International Nuclear Information System (INIS)

Concentration profiles of passive films formed on electrolytically anodized niobium and niobium-base alloys are obtained by Auger Electron Spectroscopy with simultaneous ion beam etching. The alloys investigated include 5Zr-Nb, 3Zr-10Ti-Nb, 2.5Zr-2W-Nb, and 1Zr-5Mo-5V-Nb. Experiments demonstrate that AES is among the most fascinating techniques for solving various characterization problems related to the structure and composition of the thin films formed by anodization. Data presented supports evidence that combined anodic and cathodic movements take place during film growth. 11 figures.

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Papers are presented on the development of oxidation- and sulfidation-resistant ferritic alloys; the microstructural stability of sulfidation-resistant FeCrAl stainless steels around 500 C; age hardening in Fe-Mn-Al-C austenitic alloys; the oxidation/corrosion behavior of low-Cr Fe-Cr-Ni alloys containing Zr or Nb; the high temperature oxidation/corrosion of iron-based superalloys; and the role of Mo in the Na/sub 2/SO/sub 4/ induced corrosion of superalloys at high temperature. Topics discussed include the effect of variations of Co content on the cyclic oxidation resistance of selected Ni-base superalloys; high temperature oxidation of Fe based alloys; the morphological development of high temperature oxide scales of Fe-Mn-Al base alloys; and the oxidation of an Fe-Mn-Al-C ...

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In this work, the ability of a number of Zr-containing intermetallic compounds with the Zr{sub 2}Me stoichiometry, including Zr{sub 2}Fe, Zr{sub 2}Ni, Zr{sub 2}Co and Zr{sub 4}Fe{sub 2}O{sub 0.6}, to participate in the Hydrogenation-Disproportionation-Desorption-Recombination process was investigated, revealing for the first time that the HDDR route can be employed successfully for all these compounds. 24 refs.

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Evaluation of grain boundary composition and structure in superplastically deformed AA5083-based alloys (Al-4.5Mg-1.6Mn-0.2Zr) was carried out in a field-emission gun transmission electron microscope (FEG-TEM). During superplastic deformation at high homologous temperatures materials undergo extensive grain boundary sliding (GBS) which creates a flow of defects in the near-boundary region. Recent literature has shown that the grain-boundary composition in Al-Mg alloys is not necessarily the same as the matrix, and that these differences can have an effect on GBS.

International Nuclear Information System (INIS)

The physical, chemical and mechanical properties of magnesium alloys make them attractive materials for automotive and aerospace applications. However, these materials are susceptible to corrosion and wear. This work discusses the potential of using sol-gel based coatings consisting of ZrO_2 and 15 wt.% of CeO_2. The CeO_2 component provides enhanced corrosion protection, while ZrO_2 impart corrosion as well as wear resistance. Coating deposition was performed by the dip coating technique on two magnesium alloy substrates with different surface finishes: AZ91D (as-casted, sand-blasted, and machined) and AZ31 (rolled and machined). All as-deposited coatings (xerogel coatings) were then subjected to 10 h annealing: a temperature of 180 C was applied to the AZ91D alloy and 140 C to the AZ31 alloy. Morphological and structural properties of the ...

International Nuclear Information System (INIS)

Substantial roles of precipitates such as Zr-Fe-Cr type intermetallic compounds on uniform corrosion and hydrogen pickup of zirconium alloys in pure water autoclave tests were investigated from an electrochemical point of view. In the previous paper, corrosion mechanism was elucidated by the anodic protection-precipitates degradation model. This paper describes the roles on hydrogen pickup. 633 K pure water autoclave test was performed on high purity zirconium, Zr-0.2Fe, Zr-0.2Cr, and Zr-0.1Fe-0.1Cr alloys. Hydrogen analysis after the corrosion test showed that hydrogen pickup ratio of Zr-0.2Fe alloy was about 80%. It was much higher than about 30% of pure Zr and about 10% of both Zr-0.2Cr and Zr-0.1Fe-0.1Cr alloys. Larger hydrogen ...

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Hydrogen storage alloy composites La{sub 0.7}Mg{sub 0.25}Zr{sub 0.05}(Ni{sub 0.85}Co{sub 0.15}){sub 3.5}(x=0,5,10) were prepared by ball milling method. Their structures, morphologies and the hydrogen storage characteristics were intensively studied in the present work. It was found that the bulk of composites maintained the hexagonal C14 Laves phase structure after ball milling with additional La-Mg-based alloy for two hours. Scanning electron microscopy (SEM) observations revealed that the average size of Ti{sub 0.9}Zr{sub 0.2}Mn{sub 1.5}Cr{sub 0.3}V{sub 0.3} and La{sub 0.7}Mg{sub 0.25}Zr{sub 0.05}(Ni{sub 0.85}Co{sub 0.15}){sub 3.5} particles were reduced to several hundred nanometers after ball milling process. Energy dispersive X-ray spectrometer (EDS) patterns of the composites showed that the La{sub 0.7}Mg{sub 0.25}Zr{sub 0.05}(Ni{sub ...

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The deuterium uptake behavior of Zr-2.5Nb pressure tubes in Wolsung Unit 1 was analyzed in terms of longitudinal location, operation time, and coolant temperature. The results were compared with those obtained from Canadian CANDU reactors. The amount of deuterium uptake was higher at the outlet part than at the inlet part and was also higher when subjected to a longer operation time and a higher coolant temperature. The hydrogen uptake of Zr-2.5Nb in a hydrogen gas atmosphere was dependent on the microstructure of the alloy. The aged Zr-2.5Nb consisting of {alpha}-Zr and {beta}-Zr phases. The hydrogen in the alloy decreased the rate of oxidation. This could be explained in terms of the cathodic controlled reaction of Zr-2.5Nb oxidation. (author)

International Nuclear Information System (INIS)

By means of the light microscopy and by the measurement of the mechanical properties one investigated into the phase composition and the properties of Al-Mg-Ce and Al-Mg-Y system alloys. One plotted the isothermal cross sections of the mentioned systems under 430 and 275 deg C temperatures at up to 16% magnesium concentration and up to 0.7% yttrium concentration. One determined the yield limit and strength, the relative elongation of Al-Mg base hardened and deformed alloys containing 7.0-9.9% Mg and Ce, Y, Mn, Zr dopes upon ageing under 175, 200, 250 and 300 deg C temperatures within the ageing time ensuring the hardening maximum effect

International Nuclear Information System (INIS)

In order to substitute expensive cast titanium alloys by powder ones the possibility of introduction of powder additions by mechanical stock mixing is studied. It is shown that microstructure of powder alloys of Ti-Zr(1-9%) system is typical for one-phase cast #alpha#-alloys. The Ti-Mo(1-9%) and Ti-Nb(1-9%) system alloys have microstructure typical for two-phase (#alpha#+#beta#)-alloys. For homogeneous structure to be obtained the high temprature annealing is advisable after hot pressing. Alloying with Mo, Zr and Nb permits to increase considerable the strength of powder titanium products (at 9% Mo more than two times).

International Nuclear Information System (INIS)

Substantial roles of precipitates such as Zr-Fe-Cr type intermetallic compounds on uniform corrosion and hydrogen pickup of zirconium alloys in pure water autoclave tests were investigated from an electrochemical point of view. This paper describes the roles on corrosion. A corrosion test on precipitate-containing and precipitate-free materials made from pure zirconium and a small quantity of iron and chromium, rest potential measurements on an intermetallic compound of Zr(FeCr)_2 and zirconium matrix, and a galvanic coupling test of those were performed. Results showed that corrosion behavior of zirconium alloys could be attributed to the electrochemical properties of intermetallic compounds precipitated in each alloy. Namely, the cathodic and anodic polarization characteristics were associated with anodic protection provided by the precipitates on the alloys ...

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... kov (Ukraine) INIS-UA--158 488 p. MATERIALS SCIENCE annealing creep

Energy Technology Data Exchange (ETDEWEB)

Advances in nuclear reactor technology and the use of gas-cooled fast reactors require the development of new materials that can operate at the higher temperatures expected in these systems. These include refractory alloys base on Nb, Zr, Ta, Mo, W, and Re; ceramics and composites such as those based on silicon carbide (SiCf-SiC); carbon-carbon composites; and advanced coatings. Besides the ability to handle higher expected temperatures, effective heat transfer between reactor componets is necessary for improved efficiency. Improving thermal conductivity of the materials used in nuclear fuels and other temperature critical components can lower the center-line fuel temperature and thereby enhance durability and reduce the risk of premature failure.

Science.gov (United States)

The effect of solution treatment temperature and oxygen content on the microstructure and age hardening response of the metastable beta alloy Ti-11.5Mo-6Zr-4.5Sn have been studied. Kinetics of formation of the equilibrium alpha-phase and the metastable om...

International Nuclear Information System (INIS)

The authors present an investigation of structural changes occurring in bilayer stacks with crystalline columnar growth when one of the layers is substituted by layers known to grow amorphous. In Co/Cu multilayers the Co layers were substituted by CoZr layers of varying Zr content and layer thickness. Structural characterization was performed by transmission electron microscopy (TEM). They show that the amorphization of the CoZr layers leading to a destruction of the columnar growth depends both on the Zr content and on the thickness of the CoZr layers. Additionally a change to textured growth with a normal to the substrate occurs with increasing Zr content. They explain their observations by a simple picture based on the hard sphere model.

International Nuclear Information System (INIS)

In this paper a study is made of the structure and mechanical properties of the #beta# alloy system Ti-Mo-Zr-Sn (the composition of which is equivalent to the #beta# III alloy used abroad) containing different amounts of carbon. Study of the #beta#-titanium alloy containing 0.1% C revealed the presence of particles of titanium carbide. Separation of the titanium carbide promotes a reduction in impact strength, an increased tendency toward cold shortness, and poorer workability. (author).

British Library Electronic Table of Contents (United Kingdom)

The transformation mechanism of hexagonal delta phase from the disordered bcc gamma phase has not been reported before in the Zr-rich U-Zr alloy system. With the help of X-ray diffraction, transmission electron microscopy (TEM) and high-resolution TEM analyses it was shown that the gamma to delta conversion takes place by the lattice collapse mechanism of omega transformation. It was also ascertained that a higher aging temperature or time promotes the growth of all four variants of the delta phase within a parent gamma grain. In addition, ab initio electronic structure calculations showed that the bcc to hexagonal transformation, involving partial ordering of the parent bcc phase followed by (111) plane collapse, is energetically favorable.

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The Neutral Beam Test Facility (NBTF) to be realized in Padoa will test the Neutral Beam Injection (NBI), one of the Heating and Current Drive Systems foreseen for ITER. The NBI is based on the acceleration of hydrogen or deuterium negative ions up to 1 MeV. This work has been aimed at assessing the tritium release from the NBTF in order to provide data for the safety analysis. In particular, the diffusion of the tritium through the neutral beam target material (the CuCrZr alloy calorimeter panels) has been assessed by using literature data of the diffusion coefficient. The tritium generated inside the calorimeter panels moves into both the vacuum and water side: the tritium diffusion flux has been evaluated during the beam-on (200 deg. C) and the beam-off (20 deg. C) phases of the NBTF experiments consisting of an interim campaign and a final test. The penetration depth of the tritium through the 2 mm thick ...

International Nuclear Information System (INIS)

4.82 wt% AIN and 2.98 wt% Y_2O_3 were added to Si_3N_4 as sintering agents in order to have #alpha#_Sialon composition of x=0.15 and monoclinic ZrO_2 between 0 to 10 wt% was admixed with Si_3N_4 based ceramics were fabricated by hot-pressing at 1,750 deg C for 90 min under 30 MPa in argon and nitrogen atmospheres effects of sintering atmospheres and addition of ZrO_2 on mechanical properties of Si_3N_4 based ceramics were investigated. As ZrO_2 content increased, the fraction of #alpha#-Sialon tended to decrease and the amount of cubic ZrO_2 increased because Y_2O_3 acted as the stabilizer of ZrO_2. The sintering atmospheres didn't affect on the sintering behavior and the product phases in hot-pressing of Si_3N_4. Bending strength increased when ZrO_2 content. ZrO_2 didn't contribute to the increase ...

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(Dec 1970). United States Feeney, JA Boeing Co., Renton, Wash.

British Library Electronic Table of Contents (United Kingdom)

Zirconium and particularly Zr-2.5wt%Nb (Zr2.5Nb) alloy are useful for engineering bearing applications because they can be oxidized in air to form a hard surface ceramic. Oxidized zirconium (OxZr) due to its abrasion resistant ceramic surface and biocompatible substrate alloy has been used as a bearing surface in total joint arthroplasty for several years. OxZr is characterized by hard zirconium oxide (oxide) formed on Zr2.5Nb using one step thermal oxidation carried out in air. Because the oxide is only at the surface, the bulk material behaves like a metal, with high toughness. The oxide, furthermore, exhibits high adhesion to the substrate because of an oxygen-rich diffusion hardened zone (DHZ) interposing between the oxide and the substrate. In this study, we demonstrate a two step pro...

International Nuclear Information System (INIS)

Phase transformations occuring during cold deformation in hardened #alpha#+#beta# titanium alloy of the Ti-Al-Mo-Zr-Sn-Si system with 10% summary content of alloying elements are studied by X-ray diffraction analysis. Two stages of trapsformation of metastable #alpha#''-phase are found. A conclusiop is made that ability of the alloy containing #alpha#''-phase to cold deformation is determined by the presence of favourable texture, by high degree of metastability and by volume portion of #alpha#''-phase in the alloy structure.

International Nuclear Information System (INIS)

Alloying elements such as Fe and Cr are generally considered to be effective even in small quantities for corrosion resistance of Zircaloy-4. The maximum total solubility of Fe + Cr in a Zr-Sn matrix has been reported to be very low. Therefore, most of these elements are observed in the form of ternary Zr-Fe-Cr-type precipitates. To clarify the effects of precipitates on corrosion property, Zr-1.3 Sn-(Fe,Cr) alloys containing Fe + Cr from 45 up to 180 ppm (the Fe to Cr ratio is about 2) were melted from pure zirconium (X-bar Zr and EB-Zr) and pure alloying elements. They were subjected to corrosion testing in 633 K water and microstructural analysis. It was found that precipitate-free materials showed much larger weight gains than precipitate-containing materials even at the same alloy compositions. ...

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In order to overcome the inherent disadvantages of Ti-V-based hydrogen storage alloys, such as poor activation behavior and low high-rate dischargeability, the novel composites Ti{sub 0.17}Zr{sub 0.08}V{sub 0.35}Cr{sub 0.1}Ni{sub 0.3}-x wt.% La{sub 0.7}Mg{sub 0.3}Ni{sub 2.75}Co{sub 0.75} (x = 0, 5, 10 and 20) were successfully synthesized by ball milling method in the present study. And the structure and overall electrochemical properties of as-prepared composites are investigated systemically. The electrochemical studies show that the maximum discharge capacity of the composite electrodes displays no variation with the increase of La{sub 0.7}Mg{sub 0.3}Ni{sub 2.75}Co{sub 0.75} content, whereas the high-rate dischargeability (HRD) and the activation behavior are distinctly improved with increasing x. The electrochemical hydrogen kinetics of composite electrodes is also studied by means of electrochemical impedance ...

International Nuclear Information System (INIS)

A one-nanometer scale transmission electron microscope electron probe X-ray microanalysis characterization of as-deposited and annealed aluminum--11.5 at.% zirconium multilayer samples in cross-section synthesized by magnetron sputtering is reported on here. Composition line profiles were acquired across Zr layers in as-deposited material and samples isochronally annealed in a differential scanning calorimeter to temperatures of 290 C and 485 C. A spatial resolution of approximately 1.5 to 2.0 nm was achieved in these experiments and will be improved by deconvolution of the instrumental electron probe function from the data. The as-deposited structure consisted of crystalline Al and Zr layers with thin amorphous layers at the Al/Zr interfaces. The amorphous interface layers increased in thickness upon annealing to 290 C. Additionally, at 290 C a metastable cubic alloy forms at the ...

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The ball-milling method was used to produce Mg-50 wt.% ZrFe{sub 1.4}Cr{sub 0.6} composite. The thermodynamic, kinetic, and cycling properties, as well as the resistance to oxidation were examined. This composite possesses excellent kinetic properties, even at moderate temperature. Scanning electron microscopy, energy-dispersive spectrum, transmission electron microscopy and X-ray diffraction were used to characterize the composite before and after hydriding. The fine ZrFe{sub 1.4}Cr{sub 0.6} particles covering Mg particles acting as a ''catalytic film'', a significant amount of imperfections and some alloy powder in the Mg matrix introduced by ball milling all contributed to the enhanced absorption/desorption rate. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Total hemispherical emittance was measured for the SP-100 reactor fuel cladding alloy (Nb-l% Zr). Based on a standard test method (ASTM C 835-82), experiments were conducted on a reference sample of oxidized stainless steel and then on a sample of actual cladding. The sample is heated in a vacuum by passing DC current through it until reaching equilibrium. Measurements are made of the electrical power dissipated in the sample and of the surface temperature. Using the Stefan-Boltzmann Law and some key assumptions concerning conductive and radiative heat transfer, the measured quantities are used to calculate emittance. Calculated values for unoxidized cladding range from 0.159 +/- 5.35% at 913 K to 0.200 +/- 4.51% at 1091 K. Highest value measured after onset of visible oxidation was 0.339 +/- 3.92% at 1269 K.... SP-100, Reactor, Emittance, Niobium, Fuel cladding, Emissivity.

International Nuclear Information System (INIS)

The corrosion resistance of zircaloy is affected by conditions of heat treatment in the manufacturing steps to be formed into a final product as a structural material. In the manufacturing method of the present invention, a Zr alloy controlled to contain Sn: 0.8 to 1.2wt%, Fe: 0.17 to 0.28wt%, Cr: 0.05 to 0.15wt%, Ni: 0.04 to 0.10wt%, Nb: 0.01 to 0.09wt%, oxygen: 1,000 to 1,500ppm and Si, an Si impurity at a concentration of 120ppm or less and balance of Zr is melted into a cast piece, to which #beta# hardening is applied. Then, rolling and annealing treatment are applied so that the total heat input amount to the material: #SIGMA#Ai ranges from 1 x 10"-"1"9 to 1 x 10"-"1"7. With such procedures, a Zr alloy structural material for a reactor core having excellent homogeneous corrosion resistance and hydrogen absorption resistance for a long period of time while having a sufficient ...

International Nuclear Information System (INIS)

Zirconia has demonstrated a very moderate toughening effect in nitrogen-based ceramic composites because the reaction between tetragonal zirconia (t-ZrO_2) and nitrogen results in additional zirconia stabilization to a nontransformable t' or cubic structure. In O'-SiAlON matrices, the oxygen concentration increases and the oxygen-rich intergranular glassy phase prevents zirconia from nitridation. As a result, tetragonal ZrO_2 is maintained and is transformable in the O'-SiAlON materials. The present study has provided transmission electron microscopy (TEM) evidence of the zirconia transformation and the associated toughening effect in a ZrO_2/O'-SiAlON composite. The implications and limitations of the transformation on toughening of the material are discussed.

Science.gov (United States)

This paper reports Palladium alloy compositions investigated for suitability as a nonreactive material for the processing of ceramic superconductors. Barium-based superconductors were tested on Pd-Au and Pd-Ag alloys for reactivity. Bismuth-based superconductors were tested on a Pd-Ag alloy. The least reactive was found to be 70% Pd-30% Ag for the barium-based high-temperature superconductors (HTSC), whereas 30% Pd-70% Ag was found to be least reactive for bismuth-based HTSC.

Energy Technology Data Exchange (ETDEWEB)

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.% C and 0.07 at.% Y. 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, ...

International Nuclear Information System (INIS)

An Al-5%Mg-0.18%Mn-0.2%Sc-0.08%Zr-0.002%Be was subjected to equal-channel angular extrusion up to true strains of #approx#3 and #approx#8, that resulted in the formation of partially recrystallized and fully recrystallized structure, respectively. It was shown that the alloy with partially recrystallized structure exhibits highest strength and ductility. The material with fully recrystallized structure showed lowest fatigue crack growth rate and highest value of fracture toughness. Reasons of this unusual effect of microstructure on crack propagation resistance under fatigue are discussed.

International Nuclear Information System (INIS)

Beta C trademark, a metastable beta titanium alloy developed by RMI Titanium Company, continues to be used in new applications due to its excellent mechanical properties and resistance to corrosion. New data in this paper include mechanical properties in large sections, cold drawn bar and welds. Fatigue crack growth and corrosion data are added to supplement previously published data.

International Nuclear Information System (INIS)

The possibility of the group preconcentration of Zr(4), Hf(4), Nb(5), and Ta(5) countercurrent liquid chromatography using extraction systems based on di-2-ethylhexylphosphoric acid N-benzoyl-N-phenylhydroxylamine, and tetraoctylethylenediamine (TOEDA) is studied. A method have been proposed for the group extraction of Zr(4), Hf(4), Nb(5), and Ta(5) from solution of geological samples. At the stage of the preconcentration of Zr(40, Hf(4), Nb(5) and Ta(5) with a 0.1 M solution of TOEDA in chloroform from mixture of oxalic (0.01 M) and hydrochloric (0.1 M) acids, matrix components are eluted with a flow of the mobile phase, Then, upon changing the eluent (2.0 M HCl), the four elements mentioned above are extracted to a small (7-8 mL) eluate fraction. The results of determining Zr, Hf, Nb, and Ta by inductively coupled plasma atomic emission spectrometry in the international standard ...

International Nuclear Information System (INIS)

Nonevaporable getters (NEGs) have been extensively studied in the last several years for their sorption properties toward many gases. In particular, an innovative alloy as a thin film by magnetron sputtering was developed and characterized at the European Organization for Nuclear Research. It is composed of Ti-Zr-V and protected by an overlayer of palladium (Pd), according to a technology for which the authors got the licence. NEG-Pd thin films used in combination with ion getter pumps is a simple, easy way to handle pumping devices for ultrahigh and extremely high vacuum applications. To show how to apply this coating technology to the internal surface of different types of ion pumps, the authors carried out several tests on pumps of various shapes, sizes (in terms of nominal pumping speed), and types (diode, noble diode, and triode). Special care was taken during the thermal cycle of baking and activation of the pumps to preserve the internal ...

Energy Technology Data Exchange (ETDEWEB)

Based on recent thermodynamic estimations on the CeO{sub 2}-CeO{sub 1.5}, CeO{sub 2}-2ZrO{sub 2} and CeO{sub 1.5}-ZrO{sub 2} systems, isothermal sections of the ternary CeO{sub 2}-ZrO{sub 2}-CeO{sub 1.5} system are calculated in the 1300-1700 C region. Additionally, the complex relation between the nonstoichiometry, y, in CeO{sub 2-y}, the composition of the CeO{sub 2}-ZrO{sub 2} solid solution and the oxygen partial pressure (PO{sub 2}) for different ZrO{sub 2} containing solid solutions Ce{sub z}Zr{sub 1-z}O{sub 2-x} (with z=0.2, 0.5, 0.8) are evaluated from 600 to 900 C. The relation between the degree of Ce{sup +4} to Ce{sup +3} reduction under different PO{sub 2} in the fluorite CeO{sub 2-y} and Ce{sub z}Zr{sub 1-z}O{sub 2-x} solid solutions at different temperatures can be used as a guide in the development of ...

International Nuclear Information System (INIS)

The beta transformation characteristics and mechanical properties of the #beta# titanium alloy Ti_5_0Zr_3_0Nb_1_0Ta_1_0 in the temperature range between 200 and 900 deg. C have been studied by means of X-ray diffraction (XRD), Vickers hardness (HV), and tensile test techniques. In the as-rolled state, only #beta#-phase was identified by XRD. Upon heat-treating at 250 deg. C for 4 h, the #alpha#-phase was precipitated from the #beta#-phase matrix, and leading to an increase of Vickers hardness. A maximum HV value was observed at 400 deg. C, and then HV value decreased with increasing heat-treating temperature. Above 650 deg. C, HV value remained almost constant. During heat-treating at 300-650 deg. C, the decomposition of the metastable #beta#-phase has been found to proceed through a phase separation reaction leading to the formation of #beta#-Ti and #beta#-Zr b.c.c. solid solution phases rather than the formation of solute ...

International Nuclear Information System (INIS)

The #beta#-CEZ alloy : Ti-5%Al-2%Sn-4%Zr-4%Mo-2%Cr-1%Fe is a near #beta# titanium alloy. Since its processing routes include heat treatment (consisting of solution treatment and ageing), it has been decided to study the influence of the #beta# phase stability on #alpha# phase precipitation and hardening kinetics. Small sized specimens, coming from industrial heats, have been heat treated above and below the #beta# transus, and then water quenched. Therefore, several degree of #beta# stability are obtained. When it is increased (i.e. the solution treatment temperature is lowered), #alpha# or #omega# phases precipitations are delayed, as well as the hardening phenomena. Moreover, the #omega# stability domain is reduced. The mechanisms of #alpha# or #omega# precipitation are discussed, and related to the hardening kinetics. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Welded Ni-base alloys and Alloy 800 were exposed under metal dusting conditions at 600 C and 650 C for up to 6000 hours. Alloy 800 was attacked very strongly already in the first days and Alloy 600 also rather soon and widespread, on both materials attack started mainly in the heat affected zone. Several surface states of Alloy 600: brushed, ground, sand-blasted and pickled were tried only grinding caused a modest delay and decrease of metal dusting attack. Generally the attack was less widespread but deeper at 650 C than at 600 C, also for Alloy 601 and 602. The latter alloys show minor, mainly local attack, but especially the welds are affected. TIG welding led to better resistance than hand-welding. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

International Nuclear Information System (INIS)

A study of the #pi#1g/sub 9/2/ orbit size in "8"8Sr, "9"0Zr, and "9"2Mo is presented. The rms radius for the point-proton density is extracted by studying transitions to 8"+ states in these nuclei. The radii are consistently larger than a value determined in a magnetic electron scattering experiment on "9"3Nb. A qualitative discussion of the ground state occupation of the #pi#1g/sub 9/2/ orbit based on the transition amplitudes to the 8"+ states is given.

International Nuclear Information System (INIS)

... Toshiba Corporation, Isogo Engineering Center, Yokohama, Kanagawa (Japan)

British Library Electronic Table of Contents (United Kingdom)

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr2N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr...

Energy Technology Data Exchange (ETDEWEB)

General corrosion behavior of ALLOY 800 in high temperature water was studied in relation to its surface film structure. The surface film formed in water was found to decrease the corrosion rate of ALLOY 800. This film is composed of Ni ferrite, and can be obtained by oxidation in air or steam. Based on these results, air or steam oxidation treatment to inhibit Ni and Co release of ALLOY 800 into high temperature water is proposed. (author).

International Nuclear Information System (INIS)

Beta-C trademark is a metastable beta titanium alloy which can be heat treated to achieve a good combination of properties such as tensile strength, fatigue strength, ductility and toughness, such as needed in aircraft fasteners. Variations in hot and cold processing parameters and solution heat treatment can affect the resultant grain structure which in turn affects subsequent aging response and mechanical properties. Several processing/heat treating routes on round bar are explored in this study to determine the effects on microstructure and various mechanical properties.

International Nuclear Information System (INIS)

The fatigue life variability of the #alpha#+#beta# titanium alloy, Ti-6Al-2Sn-4Zr-6Mo increased with decreasing stress level. The variability in life was found to be due to segregation of lives due to two failure mechanisms. A bimodal cumulative distribution model was shown to accurately describe the combined failure modes. The nominal failure processes for the two regimes were similar, with crack nucleation occurring in equiaxed #alpha#p particles, irrespective of life or stress level. However the variability in life was not controlled by the size of the crack-nucleating #alpha#p, but rather by the ability of the material to distribute deformation and avoid early crack nucleation.

International Nuclear Information System (INIS)

Laser surface modification can lead to formation of a novel microstructure on the surface of a material resulting in improved surface properties. During the past one and half decades, a number of investigations have been reported on laser surface modification techniques for improving the corrosion resistance of various materials. This paper reviews various work reported on utilising laser modification techniques for enhancing the aqueous corrosion resistance of materials. The laser surface modification work carried out on materials like stainless steels, C-steels, low alloy steels and non-ferrous materials such as Zr, Zn, Al, Ni, Mg and their alloys has been covered in the review. General features observed in improving the corrosion resistance after laser processing have been discussed and scope for future investigations in this field has been highlighted. (author). 97 refs., 15 figs., 5 tabs.

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the role of amorphous SiO{sub 2} particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO{sub 2} was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of {gamma}-phase and amorphous nano-SiO{sub 2} particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO{sub 2} particles were uniformly distributed in the ...

International Nuclear Information System (INIS)

To achieve sufficient thermodynamic efficiency, space nuclear power systems must operate above 1000"0C. A quantitative evaluation of the existing mechanical properties data for the refractory alloys relevant to space nuclear power systems design lifetimes up to seven years at temperatures up to 1400"0C is being conducted. The most important properties for space nuclear power systems are long-term high-temperature (>1000"0C) creep strength and ductility, low-temperature (<400"0C) fracture toughness [including ductile-to-brittle transition temperature, (DBTT)], and ductility at high strain rates; of special concern are the above properties for weldments of refractory alloys, composition, applied stress, test temperature, test environment (e.g., vacuum, lithium), and thermomechanical treatment (TMT) history. Currently being evaluated are, in order of ascending mp, selected alloys of niobium (e.g., Nb-1% ...

International Nuclear Information System (INIS)

Zirconium-base alloys are used primarily as fuel cladding material and other core structure material in water cooled nuclear power reactors. Main research achievements and problems about corrosion of zirconium alloys are reviewed; the present theories and challenge are summarized. In the 1980s, great progress had been made towards correlating alloy composition, microstructure and irradiation with corrosion resistance. In the 1990s, main researches are focused on exploring actual mechanism of corrosion, optimizing both alloy composition and microstructure in order to minimize the fuel cycle costs through burnup optimization.

International Nuclear Information System (INIS)

A new high strength titanium alloy has been developed primarily intended for fastener applications. While Ti-6Al-4V is used extensively as a fastener alloy in the aerospace industry, its shear strength allowable is limited to 655 MPa (95 ksi). For higher shear strength requirements, various steels or nickel-based alloys are used (up to 860 MPa (125 ksi)), but with the attendant density penalty. This new alloy is intended to provide the 860 MPa shear strength at roughly a 40% weight savings. After screening various alloy systems, the optimum chemistry has been selected as follows: Ti-6.0V-6.2Mo-5.7Fe-3Al. In light of its 125 ksi shear strength goal, the alloy has been designated TIMETAL reg-sign 125.

Energy Technology Data Exchange (ETDEWEB)

In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic sensors based on the technique of surface plasmon resonance. The metals considered for this analysis are silver, gold, copper and aluminium. The performance of the sensor with different bimetallic nanoparticle alloy combinations is evaluated and compared numerically. The performance is analysed in terms of three parameters: sensitivity, signal-to-noise ratio (SNR) and operating range for the sensing layer refractive index values. On the basis of the comparison and some logistic criteria, the best possible bimetallic alloy combinations along with a requisite alloy composition ratio are predicted. The bimetallic nanoparticle alloy combination is capable of simultaneously providing larger values of sensitivity, SNR and operating range, ...

International Nuclear Information System (INIS)

The present invention provides a fuel cladding tube having an excellent corrosion resistance and thus a long life, and a suitable manufacturing method therefor. Namely, in the fuel cladding tube, the outer circumference of an inner layer made of a zirconium base alloy is coated with an outer layer made of a metal more corrosion resistant than the zirconium base alloy. Ti or a titanium alloy is suitable for the corrosion resistant metal. In addition, the outer layer can be coated by a method such as vapor deposition or plating, not limited to joining of the inner layer material and the outer layer material. Specifically, a composite material having an inner layer made of a zirconium alloy coated by the outer material made of a titanium alloy is applied with hot fabrication at a temperature within a range of from 500 to 850degC and at a ...

International Nuclear Information System (INIS)

Technology of plasma sputtering, structure and properties of zirconium dioxide coatings were studied. Necessity of void number increase to enhance coating heat-resistance is shown. Optimal powder particle size (20-60 #mu#m) providing optimal coating porosity was determined. Weight part of stabilizating oxide (Y_2O_3) in ZrO_2 for formation in coating of microcracks serving as barriers for macro-cracks propagation was determined.

International Nuclear Information System (INIS)

We present a study of the crystal field in PrNiAl, NdNiAl, ErNiAl and ErCuAl intermetallic compounds based on inelastic neutron spectroscopy. These compounds crystallize in the ZrNiAl-type hexagonal structure with an orthorhombic symmetry on rare-earth sites. The results are compared with the specific-heat data, and the lower parts of the crystal-field energy-level schemes are determined. (orig.)

Energy Technology Data Exchange (ETDEWEB)

A new method of determining the nuclear level density is presented. This method is based on the statistical analysis of the partial width fluctuations appearing in an excitation function of the radiative proton capture. The method was applied in the case of the /sup 88/Sr(p,..gamma..sub(..omega..))/sup 89/Y and /sup 89/Y(p,..gamma..sub(..omega..))/sup 90/Zr reactions. The density of levels with spin I/sup -/ in /sup 90/Zr and the densities of levels with spins 1/2/sup +/ and 3/2/sup +/ in /sup 89/Y at excitation energies from 10.9 to 11.6 MeV and from 9.3 to 10.8 MeV respectively, were determined with an uncertainty of about 35%.

Energy Technology Data Exchange (ETDEWEB)

Results are presented from studies on the quality of cast parts made by counterpressure casting of high-strength aluminum alloy AMKh-605, and Al-Cu-Mn-Cr alloys (5.6-6.4% Cu, 0.25-0.55% Mn, 0.20-0.55% Cr, 0.20-0.45% Ti, 0.08-0.25% Zr, less than or equal to0.25% Fe, less than or equal to0.25% Si, less than or equal to0.05% Mg). Chill castings were heat treated by quenching from 450/sup 0/C (20 hours) in water, aging at 160/sup 0/C for five hours with cooling in air. Fractograms of tensile specimens are presented. Scanning electron microscopy allows an ambiguous determination of the cause of failure of a part, be it at initial crystallization crack defects or burns, and also allows a relationship to be established between structure and mechanical properties.

International Nuclear Information System (INIS)

Fatigue-crack growth in air and in aqueous 3.5-percent NaCl as well as fracture toughness are evaluated for the metastable beta-titanium alloy Ti-3Al-8V-6Cr-4Mo-4Zr in various microstructural conditions. Two solution heat treatments (SHT), 800 C and 927 C, were chosen to produce two different grain sizes. Approximately 20 vol pct unrecrystallized beta grains remained after SHT at the lower temperature. Yield stresses were 895 and 850 MPa, respectively. Both simplex and duplex aging treatments were performed for both grain sizes to vary the distribution of alpha precipitates while keeping the yield stress in the range of 1075-1220 MPa for all aged conditions. Unaged material exhibits significantly higher fracture toughness levels than aged material. The unrecrystallized regions were associated with a loss in ductility and toughness. 21 refs.

Energy Technology Data Exchange (ETDEWEB)

Results of an experimental study of the interaction of 140 MeV alpha particles with /sup 90/Zr nuclei resulting in fragmentation of the alpha particle are reported. The experimental observations of the study are analyzed and are found to show that alpha particle breakup reactions leading to at least 4-body final states, composed of two charged alpha particle fragments, contribute significantly to the singles yield of charged fragments observed at a fixed forward angle. The conclusions are based on coincidence measurements where one charged fragment is detected at a small forward angle which remains fixed, while the second charged fragment is detected at a series of coplanar secondary angles. The largest coincidence charged particle yield for the multiparticle final state events results from /sup 90/Zr(..cap alpha..,pp)X reactions, where both of the measured protons have energy distributions similar to the proton singles ...

International Nuclear Information System (INIS)

The optimum of strontium amount for good modification of AK7, AK9, AK11, AK52, AK104 alloys was determined on the base of the analysis of microstructural changes. The stability of the modifier was investigated on the way of successive remelting of billets. The influence of amount of modifier on the impact strength of the alloys was established. (author)

International Nuclear Information System (INIS)

Modern commercial alloys are not suited for future steam turbines of operating temperatures beyond 700 C. #gamma#'-hardened alloys like Waspaloy have good mechanical characteristics but have defects when large batches are melted. #gamma#'/#gamma#''-hardened alloys like Inconel 706, on the other hand, are easy to produce but have insufficient microstructural long-term stability and insufficient creep strength. Mixed crystal solidified alloys like Inconel 617 have excessive yield stress at forging temperatures. Two new alloys were therefore developed. Results so far show that they have good production characteristics but insufficient mechanical characteristics. The reasons for this are currently under investigation. (orig.)

International Nuclear Information System (INIS)

Recent advances made in the area of amorphous and nanocrystalline alloys exhibiting high saturation inductions are reviewed. A new chemical composition was identified that achieves a saturation induction of 1.64 T in an iron-based amorphous alloy. This alloy, when used in electrical transformers, shows a much improved performance over the existing amorphous alloy. Nanocrystalline FeCoCuNbSiB alloys are found to have saturation induction levels reaching 1.7 T. These materials are suited for use in sensors and inductors carrying large currents. Some of these nanocrystalline alloys show a BH squareness ratio exceeding 90%, which can be utilized in pulse power devices. Recent developments in the applications of these materials are also pointed out.

International Nuclear Information System (INIS)

... Sergio Department of Materials, University of Oxford, Oxford (United Kingdom)

Energy Technology Data Exchange (ETDEWEB)

In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic temperature sensing based on the technique of surface plasmon resonance (SPR). The metals considered for the present analysis are silver, gold and aluminium. The analysis is derived mainly from the thermo-optic effect along with some fundamental concepts of metal optics such as surface scattering, phonon-electron scattering and electron-electron scattering. The performance of the sensor with three different bimetallic nanoparticle alloy combinations is evaluated and compared, numerically, in terms of its sensitivity and accuracy. On the basis of the comparison and some logistic criterion, we predict the best possible bimetallic alloy combination along with a requisite alloy composition ratio that simultaneously provides higher values of both sensitivity ...

Energy Technology Data Exchange (ETDEWEB)

We propose a dissolution-passivation model to account for the electrochemical behavior of Alloy 800 and 316L stainless steel under steam generators operating conditions. This model is similar to the one defined for nickel, considering the known importance of this element on the studied alloys. The comparison of the rates of the elementary steps points out the favorable influence of dissolved oxygen and phosphate ions on the dissolution of Alloy 800, even in the presence of chloride ions. The sensitivity of 316L SS is greater, especially because of the lowest stability of oxide-like intermediate.

British Library Electronic Table of Contents (United Kingdom)

Abstract Purpose: Long-term success of metal ceramic restorations depends on metal ceramic bond strength. The purpose of this study was to determine whether recasting of base-metal alloys has any effect on metal ceramic bond strength. Materials and Methods: Super Cast and Verabond base-metal alloys were used to cast 260 wax patterns. The alloy specimens were equally divided into five groups and cast as: group A 0.0%, B 25%, C 50%, D 75%, and E 100% once-cast alloy. Each group was divided into two subgroups: the first group was cast with Super Cast and the second with Verabond. In each subgroup half of the cast alloys were veneered with Vita VMK 68 and the others with Ceramco 3. Results: Recasting decreased bond strength (p < 0.006) when used for 50% once-cast alloy. Group E with 100% new S...

Energy Technology Data Exchange (ETDEWEB)

In response to European operating experience regarding Alloy 800 steam generator (SG) tube cracking, New Brunswick Power Nuclear (NBPN) recognized two important shortcomings in the industry SG technical support framework. First, information exchange networks between utilities with Alloy 800 SG tubing should be strengthened. Second and more importantly, there is a need for consistent industry guidance for Alloy 800 SG tubing degradation management, supported by clear technical bases. It is NBPN's perspective that this guidance can be improved immediately using the extensive amount of laboratory and field data that is available for Alloys 600, 690, and 800, and EPRI methodology developed to predict the performance of Alloy 690. NBPN has initiated the development of a performance-based inspection plan. This effort is ...

Energy Technology Data Exchange (ETDEWEB)

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/sup 0/C and 90/sup 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/sup 0/C, Ti and Ti-Pd show very high passivation ...

Science.gov (United States)

Development of a shear and leach complex for UO/sub 2/-SS clad fuel was continued with major emphasis on the operation of a rotary drum leacher. Flooding data for nozzle plate pulse columns at high A/O ratios are reported. Engineering tests of dissolution of Zr--6% U alloy with HF in molten salt demonstrated a dissolution rate of 0.8 to 1.5 mg/cm/sup 2//min. Subsequent fluorination with 100% F/sub 2/ proceeded at half times of 40 to 135 min. The results of a high level waste calcination (run R-72) made with formaldehyde treated simulated Purex waste are reported. (auth)

Energy Technology Data Exchange (ETDEWEB)

The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol-water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05 M or fluoride <0.05 M containing 30% ethylene glycol solution, they are more corrosive than the blank (30% ethylene glycol-70% water). However, at concentrations <0.05 for chloride or >0.05 M for fluoride ...

International Nuclear Information System (INIS)

An alloy of composition Ti-4.4 wt.% Ta-1.9 wt.% Nb is being developed as a structural material for corrosion applications, as titanium and its alloys possess excellent corrosion resistance in many oxidizing media. The primary physical metallurgy database for the Ti-4.4 wt.% Ta-1.9 wt.% Nb alloy is being presented for the first time. Determination of the #beta# transus, M_s temperature and classification of the alloy have been carried out, employing a variety of microscopy techniques, X-ray diffraction (XRD), micro-hardness and differential scanning calorimetry (DSC). The #beta# transition temperature or #beta# transus determined using different experimental techniques was found to agree very well with evaluations based on empirical calculations. Based on chemistry and observed room temperature microstructure, the alloy has been classified as ...

British Library Electronic Table of Contents (United Kingdom)

A microanalytical characterization of cast magnesium alloys of eutectic origin based on the Mg?Al?Ca ternary matrix system has been carried out in order to investigate the influence of alloying elements on their microstructure as well as microchemistry-processing-microstructural relations using structure-sensitive techniques of electron microscopy, mechanical spectroscopy (internal friction), X-ray diffractometry, and advanced microanalytical methods including electron probe compositional analysis. Following the data obtained here there is direct correlation of microstructure with creep properties of the new experimental magnesium alloys. The creep and heat-induced properties of the multicomponent magnesium alloys containing low range of inexpensive additions of titanium (0.07?0.2%) or str...

International Nuclear Information System (INIS)

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 ...

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Metal dusting corrosion has been a serious problem in the petroleum and petrochemical industries, such as reforming and syngas production systems. This form of deterioration has led to worldwide material loss for 50 years. For the past three years, we have studied the mechanism of metal dusting for Fe- and Ni-base alloys. In this report, we present a correlation between the weight loss and depth of pits that form in Ni-base alloys. Nickel-base alloys were also tested at 1 and 14.8 atm (210 psi), in a high carbon activity environment. Higher system pressure was found to accelerate corrosion in most Ni-base alloys. To reduce testing time, a pre-pitting method was developed. Mechanical scratches on the alloy surface led to fast metal dusting corrosion. We have also developed preliminary data on the ...

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This patent describes an energy storage device. It comprises: a working electrode, a counter electrode, electrically isolated from the working electrode; an electrolyte in contact with the working electrode and the counter electrode, and means for collecting electrical current therefrom; the working electrode consisting essentially of an amorphous metal alloy of the formula: A{sub {ital a}}M{sub {ital b}}M{prime}{sub {ital c}}, wherein A is at least one metal selected from the group consisting of Ag, Hg and Pt; M is at least one metal selected from the group consisting of Pb, Cu, Cr, Mo, W, Ni, Al, Co, Fe, Zn, Ru, Cd and Mn; M{prime} is at lest one of the elements selected from the group consisting of Ca, Mg, Ti, Zr, Hf, V, Nb and Ta; and wherein a ranges from about 0.005 to about 0.80; b ranges from 0.05 to about 0.70; and c ranges from about 0.08 to about 0.95.

Energy Technology Data Exchange (ETDEWEB)

Alloy 800 has been used for steam generator (SG) tubing for more than 30 years, primarily in CANDU reactors worldwide and in reactors in Germany. Extensive laboratory testing and in-service experience suggest that the Alloy 800 tubing has excellent resistance to corrosion-related degradation under appropriate operating conditions. In planning refurbishment of nuclear plants stations, a key concern is the longevity of existing SGs up to the 60-year lifetime of the refurbished plant. The paper reviews an existing methodology based on the concept of the improvement factor, and refines its estimation based on data specific to CANDU operating conditions. The paper presents a more advanced Bayesian probabilistic approach to estimate the degradation free lifetime distribution of Alloy 800 tubing, which is used to quantify the probability of degradation during the service life and to ...

Science.gov (United States)

Ni-free shape memory alloys are promising functional materials for medical applications. A newly developed Ti-Mo based shape memory alloy shows superelasticity after thermomechanical treatment. However, the microstructure evolution and precipitation during thermomechanical processes are still not well understood. In the present paper, compressive deformation behavior at a series of temperatures of 298K - 973K and tensile deformation behavior of the alloy after aged at 573K - 973K have been investigated systematically. It is found that the compressive yield stress and ultimate compressive strength change with the deformation temperature. The ultimate tensile strength and yield stress of aged specimens also change with the aging temperature following a non-linear relationship. Microstructures of aged specimens as well as effects of lattice softening and aging-induced precipitates on the deformation ...

International Nuclear Information System (INIS)

In equipment industries, the equipments handling industrial water and pure water are numerous. In power generation including nuclear power generation, water serves as a working medium. Review is made on the experiences in the corrosion of iron and nickel base alloys in high temperature, high pressure water and the results of researches derived from them. Under high temperature and high pressure, carbon steel, low alloy steel, stainless steel and high nickel alloy cause corrosion even in pure water. But in the case of serious corrosion, chlorine, oxygen, alkali and others in water take part. The following matters are described: corrosion by steam; stress corrosion cracking in pure water; corrosion by impurities in high temperature, high pressure pure water, i.e. chlorine ions, dissolved oxygen, and alkali; corrosion under radiation. (J.P.N.).

International Nuclear Information System (INIS)

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 ...

International Nuclear Information System (INIS)

Alloy 800 has been used for steam generator (SG) tubing for more than 30 years, primarily in CANDU reactors and in reactors in Germany. Extensive laboratory testing and in-service experience suggest that the Alloy 800 tubing has excellent resistance to corrosion-related degradation under specified and appropriate operating conditions. In planning refurbishment of CANDU stations, a key concern is the longevity of existing SGs up to the 60 year lifetime of the refurbished plant. The paper reviews an existing methodology based on the concept of the improvement factor, and estimates it based on experimental data specific to CANDU operating conditions. The paper presents a more advanced probabilistic approach to estimate the degradation free lifetime distribution of Alloy 800 tubing, which is used to quantify the probability of degradation during the service life and to evaluate the ...

Energy Technology Data Exchange (ETDEWEB)

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr{sub 2}N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective ...

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The oxidative dehydrogenation (ODH) of light alkanes is an alternative way for the production of olefins. A wide variety of catalytic systems has been investigated. Vanadium oxide based catalysts were described in the literature as effective catalysts for the ODH of propane. The catalytic activity and selectivity depend on the kind of support material, the kind of dopants and the formation of complex metal oxide phases. In recent papers it was claimed that both orthovanadate and/or pyrovanadate species are selective for the ODH of propane. Niobia based materials were investigated as catalysts for acidic and selective oxidation type reactions. In the ODH of propane niobia exhibited a high selectivity to propene but the conversion of propane was low. V{sub 2}O{sub 5}-Nb{sub 2}O{sub 5} catalysts proved to be catalytically active and selective and showed no formation of oxygenates. In the present study the influence of the niobia dopant of the ...

International Nuclear Information System (INIS)

The weldability and high temperature strength properties of tungsten-inert-gas (TIG) weldments of Hastelloy alloy XR were investigated by using two different heats of filler metals; the first (HXRF1) was designed on the basis of multiple regression analysis; the second (HXRF2) was the reference material. Bend tests, the FISCO cracking test and optical metallography were used to evaluate weldability. Tensile and creep tests were performed at 900deg C to evaluate high temperature strength properties. The results of weldability tests for both alloys showed good performance. The tensile properties of the weldments were remarkably improved in particular with respect to high temperature ductility. The creep rupture strength in the weldments made with alloy-designed HXRF1 was much higher than those of the Hastelloy alloy XR-II base metal with a higher B content. Furthermore, the creep ...

Science.gov (United States)

Intermetallic compounds are regarded as highly promising for applications as high temperature structural materials. However, recent studies have demonstrated that a number of ordered alloys exhibit environmental embrittlement when tested in various environments at ambient temperature. When exposed to hydrogen gas or electrolytically charged with hydrogen, a significant ductility loss has been reported. The reaction of water vapor with reactive elements in the crack tip results in the generation of atomic hydrogen which diffuses from the surface to the interior and causes embrittlement. In this paper, the authors try to analyze the sensitivity of hydrogen embrittlement of ordered alloys based upon energetical considerations.

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The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base ...

Energy Technology Data Exchange (ETDEWEB)

Recently the increase of steam temperature and pressure of power plant is required to enhance the thermal efficiency and reduce the CO{sub 2} emission. For the application to advanced USC (Ultra Super Critical) boiler with steam temperature around 700 C, the application of Ni-based alloy such as Alloy617 will be necessary. A new Ni-based alloy USC141 (20Cr-10Mo-2Ti-Al-bal.Ni) with excellent creep rupture strength and low thermal expansion has been developed by Hitachi Ltd. and Hitachi Metals Ltd. as the candidate material for 700 C USC turbine components. In present work, to investigate the possibility for boiler tube application of USC141, its weldability and high temperature strength properties were experimentally examined. The tested material as solution-treated condition shows higher creep rupture strength than that of Alloy617. GTAW (Gas Tungsten Arc ...

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Nitridation of Cr-bearing alloys can yield low interfacial contact resistance (ICR), electrically- conductive and corrosion-resistant CrN or Cr2N base surfaces of interest for a range of electrochemical devices, including fuel cells, batteries, and sensors. This paper presents results of exploratory studies of the nitridation of two high Cr (30-35 wt%) commercially available Ni-Cr alloys and a ferritic high Cr (29 wt.%) stainless steel for proton exchange membrane fuel cell (PEMFC) bipolar plates. A high degree of corrosion resistance in sulfuric acid solutions designed to simulate bipolar plate conditions and low ICR values were achieved via nitridation. Oxygen impurities in the nitriding environment were observed to play a significant role in the nitrided surface structures that formed, with detrimental effects for the Ni-Cr base alloys, but beneficial effects for the stainless ...

Energy Technology Data Exchange (ETDEWEB)

The study of passive films formed on a nickel base alloy type Inconel 600 is performed by capacitance measurements (Mott-Schottky approach). This research is supported by the passivation study of the alloying elements Ni, Cr, Fe and high purity alloys Ni-Cr, Ni-Fe, Ni-Cr-Fe. The results obtained show that the capacitive behaviour of the Inconel 600 in the passive state is similar to that on a p-n heterojunction to which a barrier zone of nickel oxide is added. The individual or combined action of alloying elements on the development of this kind of electronic structure is discussed. (authors). 5 refs., 6 figs.

Science.gov (United States)

The TTT diagrams describing the beta to alpha isothermal transformation have been made by isothermal dilatometry for pure uranium and 21 alloys based on chromium, silicon, molybdenum, iron, aluminium, zirconium. The thermal cycle preceeding the isothermal...

International Nuclear Information System (INIS)

VT6 titanium alloy long-range fibers have been extracted from the suspended melt drop with the following high-rate solidification. Formation of the structure of fibrous porous material prepared from these fibers has been studied. 7 refs.; 5 figs.; 2 tabs.

British Library Electronic Table of Contents (United Kingdom)

The review provides a general idea about the types of metallic alloys and the pure metals used as implant materials in dental and orthopedic surgery. Their corrosive behavior in both real solutions and various media that model human biological fluids is described. Based on the literature data, it is concluded that multicomponent alloys containing titanium, niobium, zirconium, tungsten, molybdenum, aluminum, and silicon are the most resistant to corrosion. Implants made of different types of stainless steel are preferred when manufacturing orthopedic devices for short-term use.

International Nuclear Information System (INIS)

1 - Description or function: Continuous energy cross-section data library for the Monte Carlo program MCNP based on the JEF-2.2 evaluated nuclear data library (ACE Format). Format: ACE Number of groups: Continuous energy Nuclides (107): H-1, H-2, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-nat, N-14, N-15, O-16, O-17, F-19, Na-23, Mg-nat, Al-27, Si-nat, Cl-nat, Ti-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Zr-90, Zr-91, Zr-92, Zr-94, Zr-96, Zr-nat, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-100, Mo-nat, Tc-99, Ru-101, Ru-102, Ru-104, Rh-103, Pd-105, Pd-107, Ag-109, I-129, Xe-131, Cs-133, Pr-141, Nd-143, Nd-145, Pm-147, Sm-147, Sm-149, Sm-150, Sm-151, Sm-152, Eu-153, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Pb-nat, ...

International Nuclear Information System (INIS)

Magnesium alloys have been increasingly used in automotive and electronic industries because of their excellent strength to weight ratio and EMI shielding properties. However, magnesium alloys have low formability at room temperature due to their unique mechanical behavior (twinning and untwining), prompting for forming at an elevated temperature. In this study, a temperature dependent constitutive model for magnesium alloy (AZ31B) sheet is developed. A hardening law based on non linear kinematic hardening model is used to consider Bauschinger effect properly. Material parameters are determined from a series of uni-axial cyclic experiments (T-C-T or C-T-C) with the temperature ranging 150-250 deg. C. The influence of temperature on the constitutive equation is introduced by the material parameters assumed to be functions of temperature. Fitting process of the assumed model to measured data is presented ...

International Nuclear Information System (INIS)

Strain embrittlement in Ti base alloys during tensile testing was investigated. Results show that in an #alpha#-#beta# titanium alloy the local activity of H in alpha phase (#alpha#/sub H//sup #alpha#) increases and activity of H in beta phase (#alpha#/sub H//sup #beta#) decreases as the equiaxed #alpha# particle size decreases at constant volume fraction of phases. Thus with decreasing particle size there would be a tendency for H to move from #alpha# to #beta#, decreasing the H content of #alpha#. Also whether H tended to move from #beta# to #alpha# or from #alpha# interiors to the #alpha#-#beta# interface this tendency would be reduced by surface tension effects, making the alloy less susceptible to embrittlement.

Energy Technology Data Exchange (ETDEWEB)

The program introduced here for determining and describing the multi-axial creep of pipes is based, on the one hand, on the results of the nuclear process heat prototype plant material program and, on the other hand, on the possible load conditions which arise for evaluating accidents or extreme working situations. The basis of a theoretical description of multi-axial creep is the invariant theory in which both the von Mises configuration change hypothesis and the Norton creep law are included. Combined tension and torsion are also considered in detail, the superimposition of cyclic stresses in the tensile threshold area is discussed and cases of partial relaxation are explained. Experimental results for the discussed loads are introduced, which have led to satisfactory agreement between theory and experiment. (orig./MM).

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The phase transformations and properties of a precipitation-hardened Ni-Cr-based alloy are investigated as a function of C, B, Nb, and Cr contents. It is found that the primary role of Nb consists in the formation of an independent phase, delta-Ni3Nb, a part of a gamma/gamma-prime-delta eutectoid (for high C and B concentrations) and in stimulating the gamma-sigma reaction consecutively with the gamma double prime-delta reaction (for low C and B concentrations). In both cases, the long-term strength characteristics of the Nb-alloyed system are relatively low. The substitution of boron for carbon contributes to a reduction in the number of nucleation sites for topologically close-packed phases and to the formation of more stable (with respect to excess compounds) M3B2 and MB2 borides. The high-boron material exhibits better properties and phase stability under mechanical and thermal loading. 13 references.

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The chemical composition and the semiconducting properties of passive films formed on nickel based alloy (Alloy 600) in acidic sulphate solution, pH 2.0 at room temperature were studied using Auger analysis, voltammetric techniques and the Mott-Schottky approach. The results obtained revealed that the presence of both chromium and mixed nickel-iron oxides in the films leads to the development of a p-n heterojunction, which controls their electronic structure, similarly manner to the case of stainless steels and Alloy 600 in borate buffer solution. This behavior has been interpreted as representing of an oxide system, which has a duplex character, with an inner p-type semiconducting region, mainly formed by chromium oxide and an outer n-type semiconducting region, containing iron oxide. It could also be observed that the nickel oxide present in the films acts as a barrier layer conferring improved ...

International Nuclear Information System (INIS)

Generally, neutron, ion and electron Irradiations cause a substantial amount of hardening and significantly alter the deformation behavior of metals and alloys at relatively low irradiation temperatures. A radiation hardening is caused by the formation of microstructural defects such as dislocation loops, voids and precipitates under irradiation. Therefore, it is important to have a better knowledge of the irradiation induced microstructural defects under irradiation condition. As a part of the National mid- and long-term atomic energy R and D program, we are dealing with the radiation hardening behavior in Fe-Cr binary alloy. Fe-Cr binary alloy is a base alloy of Ferritic/Martensitic steel(F/M steel) planning to use for the Gen IV nuclear system. In this work, we investigated the radiation hardening and microstructural defect evolution in ion irradiated Fe-Cr ...

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The present paper describes the development of ultra-fine grains on the surface of AZ31 alloys caused by hydrogenation and dehydrogenation treatment, so-called HDDR process. Upon hydrogenation process, disproportionation reaction occurred in forming of MgH{sub 2}, Mg{sub 0.42}Al{sub 0.58}, and Al phases. In the following desorption process, the three phases were re-solved into the AZ31 alloy. As a result of the HDDR phenomena, the grain size of AZ31 alloy powders was reduced down to about 100 nm after the heat treatment at 350 C under a hydrogen pressure of 7 MPa for 24 h. The grain size tended to be increased with increasing process temperatures. In addition, the HDDR process was also applied to AZ31 alloy plates. By the HDDR process at 450 C, the grain size was reduced to less than 500 nm, where hydrogenated layer thickness was limited to be in the range of about 20 {mu}m from the surface. The Vickers ...

International Nuclear Information System (INIS)

Application of Alloy 800 in steam generator tubing of fast reactors, where continuous service temperature of the order of 550"0C is experienced, has been analyzed with respect to small variations in its chemical composition. Several laboratory melts of Alloy 800 have been prepared and their microstructural and mechanical property changes during simple aging and creep tests at 500 to 600"0C have been studied. It has been found that in the above temperature range precipitation of M_2_3C_6 on the grain boundaries is independent of the Ti : C ratio generally specified for Alloy 800. Gamma prime precipitation occurred in alloys containing as low as 0.5 percent Ti + Al after 1000 h of aging and was accompanied with a creep ductility decline. Upon #gamma# precipitation creep rate was retarded and its reacceleration for test times up to 8500 h at 550"0C was not observed. Based on the ...

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Dissimilar metal welds between ferritic low-alloy and austenitic stainless steels commonly occur in power plant application. In order to overcome some of the problems encountered here, a trimetallic configuration using an intermediate piece (such as Alloy 800) between the austenitic and ferritic steels has been suggested. This paper describes some features of the joints between modified 9Cr-1Mo steel and Alloy 800, produced with Inconel 82/182 filler material. The joints require heat-treatment after welding and the results have shown that a treatment at 760 C for 2 h would be optimal. Although most tensile failures occurred in the weld metal the welds were found to exhibit strength properties that are at least equal to those of Alloy 800, with a tensile elongation lying between those of the two base materials. Similarly, while the weld metals are slightly less tough than the two ...

International Nuclear Information System (INIS)

Repassivation resulting from the bared metal surface is a critical process for judging whether or not material suffers from corroding or immunizing. Nickel based alloys with high chromium content were developed to increase the corrosion resistant to sulphur compounds. Active humps resulting from active dissolution of nickel were obtained by creating the bared metal surfaces in thiosulphate solutions. The lower the Cr content the higher is the dissolution rate. The passive films formed on the bared metal surface were examined by ac impedance. Results suggest the formation of multi-layers oxide which were affected by active dissolution reactions during repassivation. (author).

International Nuclear Information System (INIS)

This paper reviews the state of the art of silicon-germanium technology and assesses the problems of building thermoelectric modules in Europe, based upon silicon-germanium alloys, for use in multihundred watt radio-isotope thermoelectric generator. The generator developed in the United States for the International Solar Polar mission has been used as a reference system. The essential features of an alternative system, which employs thermocouples fabricated from improved silicon-germanium alloys based upon a design by the Fairchild Space and Electronics Company, is also described. It is concluded that although the fabrication of reliable electrical contacts will present a major problem, the technology is available in Europe to build thermoelectric modules similar to those developed for the International Solar Polar mission. (orig.).

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Some N-containing or S-containing organic substances and some acetylenic alcohols were tested as inhibitors of the corrosive attack suffered by Fe-based metallic glasses in deaerated 0.1 N sulfuric acid (H{sub 2}SO{sub 4}) solution at 25 C. It was verified that the specific action these compounds exerted on the corrosion process of the amorphous alloys was similar to the one these compounds exerted on polycrystalline iron. The most efficient substances were those containing a sulfur atom with available lone pairs, which chiefly inhibited the anodic reaction of both metal specimens. Owing to the chemical and physical homogeneity of the amorphous alloy, the chemisorbed inhibitor film that formed on the glassy surface was more stable and protective than that formed on the polycrystalline iron.

British Library Electronic Table of Contents (United Kingdom)

In the present paper, the effects of hydroxyapatite (HA) content on the microstructure, thermal and mechanical properties of Ti-based glassy alloy/HA composite prepared by spark plasma sintering (SPS) are investigated. The microstructure of the composites is homogeneous when the HA is lower than 2 wt%. When the HA content is higher than 3 wt%, the crystalline precipitates with size of less than 5 nm are distributed in the glassy matrix. HA decomposes during sintering procedure for the composite with high HA content. With increasing HA addition, compressive strength decreases. Especially for the HA content is over 2 wt%, the strength decreases sharply because of partial crystallization of glassy alloy matrix.

International Nuclear Information System (INIS)

The elastic scattering angular distributions of 25 MeV alpha particles scattered from "7"3Ge, "8"9Y, "9"0Zr, "9"1Zr"9"4Zr, "9"3Nb, "4"4Ca and "4"5Sc have been measured experimentally, and fitted using a conventional optical model. (author).

International Nuclear Information System (INIS)

... 3 reactions mev range 10-100 neutron spectra neutrons nuclear reaction

International Nuclear Information System (INIS)

A distinguishing design feature of CANDU nuclear reactors is the use of horizontal fuel channels housed in a horizontal vessel called a calandria, which is made of stainless steel 304L. Each channel consists of a Zr-2.5%Nb alloy pressure tube and an externally concentric Zr-2 calandria tube. The calandria tubes are joined to the end plates (tubesheets) of the calandria vessel by joints formed by roller expansion. The bores in the tubesheets are grooved. Roller expanded joints provide a cost effective means of joining dissimilar materials, require minimal space and no maintenance. The quality of these roller expanded joints is important from a sealing, strength and stress corrosion point of view. The roller expansion process consists of expanding the calandria tubes to deform them plastically against the bores and into the grooves of the tubesheets. Therefore, understanding the effect of the number, geometry and the pitch of ...

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This paper reports that high-dielectric ceramics with the composition (94.7% {minus} x) (Ba,Sr)TiO{sub 3} + PbZrO{sub 3} + 5Bi{sub 2}Ti{sub 3}O{sub 9} + 0.3MnO{sub 2}, where the ration (Ba)/(Sr) = 1.25 and x {le} 15 mol%, have been developed for high-voltage capacitors. The dielectric constant of the ceramics is in the range 1200 to 1900 at room temperature, and the room-temperature dielectric loss, tan{delta}, is less than 0.3%, except when 15 mol% PbZrO{sub 3} is added with sintering at 1180{degrees}C to 1240{degrees}C for 2 h. Ceramics with more than 8 mol% zirconate show the Y5S characteristic of capacitance, and those with less than 8 mol% additive exhibit the Z5S characteristic. The dielectric constant gradually increases with increment in the ac signal voltage at 60 Hz, but decreases beyond a threshold value that varies with zirconate content and sintering conditions. The variation of the dielectric constant at 2 kVrms/mm (with respect ...

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We describe the growth, fabrication, and characterization of an ultraviolet (UV) photoconductive detector based on In{sub x}Al{sub y}Ga{sub 1-x-y}N quaternary alloy that is lattice matched to GaN. The detector consisted of 0.1 {mu}m In{sub x}Al{sub y}Ga{sub 1-x-y}N alloy grown on 0.5-1.0 {mu}m GaN epilayer by metalorganic chemical vapor deposition. With varying indium concentration, the cut-off wavelength of the In{sub x}Al{sub y}Ga{sub 1-x-y}N detectors could be varied to the deep UV range. The most important and intriguing result is that the responsivity of the In{sub x}Al{sub y}Ga{sub 1-x-y}N quaternary alloy exceeded that of AlGaN alloy of a comparable cutoff wavelength by a factor of five. This makes the nitride quaternary alloy very important material for solar blind UV detectors applications particularly in the deep UV range where Al rich AlGaN ...

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A heat resistant nickel base alloy which is excellent in not only hot and cold workability but also high temperature strength properties and which also possesses satisfactory oxidation resistance. The nickel base alloy consists essentially of 0.001-0.15 percent carbon, 0.0005-0.05 percent calcium, 20.0-126.0 percent chromium, 4.7-9.4 percent cobalt, 5.0-16.0 percent molybdenum, 0.5-4.0 percent tungsten, with the total of molybdenum plus tungsten being from 9.0 to 16.5 percent, and the balance nickel and inevitable impurities. The alloy may further contain one selected from the group consisting of (1) 0.3-1.5 percent aluminum and 0.1-1.0 percent titanium, (2) 0.001-0.30 percent at least one of yttrium and rare earth elements, and (3) 0.001-1.0 percent at least one of niobium, vanadium and tantalum, whereby the aforementioned characteristics are further enhanced.

Science.gov (United States)

The authors develop a procedure for the determination of the Al, Ti, V, Cu, Mn, Mo, and W content of nickel-base alloys by neutron activation analysis. An M-10 microtron with a beryllium target in a paraffin microtron (with a beryllium target) in a paraffin moderator served as the neutron source. In order to evaluate the procedure for quantitative analysis, the authors determined the contents of the above elements in five reference standards, the bulk density of which was 2.94-4.17 g/cm/sup 3/. The difference in the self-absorption of the gammaquanta was assessed by determining the number of gamma-quanta with energies in the range 60-1332 keV that had passed through the RS N4 and N8 which showed the greatest difference in their composition. The results of the determination are presented. The proposed procedure is simple and rapid and can be used to determine the alloying components of nickel-based ...

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Transition joints in power plants between ferritic steels and austenitic stainless steels suffer from a mismatch in coefficients of thermal expansion (CTE) and the migration of carbon during service from the ferritic to the austenitic steel. To overcome these, nickel-based consumables are commonly used. The use of a trimetallic combination with an insert piece of intermediate CTE provides for a more effective lowering of thermal stresses. The current work envisages a trimetallic joint involving modified 9Cr-1Mo steel and 316LN austenitic stainless steel as the base materials and Alloy 800 as the intermediate piece. Of the two joints involved, this paper describes the choice of welding consumables for the joint between Alloy 800 and 316LN. Four consumables were examined: 316, 16-8-2, Inconel 82 and Inconel 182. The comparative evaluation was based on hot cracking tests and estimation ...

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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 ...

Science.gov (United States)

Superconductivity of binary alloys spanning the A-15 compounds V/sub 3/Si, V/sub 3/Ge, V/sub 3/Ga, and V/sub 3/Al and the pseudobinary derivatives of these stoichiometric compounds was surveyed by studying samples prepared by rf-sputtering from alloy cathodes. The possible formation of the hypothetical A-15 binaries ''V/sub 3/P,'' ''V/sub 3/B,'' and ''V/sub 3/C'' and their pseudobinary formation with V/sub 3/Si was also explored. Efforts to form these hypothetical alloys were not successful. The T/sub c/'s were measured resistively and the structure and lattice constants were determined by x-ray analysis. A maximum T/sub c/ of 11.7/sup 0/K was obtained for A-15 V/sub 3/Al, and the importance of a suitable deposition temperature and high sputtering pressures was examined. It is proposed that large variations ...

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Metallic components within or immediately adjacent to gasifiers, such as gas distributors, thermowells, transfer lines, and cyclones, are subjected to severe of temperature, pressure, and hostile multicomponent gas environments. Metallic heat exchangers/waste-heat boilers resistant to sulfidation, corrosion. and erosion in low- and medium-Btu gas environments are essential components in large-scale gasification schemes, in both dry ash and slogging type gasifiers. Components, in general. must be resistant to corrosion, erosion, and high-temperature creep. A substantial data base is needed on the mechanical properties of materials exposed to complex gas environments to provide a more viable basis for establishing long-term reliability of components. This work examines high-temperature creep of Alloy 800, a high-chromium alloy widely used in coal conversion systems, after exposure to oxygen and oxygen/sulfur mixed-gas ...

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In order to understand the anodic behaviour of Al--Mo and Al--W amorphous alloys in the borate buffer electrolyte, samples of these alloys were polarized galvanostatically. The resultant anodic films were thicker than the passive films formed during potentiodynamic polarization enabling detailed examination of the films and alloy substrates by surface analytical methods. AES investigations suggest that the anodic films formed at low and moderate voltages on Al--Mo or Al--W amorphous alloys consist of Al-oxide, whereas refractory metals remain unoxidized and enriched at the film/substrate interface. Molybdenum and tungsten act as 'dissolution moderators', restraining the substrate dissolution process at the film/substrate interface. However, after anodization at high voltages (50 V), AES revealed the presence of an oxidized refractory metal in the inner part of the anodic film. ...

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For evaporation crystallization of extremely corrosive FGD scrubber solutions which - depending on the process - can lead all the way to a product suitable for depositing, an economic equipment concept based on metallic construction materials was to be investigated. In a parameter study, electrochemical test methods were used to determine the influence of the pH value, the Fe{sup 3+}, F and So{sub 2} contents in a solution containing 200 g/l CaCl{sub 2}+30 g/l NaCl at 80deg C on the resistance to pitting corrosion of stainless steels and NiCrMo alloys. In addition, electrochemical and wet corrosion tests (e.g. crevice corrosion) were conducted using original FGD scrubber solutions with 43-50% dry substance from the power plants Reuter-West, Oberhavel and Rudow of the BEWAG, Berlin. The results were compared to those of standardized and non-standardized short-term tests for determining the critical pitting corrosion and crevice corrosion ...

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The aims of the present work were to investigate possible compatibility between sodium zirconium phosphate (NZP) and Synroc titanate phases, to prepare NZP-based waste forms by hot-pressing rather than sintering, and to investigate the incorporation in NZP of (a) Cs/Sr as simulated heat-generating nuclides; (b) simulated actinides; and (c) simulated Purex waste. The NZP samples were prepared by methods similar to those used for Synroc. The precursor NZP phase was formed from tetrabutyl zirconate Zr(OC{sub 4}H{sub 9}){sub 4}, sodium nitrate, and 85% orthophosphoric acid. Simulated waste nitrate solutions were then mixed with the liquid precursor. After stir drying of the precursor, calcination was carried out at 700{degree}C to remove nitrates and organics.

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Alloy 690 and Alloy600 are used as a material for the steam generator tubing in the pressurized water reactor(PWR) of nuclear power plants due to its high corrosion resistance. Although those are a highly corrosion resistance material, their stress corrosion cracking(SCC) have been found on occasion, which are deeply related to a surface oxide film on a base material which have occurred on the primary side as well as the secondary side of a tubing. And The SCC is accelerated in the existing Pb which is the impurity of secondary steam generator components. The Oxide on a steel surface in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, which is formed by a growth of the oxide layer on the metal surface. The outer layer of the oxide is less adhesive, which is formed by a dissolution and precipitation mechanism. Growth processes of the inner ...

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Pt-based ternary catalysts have been proposed as electrode materials for low temperature fuel cells. Pt-Ru-based ternary catalysts were tested as anode materials with improved CO tolerance or enhanced activity for methanol or ethanol oxidation. Ternary catalysts based on platinum alloyed with first row transition metals were tested as cathode materials with improved activity for the oxygen reduction. This paper presents an overview of the preparation methods and structural characteristics of these ternary catalysts. (author)

International Nuclear Information System (INIS)

A thermodynamic analysis of the behaviour of Alloy 800 in helium based atmospheres relevant to the High Temperature Gas Cooled Reactor indicates that, depending upon the precise gas composition, oxidation and carburisation, or carburisation alone may be expected. The prime influence appears to be the moisture level. The morphology and structure of the reaction products are discussed. It is shown that the 'reactive' elements chromium, manganese, titanium and silicon are concentrated in the oxide scale which is normally duplex in structure. Aluminium oxide is formed at grain boundaries and in an internal oxidation zone together with titanium and sometimes silicon. In carburising conditions, mixed titanium-chromium carbides are formed. When this occurs, intergranular penetration is maximised. Weight gain data are assessed and briefly described and a tentative model for the mechanism of corrosion of Alloy 800 in HTR helium is ...

British Library Electronic Table of Contents (United Kingdom)

The age hardening behavior of Al-4.5%Cu alloy composite reinforced with zircon sand particulates and produced by stir casting route has been investigated in different quenching media viz, water, oil, and salt brine solution (7wt%). Optical microscopy of the as cast alloy composite indicates that the matrix of the composite has the cellular structure. Copper rich CuAl2 precipitates have been found near particle matrix interface. The results of ageing demonstrate that the microhardness of age hardenable Al-Cu based alloy composites depend on the quenching medium in which they are heat treated. Salt brine quenching is faster as compared to water and oil, even if higher strength is obtained but cannot be used for complex shapes and thin sections where oil quenching is the alternative due to mi...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Even though metal ceramic restorations (MCRs) are widely used by clinicians, the influence of the metal on the color of overlaying porcelain is unknown. Purpose The purpose of this study was to analyze the color alterations of different types of metal ceramic alloys during several stages of metal surface preparation and to determine the effect of those changes on the resulting color of opaque porcelain (OP). Material and Methods Seven different types of alloys (3 base metal, 3 noble, and 1 high noble) were used to prepare disk-shaped specimens (1 mm x 10 mm, n=3), followed by OP application (0.1 mm). Lab values of specimens were recorded after different stages of metal surface preparation (ingot, after casting, after oxidation, and after the OP application) in addition...

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Microstructure characterization is important for controlling the quality of laser welding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft and an unambiguous identification of phases in the weldment was accomplished. It was found that there are {gamma}-FeCrNiC austenite solid solution dendrites as the matrix, (Nb, Ti) C type MC carbides, fine and dispersed Ni{sub 3} Al {gamma}' phase as well as Laves particles in the interdendritic region of the seam zone. A brief discussion was given for their existence based on both kinetic and thermodynamic principles.

International Nuclear Information System (INIS)

The size distributions of precipitated Ni clusters on the surface of a LaNi_5-based alloy immersed in alkaline solution (alkaline treatment) at 383 K for 0-110 min were precisely determined by combining superparamagnetic analysis and transmission electron microscopy (TEM) observations. The superparamagnetic analysis indicated that the diameters of the Ni clusters were smaller than #approx#25 nm in all samples, while their average values increased approximately from 5 to 9 nm with increasing alkaline treatment time. The spatial distribution of the Ni clusters was successively observed by TEM, which agreed fairly well with the estimated size distribution by superparamagnetic analysis. Therefore, estimation of the actual size distribution of Ni clusters by superparamagnetic analysis was proved to be feasible. Based on the above results, a precipitation process for Ni clusters by alkaline treatment is proposed.

International Nuclear Information System (INIS)

Solid solution-strengthened nickel base alloys have been used for nuclear stream generator tubing in pressurized water reactors since the beginnings of commercial nuclear power. The purpose of this paper is to recap and update the authors understanding of the relationship between processing, resulting structure, and properties for Alloy 600 and to discuss the requirements for optimized performance in both primary and secondary environments. Potential replacement materials and their performance will be discussed. Also discussed is the role and importance of system chemistry, bulk and local, and control and its relationship to performance. A discussion of potential mechanisms of environmentally assisted failure is also discussed.

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The report covers the results of exposing materials for steam turbines to increased steam temperatures in two modules of the KOMET 650 testing facility at the Westfalen power plant. Ferritic/martensitic steels with 9 to 12% Cr and austenite and nickel-based alloys were investigated. Some experimental coatings on low-alloy Cr steel were also tested. The principal findings are presented. It will become possible to construct advanced power stations to be operated at higher temperatures. (orig.)

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The goal of this project is to provide materials engineers, chemical engineers and plant operators with a software tool that will enable them to predict localized corrosion of process equipment including fabricated components as well as base alloys. For design and revamp purposes, the software predicts the occurrence of localized corrosion as a function of environment chemistry and assists the user in selecting the optimum alloy for a given environment. For the operation of existing plants, the software enables the users to predict the remaining life of equipment and help in scheduling maintenance activities. This project combined fundamental understanding of mechanisms of corrosion with focused experimental results to predict the corrosion of advanced, base or fabricated, alloys in real-world environments encountered in the chemical industry. At the heart of this approach is the ...

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In this work a Ni-based superalloy GMR 235 was investigated. We determined convenient metallographic methods for preparation of bulk metallographic specimens, extraction carbon replicas, transparent metallic foils and minor phase extraction. In addition, the alloy microstructure was characterised using different metallographic techniques. (orig.)

International Nuclear Information System (INIS)

In this study, dissimilar welds between HP heat-resistant steel and Incoloy 800 were made with four different filler materials including: 309 stainless steel and nickel-based Inconel 82, 182 and 617. The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Grain boundaries migration in the weld metals was studied. It was found that the migration of grain boundaries in the Inconel 82 weld metal was very extensive. Precipitates of TiC and M_2_3C_6 (M = Cr and Mo) in the Inconel 617 weld metal are identified. The necessary conditions for the formation of cracks close to the fusion line of the 309-HP joints are described. Furthermore unmixed zone near the fusion line between HP steel base metal and Inconel 82 weld metal is discussed. An epitaxial growth is characterized at the fusion line of the 309-Alloy 800 and ...

International Nuclear Information System (INIS)

Focused ion beam (FIB) microscopes have become well-established in the semiconductor industry during the past decade, and are rapidly gaining attention in the field of materials science, both as a tool for producing site specific, parallel sided transmission electron microscope (TEM) specimens and as stand alone specimen preparation and imaging systems. FIB secondary electron imaging (SEI) of nickel-based alloys, such as commercially produced Alloy 600 (approximately Ni 15Cr 10Fe 0.5C), has been demonstrated to show a high degree of sensitivity to the presence of deformation in the alloy, and FIB secondary ion imaging (SII) is particularly useful for identifying the presence of grain boundary corrosion, as secondary ion yields from metallic specimens can increase by three orders of magnitude in the presence of oxygen. This 'oxygen enhanced yield', makes FIB SII ideal for detection of corrosion at grain ...

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An application of the renormalized random phase approximation to nuclear structure is presented for the semi-magic nuclei /sup 88/Sr and /sup 90/Zr. It is reported the outcome for the microscopic approach in comparison with the semiphenomenological version for the particle-hole forces.

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It is necessary to measure strength and creep behavior to guarantee the safe and reliable usage of refractory alloys at extremely high temperatures. In the literature there is very little information available about the properties of Mo-Re alloys at temperatures higher than 1000 C. A special test facility has been designed and built for stress-rupture testing at very high temperatures (up to 3000 C) of refractory metals and alloys in inert atmospheres. - The stress-rupture strength as well as the creep behavior of molybdenum-rhenium alloys with rhenium contents between 41 and 51 wt.% have been determined at temperatures ranging from 1200 to 2000 C, and rupture times of up to 10 hours using this facility. Previous measurements of stress-rupture strength and creep behavior of pure rhenium have been compared with the measurement results of Mo-Re alloys. - The discussion of the values ...

International Nuclear Information System (INIS)

Surface analytical studies of high nitrogen austenitic stainless steels exposed to deaerated 0.1M HCl have revealed that nitrogen alloying additions influence the composition of salt layers and the passive film/alloy interface. In this study the authors employ electrochemical techniques and variable angle X-ray Photoelectron Spectroscopy (XPS) to examine the passive films formed on a series of austenitic stainless steels, Fe18Cr8Ni, Fe18Cr8Ni0.2N, Fe20Cr20Ni, Fe20Cr20Ni6Mo and Fe20Cr20Ni6Mo0.2N, in acidic chloride aqueous solution. In addition, several other model alloys, Fe19Cr, Fe19Cr9Ni, Fe19Cr2.5Mo, and Fe19Cr9Ni2.5Mo, were examined before and after electrochemical surface nitriding, a technique proven to have an effect analogous to N alloying. It was shown that nitrogen, nickel and molybdenum additions independently and in certain combinations stimulate selective dissolution of iron, resulting in a ...

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This report presents the results of cladding technology development under the Coal-Fired Combined Cycle DOE Project. Clad Alloy Development, involved the selection, fabrication and burner rig evaluation of advanced clad alloy composition diffusion-bonded to IN-738. Testing was conducted for up to 5800 hours at 1600/sup 0/F in a simulated PFB environment. Metallographic evaluation showed Co-base cladding alloys PFB-5PM and PFB-6PM (aluminided) and Fe-base alloy GE-2541 to be the most corrosion resistant. The formability and fabricability of sheet material was significantly improved for these alloys by utilizing powder metallurgy techniques. Clad Process Development encompassed processing activities to evaluate sheet alloy formability, bucket surface preparation techniques, platform clad forming, and the activated ...

International Nuclear Information System (INIS)

German (1975). Germany Borgs, JW Fabbri, R. Grueter, JW Khan,

International Nuclear Information System (INIS)

Based on information contained in literature, patents and catalogs a review is presented of powder-rolling metallurgy abroad. Statistics are given on the output of powder metallurgy in several countries. In the USA both the dense type of rolled metal for manufacturing various machine parts and the porous variety for making filters are produced. Four main types of technological processes are analysed: the usual flow chart for cold rolling, rolling of preheated powder, rolling in free-flowing state, and rolling with heated rollers. Of these four processes the first is most widely used. Fowders consisting of spherical particles (heat-stable alloys from nickel or high titanium alloys), which are difficult to work with, have not yet found wide practical application in powder metallurgy abroad. Literature data show that granulated heat-resistant alloys can be cold-treated under pressure only after they are ...

International Nuclear Information System (INIS)

Semiconductor properties of passive films formed on the Fe-18Cr alloy in a borate buffer solution (pH = 8.4) and 0.1 M H_2SO_4 solution were examined using a photoelectrochemical spectroscopy and an electrochemical impedance spectroscopy. Photo current reveals two photo action spectra that derived from outer hydroxide and inner oxide layers. A typical n-type semiconductor behaviour is observed by both photo current and impedance for the passive films formed in the borate buffer solution. On the other hand, a negative photo current generated, the absolute value of which decreased as applied potential increased in the sulfuric acid solution. This indicates that the passive film behaves as a p-type semiconductor. However, Mott-Schottky plot revealed the typical n-type semiconductor property. It is concluded that the passive film on the Fe-18Cr alloy formed in the borate buffer solution is composed of both n-type outer hydroxide and inner oxide ...

International Nuclear Information System (INIS)

An ampoule corrosion tests technique is presented for making a comparative corrosion-proof estimation of austenitic steels and alloys which are candidate materials for the ITER first wall and shield blanket. Influence of Cl"- on the rate and character of corrosion cracking has been determined. The dependence of time before destruction on Cl"- contents was obtained by experiments in twice-distilled water at a Cl"- content value of less than 0.05 mg/l. Kinetics of a corrosion crack growth has been determined by way of acoustic emission and measurement of electrical resistance. It has been revealed, that corrosion cracking of 316L and 316Ti steels in water with 100 mg/l of Cl"- takes place at temperatures over 50 C. For 316L (Russian analogue), 316Ti, 08Cr18Ni10Ti (type 304), 00Cr16Ni15Mo3Nb (type 316) steels and CrNiMo-1 (42-47%Cr, 1%Mo, Ni-base) alloy corrosion long-term strength and crack-resistance characteristics were ...

Energy Technology Data Exchange (ETDEWEB)

Thin film ultraviolet detectors based on hydrogenated amorphous silicon alloys are realized with different diode structures (PIN, NIP, PN, and NP). The PIN and NIP detectors exhibit higher sensitivity in the ultraviolet spectrum and a significant lower dark current in comparison to the PN or NP structures. The best detector performance was achieved with a 33 nm thick PIN diode. This detector shows a maximum of quantum efficiency of 36.3% at a wavelength of 310 nm. By varying the thickness of the semi-transparent Ag front contact the selectivity of the detectors with the quantum efficiency peak at 320 nm can be adjusted. Thus, the spectral sensitivity of the detector shifts from a broad UV to a selective UV-B spectrum. (orig.)

International Nuclear Information System (INIS)

Up to 90% of the life time of cyclically loaded components is determined by short crack initiation and propagation. This stage of the fatigue damage process is strongly influenced by microstructural features, e.g. grain boundaries and crystallographic grain orientation. Therefore LEFM can not be applied in a reasonable manner explaining the demand for a mechanism-related modelling method. The present study deals with mechanical testing and microstructural examinations applied to the relatively new #beta#-titanium alloy LCB. The results are used as data base to develop a new short crack model that is based on the model of Navarro and de los Rios. By using various techniques such as electron back-scattered diffraction and finite-element calculations the origin of crack initiation is revealed and the characteristics of crack propagation is determined. (orig.)

Science.gov (United States)

New sets of cross sections for the production of krypton isotopes from targets of Rb, Sr, Y, and Zr were constructed primarily on the bases of experimental excitation functions for Kr production from Y. These cross sections were used to calculate galactic-cosmic-ray and solar-proton production rates for Kr isotopes in the moon. Spallation Kr data obtained from ilmenite separates of rocks 10017 and 10047 are reported. Production rates and isotopic ratios for cosmogenic Kr observed in ten well-documented lunar samples and in ilmenite separates and bulk samples from several lunar rocks with long but unknown irradiation histories were compared with predicted rates and ratios. The agreements were generally quite good. Erosion of rock surfaces affected rates or ratios for only near-surface samples, where solar-proton production is important. There were considerable spreads in predicted-to-observed production rates of /sup 83/Kr, due at least in part ...

Energy Technology Data Exchange (ETDEWEB)

The high-temperature enthalpy increments of the phosphates La{sub 1/3}Zr{sub 2}(PO{sub 4}){sub 3}, Nd{sub 1/3}Zr{sub 2}(PO{sub 4}){sub 3}, Eu{sub 1/3}Zr{sub 2}(PO{sub 4}){sub 3} and Lu{sub 1/3}Zr{sub 2}(PO{sub 4}){sub 3} have been measured by high-temperature drop calorimetry in the temperature range 484.5-1090.7 K. From these results the heat capacity of the studied compounds has been derived.

Energy Technology Data Exchange (ETDEWEB)

Two isothermal sections were prepared at 1000 and 1150 C showing the low-Zr phases of the system Fe-Al-Zr. The phase equilibria were determined by means of X-ray powder diffractometry and electron beam microanalysis. For initial characterisation of mechanical properties, hardness values are determined and added to the tabulated data. (orig./MM) [German] Es werden am Fe-Al-Zr-System zwei isotherme Schnitte durch den zirkoniumarmen Teil des Systems bei 1000 und 1150 C erstellt. Die auftretenden Phasengleichgewichte werden mit Hilfe der Roentgenpulverdiffraktometrie und Elektronenstrahlmikroanalyse aufgeklaert. Zusaetzlich werden zur ersten Charakterisierung der mechanischen Eigenschaften Haertewerte bestimmt.

Energy Technology Data Exchange (ETDEWEB)

Stress corrosion cracking tests in constant extension rate tensile (CERT) and constant load tensile (CLT) tests were conducted on Ni-xCr- 9Fe-yC in Ar, water, and a LiOH-boric acid solution. Cr and C improve the resistance of Ni-base alloys to IG cracking in both Ar and water at 360C. Since creep plays a role in IG cracking, one possible explanation for the role of the environment involves its effect on the creep. Experiments were conducted on the role of C in the deformation behavior and failure mode of Ni-16Cr-9Fe. Constant load experiments were conducted on Ni-16Cr-9Fe to determine if the CLT test is more aggressive than CERT. The electron backscattering technique in a SEM is being developed in order to extend the IG cracking studies to grain sizes typical of commercial alloys, 20-30 microns.

Energy Technology Data Exchange (ETDEWEB)

Weldability and high temperature strength properties of Hastelloy Alloy XR were investigated in order to evaluate the materials performance of base metal and filler metal for the High Temperature Engineering Test Reactor (HTTR) uses. The weldability was examined by means of the chemical analysis in the deposited metals, optical microscopy, FISCO test, hardness measurements and bend test. The high temperature strength properties were investigated through tensile tests at R.T., 800, 900 and 950degC in air, and creep and creep rupture tests at 900 and 950degC in air. The results obtained by each test showed favorable performance. In particular, the bend test which is considered to be critical pass demonstrated low susceptibility to weld cracking through the optimization of B and C contents in the filler metal and by narrowing the groove. Creep rupture strength was nearly equal or higher than those of Hastelloy Alloy XR master ...

International Nuclear Information System (INIS)

The layered GdBa_0_._5Sr_0_._5Co_2O_5_+_#delta# (GBSC) perovskite oxides are synthesized by modified Pechini method and investigated as a novel cathode material for solid oxide fuel cells (SOFCs) based on a stable perovskite oxide BaCe_0_._5Zr_0_._3Y_0_._1_6Zn_0_._0_4O_3_-_#delta# (BCZYZ) as electrolyte. The fabricated single cells of NiO-BCZYZ/BCZYZ (#approx#20 #mu#m)/GBSC (#approx#20 #mu#m) were operated from 550 to 700 "oC with humidified hydrogen (#approx#5% H_2O) as fuel. The BCZYZ perovskite electrolyte was completely dense after sintered at 1250 "oC for 5 h, lower than that without zinc dopant about 150 "oC. An open circuit voltage of 1.009 V and a maximal power density of 0.35 W cm"-"2 were achieved at 700 "oC. The interfacial polarization resistance was as low as 1.46, 0.45, 0.25 and 0.15 #OMEGA# cm"2 at 550, 600, 650 and 700 "oC, respectively. The ratio of polarization resistance to total cell resistance decreased with the increase in ...

Energy Technology Data Exchange (ETDEWEB)

The use of radiochemical detectors in the A approx. = 90 mass region to measure 14 MeV neutron fluences is investigated from the standpoint of cross section sensitivities. Specifically, /sup 90/Zr and /sup 89/Y neutron-induced cascades leading to the production of /sup 89/Zr, /sup 88/Zr, /sup 88/Y, and /sup 87/Y are studied in a one-energy-group approximation, and the sensitivities of the measured ratios R/sub Z/ = /sup 88/Zr//sup 89/Zr and R/sub Y/ = /sup 87/Y//sup 88/Y to the input cross sections are delineated. The most sensitive cross section in each cascade is the cross section that dominates the production of the final isotope in the chain. Only one of the isomeric levels in /sup 90/Zr contributes importantly to the Zr cascade. Burnback (n,..gamma..) and burnup (n,p) reactions are also considered. The (n,..gamma..) effects are small, ...

Energy Technology Data Exchange (ETDEWEB)

A joint materials test program developed by the Institute for Mining and Minerals Research (IMMR) and the Tennessee Valley Authority (TVA) involved the postexposure mechanical properties and corrosion behavior of candidate structural materials in an experimental, atmospheric fluidized-bed combustor (AFBC). This combustor was operated by Accurex Corporation at Research Triangle Park, North Carolina, under the direction of TVA. The materials studied were Type 304, Type 310, and INCOLOY alloy 800 in the form of disc coupons with and without crevice configurations. Type 304 was also used for mechanical property measurements. The alloys were exposed to the combustor environment at about840/sup 0/C for approximately 330 hours. The ranking in terms of decreasing weight loss was: (1) Type 304, (2) Type 310, and (3) INCOLOY alloy 800. The presence of tight crevices did not enhance the corrosion rate. In addition, the corrosion ...

Energy Technology Data Exchange (ETDEWEB)

Four subprojects were completed: development and evaluation of die coatings, accelerated die life characterization of die materials, evaluation of fluid flow and solidification modeling programs, selection and characterization of Al-based die casting alloys, and influence of die materials and coatings on die casting quality.

International Nuclear Information System (INIS)

The main compositions of iron-base amorphous self-fluxing alloy powders of 150 mesh, used in this work, are Fe, Cr, Ni, W, Mo, B, Si and C. The ranges of each element in at% are (65-70)Fe, (3-5)Cr, (2-4)Ni, (2-4)W, (1-2)Mo, (10-14)B, (4-7)Si and (2-3)C. The atomic ratio of metal-metalloid is about 80:20, so this alloy is abbreviated as M_8_0X_2_0. The material on which coatings were deposited is 1020 steel, austenitized for 1h at 880 C, water quenched, and tempered at 180 C for 1h. This heat treatment resulted in a low carbon martensite structure with a hardness of HRC35-45. After cleaning, shot blasting and preheating the steel to about 200 C, the authors sprayed a thin Ni-Al alloy layer of about 0.1--0.15mm in thickness onto the specimen by means of an oxygen-acetylene torch to provide better bonding of the coating with substrate. Then the M_8_0X_2_0 and M_8_0X_2_0+8%CeO_2 alloy ...

International Science & Technology Center (ISTC)

Determination of Special Molybdenum Alloys Optimal Structure Using the Cybernetic Method

International Science & Technology Center (ISTC)

Development of the Corrosion Protection Technology for Special Steels and Alloys

International Nuclear Information System (INIS)

In order to improve the reliability of PWR steam generators, we have performed research to improve the tubing material and tube-support-plate configuration, based on our wide operating experience, and have developed and verified Alloy TT690 as the optimum tubing material and the BEC (Broached Egg Crate) type tube-support design. In the research, we have studied the metallurgical mechanism of the alloy to improve its corrosion resistance, evaluated corrosion susceptible region quantitatively, estimated the actual environment in a steam generator and confirmed the reliability by a model boiler test over a long period. It has been verified that the steam generator with the latest design has higher reliability with respect to the corrosion resistance of tubes. (author).

Energy Technology Data Exchange (ETDEWEB)

Mechanical alloying is an important pre-requisite for the manufacturing of heat resistant oxide-dispersion-strengthened superalloys. Though the microstructure of these materials after hot extrusion and recrystallization treatment is well documented, little is known about the microstructural evolution during ball-milling. A method was tested to prepare electron transparent foils and extraction replica from powder particles for TEM investigations. The microstructure was found to consist of a Ni-Cr-Al solid solution in which submicron particles of refractory metals were embedded. The extremely fine grainize of about 50 nm is the consequence of severe plastic deformation. Yttria particles could not be detected in the powder after ball milling, but after a heat treatment at 1000 C the well-known fine dispersion of oxide particles was evident. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Materials for the construction of cold neutron sources must satisfy a range of demands. The cryogenic temperature and irradiation create a severe environment. Candidate materials are identified and existing cold sources are briefly surveyed to determine which materials may be used. Aluminum- and magnesium-based alloys are the preferred materials. Existing data for the effects of cryogenic temperature and near-ambient irradiation on the mechanical properties of these alloys are briefly reviewed, and the very limited information on the effects of cryogenic irradiation are outlined. Generating mechanical property data under cold source operating conditions is a daunting prospect. It is clear that the cold source material will be degraded by neutron irradiation, and so the cold source must be designed as a brittle vessel. The continued effective operation of many different cold sources at a number of reactors makes it clear ...

International Nuclear Information System (INIS)

The grain size dependence of the tensile properties and the deformation mechanisms responsible for those properties are examined for Mg alloy, AZ31B, sheet. Specifically, the Hall-Petch effect and strain anisotropy (r-value) are characterized experimentally, and interpreted using polycrystal plasticity modeling. {1 0 . 2} extension twins, {1 0 . 1} contraction twins, and so-called 'double-twins' are observed via microscopy and diffraction-based techniques, and the amount of twinning is found to increase with increasing grain size. For the sheet texture and tensile loading condition examined, {1 0 . 2} extension twinning is not expected, yet the polycrystal plasticity model predicts the observed behavior, including this 'anomalous' tensile twinning. The analysis shows that the Hall-Petch strength dependence, of the polycrystal as a whole, is primarily determined by the grain size dependence of the strength of the prismatic slip systems.

International Nuclear Information System (INIS)

The gliding modes of a duplex Ti-6Al-4V titanium alloy were investigated through in situ (scanning electron microscopy) tensile tests. A method based on electron back-scattering diffraction (EBSD) measurements was used to identify activated slip systems. The approach applied to a large number of grains allowed a statistical analysis of the nature (basal, prismatic, pyramidal) and distribution of the slip systems according to the crystallographic texture. A discussion concerning the pertinence of Schmid's law to explain the occurrence and succession of slip events is then proposed. The domain in favor of each type of slip system is finally presented by using inverse pole figures mapped with Schmid's factor iso-curves.

Energy Technology Data Exchange (ETDEWEB)

Ti and its alloys (Ti-6Al-4V) have been used in different engineering applications due to their several outstanding properties. Nevertheless, their use in practical applications is limited in many cases due to their poor tribological property. Researches are ongoing on surface modification of Ti based materials by different plasma and ion based techniques to overcome this problem. However, the conventional plasma nitriding techniques have several problems such as formation of an arc, increased possibility of surface contamination due to a comparatively higher operating pressure, production of a very thin nitrided layer after a long processing time, etc. In this present work, the possibility of a new low-pressure plasma nitriding process using a Plasma Enhanced Chemical Vapor Deposition (PECVD) based saddle field fast atom beam source on a Ti-6Al-4V alloy sample is investigated. ...

Energy Technology Data Exchange (ETDEWEB)

The results of the creep performance studies at temperatures from 700-1000 C with welds of alloy 800 HT, the manual shielded metal arc welds made with Githerm 85 and Grini 209 filler metals, as well as the MIG pulsed arc welds made with the Nicrofer S 206 and Nicrofer S 5520 filler metals, proved to be in very good agreement with the calculated characteristic values published on VdTUeV sheet 434 in comparative assessments based on creep values valid for a service period of 10 000 hours. The MIG pulsed arc weld made with the Nicrofer S 5520 filler metal achieved by far the best results and strength values comparable to those of the base material, whereas the values of the other welds were corresponding to calculated strength values of the base material reduced by 20%. (orig./CB) [Deutsch] Die im Temperaturbereich von 700-1000 C an Alloy 800 HT und den ...

International Nuclear Information System (INIS)

The masses of the proton-rich nuclides "8"5","8"6","8"7Mo and "8"7Tc have been measured with the Penning trap mass spectrometer SHIPTRAP at GSI. The measured mass excesses of these nuclei deviate from the values of the Atomic Mass Evaluation 2003 by up to 1.6 MeV, indicating a systematic shift of the mass surface in this region compared to previous measurements. A local mass extrapolation based on the new results has been made for the mass range A=80-95. Measured and extrapolated mass values and the derived separation energies have been compared to theoretical mass models. Taking into account the new mass excess values, rp-process network calculations have been performed. Preliminary results show changes in the final abundances for A=86-92 by up to a factor of 30. Results of measurements and calculations are presented, and the issue of a potential Zr-Nb cycle is addressed.

Energy Technology Data Exchange (ETDEWEB)

The leakage current behaviors of PLZT capacitors with top electrodes of Pt, Ir, and IrO{sub 2} are investigated before and after hydrogen forming gas anneal. The P-E hysteresis and fatigue properties of Pt/PLZT/Pt capacitors are almost recovered after recovery anneal in O{sub 2} ambient. The leakage current mechanisms of PLZT capacitors with Pt and IrO{sub 2} top electrodes are consistent with space-charge influenced injection model showing the strong time dependence irrespective of annealing conditions. On the other hand, the leakage current behavior of Ir/PLZT/Pt capacitor shows steady state independent of time because IrPb, conducting phase, formed at interface between Ir top and PLZT is a high conduction path. Teh leakage current mechanism of Ir/PLZT/Pt capacitor is consistent with Schottky barrier model. (author). 15 refs., 6 figs.

Energy Technology Data Exchange (ETDEWEB)

In this study, isothermal torsion tests were carried out on magnesium AZ31B alloy under constant strain rate conditions, in the range of 250 to 400 C at 0.01, 0.1, and 1.0 s{sup -1}. Alloy flow stress dependence on strain rate and temperature can be described by a power law with activation energy of 130 kJ/mol. Microstructural examination of hot deformed samples shows very fine recrystallized grains decorating grain boundaries of larger gains in the form of a necklace. These fine grains are produced by dynamic recrystallization at the grain boundaries of original grains. Microstructure evolution, based on samples quenched at different strain levels, indicates that increasing deformation strain has little effect on recrystallized grain size but widens the recrystallized region, with full recrystallization achieved at a certain high strain level. Recrystallized grain size increases with increasing deformation temperature and ...

Energy Technology Data Exchange (ETDEWEB)

The excellent high temperature strength and thermal conductivity of molybdenum-base alloys provide attractive features for components in advanced magnetic and inertial fusion devices. Refractory metal alloys react readily with oxygen and other gases. Oxidized molybdenum in turn is susceptible to losses from volatile molybdenum trioxide species, (MoO3)m, in air and the hydroxide, MoO2(OH)2, formed from water vapor. Transport of radioactivity by the volatilization, migration, and re-deposition of these volatile species during a potential accident involving a loss of vacuum or inert environment represents a safety issue. In this report we present experimental results on the oxidation, volatilization and re-deposition of molybdenum from TZM in flowing air between 400 and 800°C. These results are compared with calculations obtained from a vaporization mass transfer model using chemical thermodynamic data for vapor ...

Energy Technology Data Exchange (ETDEWEB)

Powders with nominal compositions (in atomic percent) Ti-48Al and Ti-48Al-2Nb-2Cr were prepared by the plasma rotating electrode process (PREP) and gas atomization (GA) techniques. As-solidified and heat-treated (1000degC per 3 h) powder samples were examined by metallography, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The microstructures of the powders were characterized as a function of atomization technique, alloy content, powder particle size (solidification rate) and thermal history. All of the as-solidified powders were comprised of disordered [alpha], and ordered [alpha][sub 2]-Ti[sub 3]Al and [gamma]-TiAl. For both alloys, a larger volume fraction of [alpha] and [alpha][sub 2] was observed in the PREP powders relative to GA powders of comparable size. Additionally, for both alloys and both atomization techniques, the volume fraction of [alpha][sub 2] was observed to ...

Energy Technology Data Exchange (ETDEWEB)

In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good ...

International Nuclear Information System (INIS)

The purpose of this research is to investigate the micro-mechanism of deformation behavior of metallic glasses. We report the results of direct observations of short-range and medium-range structural change during tensile deformation of metallic glasses by high energy X-ray diffraction method. Cu50Zr50 and Ni30Zr70 metallic glass samples in the ribbon shape (1.5 mm width and 25 ?m) were made by using rapid quenching method. Tensile deformation added to the sample was made by using special equipment adopted for measuring the high energy X-ray diffraction. The peaks in pair distribution function g(r) for Cu50Zr50 and N30iZr70 metallic glasses move zigzag into front and into rear during tensile deformation. These results of direct observation on atomic distribution change for Cu50Zr50 and Ni30Zr70 metallic glass ribbons during tensile deformation suggest that the ...

Energy Technology Data Exchange (ETDEWEB)

Out of the R and D of mesoscopic metal group composite materials, the paper described the fiscal 1997 results. In the in-situ method as a composite material making method, elucidated to some degree were chemical composition of Fe-C-Cr-V-Nb-Mo-W-Ni base multi-dimensional alloys, and wear resistance and oxidation resistance of MC type carbide dispersion multi-phase texture crystallizing as primary crystal and eutectic. In the composite material making with ceramic fiber and alloy by the pressure infiltration method, the paper clarified the texture formation mechanism in solidification/heat treatment by a combination of Al alloys and alumina long fiber, and the relation between fiber configuration and wear resistance. By MA and MG methods as the powder metallurgy composite material making method, a composed body of {alpha}-stainless steel of Fe-12%Cr composition and M23C6 of 40-90vol% are designed for ...