analysis from COMSOL. In addition, the single channel tests are performed to quantify the friction factor under normal nitrogen and helium inlet conditions. (author)

Anisotropic behavior studies of aluminum alloy 5083-H0 using a micro-tensile test stage in a FEG-SEM

CSIR Research Space (South Africa)

Motsi, GT

2016-02-01

Full Text Available stream_source_info Motsi_18197_2016.pdf.txt stream_content_type text/plain stream_size 1246 Content-Encoding UTF-8 stream_name Motsi_18197_2016.pdf.txt Content-Type text/plain; charset=UTF-8 Materials Science... & Engineering A, vol. 656: 266-274 Anisotropic behavior studies of aluminum alloy 5083-H0 using a micro-tensile test stage in a FEG-SEM Motsi GT Shongwe MB Sono TJ Olubambi PA ABSTRACT: The plastic anisotropic characteristics of aluminum alloy 5083-H...

The Effect of Heat Treatment on the Sensitized Corrosion of the 5383-H116 Al-Mg Alloy

Directory of Open Access Journals (Sweden)

Ying-Kai Lin

2017-03-01

Full Text Available In this study, the effects of heat treatment and sensitized corrosion on the 5383-H116 Al-Mg alloy were investigated for temperatures ranging from 100 to 450 °C. The results show that the heat treatment temperature is the main factor that causes changes to the microstructure and mechanical strength of the 5383-H116 Al-Mg alloy, inducing β-phase (Al3Mg2 precipitation in the form of a continuous layer along the grain boundaries. Intergranular corrosion was caused by the β-phase of the grain boundary precipitation, and the corrosion susceptibility of the recrystallized structure was significantly higher than the corrosion susceptibility of the recovered structure. According to the conductivity values detected, β-phase precipitation can enhance the 5383-H116 Al-Mg alloy conductivity, with the response due to structural dislocation density being higher than that due to the recrystallized structure. As such, the β-phase precipitation after sensitization is more significant than the β-phase precipitation prior to the sensitization, such that after sensitization, the conductivity rises to a significantly higher level than that exhibited by the recrystallization structure.

Characteristics of Film Formed on Alloy 600 and Alloy 690 in Water Containing lead

International Nuclear Information System (INIS)

Hwang Seong Sik; Lee, Deok Hyun; Kim, Hong Pyo; Kim, Joung Soo; Kim, Ju Yup

1999-01-01

Anodic polarization behaviors of Alloy 600 and Alloy 690 have been studied as a function of lead content in the solution of pH 4 and 10 at 90 .deg. C. As the amount of lead in the solution increased, critical current densities and passive current densities of Alloy 600 and Alloy 690 increased, while the breakdown potential of the alloys decreased. The high critical current density in the high lead solution was thought to come from the combination of an enhanced dissolution of constituents on the surface of the alloys by the lead and an anodic dissolution of metallic lead deposited on the surface of the specimens. The morphology of lead precipitated on the specimen after the anodic scan changed with the pH of solution: small irregular particles were precipitated on the surface of the specimen in the solution of pH 4, while the high density of regular sized particles was formed on it in the solution of pH 10.Pb was observed to enhance Cr depletion from the outer surface of Alloy 600 and Alloy 690 and also to increase the ratio of O 2- /OH - in the surface film formed in the high lead solution. The SCC resistance of Alloy 600 and Alloy 690 may have decreased due to the poor quality of the passive film formed and the enhanced oxygen evolution in the solution containing lead

Stress-corrosion cracking properties of candidate fuel cladding alloys for the Canadian SCWR: a summary of literature data and recent test results

Energy Technology Data Exchange (ETDEWEB)

Zheng, W.; Zeng, Y., E-mail: Wenyue@NRcan.gc.ca [CanmetMATERIALS, Hamilton, ON (Canada); Luo, J. [Univ. of Alberta, Edmonton, AB (Canada); Novotny, R. [JRC-European Commission, Patten (Netherlands); Li, J.; Amirkhiz, B.S., E-mail: Jian.li@nrcan.gc.ca [CanmetMATERIALS, Hamilton, ON (Canada); Guzonas, D. [Atomic Energy of Canada Limited, Chalk River, ON (Canada); Matchim, M.; Collier, J.; Yang, L., E-mail: lin.yang@nrcan.gc.ca [CanmetMATERIALS, Hamilton, ON (Canada)

2014-07-01

Cracking of fuel claddings is a serious concern when selecting candidate alloys for the development of a next-generation reactor. Whether the cracking is due to an environment-metal interaction such as stress-corrosion, or a pure metallurgical process such as localized plastic deformation along grain boundaries, the final impact is the same: cracking of the cladding can lead to fuel failure. In the course of a review of potential candidate alloys in preparation for further assessment under conditions relevant to the Canadian SCWR concept, relevant cracking studies reported for five short-listed alloys (namely 310S, 347H, 800H, 625 and 214) in the open literature were examined, and the key findings are provided in this paper. Discussions are also made of the recent SCC data from capsule tests and slow-strain rate tests (SSRT) in supercritical water. The data suggest that there is a threshold strain level below which SCC is not developed during SSRT tests. The practical implication of this finding is also discussed. (author)

Elevated-Temperature Corrosion of CoCrCuFeNiAl0.5Bx High-Entropy Alloys in Simulated Syngas Containing H2S

Energy Technology Data Exchange (ETDEWEB)

Dogan, Omer N; Nielsen, Benjamin C; Hawk, Jeffrey A

2013-08-01

High-entropy alloys are formed by synthesizing five or more principal elements in equimolar or near equimolar concentrations. Microstructure of the CoCrCuFeNiAl{sub 0.5}B{sub x} (x = 0, 0.2, 0.6, 1) high-entropy alloys under investigation is composed of a mixture of disordered bcc and fcc phases and borides. These alloys were tested gravimetrically for their corrosion resistance in simulated syngas containing 0, 0.01, 0.1, and 1 % H{sub 2}S at 500 °C. The exposed coupons were characterized using XRD and SEM. No significant corrosion was detected at 500 °C in syngas containing 0 and 0.01 % H{sub 2}S while significant corrosion was observed in syngas containing 0.1 and 1 % H{sub 2}S. Cu{sub 1.96}S was the primary sulfide in the external corrosion scale on the low-boron high-entropy alloys, whereas FeCo{sub 4}Ni{sub 4}S{sub 8} on the high-boron high-entropy alloys. Multi-phase Cu-rich regions in the low-B high-entropy alloys were vulnerable to corrosive attack.

Modelling the long-term corrosion behaviour of candidate alloys for Canadian SCWR

Energy Technology Data Exchange (ETDEWEB)

Steeves, G.; Cook, W., E-mail: wcook@unb.ca, E-mail: graham.steeves@unb.ca [University of New Brunswick, Department of Chemical Engineering, Fredericton, NB (Canada)

2015-07-01

Corrosion behaviour of Inconel 625 and Incoloy 800H, two of the candidate fuel cladding materials for Canadian supercritical water (SCW) reactor designs, were evaluated by exposing the metals to SCW in UNB's SCW flow loop. Individual experiments were conducted over a range of 370{sup o}C and 600{sup o}C. Exposure times were typically intervals of 100, 250, and 500 hours. Experimental data was used to create an empirical kinetic equation for each material. Activation energies for the alloys were determined, and showed a distinct difference between low-temperature electrochemical corrosion mechanism and direct high-temperature chemical oxidation. (author)

Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere

Energy Technology Data Exchange (ETDEWEB)

Li, Weizhen; Nie, Lei; Chen, Ying; Kovarik, Libor; Liu, Jun; Wang, Yong

2017-04-01

With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\

Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

Science.gov (United States)

Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

2012-06-01

Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

Thermodiffusion Mo-B-Si coating on VN-3 niobium alloy

International Nuclear Information System (INIS)

Kozlov, A.T.; Lazarev, Eh.M.; Monakhova, L.A.; Shestova, V.F.; Romanovich, I.V.

1985-01-01

Protective properties of complex Mo-B-Si-coating on niobium alloy VN-3 (4.7 mass.% Mo, 1.1 mass.% Zr, 0.1 mass.% C) have been studied. It is established, that the complex Mo-B-Si-coating ensures protection from oxidation of niobium alloys in the temperature range of 800-1200 degC for 1000-1500 hr, at 1600 degC - for 10 hr. High heat resistance of Mo-B-Si - coating at 800-1200 degC is determined by the presence of amorphous film of SiOΛ2 over the layer MoSiΛ2 and barrier boride layer on the boundary with the metal protected; decrease in the coating heat resistance at 1600 degC is related to the destruction of boride layer, decomposition of MoSiΛ2 for lower cilicides and loosening of SiOΛ2 film

H-Phase Precipitation and Martensitic Transformation in Ni-rich Ni-Ti-Hf and Ni-Ti-Zr High-Temperature Shape Memory Alloys

Science.gov (United States)

Evirgen, A.; Pons, J.; Karaman, I.; Santamarta, R.; Noebe, R. D.

2018-03-01

The distributions of H-phase precipitates in Ni50.3Ti29.7Hf20 and Ni50.3Ti29.7Zr20 alloys formed by aging treatments at 500 and 550 °C or slow furnace cooling and their effects on the thermal martensitic transformation have been investigated by TEM and calorimetry. The comparative study clearly reveals faster precipitate-coarsening kinetics in the NiTiZr alloy than in NiTiHf. For precipitates of a similar size of 10-20 nm in both alloys, the martensite plates in Ni50.3Ti29.7Zr20 have larger widths and span a higher number of precipitates compared with the Ni50.3Ti29.7Hf20 alloy. However, for large H-phase particles with hundreds of nm in length, no significant differences in the martensitic microstructures of both alloy systems have been observed. The martensitic transformation temperatures of Ni50.3Ti29.7Hf20 are 80-90 °C higher than those of Ni50.3Ti29.7Zr20 in the precipitate-free state and in the presence of large particles of hundreds on nm in length, but this difference is reduced to only 10-20 °C in samples with small H-phase precipitates. The changes in the transformation temperatures are consistent with the differences in the precipitate distributions between the two alloy systems observed by TEM.

Mechanical characterization of metallic materials for high-temperature gas-cooled reactors in air and in helium environments

International Nuclear Information System (INIS)

Sainfort, G.; Cappelaere, M.; Gregoire, J.; Sannier, J.

1984-01-01

In the French R and D program for high-temperature gas-cooled reactors (HTGRs), three metallic alloys were studied: steel Chromesco-3 with 2.25% chromium, alloy 800H, and Hastelloy-X. The Chromesco-3 and alloy 800H creep behavior is the same in air and in HTGR atmosphere (helium). The tensile tests of Hastelloy-X specimens reveal that aging has embrittlement and hardening effects up to 700 0 C, but the creep tests at 800 0 C show opposite effects. This particular behavior could be due to induced precipitation by aging and the depletion of hardening elements from the matrix. Tests show a low influence of cobalt content on mechanical properties of Hastelloy-X

Investigation of the behaviour of 35% nickel alloys in the presence of helium coolant impurities

International Nuclear Information System (INIS)

Dixmier, J.; Leclercq, D.; Olivier, P.; Vincent, L.; Willermoz, H.

1976-01-01

Alloys of the Incoloy 800 type containing 35% nickel are being considered for the heat exchangers of steam-cycle high-temperature reactors for electricity production. Corrosion tests at 650 and 800 0 C have been carried out at atmospheric pressure and at 50 bar on four such alloys (commercially available and specially produced ones) with different titanium and aluminium contents. It appears that the degree of intergranular attack occurring in these materials increases with the titanium and aluminium concentration. Examination with a scanning electron microscope fitted with analysers confirms the decisive role of these two elements which are actually to be found in oxidized form at the grain boundaries to the exclusion of other components of the alloy. This type of corrosion can lead in the long run to a deterioration in the alloy's mechanical characteristics at high temperature. To assess the true risk of in-service rupture, various rigs have been developed for investigating corrosion under stress conditions. The atmosphere in these rigs consists of helium, of which the impurity content is rigorously controlled. In particular, the Aida high-pressure loop installed at the Grenoble Nuclear Research Centre can accommodate a large number of test-pieces. These are either subjected to a definite tensile stress or placed in a circuit through which helium is passed at high velocity. At present experiments are being conducted at 700 and 750 0 C on an Incoloy 800 alloy corresponding to the designers' specifications. The experiments are performed at atmospheric pressure and a pressure of 50 bar with the same impurity pressures. (author)

Effect of composition and heat treatment on carbide phases in Ni-Mo alloys

International Nuclear Information System (INIS)

Svistunova, T.V.; Tsvigunov, A.N.; Stegnukhina, L.V.; Sakuta, N.D.

1984-01-01

The investigation results of vanadium, iron, carbon and silicon effect and heat treatment regime on the type and composition of carbides in Ni-(26...31)%Mo alloys are presented. It is shown that type, composition and quantity of carbide phases forming in alloys are determined not only by molybdenum and carbon content, but presence of other elements (V, Fe), admixtures (C, Si) and reducers as well as by regime of thermal treatment. In the alloy, containing 26...31% Mo, 0.01...0.03% C ( 12 C type with a=1.083...1.089 nm lattice parameter, in which V and Ti, Fe and Si are presented besides Mo and Ni. In the temperature range of 600-800 deg C high dispersed carbides segregate on grain boundaries. Silicon initiates segregation of the carbide phases among them by grain boundaries at the temperatures of 800 deg C as well as regulates carbide of M 12 C type with a=1.094...1.098 nm lattice parameter

Evaluation of cast Ti-Fe-O-N alloys for dental applications

International Nuclear Information System (INIS)

Koike, Marie; Ohkubo, Chikahiro; Sato, Hideki; Fujii, Hideki; Okabe, Toru

2005-01-01

Good mechanical properties, biocompatibility and corrosion resistance make titanium an excellent material for biomedical applications. However, when better mechanical properties than those offered by commercially pure titanium (CPTi) are needed, Ti-6Al-4V is sometimes a good alternative. Some new titanium alloys, developed as industrial structural materials, aim at an intermediate range of strength between that of CP Ti and Ti-6Al-4V. Two of these alloys are Super-TIX800TM (Ti-1% Fe-0.35% O-0.01% N) and Super-TIX800NTM (Ti-1% Fe-0.3% O-0.04% N) (both produced by Nippon Steel Corp., Japan). Besides being stronger than CP Ti, the cost of manufacturing these alloys is reportedly lower than for Ti-6Al-4V since they do not contain any expensive elements. In addition, they are not composed of elements such as aluminum or vanadium, which have caused biocompatibility concerns in medical and dental appliances. To evaluate these alloys as candidates for dental use, it is helpful to compare them to CP Ti (ASTM Grade 2) and Ti-6Al-4V (ASTM Grade 5), which have already been employed in dentistry. We evaluated the tensile properties, mold filling capacity, corrosion characteristics and grindability of these industrial alloys prepared by investment casting. Compared to the strengths of cast CPTi, the yield strength and tensile strength of these cast alloys were more than 20% and approximately 30% higher, respectively. On the other hand, both of these properties were 30% lower than for Ti-6Al-4V. Better grindability and wear resistance were additional benefits of these new alloys for dental applications

Nickel-plating for active metal dissolution resistance in molten fluoride salts

Energy Technology Data Exchange (ETDEWEB)

Olson, Luke [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States); Sridharan, Kumar, E-mail: kumar@engr.wisc.edu [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States); Anderson, Mark; Allen, Todd [Department of Engineering Physics, 1500 Engineering Drive, University of Wisconsin, Madison, WI 53706 (United States)

2011-04-15

Ni electroplating of Incoloy-800H was investigated with the goal of mitigating Cr dissolution from this alloy into molten 46.5%LiF-11.5%NaF-42%KF eutectic salt, commonly referred to as FLiNaK. Tests were conducted in graphite crucibles at a molten salt temperature of 850 deg. C. The crucible material graphite accelerates the corrosion process due to the large activity difference between the graphite and the alloy. For the purposes of providing a baseline for this study, un-plated Incoloy-800H and a nearly pure Ni-alloy, Ni-201 were also tested. Results indicate that Ni-plating has the potential to significantly improve the corrosion resistance of Incoloy-800H in molten fluoride salts. Diffusion of Cr from the alloy through the Ni-plating does occur and if the Ni-plating is thin enough this Cr eventually dissolves into the molten salt. The post-corrosion test microstructure of the Ni-plating, particularly void formation was also observed to depend on the plating thickness. Diffusion anneals in a helium environment of Ni-plated Incoloy-800H and an Fe-Ni-Cr model alloy were also investigated to understand Cr diffusion through the Ni-plating. Further enhancements in the efficacy of the Ni-plating as a protective barrier against Cr dissolution from the alloy into molten fluoride salts can be achieved by thermally forming a Cr{sub 2}O{sub 3} barrier film on the surface of the alloy prior to Ni electroplating.

Cyclic tensile response of Mo-27 at% Re and Mo-0.3 at% Si solid solution alloys

Energy Technology Data Exchange (ETDEWEB)

Yu, X.J.; Kumar, K.S., E-mail: Sharvan_Kumar@brown.edu

2016-10-31

Stress-controlled uniaxial cyclic tensile tests were conducted on binary Mo-27 at% Re and Mo-0.3 at% Si solid solutions as a function of temperature and compared against the previously reported cyclic response of pure Mo. The Mo-27 at% Re alloy with a recrystallized grain size of ~30 µm was evaluated in the temperature range 25 °C–800 °C at R=0.1 and stress range that was 80% of the ultimate tensile strength (UTS); a peak in fatigue life was observed between 300 °C and 500 °C. The decrease in fatigue life at the higher temperatures of 700 °C and 800 °C is attributed to dynamic strain aging. Transmission electron microscopy of the cyclically-deformed alloy revealed parallel bands of dislocation at room temperature that transitioned to a uniform cell structure at 500 °C and back to orthogonal planar arrays at 800 °C. The as-extruded Mo-0.3 at% Si alloy was evaluated from 25 °C to 1200 °C and showed superior fatigue life and ratcheting strain resistance as compared to pure Mo and the Mo-27 at% Re alloy (within the temperature range where data were available for comparison). The superior resistance is attributed to the high density of dislocations within the material in this mostly unrecrystallized state rather than Si in solid solution. Above 800 °C, the ratcheting strain increases and fatigue life decreases rapidly with increasing temperature and is associated with dynamic recovery.

The Effects of CO{sub 2} Pressure on Corrosion and Carburization Behaviors of Chromia-forming Austenitic Alloys

Energy Technology Data Exchange (ETDEWEB)

Lee, Ho Jung; Kim, Sung Hwan; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

2015-05-15

By applying S-CO{sub 2} cycle to SFR, the inherent safety could be improved by alleviating the concern of explosive reaction between high temperature steam and liquid sodium as well as increased thermal efficiency at 500-550 .deg. C compared to helium Brayton cycle. Meanwhile, from the material point of view, a compatibility such as corrosion and carburization of candidate materials in S-CO{sub 2} environment should be evaluated to assure the long-term integrity of IHX. It has been previously reported that Ni-base alloys and high-Cr Fe-base austenitic alloys showed a good corrosion resistance by the formation of thin chromia layer while carburization behaviors of those materials were not properly investigated. Corrosion and carburization behaviors of three chromia-forming austenitic alloys (Ni-base alloys and Alloy 800HT) were evaluated in S-CO{sub 2} (200 bar) and CO{sub 2} (1 bar) environment at 550.650 .deg. C for 1000 h. For all test materials, a good corrosion resistance was exhibited by the formation of thin chromia (Cr{sub 2}O{sub 3}) with small amount of minor oxides such as Mn1.5Cr1.5O{sub 4}, Al{sub 2}O{sub 3}, and TiO{sub 2}.

Oxidation behaviour of bulk W-Cr-Ti alloys prepared by mechanical alloying and HIPing

International Nuclear Information System (INIS)

García-Rosales, C.; López-Ruiz, P.; Alvarez-Martín, S.; Calvo, A.; Ordás, N.; Koch, F.; Brinkmann, J.

2014-01-01

Self-passivating tungsten based alloys are expected to provide a major safety advantage compared to pure tungsten when used as first wall armour of future fusion reactors, due to the formation of a protective oxide scale, preventing the formation of volatile and radioactive WO 3 in case of a loss of coolant accident with simultaneous air ingress. In this work results of isothermal oxidations tests at 800 and 1000 °C on bulk alloy WCr12Ti2.5 performed by thermogravimetric analysis (TGA) and by exposure to flowing air in a furnace are presented. In both cases a thin, dense Cr 2 O 3 layer is found at the outer surface, below which a Cr 2 WO 6 scale and Ti 2 CrO 5 layers alternating with WO 3 are formed. The Cr 2 O 3 , Cr 2 WO 6 and Ti 2 CrO 5 scales act as protective barriers against fast inward O 2− diffusion. The oxidation kinetics seems to be linear for the furnace exposure tests while for the TGA tests at 800 °C the kinetics is first parabolic, transforming into linear after an initial phase. The linear oxidation rates are 2–3 orders of magnitude lower than for pure W

Creep rupture strength and creep behavior of low-activation martensitic OPTIFER alloys. Final report

International Nuclear Information System (INIS)

Schirra, M.; Falkenstein, A.; Heger, S.; Lapena, J.

2001-07-01

The creep rupture strength and creep experiments performed on low-activation OPTIFER alloys in the temperature range of 450-700 C shall be summarized in the present report. Together with the reference alloy of the type 9.5Cr1W-Mn-V-Ta, W-free variants (+Ge) with a more favorable activation and decay behavior shall be studied. Their smaller strength values are compensated by far better toughness characteristics. Of each development line, several batches of slightly varying chemical composition have been investigated over service lives of up to 40,000 h. Apart from the impact of a reference thermal treatment at a hardening temperature of 1075 C and an annealing temperature of 750 C, the influence of reduced hardening temperatures (up to 950 C) has been determined. A long-term use at increased temperatures (max. 550 C-20,000 h) produces an aging effect with strength being decreased in the annealed state. To determine this aging effect quantitatively, creep rupture experiments have been performed using specimens that were subjected to variable types of T/t annealing (550 -650 C, 330-5000 h). Based on all test results, minimum values for the 1% time-strain limit and creep rupture in the T range of 400-600 C can be given as design curves for 20,000 h. The minimum creep rates obtained from the creep curves recorded as a function of the experimental stress yield the stress exponent n (n=Norton) for the individual test temperatures. Creep behavior as a function of the test temperature yields the values for the effective activation energy of creeping Q K . The influence of a preceding temperature transient up to 800 C (≤Ac 1b ) or 840 C (>Ac 1b ) with subsequent creep rupture tests at 500 C and 550 C, respectively, shall be described. The results obtained for the OPTIFER alloys shall be compared with the results achieved for the Japanese 2% W-containing F82H-mod. alloy. (orig.) [de

Structural investigation of Fe(Cu)ZrB amorphous alloy

Energy Technology Data Exchange (ETDEWEB)

Duhaj, P. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Matko, I. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Svec, P. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Sitek, J. [Department of Nuclear Physics and Technology, Slovak Technical University, 81219 Bratislava (Slovakia); Janickovic, D. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav

1996-07-01

The crystallization process in Fe{sub 86}(Cu{sub 1})Zr{sub 7}B{sub 6} and Fe{sub 87}Zr{sub 7}B{sub 6} is investigated using the methods of transmission electron microscopy, electron and X-ray diffraction and resistometry. Two crystallization reactions take place during thermal annealing of amorphous Fe{sub 86}(Cu{sub 1})Zr{sub 7}B{sub 6} and Fe{sub 87}Zr{sub 7}B{sub 6} alloys. In both alloys the first crystallization begins with the formation of nanocrystalline {alpha}-Fe at temperature to approximately 800 K. The second crystallization starts above 1000 K; the nanocrystalline phase dissolves and together with the remaining amorphous matrix form rough grains of {alpha}-Fe and dispersed Fe{sub 23}Zr{sub 6} phases. From Moessbauer spectroscopy it seems that there exist two neighbourhoods of Fe atoms in the amorphous structure. One of them is characterized by low Zr content and is responsible for the high-field component of the hyperfine field distribution p(H). The second one is rich in Zr and B and is responsible for the low-field component of p(H). This is in accord with the observation of two crystallization steps separated by a large interval of temperatures due to the existence of two chemically different regions or clusters. (orig.)

Alloying behaviour of electroplated Ag film with its underlying Pd/Ti film stack for low resistivity interconnect metallization

International Nuclear Information System (INIS)

Ezawa, Hirokazu; Miyata, Masahiro; Tatsumi, Kohei

2014-01-01

Highlights: • Alloying behavior of Ag/Pd/Ti film stack was studied by annealing at 400-800 °C. • The Ag film resistivity decreased with increasing annealing temperature. • Formation of the Pd-Ti intermetallics was found to be dominant over Ag-Pd alloying. • The excess Ti was consumed to form Ti oxides, which inhibited Ti alloying with Ag. -- Abstract: In this paper, viability of electroplated Ag film into device application was studied. Alloying behavior of the Ag film with its underlying Pd(50 nm)/Ti(100 nm) film stack was investigated with respect to heat treatment at different temperatures from 400 °C to 800 °C in an argon ambient. After annealing at 400 °C, the electrical resistivity of the Ag film increased due to Pd alloying with Ag. Formation of Pd–Ti intermetallic phases became dominant over Ag–Pd alloying with increasing annealing temperature, leading to the resistivity decrease of the Ag film. The resistivity of the 800 °C annealed Ag film approached that of its as-plated Ag film. The excess Ti atoms which were not consumed to form the intermetallic phases with the Pd atoms migrated to the Ag film surface to form Ti oxides along the Ag grain boundaries on the topmost film surface. The Ag/Pd/Ti film stack has been confirmed to maintain the resistivity of the Ag film at as-plated low levels after high temperature annealing. This paper also discusses process integration issues to enable the Ag metallization process for future scaled and three dimensionally chip stacked devices

The effect of annealing temperature on the properties of powder metallurgy processed Ti-35Nb-2Zr-0.5O alloy.

Science.gov (United States)

Málek, Jaroslav; Hnilica, František; Veselý, Jaroslav; Smola, Bohumil; Medlín, Rostislav

2017-11-01

Ti-35Nb-2Zr-0.5O (wt%) alloy was prepared via a powder metallurgy process (cold isostatic pressing of blended elemental powders and subsequent sintering) with the primary aim of using it as a material for bio-applications. Sintered specimens were swaged and subsequently the influence of annealing temperature on the mechanical and structural properties was studied. Specimens were annealed at 800, 850, 900, 950, and 1000°C for 0.5h and water quenched. Significant changes in microstructure (i.e. precipitate dissolution or grain coarsening) were observed in relation to increasing annealing temperature. In correlation with those changes, the mechanical properties were also studied. The ultimate tensile strength increased from 925MPa (specimen annealed at 800°C) to 990MPa (900°C). Also the elongation increased from ~ 13% (800°C) to more than 20% (900, 950, and 1000°C). Copyright © 2017 Elsevier Ltd. All rights reserved.

Properties and application study of Inconel alloy tube made in China

International Nuclear Information System (INIS)

Yang Xiang; Su Xingwan; Wen Yan

1997-01-01

The mech-physical properties and the corrosion resistance properties of the SG tube of Inconel alloy made in China under any conditions are briefly presented, and the test and research for bending and expending the tubes have been performed. In the process of corrosion experiments the Inconel alloy tubes were compared with that of the same kind of materials made in foreign countries. The Inconel alloy tubes have better stress corrosion resistance cracking prosperities than Inconel 600 and Incoloy 800 when they were in the solutions which contained high concentrated chlorine ion and alkali at high temperature

Preliminary application of the draft code case for alloy 617 for a high temperature component

International Nuclear Information System (INIS)

Lee, Hyeong Yeon; Kim, Yong Wan; Song, Kee Nam

2008-01-01

The ASME draft Code Case for Alloy 617 was developed in the late 1980s for the design of very-high-temperature gas cooled reactors. The draft Code Case was patterned after the ASME Code Section III Subsection NH and was intended to cover Ni-Cr-Co-Mo Alloy 617 to 982 .deg. C (1800 .deg. F). But the draft Code Case is still in an incomplete status, lacking necessary material properties and design data. In this study, a preliminary evaluation on the creep-fatigue damage for a high temperature hot duct pipe structure has been carried out according to the draft Code Case. The evaluation procedures and results according to the draft Code Case for Alloy 617 material were compared with those of the ASME Subsection NH and RCC-MR for Alloy 800H material. It was shown that many data including material properties, fatigue and creep data should be supplemented for the draft Code Case. However, when the evaluation results on the creep-fatigue damage according to the draft Code Case, ASME-NH and RCC-MR were compared based on the preliminary evaluation, it was shown that the Alloy 617 results from the draft Code Case tended to be more resistant to the creep damage while less resistant to the fatigue damage than those from the ASME-NH and RCC-MR

Hydrogen interactions in aluminum-lithium alloys

Science.gov (United States)

Smith, S. W.; Scully, J. R.

1991-01-01

A program is described which seeks to develop an understanding of the effects of dissolved and trapped hydrogen on the mechanical properties of selected Al-Li-Cu-X alloys. A proposal is made to distinguish hydrogen (H2) induced EAC from aqueous dissolution controlled EAC, to correlate H2 induced EAC with mobile and trapped concentrations, and to identify significant trap sites and hydride phases (if any) through use of model alloys and phases. A literature review shows three experimental factors which have impeded progress in the area of H2 EAC for this class of alloys. These are as listed: (1) inter-subgranular fracture in Al-Li alloys when tested in the S-T orientation in air or vacuum make it difficult to readily detect H2 induced fracture based on straight forward changes in fractography; (2) the inherently low H2 diffusivity and solubility in Al alloys is further compounded by a native oxide which acts as a H2 permeation barrier; and (3) H2 effects are masked by dissolution assisted processes when mechanical testing is performed in aqueous solutions.

Stress corrosion cracking of nickel alloys in bicarbonate and chloride solutions

International Nuclear Information System (INIS)

Ares, A. E.; Carranza, R. M.; Giordano, C. M.; Zadorozne, N. S.; Rebak, R.B.

2013-01-01

Alloy 22 is one of the candidates for the manufacture of high level radioactive waste containers. These containers provide services in natural environments characterized by multi-ionics solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate at temperatures above 60°C and applied potentials around +400 mVSCE are necessary in order to produce cracking, . This susceptibility may be associated to the instability of the passive film formed and to the formation of an anodic current peak in the polarization curves in these media. Until now, it is unclear the role played by each alloying element (Ni, Cr or Mo) in the SCC susceptibility of Alloy 22 in these media The aim of this work is to evaluate the SCC susceptibility of nickel-based alloys in media containing bicarbonate and chloride ions, at high temperature. Slow Strain Rate Testing (SSRT) was conducted to samples of different alloys: 22 (Ni-Cr-Mo), 600 (Ni-Cr-Fe), 800H (Ni-Fe-Cr) y 201 (99.5% Ni).This tests were conducted in 1.1 mol/L NaHCO 3 +1.5 mol/L NaCl a 90°C and different applied potentials (+200mVSCE,+300 mVSCE, +400 mVSCE). These results were complemented with those obtained in a previous work, where we studied the anodic electrochemical behavior of nickel base alloys under the same conditions. It was found that alloy 22 showed a current peak in a potential range between +200 mVSCE and +300 mVSCE when immersed in bicarbonate ions containing solutions. This peak was attributed to the presence of chromium in the alloys. The SSRT showed that only alloy 22 has a clear indication of stress corrosion cracking. The current results suggested that the presence of an anodic peak in the polarization curves was not a sufficient condition for cracking. (author)

Flow behaviour of autoclaved, 20% cold worked, Zr-2.5Nb alloy pressure tube material in the temperature range of room temperature to 800 deg. C

International Nuclear Information System (INIS)

Dureja, A.K.; Sinha, S.K.; Srivastava, Ankit; Sinha, R.K.; Chakravartty, J.K.; Seshu, P.; Pawaskar, D.N.

2011-01-01

Pressure tube material of Indian Heavy Water Reactors is 20% cold-worked and stress relieved Zr-2.5Nb alloy. Inherent variability in the process parameters during the fabrication stages of pressure tube and also along the length of component have their effect on micro-structural and texture properties of the material, which in turn affect its strength parameters (yield strength and ultimate tensile strength) and flow characteristics. Data of tensile tests carried out in the temperature range from room temperature to 800 deg. C using the samples taken out from a single pressure tube have been used to develop correlations for characterizing the strength parameters' variation as a function of axial location along length of the tube and the test temperature. Applicability of Ramberg-Osgood, Holloman and Voce's correlations for defining the post yield behaviour of the material has been investigated. Effect of strain rate change on the deformation behaviour has also been studied.

Experimental Study on Dissimilar Friction Stir welding of Aluminium Alloys (5083-H111 and 6082-T6) to investigate the mechanical properties

Science.gov (United States)

Kumar, H. M. Anil; Venkata Ramana, V.; Pawar, Mayur

2018-03-01

Friction stir welding is an innovative technology in the joining realm of metals and alloys. This technique is highly economical and suitable especially for non ferrous alloys compared to ferrous alloys. It finds many applications in various fields of aeronautics, automobile, ship building industries etc. The paper presents the comparative results of mechanical properties such as tensile strength, microstructure, macro structure and hardness on the similar and dissimilar aluminum alloys AA5083-H111 and AA6082-T6 under certain selected variables - constant tool rotational speed, its tilt angle, welding speed using friction stir welding process. It is observed from the experimental results that joint efficiency of dissimilar aluminium alloys is higher than the similar aluminum alloys.

Comparison of high temperature, high frequency core loss and dynamic B-H loops of two 50 Ni-Fe crystalline alloys and an iron-based amorphous alloy

International Nuclear Information System (INIS)

Wieserman, W.R.; Schwarze, G.E.; Niedra, J.M.

1994-01-01

The availability of experimental data that characterizes the performance of soft magnetic materials for the combined conditions of high temperature and high frequency is almost non-existent. An experimental investigation was conducted over the temperature range of 23 to 300 C and frequency range of 1 to 50 kHz to determine the effects of temperature and frequency on the core loss and dynamic B-H loops of three different soft magnetic materials; an oriented-grain 50Ni-50Fe alloy, a nonoriented-grain 50Ni-50Fe alloy, and an iron-based amorphous material (Metglas 2605SC). A comparison of these materials show that the nonoriented-grain 50Ni-50Fe alloy tends to have either the lowest or next lowest core loss for all temperatures and frequencies investigated

Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

Directory of Open Access Journals (Sweden)

ZHU Xue-mei

2017-08-01

Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.

Effect of chemical composition of copper alloys on their hot-brittleness and weldability

International Nuclear Information System (INIS)

Zakharov, M.V.

1985-01-01

Effect of different alloying elements on the hot crack formation in argon-arc welding of M1 copper has been studied. It is shown that the effective crystallization interval has a determining influence on hot-brittleness of low-alloyed high-thermal- and electric conducting welded copper alloys. The narrow is this interval the lower is linear schrinkage and the alloys inclined to the formation of crystallization cracks in welding to a lesser degree. Alloying elements with low solubility in copper in solid state broadening the crystallization interval affect negatively the alloy hot-brittleness. Such additives as zirconium are useful at 0.02-0.O5% content and at > 0.1% content are intolerable. As to cadmium, tin, magnesium, cerium and antimony additives they don't practically strengthen copper and its alloys at 700-800 deg C and they should not be introduced

The effects of microstructure on the hydriding for 500 °C/2 h aged U-13at.%Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Ji, Hefei; Chen, Xianglin; Shi, Peng; Hu, Guichao; Li, Ruiwen [China Academy of Engineering Physics, Mianyang 621900 (China); Yang, Jiangrong, E-mail: yangjiangrong168@hotmail.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O.Box No.9-35, Huafengxincun, Jiangyou City, Sichuan Province, 621908 (China); Wang, Xiaolin, E-mail: xlwang@caep.cn [China Academy of Engineering Physics, Mianyang 621900 (China)

2017-05-15

The microstructure and hydriding properties of as-quenched and 500 °C/2 h aged U-13at.%Nb alloys were investigated. After suffering 500 °C/2 h process, the as-quenched alloy with single metastable α″ phase partially decomposed into lamellar pearlite along prior-γ grain boundaries and around impurities accompanied by the redistribution of niobium. The as-quenched U-13at.%Nb alloy performed perfect corrosion resistance to hydrogen while the aged poor owing to their different microstructure. The hydriding reaction order for the aged alloy in this work was determined to be 0.62. The decomposed areas had relatively lower Volta potential than the non-decomposed areas, which decreased the hydrogen corrosion resistance. In addition, the conclusion that Nb-poor α-like-U reacted with hydrogen preferentially than Nb-rich phase was confirmed by KFM results that Nb-poor phase had relatively lower Volta potential.

Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired Mechanical and Corrosion Properties.

Energy Technology Data Exchange (ETDEWEB)

Dulikravich, George S.; Sikka, Vinod K.; Muralidharan, G.

2006-06-01

The goal of this project was to adapt and use an advanced semi-stochastic algorithm for constrained multiobjective optimization and combine it with experimental testing and verification to determine optimum concentrations of alloying elements in heat-resistant and corrosion-resistant H-series stainless steel alloys that will simultaneously maximize a number of alloy's mechanical and corrosion properties.

Experimental study of the electric resistivity in Heusler alloys

International Nuclear Information System (INIS)

Kunzler, J.V.

1980-01-01

Electrical resistivity measurements have been performed in the Cu 2 Mn (A1sub(1-x) Snsub(x)) Heusler alloys, where x = 0, 0.05, 0.10 and 0.15, in the temperature range from 4.2 to 800 0 K. Measurements have also been made on the Ni 2 MnX Heusler asloys, with X = In, Sn or Sb, in the range from 4.2 to 300 0 K. The experimental curves clearly show the importance of the ferromagnetic character for the alloys resistivity. The results obtained for the copper alloys, as well as for the Ni 2 MnSn alloy, are in agreement with an interpretation in terms of Bloch-Gruneisen and spin-disorder models, and fail to provide evidences of s-d scattering for the conduction electrons. This is not the case for the Ni 2 MnIn and Ni 2 MnSb alloys, in which the presence of (s-d) interband electronic scattering process, via phonon, was detected. Specially for the two last alloys specific heat and electronic photo-emissivity experiments are suggested. (Author) [pt

Microstructure, transformation behavior and mechanical properties of a (Ti{sub 50}Ni{sub 38}Cu{sub 12}){sub 93}Nb{sub 7} alloy

Energy Technology Data Exchange (ETDEWEB)

Jiang, Daqiang, E-mail: daqiang.jiang@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Department of Materials Science and Engineering, China University of Petroleum, Beijing (China); Liu, Yinong [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Liu, Weilong; Song, Lixie; Jiang, Xiaohua [Department of Materials Science and Engineering, China University of Petroleum, Beijing (China); Yang, Hong [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Cui, Lishan [Department of Materials Science and Engineering, China University of Petroleum, Beijing (China)

2015-03-11

A (Ti{sub 50}Ni{sub 38}Cu{sub 12}){sub 93}Nb{sub 7} alloy is fabricated by arc melting, forging and drawing. The microstructure, transformation behavior and mechanical properties were investigated by means of scanning electron microscope (SEM), differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA) and tensile test machine. SEM observation showed that the as cast alloy is composed of TiNiCu and Nb-rich phases. After drawing, the alloy showed single step transformations during heating and cooling within the whole annealing temperature range from 400 °C to 800 °C. With the increase of the annealing temperature, both the transformation temperatures and the damping capacity increased first and then decreased. The ultimate strength of the alloy after annealing at 400 °C is over 1500 MPa and the maximum elongation of the alloy after annealing at 800 °C is more than 20%.

Thermal Effects That Arise upon Different Heat Treatments in Austenitic Steels Alloyed with Titanium and Phosphorus

Science.gov (United States)

Arbuzov, V. L.; Berger, I. F.; Bobrovskii, V. I.; Voronin, V. I.; Danilov, S. E.; Kazantsev, V. A.; Kataev, N. V.; Sagaradze, V. V.

2018-04-01

Structural and microstructural changes that arise in the course of the heat treatment of Cr-Ni-Mo austenitic stainless steels with different concentrations of titanium and phosphorus have been studied. It has been found that the alloying with phosphorus decreases the lattice parameter of these steels. The phosphorus contribution to this effect is 0.015 ± 0.002 Å/at %. Aging at a temperature of 670 K for about 20 h leads to the precipitation of dispersed needle-like particles, which are most likely to be iron phosphides. In the temperature range of 700-800 K, in austenitic steels, the atomic separation of the solid solution occurs, the intensity of which decreases upon alloying with titanium or phosphorus at concentrations of 1.0 and 0.1 wt %, respectively. At higher temperatures (about 950 K), the formed precipitates of the Ni3Ti (γ') phase increase in size to 7-10 nm.

Thermal cycling influence on microstructural characterization of alloys with high nickel content

International Nuclear Information System (INIS)

Abrudeanu, M.; Gradin, O.; Vulpe, S. C.; Ohai, D.

2013-01-01

The IV nuclear energy generation systems are aimed at making revolutionary improvements in economics, safety and reliability, and sustainability. To achieve these goals, Generation IV systems will operate at higher temperatures and in higher radiation fields. This paper shows the thermal cycling influences on microstructure and hardness of nickel based alloys: Incoloy 800 HT and Inconel 617. These alloys were meekly at a thermal cycling of 25, 50, 75 and 100 cycles. The temperature range of a cycle was between 400 O C and 700 O C. Nickel base alloys develop their properties by solid solution and/or precipitation strengthening. (authors)

Introduction to hydrogen in alloys

International Nuclear Information System (INIS)

Westlake, D.G.

1980-01-01

Substitutional alloys, both those that form hydrides and those that do not, are discussed, but with more emphasis on the former than the latter. This overview includes the following closely related subjects: (1) the significant effects of substitutional solutes on the pressure-composition-temperature (PCT) equilibria of metal-hydrogen systems, (2) the changes in thermodynamic properties resulting from differences in atom size and from modifications of electronic structure, (3) attractive and repulsive interactions between H and solute atoms and the effects of such interactions on the pressure dependent solubility for H, (4) H trapping in alloys of Group V metals and its effect on the terminal solubility for H (TSH), (5) some other mechanisms invoked to explain the enhancement (due to alloying) of the (TSH) in Group V metals, and (6) H-impurity complexes in alloys of the metals Ni, Co, and Fe. Some results showing that an enhanced TSH may ameliorate the resistance of a metal to hydrogen embrittlement are presented

Microstructural characterization and electrochemical corrosion behavior of Incoloy 800 in sulphate and chloride solutions

International Nuclear Information System (INIS)

Mansur, Fabio Abud; Schvartzman, Monica Maria de Abreu Mendonca; Campos, Wagner Reis da Costa; Aguiar, Antonio Eugenio de; Chaim, Marcos Souza

2011-01-01

Corrosion has been the major cause of tube failures in steam generators (SG) tubes in nuclear power plants. Problems have resulted from impurities in the secondary water systems which are originated from leaks of cooling water. It is important to understand the compatibility of steam generator tube materials with the environment. This study presents the microstructural characterization and electrochemical behavior of the Incoloy 800 in sodium chloride and sodium sulphate aqueous solutions at 80 degree C. Potentiodynamic anodic polarization, cyclic polarization and open circuit potential (OCP) measurements were the electrochemical techniques applied in this work. The pitting resistance of Incoloy 800 in chloride plus sulphate mixtures were also examined. Experiments performed in solutions with different concentrations of Cl- and SO 4 2- ions in solution (200 ppb, 500 ppb, 1ppm, 5 ppm, 50 ppm and 100 ppm) showed that this concentrations range had no substantial effect on the anodic behavior of the alloy. After polarization no localized corrosion was found on the samples. (author)

Influence of sulfate ion concentration and pH on the corrosion of Mg-Al-Zn-Mn (GA9 magnesium alloy

Directory of Open Access Journals (Sweden)

Sudarshana Shetty

2015-09-01

Full Text Available The corrosion behavior of Mg-Al-Zn-Mn (GA9 alloy in sodium sulfate solutions was studied over a range of concentrations and solution temperatures at different pH conditions by electrochemical techniques like Tafel extrapolation and electrochemical impedance spectroscopy (EIS. The studies were carried out in solutions with sodium sulfate concentrations 0.1M, 0.5M, 1M, 1.5M and 2M; and at five different temperatures of 30, 35, 40, 45 and 50 °C in a pH range of 3–12. As per the experimental data, the corrosion rate of the alloy increased with the increase in temperature, and also with the increase in concentration of sodium sulfate in the medium. It was observed that the rate of corrosion decreased with the increase in pH. The activation parameters like activation energy, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the alloy was examined before and after corrosion using scanning electron microscopy (SEM.

31 CFR 800.509 - Materiality.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Materiality. 800.509 Section 800.509 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF INVESTMENT... FOREIGN PERSONS Committee Procedures: Review and Investigation § 800.509 Materiality. The Committee...

Influence of deformation conditions on texture formation and ductility in titanium alloys under hydrostatic pressure

International Nuclear Information System (INIS)

Dekun, A.M.; Kushakevich, S.A.; Adamesku, R.A.; Khmelinin, Yu.F.; Beresnev, B.I.; Shishmintsev, V.F.

1982-01-01

The influence of hot pressing parameters on microstructure, texture and mechanical properties of bars from titanium alloys VT1-0, VT5-1, (α-alloys) and VT3-1 (α+ν-alloy) has been investigated. Mechanical testing of samples has been performed under hydrostatic pressure from 200 to 800 MPa. It is shown that the temperature, deformation degree and type of the structure obtained exert a slight effect on mechanical properties of bars. The texture heterogeneity is more pronounced in α-alloys. It has been found that hydrostatic pressure during sample tensile testing improves their ductility characteristics

Effect of Microstructure and Alloy Chemistry on Hydrogen Embrittlement of Precipitation-Hardened Ni-Based Alloys

Science.gov (United States)

Obasi, G. C.; Zhang, Z.; Sampath, D.; Morana, Roberto; Akid, R.; Preuss, M.

2018-04-01

The sensitivity to hydrogen embrittlement (HE) has been studied in respect of precipitation size distributions in two nickel-based superalloys: Alloy 718 (UNS N07718) and Alloy 945X (UNS N09946). Quantitative microstructure analysis was carried out by the combination of scanning and transmission electron microscopy and energy dispersive x-ray spectroscopy (EDS). While Alloy 718 is mainly strengthened by γ″, and therefore readily forms intergranular δ phase, Alloy 945X has been designed to avoid δ formation by reducing Nb levels providing high strength through a combination of γ' and γ″. Slow strain rate tensile tests were carried out for different microstructural conditions in air and after cathodic hydrogen (H) charging. HE sensitivity was determined based on loss of elongation due to the H uptake in comparison to elongation to failure in air. Results showed that both alloys exhibited an elevated sensitivity to HE. Fracture surfaces of the H precharged material showed quasi-cleavage and transgranular cracks in the H-affected region, while ductile failure was observed toward the center of the sample. The crack origins observed on the H precharged samples exhibited quasi-cleavage with slip traces at high magnification. The sensitivity is slightly reduced for Alloy 718, by coarsening γ″ and reducing the overall strength of the alloy. However, on further coarsening of γ″, which promotes continuous decoration of grain boundaries with δ phase, the embrittlement index rose again indicating a change of hydrogen embrittlement mechanism from hydrogen-enhanced local plasticity (HELP) to hydrogen-enhanced decohesion embrittlement (HEDE). In contrast, Alloy 945X displayed a strong correlation between strength, based on precipitation size and embrittlement index, due to the absence of any significant formation of δ phase for the investigated microstructures. For the given test parameters, Alloy 945X did not display any reduced sensitivity to HE compared with

Oxidation properties of laser clad Nb-Al alloys

International Nuclear Information System (INIS)

Tewari, S.K.; Mazumder, J.

1992-01-01

This paper reports on laser cladding parameters for non-equilibrium synthesis for several ternary and complex Nb-Al base alloys containing Ti, Cr, Si, Ni, B and C that have been established. Phase transformations occurring below 1500 degrees C have been determined using differential thermal analysis. Ductility of the clads is qualitatively evaluated from the extent of cracking around the microhardness indentations. Oxidation resistance of the clads in flowing air is measured at 800 degrees C, 1200 degrees C and 1400 degrees C and parabolic rate constants are calculated. Microstructure of the clads is studied using optical and scanning electron microscopes. X-ray diffraction and EDX techniques are used for identification of the oxides formed and the phases formed in as clad material. Oxide morphology is studied using SEM. Effect of alloying additions on the ductility and oxidation resistance of the laser clad Nb-Al alloys is discussed. The results are compared with those reported in literature for similar alloys produced by conventional processing methods

49 CFR 800.2 - Organization.

Science.gov (United States)

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Organization. 800.2 Section 800.2 Transportation... ORGANIZATION AND FUNCTIONS OF THE BOARD AND DELEGATIONS OF AUTHORITY Organization and Functions § 800.2 Organization. The Board consists of five Members appointed by the President with the advice and consent of the...

Oxidation behaviour of bulk W-Cr-Ti alloys prepared by mechanical alloying and HIPing

Energy Technology Data Exchange (ETDEWEB)

García-Rosales, C., E-mail: cgrosales@ceit.es [CEIT and Tecnun (University of Navarra), E-20018 San Sebastian (Spain); López-Ruiz, P.; Alvarez-Martín, S.; Calvo, A.; Ordás, N. [CEIT and Tecnun (University of Navarra), E-20018 San Sebastian (Spain); Koch, F.; Brinkmann, J. [Max-Planck-Institut für Plasmaphysik (IPP), EURATOM Association, D-85748 Garching (Germany)

2014-10-15

Self-passivating tungsten based alloys are expected to provide a major safety advantage compared to pure tungsten when used as first wall armour of future fusion reactors, due to the formation of a protective oxide scale, preventing the formation of volatile and radioactive WO{sub 3} in case of a loss of coolant accident with simultaneous air ingress. In this work results of isothermal oxidations tests at 800 and 1000 °C on bulk alloy WCr12Ti2.5 performed by thermogravimetric analysis (TGA) and by exposure to flowing air in a furnace are presented. In both cases a thin, dense Cr{sub 2}O{sub 3} layer is found at the outer surface, below which a Cr{sub 2}WO{sub 6} scale and Ti{sub 2}CrO{sub 5} layers alternating with WO{sub 3} are formed. The Cr{sub 2}O{sub 3}, Cr{sub 2}WO{sub 6} and Ti{sub 2}CrO{sub 5} scales act as protective barriers against fast inward O{sup 2−} diffusion. The oxidation kinetics seems to be linear for the furnace exposure tests while for the TGA tests at 800 °C the kinetics is first parabolic, transforming into linear after an initial phase. The linear oxidation rates are 2–3 orders of magnitude lower than for pure W.

Microstructure and properties of step aged rare earth alloy magnets

International Nuclear Information System (INIS)

Mishra, R.K.; Thomas, G.; Yoneyama, T.; Fukuno, A.; Ojima, T.

1980-11-01

Alloys with compositions Co-25.5 wt/o Sm-8 w/o Cu-15 w/o Fe-3 w/o Zr and Co-Sm-Cu-Fe-1.5 w/o Zr have been step aged to produce magnets with coercive force (iHc) in the range of 10 to 25k0e. The high coercive force magnets are typically aged at 800 to 850 0 C for 10 to 30 hours following the solution treatment at 1150 0 C. Subsequently, these are step aged to produce materials with high coercivity. The microstructure in all these alloys has a 2 phase cellular morphology with 2:17 phase surrounded by a 1:5 boundary phase. The long aging treatments at 800 to 850 0 C lead to coarsening of the two phase structure. The subsequent step-aging does not change the morphology, but only changes the chemical composition of the two phases. Best properties are obtained in materials with a coherent microstructure of optimum boundary phase thickness and optimum chemical composition. The highest values of iHc obtained so far are approx. 26k0e and approx. 16 k0e for the 3% Zr and 1.5% Zr alloys respectively. The best hard magnetic properties of (BH) max = 33 MG0e and iHc = 13k0e are for a 25% Sm-20% Fe-4 Cu-2% Zr alloy

Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

International Nuclear Information System (INIS)

Diaz Barriga Arceo, L.; Orozco, E.; Mendoza-Leon, H.; Palacios Gonzalez, E.; Leyte Guerrero, F.; Garibay Febles, V.

2007-01-01

Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 o C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 μm in length were obtained after heating at 800 o C, by means of this process

Nanostructures obtained from a mechanically alloyed and heat treated molybdenum carbide

Energy Technology Data Exchange (ETDEWEB)

Diaz Barriga Arceo, L. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico) and ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Orozco, E. [Instituto de Fisica UNAM, Apdo Postal 20-364, C.P. 01000 D.F. Mexico (Mexico)]. E-mail: eorozco@fisica.unam.mx; Mendoza-Leon, H. [ESIQIE-UPALM, IPN Apdo Postal 118-395, C.P. 07051 D.F. Mexico (Mexico)]. E-mail: luchell@yahoo.com; Palacios Gonzalez, E. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: epalacio@imp.mx; Leyte Guerrero, F. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: fleyte@imp.mx; Garibay Febles, V. [Programa de Ingenieria Molecular, I.M.P. Lazaro Cardenas 152, C.P. 07730 D.F. Mexico (Mexico)]. E-mail: vgaribay@imp.mx

2007-05-31

Mechanical alloying was used to prepare molybdenum carbide. Microstructural characterization of samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Molybdenum carbide was heated at 800 {sup o}C for 15 min in order to produce carbon nanotubes. Nanoparticles of about 50-140 nm in diameter and nanotubes with diameters of about 70-260 nm and 0.18-0.3 {mu}m in length were obtained after heating at 800 {sup o}C, by means of this process.

10 CFR 800.301 - Monitoring.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Monitoring. 800.301 Section 800.301 Energy DEPARTMENT OF ENERGY LOANS FOR BID OR PROPOSAL PREPARATION BY MINORITY BUSINESS ENTERPRISES SEEKING DOE CONTRACTS AND ASSISTANCE Loan Administration § 800.301 Monitoring. The Secretary shall have the right to audit any and all...

10 CFR 800.304 - Default.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Default. 800.304 Section 800.304 Energy DEPARTMENT OF... ASSISTANCE Loan Administration § 800.304 Default. (a) In the event that the borrower fails to perform the terms and conditions of the loan, the borrower shall be in default and the Secretary shall have the...

Tribological evaluation of surface modified H13 tool steel in warm forming of Ti–6Al–4V titanium alloy sheet

OpenAIRE

Wang, Dan; Li, Heng; Yang, He; Ma, Jun; Li, Guangjun

2014-01-01

The H13 hot-working tool steel is widely used as die material in the warm forming of Ti–6Al–4V titanium alloy sheet. However, under the heating condition, severe friction and lubricating conditions between the H13 tools and Ti–6Al–4V titanium alloy sheet would cause difficulty in guaranteeing forming quality. Surface modification may be used to control the level of friction force, reduce the friction wear and extend the service life of dies. In this paper, four surface modification methods (c...

Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

International Nuclear Information System (INIS)

Sungkono; Siti Aidah

2015-01-01

Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

Grain Refinement of Al-Si-Fe-Cu-Zn-Mn Based Alloy by Al-Ti-B Alloy and Its Effect on Mechanical Properties.

Science.gov (United States)

Yoo, Hyo-Sang; Kim, Yong-Ho; Jung, Chang-Gi; Lee, Sang-Chan; Lee, Seong-Hee; Son, Hyeon-Taek

2018-03-01

We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

Oxidation Behavior of Some Cr Ferritic Steels for High Temperature Fuel Cells

International Nuclear Information System (INIS)

Mohamed, H.E.

2012-01-01

The oxidation behavior of three high Cr ferritic steels designated 1Al, RA and 5Al with different levels of Al, Si, Mn and Hf has been investigated in the present work. These steels have been developed as candidates for Solid Oxide Fuel Cell (SOFC) interconnect. Specimens of these alloys have been subjected to isothermal as well as cyclic oxidation in air. Isothermal oxidation tests are conducted in the temperature range 800 - 1000 degree C for time periods up to 1000 h. cyclic oxidation tests were carried out at 800 and 1000 degree C for twenty 25 - h cycles giving a total cyclic exposure time of 500 h. The growth rate of the oxide scales was found to follow a parabolic law over a certain oxidation period which changed with alloy composition and oxidation temperature. The value of the parabolic rate constant increased with increasing oxidation temperature. At 800 and 900 degree C alloy 1Al exhibited higher oxidation resistance compared to the other two alloys. Alloy RA showed spalling behavior when oxidized at 900 degree C and the extent of spalling increased with increasing the oxidation temperature to 1000 degree C. Alloy 5Al oxidized at 1000 degree C showed the highest oxidation resistance among the investigated alloys. Alloy 1Al and RA showed similar scale morphology and composition. X- ray diffraction analysis revealed that the scales developed on these alloys consist of Cr 2 O 3 with an outer layer of MnCr 2 O 4 and a minor amount of FeCr 2 O 4 spinels. Alloy 5Al developed scale consisting of γ- Al 2 O 3 at 800 degree C and γ and α- Al 2 O 3 at 900 degree C. Oxidation of alloy 5Al at 1000 degree C led to formation of a scale consisting mainly of the protective phase α Al 2 O 3 . The presence of 0.84 wt% Al and 0.95 wt % Si in alloy 1Al enhanced its oxidation resistance compared to alloy RA which contains only 0.29 wt% Si and is Al - free. This enhancement was attributed to formation of internal oxidation zone in alloy 1Al just beneath the oxide / alloy

The Influence of Chemical Alloying on the High Temperature Wear Resistance of H-Free DLC Coatings

NARCIS (Netherlands)

Galvan, D.; Pei, Y.T.; Hosson, J.T.M. De; Cavaleiro, A.; Chandra, T; Tsuzaki, K; Militzer, M; Ravindran, C

2007-01-01

A commercial RF-sputtering deposition rig was employed to deposit H-free diamond-like carbon (DLC) coatings. The influence of alloying elements such as Ti and Si on the structure, mechanical and tribological properties of the coatings was investigated. The coating was observed in cross section and

Mössbauer and XRD study of the Fe65Si35 alloy obtained by mechanical alloying

International Nuclear Information System (INIS)

Vélez, G. Y.; Rodríguez, R. R.; Melo, C. A.; Pérez Alcázar, G. A.; Zamora, Ligia E.; Tabares, J. A.

2011-01-01

A study was made on the alloy Fe 65 Si 35 using x-ray diffraction and Mössbauer spectrometry. The alloy was obtained by mechanical alloying in a high energy planetary mill, with milling times of 15, 30, 50, 75 and 100 h. The results show that in the alloys two structural phases are present, a Fe-Si BCC disordered phase and ferromagnetic, and a Fe-Si SC phase, whose nature is paramagnetic and which decreases with milling time. In the temporal evolution of the milling two stages are differentiated: one between 15 and 75 h of milling, in which silicon atoms diffuse into the bcc matrix of iron and its effect is to reduce the hyperfine magnetic field; the other, after 75 h of milling, where the alloy is consolidated, the effect of the milling is only to increase the disorder of the system, increasing the magnetic order.

Characterization of Dispersion Strengthened Copper Alloy Prepared by Internal Oxidation Combined with Mechanical Alloying

Science.gov (United States)

Zhao, Ziqian; Xiao, Zhu; Li, Zhou; Zhu, Mengnan; Yang, Ziqi

2017-11-01

Cu-3.6 vol.% Al2O3 dispersion strengthened alloy was prepared by mechanical alloying (MA) of internal oxidation Cu-Al powders. The lattice parameter of Cu matrix decreased with milling time for powders milled in argon, while the abnormal increase of lattice parameter occurred in the air resulting from mechanochemical reactions. With a quantitative analysis, the combined method makes residual aluminum oxidized completely within 10-20 h while mechanical alloying method alone needs longer than 40 h. Lamellar structure formed and the thickness of lamellar structure decreased with milling time. The size of Al2O3 particles decreased from 46 to 22 nm after 40 h milling. After reduction, core-shell structure was found in MAed powders milled in the air. The compacted alloy produced by MAed powders milled in the argon had an average hardness and electrical conductivity of 172.2 HV and 82.1% IACS while the unmilled alloy's were 119.8 HV and 74.1% IACS due to the Al2O3 particles refinement and residual aluminum in situ oxidization.

Mechanical behaviour of Nd-Fe-B alloys in the semi-solid state

International Nuclear Information System (INIS)

Oliveira, I.L.; Sinka, V.; Ferrante, M.

1996-01-01

Two alloys with composition Nd 17.6 Fe 75.3 B1.2 Cu 5.9 and Nd 15.9 Fe 77.7 B 5 Cu 1.4 were vacuum induction melted and cast into cylindrical ingots. Samples with 12.3 and 13 mm diameter were deformed with different rates and deformation ratios. One alloy was deformed at 800 deg C between two parallel disks under constant load. Results show that these alloys behave as no-Newtonian fluids. This fact gives a better understanding of both magnetic and crystallographic texture development. Also, changes were detected in the behaviour of semisolid in the course of deformation. (author)

Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution.

Science.gov (United States)

Mareci, D; Bolat, G; Izquierdo, J; Crimu, C; Munteanu, C; Antoniac, I; Souto, R M

2016-03-01

Biodegradable magnesium-calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg-0.63Ca and Mg-0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural instabilities of high temperature alloys and their use in advanced high temperature gas cooled reactors

International Nuclear Information System (INIS)

Schuster, H.; Ennis, P.J.; Nickel, H.; Czyrska-Filemonowicz, A.

1989-01-01

High-temperature, iron-nickel and nickel based alloys are the candidate heat exchanger materials for advanced high temperature gas-cooled reactors supplying process heat for coal gasification, where operation temperatures can reach 850-950 deg. C and service lives of more than 100,000 h are necessary. In the present paper, typical examples of structural changes which occur in two representative alloys (Alloy 800 H, Fe-32Ni-20Cr and Alloy 617, Ni-22Cr-12Co-9Mo-1Al) during high temperature exposure will be given and the effects on the creep rupture properties discussed. At service temperatures, precipitation of carbides occurs which has a significant effect on the creep behaviour, especially in the early stages of creep when the precipitate particles are very fine. During coarsening of the carbides, carbides at grain boundaries restrict grain boundary sliding which retards the development of creep damage. In the service environments, enhanced carbide precipitation may occur due to the ingress of carbon from the environment (carburization). Although the creep rate is not adversely affected, the ductility of the carburized material at low and intermediate temperatures is very low. During simulated service exposures, the formation of surface corrosion scales, the precipitation of carbides and the formation of internal oxides below the surface leads to depletion of the matrix in the alloying elements involved in the corrosion processes. In thin-walled tubes the depletion of Cr due to Cr 2 O 3 formation on the surface can lead to a loss of creep strength. An additional depletion effect resulting from environmental-metal reactions is the loss of carbon (decarburization) which may occur in specific environments. The compositions of the cooling gases which decarburize the material have been determined; they are to be avoided during reactor operation

Study of the oxidation of Fe-Cr alloys at high temperatures

International Nuclear Information System (INIS)

Carneiro, J.F.; Sabioni, A.C.S.

2010-01-01

The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1μg. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10 -9 g 2 .cm -4 .s -1 , for the alloy Fe-1.5% Cr, to 1.18 x 10-14g 2 .cm -4 .s -1 for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

Effects of silicon on mechanical properties of AM60 magnesium alloy

Directory of Open Access Journals (Sweden)

Hu Yong

2012-08-01

Full Text Available Silicon was added to improve the tensile, wear and creep behaviors of AM60 magnesium alloy in this study. The investigation has been undertaken by means of universal testing machine, HBE-3000A Brinell hardness tester, M-2000 friction-wear machine, DMA-Q800 creep machine, optical microscopy (OM and scanning electron microscopy (SEM. The results indicate that the Chinese script type Mg2Si particles are formed by adding Si into the AM60 magnesium alloy. The ultimate tensile strength and hardness of the AM60 magnesium alloy increases with the Si addition, and the ultimate tensile strength and hardness of the AM60+1.0wt.%Si alloy are increased by 12% and 19.8%, respectively in comparison with that of the AM60 magnesium alloy. The wear property and the high temperature creep property of the AM60 magnesium alloy are also improved with Si addition. The wear mechanisms of the AM60 and AM60+1.0wt.%Si alloys are adhesive wear and abrasion wear, respectively. While, the elongation of the AM60 magnesium alloy decreases with the addition of Si. The optimum Si addition content is 1.0wt.%.

Nonequilibrium synthesis of Nb-Al alloys by laser processing

International Nuclear Information System (INIS)

Tewari, S.K.; Mazumder, J.

1993-01-01

The technique of laser surface modification provides a unique means of synthesizing novel nonequilibrium materials in near net shape. Claddings of several NbAl 3 alloys with Ti, B and Hf as a ternary alloy addition were prepared using a CW CO 2 laser. Isothermal oxidation behavior of the clads were examined in air. Oxidation tests at 800, 1,200 and 1,400 C. Alternating layers of alumina and NbAlO 4 were not observed in any of the samples as reported in literature for conventionally processed NbAl 3 oxidized under similar conditions. The parabolic rate constants for all the alloys, except 0 B, were comparable to that for isothermal oxidation of β-NiAl, at 1,200 and 1,400 C in 0.1 atm oxygen, which is a known alumina former. Ternary alloying additions for improved oxidation resistance at 1,400 C accompanied with improved ductility were identified

Structural and magnetic properties of nanocrystalline Fe–Co–Ni alloy processed by mechanical alloying

International Nuclear Information System (INIS)

Raanaei, Hossein; Eskandari, Hossein; Mohammad-Hosseini, Vahid

2016-01-01

In this present work, a nanostructured iron–cobalt–nickel alloy with Fe_5_0Co_3_0Ni_2_0 composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe_3O_4 crystalline phase. - Highlights: • This article focuses on mechanical alloying of Fe_5_0Co_3_0Ni_2_0 composition. • Structural and magnetic properties were investigated. • Saturation magnetization was increased sharply after 16 h of milling time. • The heat treatment revealed the signature of Fe_3O_4 as well as FeNi_3 and Co crystalline phases.

Structural and magnetic properties of nanocrystalline Fe–Co–Ni alloy processed by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Raanaei, Hossein, E-mail: hraanaei@yahoo.com [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Eskandari, Hossein [Department of Mechanical Engineering, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Mohammad-Hosseini, Vahid [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of)

2016-01-15

In this present work, a nanostructured iron–cobalt–nickel alloy with Fe{sub 50}Co{sub 30}Ni{sub 20} composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe{sub 3}O{sub 4} crystalline phase. - Highlights: • This article focuses on mechanical alloying of Fe{sub 50}Co{sub 30}Ni{sub 20} composition. • Structural and magnetic properties were investigated. • Saturation magnetization was increased sharply after 16 h of milling time. • The heat treatment revealed the signature of Fe{sub 3}O{sub 4} as well as FeNi{sub 3} and Co crystalline phases.

Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution

Energy Technology Data Exchange (ETDEWEB)

Mareci, D., E-mail: danmareci@yahoo.com [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Bolat, G. [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Izquierdo, J. [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Crimu, C.; Munteanu, C. [Faculty of Mechanical Engineering, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Antoniac, I. [Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania); Souto, R.M., E-mail: rsouto@ull.es [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania)

2016-03-01

Biodegradable magnesium–calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg–0.63Ca and Mg–0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. - Highlights: • Spontaneous degradation of MgCa alloys in Ringer's solution characterized at 37 °C • Reactivity differences between Mg0.63Ca and Mg0.89Ca are evidenced using multiscale electrochemical characterization. • Electrochemical activation occurs heterogeneously on the alloy surface. • Metal dissolution is accompanied by local pH changes. • Mg0.63Ca degrades faster

Nickel alloys and high-alloyed special stainless steels. Properties, manufacturing, applications. 4. compl. rev. ed.

International Nuclear Information System (INIS)

Heubner, Ulrich; Kloewer, Jutta; Alves, Helena; Behrens, Rainer; Schindler, Claudius; Wahl, Volker; Wolf, Martin

2012-01-01

This book contains the following eight topics: 1. Nickel alloys and high-alloy special stainless steels - Material overview and metallurgical principles (U. Heubner); 2. Corrosion resistance of nickel alloys and high-alloy special stainless steels (U. Heubner); 3. Welding of nickel alloys and high-alloy special stainless steels (T. Hoffmann, M. Wolf); 4. High-temperature materials for industrial plant construction (J. Kloewer); 5. Nickel alloys and high-alloy special stainless steels as hot roll clad composites-a cost-effective alternative (C. Schindler); 6. Selected examples of the use of nickel alloys and high-alloy special stainless steels in chemical plants (H. Alves); 7. The use of nickel alloys and stainless steels in environmental engineering (V. Wahl); 8: Nickel alloys and high-alloy special stainless steels for the oil and gas industry (R. Behrens).

Fabrication and Characterization of novel W80Ni10Nb10 alloy produced by mechanical alloying

Science.gov (United States)

Saxena, R.; Patra, A.; Karak, S. K.; Pattanaik, A.; Mishra, S. C.

2016-02-01

Nanostructured tungsten (W) based alloy with nominal composition of W80Ni10Nb10 (in wt. %) was synthesized by mechanical alloying of elemental powders of tungsten (W), nickel (Ni), niobium (Nb) in a high energy planetary ball-mill for 20 h using chrome steel as grinding media and toluene as process control agent followed by compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h in Ar atmosphere. The phase evolution and the microstructure of the milled powder and consolidated product were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The crystallite size of W in W80Ni10Nb10 powder was reduced from 100 μm at 0 h to 45.6 nm at 10 h and 34.1 nm at 20 h of milling whereas lattice strain increases to 35% at 20 h of milling. The dislocation density shows sharp increase up to 5 h of milling and the rate of increase drops beyond 5 to 20 h of milling. The lattice parameter of tungsten in W80Ni10Nb10 expanded upto 0.04% at 10 h of milling and contracted upto 0.02% at 20 h of milling. The SEM micrograph revealed the presence of spherical and elongated particles in W80Ni10Nb10 powders at 20 h of milling. The particle size decreases from 100 μm to 2 μm with an increase in the milling time from 0 to 20 hours. The crystallite size of W in milled W80Ni10Nb10 alloy as evident from bright field TEM image was in well agreement with the measured crystallite size from XRD. Structure of W in 20 h milled W80Ni10Nb10 alloy was identified by indexing of selected area diffraction (SAD) pattern. Formation of NbNi intermetallic was evident from XRD pattern and SEM micrograph of sintered alloy. Maximum sinterability of 90.8% was achieved in 20 h milled sintered alloy. Hardness and wear study was also conducted to investigate the mechanical behaviour of the sintered product. Hardness of W80Ni10Nb10 alloy reduces with increasing load whereas wear rate increases with increasing load. The evaluated

Hydrogen diffusion in Mg–H and Mg–Ni–H alloys

Czech Academy of Sciences Publication Activity Database

Čermák, Jiří; Král, Lubomír

2008-01-01

Roč. 56, č. 12 (2008), s. 2677-2686 ISSN 1359-6454 R&D Projects: GA ČR GA106/07/0010 Institutional research plan: CEZ:AV0Z20410507 Keywords : intermetallic compounds * magnesium alloys * hydrogen-storage materials Subject RIV: BJ - Thermodynamics Impact factor: 3.729, year: 2008

Study of the oxidation kinetics of the nickel-molybdenum alloy

International Nuclear Information System (INIS)

Gouillon, Marie-Josephe

1974-01-01

This research thesis reports the study of the oxidation of a nickel-molybdenum alloy in the high-nickel-content part of this alloy. After a bibliographical study on the both metals, the author proposes a physical model based on observed phenomena and based on experimental results. Based on a thermodynamic study, the author compares the stability of the different oxides which may be formed, and reports a prediction of oxides obtained on the alloy during oxidation. Qualitative and quantitative studies have been performed by scanning electron microscopy coupled with electronic microprobe analysis to investigate morphological characteristics on oxidation films. A kinetic study by thermogravimetry shows a decrease of the alloy oxidation rate with respect to that of pure nickel at temperatures lower than 800 degrees C. This result is interpreted by the intervention of two opposed diffusion phenomena which act against each other [fr

Corrosion cracking resistance of the VT3-1 titanium alloy with initial defects in the metal

International Nuclear Information System (INIS)

Konradi, G.G.; Mozhaev, A.V.; Zmievskij, V.I.; Sokolov, V.S.

1978-01-01

Investigated is the corrosion cracking resistance of thick sheet half-finished product of the VT3-1 alloy in 3% NaCl solution during 800 hrs. It is shown that crack development occurs during the first 24 hours with stress intensities above the threshold coefficient of stress intensities. Ratios of crack sizes permissible for using the alloy in the air and NaCl solution media are obtained

Mechanisms for formation and disruption of surface oxides: Final report

International Nuclear Information System (INIS)

Lumsden, J.B.

1987-08-01

Mill-annealed alloys 600, 690 and 800 were exposed to 10 and 50% caustic solutions containing 1% Na 2 CO 3 to initiate IGA. IGA reproducibly occurred in all three alloys in the 10% caustic solution at 350 0 C after a 240 h exposure and in the 50% caustic solution at 320 0 C after a 120 h exposure. Reproducible IGA did not occur in the 10% caustic solution at 320 0 C after a 120 h exposure. IGA was not observed in mill annealed plus thermally treated alloys 600 and 690 after exposure to any of the test conditions. IGA initiation was correlated with a dealloying mechanism in which the more active alloying metals, iron and chromium, selectively dissolve. Boric acid and calcium hydroxide additives were found to slow or prevent IGA by inhibiting dealloying. Titanates prevented IGA in alloys 600, 690 and 800, passivating the surface with a nickel titanate film

Microstructural studies on friction surfaced coatings of Ni-based alloys; Gefuegeuntersuchungen an reibgeschweissten Beschichtungen von Ni-Basislegierungen

Energy Technology Data Exchange (ETDEWEB)

Akram, Javed; Puli, Ramesh; Kalvala, Prasad Rao; Misra, Mano [Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgical Engineering

2015-07-01

Inconel 625, Inconel 600, Inconel 800H were friction surfaced on steel and Inconel substrates. The interface between steel and Ni-based alloys showed intermixing of two alloys while the interface between two Ni-based alloys showed no such intermixing. The XRD results confirmed that this intermixed zone consisted of mechanical mix two separate metals and no intermetallics were noticed. Friction surfaced Inconel coatings were metallurgically bonded to steel and Inconel substrates with out any physical defects such as voids or cracks. Friction surfaced coatings showed equiaxed fine grained microstructures (4-18 μm) compared with their consumable rod counterparts (12 - 85 μm). Scanning electron microscope electron backscattered diffraction results showed that the coatings consisted of mainly high angle grain boundaries indicative of dynamic recrystallization mechanism. The temperatures recorded using Infra Red camera showed that the temperature attained at the interface between rod and the substrate is about 1100 C. The grain size of the consumable rod was relatively fine near the coating/substrate interface and relatively coarser away from interface indicating the change in strain and temperature the rod experienced at or away from the interface.

47 CFR 65.800 - Rate base.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Rate base. 65.800 Section 65.800 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) INTERSTATE RATE OF RETURN PRESCRIPTION PROCEDURES AND METHODOLOGIES Rate Base § 65.800 Rate base. The rate base shall...

Mono-carboxylate conversion coatings for AZ31 Mg alloy protection

Energy Technology Data Exchange (ETDEWEB)

Frignani, A.; Grassi, V.; Zucchi, F.; Zanotto, F. [Corrosion Study Centre A. Dacco, University of Ferrara (Italy)

2011-11-15

Conversion coatings on a magnesium alloy were obtained by dipping AZ31 specimens in aqueous solutions of sodium salts of mono-carboxylic acids (stearic, palmitic, myristic, lauric, mono-carboxylate ion concentration from 1 to 5 mM, depending on the salt solubility) for 24 and 72 h at room temperature, or 24 h at 50 C. The influence exerted by the treatment time, bath temperature and alkyl chain length on the efficiency of these coatings was studied. The performances of the coatings were evaluated by potentiodynamic polarization curve recording after 1 h immersion in 0.05 M Na{sub 2}SO{sub 4} solution, while their temporal evolution was monitored by electrochemical impedance spectroscopy (EIS) spectra during 24 h. Further and long lasting tests were carried out also in 0.1 M NaCl solution. The efficiency of the coatings depended on the aliphatic chain length, and increased as the treatment time and the bath temperature were increased. The coating of lower homologue only hindered the cathodic process, while those of the higher homologues markedly inhibited the anodic process too. The best performances were displayed by 24 h-50 C stearic conversion coating, which maintained a very high efficiency for over 800 h immersion in 0.05 M sulphate solution. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Carbon-encapsulated nickel-cobalt alloys nanoparticles fabricated via new post-treatment strategy for hydrogen evolution in alkaline media

Science.gov (United States)

Guo, Hailing; Youliwasi, Nuerguli; Zhao, Lei; Chai, Yongming; Liu, Chenguang

2018-03-01

This paper addresses a new post-treatment strategy for the formation of carbon-encapsulated nickel-cobalt alloys nanoparticles, which is easily controlled the performance of target products via changing precursor composition, calcination conditions (e.g., temperature and atmosphere) and post-treatment condition. Glassy carbon electrode (GCE) modified by the as-obtained carbon-encapsulated mono- and bi-transition metal nanoparticles exhibit excellent electro-catalytic activity for hydrogen production in alkaline water electrolysis. Especially, Ni0.4Co0.6@N-Cs800-b catalyst prepared at 800 °C under an argon flow exhibited the best electrocatalytic performance towards HER. The high HER activity of the Ni0.4Co0.6@N-Cs800-b modified electrode is related to the appropriate nickel-cobalt metal ratio with high crystallinity, complete and homogeneous carbon layers outside of the nickel-cobalt with high conductivity and the synergistic effect of nickel-cobalt alloys that also accelerate electron transfer process.

Study of Cu-Al-Zn alloys hardness temperature dependence

International Nuclear Information System (INIS)

Kurmanova, D.T.; Skakov, M.K.; Melikhov, V.D.

2001-01-01

In the paper the results of studies for the Cu-Al-Zn ternary alloys hardness temperature dependence are presented. The method of 'hot hardness' has been used during study of the solid state phase transformations and under determination of the hot stability boundaries. Due to the samples brittleness a hardness temperature dependence definition is possible only from 350-400 deg. C. Sensitivity of the 'hot hardness' method is decreasing within high plasticity range, so the measurements have been carried out only up to 700-800 deg. C. It is shown, that the alloys hardness dependence character from temperature is close to exponential one within the certain structure modification existence domain

10 CFR 800.002 - Program management.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Program management. 800.002 Section 800.002 Energy DEPARTMENT OF ENERGY LOANS FOR BID OR PROPOSAL PREPARATION BY MINORITY BUSINESS ENTERPRISES SEEKING DOE CONTRACTS AND ASSISTANCE General § 800.002 Program management. Program management responsibility for...

Pt/Cu single-atom alloys as coke-resistant catalysts for efficient C-H activation

Science.gov (United States)

Marcinkowski, Matthew D.; Darby, Matthew T.; Liu, Jilei; Wimble, Joshua M.; Lucci, Felicia R.; Lee, Sungsik; Michaelides, Angelos; Flytzani-Stephanopoulos, Maria; Stamatakis, Michail; Sykes, E. Charles H.

2018-03-01

The recent availability of shale gas has led to a renewed interest in C-H bond activation as the first step towards the synthesis of fuels and fine chemicals. Heterogeneous catalysts based on Ni and Pt can perform this chemistry, but deactivate easily due to coke formation. Cu-based catalysts are not practical due to high C-H activation barriers, but their weaker binding to adsorbates offers resilience to coking. Using Pt/Cu single-atom alloys (SAAs), we examine C-H activation in a number of systems including methyl groups, methane and butane using a combination of simulations, surface science and catalysis studies. We find that Pt/Cu SAAs activate C-H bonds more efficiently than Cu, are stable for days under realistic operating conditions, and avoid the problem of coking typically encountered with Pt. Pt/Cu SAAs therefore offer a new approach to coke-resistant C-H activation chemistry, with the added economic benefit that the precious metal is diluted at the atomic limit.

Pt/Cu single-atom alloys as coke-resistant catalysts for efficient C–H activation

Energy Technology Data Exchange (ETDEWEB)

Marcinkowski, Matthew D.; Darby, Matthew T.; Liu, Jilei; Wimble, Joshua M.; Lucci, Felicia R.; Lee, Sungsik; Michaelides, Angelos; Flytzani-Stephanopoulos, Maria; Stamatakis, Michail; Sykes, E. Charles H.

2018-01-08

The recent availability of shale gas has led to a renewed interest in C-H bond activation as the first step towards synthesis of fuels and fine chemicals. Heterogeneous catalysts based on Ni and Pt can perform this chemistry, but deactivate easily due to coke formation. Cu- based catalysts are not practical for this chemistry due to high C-H activation barriers, but their weaker binding to adsorbates offers resilience to coking. Utilizing Pt/Cu single atom alloys (SAAs) we examine C-H activation in a number of systems including methyl groups, methane, and butane using a combination of simulations, surface science, and catalysis studies. We find that Pt/Cu SAAs activate C-H bonds more efficiently than Cu, are stable for days under realistic operating conditions, and avoid the problem of coking typically encountered with Pt. Pt/Cu SAAs therefore offer a new approach to coke resistant C-H activation chemistry with the added economic benefit that the precious metal is diluted at the atomic limit.

20 CFR 638.800 - Program management.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Program management. 638.800 Section 638.800... TITLE IV-B OF THE JOB TRAINING PARTNERSHIP ACT Administrative Provisions § 638.800 Program management. (a) The Job Corps Director shall establish and use internal program management procedures sufficient...

30 CFR 800.21 - Collateral bonds.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Collateral bonds. 800.21 Section 800.21 Mineral... FOR SURFACE COAL MINING AND RECLAMATION OPERATIONS UNDER REGULATORY PROGRAMS § 800.21 Collateral bonds. (a) Collateral bonds, except for letters of credit, cash accounts, and real property, shall be...

Incoloy 800 stands up to radiation and corrosion in high temperature gas cooled reactors

International Nuclear Information System (INIS)

Anon.

1975-01-01

Incoloy 800 has been selected for heat exchangers in helium cooled nuclear reactor prototypes for exposure to 350 to 800 0 C helium and high temperature high purity water and steam. 304H stainless steel used in heat exchangers in original design cracked in the superheater area, bellows and tubing after static pressure tests but before exposure to steam. Residual stress, chlorides, and oxygen were deduced to have caused the failures

Study of irradiated F82H steel and its model Fe-Cr alloy by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Huang, S.S.; Kitao, S.; Xu, Q.; Sato, K.; Yoshiie, T.

2013-01-01

In this work, Moessbauer spectroscopy which is a super-precision tool was conducted on F82H and its model Fe-Cr alloys before and after irradiation to take a further look on the interaction between carbides and point defects and Cr effect on microstructural evolution during irradiation in void incubation period. (J.P.N.)

Isothermal oxidation behavior of ternary Zr-Nb-Y alloys at high temperature

Energy Technology Data Exchange (ETDEWEB)

Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id [Research Center for Nuclear Materials and Radiometry, Jl. Tamansari 71, Bandung 40132 (Indonesia); Soepriyanto, Syoni; Basuki, Eddy Agus [Metallurgy Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Wiryolukito, Slameto [Materials Engineering, Institute Technology Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24

The effect of yttrium content on isothermal oxidation behavior of Zr-2,5%Nb-0,5%Y, Zr-2,5%Nb-1%Y Zr-2,5%Nb-1,5%Y alloy at high temperature has been studied. High temperature oxidation carried out at tube furnace in air at 600,700 and 800°C for 1 hour. Optical microscope is used for microstructure characterization of the alloy. Oxidized and un oxidized specimen was characterized by x-ray diffraction. In this study, kinetic oxidation of Zr-2,5%Nb with different Y content at high temperature has also been studied. Characterization by optical microscope showed that microstructure of Zr-Nb-Y alloys relatively unchanged and showed equiaxed microstructure. X-ray diffraction of the alloys depicted that the oxide scale formed during oxidation of zirconium alloys is monoclinic ZrO2 while unoxidised alloy showed two phase α and β phase. SEM-EDS examination shows that depletion of Zr composition took place under the oxide layer. Kinetic rate of oxidation of zirconium alloy showed that increasing oxidation temperature will increase oxidation rate but increasing yttrium content in the alloys will decrease oxidation rate.

Fabrication and Magnetic Properties of Co₂MnAl Heusler Alloys by Mechanical Alloying.

Science.gov (United States)

Lee, Chung-Hyo

2018-02-01

We have applied mechanical alloying (MA) to produce nanocrystalline Co2MnAl Heusler alloys using a mixture of elemental Co50Mn25Al25 powders. An optimal milling and heat treatment conditions to obtain a Co2MnAl Heusler phase with fine microstructure were investigated by X-ray diffraction, differential scanning calorimeter and vibrating sample magnetometer measurements. α-(Co, Mn, Al) FCC phases coupled with amorphous phase are obtained after 3 hours of MA without any evidence for the formation of Co2MnAl alloys. On the other hand, a Co2MnAl Heusler alloys can be obtained by the heat treatment of all MA samples up to 650 °C. X-ray diffraction result shows that the average grain size of Co2MnAl Heusler alloys prepared by MA for 5 h and heat treatment is in the range of 95 nm. The saturation magnetization of MA powders decreases with MA time due to the magnetic dilution by alloying with nonmagnetic Mn and Al elements. The magnetic hardening due to the reduction of the grain size with ball milling is also observed. However, the saturation magnetization of MA powders after heat treatment increases with MA time and reaches to a maximum value of 105 emu/g after 5 h of MA. It can be also seen that the coercivity of 5 h MA sample annealed at 650 °C is fairly low value of 25 Oe.

WC-3015 alloy (high-temperature alloy)

International Nuclear Information System (INIS)

Anon.

1974-01-01

WC-3015 Nb alloy containing 28 to 30 Hf, 1 to 2 Zr, 13 to 16 W, 0 to 4 Ta, 0 to 5 Ti, 0.07 to 0.33 C, less than or equal to 0.02 N, less than or equal to 0.03 O, less than or equal to 0.001 H was developed for use at high temperature in oxidizing environments. Its composition can be tailored to meet specific requirements. When WC-3015 is exposed to O at elevated temperature, Hf and Nb oxidized preferentially and HfO 2 dissolves in Nb 2 O 5 to form 6HfO-Nb 2 O 5 . This complex oxide has a tight cubic lattice which resists the diffusion of O into the substrate. During 24-h exposure to air at 2400 0 F, the alloy oxidizes to a depth of approximately 0.035 in. with a surface recession of 0 to 0.004 in. Oxidation resistance of WC-3015 welds and base material can be further enhanced greatly by applying silicide coatings. WC-3015 alloy can be machined by conventional and electrical-discharge methods. It can be hot worked readily by extrusion, forging or rolling. Cold working can be used at room or elevated temperature. It can be welded by the electron-beam or Tig processes. Physical constants, typical mechanical properties at 75 to 2400 0 F, and effects of composition and heat treatment on tensile and stress-rupture properties of the alloy are tabulated

31 CFR 800.201 - Business day.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Business day. 800.201 Section 800.201 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF INVESTMENT... FOREIGN PERSONS Definitions § 800.201 Business day. The term business day means Monday through Friday...

Anodic behavior of nickel alloys in media containing bicarbonate ions

International Nuclear Information System (INIS)

Zadorozne, N.S; Carranza, R. M.; Giordano, C.M.

2011-01-01

Alloy 22 has been designed to resist corrosion in oxidizing and reducing conditions. Thanks to these properties it is considered a possible candidate for the fabrication of containers of high-level radioactive waste. Since the containers provide services in natural environments characterized by multi-ionic solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is required in order to produce cracking. It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media potentials below trans-passivity. The aim of this work is to study the anodic behavior of Alloy 22 in different media containing bicarbonate and chloride ions in various concentrations and temperatures and compare the results with other alloys containing nickel, and relate them to the susceptibility to stress corrosion cracking in a future job. Polarization curves were made on alloy 22 (Ni-Cr-Mo), 600 (Ni- Cr-Fe), 800h (Ni-Fe- Cr) and 201 (Ni commercially pure) in the following environments: 1.148 mol/L NaHCO 3 , 1.148 mol/L NaHCO 3 + 1 mol/L NaCl, 1.148 mol/L NaHCO 3 + 0.1 mol/L NaCl. The tests were performed at the following temperatures: 90°C, 75°C, 60°C and 25°C. It was found that alloy 22 has a current peak in the anodic domain at potentials below trans-passivity between 200 and 300 m VECS, when the test temperature was 90°C. The potential, at which this peak occurred, increased with decreasing temperature. Also there was a variation of the peak with the composition of the solution. When bicarbonate ions were added to a solution containing chloride ions, the peak potential shifted to higher current densities, depending on the concentration of added chloride ions. It was found that diminishing the content of

High-temperature microstructural characteristics of a novel biomedical titanium alloy

International Nuclear Information System (INIS)

Chang, Ming-Chih; Luo, Chin-Wan; Huang, Mao-Suan; Ou, Keng-Liang; Lin, Li-Hsiang; Cheng, Hsin-Chung

2010-01-01

In this study, the high-temperature microstructural characteristics of the Ti-5Al-1Sn-1Fe-1Cr (Ti-5111) alloy were determined by optical microscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. During solution treatment between 800 and 1000 o C, the phase transformation sequence of the alloy was found to be (α + β) → (α + α' + β) → (α + α' + α'' + residual β) → (α' + β). The residual β phase subsequently transforms to the α'' phase during quenching. The driving force for this transformation is the cooling rate. The martensite starting point (Ms) and β transus temperature of the Ti-5111 alloy are nearly 860 and 960 o C, respectively. These values are lower than those of the Ti-6Al-4V alloy. Moreover, it is believed that the concentration of Al in α' martensite plays a crucial role in the formation of the twin-type martensite.

Weldability of AA 5052 H32 aluminium alloy by TIG welding and FSW process - A comparative study

Science.gov (United States)

Shanavas, S.; Raja Dhas, J. Edwin

2017-10-01

Aluminium 5xxx series alloys are the strongest non-heat treatable aluminium alloy. Its application found in automotive components and body structures due to its good formability, good strength, high corrosion resistance, and weight savings. In the present work, the influence of Tungsten Inert Gas (TIG) welding parameters on the quality of weld on AA 5052 H32 aluminium alloy plates were analyzed and the mechanical characterization of the joint so produced was compared with Friction stir (FS) welded joint. The selected input variable parameters are welding current and inert gas flow rate. Other parameters such as welding speed and arc voltage were kept constant throughout the study, based on the response from several trial runs conducted. The quality of the weld is measured in terms of ultimate tensile strength. A double side V-butt joints were fabricated by double pass on one side to ensure maximum strength of TIG welded joints. Macro and microstructural examination were conducted for both welding process.

Investigation of austenitic alloys for advanced heat recovery and hot-gas cleanup systems

Energy Technology Data Exchange (ETDEWEB)

Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

1997-12-01

Materials properties were collected for the design and construction of structural components for use in advanced heat recovery and hot gas cleanup systems. Alloys systems included 9Cr-1Mo-V steel, modified 316 stainless steel, modified type 310 stainless steel, modified 20Cr-25Ni-Nb stainless steel, and modified alloy 800. Experimental work was undertaken to expand the databases for potentially useful alloys. Types of testing included creep, stress-rupture, creep-crack growth, fatigue, and post-exposure short-time tensile tests. Because of the interest in relatively inexpensive alloys for service at 700 C and higher, research emphasis was placed on a modified type 310 stainless steel and a modified 20Cr-25Ni-Nb stainless steel. Both steels were found to have useful strength to 925 C with good weldability and ductility.

Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells

Directory of Open Access Journals (Sweden)

Yen-Tang Huang

2014-01-01

Full Text Available Hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H alloys were developed for application in Si-based thin-film solar cells. The effects of the germane concentration (RGeH4 and the hydrogen ratio (RH2 on the μc-Si1-xGex:H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a-Si1-xGex:H and μc-Si1-xGex:H were also compared. Similar to a-Si1-xGex:H, the preferential Ge incorporation was observed in μc-Si1-xGex:H. Moreover, a higher RH2 significantly promoted Ge incorporation for a-Si1-xGex:H, while the Ge content was not affected by RH2 in μc-Si1-xGex:H growth. Furthermore, to eliminate the crystallization effect, the 0.9 μm thick absorbers with a similar crystalline volume fraction were applied. With the increasing RGeH4, the accompanied increase in Ge content of μc-Si1-xGex:H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization of RH2 and RGeH4, the single-junction μc-Si1-xGex:H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared to μc-Si:H cell, the external quantum efficiency at 800 nm had a relative increase by 33.1%.

Effect of deformation and annealing on mechanical properties of nickel-rhenium alloys

International Nuclear Information System (INIS)

Mashkova, V.M.

1978-01-01

Studied have been the mechanical properties of nickel-rhenium alloys, depending on the extent of deformation and heat treatment leading to softening. The mechanical properties of the alloys have been estimated by the results of the tensile tests of wire samples. The softening of the alloy at different temperatures is judged about by the variation in hardness. The results of the study indicate that the most abrupt reduction in the hardness of the cold-hardened metal occurs at 900-1,000 deg C and the hold-time of 1 min. Increase in the hold-time at such temperature almost does not reduce the hardness. It is established that in order to soften nickel-rhenium alloys in the process of the cold-deformation at brief annealings in the air the hold-time should not exceed 5 min at 800-900 deg C

31 CFR 800.225 - United States.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false United States. 800.225 Section 800... TAKEOVERS BY FOREIGN PERSONS Definitions § 800.225 United States. The term United States or U.S. means the United States of America, the States of the United States, the District of Columbia, and any commonwealth...

Creep Rupture Properties for Base and Weld Metals of Alloy 617

International Nuclear Information System (INIS)

Kim, Woo-Gon; Kim, Min-Hwan; Park, Jae-Young; Ekaputra, I. M. W.

2015-01-01

The allowable deformation in the welds is also restricted to half the deformation permitted for the base metal, since the ductility of the welds at elevated temperatures is generally low. For a design use, the data of the tensile and creep properties for Alloy 617 WM should be sufficiently provided, and in particular, to develop a design code of Alloy 617 WM. However, the data for the WM are very rare and limited until now, although the data for the BM are available in the ASME draft code case, which was suspended at the end of the 1980s owing to a lack of support and interes. In this report, the creep data for Alloy 617 WM, which was fabricated by a gas tungsten arc welding (GTAW) procedure, were obtained by a series of creep tests at 800 .deg. C, and the creep properties of the WM were compared with those of the BM. The high-temperature creep properties for Alloy 617 WM, fabricated by a gas tungsten arc welding (GTAW) procedure, were investigated by a series of creep tests with different stress levels at 800 .deg. C, and the creep test data for the WM were compared with those of the BM. From the results, it was found that the WM had a slightly longer creep rupture life and lower creep rate than the BM, and a particularly lower rupture elongation. The lower creep rate in the WM was due to the lower rupture elongation than the BM

Investigation on wear resistance and corrosion resistance of electron beam cladding co-alloy coating on Inconel617

Science.gov (United States)

Liu, Hailang; Zhang, Guopei; Huang, Yiping; Qi, Zhengwei; Wang, Bo; Yu, Zhibiao; Wang, Dezhi

2018-04-01

To improve surface properties of Inconel 617 alloy (referred to as 617 alloy), co-alloy coating metallurgically bonded to substrate was prepared on the surface of 617 alloy by electron beam cladding. The microstructure, phase composition, microhardness, tribological properties and corrosion resistance of the coatings were investigated. The XRD results of the coatings reinforced by co-alloy (Co800) revealed the presence of γ-Co, CoCx and Cr23C6 phase as matrix and new metastable phases of Cr2Ni3 and Co3Mo2Si. These hypoeutectic structures contain primary dendrites and interdendritic eutectics. The metallurgical bonding forms well between the cladding layer and the matrix of 617 alloy. In most studied conditions, the co-alloy coating displays a better hardness, tribological performance, i.e., lower coefficient of frictions and wear rates, corrosion resistance in 1 mol L‑1 HCl solution, than the 617 alloy.

Microstructure and Mechanical Behavior of High-Entropy Alloys

Science.gov (United States)

Licavoli, Joseph J.; Gao, Michael C.; Sears, John S.; Jablonski, Paul D.; Hawk, Jeffrey A.

2015-10-01

High-entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion, usually of equal atomic percent, they have high configurational entropy, and thus, they hold the promise of interesting and useful properties such as enhanced strength and alloy stability. The present study investigates the mechanical behavior, fracture characteristics, and microstructure of two single-phase FCC HEAs CoCrFeNi and CoCrFeNiMn with some detailed attention given to melting, homogenization, and thermo-mechanical processing. Ingots approaching 8 kg in mass were made by vacuum induction melting to avoid the extrinsic factors inherent to small-scale laboratory button samples. A computationally based homogenization heat treatment was given to both alloys in order to eliminate any solidification segregation. The alloys were then fabricated in the usual way (forging, followed by hot rolling) with typical thermo-mechanical processing parameters employed. Transmission electron microscopy was subsequently used to assess the single-phase nature of the alloys prior to mechanical testing. Tensile specimens (ASTM E8) were prepared with tensile mechanical properties obtained from room temperature through 800 °C. Material from the gage section of selected tensile specimens was extracted to document room and elevated temperature deformation within the HEAs. Fracture surfaces were also examined to note fracture failure modes. The tensile behavior and selected tensile properties were compared with results in the literature for similar alloys.

14 CFR 1212.800 - Civil remedies.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Civil remedies. 1212.800 Section 1212.800... Comply With Requirements of This Part § 1212.800 Civil remedies. Failure to comply with the requirements of the Privacy Act and this part could subject NASA to civil suit under the provisions of 5 U.S.C...

Deformation Behavior of Al0.25CoCrFeNi High-Entropy Alloy after Recrystallization

Directory of Open Access Journals (Sweden)

Jinxiong Hou

2017-03-01

Full Text Available Cold rolling with subsequent annealing can be used to produce the recrystallized structure in high entropy alloys (HEAs. The Al0.25CoCrFeNi HEAs rolled to different final thickness (230, 400, 540, 800, 1000, 1500 μm are prepared to investigate their microstructure evolutions and mechanical behaviors after annealing. Only the single face-centered cubic phase was obtained after cold rolling and recrystallization annealing at 1100 °C for 10 h. The average recrystallized grain size in this alloy after annealing ranges from 92 μm to 136 μm. The annealed thin sheets show obviously size effects on the flow stress and formability. The yield strength and tensile strength decrease as t/d (thickness/average grain diameter ratio decreases until the t/d approaches 2.23. In addition, the stretchability (formability decreases with the decrease of the t/d ratio especially when the t/d ratio is lower than about 6. According to the present results, yield strength can be expressed as a function of the t/d ratio.

Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings -- Phase 2 field testing

Energy Technology Data Exchange (ETDEWEB)

Blough, J.L.; Seitz, W.W.; Girshik, A. [Foster Wheeler Development Corp., Livingston, NJ (United States)

1998-06-01

In Phase 1 of this project, laboratory experiments were performed on a variety of developmental and commercial tubing alloys and claddings by exposing them to fireside corrosion tests which simulated a superheater or reheater in a coal-fired boiler. Phase 2 (in situ testing) has exposed samples of 347, RA85H, HR3C, RA253MA, Fe{sub 3}Al + 5Cr, Ta-modified 310, NF 709, 690 clad, 671 clad, and 800HT for up to approximately 16,000 hours to the actual operating conditions of a 250-MW, coal-fired boiler. The samples were installed on air-cooled, retractable corrosion probes, installed in the reheater cavity, and controlled to the operating metal temperatures of an existing and advanced-cycle, coal-fired boiler. Samples of each alloy were exposed for 4,483, 11,348, and 15,883 hours of operation. The present results are for the metallurgical examination of the corrosion probe samples after the full 15,883 hours of exposure. A previous topical report has been issued for the 4,483 hours of exposure.

Polymer-Derived Ceramics as Innovative Oxidation Barrier Coatings for Mo-Si-B Alloys

Science.gov (United States)

Hasemann, Georg; Baumann, Torben; Dieck, Sebastian; Rannabauer, Stefan; Krüger, Manja

2015-04-01

A preceramic polymer precursor, perhydropolysilazane, is used to investigate its function as a new type of oxidation barrier coating on Mo-Si-B alloys. After dip-coating and pyrolysis at 1073 K (800 °C), dense and well-adhering SiON ceramic coatings could be achieved, which were investigated by SEM and cyclic oxidation tests at 1073 K and 1373 K (800 °C and 1100 °C). The coating is promising in reducing the mass loss during the initial stage of oxidation exposure at 1373 K (1100 °C) significantly.

Hot deformation behavior of TC18 titanium alloy

Directory of Open Access Journals (Sweden)

Jia Bao-Hua

2013-01-01

Full Text Available Isothermal compression tests of TC18 titanium alloy at the deformation temperatures ranging from 25°C to 800°C and strain rate ranging from 10-4 to 10-2 s-1 were conducted by using a WDW-300 electronic universal testing machine. The hot deformation behavior of TC18 was characterized based on an analysis of the true stress-true strain curves of TC18 titanium alloy. The curves show that the flow stress increases with increasing the strain rate and decreases with increasing the temperature, and the strain rate play an important role in the flow stress when increasing the temperatures. By taking the effect of strain into account, an improved constitutive relationship was proposed based on the Arrhenius equation. By comparison with the experimental results, the model prediction agreed well with the experimental data, which demonstrated the established constitutive relationship was reliable and can be used to predict the hot deformation behavior of TC18 titanium alloy.

Microstructure and magnetic behavior of Cu–Co–Si ternary alloy synthesized by mechanical alloying and isothermal annealing

Energy Technology Data Exchange (ETDEWEB)

Chabri, Sumit, E-mail: sumitchabri2006@gmail.com [Department of Metallurgy & Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Bera, S. [Department of Metallurgical & Materials Engineering, National Institute of Technology, Durgapur 713209 (India); Mondal, B.N. [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Basumallick, A.; Chattopadhyay, P.P. [Department of Metallurgy & Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India)

2017-03-15

Microstructure and magnetic behavior of nanocrystalline 50Cu–40Co–10Si (at%) alloy prepared by mechanical alloying and subsequent isothermal annealing in the temperature range of 450–650 °C have been studied. Phase evolution during mechanical alloying and isothermal annealing is characterized by X-ray diffraction (XRD), differential thermal analyzer (DTA), high resolution transmission electron microscopy (HRTEM) and magnetic measurement. Addition of Si has been found to facilitate the metastable alloying of Co in Cu resulting into the formation of single phase solid solution having average grain size of 9 nm after ball milling for 50 h duration. Annealing of the ball milled alloy improves the magnetic properties significantly and best combination of magnetic properties has been obtained after annealing at 550 °C for 1 h duration.

Nanostructured Al–Zn–Mg–Cu–Zr alloy prepared by mechanical alloying followed by hot pressing

International Nuclear Information System (INIS)

Azimi, Amin; Shokuhfar, Ali; Zolriasatein, Ashkan

2014-01-01

Nanostructured Al–7.8 wt% Zn–2.6 wt% Mg–2 wt% Cu–0.1 wt% Zr alloy was mechanically alloyed (MA) from elemental powders and consolidated by hot press technique. The effect of the milling time and hot pressing process on microstructure was investigated by means of X-ray diffraction measurements (XRD) and analytical and scanning electron microscopy (SEM). Furthermore mechanical properties of samples with different MA time as well as pure aluminum were investigated by microhardness and compression tests. The results show that an Al–Zn–Mg–Cu–Zr homogenous supersaturated solid solution with a crystallite size of 27 nm was obtained after 40 h of milling time. Microstructure refinement and morphological changes of powders from flake to spherical shape were observed by increasing milling time. Phase and microstructural characterization of high density bulk nanostructured samples revealed that increasing milling time up to 40 h leads to formation of MgZn 2 precipitation in the alloy matrix. With increasing milling time, density of the samples and crystalline size decrease. Significant enhancement of hardness and compressive strength is observed in the aluminum alloy by increasing milling time up to 40 h which is much higher than pure aluminum. Crystallite size refinement in pure aluminum samples from micro- to nanoscales resulted in 107% and 100% improvement in compressive strength and hardness, respectively. Furthermore the compressive strength and hardness of Al–Zn–Mg–Cu–Zr alloy nanostructured samples increased to 179% and 172%, respectively, compared to nanostructured pure Al, which was produced as reference specimen. 40 h of MA was the optimum case for preparing such an Al alloy and more milling up to 50 h led to deterioration of mechanical properties

Manufacturing and testing of self-passivating tungsten alloys of different composition

Directory of Open Access Journals (Sweden)

A. Calvo

2016-12-01

Bulk W-15Cr, W-10Cr-2Ti and W-12Cr-0.5Y alloys were manufactured by mechanical alloying followed by can encapsulation and HIP. This route resulted in fully dense materials with nano-structured grains. The ability of Ti and especially of Y to inhibit grain growth was observed in the W-10Cr-2Ti and W-12Cr-0.5Y alloys. Besides, Y formed Y-rich oxide nano-precipitates at the grain boundaries, and is thus expected to improve the mechanical behaviour of the Y-containing alloy. Isothermal oxidation tests at 800 ºC (1073K and oxidation tests under accident-like conditions revealed that the W-12Cr-0.5Y alloy exhibits the best oxidation behaviour of all alloys, especially in the accident-like scenario. Preliminary HHF tests performed at GLADIS indicated that the W-10Cr-2Ti alloy is able to withstand power densities of 2 MW/m2 without significant damage of the bulk structure. Thermo-shock tests at JUDITH-1 to simulate mitigated disruptions resulted in chipping of part of the surface of the as-HIPed W-10Cr-2Ti alloy. An additional thermal treatment at 1600 °C (1873K improves the thermo-shock resistance of the W-10Cr-2Ti alloy since only crack formation is observed.

Influence of the alloying elements vanadium, chromium and carbon on the electrochemical behavior of uranium in media with a pH 13 or a pH acid

International Nuclear Information System (INIS)

Pommier, Gerard; Jouve, Gerard; Lacombe, Paul.

1976-06-01

The electrochemical properties of uranium alloys with low vanadium and chromium contents were studied in aqueous medium for different pH values of the solution (pH between 0 and 5 in H 2 SO 4 medium and pH=13 in NaOH medium). In acid medium, the study of the behavior of the two types of alloys carried out by the potentiokinetic method is described. The specific role of chromium concerning the anodic process is demonstrated and the influence of vanadium in specimens of same nominal vanadium contents but different carbon contents is revealed by the modification of the reduction overvoltage of water. In basic medium, the electrochemical study was supported by an optical method of determining the relative growth kinetics of the films in situ and continuously. At lower values of potential, the growth of an oxide film of UO 2 with linear growth kinetics is demonstrated; at higher values of potential a system of two layers is observed and its evolution is followed kinematically. The film initially formed is constituted of an oxide UO 3 2H 2 O, and its growth is linear, then a film of UO 2 develops underneath. A structural evolution of the superficial film is then observed, an evolution which leads to its cracking after breakdown. These phenomena were followed by electron microscopy using a technic of two stage replicas [fr

Comparative study on the high-temperature tensile and creep properties of Alloy 617 base and weld metals

International Nuclear Information System (INIS)

Kim, Woo Gon; Hong, Sung Deok; Kim, Yong Wan; Kim, Seon Jin; Park, Jae Young; Ekaputra, I. M. W.

2013-01-01

This paper presents a comparative investigation on the high-temperature tensile and creep properties of Alloy 617 base metal (BM) and weld metal (WM) fabricated by a gas tungsten arc weld process. The WM had higher yield strength and lower ultimate tensile strength than the BM does; however, its elongation was significantly lower than that of the BM. The creep curve of the BM and WM was somewhat different from that of typical heat-resistance steel, and did not show a textbook creep. The WM exhibited a longer creep rupture life, lower creep rate, and lower rupture ductility than the BM. However, as the creep rupture time reached approximately 36,800 h, the creep life of the WM was expected to be almost similar to that of the BM; and after 36,800 h, its creep life was expected to be worse than the BM. Loner creep tests is needed to investigate the long-term creep life of the WM. The creep failure mode of the BM and WM was obviously an intergranular cracking of the cavity formation and growth mechanisms, although it was more evident in the WM. The BM had a more ductile fracture surface than the WM

Copper alloys with improved properties: standard ingot metallurgy vs. powder metallurgy

Directory of Open Access Journals (Sweden)

Milan T. Jovanović

2014-09-01

Full Text Available Three copper-based alloys: two composites reinforced with Al2O3 particles and processed through powder metallurgy (P/M route, i.e. by internal oxidation (Cu-2.5Al composite and by mechanical alloying (Cu-4.7Al2O3 and Cu-0.4Cr-0.08Zr alloy produced by ingot metallurgy (vacuum melting and casting were the object of this investigation. Light microscope and scanning electron microscope (SEM equipped with electron X-ray spectrometer (EDS were used for microstructural characterization. Microhardness and electrical conductivity were also measured. Compared to composite materials, Cu-0.4Cr-0.08Zr alloy possesses highest electrical conductivity in the range from 20 to 800 ℃, whereas the lowest conductivity shows composite Cu-2.5Al processed by internal oxidation. In spite to somewhat lower electrical conductivity (probably due to inadequate density, Cu-2.5Al composite exhibits thermal stability enabling its application at much higher temperatures than materials processed by mechanical alloying or by vacuum melting and casting.

Effect of fluoride content on ion release from cast and selective laser melting-processed Co-Cr-Mo alloys.

Science.gov (United States)

Yang, Xu; Xiang, Nan; Wei, Bin

2014-11-01

Selective laser melting (SLM) alloy is gaining popularity in prosthetic dentistry. However, its biocompatibility has been of some concern because of long-term exposure to fluoride in the oral environment. The purpose of this study was to examine the effect of fluoride concentration on ion release from Co-Cr-Mo alloy specimens fabricated using either SLM or lost-wax casting when immersed in an artificial saliva solution containing fluoride. Specimens were prepared with either a SLM system for the SLM alloy or conventional lost-wax techniques for the cast alloy. The specimen surfaces were wet ground with silicon carbide paper (400, 800, and 1200 grit) and immersed in modified artificial saliva solutions, the pH of which had been adjusted to 5.0 with lactic acid and which contained NaF at concentrations of 0.00%, 0.05%, 0.1%, or 0.2%. The metal ion content of the solution was determined with an inductively coupled plasma mass spectrometer. The results were submitted to 2-way ANOVA and regression analysis (α=.05). Fluoride concentration significantly influenced the elemental ion release from both the SLM and cast alloys. The quantity of ions released increased significantly with increasing fluoride concentration. The ion release from the cast specimens was significantly greater than that from the SLM specimens. The performance of the SLM alloy in immersion tests demonstrates that this new technique is a superior choice because of its good biocompatibility. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Formation and stability of Fe-rich precipitates in dilute Zr(Fe) single-crystal alloys

International Nuclear Information System (INIS)

Zou, H.; Hood, G.M.; Roy, J.A.; Schultz, R.J.

1993-02-01

The formation and stability of Fe-rich precipitates in two α-Zr(Fe) single-crystal alloys with nominal compositions (I, 50 ppma Fe, and II, 650 ppma Fe) have been investigated (the maximum solid solubility of Fe in α-Zr is 180 ppma - 800 C). Optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to examine the characteristics of Fe-rich precipitates. SEM and TEM micrographs show that in as-grown alloy II, Zr 2 Fe precipitates are located at 'stringers'. Precipitates were not observed in as-grown alloy I. During annealing, below the solvus, Fe diffuses to the surfaces to form Zr 3 Fe precipitates in both alloys. The precipitates on the surfaces of alloy I tend to be star-like (0001) or pyramidal (1010), and their distribution is heterogeneous. Dissolution of Zr 3 Fe surface precipitates of alloy I (annealing above the solvus) leaves precipitate-like features on the surfaces. Zr 2 Fe precipitates in as-grown alloy II can be dissolved only by β-phase annealing. (Author) 8 figs., 18 refs

17 CFR 230.800 - Definitions for §§ 230.800, 230.801 and 230.802.

Science.gov (United States)

2010-04-01

... Rights Offerings, Exchange Offers and Business Combinations § 230.800 Definitions for §§ 230.800, 230.801... combination. Business combination means a statutory amalgamation, merger, arrangement or other reorganization... of the exchange offer or business combination. (f) Home jurisdiction. Home jurisdiction means both...

24 CFR 241.800 - Definitions.

Science.gov (United States)

2010-04-01

... SUPPLEMENTARY FINANCING FOR INSURED PROJECT MORTGAGES Contract Rights and Obligations-Multifamily Projects Without a HUD-Insured or HUD-Held Mortgage § 241.800 Definitions. All of the definitions contained in... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Definitions. 241.800 Section 241...

Elevated temperature creep behavior of Inconel alloy 625

International Nuclear Information System (INIS)

Purohit, A.; Burke, W.F.

1984-07-01

Inconel 625 in the solution-annealed condition has been selected as the clad material for the fuel and control rod housing assemblies of the Upgraded Transient Reactor Test Facility (TREAT Upgrade or TU). The clad is expected to be subjected to temperatures up to about 1100 0 C. Creep behavior for the temperature range of 800 0 C to 1100 0 C of Inconel alloy 625, in four distinct heat treated conditions, was experimentally evaluated

Corrosion of alloys of the niobium--titanium--aluminium system

International Nuclear Information System (INIS)

Andreeva, V.V.; Alekseeva, E.L.; Dontsov, S.N.; Moiseeva, I.S.

The mechanical properties and corrosion resistance of niobium--titanium--aluminum alloys in 20 percent HCl and 40--75 percent H 2 SO 4 at 40 and 100 0 C are considered. Current density vs potential and corrosion rate vs potential potentiostatic curves plotted in 75 percent H 2 SO 4 at 140 0 C for the alloys with different titanium contents at a constant content of aluminum and also for alloys with a constant titanium content at different contents of aluminum are given. It was shown that the corrosion resistance of the alloys in 75 percent H 2 SO 4 at 140 0 C is an exponential function of the atomic content of the alloying components (Ti, Al) in them; aluminum vitiates the corrosion resistance very strongly

Effects of annealing on tensile property and corrosion behavior of Ti-Al-Zr alloy

International Nuclear Information System (INIS)

Kim, Tae-Kyu; Choi, Byung-Seon; Jeong, Yong-Hwan; Lee, Doo-Jeong; Chang, Moon-Hee

2002-01-01

The effects of annealing on the tensile property and corrosion behavior of Ti-Al-Zr alloy were evaluated. The annealing in the temperature range from 500 to 800 deg. C for 1 h induced the growth of the grain and the precipitate sizes. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. However, the results of corrosion test in an ammonia aqueous solution of pH 9.98 at 360 deg. C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 220 days also increased with the annealing temperature. It could be attributed to the growth of Fe-rich precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties

The Thermodynamic Characterization of ZrCo–H, HfCo−H, HfNi−H and Zr{sub 1–x}HfxNi(Co) Alloy–H Systems

Energy Technology Data Exchange (ETDEWEB)

Flanagan, Ted B., E-mail: ted.flanagan@uvm.edu; Noh, Hak; Luo, Suifang

2016-08-25

ZrCo and HfCo intermetallic compounds have the same cubic (CsCl-type) structure and their ternary (Zr{sub 1−x}Hf{sub x})Co alloys are also cubic. ZrNi and HfNi intermetallic compounds have the orthorhombic structure (CrB-type) and the ternary (Zr{sub 1−x}Hf{sub x})Ni alloys also have this structure. Thermodynamic data for hydride formation and decomposition in ZrCo, HfCo and HfNi intermetallic compounds have been determined from reaction calorimetry and from pressure-composition isotherms. Thermodynamic data have been determined for the three ternary alloys: (Zr{sub 0.75}Hf{sub 0.25})Co, (Zr{sub 0.50}Hf{sub 0.50})Co, and (Zr{sub 0.25}Hf{sub 0.75})Co and the four ternary alloys: (Zr{sub 0.875}Hf{sub 0.125})Ni, (Zr{sub 0.75}Hf{sub 0.25})Ni, (Zr{sub 0.50}Hf{sub 0.50})Ni, and (Zr{sub 0.25}Hf{sub 0.75})Ni. This offers the opportunity to learn how the thermodynamic properties of the ternary alloy-H systems change with the stoichiometry of alloys with the same structure. - Highlights: • Calorimetric enthalpies determined for H absorption by ZrCo, HfCo, HfNi are determined. • Ternary alloys, e.g., Zr{sub 1−x}Hf{sub x}Ni, prepared and characterized by x-ray diffraction. • Isotherms for the ternary alloys give thermodynamic parameters for H solution.

IMac G4/800 (Flat Panel)

CERN Multimedia

2002-01-01

Apple introduced the iMac G4/800 on January 7, 2002. The total cost was about $2000 (base price of $1799 plus RAM upgrade). The iMac G4/800 has an 800 MHz G4 processor. The G4/800 has the following ports: three USB 1.1 ports, two Fire Wire 400-Mbps ports, one RJ-45, 10/100BASE-T Ethernet port, one RJ-11 56K V.90 modem port, one Mini-VGA output port, one speaker jack, and one headphone jack. There is a built in microphone set on the front of the monitor in the bottom left corner. There is a single internal SuperDrive capable of reading and writing CDs and DVDs. The disk drive is on the front of the computer. It opens by pushing the disk drive button on the iMac's keyboard. The monitor size is 15 inches. The G4/800 has a NVIDIA GeForce2 MX graphics processor with AGP 2X support that provides 32 MB of dedicated Double Data Rate (DDR) video memory. Native resolution is 1024 x 768, but the built in monitor is also capable of 640 x 480 and 800 x 600. RAM can be changed by removing a panel on the bottom of the chas...

31 CFR 800.204 - Control.

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2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Control. 800.204 Section 800.204 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF INVESTMENT... preferences of the particular class of stock held by minority investors, as provided in the relevant corporate...

31 CFR 800.211 - Entity.

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2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Entity. 800.211 Section 800.211 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF INVESTMENT... separate legal entity) operated by any one of the foregoing as a business undertaking in a particular...

Microstructures of friction surfaced coatings. A TEM study; Gefuege durch Reibauftragschweissen aufgetragener Beschichtungen. Eine TEM-Untersuchung

Energy Technology Data Exchange (ETDEWEB)

Akram, Javed; Kalvala, Prasad Rao; Misra, Mano [Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgical Engineering; Dilip, J. John Samuel [Louisville Univ., KY (United States). Dept. of Industrial Engineering; Pal, Deepankar; Stucker, Brent [Louisville Univ., KY (United States). Dept. of Industrial Engineering; 3D Sim, Park City, UT (United States)

2016-05-15

The microstructures of dissimilar metal welds between 9Cr-1Mo (Modified) (P91) and austenitic stainless steel (AISI 304) with Ni-based alloy interlayers (Inconel 625, Inconel 600 and Inconel 800H) are reported. These interlayers were deposited by the friction surfacing method one over the other on P91 alloy, which was finally friction welded to AISI 304. In this paper, the results of microstructural evolution in the friction surfaced coated interlayers (Inconel 625, 600, 800H) are reported. For comparative purposes, the microstructures of consumable rods (Inconel 625, 600, 800H) and dissimilar metal base metals (P91 and AISI 304) were also reported. Friction surfaced coatings exhibited dynamic recrystallization. In friction surfaced coatings, the carbide particles were found to be finer and distributed uniformly throughout the matrix, compared to their rod counterparts.

Microstructures of friction surfaced coatings. A TEM study

International Nuclear Information System (INIS)

Akram, Javed; Kalvala, Prasad Rao; Misra, Mano

2016-01-01

The microstructures of dissimilar metal welds between 9Cr-1Mo (Modified) (P91) and austenitic stainless steel (AISI 304) with Ni-based alloy interlayers (Inconel 625, Inconel 600 and Inconel 800H) are reported. These interlayers were deposited by the friction surfacing method one over the other on P91 alloy, which was finally friction welded to AISI 304. In this paper, the results of microstructural evolution in the friction surfaced coated interlayers (Inconel 625, 600, 800H) are reported. For comparative purposes, the microstructures of consumable rods (Inconel 625, 600, 800H) and dissimilar metal base metals (P91 and AISI 304) were also reported. Friction surfaced coatings exhibited dynamic recrystallization. In friction surfaced coatings, the carbide particles were found to be finer and distributed uniformly throughout the matrix, compared to their rod counterparts.

The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

Directory of Open Access Journals (Sweden)

H. Suwarno

2009-07-01

Full Text Available The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.

Microstructure/Oxidation/Microhardness Correlations in Gamma-Based and Tau-Based Al-Ti-Cr Alloys

Science.gov (United States)

Brady, Michael P.; Smialek, J. L.; Humphrey, D. L.

1994-01-01

The relationships between alloy microstructure and air oxidation kinetics and alloy microstructure and microhardness in the Al-Ti-Cr system for exposures at 800 C and 1000 C were investigated. The relevant phases were identified as tau (Ll2), gamma (LIO), r-Al2Ti, TiCrAl (laves), and Cr2AI. Protective alumina formation was associated with tau, Al-rich TiCrAl, and gamma/TiCrAl mixtures. Brittleness was associated with the TiCrAl phase and tau decomposition to A12Ti + Cr2AI. It was concluded that two-phase gamma + TiCrAl alloys offer the greatest potential for oxidation resistance and room temperature ductility in the Al-Ti-Cr system.

Fabrication of nanocrystalline alloys Cu–Cr–Mo super satured solid solution by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y Centro Regional de Investigación y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapó (Chile); Castro, F.; Martínez, V.; Cuevas, F. de las [Centro de Estudios e Investigaciones Técnicas de Gipuzkoa, Paseo de Manuel Lardizábal, N° 15, 20018 San Sebastián (Spain); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Muthiah, T. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

2014-08-01

This work discusses the extension of solid solubility of Cr and Mo in Cu processed by mechanical alloying. Three alloys processed, Cu–5Cr–5Mo, Cu–10Cr–10Mo and Cu–15Cr–15Mo (weight%) using a SPEX mill. Gibbs free energy of mixing values 10, 15 and 20 kJ mol{sup −1} were calculated for these three alloys respectively by using the Miedema's model. The crystallite size decreases and dislocation density increases when the milling time increases, so Gibbs free energy storage in powders increases by the presence of crystalline defects. The energy produced by crystallite boundaries and strain dislocations were estimated and compared with Gibbs free energy of mixing values. The energy storage values by the presence of crystalline defects were higher than Gibbs free energy of mixing at 120 h for Cu–5Cr–5Mo, 130 h for Cu–10Cr–10Mo and 150 h for Cu–15Cr–15Mo. During milling, crystalline defects are produced that increases the Gibbs free energy storage and thus the Gibbs free energy curves are moved upwards and hence the solubility limit changes. Therefore, the three alloys form solid solutions after these milling time, which are supported with the XRD results. - Highlights: • Extension of solid solution Cr and Mo in Cu achieved by mechanical alloying. • X-ray characterization of Cu–Cr–Mo system processed by mechanical alloying. • Thermodynamics analysis of formation of solid solution of the Cu–Cr–Mo system.

Superplastic Deformation of TC6 Alloy

Directory of Open Access Journals (Sweden)

DING Ling

2016-12-01

Full Text Available The superplastic tensile tests of TC6 alloy were conducted in the temperature range of 800-900℃ by using the maximum m value superplasticity deformation (Max m SPD method and the constant strain rate deformation method at the strain rate range of 0.0001-0.1 s-1. The stress-strain curve of the tensile tests was obtained and the microstructure near the fracture were analyzed by metallographic microscope. The result shows that the superplasticity of TC6 alloy is excellent, and the elongation increases first and then decreases with the increase of strain rate or temperature. When the temperature is 850℃ and strain rate is 0.001 s-1 at constant stain rate tensile tests, the elongation reaches up to 993%. However, the elongation using Max m SPD method at 850℃ is 1353%. It is shown that the material can achieve better superplasticity by using Max m SPD tensile compared to constant stain rate tensile under the same temperature. The superplastic deformation of TC6 alloy can enhance the dynamic recrystallization behavior significantly, the dynamic recrystallization behavior is promoted when strain rate and temperature are increased.

Reduction in the formation temperature of Poly-SiGe alloy thin film in Si/Ge system

Science.gov (United States)

Tah, Twisha; Singh, Ch. Kishan; Madapu, K. K.; Sarguna, R. M.; Magudapathy, P.; Ilango, S.

2018-04-01

The role of deposition temperature in the formation of poly-SiGe alloy thin film in Si/Ge system is reported. For the set ofsamples deposited without any intentional heating, initiation of alloying starts upon post annealingat ˜ 500 °C leading to the formation of a-SiGe. Subsequently, poly-SiGe alloy phase could formonly at temperature ≥ 800 °C. Whereas, for the set of samples deposited at 500 °C, in-situ formation of poly-SiGe alloy thin film could be observed. The energetics of the incoming evaporated atoms and theirsubsequent diffusionsin the presence of the supplied thermal energy is discussed to understand possible reasons for lowering of formation temperature/energyof the poly-SiGe phase.

7 CFR 800.138 - Conflict of interest.

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2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Conflict of interest. 800.138 Section 800.138 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD... Inspection Services § 800.138 Conflict of interest. Official personnel cannot perform or participate in...

7 CFR 800.128 - Conflicts of interest.

Science.gov (United States)

2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Conflicts of interest. 800.128 Section 800.128 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD... Reinspection Services and Review of Weighing Services § 800.128 Conflicts of interest. Official personnel...

Corrosion resistance of tantalum base alloys

International Nuclear Information System (INIS)

Gypen, L.A.; Brabers, M.; Deruyttre, A.

1984-01-01

The corrosion behaviour of substitutional Ta-Mo, Ta-W, Ta-Nb, Ta-Hf, Ta-Zr, Ta-Re, Ta-Ni, Ta-V, Ta-W-Mo, Ta-W-Nb, Ta-W-Hf and Ta-W-Re alloys has been investigated in various corrosive media, i.e. (1) concentrated sulfuric acid at 250 0 C and 200 0 C, (2) boiling hydrochloric acid of azeotropic composition, (3) concentrated hydrochloric acid at 150 0 C under pressure, (4) HF-Containing solutions and (5) 0.5% H 2 SO 4 at room temperature (anodisation). In highly corrosive media such as concentrated H 2 SO 4 at 250 0 C and concentrated HCl at 150 0 C tantalum is hydrogen embrittled, probably by stress induced precipitation of β-hydride. Both corrosion rate and hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C are strongly influenced by alloying elements. Small alloying additions of either Mo or Re decrease the corrosion rate and the hydrogen embrittlement, while Hf has the opposite effect. Hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C is completely eliminated by alloying Ta with 1 to 3 at % Mo (0.5 to 1.5 wt % Mo). These results can be explained in terms of oxygen deficiency of the Ta 2 O 5 film and the electronic structure of these alloys. (orig.) [de

On the significance of a subsequent ageing after cold working of Incoloy 800 at operational temperatures

International Nuclear Information System (INIS)

Ullrich, G.; Krompholz, K.

1993-01-01

The influence of cold working and subsequent ageing at operational temperatures on the long-term and short-term mechanical properties of components made from the iron-nickel-chromium base alloy Incoloy 800 are discussed. Long-term properties are time-to-rupture strengths, which are included in the design code, over a lifetime of 300,000 hours. For LWR operating temperatures of 350 o C, this is of minor importance. An operating temperature of 550 o C is possible for Incoloy 800 with up to 25% cold working and a subsequent solution annealing at 950 o C, without loss of time-to-rupture strength compared with the 'as received' state. The short-term mechanical properties are strongly influenced by cold working, in the form of increasing yield strength and rupture strength, and decreasing ductility and consequently loss in impact energies. A subsequent ageing at 550 o C leads to a decrease of the yield strength and rupture strength, and an increase of ductility as well as the impact energies. The environmental influence are discussed. (author) 3 figs., 1 tab., 8 refs

30 CFR 800.30 - Replacement of bonds.

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2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Replacement of bonds. 800.30 Section 800.30... REQUIREMENTS FOR SURFACE COAL MINING AND RECLAMATION OPERATIONS UNDER REGULATORY PROGRAMS § 800.30 Replacement... replacement performance bonds. Replacement of a performance bond pursuant to this section shall not constitute...

33 CFR 117.800 - Mill Neck Creek.

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2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Mill Neck Creek. 117.800 Section 117.800 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New York § 117.800 Mill Neck Creek. The draw of the...

Electrochemical and surface characterisation of oxide films on nano-grain nickel films electrodeposited on INCOLOY-800

International Nuclear Information System (INIS)

Navin Vinayak, S.; Sunitha, Y.; Rangarajan, S.; Narasimhan, S.V.

2008-01-01

Nano materials have different properties from the corresponding bulk materials because of fine grain size, large fraction of surface atoms, high surface energy and high grain boundary volume fraction. For similar reasons, the nano-alloy coatings show superior high-temperature corrosion resistance and are generally more resistant to stress corrosion cracking. Hence, it is of interest to know the materials performance, if the structural materials used in nuclear reactors are made of nano-grains. In Indian PHWRs, Incoloy-800 is being used as the steam generator tubing material. It's corrosion resistance property is very important as it forms not only the pressure boundary between the radioactive primary water and non-active secondary water but also from the view point of loss of heavy water, in case of any corrosion damage. In this paper, the corrosion resistance of the oxide films formed on nano-grain nickel film electrodeposited on Incoloy-800 (a) in the presence of saccharine (WS) and (b) in the absence of saccharine (WOS) were compared with that formed on Commercial Ni foil, using electrochemical dc polarization and ac impedance techniques. The surface morphology, elemental analysis and grain size were studied with SEM, EDX and XRD techniques respectively. The nano-grain nickel films were prepared on Incoloy-800 by electrodeposition using Watt's Bath with saccharine sodium as a surfactant. The oxide films were developed by exposing them to LiOH solution (pH-10.0) at 245 deg C for 3 days (A-group) and 7 days (B-group). XRD results showed that the grain size of Ni formed in the absence of saccharine (WOS) was ∼ 60 nm and did not change after being autoclaved. But, for Ni formed in the presence of saccharine (WS), the grain size was ∼ 16 nm which increased to 40-50 nm after being autoclaved. With both A and B-group specimens, the PDAP curves showed an active-passive transition, a passive region and a transpassive region in 2N H 2 SO 4 . However, the critical

An electrochemical investigation of TMJ implant metal alloys in an artificial joint fluid environment: the influence of pH variation.

Science.gov (United States)

Royhman, Dmitry; Radhakrishnan, Rashmi; Yuan, Judy Chia-Chun; Mathew, Mathew T; Mercuri, Louis G; Sukotjo, Cortino

2014-10-01

To investigate the corrosion behaviour of commonly used TMJ implants alloys (CoCrMo and Ti6Al4V) under simulated physiological conditions. Corrosion behaviour was evaluated using standard electrochemical corrosion techniques and galvanic corrosion techniques as per ASTM standards. Standard electrochemical tests (E(corr), I(corr), R(p) and C(f)) were conducted in bovine calf serum (BCS), as a function of alloys type and different pHs. Galvanic corrosion tests were conducted in BCS at a pH of 7.6. Alloy surfaces were characterized using white-light interferometry (WLI) and scanning electron microscopy (SEM). The potentiodynamic test results exhibited the enhanced passive layer growth and a better corrosion resistance of Ti6Al4V compared to CoCrMo. Electrochemical impedance spectroscopy measurements demonstrated the influence of protein as a function of pH on corrosion mechanisms/kinetics. Galvanic coupling was not a major contributor to corrosion. SEM and WLI images demonstrated a significantly higher in surface roughness in CoCrMo after corrosion. The results of this study suggest that Ti6Al4V shows superior corrosion behaviour to CoCrMo due to its strong passive layer, simulated joint fluid components can affect the electrochemical nature of the metal/electrolyte interface as a function of pH, and the galvanic effect of coupling CoCrMo and Ti6Al4V in a single joint is weak. Published by Elsevier Ltd.

47 CFR 90.672 - Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part 22 Cellular Radiotelephone systems, and within the... Procedures and Process-Unacceptable Interference § 90.672 Unacceptable interference to non-cellular 800 MHz...

Oxidation of uranium and uranium alloys

International Nuclear Information System (INIS)

Orman, S.

1976-01-01

The corrosion behaviour of uranium in oxygen, water and water + oxygen mixtures is compared and contrasted. A considerable amount of work, much of it conflicting, has been published on the U + H 2 O and U + H 2 O + O 2 systems. An attempt has been made to summarise this data and to explain the reasons for the lack of agreement between the experimental results. The evidence for the mechanism involving OH - ion diffusion as the reacting entity in both the U + H 2 O and U + O 2 + H 2 O reactions is advanced. The more limited corrosion data on some lean uranium alloys and on some higher addition alloys referred to as stainless materials is summarised together with some previously unreported results obtained with these materials at AWRE. The data indicates that in the absence of oxygen the lean alloys behave in a similar manner to uranium and evolve hydrogen in approximately theoretical quantities. But the stainless alloys absorb most of the product hydrogen and assessments of reactivity based on hydrogen evolution would be very inaccurate. The direction that future corrosion work on these materials should take is recommended

The thermodynamic stability induced by solute co-segregation in nanocrystalline ternary alloys

Energy Technology Data Exchange (ETDEWEB)

Liang, Tao; Chen, Zheng; Zhang, Jinyong; Zhang, Ping [China Univ. of Mining and Technology, Xuzhou (China). School of Mateial Science and Engineering; Yang, Xiaoqin [China Univ. of Mining and Technology, Xuzhou (China). School of Chemical Engineering and Technology

2017-06-15

The grain growth and thermodynamic stability induced by solute co-segregation in ternary alloys are presented. Grain growth behavior of the single-phase supersaturated grains prepared in Ni-Fe-Pb alloy melt at different undercoolings was investigated by performing isothermal annealings at T = 400 C-800 C. Combining the multicomponent Gibbs adsorption equation and Guttmann's grain boundary segregation model, an empirical relation for isothermal grain growth was derived. By application of the model to grain growth in Ni-Fe-Pb, Fe-Cr-Zr and Fe-Ni-Zr alloys, it was predicted that driving grain boundary energy to zero is possible in alloys due to the co-segregation induced by the interactive effect between the solutes Fe/Pb, Zr/Ni and Zr/Cr. A non-linear relationship rather than a simple linear relation between 1/D* (D* the metastable equilibrium grain size) and ln(T) was predicted due to the interactive effect.

Electric charging/discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons.

Science.gov (United States)

Fukuhara, Mikio; Sugawara, Kazuyuki

2014-01-01

Charging/discharging behaviors of de-alloyed and anodic oxidized Ti-Ni-Si amorphous alloy ribbons were measured as a function of current between 10 pA and 100 mA, using galvanostatic charge/discharging method. In sharp contrast to conventional electric double layer capacitor (EDLC), discharging behaviors for voltage under constant currents of 1, 10 and 100 mA after 1.8 ks charging at 100 mA show parabolic decrease, demonstrating direct electric storage without solvents. The supercapacitors, devices that store electric charge on their amorphous TiO2-x surfaces that contain many 70-nm sized cavities, show the Ragone plot which locates at lower energy density region near the 2nd cells, and RC constant of 800 s (at 1 mHz), which is 157,000 times larger than that (5 ms) in EDLC.

Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

International Nuclear Information System (INIS)

Maziasz, P.J.; Klueh, R.L.

1988-01-01

Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some σ phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs

7 CFR 800.88 - Loss of identity.

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2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Loss of identity. 800.88 Section 800.88 Agriculture... Methods and Procedures § 800.88 Loss of identity. (a) Lots. Except as noted in paragraph (d) of this... personnel performing a reinspection, appeal inspection, or Board appeal inspection service, the identity of...

47 CFR 54.800 - Terms and definitions.

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2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Terms and definitions. 54.800 Section 54.800... SERVICE Interstate Access Universal Service Support Mechanism § 54.800 Terms and definitions. (a) Average... § 61.3(d) of this chapter, except that it includes exogenous changes in effect prior to the effective...

Analysis of LTE 800MHz Network Deployment Strategy%LTE 800MHz网络部署策略分析

Institute of Scientific and Technical Information of China (English)

余扬尧; 陈杨; 杨芙蓉

2016-01-01

Starting ifrst with the current mobile user development situation of the three operators, the paper analyzed the necessity of China telecom LTE 800 MHz network construction, the network coverage, terminal market, construction speed, the business competition, and etc., concluded the short-term, mid-term and long-term deployment strategy for LTE 800 MHz.%首先从当前三大运营商的移动业务用户发展情况入手，分析了中国电信LTE 800 MHz网络建设的必要性，对LTE 800 MHz的网络覆盖、终端市场、建设速度、业务竞争等几个方面进行分析，得出了LTE 800 MHz近、中、远期的部署策略。

Electrocatalysts of platinum, cobalt and nickel prepared by mechanical alloying for the oxygen reduction reaction in H2SO4 0.5M

International Nuclear Information System (INIS)

Garcia C, M.A.; Fernandez V, S.M.; Vargas G, J.R.

2007-01-01

Metallic powders of Pt, Co and Nickel were processed by mechanical alloyed and electrocatalysts were synthesized for the oxygen reduction reaction, applicable in fuel cells. The structural and morphological characterization was carried out using X-ray Diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the alloyed powders formed agglomerates that consist of crystalline particles of nano metric size. Its were obtained polarization curves by the Electrode of Rotational Disk technique in a solution of H 2 SO 4 0.5 M, used as electrolyte, to evaluate the electrocatalytic activity of mechanically alloyed powders. Tafel graphics were built to determine the kinetic parameters of each electro catalyst. The PtCoNi alloy exhibited the biggest electrocatalytic activity, with the smallest over potential for the oxygen reduction reaction. (Author)

Standard Practice for Use of Mattsson's Solution of pH 7.2 to Evaluate the Stress- Corrosion Cracking Susceptibility of Copper-Zinc Alloys

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

1.1 This practice covers the preparation and use of Mattsson's solution of pH 7.2 as an accelerated stress-corrosion cracking test environment for brasses (copper-zinc base alloys). The variables (to the extent that these are known at present) that require control are described together with possible means for controlling and standardizing these variables. 1.2 This practice is recommended only for brasses (copper-zinc base alloys). The use of this test environment is not recommended for other copper alloys since the results may be erroneous, providing completely misleading rankings. This is particularly true of alloys containing aluminum or nickel as deliberate alloying additions. 1.3 This practice is intended primarily where the test objective is to determine the relative stress-corrosion cracking susceptibility of different brasses under the same or different stress conditions or to determine the absolute degree of stress corrosion cracking susceptibility, if any, of a particular brass or brass component ...

Intergranular stresses in Incoloy-800

International Nuclear Information System (INIS)

Holden, T.M.; Holt, R.A.; Clarke, A.P.

1997-01-01

The generation of intergranular residual strains under uniaxial loading conditions in the plastic regime has been measured in detail by neutron diffraction in Incoloy-800. A relatively simple theory, based on the Taylor model, gives a good semiquantitative account of the magnitudes of the strains. The results clarify the interpretation of measurements made earlier on Incoloy-800 steam generator tubes. (author)

The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

Energy Technology Data Exchange (ETDEWEB)

Hankin, G.L.; Faulkner, R.G. [Loughborough Univ. (United Kingdom); Hamilton, M.L.; Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)

1997-08-01

The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within {+-}53 MPa. The accuracy of the correlation improves with increasing material strength, to within {+-} MPa for predicting tensile yield strengths in the range of 400-800 MPa.

Ultrasonic measurement of elastic moduli of 17-4 pH stainless steel and uranium -2 molybdenum from -400C to 8000C

International Nuclear Information System (INIS)

Gieske, J.H.

1980-10-01

Young's Modulus, shear modulus, and Poisson's ratio for 17-4 pH stainless steel and uranium -2 molybdenum are calculated from ultrasonic longitudinal and shear velocities determined from -40 0 C to 800 0 C. The ultrasonic velocities were determined at elevated temperatures using a through-transmission buffer rod arrangement. An indium-gallium slurry bond was used as an ultrasonic couplant between Cupernickel 10 alloy buffer rods and the specimen. Microstructural changes and phase transitions in the specimens are evident from the temperature dependence of the ultrasonic data. 10 figures, 3 tables

31 CFR 800.226 - U.S. business.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false U.S. business. 800.226 Section 800... TAKEOVERS BY FOREIGN PERSONS Definitions § 800.226 U.S. business. The term U.S. business means any entity... subsidiary is a U.S. business. Corporation A and its branch or subsidiary is each also a foreign person...

Nanoindentation on V–4Ti alloy irradiated by H and He ions

International Nuclear Information System (INIS)

Yang, Yitao; Zhang, Chonghong; Meng, Yancheng; Liu, Juan; Gou, Jie; Xian, Yongqiang; Song, Yin

2015-01-01

V–4Ti and V samples were irradiated by H/He ions with various energies to produce a damage plateau in the region from surface to the depth of 1.5 um at room temperature. Nanoindentation was performed to investigate the hardening behavior of the two materials under irradiation. It is found that the relation of maximum depth of plastic zone and indentation depth is not a fixed value. The maximum depth of plastic zone decreases with increase of damage level. Nix and Gao model was used to fit the measured hardness to obtain a hardness value H 0 excluding indentation size effect (ISE), which can be used to characterize the hardening effect induced by irradiation. After fitting the data of H 0 , it is found that there is an exponential relation between the H 0 and damage level for both the V–4Ti and V materials. When the damage level is higher than ∼0.2 dpa, the hardness increases slowly, this indicates a slow increase of pinning centers in samples at this damage level. Comparing the hardening fraction of V–4Ti and V samples, significant hardening can be seen for V sample, and it becomes severe especially at damage higher than ∼0.2 dpa. The irradiation hardening resistance property of V–4Ti alloy is better than that of pure V

Performance of V-Cr-Ti alloys in a hydrogen environment

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W. K.

2000-01-01

A systematic study is underway at Argonne National Laboratory to evaluate the mechanical properties of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake by the samples and with the resulting influence on microstructures and tensile properties of the alloys. Other variables examined are specimen cooling rate and synergistic effects, if any, of oxygen and hydrogen on tensile behavior of the alloys. Experiments were conducted to evaluate the effect of pH 2 in the range of 3 x 10 -6 and 1 torr on tensile properties of two V-Cr-Ti alloys. Up to pH 2 of 0.05 torr, negligible effect of H was observed on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed at 500 C to 1.0 torr of H 2 pressure. Preliminary data from sequential exposures of the materials to low-pO 2 and several low-pH 2 environments did not reveal adverse effects on the maximum engineering stress or on uniform and total elongation when the alloy contained ∼ 2,000 wppm O and 16 wppm H. Furthermore, tests in H 2 -exposed specimens, initially annealed at various temperatures, showed that grain-size variation by a factor of ∼ 2 had little or no effect on tensile properties. Also, specimen cooling rate had a small effect, if any, on the tensile properties of the alloy

Safety of panitumumab-IRDye800CW and cetuximab-IRDye800CW for fluorescence-guided surgical navigation in head and neck cancers.

Science.gov (United States)

Gao, Rebecca W; Teraphongphom, Nutte; de Boer, Esther; van den Berg, Nynke S; Divi, Vasu; Kaplan, Michael J; Oberhelman, Nicholas J; Hong, Steven S; Capes, Elissa; Colevas, A Dimitrios; Warram, Jason M; Rosenthal, Eben L

2018-01-01

Purpose: To demonstrate the safety and feasibility of leveraging therapeutic antibodies for surgical imaging. Procedures: We conducted two phase I trials for anti-epidermal growth factor receptor antibodies cetuximab-IRDye800CW (n=12) and panitumumab-IRDye800CW (n=15). Adults with biopsy-confirmed head and neck squamous cell carcinoma scheduled for standard-of-care surgery were eligible. For cetuximab-IRDye800CW, cohort 1 was intravenously infused with 2.5 mg/m 2 , cohort 2 received 25 mg/m 2 , and cohort 3 received 62.5 mg/m 2 . For panitumumab-IRDye800CW, cohorts received 0.06 mg/kg, 0.5 mg/kg, and 1 mg/kg, respectively. Electrocardiograms and blood samples were obtained, and patients were followed for 30 days post-study drug infusion. Results: Both fluorescently labeled antibodies had similar pharmacodynamic properties and minimal toxicities. Two infusion reactions occurred with cetuximab and none with panitumumab. There were no grade 2 or higher toxicities attributable to cetuximab-IRDye800CW or panitumumab-IRDye800CW; fifteen grade 1 adverse events occurred with cetuximab-IRDye800CW, and one grade 1 occurred with panitumumab-IRDye800CW. There were no significant differences in QTc prolongation between the two trials (p=0.8). Conclusions: Panitumumab-IRDye800CW and cetuximab-IRDye800CW have toxicity and pharmacodynamic profiles that match the parent compound, suggesting that other therapeutic antibodies may be repurposed as imaging agents with limited preclinical toxicology data.

Soft magnetic properties and damping parameter of (FeCo-Al alloy thin films

Directory of Open Access Journals (Sweden)

Isao Kanada

2017-05-01

Full Text Available For high frequency device applications, a systematic study of the soft magnetic properties and magnetization dynamics of (FeCo-Al alloy thin films has been carried out. A low effective damping parameter αeff of 0.002 and a high saturation magnetization of about 1,800 emu/cc are obtained at y=0.2∼0.3 for (Fe1-yCoy98Al2 alloy thin films deposited onto fused silica and MgO(100 at an ambient temperature during deposition. Those films are of the bcc structure with the orientation normal to the film plane. They possess a columnar structure, grown along the film normal. The column width is found to be about 20 nm for y=0.25. It is concluded that the (FeCo-Al thin films with a damping parameter as low as 0.002 and high saturation magnetization of about 1,800 emu/cc have been successfully fabricated, and that they are potential for future high frequency device applications.

Mechanical Alterations during 800-m Self-Paced Track Running.

Science.gov (United States)

Girard, Olivier; Millet, Gregoire P; Micallef, Jean-Paul

2017-04-01

We assessed the time course of running mechanical alterations during an 800-m. On a 200-m indoor track, 18 physical education students performed an 800-m self-paced run. Once per lap, ground reaction forces were measured by a 5-m-long force platform system, and used to determine running kinetics/kinematics and spring-mass characteristics. Compared with 100 m (19.4±1.8 km.h -1 ) running velocity progressively decreased at 300, 500 m but levelled-off at 700 m marks (-5.7±4.6, -10.4±8.3, and -9.1±13.5%, respectively; Ppush-off forces (-5.1±7.2%, P0.05) and leg compression (+2.8±3.9%; P>0.05) remained unchanged, whereas centre of mass vertical displacement (+24.0±7.0%; P0.05). During an 800 m by physical education students, highest running velocity was achieved early during the run, with a progressive decrease in the second half of the trial. While vertical ground force characteristics remained unchanged, non-specialist runners produced lower peak braking and push-off forces, in turn leading to shorter stride length. Spring-mass model characteristics changed toward lower vertical stiffness values, whereas leg stiffness did not change. © Georg Thieme Verlag KG Stuttgart · New York.

Nonequilibrium synthesis of NbAl3 and Nb-Al-V alloys by laser cladding. II - Oxidation behavior

Science.gov (United States)

Haasch, R. T.; Tewari, S. K.; Sircar, S.; Loxton, C. M.; Mazumder, J.

1992-01-01

Isothermal oxidation behaviors of NbAl3 alloy synthesized by laser cladding were investigated at temperatures between 800 and 1400 C, and the effect of vanadium microalloying on the oxidation of the laser-clad alloy was examined. The oxidation kinetics of the two alloys were monitored using thermal gravimetric weight gain data, and the bulk and surface chemistries were analyzed using XRD and XPS, respectively. It was found that NbAl3 did not form an exclusive layer of protective Al2O3. The oxidation products at 800 C were found to be a mixture of Nb2O5 and Al2O3. At 1200 C, a mixture of NbAlO4, Nb2O5, and Al2O3 formed; and at 1400 C, a mixture of NbAlO4, Al2O3, NbO2, NbO(2.432), and Nb2O5 formed. The addition of V led to a dramatic increase of the oxidation rate, which may be related to the formation of (Nb, V)2O5 and VO2, which grows in preference to protective Al2O3.

Annealing effect on redistribution of atoms in austenite of Fe-Ni-Mo and Fe-Ni-Si alloys

International Nuclear Information System (INIS)

Rodionov, Yu.L.; Isfandiyarov, G.G.; Zambrzhitskij, V.N.

1980-01-01

Using the Moessbauer spectrum method, studied has been the change in the fine atomic structure of the Fe-(28-36)%Ni austenite alloys with Mo and Si additives during annealing in the 200-800 deg C range. Also, the energy of the activation of processes, occurring at the annealing temperatures of below 500 deg C has been researched. On the basis of the obtained results a conclusion is drawn that the annealing of the investigated alloys at 300-500 deg C is conducive to the redistribution of the atoms of the alloying element and to the formation of regions with a higher content of Ni and Mo(Si) atoms

First Principles Study of Adsorption of Hydrogen on Typical Alloying Elements and Inclusions in Molten 2219 Al Alloy

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Yu Liu

2017-07-01

Full Text Available To better understand the effect of the components of molten 2219 Al alloy on the hydrogen content dissolved in it, the H adsorption on various positions of alloying element clusters of Cu, Mn and Al, as well as the inclusion of Al2O3, MgO and Al4C3, were investigated by means of first principles calculation, and the thermodynamic stability of H adsorbed on each possible site was also studied on the basis of formation energy. Results show that the interaction between Al, MgO, Al4C3 and H atoms is mainly repulsive and energetically unfavorable; a favorable interaction between Cu, Mn, Al2O3 and H atoms was determined, with H being more likely to be adsorbed on the top of the third atomic layer of Cu(111, the second atomic layer of Mn(111, and the O atom in the third atomic layer of Al2O3, compared with other sites. It was found that alloying elements Cu and Mn and including Al2O3 may increase the hydrogen adsorption in the molten 2219 Al alloy with Al2O3 being the most sensitive component in this regard.

Corrosion of Inconel-625, Hastelloy-X280 and Incoloy-800 in 550 - 750°C superheated steam. Influence of alloy heat treatment, surface treatment, steam temperature and steam velocity. Part I: Results up to 6000 hours exposure time. RCN Report

International Nuclear Information System (INIS)

Tilborg, P.J. van; Linde, A. van der

1969-10-01

Sheet samples of Inconel-625, Hastelloy-X280 and Incoloy-800 were tested, in the solution annealed and in the solution annealed + 20% cold worked + 800°C tempered condition, in steam with a velocity of 5 m/sec. at 550, 650 and 750°C and in steam with a volocity of 15 and 85 m/sec. at 550°C. At 550°C and 750°C the samples were tested in the heat treated, annealed or tempered and the heat treated + electropolished condition. At 650°C moreover as heat treated + ground and pickled samples were tested. Post-corrosion sample investigations involved measurement of the adherent oxide thickness, the total amount of corroded metal, the metal loss to system, and the metallographic and microprobe investigation of the adherent oxide film and adjacent diffusion disturbed alloy layer. The results obtained up to 6000 hours exposure time showed that the surface treatment has a decisive influence on the corrosion behaviour of all three alloys tested. The differences in the corrosion data for the two heat treatment conditions are small. The influence of the steam velocity, as tested at 550°C, on the initial corrosion rate was surprisingly high, while the long-term linear corrosion rates are only slightly influenced by the gas velocity. In general the linear corrosion rates were low, 1-5 mg/dm 2 month, and not consistently affected by the test-temperature. The metal loss to system values were 2 <15 mg/dm 2 in the low velocity steam at all three test temperatures and <30 mg/dm 2 in the high velocity steam at 550°C. The metallographic and microprobe examinations revealed no remarkable results, as compared with the results of analogous tests reported in literature. (author)

800 C Silicon Carbide (SiC) Pressure Sensors for Engine Ground Testing

Science.gov (United States)

Okojie, Robert S.

2016-01-01

MEMS-based 4H-SiC piezoresistive pressure sensors have been demonstrated at 800 C, leading to the discovery of strain sensitivity recovery with increasing temperatures above 400 C, eventually achieving up to, or near, 100 recovery of the room temperature values at 800 C. This result will allow the insertion of highly sensitive pressure sensors closer to jet, rocket, and hypersonic engine combustion chambers to improve the quantification accuracy of combustor dynamics, performance, and increase safety margin. Also, by operating at higher temperature and locating closer to the combustion chamber, reduction of the length (weight) of pressure tubes that are currently used will be achieved. This will result in reduced costlb to access space.

Identification of a cast iron alloy containing nonstrategic elements

Science.gov (United States)

Cooper, C. V.; Anton, D. L.; Lemkey, F. D.; Nowotny, H.; Bailey, R. S.; Favrow, L. H.; Smeggil, J. G.; Snow, D. B.

1989-01-01

A program was performed to address the mechanical and environmental needs of Stirling engine heater head and regenerator housing components, while reducing the dependence on strategic materials. An alloy was developed which contained no strategic elemental additions per se. The base is iron with additions of manganese, molybdenum, carbon, silicon, niobium, and ferro-chromium. Such an alloy should be producible on a large scale at very low cost. The resulting alloy, designated as NASAUT 4G-Al, contained 15 Mn, 15 Cr, 2 Mo, 1.5 C, 1.0 Si, 1.0 Nb (in weight percent) with a balance of Fe. This alloy was optimized for chemistry, based upon tensile strength, creep-rupture strength, fracture behavior, and fatigue resistance up to 800 C. Alloys were also tested for environmental compatibility. The microstructure and mechanic properties (including hardness) were assessed in the as-cast condition and following several heat treatments, including one designed to simulate a required braze cycle. The alloy was fabricated and characterized in the form of both equiaxed and columnar-grained castings. The columnar grains were produced by directional solidification, and the properties were characterized in both the longitudinal and transverse orientations. The NASAUT 4G-Al alloy was found to be good in cyclic-oxidation resistance and excellent in both hydrogen and hot-corrosion resistance, especially in comparison to the baseline XF-818 alloy. The mechanical properties of yield strength, stress-rupture life, high-cycle-fatigue resistance, and low-cycle-fatigue resistance were good to excellent in comparison to the current alloy for this application, HS-31 (X-40), with precise results depending in a complex manner on grain orientation and temperature. If required, the ductility could be improved by lowering the carbon content.

Amorphization of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition

Energy Technology Data Exchange (ETDEWEB)

Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Pană, O. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

2016-11-01

Amorphization of Fe{sub 75}Si{sub 20}B{sub 5} (at.%) alloy has been attempted both by wet and dry mechanical alloying starting from a mixture of elemental powders. Powder amorphization was not achieved even after 140 hours of dry mechanical alloying. Using the same milling parameters, when wet mechanical alloying was used, the powder amorphization was achieved after 40 h of milling. Our assumption regarding the powder amorphization capability enhancement by contamination with carbon was proved by X-ray Photoelectron Spectroscopy (XPS) measurements which revealed the presence of carbon in the chemical composition of the wet mechanically alloyed sample. Using shorter milling times and several process control agents (PCA) (ethanol, oleic acid and benzene) with different carbon content it was proved that the milling duration required for powder amorphization is linked to the carbon content of the PCA. Differential Scanning Calorimetry (DSC), thermomagnetic (TG) and X-ray Diffraction (XRD) measurements performed to the heated samples revealed the fact that, the crystallisation occurs at 488 °C, thus leading to the formation of Fe{sub 3}Si and Fe{sub 2}B. Thermogravimetry measurements performed under H{sub 2} atmosphere, showed the same amount of contamination with C, which is about 2.3 wt%, for the amorphous samples regardless of the type of PCA. Saturation magnetisation of the wet milled samples decreases upon increasing milling time. In the case of the amorphous samples wet milled with benzene up to 20 h and with oleic acid up to 30 h, the saturation magnetisation has roughly the same value, indicating the same degree of contamination. The XRD performed on the samples milled using the same parameters, revealed that powder amorphization can be achieved even via dry milling, just by adding the equivalent amount of elemental C calculated from the TG plots. This proves that in this system by considering the atomic species which can contaminate the powder, they can be

Structural conditions of achieving maximum ductility of two-phase Ni-NiO alloys

International Nuclear Information System (INIS)

Grabin, V.V.; Dabizha, E.V.; Movchan, B.A.

1984-01-01

A study was made on possibility of increasing ductility of two-phase Ni-NiO alloys, proJuced by traditional technology: ingot smelting, rolling and corresponding annealing for production of grain with certain size. The correlation of mechanical properties of Ni-NiO alloys and pure nickel shows that completion of the structural conJition D--lambda (where D - the average grain diameter, lambda - the value of free path between particles) in two-phase alloys enables: to increase the ultimate strength 1.5 times and preserve the basic level of pure nickel plasticity - at 20 deg C; to increase plasticity 1.4-1.5 times with preserved basic level of pure nickel plasticity - at 800 deg C. The conclusions testify to possibility of controlling mechanical properties of two-phase alloys using structural D and lambda parameters It is proposed that creation of structures with more unifor m particle distribution with respect to sizes will the accompanied by further increase of plasticity under D=lambda condition

Determination of an instability temperature for alloys in the cooling gas of a high temperature reactor

International Nuclear Information System (INIS)

Grimmer, H.; Grman, D.; Krompholz, K.; Zimmermann, U.; Ullrich, G.

1985-05-01

High temperature alloys designed to be used for components in the primary circuit of a helium cooled high temperature nuclear reactor show massive CO production above a certain temperature, called the instability temperature T/sub i/, which increases with increasing partial pressure of CO in the cooling gas. At p/sub CO/ = 15 microbar, T/sub i/ lies between 900 and 950 degrees C for the four alloys under investigation: T/sub i/ is lowest for the iron base alloy Incoloy 800 H and increases for the nickel base alloys in the order Inconel 617, HDA 230 and Nimonic 86. Measurements of T/sub i/ made at 3 different laboratories were compared and shown to agree for p/sub CO/ 25 microbar, compatible with CO production by a reaction of Cr2O3 with carbides. Some measurements of T/sub i/ on HDA 230 and Nimonic 86 were performed in the course of simulated reactor disturbances. They showed that the oxide layer looses its protective properties above T/sub i/. A highlight of the examinations was the detection of eta-carbides (M6C) with unusual properties. M6C is the only type of carbide occuring in HDA 230. An eta-carbide with a lattice constant of 1088.8 pm had developed at the surface of Nimonic 86 during pre-oxidation before the disturbance simulation. Its composition is estimated at Ni3SiMo2C. Eta-carbides containing Si and especially eta-carbides with lattice constants as low as 1088.8 pm have been described only rarely until now. (author)

Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

Science.gov (United States)

Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

2017-12-01

Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

Phase transition and hydrogen storage properties of Mg–Ga alloy

International Nuclear Information System (INIS)

Wu, Daifeng; Ouyang, Liuzhang; Wu, Cong; Wang, Hui; Liu, Jiangwen; Sun, Lixian; Zhu, Min

2015-01-01

Highlights: • A fully reversible transformation in Mg–Ga–H system with reduced dehydrogenation enthalpy is realized. • The mechanism of phase transformation in the de/hydrogenation of Mg–Ga alloy is revealed. • The de/hydrogenation process of Mg 5 Ga 2 compound is expressed as: Mg 5 Ga 2 + H 2 ↔ 2Mg 2 Ga + MgH 2 . - Abstract: Mg-based alloys are viewed as one of the most promising candidates for hydrogen storage; however, high desorption temperature and the sluggish kinetics of MgH 2 hinder their practical application. Alloying and changing the reaction pathway are effective methods to solve these issues. As the solid solubility of Ga in Mg is 5 wt% at 573 K, the preparation of a Mg(Ga) solid solution at relatively high temperatures was designed in this paper. The phase transition and hydrogen storage properties of the MgH 2 and Mg 5 Ga 2 composite (hereafter referred to as Mg–Ga alloy) were investigated by X-ray diffraction (XRD), pressure–composition-isotherm (PCI) measurements, and differential scanning calorimetry (DSC). The reversible hydrogen storage capacity of Mg–Ga alloy is 5.7 wt% H 2 . During the dehydrogenation process of Mg–Ga alloy, Mg 2 Ga reacts with MgH 2 , initially releasing H 2 and forming Mg 5 Ga 2 ; subsequently, MgH 2 decomposes into Mg with further release of H 2 . The phase transition mechanism of the Mg 5 Ga 2 compound during the dehydrogenation process was also investigated by using in situ XRD analysis. In addition, the dehydrogenation enthalpy and entropy changes, and the apparent activation energy were also calculated

Creep-Data Analysis of Alloy 617 for High Temperature Reactor Intermediate Heat Exchanger

International Nuclear Information System (INIS)

Kim, Woo Gon; Ryu, Woo Seog; Kim, Yong Wan; Yin, Song Nan

2006-01-01

The design of the metallic components such as hot gas ducts, intermediate heat exchanger (IHX) tube, and steam reformer tubes of very high temperature reactor (VHTR) is principally determined by the creep properties, because an integrity of the components should be preserved during a design life over 30 year life at the maximum operating temperature up to 1000 .deg. C. For designing the time dependent creep of the components, a material database is needed, and an allowable design stress at temperature should be determined by using the material database. Alloy 617, a nicked based superalloy with chromium, molybdenum and cobalt additions, is considered as a prospective candidate material for the IHX because it has the highest design temperature. The alloy 617 is approved to 982 .deg. C (1800 .deg. F) and other alloys approved to 898 .deg. C (1650 .deg. C), such as alloy 556, alloy 230, alloy HX, alloy 800. Also, the alloy 617 exhibits the highest level of creep strength at high temperatures. Therefore, it is needed to collect the creep data for the alloy 617 and the creep-rupture life at the given conditions of temperature and stress should be predicted for the IHX construction. In this paper, the creep data for the alloy 617 was collected through literature survey. Using the collected data, the creep life for the alloy 617 was predicted based on the Larson-Miller parameter. Creep master curves with standard deviations were presented for a safety design, and failure probability for the alloy 617 was obtained with a time coefficient

Study of superficial films and of electrochemical behaviour of some nickel base alloys and titanium base alloys in solution representation of granitic, argillaceous and salted ground waters

International Nuclear Information System (INIS)

Quang, K.V.; Da Cunha Belo, M.; Benabed, M.S.; Bourelier, F.; Jallerat, N.; Pari, F.L.

1985-01-01

The corrosion behaviour of the stainless steels 304, 316 Ti, 25Cr-20Ni-Mo-Ti, nickel base alloys Hastelloy C4, Inconel 625, Incoloy 800, Ti and Ti-0.2% Pd alloy has been studied in the aerated or deaerated solutions at 20 0 C and 90 0 C whose compositions are representative of interstitial ground waters: granitic or clay waters or salt brine. The electrochemical techniques used are voltametry, polarization resistance and complexe impedance measurements. Electrochemical data show the respective influence of the parameters such as temperature, solution composition and dissolved oxygen, addition of soluble species chloride, fluoride, sulfide and carbonates, on which depend the corrosion current density, the passivation and the pitting potential. The inhibition efficiency of carbonate and bicarbonate activities against pitting corrosion is determined. In clay water at 90 0 C, Ti and Ti-Pd show very high passivation aptitude and a broad passive potential range. Alloying Pd increases cathodic overpotential and also transpassive potential. It makes the alloy less sensitive to the temperature effect. Optical Glow Discharge Spectra show three parts in the composition depth profiles of surface films on alloys. XPS and SIMS spectrometry analyses are also carried out. Electron microscopy observation shows that passive films formed on Ti and Ti-Pd alloy have amorphous structure. Analysis of the alloy constituents dissolved in solutions, by radioactivation in neutrons, gives the order of magnitude of the Ni base alloy corrosion rates in various media. It also points out the preferential dissolution of alloying iron and in certain cases of chromium

Effect of current density and pH in obtaining the Ni-Fe alloy by electrodeposition; Efeito da densidade de corrente e pH na obtencao da liga Ni-Fe por eletrodeposicao

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Jose Anderson Machado; Raulino, Anamelia de Medeiros Dantas; Raulino, Jose Leonardo Costa; Campos, Ana Regina Nascimento; Prasad, Shiva; Santana, Renato Alexandre Costa de, E-mail: jmo.anderson@gmail.com, E-mail: anameliadantas@yahoo.com.br, E-mail: leonardo.jcr@hotmail.com, E-mail: arncampos@yahoo.com.br, E-mail: prasad@deq.ufcg.edu.br, E-mail: renatoacs@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Lab. de Eletroquimica e Corrosao

2017-01-15

Metallic coatings can be applied for different purposes, for example to improve the mechanical, catalytic, anti corrosive properties or simply to improve the decorative appearance. In the work the Fe-Ni alloys have been obtained by electrodeposition process using a simple electrolytic bath containing the reagents, nickel sulfate, iron sulfate and sodium tartrate. A complete experimental design 2{sup 2} , associated with the response surface methodology (RSM) technique was used as optimization tool. Chemical composition, current efficiency, surface morphology and electrochemical corrosion measures were performed. It was observed that a decrease in the pH favored an increase in iron and decrease in nickel contents in the alloy. The iron content influenced the alloy morphology. The best experiment showed an average corrosion resistance 5471.5 Ω.cm² and a corrosion current density 4.814x10{sup -6} A/cm². This experiment presented a composition of 70 wt% Ni and 30 wt% Fe in the alloy and an average deposition current efficiency of 58.7%. (author)

Electronic Transport Behaviors due to Charge Density Waves in Ni-Nb-Zr-H Glassy Alloys

Science.gov (United States)

Fukuhara, Mikio; Umemori, Yoshimasa

2013-11-01

The amorphous Ni-Nb-Zr-H glassy alloy containing subnanometer-sized icosahedral Zr5 Nb5Ni3 clusters exhibited four types of electronic phenomena: a metal/insulator transition, an electric current-induced voltage oscillation (Coulomb oscillation), giant capacitor behavior and an electron avalanche with superior resistivity. These findings could be excluded by charge density waves that the low-dimensional component of clusters, in which the atoms are lined up in chains along the [130] direction, plays important roles in various electron transport phenomena.

Development and evaluation of a magnesium-zinc-strontium alloy for biomedical applications--alloy processing, microstructure, mechanical properties, and biodegradation.

Science.gov (United States)

Guan, Ren-guo; Cipriano, Aaron F; Zhao, Zhan-yong; Lock, Jaclyn; Tie, Di; Zhao, Tong; Cui, Tong; Liu, Huinan

2013-10-01

A new biodegradable magnesium-zinc-strontium (Mg-Zn-Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy processing (casting, rolling, and heat treatment), microstructures, mechanical properties, and degradation properties in simulated body fluid (SBF). Aging treatment of the ZSr41 alloy at 175 °C for 8h improved the mechanical properties when compared to those of the as-cast alloy. Specifically, the aged ZSr41 alloy had an ultimate tensile strength of 270 MPa, Vickers hardness of 71.5 HV, and elongation at failure of 12.8%. The mechanical properties of the ZSr41 alloy were superior as compared with those of pure magnesium and met the requirements for load-bearing medical implants. Furthermore, the immersion of the ZSr41 alloy in SBF showed a degradation mode that progressed cyclically, alternating between pitting and localized corrosion. The steady-state average degradation rate of the aged ZSr41 alloy in SBF was 0.96 g/(m(2)·hr), while the pH of SBF immersion solution increased. The corrosion current density of the ZSr41 alloy in SBF solution was 0.41 mA/mm(2), which was much lower than 1.67 mA/mm(2) for pure Mg under the same conditions. In summary, compared to pure Mg, the mechanical properties of the new ZSr41 alloy improved while the degradation rate decreased due to the addition of Zn and Sr alloying elements and specific processing conditions. The superior mechanical properties and corrosion resistance of the new ZSr41 alloy make it a promising alloy for next-generation implant applications. Copyright © 2013 Elsevier B.V. All rights reserved.

31 CFR 800.207 - Covered transaction.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Covered transaction. 800.207 Section 800.207 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF..., which could result in control of a U.S. business by a foreign person. ...

BN-800 - history and perspective

International Nuclear Information System (INIS)

Krivitski, I.Yu.

2001-01-01

The sodium cooled fast reactors are one of the most developed and advanced directions of future nuclear engineering. Russia is the first among other countries in field of fast reactor development. The idea of fast reactor designing was proposed in the former Soviet Union by Dr. A.I. Leipunski at the end of 40 th . The successful operation of Russian fast reactors (BOR-60, BN-350 and BN-600 and the world experience proved the feasibility, reliability and safety of this direction of nuclear engineering and allowed to begin the development of the BN-800 reactor project as the commercial fast reactor. In 1992 Russian Government confirmed the construction of BN-800 reactors on South Ural NPP in Chelyabinsk region and on Beloyarskaya NPP. This report presents the brief review on main directions of BN-800 reactor development carrying out in IPPE. (authors)

Theoretical Studies of Hydrogen Storage Alloys.

Energy Technology Data Exchange (ETDEWEB)

Jonsson, Hannes

2012-03-22

Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgH{sub 2} is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i) the binding energy of the hydrogen atoms in the hydride is too large, causing the release temperature to be too high, and (ii) the diffusion of hydrogen through the hydride is so slow that loading of hydrogen into the metal takes much too long. In the first year of the project, we found that the addition of ca. 15% of aluminum decreases the binding energy to the hydrogen to the target value of 0.25 eV which corresponds to release of 1 bar hydrogen gas at 100 degrees C. Also, the addition of ca. 15% of transition metal atoms, such as Ti or V, reduces the formation energy of interstitial H-atoms making the diffusion of H-atoms through the hydride more than ten orders of magnitude faster at room temperature. In the second year of the project, several calculations of alloys of magnesium with various other transition metals were carried out and systematic trends in stability, hydrogen binding energy and diffusivity established. Some calculations of ternary alloys and their hydrides were also carried out, for example of Mg{sub 6}AlTiH{sub 16}. It was found that the binding energy reduction due to the addition of aluminum and increased diffusivity due to the addition of a transition metal are both effective at the same time. This material would in principle work well for hydrogen storage but it is, unfortunately, unstable with respect to phase separation. A search was made for a ternary alloy of this type where both the alloy and the corresponding hydride are stable. Promising results were obtained by including Zn in the alloy.

31 CFR 800.208 - Critical infrastructure.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Critical infrastructure. 800.208 Section 800.208 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... infrastructure means, in the context of a particular covered transaction, a system or asset, whether physical or...

The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

International Nuclear Information System (INIS)

Hankin, G.L.; Faulkner, R.G.; Hamilton, M.L.; Garner, F.A.

1997-01-01

The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within ±53 MPa. The accuracy of the correlation improves with increasing material strength, to within ± MPa for predicting tensile yield strengths in the range of 400-800 MPa

Long-term behaviour of heat-resistant steels and high-temperature materials

International Nuclear Information System (INIS)

1987-01-01

This book contains 10 lectures with the following subjects: On the effect of thermal pretreatment on the structure and creep behaviour of the alloy 800 H (V. Guttmann, J. Timm); Material properties of heat resistant ferritic and austenitic steels after cold forming (W. Bendick, H. Weber); Investigations for judging the working behaviour of components made of alloy 800 and alloy 617 under creep stress (H.J. Penkalla, F. Schubert); Creep behaviour of gas turbine materials in hot gas (K.H. Kloos et al.); Effect of small cold forming on the creep beahviour of gas turbine blades made of Nimonic 90 (K.H. Keienburg et al.); Investigations on creep fatigue alternating load strength of nickel alloys (G. Raule); Change of structure, creep fatigue behaviour and life of X20 Cr Mo V 12 1 (by G. Eggeler et al.); Investigations on thermal fatigue behaviour (K.H. Mayer et al.); Creep behaviour of similar welds of the steels 13 Cr Mo 4 4, 14 MoV 6 3, 10 Cr Mo 910 and GS-17 Cr Mo V 5 11 (K. Niel et al.); Determining the creep crack behaviour of heat resistant steels with samples of different geometry (K. Maile, R. Tscheuschner). (orig.,/MM) [de

Mechanochemical synthesis of nanocrystalline Fe and Fe–B magnetic alloys

International Nuclear Information System (INIS)

Mohammadi, Majid; Ghasemi, Ali; Tavoosi, Majid

2016-01-01

Mechanochemical synthesis and magnetic characterization of nanocrystalline Fe and Fe–B magnetic alloys was the goal of this study. In this regard, different Fe_2O_3–B_2O_3 powder mixtures with sufficient amount of CaH_2 were milled in a planetary ball mill in order to produce nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that, nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys can be successfully synthesized by the reduction reaction of Fe_2O_3 and B_2O_3 with CaH_2 during mechanical alloying. The structure of produced Fe_9_5B_5 and Fe_8_5B_1_5 alloys was a combination of Fe and Fe_2B phases with average crystallite sizes of about 15 and 10 nm, respectively. The produced nanocrystalline alloys exhibited soft magnetic properties with the coercivity and saturation of magnetization in the range of 170–240 Oe and 9–28 emu/g, respectively. Increasing the boron content has a destructive effect on soft magnetic properties of Fe–B alloys. - Highlights: • We study the mechanochemical synthesis of nanocrystalline boron, Fe and Fe–B alloys. • We study the reduction reaction of B_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–B_2O_3–CaH_2 during milling. • We study the effect of B on magnetic properties of nanocrystalline Fe–B alloys.

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

Directory of Open Access Journals (Sweden)

Wolf-Dieter Mueller

2014-06-01

Full Text Available Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

Solubility of apatite in H2O-NaCl and silicate-bearing solutions at 0.7-3.0 GPa, 800° C

Science.gov (United States)

Antignano, A.; Manning, C. E.

2004-12-01

Apatite is a major reservoir for the rare-earth elements (REE) in the earth's crust. However, little is known about its solubility in metamorphic fluids. We measured the solubility of apatite in H2O-NaCl and silicate bearing fluids at 800° C and 1.0-2.0 GPa using a piston-cylinder apparatus with NaCl-graphite furnaces. A single Durango fluor-apatite crystal was loaded into a 1.6 mm OD Pt inner capsule, which was crimped and then placed in a 3.5 OD Pt outer capsule with ultra pure H2O and NaCl or powdered albite. Solubility was determined by the weight loss of the apatite grain after 24 hrs. In the H2O-NaCl experiments, total dissolved solids (TDS) were initially below detection (0.4 millimolal) between XNaCl= 0 and XNaCl= 0.025. At XNaCl= 0.035, solubility was 3.3(0.2) millimolal (errors are 1s), and it increased to 57.5(0.4) millimolal at XNaCl= 0.526. Our results show that there is an enhancement in apatite solubility with increasing pressure in pure H2O. Solubility is initially below detection at bearing solutions. This probably explains textures in which monazite mantles apatite, which are common in granulite metamorphic terranes, such as the Kiirunavaara magnetite-apatite ore.

31 CFR 800.212 - Foreign entity.

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2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Foreign entity. 800.212 Section 800.212 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... business is outside the United States or its equity securities are primarily traded on one or more foreign...

10 CFR 800.306 - Noninterference with other laws.

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2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Noninterference with other laws. 800.306 Section 800.306 Energy DEPARTMENT OF ENERGY LOANS FOR BID OR PROPOSAL PREPARATION BY MINORITY BUSINESS ENTERPRISES SEEKING DOE CONTRACTS AND ASSISTANCE Loan Administration § 800.306 Noninterference with other laws...

30 CFR 75.800-1 - Circuit breakers; location.

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2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Circuit breakers; location. 75.800-1 Section 75.800-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY... § 75.800-1 Circuit breakers; location. Circuit breakers protecting high-voltage circuits entering an...

Corrosion of austenitic and ferritic-martensitic steels exposed to supercritical carbon dioxide

International Nuclear Information System (INIS)

Tan, L.; Anderson, M.; Taylor, D.; Allen, T.R.

2011-01-01

Highlights: → Oxidation is the primary corrosion phenomenon for the steels exposed to S-CO 2 . → The austenitic steels showed significantly better corrosion resistance than the ferritic-martensitic steels. → Alloying elements (e.g., Mo and Al) showed distinct effects on oxidation behavior. - Abstract: Supercritical carbon dioxide (S-CO 2 ) is a potential coolant for advanced nuclear reactors. The corrosion behavior of austenitic steels (alloys 800H and AL-6XN) and ferritic-martensitic (FM) steels (F91 and HCM12A) exposed to S-CO 2 at 650 deg. C and 20.7 MPa is presented in this work. Oxidation was identified as the primary corrosion phenomenon. Alloy 800H had oxidation resistance superior to AL-6XN. The FM steels were less corrosion resistant than the austenitic steels, which developed thick oxide scales that tended to exfoliate. Detailed microstructure characterization suggests the effect of alloying elements such as Al, Mo, Cr, and Ni on the oxidation of the steels.

Comparative Study by MS and XRD of Fe50Al50 Alloys Produced by Mechanical Alloying, Using Different Ball Mills

International Nuclear Information System (INIS)

Rojas Martinez, Y.; Perez Alcazar, G. A.; Bustos Rodriguez, H.; Oyola Lozano, D.

2005-01-01

In this work we report a comparative study of the magnetic and structural properties of Fe 50 Al 50 alloys produced by mechanical alloying using two different planetary ball mills with the same ball mass to powder mass relation. The Fe 50 Al 50 sample milled during 48 h using the Fritsch planetary ball mill pulverisette 5 and balls of 20 mm, presents only a bcc alloy phase with a majority of paramagnetic sites, whereas that sample milled during the same time using the Fritsch planetary ball mill pulverisette 7 with balls of 15 mm, presents a bcc alloy phase with paramagnetic site (doublet) and a majority of ferromagnetic sites which include pure Fe. However for 72 h of milling this sample presents a bcc paramagnetic phase, very similar to that prepared with the first system during 48 h. These results show that the conditions used in the first ball mill equipment make more efficient the milling process.

31 CFR 800.303 - Lending transactions.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Lending transactions. 800.303 Section 800.303 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... the creation in the foreign person of a secured interest in securities or other assets of the U.S...

The role of iridium in the work-function behavior of dilute-solution tungsten, iridium alloys

International Nuclear Information System (INIS)

D'Cruz, L.A.

1991-01-01

Requirements of thermionic electrode materials have emphasized the need for substantial improvements in microstructural stability, strength and creep resistance at service temperatures in excess of 2,500K. This study utilized both chemical alloying and mechanical alloying procedures for the addition of iridium to submicron W powder followed by cold compaction and sintering. The shrinkage characteristics and microstructural development were studied in iridium-added tungsten compacts with a range of additive levels. An electron-emission study was subsequently carried out in order to evaluate the work-function behavior of the consolidated alloys. The work function was obtained from current-emission measurements from the electrode surface under UHV conditions in the temperature range of 1,800 to 2,500K using a Vacuum Emission Vehicle (VEV). The data show that the magnitude of the work function in these alloys varied with temperature and was sensitive to sub-surface iridium content

Bubble formation in Zr alloys under heavy ion implantation

Energy Technology Data Exchange (ETDEWEB)

Pagano, L. Jr.; Motta, A.T. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Nuclear Engineering; Birtcher, R.C. [Argonne National Lab., IL (United States). Materials Science Div.

1995-12-01

Kr ions were used in the HVEM/Tandem facility at ANL to irradiate several Zr alloys, including Zircaloy-2 and -4, at 300-800 C to doses up to 2{times}10{sup 16}ion.cm{sup -2}. Both in-situ irradiation of thin foils as well as irradiation of bulk samples with an ion implanter were used in this study. For the thin foil irradiations, a distribution of small bubbles in the range of 30-100 {angstrom} was found at all temperatures with the exception of the Cr-rich Valloy where 130 {angstrom} bubbles were found. Irradiation of bulk samples at 700-800 C produced large faceted bubbles up to 300 {angstrom} after irradiation to 2{times}10{sup 16}ion.cm{sup -2}. Results are examined in context of existing models for bubble formation and growth in other metals.

7 CFR 800.116 - How to request original services.

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2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false How to request original services. 800.116 Section 800... Original Services § 800.116 How to request original services. (a) General. Except as otherwise provided for in § 800.117, requests for original services shall be filed with an agency or field office authorized...

7 CFR 800.199 - Conflict-of-interest provisions.

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2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Conflict-of-interest provisions. 800.199 Section 800... Delegations, Designations, Approvals, Contracts, and Conflicts of Interest § 800.199 Conflict-of-interest...) Prohibited conflicts of interest. Unless waived on a case-by-case basis by the Administrator under section 11...

Structural evolution of a 2205 duplex stainless steel between 500 C and 800 C and pitting corrosion resistance

International Nuclear Information System (INIS)

Kordatos, J.D.; Papadimitriou, G.; Fourlaris, G.

1999-01-01

The cooling rate of a duplex stainless steel from high temperature (region of stability of α-ferrite) down to the ambient temperature is critical for the mutual formation of its constituent phases, i.e. ferrite and austenite, and for their content in alloying elements. Therefore it is expected that cooling rates will affect indirectly the transformation and precipitation phenomena occuring during subsequent heat treatment. The aim of this study is to investigate the influence of the cooling rate on the transformation behavior of a SAF 2205 duplex stainless steel subjected to heat treatments in the temperature range between 500 C to 800 C. The specimens were solution annealed at 1100 C and then cooled in air, oil or water. They were subsequently subjected to isothermal heat treatment for 5 hours at temperatures of 500, 600, 700 and 800 C. The structural evolution was investigated using several techniques, among them optical, scanning and transmission electron microscopy coupled with extensive EDS X-ray microanalysis and selected area electron diffraction pattern analysis. (orig.)

A Study of Protection of Copper Alloys

International Nuclear Information System (INIS)

Kim, E. A.; Kim, S. H.; Kim, C. R.

1974-01-01

Volatile treatment of high capacity boiler water with hydrazine and ammonia is studied. Ammonia comes from the decomposition of excess hydrazine injected to treat dissolved oxygen. Ammonia is also injected for the control of pH. To find an effect of such ammonia on the copper alloy, the relations between pH and iron, and ammonia and copper are studied. Since the dependence of corrosion of iron on pH differs from that of copper, a range of pH was selected experimentally to minimize the corrosion rates of both copper and iron. Corrosion rates of various copper alloys are also compared

Cavitation erosion mechanism of titanium alloy radiation rods in aluminum melt.

Science.gov (United States)

Dong, Fang; Li, Xiaoqian; Zhang, Lihua; Ma, Liyong; Li, Ruiqing

2016-07-01

Ultrasound radiation rods play a key role in introducing ultrasonic to the grain refinement of large-size cast aluminum ingots (with diameter over 800 mm), but the severe cavitation corrosion of radiation rods limit the wide application of ultrasonic in the metallurgy field. In this paper, the cavitation erosion of Ti alloy radiation rod (TARR) in the semi-continuous direct-chill casting of 7050 Al alloy was investigated using a 20 kHz ultrasonic vibrator. The macro/micro characterization of Ti alloy was performed using an optical digital microscopy and a scanning electron microscopy, respectively. The results indicated that the cavitation erosion and the chemical reaction play different roles throughout different corrosion periods. Meanwhile, the relationship between mass-loss and time during cavitation erosion was measured and analyzed. According to the rate of mass-loss to time, the whole cavitation erosion process was divided into four individual periods and the mechanism in each period was studied accordingly. Copyright © 2015 Elsevier B.V. All rights reserved.

First principles examination of electronic structure and optical features of 4H-GaN1-xPx polytype alloys

Science.gov (United States)

Laref, A.; Hussain, Z.; Laref, S.; Yang, J. T.; Xiong, Y. C.; Luo, S. J.

2018-04-01

By using first-principles calculations, we compute the electronic band structures and typical aspects of the optical spectra of hexagonally structured GaN1-xPx alloys. Although a type III-V semiconductor, GaP commonly possesses a zinc-blende structure with an indirect band gap; as such, it may additionally form hexagonal polytypes under specific growth conditions. The electronic structures and optical properties are calculated by combining a non-nitride III-V semiconductor and a nitride III-V semiconductor, as GaP and GaN crystallizing in a 4H polytype, with the N composition ranging between x = 0-1. For all studied materials, the energy gap is found to be direct. The optical properties of the hexagonal materials may illustrate the strong polarization dependence owing to the crystalline anisotropy. This investigation for GaN1-xPx alloys is anticipated to supply paramount information for applications in the visible/ultraviolet spectral regions. At a specific concentration, x, these alloys would be exclusively appealing candidates for solar-cell applications.

Thermodynamic Properties of Alloys of Iron and Silicon

International Nuclear Information System (INIS)

Vecher, R.A.; Gejderih, V.A.; Gerasimov, Ja.I.

1966-01-01

The Fe-Si phase diagram is complex. At 1000°K there are FeSi 2 (β) and FeSi phases and solid solutions of silicon in α and α' iron. EMF measurements were made on the electrochemical cells: Fe|Fe 2+ , KI + Nal|Fe-Si at 600-800°C molten The alloys were prepared from particularly pure components by powder metallurgy and protracted annealing. Studies were made of ten alloys with silicon content between 85 and 4% in all the phase fields in the diagram section at 1000°K. We calculated the integral thermodynamic quantities ΔG, ΔH and ΔS for the formation of the silicides FeSi 2 (β), FeSi and Fe 3 Si at the mean temperature for the experimental range (1000°K), and also (using the thermal capacity of the silicides, the iron and the silicon) at 298, 1188 and 1798°K. The heats of formation of the silicides mentioned at 298°K (kcal/mole) are -19.4, -17.6 and -22.4 respectively. The data existing in the literature enable us to calculate the heat of formation of FeSi 2.33 (α-leboite) at 298°K and this is found to be -14.4 kcal/mole. The heats calculated by us are 1.5-3 kcal higher than the experimental values of Corber and Olsen. The heats of mixing calculated by us for liquid alloys agree well with data in the literature. The data obtained can be regarded as due to the change in the character of the bond in silicides from metallic to covalent when the silicon content is increased. From the data for alloy solutions of silicon in a-iron, the iron activities were calculated. It was found that the α ⇌ α' transformation observed is a real phase transformation. The two-phase range is wider than shown in the phase diagram (from data in the literature). Conversion of the iron activities in solid solution to liquid solution gives good agreement with the data of Chipman. (author) [fr

Experimental investigation of hardness of FSW and TIG joints of Aluminium alloys of AA7075 and AA6061

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Chetan Patil

2016-07-01

Full Text Available This paper reports hardness testing conducted on welded butt joints by FSW and TIG welding process on similar and dissimilar aluminium alloys. FSW joints were produced for similar alloys of AA7075T651 and dissimilar alloys of AA7075T651- AA6061T6. The Friction stir welds of AA7075 & AA6061 aluminium alloy were produced at different tool rotational speeds of 650,700, 800, 900, 1000 and transverse speed of 30, 35, 40 mm/min. TIG welding was conducted along the rolling direction of similar and dissimilar aluminium plates. The Brinell hardness testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the welds

Anodic electrochemical treatment of amorphous alloys

International Nuclear Information System (INIS)

Isaev, N.I.; Yakovlev, V.B.; Osipov, Eh.K.; Isaev, A.V.; Trofimova, E.A.; Vasil'ev, V.Yu.

1983-01-01

The aim of the investigation is to reveal peculiarities of the process of anodic oxidation and properties of anode oxide films, formed on the surface of amorphous alloys. Amorphous alloys on the base of rectifying metals of Zr-Ni, Zr-Cu-Ni, Zr-Al-Ni, Zr-Cu-Sn, Zr-Al, Zr-Mo systems are studied. Electrolytes which do not dissolve or weakly dissolve oxide film, such as boric acid electrolyte (40-45 g/l H 3 BO 3 and 18 cm 3 /l of the 25% aqueous NH 4 OH solution) and 20% H 2 SO 4 solution, are used for oxidation. Results of investigations, carried out on amorphous alloys, contaning noticeable quantities of non-rectifying components - Cu, Ni, Sn, Fe, Mo etc - have shown that non-rectifying components harden a process of anodic oxidation and decrease the current efficiency. Amorphous alloys, containing only rectifying components are oxidated in anodic way, the regularities of film growth being similar to those obtained for crystalline materials

Role of alloying additions on the properties of Cu–Al–Mn shape memory alloys

Energy Technology Data Exchange (ETDEWEB)

Dasgupta, Rupa, E-mail: rupadasgupta@ampri.res.in; Jain, Ashish Kumar; Kumar, Pravir; Hussain, Shahadat; Pandey, Abhishek

2015-01-25

Highlights: • Cu based SMAs with high transition temperature could be made using LM route. • The properties depend on alloying composition. • Property characterisation establishes feasibility of making SMAs. - Abstract: The effect of alloying seven different elements [Zn, Si, Fe, Ni, Mg, Cr and Ti] on the microstructure, hardness, phase precipitation and transformation temperature in a Cu–12.5Al–5Mn alloy with a view to possible improvements as a result of these additions is the focus of the reported study. The base alloy has been chosen keeping in mind its ability to exhibit shape memory properties and improved ductility over other Cu-based SMAs. The objective was to ascertain changes or improvements attained due to the individual tertiary additions. The samples were prepared through liquid metallurgy route using pure copper, aluminum, manganese and the respective quaternary alloying elements in right quantities to weigh 1000 g of the alloy in total and were melted together. Samples from the cast alloys were subject to homogenisation treatment at 200 °C for 2 h in a muffle furnace and furnace cooled. Samples from the homogenised alloys were heated and held for 2 h at 920 °C followed by ice quenching to obtain the desired martensitic structure for shape memory behaviour. The alloys in the cast, homogenised and quenched conditions were metallographically polished to observe the martensitic phase formation mainly in quenched samples which is a pre requisite for exhibiting shape memory properties in these alloys. X-ray Diffraction studies were carried out on the cast and quenched samples using Cu Kα target; and the phases identified indicate martensitic phase precipitation; however in some cases the precipitation is incomplete. Differential Scanning Calorimetric [DSC] studies were carried out on quenched samples from room temperature to 600 °C maintaining a constant rate of 10 °C/min. Results indicate clear transformation peaks in all the samples which

Role of alloying additions on the properties of Cu–Al–Mn shape memory alloys

International Nuclear Information System (INIS)

Dasgupta, Rupa; Jain, Ashish Kumar; Kumar, Pravir; Hussain, Shahadat; Pandey, Abhishek

2015-01-01

Highlights: • Cu based SMAs with high transition temperature could be made using LM route. • The properties depend on alloying composition. • Property characterisation establishes feasibility of making SMAs. - Abstract: The effect of alloying seven different elements [Zn, Si, Fe, Ni, Mg, Cr and Ti] on the microstructure, hardness, phase precipitation and transformation temperature in a Cu–12.5Al–5Mn alloy with a view to possible improvements as a result of these additions is the focus of the reported study. The base alloy has been chosen keeping in mind its ability to exhibit shape memory properties and improved ductility over other Cu-based SMAs. The objective was to ascertain changes or improvements attained due to the individual tertiary additions. The samples were prepared through liquid metallurgy route using pure copper, aluminum, manganese and the respective quaternary alloying elements in right quantities to weigh 1000 g of the alloy in total and were melted together. Samples from the cast alloys were subject to homogenisation treatment at 200 °C for 2 h in a muffle furnace and furnace cooled. Samples from the homogenised alloys were heated and held for 2 h at 920 °C followed by ice quenching to obtain the desired martensitic structure for shape memory behaviour. The alloys in the cast, homogenised and quenched conditions were metallographically polished to observe the martensitic phase formation mainly in quenched samples which is a pre requisite for exhibiting shape memory properties in these alloys. X-ray Diffraction studies were carried out on the cast and quenched samples using Cu Kα target; and the phases identified indicate martensitic phase precipitation; however in some cases the precipitation is incomplete. Differential Scanning Calorimetric [DSC] studies were carried out on quenched samples from room temperature to 600 °C maintaining a constant rate of 10 °C/min. Results indicate clear transformation peaks in all the samples which

Development and evaluation of a magnesium–zinc–strontium alloy for biomedical applications — Alloy processing, microstructure, mechanical properties, and biodegradation

International Nuclear Information System (INIS)

Guan, Ren-guo; Cipriano, Aaron F.; Zhao, Zhan-yong; Lock, Jaclyn; Tie, Di; Zhao, Tong; Cui, Tong; Liu, Huinan

2013-01-01

A new biodegradable magnesium–zinc–strontium (Mg–Zn–Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy processing (casting, rolling, and heat treatment), microstructures, mechanical properties, and degradation properties in simulated body fluid (SBF). Aging treatment of the ZSr41 alloy at 175 °C for 8 h improved the mechanical properties when compared to those of the as-cast alloy. Specifically, the aged ZSr41 alloy had an ultimate tensile strength of 270 MPa, Vickers hardness of 71.5 HV, and elongation at failure of 12.8%. The mechanical properties of the ZSr41 alloy were superior as compared with those of pure magnesium and met the requirements for load-bearing medical implants. Furthermore, the immersion of the ZSr41 alloy in SBF showed a degradation mode that progressed cyclically, alternating between pitting and localized corrosion. The steady-state average degradation rate of the aged ZSr41 alloy in SBF was 0.96 g/(m 2 ·hr), while the pH of SBF immersion solution increased. The corrosion current density of the ZSr41 alloy in SBF solution was 0.41 mA/mm 2 , which was much lower than 1.67 mA/mm 2 for pure Mg under the same conditions. In summary, compared to pure Mg, the mechanical properties of the new ZSr41 alloy improved while the degradation rate decreased due to the addition of Zn and Sr alloying elements and specific processing conditions. The superior mechanical properties and corrosion resistance of the new ZSr41 alloy make it a promising alloy for next-generation implant applications. - Highlights: • Developed a new biodegradable magnesium–zinc–strontium (Mg–Zn–Sr) alloy for medical implant applications • Reported Mg–Zn–Sr alloy processing and microstructure characterization • Improved mechanical properties of Mg alloy after aging treatment • Improved degradation properties of Mg alloy in simulated body fluid

Magnetoimpedance effect in Nanoperm alloys

International Nuclear Information System (INIS)

Hernando, B.; Alvarez, P.; Santos, J.D.; Gorria, P.; Sanchez, M.L.; Olivera, J.; Perez, M.J.; Prida, V.M.

2006-01-01

The influence of isothermal annealing (1 h at 600 deg. C in Ar atmosphere) on the soft magnetic properties and magnetoimpedance (MI) effect has been studied in ribbons of the following Nanoperm alloys: Fe 91 Zr 7 B 2 , Fe 88 Zr 8 B 4 , Fe 87 Zr 6 B 6 Cu 1 and Fe 8 Zr 1 B 1 . A maximum MI ratio of about 27% was measured for the nanocrystalline alloy Fe 87 Zr 6 B 6 Cu 1 at a driving frequency of 0.2 MHz. The thermal annealing led to magnetic softening for this alloy, while a hardening is observed for the Fe 8 Zr 1 B 1 alloy

Positron annihilation study of the vacancy clusters in ODS Fe-14Cr alloys

Science.gov (United States)

Domínguez-Reyes, R.; Auger, M. A.; Monge, M. A.; Pareja, R.

2017-04-01

Oxide dispersion strengthened Fe14Cr and Fe14CrWTi alloys produced by mechanical alloying and hot isostatic pressing were subjected to isochronal annealing up to 1400 °C, and the evolution and thermal stability of the vacancy-type defects were investigated by positron annihilation spectroscopy (PAS). The results were compared to those from a non-oxide dispersion strengthened Fe14Cr alloy produced by following the same powder metallurgy route. The long lifetime component of the PAS revealed the existence of tridimensional vacancy clusters, or nanovoids, in all these alloys. Two recovery stages are found in the oxide dispersion strengthened alloys irrespective of the starting conditions of the samples. The first one starting at T > 750 °C is attributed to thermal shrinkage of large vacancy clusters, or voids. A strong increase in the intensity of the long lifetime after annealing at temperatures in the 800-1050 °C range indicates the development of new vacancy clusters. These defects appear to be unstable above 1050 °C, but some of them remain at temperatures as high as 1400 °C, at least for 90 min.

Strain aging in tungsten heavy alloys

International Nuclear Information System (INIS)

Dowding, R.J.; Tauer, K.J.

1991-01-01

This paper reports on tungsten heavy alloys which are two-phase mixtures of body center cubic (BCC) tungsten surrounded by a face center cubic (FCC) matrix. The matrix is most often composed of nickel and iron in a ratio of 70:30 but, occasionally, the matrix may also contain cobalt or copper. Nickel, however, is always the primary matrix component. The tungsten heavy alloy is fabricated through powder metallurgy techniques. Elemental powders are blended, pressed to shape, and sintered. Depending upon the tungsten content, the sintering temperatures are usually in the range of 1450 degrees C to 1525 degrees C. These temperatures are high enough that, as a result, the matrix is at the liquid phase and the process is known as liquid phase sintering. At the liquid phase temperature, the matrix becomes saturated with tungsten, but this does not change the FCC character of the matrix. The sintering is usually done in a hydrogen atmosphere furnace in order to reduce the oxides on the tungsten powder surfaces and create clean, active surfaces which will enhance the adherence between the tungsten and the matrix. The hydrogen atmosphere also creates the presence of excess dissolved hydrogen in the alloy. It has been shown that the hydrogen degrades the toughness and ductility of the heavy alloy. A post-sintering vacuum heat treatment is generally required to insure that there is no residual hydrogen present. The as-sintered tensile strength of a 90% tungsten, 7% nickel, 3% iron alloy (90W) is in the range of 800 to 940 MPa and can be increased significantly by cold working, usually rolling or swaging. Swaging to reductions in area of 20% can result in tensile strengths of 1250 MPa or more. As the strength increases, the elongation, which may have been 30% or more, decreases to less than 5%

Structural, thermal and magnetic investigations on immiscible Ag–Co nanocrystalline alloy with addition of Mn

Energy Technology Data Exchange (ETDEWEB)

Mondal, B.N., E-mail: bholanath_mondal@yahoo.co.in [Department of Central Scientific Services, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chabri, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Sardar, G. [Department of Zoology, Baruipur College, South 24 Parganas 743610 (India); Nath, D.N. [Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Chattopadhyay, P.P. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

2016-08-15

50Ag–50Co (at%) and 40Ag–40Co–20Mn (at%) alloys prepared by ball milling up to 50 h and subsequent isothermal annealing at the temperature range of 350–650 °C for 1 h has been investigated systematically. Mn promotes early formation of the nanostructures and solid solutions of the alloys by ball milling. In contrast, annealing at 350 °C of Ag–Co alloy resulted the dissolution of hcp Co. Annealing above 350 °C decomposes the metastable Ag–Co alloy into the polycrystalline and segregated Ag and fcc Co. Enthalpy of mixing of both the alloy has increased with increase in milling time. Both the nanocrystalline alloys prepared by ball milling and annealing have been revealed the ferromagnetic behavior. The most significant improvement of magnetic properties is yielded in as-milled Ag–Co–Mn alloy obtained after annealing at 550 °C for 1 h. - Highlights: • A complete solid solution of Ag–Co–Mn alloy obtained after 50 h of milling. • A complete solid solution of milled Ag–Co alloy forms annealed at 350 {sup °}C for 1 h. • Precipitation of fcc Co are observed after annealing above 350 °C. • Enthalpy of mixing of the alloys increased with increase in milling time. • The superior magnetic properties achieved of Ag–Co–Mn alloy annealed at 550 °C.

Spectrographic determination of niobium in uranium - niobium alloys

International Nuclear Information System (INIS)

Charbel, M.Y.; Lordello, A.R.

1984-01-01

A method for the spectrographic determination of niobium in uranium-niobium alloys in the concentration range 1-10% has been developed. The metallic sample is converted to oxide by calcination in a muffle furnace at 800 0 C for two hours. The standards are prepared synthetically by dry-mixing. One part of the sample or standard is added to nineteen parts of graphite powder and the mixture is excited in a DC arc. Hafnium has been used as internal standard. The precision of the method is + - 4.8%. (Author) [pt

Characterization and corrosion behaviour of CoNi alloys obtained by mechanical alloying

International Nuclear Information System (INIS)