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Sample records for barium base alloys

  1. Barium zirconate base ceramics

    International Nuclear Information System (INIS)

    The chemical corrosion at high temperatures is a serious problem in the refractory materials field, leading to degradation and bath contamination by elements of the refractory. The main objective of this work was to search for ceramics that could present higher resistance to chemical attack by aggressive molten oxides. The general behaviour of a ceramic material based on barium zirconate (Ba Zr O3) with the addition of different amounts of liquid phase former was investigated. The densification behaviour occurred during different heat treatments, as well as the microstructure development, as a function of the additives and their reactions with the main phase, were observed and are discussed. (author)

  2. Effects of Different Barium Compounds on the Corrosion Resistance of Andalusite-Based Low-Cement Castables in Contact with Molten Al-Alloy

    Science.gov (United States)

    Adabifiroozjaei, Esmaeil; Koshy, Pramod; Rastkerdar, Ebad

    2011-08-01

    An experimental study was conducted to investigate the interfacial phenomena between an Al alloy and andalusite low-cement castables (LCCs) containing fixed contents of barium compounds (BaO, BaSO4, and BaCO3) at 1123 K and 1433 K (850 °C and 1160 °C) using the Alcoa cup test. Interfacial reaction products and phases formed during heat treatment of the refractory samples were characterized using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) and X-ray diffraction analysis (XRD). The addition of both BaO and BaSO4 led to a significant reduction of alloy penetration into the refractory. Hexa-celsian formation was observed in both these refractories, which drastically increased their corrosion resistance. Barite decomposition was observed at 1373 K (1100 °C) in the presence of alumina and silica, which was the precursor for hexa-celsian formation. Barium silicates were formed in all samples containing additives; however, this did not have any major influence on the corrosion resistance. Solidified eutectics of BaSi2 and α-BaAl2Si2 formed in all these samples, which acted as an interfacial barrier that prevented additional molten aluminum penetration; however, the positive effect of intermetallic formation was offset by glassy phase formation in samples containing BaCO3 as the additive.

  3. Barium

    International Nuclear Information System (INIS)

    Present article is devoted to barium content in fluoride. In order to obtain the comprehensive view on barium distribution in fluorite 303 mono mineral fractions of various geologic deposits and ores of Kazakhstan, Uzbekistan, Tajikistan and some geologic deposits of Russia were analyzed. The barium content in fluorite of geologic deposits of various mineralogical and genetic type was defined. The basic statistical estimation of barium distribution in fluorite were evaluated.

  4. Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

    Science.gov (United States)

    Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

    2016-04-01

    Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution. PMID:26999358

  5. Ammonia synthesis with barium-promoted iron–cobalt alloys supported on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus; Chorkendorff, Ib; Jacobsen, Claus J.H.; Teunissen, Herman T.

    2003-01-01

    Iron–cobalt alloys supported on carbon were investigated as ammonia synthesis catalysts. Barium was found to have a promoting effect for Fe with an optimum atomic ratio Ba/Fe of 0.35. At this Ba loading, a local maximum for the NH3 synthesis activity was found at 4 wt% Co by varying the Fe/Co ratio....... Samples containing only Co and no Fe, however, yielded by far the most active catalysts (7.0 μmol (NH3) g−1 s−1, 673 K, 10 bar). Barium was a very efficient promoter for Co, increasing the NH3 synthesis activity by more than two orders of magnitude compared to the unpromoted Co samples, while it was not...

  6. The high-temperature sulphation behavior of barium-based sorbents during coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, J.; Li, N.; Zhou, J.; Cao, X.; Liu, J.; Zhao, X.; Cen, K.

    2000-07-01

    In order to promote the sulfur removal efficiency during coal combustion, the high-temperature sulfation behavior of barium-based sorbents was studied. The sulfation product BaSO{sub 4} which did not decompose until 1,580 C had much better thermal stability than CaSO{sub 4} which rapidly decomposed at about 1,300 C. The desulfurization effect of barium salt Ba{sup 2+} was much better than calcium salt Ca{sup 2+} during coal combustion at about 1,200{approximately}1,300 C. The sulfur removal efficiency of barium-based sorbents could achieve 35.5% in industrial grate furnace.

  7. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    Science.gov (United States)

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. PMID:26794953

  8. A novel barium polymeric membrane sensor for selective determination of barium and sulphate ions based on the complex ion associate barium(II)-Rose Bengal as neutral ionophore

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A.M. [Genetic Engineering and Biotechnology Research Institute (GEBRI), Minufiya University, Sadat City (Egypt); El-Shahawi, M.S. [Chemistry Department, Faculty of Science at Damiatta, Mansoura University, Damiatta, Dumyat 34517 (Egypt)]. E-mail: mohammad_el_shahawi@yahoo.co.uk; Abdel-Azeem, M. [Chemistry Department, Faculty of Science at Damiatta, Mansoura University, Damiatta, Dumyat 34517 (Egypt)

    2006-01-12

    A simple, long life, rapid response and sensitive barium(II)-PVC membrane sensor that typically follows Nernstian behavior has been developed for the assay of barium(II) ions. The developed sensor has been made by incorporating the complex ion associate of barium(II)-Rose Bengal (Ba-RB) as an ionophore into a plasticized PVC matrix. The sensor is stable and exhibited fast potential response of 20 s and gave a good linear response with a Nernstian slope of 28.5 {+-} 0.4 mV/decade of activity within the concentration range 5 x 10{sup -5} to 10{sup -1} M over a wide range of pH 4.5-10.0 for barium(II) ions. The developed sensor showed comparatively good selectivity for barium(II) ions with respect to other alkali, alkaline earth, transition and heavy metal ions. The plasticizer o-nitrophenyloctyl ether controlled significantly the calibration slope and the lifetime of the fabricated sensor. The proposed sensor was used successfully for the analysis of barium(II) ions in wastewater samples and in lithophone pigment with excellent recovery percentages in the range 98.9-99.8 {+-} 1.6%. The determination of sulphate in fresh and potable water samples with the developed sensor has been also achieved successfully. The described sensor provides a reliable means with good correlation with the data obtained by atomic absorption spectrometry (AAS) and other spectrophotometric methods for the analysis of trace amounts of barium(II) and/or sulphate ions in different matrices.

  9. A novel barium polymeric membrane sensor for selective determination of barium and sulphate ions based on the complex ion associate barium(II)-Rose Bengal as neutral ionophore

    International Nuclear Information System (INIS)

    A simple, long life, rapid response and sensitive barium(II)-PVC membrane sensor that typically follows Nernstian behavior has been developed for the assay of barium(II) ions. The developed sensor has been made by incorporating the complex ion associate of barium(II)-Rose Bengal (Ba-RB) as an ionophore into a plasticized PVC matrix. The sensor is stable and exhibited fast potential response of 20 s and gave a good linear response with a Nernstian slope of 28.5 ± 0.4 mV/decade of activity within the concentration range 5 x 10-5 to 10-1 M over a wide range of pH 4.5-10.0 for barium(II) ions. The developed sensor showed comparatively good selectivity for barium(II) ions with respect to other alkali, alkaline earth, transition and heavy metal ions. The plasticizer o-nitrophenyloctyl ether controlled significantly the calibration slope and the lifetime of the fabricated sensor. The proposed sensor was used successfully for the analysis of barium(II) ions in wastewater samples and in lithophone pigment with excellent recovery percentages in the range 98.9-99.8 ± 1.6%. The determination of sulphate in fresh and potable water samples with the developed sensor has been also achieved successfully. The described sensor provides a reliable means with good correlation with the data obtained by atomic absorption spectrometry (AAS) and other spectrophotometric methods for the analysis of trace amounts of barium(II) and/or sulphate ions in different matrices

  10. Individual-specific transgenerational marking of fish populations based on a barium dual-isotope procedure.

    Science.gov (United States)

    Huelga-Suarez, Gonzalo; Moldovan, Mariella; Garcia-Valiente, America; Garcia-Vazquez, Eva; Alonso, J Ignacio Garcia

    2012-01-01

    The present study focuses on the development and evaluation of an individual-specific transgenerational marking procedure using two enriched barium isotopes, (135)Ba and (137)Ba, mixed at a given and selectable molar ratio. The method is based on the deconvolution of the isotope patterns found in the sample into four molar contribution factors: natural xenon (Xe nat), natural barium (Ba nat), Ba135, and Ba137. The ratio of molar contributions between Ba137 and Ba135 is constant and independent of the contribution of natural barium in the sample. This procedure was tested in brown trout ( Salmo trutta ) kept in captivity. Trout were injected with three different Ba137/Ba135 isotopic signatures ca. 7 months and 7 days before spawning to compare the efficiency of the marking procedure at long and short term, respectively. The barium isotopic profiles were measured in the offspring by means of inductively coupled plasma mass spectrometry. Each of the three different isotopic signatures was unequivocally identified in the offspring in both whole eggs and larvae. For 9 month old offspring, the characteristic barium isotope signatures could also be detected in the otoliths even in the presence of a high and variable amount of barium of natural isotope abundance. In conclusion, it can be stated that the proposed dual-isotope marking is inheritable and can be detected after both long-term and short-term marking. Furthermore, the dual-isotope marking can be made individual-specific, so that it allows identification of offspring from a single individual or a group of individuals within a given fish group. PMID:22103693

  11. Terbium base alloy

    International Nuclear Information System (INIS)

    Composition of terbium-5-7 % gadolinium alloy with high magnetostriction sensitivity (180x10-8 Oe) is suggested. The alloy is designed for usage under cryogenic temperature within 500-1500 Oe fields. Magnetostriction sensitivity of the suggested alloy is by 2-2.5 times higher, than that of well-known before one. 1 tab

  12. CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging

    OpenAIRE

    Stuart A Taylor; Slater, Andrew; Burling, David N.; Tam, Emily; Greenhalgh, Rebecca; Gartner, Louise; Scarth, Julia; Pearce, Robert; Bassett, Paul; Halligan, Steve

    2007-01-01

    To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately af...

  13. Barium enema

    Science.gov (United States)

    Barium enema is a special x-ray of the large intestine, which includes the colon and rectum. ... to a bag that holds a liquid containing barium sulfate. This is a contrast material that highlights ...

  14. Barium Sulfate

    Science.gov (United States)

    Barium sulfate is used to help doctors examine the esophagus (tube that connects the mouth and stomach), ... dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called ...

  15. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    International Nuclear Information System (INIS)

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl2 nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI2 is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu2+/Eu3+ ratio in the glass ceramics should be determined and optimize favor of the Eu2+. We also want to distinguish between Eu2+ in the glass matrix and Eu2+ in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a CaF2 host lattice were carried out. (orig.)

  16. Uranium-Based Cermet Alloys

    International Nuclear Information System (INIS)

    The paper describes certain features of dispersion-hardened uranium-based cermets. As possible hardening materials, consideration was given to UO2, UC, Al2O3, MgO and UBe13. Data were obtained on the behaviour of uranium alloys containing the above-mentioned admixtures during creep tests, short-term strength tests and cyclic thermal treatment. The corrosion resistance o f UBe13-based uranium alloys was also studied. )author)

  17. Synthesis of strontium substituted barium titanate nanoparticles by mechanical alloying and high power ultrasonication destruction

    Science.gov (United States)

    Yustanti, Erlina; Hafizah, Mas Ayu Elita; Manaf, Azwar

    2016-04-01

    This paper reports the particle and crystallite size characterizations of mechanically alloyed Ba(1-x)SrxTiO3 (BST) with x = 0.3 and 0.7 prepared with the assistance of a high-power sonicator. Analytical grade BaCO3, TiO2 and SrCO3 precursors with a purity of greater than 99 wt.% were mixed and milled using a planetary ball mill to a powder weight ratio of 10:1. Powders obtained after 20 hours of milling time were then sintered at 1200°C for 4 hours to form crystalline powders.These powders were further treated ultrasonically under a fixed 6.7 gr/l particle concentration in demineralized water for 1, 3, 5, 7 hours and a fixed ultrasonic irradiation time of 1 hour to the dispersion of 6.7; 20; 33.3 gr/l concentrations. As to the results of crystallite size characterization, it is demonstrated that the mean crystallite size of BST with x = 0.3 and 0.7 undergo a slight change after the first 1 hour irradiation time and then remain almost unchanged. This was in contrary to the particle size in which the mean particle size of BST with x = 0.3 increased from 765 nm to 1405 nm after 7 hours irradiation time, while that of x = 0.7 increased from 505 nm to 1298 nm after 3 hours and then reduced back to the initial size after 7 hours ultra sonication time. The increase in particle size was due to large of cohesive forces among fine particles. It is also demonstrated that the concentration of particles in a dispersion with anionic surfactant do not effective to reduce the particle sizes ultrasonically. Nanoparticles with the mean size respectively 40 and 10 times larger than their respective crystallite size were successfully obtained respectively in x = 0.3 and x = 0.7.

  18. Capacitively coupled electrolyte-conductivity sensor based on high-k material of barium strontium titanate

    OpenAIRE

    Huck, C.; Poghossian, A; Baecker, M; Chaudhuri, S.; Zander, W; Schubert, J.; Begoyan, V. K.; Buniatyan, V. V.; Wagner, Patrick Hermann; Schoening, M. J

    2014-01-01

    A miniaturized capacitively coupled contactless conductivity detection (C4D) sensor based on high-kperovskite oxide of barium strontium titanate (BST) has been implemented for the first time. The BST films(∼120 nm thick) of Ba0.25Sr0.75TiO3composition were prepared on a p-Si-SiO2-Pt structure by pulsed laserdeposition technique using BST targets fabricated by the self-propagating high-temperature synthesismethod. The Pt electrodes were buried into the SiO2layer to obtain a planar structure. F...

  19. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    Energy Technology Data Exchange (ETDEWEB)

    Selling, J.

    2007-07-01

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl{sub 2} nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI{sub 2} is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu{sup 2+}/Eu{sup 3+} ratio in the glass ceramics should be determined and optimize favor of the Eu{sup 2+}. We also want to distinguish between Eu{sup 2+} in the glass matrix and Eu{sup 2+} in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a

  20. CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Stuart A. [University College Hospital, Department of Specialist Radiology, London (United Kingdom); University College Hospital, Department of Imaging, London (United Kingdom); Slater, Andrew [John Radcliffe Hospital, Oxford (United Kingdom); Burling, David N.; Tam, Emily; Gartner, Louise; Scarth, Julia; Bassett, Paul [St Mark' s Hospital, Northwick Park (United Kingdom); Greenhalgh, Rebecca; Pearce, Robert; Halligan, Steve [University College Hospital, Department of Specialist Radiology, London (United Kingdom)

    2008-01-15

    To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76-94% segments graded 1), although best for regimen D (P = 0.02). Across all regimens, stool tagging quality was high (mean 3.7-4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P = 0.002). Detection of cancer (n = 2), polyps {>=}6 mm (n = 21), and {<=}5 mm (n = 72) was 100, 81 and 32% respectively, with only four false positives {>=}6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reduced-laxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy. (orig.)

  1. Nickel-base alloys combat corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, D.C. [VDM Technologies Corp., Houston, TX (United States); Herda, W. [Krupp-VDM GmbH, Werdohl (Germany)

    1995-06-01

    The modern chemical process industry must increase production efficiency to remain competitive. Manufacturers typically meet this challenge by utilizing higher temperatures and pressures, and more-corrosive catalysts. At the same time, the industry has to solve the technical and commercial problems resulting from rigid environmental regulations. To overcome these obstacles, new alloys having higher levels of corrosion resistance have been developed. These materials are based on increased understanding of the physical metallurgy of nickel-base alloys, especially the role of alloying elements. Results of many studies have led to innovations in nickel-chromium-molybdenum alloys containing both high and low amounts of nickel. Higher molybdenum and chromium contents, together with nitrogen additions, have opened up an entirely new class of alloys having unique properties. In addition, a new chromium-base, fully wrought super stainless steel shows excellent promise in solving many corrosion problems. These newer alloys have the ability to combat uniform corrosion, localized corrosion, and stress-corrosion cracking in the harsh halogenic environment of the chemical process industry. This article briefly lists some of the major highlights and corrosion data on recent nickel-chromium-molybdenum and nickel-molybdenum alloys, and the development of a chromium-base, wrought super-austenitic alloy known as Nicrofer 3033 (Alloy 33). Some comparisons with existing alloys are presented, along with a few commercial applications.

  2. Barium Sulfate

    Science.gov (United States)

    ... using x-rays or computed tomography (CAT scan, CT scan; a type of body scan that uses ... be clearly seen by x-ray examination or CT scan. ... more times before an x-ray examination or CT scan.If you are using a barium sulfate ...

  3. Nanocomposite thin films for miniaturized multi-ayer ceramic capacitors prepared from barium titanate nanoparticle based hybrid solutions

    OpenAIRE

    Schneller, T.; Halder, S; Waser, R.; Pithan, C.; Dornseiffer, J.; Shiratori, Y; Houben, L.; Vyshnavi, N.; Majumber, S.B.

    2011-01-01

    In the present work a flexible approach for the wet chemical processing of nanocomposite functional thin films is demonstrated. Barium titanate (BTO) based nanocomposite thin films for future miniaturized multi-layer ceramic capacitors are chosen as model systems to introduce the concept of "hybrid solutions" which consist of stabile mixtures of reverse micelle derived BTO nanoparticle dispersions and conventional molecular precursor solutions of either the same (BTO:BTO) or a specifically di...

  4. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio and a...... low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state are...... discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  5. Surface Bond Strength in Nickel Based Alloys

    OpenAIRE

    Ramesh, Ganesh; Padmanabhan, T. V.; Ariga, Padma; Joshi, Shalini; Bhuminathan, S.; Vijayaraghavan, Vasantha

    2012-01-01

    Bonding of ceramic to the alloy is essential for the longevity of porcelain fused to metal restorations. Imported alloys used now a days in processing them are not economical. So this study was conducted to evaluate and compare the bond strength of ceramic material to nickel based cost effective Nonferrous Materials Technology Development Center (NFTDC), Hyderabad and Heraenium S, Heraeus Kulzer alloy. An Instron testing machine, which has three-point loading system for the application of loa...

  6. Efficacy of Barium-Based Fecal Tagging for CT Colonography: a Comparison between the Use of High and Low Density Barium Suspensions in a Korean Population - a Preliminary Study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Ju; Park, Seong Ho; Lee, Seung Soo; Byeon, Jeong Sik; Kim, Jung Hoon; Kim, Yeoung Nam; Kim, Ah Young; Ha, Hyun Kwon [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Choi, Eugene K. [University of California Los Angeles, Los Angeles (United States)

    2009-02-15

    This preliminarily study was designed to determine and to compare the efficacy of two commercially available barium-based fecal tagging agents for CT colonography (CTC) (high-density [40% w/v] and low-density [4.6% w/v] barium suspensions) in a population in Korea. In a population with an identified with an average-risk for colorectal cancer, 15 adults were administered three doses of 20 ml 40% w/v barium for fecal tagging (group I) and 15 adults were administered three doses of 200 ml 4.6% w/v barium (group II) for fecal tagging. Excluding five patients in group I and one patient in group II that left the study, ten patients in group I and 14 patients in group II were finally included in the analysis. Two experienced readers evaluated the CTC images in consensus regarding the degree of tagging of stool pieces 6 mm or larger. Stool pieces were confirmed with the use of standardized CTC criteria or the absence of matched lesions as seen on colonoscopy. The rates of complete fecal tagging were analyzed on a per-lesion and a per-segment basis and were compared between the patients in the two groups. Per-lesion rates of complete fecal tagging were 52% (22 of 42; 95% CI, 37.7-66.6%) in group I and 78% (28 of 36; 95% CI, 61.7-88.5%) in group II. The difference between the two groups did not reach statistical significance (p = 0.285). The per-segment rates of complete tagging were 33% (6 of 18; 95% CI, 16.1%-56.4%) in group I and 60% (9 of 15; 95% CI, 35.7%-80.3%) in group II; again, the difference between the two groups did not reach statistical significance (p = 0.171). Barium-based fecal tagging using both the 40% w/v and the 4.6% w/v barium suspensions showed moderate tagging efficacy. The preliminary comparison did not demonstrate a statistically significant difference in the tagging efficacy between the use of the two tagging agents, despite the tendency toward better tagging with the use of the 4.6% w/v barium suspension.

  7. CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging

    International Nuclear Information System (INIS)

    To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76-94% segments graded 1), although best for regimen D (P = 0.02). Across all regimens, stool tagging quality was high (mean 3.7-4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P = 0.002). Detection of cancer (n = 2), polyps ≥6 mm (n = 21), and ≤5 mm (n = 72) was 100, 81 and 32% respectively, with only four false positives ≥6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reduced-laxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy. (orig.)

  8. Shape memory alloy based motor

    Indian Academy of Sciences (India)

    S V Sharma; M M Nayak; N S Dinesh

    2008-10-01

    Design and characterization of a new shape memory alloy wire based Poly Phase Motor has been reported in this paper. The motor can be used either in stepping mode or in servo mode of operation. Each phase of the motor consists of an SMA wire with a spring in series. The principle of operation of the poly phase motor is presented. The motor resembles a stepper motor in its functioning though the actuation principles are different and hence has been characterized similar to a stepper motor. The motor can be actuated in either direction with different phase sequencing methods, which are presented in this work. The motor is modelled and simulated and the results of simulations and experiments are presented. The experimental model of the motor is of dimension 150 mm square, 20 mm thick and uses SMA wire of 0·4 mm diameter and 125 mm of length in each phase.

  9. A plasmonic modulator based on metal-insulator-metal waveguide with barium titanate core

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2013-01-01

    We design a plasmonic modulator which can be utilized as a compact active device in photonic integrated circuits. The active material, barium titanate (BaTiO3), is sandwiched between metal plates and changes its refractive index under applied voltage. Some degree of switching of ferroelectric...

  10. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  11. Iron - based bulk amorphous alloys

    Directory of Open Access Journals (Sweden)

    R. Babilas

    2010-07-01

    Full Text Available Purpose: The paper presents a structure characterization, thermal and soft magnetic properties analysis of Fe-based bulk amorphous materials in as-cast state and after crystallization process. In addition, the paper gives some brief review about achieving, formation and structure of bulk metallic glasses as a special group of amorphous materials.Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 metallic glass in form of ribbons and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM methods. The thermal properties of the glassy samples were measured using differential thermal analysis (DTA and differential scanning calorimetry (DSC. The magnetic properties contained initial and maximum magnetic permeability, coercive force and magnetic after-effects measurements were determined by the Maxwell-Wien bridge and VSM methods.Findings: The X-ray diffraction and transmission electron microscopy investigations revealed that the studied as-cast bulk metallic glasses in form of ribbons and rods were amorphous. Two stage crystallization process was observed for studied bulk amorphous alloy. The differences of crystallization temperature between ribbons and rods with chosen thickness are probably caused by different amorphous structures as a result of the different cooling rates in casting process. The SEM images showed that studied fractures could be classified as mixed fractures with indicated two zones contained “river” and “smooth” areas. The changing of chosen soft magnetic properties (μr, Bs, Hc obtained for samples with different thickness is a result of the non-homogenous amorphous structure of tested metallic glasses. The annealing process in temperature range from 373 to 773 K causes structural relaxation of tested amorphous materials, which leads to changes in their physical properties. The qualitative

  12. F-Alloy: An Alloy Based Model Transformation Language

    OpenAIRE

    Gammaitoni, Loïc; Kelsen, Pierre

    2015-01-01

    Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In this paper we introduce the concept of functional Alloy modules. In essence a functional Alloy module can be viewed as an Alloy module representing a model transformation. We describe a sublanguage of Alloy called F-Alloy that allows the specification of functional Alloy modules. Module...

  13. Laser plasma channel formation in barium vapor based on superelastic heating of electrons

    International Nuclear Information System (INIS)

    Computational study of plasma channel formation kinetics in optically dense barium vapor irradiated by pulsed laser light tuned to the Ba I resonance transition at λ = 553.5 nm has been performed. Seed electrons are produced due to the mechanism of atoms associative ionization, which then gain energy in superelastic collisions and initiate the avalanche ionization of atoms by electron impact. We have studied the influence of radiative transfer effects in cylindrically symmetric gas volume on the excitation kinetics of multilevel barium atoms, dynamics of absorption of laser radiation, and the plasma channel expansion in the form of a halo in condition of competition between the ionizing and quenching electron collisions with excited atoms. (paper)

  14. Passivation of alloys on titanium base

    International Nuclear Information System (INIS)

    Results of passivation studies on Ti-base alloys show that the inhibition of anodic processes on these alloys is determined not by the total thickness of passive film, but by its barrier layer. The protective properties of the barrier layer increase if the passive film is formed at anodic potentials more positive than +1.4V. They were determined not by chemical stability of barrier layer, but by an inhibition which is produced by this layer for ionic current along the anodic direction. The protective properties are related to character defectiveness and semiconductor properties of the barrier layer. Additions of Al, V, Mo, Zr, and Nb to titanium increase the anodic current in the passive state. Additions of Cr and Mn decrease this current, and Sn does not influence it. The direct electrochemical transition of titanium ions into solution (as TiO2+) is a main anodic process of titanium dissolution and its low alloyed alloys in the passive state. Double phase titanium alloys (after tempering) have a lower corrosion resistance than those in the homogeneous single phase state (after hardening). The less passive phase of double phase alloys dissolves perferentially. The less passive phases are: in the active state, α-phase; in transpassive state for Ti--Mo alloys, β-phase, containing in a high Mo percentage; and for Ti--Cr alloys, γ-phase, having more chromium. (U.S.)

  15. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

    Directory of Open Access Journals (Sweden)

    Sukanta Das

    2014-01-01

    Full Text Available In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth.

  16. New barium tantalum sulphides

    International Nuclear Information System (INIS)

    The authors discuss a new barium tantalum sulphide, Ba3Ta2S8, prepared by sulphurization of a mixture of BaCO3 and Ta2O5. The electron and powder X-ray diffraction patterns of the compound are indexed on the basis of a monoclinic cell with lattice constants. A structure model is proposed. The refinement based on the powder X-ray diffraction intensities is performed

  17. LASER CLADDING ON ALUMINIUM BASE ALLOYS

    OpenAIRE

    Pilloz, M.; Pelletier, J; Vannes, A.; Bignonnet, A.

    1991-01-01

    laser cladding is often performed on iron or titanium base alloys. In the present work, this method is employed on aluminum alloys ; nickel or silicon are added by powder injection. Addition of silicon leads to sound surface layers, but with moderated properties, while the presence of nickel induces the formation of hard intermetallic compounds and then to an attractive hardening phenomena ; however a recovery treatment has to be carried out, in order to eliminate porosity in the near surface...

  18. Structural, microstructural and impedance spectroscopy study of functional ferroelectric ceramic materials based on barium titanate

    International Nuclear Information System (INIS)

    The differences between the physical properties of barium titanate BaTiO3 and newly obtained BaHfxTi1-xO3 were identified. These ceramics were prepared by solid-phase reaction from simple oxides and carbonates using the conventional method. The structure and morphology of investigated samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The application of impedance spectroscopy made possible to characterize of these materials in the terms of electrical properties

  19. BARIUM RECOVERY PROCESS

    Science.gov (United States)

    Blanco, R.E.

    1959-07-21

    A method of separating barium from nuclear fission products is described. In accordance with the invention, barium may be recovered from an acidic solution of neutron-irradiated fissionable material by carrying ihe barium cut of solution as a sulfate with lead as a carrier and then dissolving the barium-containing precipitate in an aqueous solution of an aliphatic diamine chelating reagent. The barium values together with certain other metallic values present in the diamine solution are then absorbed onto a cation exchange resin and the barium is selectively eluted from the resin bed with concentrated nitric acid.

  20. Nonlinear photonic crystal waveguide structures based on barium titanate thin films and their optical properties

    Science.gov (United States)

    Liu, Zhifu; Lin, Pao-Tai; Wessels, Bruce W.; Yi, Fei; Ho, Seng-Tiong

    2007-05-01

    Nonlinear photonic crystal waveguide structures were fabricated from barium titanate thin films using nanolithography. A cascaded Bragg reflector using a strip waveguide was designed and analyzed. Both simulation and experimental results show that there is sufficient refractive index contrast to form a stop band by only etching through the Si3N4 strip layer. The band gap of the Bragg reflector can be engineered through control of the Bragg spacing, thickness, and etching depth of the strip layer. The transmission spectrum of the Bragg reflector waveguide was measured over the spectral range of 1500-1580nm. A 27nm wide stop band was obtained for a millimeter long sample. The nonlinear photonic crystal waveguides are potentially suitable as tunable filters, optical switches, and ultrawide bandwidth modulators.

  1. Choice of double contrast barium enema (DCBE) method based on patient exposure dose

    International Nuclear Information System (INIS)

    Morbidity of colon cancer continues to increase, taking second and third places in malignant tumors. The incidence of colorectal cancer (CRC) increases exponentially with age; those over 50 years of age represent 37% of general population, yet account for 95% of the cases, and more than 96% of the deaths from colon malignancies For a long time radiologic examinations were considered as a main pre-operative diagnostic method for cancer of the colon. The sensitivity of the barium enema with regard to diagnosis of the carcinoma and polyps ranges from 92-98.5%. Sigmoidoscopy for detection and removal of polyps has been shown to decrease the incidence of subsequent CRC's by 70-80% in distal colon. However, the sigmoid colon is often difficult to examine because of associated diverticular disease, and about 15% of tumors in the sigmoid colon are overlooked. Authors)

  2. Oxygen diffusion in vanadium-based alloys

    International Nuclear Information System (INIS)

    The experimental study of transport and equilibrium properties of oxygen in vanadium-based alloys was made by EMF measurements on solid electrolytic cells over the temperature range of 873 to 14230K. The oxygen diffusion in vanadium was not significantly modified by small additions of Ti, Cr, Ni, Nb and Ta. The increase in the activation energy for oxygen diffusion in the V-based alloys containing Cr, Ni, Nb and Ta probably reflects the effect of these substitutional solutes on the activity coefficient of oxygen. The oxygen activity was increased by the addition of 1 at % of Cr, Ni and Nb, and decreased by the addition of Ti and Ta. However, the effects in the alloys containing Nb and Ta are very small

  3. Irradiation creep of vanadium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  4. Barium enema (image)

    Science.gov (United States)

    A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...

  5. 21 CFR 872.3710 - Base metal alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  6. Creep of nickel-base alloys in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Fish, J.S.; Attanasio, S.A.; Krasodomski, H.T.; Wilkening, W.W.; Was, G.S.; Cookson, J.; Yi, Y.

    1999-08-01

    Creep tests were performed to compare the creep behavior of commercial nickel-base alloys as a function of stress, temperature, and the environment. The results support earlier work that showed that low carbon alloys are more susceptible to creep and intergranular cracking than are high carbon alloys. Results also show a smaller influence of a water environment on the creep rate of commercial, creep-resistant alloys compared to high purity alloys.

  7. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  8. Ion-beam synthesis and the studies of nanocomposite multiferroics based on barium titanate

    International Nuclear Information System (INIS)

    Co+ and Fe+ ions were implanted into single-crystalline barium titanate (BaTiO3) with fluences of (0.5−1.5)x1017 ion/cm2 to synthesize new multiferroic materials. High-fluence 3d-ion implantation results in the formation of Co (or Fe) nanoparticles with sizes of 5-10 nm in the irradiated layer of BaTiO3. With increasing the fluence both Co- and Fe-implanted BaTiO3 samples reveal at first superparamagnetic, and then ferromagnetic properties at room temperature. The strong shift of ferromagnetic resonance line under dc electric field and magnetocapacitance effects were observed in Co-implanted BaTiO3. These observations are a good evidence of the magnetoelectric coupling in Co-implanted BaTiO3. Our investigations show that ion implantation can be used to synthesize multiferroic composite materials like Co:BaTiO3 and Fe:BaTiO3. (authors)

  9. Planar Millimeter Wave Notch Filters Based on Magnetostatic Wave Resonance in Barium Hexagonal Ferrite Thin Films

    Science.gov (United States)

    Lu, Lei; Song, Young-Yeal; Bevivino, Joshua; Wu, Mingzhong

    2010-10-01

    There is a critical need for planar millimeter (mm) wave devices. To meet this need, one important strategy is in the use of high-anisotropy hexagonal ferrite films. The high internal anisotropy field for the hexagonal ferrites can be used to realize low-loss devices in the 30-100 GHz regime without the need for high external magnetic fields. Previous work has demonstrated the use of M-type barium hexagonal ferrite (BaM) films and ferromagnetic resonance therein to make mm-wave notch filters. This presentation reports on a new mm-wave notch filter that uses magnetostatic wave (MSW) resonance in BaM films. The device consists of a BaM film strip positioned on the top of a coplanar waveguide (CPW), with the strip's length along the CPW signal line. The BaM strip was grown by pulsed laser deposition and had uniaxial anisotropy along the strip's length. The device showed a band-stop filtering response centered at 53 GHz in absence of external fields. One can increase this frequency with nonzero external fields. A reduction in the strip's width resulted in an enhancement in peak absorption. This filtering response resulted from MSW resonance across the BaM strip's width. The MSW modes were excited by CPW-produced non-uniform alternating magnetic fields.

  10. Preparation, characterization, biological activity, and transport study of polystyrene based calcium–barium phosphate composite membrane

    International Nuclear Information System (INIS)

    Calcium–barium phosphate (CBP) composite membrane with 25% polystyrene was prepared by co-precipitation method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Thermogravimetric analysis (TGA) were used to characterize the membrane. The membrane was found to be crystalline in nature with consistent arrangement of particles and no indication of visible cracks. The electrical potentials measured across the composite membrane in contact with univalent electrolytes (KCl, NaCl and LiCl), have been found to increase with decrease in concentrations. Thus the membrane was found to be cation-selective. Transport properties of developed membranes may be utilized for the efficient desalination of saline water and more importantly demineralization process. The antibacterial study of this composite membrane shows good results for killing the disease causing bacteria along with waste water treatment. Highlights: • Transport properties of composite membrane are evaluated. • The composite membrane was found to be stable in all media. • TMS method is used for electrochemical characterization. • The membrane was found to be cation selective. • The order of surface charge density was found to be LiCl < NaCl < KCl

  11. Vanadium-base alloys for fusion reactor applications

    International Nuclear Information System (INIS)

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined

  12. Progress in ODS Alloys: A Synopsis of a 2010 Workshop on Fe- Based ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kad, Bimal [University of California, San Diego; Dryepondt, Sebastien N [ORNL; Jones, Andy R. [University of Liverpool; Vito, Cedro III [National Energy Technology Laboratory (NETL); Tatlock, Gordon J [ORNL; Pint, Bruce A [ORNL; Tortorelli, Peter F [ORNL; Rawls, Patricia A. [National Energy Technology Laboratory (NETL)

    2012-01-01

    In Fall 2010, a workshop on the role and future of Fe-based Oxide Dispersion Strengthened (ODS) alloys gathered together ODS alloy suppliers, potential industrial end-users, and technical experts in relevant areas. Presentations and discussions focused on the current state of development of these alloys, their availability from commercial suppliers, past major evaluations of ODS alloy components in fossil and nuclear energy applications, and the technical and economic issues attendant to commercial use of ODS alloys. Significant progress has been achieved in joining ODS alloys, with creep resistant joints successfully made by inertia welding, friction stir welding and plasma-assisted pulse diffusion bonding, and in improving models for the prediction of lifetime components. New powder and alloy fabrication methods to lower cost or improve endproduct properties were also described. The final open discussion centered on challenges and pathways for further development and large-scale use of ODS alloys.

  13. Discontinuous precipitation in copper base alloys

    Indian Academy of Sciences (India)

    K T Kashyap

    2009-08-01

    Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, , has been calculated and predicted that if 100 > ± 0.1, DP is observed. This criterion points to diffusional coherency strain theory to be the operative mechanism for DP.

  14. Effects of alloying side B on Ti-based AB2 hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    王家淳; 于荣海; 刘庆

    2004-01-01

    Ti-based AB2-type hydrogen storage alloys are a group of promising materials, which will probably replace the prevalent rare earth-based AB5-type alloys and be adopted as the main cathode materials of nickelmetal hydride (Ni-MH) batteries in the near future. Alloying in side B is a major way to improve the performance of Ti-based AB2-type alloys. Based on recent studies, the effects of alloying elements in side B upon the performance of Ti-based AB2 -type hydrogen storage alloys are systematically reviewed here. These performances are divided into two categories, namely PCI characteristics, including hydrogen storage capacity (HSC), plateau pressure (PP), pressure hysteresis (PH) and pressure plateau sloping (PPS) , and electrochemical properties, including discharge capacity (DC), activation property (AP), cycling stability (CS) and high-rate dischargeability (HRD). Furthermore, the existing problems in these investigations and some suggestions for future research are proposed.

  15. Characterization of copper base alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    The micro and nano structure of mechanical alloys of Cu-Al, Cu-V and Cu-Ti obtained by reactive milling, using an Attritor mill, was analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). In order to study the evolution of the alloys during the manufacturing process and during the period of service, the DSC and XRD were done before the mechanical milling, after 30 hours of milling and after hot extrusion of the alloyed powders. Using the Williamson-Hall and Klug-Alexander methods the size of the crystallites and the density of the dislocations in the prepared alloys were evaluated. In all the milled powder cases, the grain and crystallite size was found to be nanometric, the dispersoids were also nanometric and there was texture in the copper planes (220), in the cases of the milled Cu- Ti and Cu-V powders (au)

  16. Radioisotope analyzer of barium

    International Nuclear Information System (INIS)

    Principle of operation and construction of radioisotope barium sulphate analyzer type MZB-2 for fast determination of barium sulphate content in barite ores and enrichment products are described. The gauge equipped with Am-241 and a scintillation detector enables measurement of barium sulphate content in prepared samples of barite ores in the range 60% - 100% with the accuracy of 1%. The gauge is used in laboratories of barite mine and ore processing plant. 2 refs., 2 figs., 1 tab. (author)

  17. Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water

    Science.gov (United States)

    Ota, K.; Conger, W. L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

  18. Simulations of high permittivity materials for 7 T neuroimaging and evaluation of a new barium titanate-based dielectric.

    Science.gov (United States)

    Teeuwisse, W M; Brink, W M; Haines, K N; Webb, A G

    2012-04-01

    High permittivity "dielectric pads" have been shown to increase image quality at high magnetic fields in regions of low radiofrequency transmit efficiency. This article presents a series of electromagnetic simulations to determine the effects of pad size and geometry, relative permittivity value, as well as thickness on the transmit radiofrequency fields for neuroimaging at 7 T. For a 5-mm thick pad, there is virtually no effect on the transmit field for relative permittivity values lower than ∼90. Significant improvements are found for values between 90 and ∼180. If the relative permittivity is increased above ∼180 then areas of very low transmit efficiency are produced. For a 1-cm thick pad, the corresponding numbers are ∼60 and ∼120, respectively. Based upon the findings, a new material (barium titanate, relative permittivity ∼150) is used to produce thin (∼5 mm) dielectric pads which can easily be placed within a standard receive head array. Experimental measurements of transmit sensitivities, as well as acquisition of T(2) - and T 2*-weighted images show the promise of this approach. PMID:22287360

  19. Nature and spatial distribution of sulfur species in a sulfated barium-based commercial lean NOx trap catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae-Soon [ORNL; Partridge Jr, William P [ORNL; Lance, Michael J [ORNL; Walker, Larry R [ORNL; Pihl, Josh A [ORNL; Toops, Todd J [ORNL; FINNEY, Charles E A [ORNL; Daw, C Stuart [ORNL

    2010-01-01

    We report observations of the nature and spatial distribution of sulfur species on a sulfated Ba-based commercial lean NO{sub x} trap (LNT) catalyst. The monolithic catalyst was sulfated in a bench flow reactor during 60/4-s NO{sub x} storage/reduction cycling to achieve a total sulfur loading of 3.4 g L{sup -1} of catalyst. Washcoat composition, structure and sulfur distribution were analyzed with electron probe microanalysis, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed reduction. The most significant washcoat elements of catalytic relevance were Pt, Pd, Rh, Ba, Ce, Zr, Mg, Al, and these were present mainly in four distinct domains; Mg/Al mixed oxide with Pt, Ce; Al oxide with Rh, Pd; Ce/Zr mixed oxide with Pt, Pd, Ba (high Ba content); Ce/Zr mixed oxide with Pt, Pd, Ba (lower Ba content). Sulfur was present in the form of sulfates that decreased in concentration along the LNT axis from front to back. Barium showed the highest sulfur affinity leading to a plug-like axial progression of its sulfation. The sulfation of AI, Mg/Al, and Ce/Zr oxides was less vigorous with a more axially dispersed and less penetrating front.

  20. Ti-V-Mn based alloys for hydrogen compression system

    Energy Technology Data Exchange (ETDEWEB)

    Dehouche, Z. [Institut de Recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Que., G9A 5H7 (Canada)]. E-mail: zahir_dehouche@uqtr.ca; Savard, M. [Institut de Recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Que., G9A 5H7 (Canada); Laurencelle, F. [Institut de Recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Que., G9A 5H7 (Canada); Goyette, J. [Institut de Recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Que., G9A 5H7 (Canada)

    2005-09-01

    Ti-V-Mn based hydrides are one family of alloys with improved hydrogenation properties and they have a great potential to replace the AB{sub 5} alloys as the sorption materials in hydrogen compression systems, although there still are many problems associated with their use, including unstable reversible hydrogen capacity and unfavorable thermodynamic properties. To gain a better understanding on the effect of the substitution elements and to optimize the alloy composition for high storage capacity, the influence of the alloy stoichiometry was investigated. Ti-Zr-V-Mn alloys were prepared by arc melting technique and were annealed in vacuum at temperature above 900 deg. C to obtain great sorption properties. Hydrogen absorption and desorption kinetics and PCT characteristics of these alloys at ambient temperature were measured and compared. These hydrogen storage features were also discussed in relation to the effect of alloy element compositions. Ti-Zr-V-Mn alloy cycling behavior was also examined.

  1. Ti-V-Mn based alloys for hydrogen compression system

    International Nuclear Information System (INIS)

    Ti-V-Mn based hydrides are one family of alloys with improved hydrogenation properties and they have a great potential to replace the AB5 alloys as the sorption materials in hydrogen compression systems, although there still are many problems associated with their use, including unstable reversible hydrogen capacity and unfavorable thermodynamic properties. To gain a better understanding on the effect of the substitution elements and to optimize the alloy composition for high storage capacity, the influence of the alloy stoichiometry was investigated. Ti-Zr-V-Mn alloys were prepared by arc melting technique and were annealed in vacuum at temperature above 900 deg. C to obtain great sorption properties. Hydrogen absorption and desorption kinetics and PCT characteristics of these alloys at ambient temperature were measured and compared. These hydrogen storage features were also discussed in relation to the effect of alloy element compositions. Ti-Zr-V-Mn alloy cycling behavior was also examined

  2. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    International Nuclear Information System (INIS)

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound

  3. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.P. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Duarte, G.W. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Research Group in Technology and Information, Centro Universitário Barriga Verde (UNIBAVE), Santa Catarina, SC (Brazil); Caldart, C. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Kniess, C.T. [Post-Graduate Program in Professional Master in Management, Universidade Nove de Julho, São Paulo, SP (Brazil); Montedo, O.R.K.; Rocha, M.R. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Riella, H.G. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduate Program in Environmental Science, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil); Post-Graduate Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil)

    2015-11-15

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound.

  4. Microstructures of nickel-base alloy dissimilar metal welds

    OpenAIRE

    Mouginot, Roman; Hänninen, Hannu

    2013-01-01

    Dissimilar metal welds (DMWs) between low-alloy steels (LAS), stainless steels (SS) and nickel-base alloys are very important in the design of conventional and nuclear power plants (NPPs). They help to reach better performances for high temperature environment but they can promote premature failure of components. Failure is often related to cracking in the heat affected zone of base materials. In this study, a literature review was conducted concerning the behavior of Inconel Ni-base alloy...

  5. Indentation toughness of Mo5Si3-based alloys

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The indentation toughness of Mo5Si3 -based phases was studied with regard to different alloying elements, amount of alloying addition as well as the presence of secondary phases. Cr, Ti, Nb, Ni and Co were added as alloying elements. The results show that the indentation fracture toughness of Mo5Si3 increases with the alloying additions, from 2.4 Mpa *m1/2 for mon olithic to just over 3 Mpa*m1/2 for highly alloyed Mo5Si3. Small volume fractions of brittle secondary phases may have a positive impact on the inde ntation toughness; while larger fractions seems to lower the toughness.

  6. Stress corrosion crack tip microstructure in nickel-based alloys

    International Nuclear Information System (INIS)

    Stress corrosion cracking behavior of several nickel-base alloys in high temperature caustic environments has been evaluated. The crack tip and fracture surfaces were examined using Auger/ESCA and Analytical Electron Microscopy (AEM) to determine the near crack tip microstructure and microchemistry. Results showed formation of chromium-rich oxides at or near the crack tip and nickel-rich de-alloying layers away from the crack tip. The stress corrosion resistance of different nickel-base alloys in caustic may be explained by the preferential oxidation and dissolution of different alloying elements at the crack tip. Alloy 600 (UNS N06600) shows good general corrosion and intergranular attack resistance in caustic because of its high nickel content. Thermally treated Alloy 690 (UNS N06690) and Alloy 600 provide good stress corrosion cracking resistance because of high chromium contents along grain boundaries. Alloy 625 (UNS N06625) does not show as good stress corrosion cracking resistance as Alloy 690 or Alloy 600 because of its high molybdenum content

  7. Thermal sprayed iron base alloys coatings

    International Nuclear Information System (INIS)

    Particularities of thermal spraying of iron-based alloys coatings are associated with sufficiently great values of parameter of melting difficulty (for Fe D = 2.08 I-10/sup 10/ kJ.kg/sup -1/.m/sup -3/), and relatively low values of coefficients-of heat accumulation (for Fe b=C.raw.Lambda /sub 0.5/=108 W.m/sup -2/.K.sec/sup-0.5/). These materials are less inclined to form quality coating under the influence of the thermal activation and therefore it is reasonable to use in addition the mechanical activation of substrate surface. The powder of iron-base alloy FeSi/sub 7/AI/sub 3.5/C/sub 2/ was obtained by melt-atomization with water hardening of droplets. The main phase components of powder are alpha and gamma -solid solution on base of Fe (austenite), cementite (Fe/sub 3/C), metastable rhombic lattice x-phase, and possibly metastable carbide Fe/sub 2/C. When the powder particles shape is oval which axis dimensions about 80 and 300 micro meter, the main phase components of detonation sprayed coatings in case of oxy-acetylene gas mixture are alpha and gamma -phases, in case of oxy-propane-butane mixture the coating phase component the same as initial powder. When the powder particles size is 63-100 micro meter, the coatings phase components are alpha and gamma - solid solutions, Fe/sub 3/C, x-phase, Fe/sub 2/C, Fe/sub 3/0/sub 4/ and FeO. The main phase components of FeSi/sub 7/B/sub 12,6/ powder are alpha-solid solution, borides Fe/sub 2/B and FeB, X- phase. The sprayed coatings have the same phase composition. These types of Fe-base alloys powders have relatively low cost, easy available and can used for deposition of wear resistant coatings. (author)

  8. ATOM PROBE STUDY OF TITANIUM BASE ALLOYS : PRELIMINARY RESULTS

    OpenAIRE

    Menand, A.; Chambreland, S.; Martin, C

    1986-01-01

    Two different titanium base alloys, Ti46 Al54 and Ti88.8 Cu2.3, Al8.9, have been studied by atom probe microanalysis. A precipitate of Ti2 Al was analysed in the binary alloys. Micro-analysis of Ti Cu Al alloy revealed the presence of Copper enriched zones. The study has also exhibited a penetration of Hydrogen in the samples, probably due to preparation technique. The results demonstrate the feasibility of studies on titanium base alloys by mean of atom probe.

  9. Hot rolling of intermetallics FeAl phase based alloys

    OpenAIRE

    G. Niewielski; D. Kuc; Schindler, I.; I. Bednarczyk

    2008-01-01

    Purpose: The one of major problem restricting universal employment of intermetallic phase base alloy istheir low plasticity which leads to hampering their development as construction materials. The following workconcentrates on possibilities to form through rolling process the alloys with various aluminium content.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axialsymmetriccompression at temperatures ranging from 900 to 1200°C at 10 s-1 strain rat...

  10. Tailored Barium Swallow Study

    Science.gov (United States)

    ... View Denver Pollen Count You are here: Programs & Services > Tests We Offer > Imaging Tests Tailored Barium Swallow Study The TBS is a special study that is completed in radiology. The test evaluates the mouth and the throat ...

  11. Cyclodextrin-grafted barium titanate nanoparticles for improved dispersion and stabilization in water-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Serra-Gómez, R. [Universidad de Navarra, Departamento de Química y Edafología (Spain); Martinez-Tarifa, J. M. [Universidad Carlos III de Madrid, Departamento de Ingeniería Eléctrica (Spain); González-Benito, J. [Universidad Carlos III de Madrid, Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IQMAAB (Spain); González-Gaitano, G., E-mail: gaitano@unav.es [Universidad de Navarra, Departamento de Química y Edafología (Spain)

    2016-01-15

    preparation of the water-based nanocomposites either as hydrogels or as nanocomposites based on thermoplastic matrices.

  12. Cyclodextrin-grafted barium titanate nanoparticles for improved dispersion and stabilization in water-based systems

    International Nuclear Information System (INIS)

    of the water-based nanocomposites either as hydrogels or as nanocomposites based on thermoplastic matrices.

  13. Molecular structures of (3-aminopropyl)trialkoxysilane on hydroxylated barium titanate nanoparticle surfaces induced by different solvents and their effect on electrical properties of barium titanate based polymer nanocomposites

    Science.gov (United States)

    Fan, Yanyan; Wang, Guanyao; Huang, Xingyi; Bu, Jing; Sun, Xiaojin; Jiang, Pingkai

    2016-02-01

    Surface modification of nanoparticles by grafting silane coupling agents has proven to be a significant approach to improve the interfacial compatibility between inorganic filler and polymer matrix. However, the impact of grafted silane molecular structure after the nanoparticle surface modification, induced by the utilized solvents and the silane alkoxy groups, on the electrical properties of the corresponding nanocomposites, has been seldom investigated. Herein, the silanization on the surface of hydroxylated barium titanate (BT-OH) nanoparticles was introduced by using two kinds of trialkoxysilane, 3-aminopropyltriethoxysilane (AMEO) and 3-aminopropyltrimethoxysilane (AMMO), with different solvents (toluene and ethanol), respectively. Solid-state 13C, 29Si nuclear magnetic resonance (NMR) spectroscopy and high-resolution X-ray photoelectron spectroscopy (XPS) were employed to validate the structure differences of alkoxysilane attachment to the nanoparticles. The effect of alkoxysilane structure attached to the nanoparticle surface on the dielectric properties of the BT based poly(vinylidene fluoride) (PVDF) nanocomposites were investigated. The results reveal that the solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. Nevertheless, the alkoxy groups of silane show a marginal influence on the dielectric properties of the nanocomposites. These research results provide important insights into the fabrication of advanced polymer nanocomposites for dielectric applications.

  14. Planar millimeter wave band-stop filters based on the excitation of confined magnetostatic waves in barium hexagonal ferrite thin film strips

    Science.gov (United States)

    Lu, Lei; Song, Young-Yeal; Bevivino, Joshua; Wu, Mingzhong

    2011-05-01

    A planar millimeter wave band-stop filter based on confined magnetostatic wave (MSW) excitations in an M-type barium hexagonal ferrite (BaM) film strip was demonstrated. The device consists of a BaM film strip on the top of a coplanar waveguide with the strip length along the signal line. For zero magnetic fields, the device shows a band-stop filtering response at 53 GHz. This response originates from the excitation of confined MSW modes across the BaM strip width. The filter operation frequency is tunable with low fields. This tuning relies on the change in the MSW dispersion with field.

  15. Microwave absorption properties of double-layer absorber based on carbonyl iron/barium hexaferrite composites

    Science.gov (United States)

    Ren, Xiaohu; Fan, Huiqing; Cheng, Yankui

    2016-05-01

    The microwave absorption properties of BaCo0.4Zn1.6Fe16O27 ferrite and carbonyl iron powder with single-layer and double-layer composite absorbers were investigated based on the electromagnetic transmission line theory in the frequency range from 1 to 14 GHz. XRD was used to characterize the structure of prepared absorbing particles. SEM was used to examine the micromorphology of the particles and composites. The complex permittivity and permeability of composites were measured by using a vector network analyzer. The reflection loss of the single-layer and double-layer absorbers with different thicknesses and orders was investigated. The results show that double-layer absorbers have better microwave absorption properties than single-layer absorbers. The microwave absorption properties of the double-layer structure are influenced by the coupling interactions between the matching and absorption layers. As the pure ferrite used as matching layer and the composite of BF-5CI used as absorption, the minimum RL of absorber can achieve to -55.4 dB and the bandwidth of RL <-10 dB ranged from 5.6 to 10.8 GHz when the thicknesses of matching layer and absorption layer were 0.9 and 1.4 mm, respectively.

  16. Characterization of internal boundary layer capacitors based upon barium titanate and strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Duk

    1981-01-01

    The nature of ceramic microstructure and the electrical properties of individual grains and junctions was determined by STEM, microprobe analysis and microscale electrical measurements. The chemical compositions of the resistive boundary regions were different from those of the grains. Additives were concentrated in the boundary regions, forming resistive layers. Limited diffusion of the counterdopants into the grain subsurface formed an interfacial compensation layer between the insulating intergranular layer and the semiconducting grains. The electrical behavior of this intermediate layer was found to be similar to that of a depletion layer. Ceramic microstructures were approximated by a three-layer n-c-i-c-n model and representive equivalent circuit, which was used to explain the voltage dependence of the dielectric constant and dispersion behavior. Calculated properties were in good agreement with experimental values. Fine grain microstructures developed by liquid phase sintering techniques, were suitable for high dielectric constant multilayer capacitors, based upon internal boundary layer phenomena, and these capacitors had stable dielectric characteristics.

  17. Plasticizer Effect on Rheological Behaviour of Screen Printing Pastes Based on Barium Titanate Nanopowder

    Science.gov (United States)

    Dulina, I.; Umerova, S.; Ragulya, A.

    2015-04-01

    The dependence of rheological behaviour of pastes based on BaTiO3 nanopowder vs. plasticizer content has been investigated. All pastes prepared for research can be divided into groups by structure types and viscosity. Such a grouping has been explained by different interaction between nanoparticles and binder in the pastes. Particles with molecules of binder form clusters - the representative units in the volume of paste where particles are uniformly distributed. Plasticizer adding effects on binder molecule conformation and change clusters size. Bond strength between clusters can be specified with rheopexy in the area of low shear stress and low strain rates. Rheopexy degree increasing authenticates interaction intensification between clusters. Rheopexy structure destruction leads to separate clusters formation and initiation of the pseudoplastic flow stage. The end of pseudoplastic flow corresponds to structure with clusters assembled into separated layers. Further shear stress increasing leads to inter-clusters bonds appear which can be deformed elastically and the temporary local linkage is possible. Such a phenomenon fully discloses the features of thixotropic structure destruction in plasticized pastes.

  18. Barium-137 M milkers based on 12-molybdo cerate column matrix. Vol. 3

    International Nuclear Information System (INIS)

    The interaction of 134 Cs+ and 131,133 Ba2+ radiotracers (10-4 M for each) in HCl, H N O3, Na Cl, Na N O3, and N H4 Cl solutions on 12-Molybdo cerate (IV) has been studied by batch equilibrium at room temperature. The corresponding distribution coefficients (Kd values in mi/g) were determined as a function of the composition of the reaction medium and drying temperature; 50, 150 and 200 degree C of the molybdate matrix under comparable conditions, Cs+ ions are strongly retained on the adsorbent material than Ba2+ ions. Elution performance of the daughter 134m Ba (T1/2=2.7 min.) from its parent 137 Cs (T1/2=30 y) was investigated on small chromatographic columns of the matrix. Based on the data obtained, 2 g 12-molybdo cerate (IV), dried at 200 degree C, loaded with 1 mCi 137 Cs/137m Ba milkers was prepared. The generated 137m Ba daughter was continuously eluted by passing a mixture solution of 0.1 M HCl + 0.1 M N H4 Cl as eluent through the column bed at flow rates of 1 and 2 m1/min. Eluate assessment proved reproducibility of the elution yields about 58% 137m Ba in 5 m1 eluate. Radionuclidic and chemical purity of the eluate proved to be suitable for use in nuclear medicine and also industrial applications. 6 figs., 1 tab

  19. HIGH CYCLE FATIGUE PROPERTIES OF NICKEL-BASE ALLOY 718

    Institute of Scientific and Technical Information of China (English)

    K.Kobayashi; K.Yamaguchi; M.Hayakawa; M.Kimura

    2004-01-01

    The fatigue properties of nickel-base Alloy 718 with fine- and grain-coarse grains were investigated. In the fine-grain alloy, the fatigue strength normalized by the tensile strengtn was 0.51 at 107 cycles. In contrast, the fatigue strength of the coarse-grain alloy was 0.32 at the same cycles, although the fatigue strengths in the range from 103to 105 cycles are the same for both alloys. The fracture appearances fatigued at around 106 cycles showed internal fractures originating from the flat facets of austenite grains for both alloys. The difference in fatigue strength at 107 cycles between the fine- and coarse-grain alloys could be explained in terms of the sizes of the facets from which the fractures originated.

  20. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  1. Structural Characteristics & Dielectric Properties of Tantalum Oxide Doped Barium Titanate Based Materials

    Directory of Open Access Journals (Sweden)

    Rubayyat Mahbub

    2012-11-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mol% Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90% was achieved for 0.5 and 1.0 mol% Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0·5 mol% Ta2O5. Although fine grain size down to 200-300nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000-14000 was found in the temperature range of  55 to 80°C, for 1.0 mol% Ta2O5 doped samples with corresponding shift of Curie point to ~82°C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  2. STRUCTURAL CHARACTERISTICS & DIELECTRIC PROPERTIES OF TANTALUM OXIDE DOPED BARIUM TITANATE BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Md. Fakhrul Islam

    2013-01-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mole % Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90 % was achieved for 0.5 and 1.0 mole %Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0.5 mole % Ta2O5. Although fine grain size down to 200 - 300 nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000 - 14000 was found in the temperature range of 55 to 80 °C, for 1.0 mole % Ta2O5 doped samples with corresponding shift of Curie point to ~82 °C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  3. LASER CLADDING WITH COBALT-BASED HARDFACING ALLOYS

    OpenAIRE

    Frenk, A.; WagniÈre, J.-D.

    1991-01-01

    Preliminary results aimed at designing Co-based hardfacing alloys specifically for the laser cladding process are reported. Three alloys, ranging from hypo- to hypereutectic were deposited using scanning velocities between 1.7 and 170 mm/s. The microstructures and the dry sliding wear resistances of the clads were investigated. First trends relating composition to dry sliding wear resistance were deduced.

  4. Corrosion resistance improvement of titanium base alloys

    Directory of Open Access Journals (Sweden)

    Mihai V. Popa

    2010-01-01

    Full Text Available The corrosion resistance of the new Ti-6Al-4V-1Zr alloy in comparison with ternary Ti-6Al-4V alloy in Ringer-Brown solution and artificial Carter-Brugirard saliva of different pH values was studied. In Ringer-Brown solution, the new alloy presented an improvement of all electrochemical parameters due to the alloying with Zr; also, impedance spectra revealed better protective properties of its passive layer. In Carter-Brugirard artificial saliva, an increase of the passive film thickness was proved. Fluoride ions had a slight negative influence on the corrosion and ion release rates, without to affect the very good stability of the new Ti-6Al-4V-1Zr alloy.

  5. Fabrication and characterization of niobium based Fe-Cr alloys via mechanical alloying

    International Nuclear Information System (INIS)

    Niobium (Nb) based alloys and composites are currently used in various high temperature applications such as rocket engine nozzles, superconducting magnets, and automotive structural components. Niobium has also been traditionally employed as a micro-alloying element to fabricate high strength, low alloy steels and nickel based superalloys (example: Inconel 718) on account of its ability to form nano dispersions/precipitates which effectively impede high temperature grain growth. Traditionally, niobium alloys such as C-103 (Nb-10Hf-1Ti) and FS-85 (Nb-10W-28Ta-1Zr) having excellent high temperature properties have been fabricated using arc melting and e-beam melting methods. However these alloys have not been widely used on account of their high fabrication costs. On the other hand, nanostructured steels such as oxide dispersion strengthened (ODS) alloys (example: 12Y1, 12YWT, FeCrAl, HT-9, Hestalloy etc) are being proposed for high temperature structural applications for new generation nuclear reactors. In this context we present some of the work related to fabrication and characterization of some known ODS steel compositions with Nb as a micro-alloying element that is currently underway at the High Temperature Materials Laboratory at Virginia Commonwealth University in context of high temperature nuclear applications. (author)

  6. Processing TiAl-Based Alloy by Elemental Powder Metallurgy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    TiAl-based alloys with various compositions (including Ti-48Al, Ti-47Al-2Cr-2Nb, Ti-47Al-2Cr-2Nb-0.2B and Ti-47Al-3Cr, in mole fraction) had been prepared by elemental powder metallurgy (EPM). The results have shown that the density of the prepared Ti-48Al alloy increases with increasing hot pressing temperature up to 1300℃. The Ti-48Al alloy microstructure mainly consisted of island-like Ti3Al phase and TiAl matrix at hot pressing temperature below 1300℃, however, coarse α2/γlamellar colonies and γ grains appeared at 1400℃. It has also indicated that the additions of elemental Cr and B can refine the alloy microstructure. The main microstructural inhomogeneity in EPM TiAl-based alloys was the island-like α2 phase or the aggregate of α2/γ lamellar colony, and such island-like structure will be inherited during subsequent heat treatment in (α+γ) field. Only after heat treatment in α field would this structure be eliminated. The mechanical properties of EPM TiAl-based alloys with various compositions were tested, and the effect of alloy elements on the mechanical properties was closely related to that of alloy elements on the alloy microstructures. Based on the above results, TiAl-based alloy exhaust valves were fabricated by elemental powder metallurgy and diffusion joining. The automobile engine test had demonstrated that the performance of the manufactured valves was very promising for engine service.

  7. Stress corrosion cracking of nickel-base alloy weldments

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of weldments occurs in media such as chloride, hydrofluoric acid, polythionic acid, caustic soda and molten metals. Nickel-base alloys on account of their low SCC are preferred for weldments in the above media. However, the choice of a particular nickel-base alloy depends upon the condition in which they are used. Studies on this aspect are reviewed. In reprocessing plants, Ni-Cr-Mo alloy No6625 and No6455 are found suitable. The Ni-Cr alloy No6600 failed in BWR type reactor due intergranular SCC. The alloy No6690 which has a higher chromium content is immune to intergranular SCC. Reduction of free carbon in the matrix of the weld metal makes it resistant to intergranular SCC. (M.G.B.)

  8. Chemical abundances and kinematics of barium stars

    Science.gov (United States)

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Silva, J. V. Sales

    2016-04-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, alpha-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of alpha-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anti-correlated with the metallicity. Our kinematical analysis showed that 90% of the barium stars belong to the thin disk population. Based on their luminosities, none of the barium stars are luminous enough to be an AGB star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  9. Chemical abundances and kinematics of barium stars

    Science.gov (United States)

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Sales Silva, J. V.

    2016-07-01

    In this paper, we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scaleheight, radial velocities, abundances of the Na, Al, α-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars cannot be represented by a single Gaussian distribution. The abundances of α-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anticorrelated with the metallicity. Our kinematical analysis showed that 90 per cent of the barium stars belong to the thin disc population. Based on their luminosities, none of the barium stars are luminous enough to be an asymptotic giant branch star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  10. Corrosion and wear protective composition modulated alloy coatings based on ternary Ni-P-X alloys

    DEFF Research Database (Denmark)

    Leisner, P.; Benzon, M. E.; Christoffersen, Lasse; Panagopoulos, C. N.; Papachristos, V. D.; Katsikis, S.

    Scattered reporting in the litterature describes a number of ternary Ni-P-X alloyes (where X can be Co, Cr, Cu, Mo, Pd, Re or W) with promising corrosin and wear protective performance. Based on a systematic study of Ni-P-X alloys it is the intention to produce coatings with improved corrosion and...... wear performance compared with conventional coatings like electroless nickel, hard chromioum and anodised aluminium....

  11. Microstructure of polymer composite with barium ferrite powder

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2008-12-01

    Full Text Available Purpose: The aim of the paper is the microstructure characterization of commercial BaFe12O19 powder and its composite material in polymer matrix; XRD (X-Ray Diffraction and SEM (Scanning Electron Microscopy methods were applied.Design/methodology/approach: The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The morphology of barium ferrite powders and a fracture surface of the examined composite material was analyzed using the scanning electron microscope.Findings: The X-ray diffraction analysis enabled the identification of BaFe12O19 and Fe2O3 phases in examined material. Basing on Rietveld and Toraya methods the determination of lattice parameters, crystallite size and the lattice distortion was performed. Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles are of irregular shapes and different sizes.Research limitations/implications: Maked researches are limited only to characterization the microstructure of commercial material, because obtained results will be helpful to prepare barium ferrite powders by mechanical alloying and subsequent annealing in the future. As prepared BaFe12O19 powders will be used as the starting material for magnets bonded with polymer material.Originality/value: The obtained results of investigations by different methods of structure analysis confirm their useful in the microstructure analysis of powder materials.

  12. Lower GI Series (Barium Enema)

    Science.gov (United States)

    ... barium into a bedpan or nearby toilet. A health care professional may give you an enema to flush out the rest of the barium. An x-ray technician and a radiologist perform a lower gastrointestinal (GI) series at a ...

  13. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A. [Oak Ridge National Lab., TN (United States)] [and others

    1996-08-01

    Alloys of Cr-Cr{sub 2}Nb with exceptionally high strength at 1200{degrees}C have been developed. However, these compositions suffer from limited ductility and toughness at room temperature. Despite improvements from processing modifications, as-fabricated defects still limit room temperature mechanical behavior. In contrast, an alloy system with only a small mismatch of the coefficients of thermal expansion of the two phases, Cr-Cr{sub 2}Zr, showed good fabricability. However, these alloys are weaker than Cr-Cr{sub 2}Nb compositions at high temperatures and have poor oxidation resistance. Silicide coatings can provide high-temperature oxidation and sulfidation protection of these alloys. Improvements in room temperature mechanical properties of Laves-phase-strengthened alloys will rely on further development based on increasing the ductility of the matrix phase by impurity control and compositional modifications.

  14. Observed Barium Emission Rates

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  15. On the mechanical properties of TiNb based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. [SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France); Georgarakis, K. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France); Yokoyama, Y. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); Yavari, A.R., E-mail: euronano@minatec.inpg.fr [SIMAP-CNRS, Institut Polytechnique de Grenoble, BP 75, St. Martin d’Hères 38402 (France)

    2013-09-15

    Highlights: •Systematic study of compressive behaviors of TiNb based alloys in different states. •Comparison between X-ray diffraction results in reflection and transmission mode. •High melting temperature TiNb based alloys were fabricated by copper mold casting. •Textures of studied alloys are analyzed through synchrotron radiation data. -- Abstract: A series of TiNb(Sn) alloys were synthesized by copper mold suction casting and subjected to different heat treatments (furnace cooling or water quenching). The microstructure, thermal and mechanical properties of the as-cast and heat treated samples were investigated. For the Ti–8.34 at.% Nb alloy, the as-cast and water quenched samples possess martensitic α′′ phase at room temperature and compression tests of these samples show occurrence of shape memory effect. For β phase Ti–25.57 at.% Nb alloys, stress-induced martensitic transformation was found during compression in the as-cast and water quenched samples. For the ternary Ti–25.05 at.%Nb–2.04 at.%Sn alloy, conventional linear elastic behavior was observed. It is shown that the addition of Sn increases the stability of the β phase. The Young’s moduli of these alloys were also measured by ultrasonic measurements. Water-quenched Ti–25.57 at.%Nb alloy was found to exhibit the lowest Young’s modulus value. Sn addition has small impact on the Young’s moduli of the TiNb alloys.

  16. Development of Mg-based Hydrogen Storage Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail,we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature,especially the substitution of a more electronegative element, such as Al and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature, but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. In order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently,MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.

  17. Nonlinear Hamiltonian modelling of magnetic shape memory alloy based actuators.

    OpenAIRE

    Gauthier, Jean-Yves; Hubert, Arnaud; Abadie, Joël; Chaillet, Nicolas; Lexcellent, Christian

    2008-01-01

    This paper proposes an application of the Lagrangian formalism and its Hamiltonian extension to design, model and control a mechatronic system using Magnetic Shape Memory Alloys. In this aim, an original dynamical modelling of a Magnetic Shape Memory Alloy based actuator is presented. Energy-based techniques are used to obtain a coherent modelling of the magnetical, mechanical and thermodynamic phenomena. The Lagrangian formalism, well suited in such a case, is introduced and used to take int...

  18. Microstructures and oxidation behavior of some Molybdenum based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Pratik Kumar [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that melt in the 1250 - 1450 C, resulting in softening of the alloys above 1000 C. Therefore, recent research directions have been skewed towards exploring and developing newer alloy systems. This thesis comprises a part of such an effort. Techniques for rapid thermodynamic assessments were developed and applied to two different systems - Mo-Si alloys with transition metal substitutions (and this forms the first part of the thesis) and Ni-Al alloys with added components for providing high temperature strength and ductility. A hierarchical approach towards alloy design indicated the Mo-Ni-Al system as a prospective candidate for high temperature applications. Investigations on microstructures and oxidation behavior, under both isothermal and cyclic conditions, of these alloys constitute the second part of this thesis. It was seen that refractory metal systems show a marked microstructure dependence of oxidation.

  19. A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

    Science.gov (United States)

    de Sena, Rodrigo Caciano; Soares, Matheus; Pereira, Maria Luiza Oliveira; da Silva, Rogério Cruz Domingues; do Rosário, Francisca Ferreira; da Silva, Joao Francisco Cajaiba

    2011-01-01

    The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds. PMID:22346607

  20. A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

    Directory of Open Access Journals (Sweden)

    Joao Francisco Cajaiba da Silva

    2011-01-01

    Full Text Available The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds.

  1. A Computationally Based Approach to Homogenizing Advanced Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jablonski, P D; Cowen, C J

    2011-02-27

    We have developed a computationally based approach to optimizing the homogenization heat treatment of complex alloys. The Scheil module within the Thermo-Calc software is used to predict the as-cast segregation present within alloys, and DICTRA (Diffusion Controlled TRAnsformations) is used to model the homogenization kinetics as a function of time, temperature and microstructural scale. We will discuss this approach as it is applied to both Ni based superalloys as well as the more complex (computationally) case of alloys that solidify with more than one matrix phase as a result of segregation. Such is the case typically observed in martensitic steels. With these alloys it is doubly important to homogenize them correctly, especially at the laboratory scale, since they are austenitic at high temperature and thus constituent elements will diffuse slowly. The computationally designed heat treatment and the subsequent verification real castings are presented.

  2. The shape memory effect in systems Cu-based alloys

    OpenAIRE

    2013-01-01

    330a The aim of this work was to analyse the mechanisms of hindered internal passivation of silver based alloys which was obtained by the modification of basic chemical composition. A generalisation of the phenomenon, experimental verification and the estimated range of micro-element concentration is also introduced. The ability for inoculation of a particular alloy is determined by the differences between the formation energies of oxides, as well as their crystallographic similarity. Therefo...

  3. Incorporation of Refractory Metals into Niobium Base Alloys

    OpenAIRE

    Antoni-Zdziobek, A.; Driole, J.; Durand, F; Durand, Franck

    1995-01-01

    Niobium-based alloys with additions such as Al, Ti and Mo were prepared in an inductive cold crucible. A process route was established to provide homogeneous ingots. Key ideas concerning the application of inductive cold crucible to preparation of refractory alloys are brought out. A model is proposed to explain and quantify the experimental observations, which couples the diffusive and convective heat transfers and the heat of mixing involved.

  4. Stabilized nanocrystalline iron-based alloys: Guiding efforts in alloy selection

    International Nuclear Information System (INIS)

    Highlights: → A regular solution model for solute segregation is capable of estimating the effect of solutes on the stability of nanocrystalline Fe. → Stability increases for solutes having larger heats of segregation. → Zr and Ta had an effect on stabilizing the nanocrystalline microstructure of Fe, while Cr and Ni did not. - Abstract: Using a modified regular solution model for grain boundary solute segregation, the relative thermal stability of a number of Fe-based nanocrystalline binary alloys was predicted with considerable accuracy. It was found that nanocrystalline iron was strongly stabilized by zirconium, moderately stabilized by tantalum, and not significantly stabilized by nickel or chromium. These findings are fully in line with the aforementioned predictions. This success with iron based alloys highlights the utility of this practical approach to selecting stabilizing solutes for nanocrystalline alloys.

  5. Processing science of barium titanate

    Science.gov (United States)

    Aygun, Seymen Murat

    Barium titanate and barium strontium titanate thin films were deposited on base metal foils via chemical solution deposition and radio frequency magnetron sputtering. The films were processed at elevated temperatures for densification and crystallization. Two unifying research goals underpin all experiments: (1) To improve our fundamental understanding of complex oxide processing science, and (2) to translate those improvements into materials with superior structural and electrical properties. The relationships linking dielectric response, grain size, and thermal budget for sputtered barium strontium titanate were illustrated. (Ba 0.6Sr0.4)TiO3 films were sputtered on nickel foils at temperatures ranging between 100-400°C. After the top electrode deposition, the films were co-fired at 900°C for densification and crystallization. The dielectric properties were observed to improve with increasing sputter temperature reaching a permittivity of 1800, a tunability of 10:1, and a loss tangent of less than 0.015 for the sample sputtered at 400°C. The data can be understood using a brick wall model incorporating a high permittivity grain interior with low permittivity grain boundary. However, this high permittivity value was achieved at a grain size of 80 nm, which is typically associated with strong suppression of the dielectric response. These results clearly show that conventional models that parameterize permittivity with crystal diameter or film thickness alone are insufficiently sophisticated. Better models are needed that incorporate the influence of microstructure and crystal structure. This thesis next explores the ability to tune microstructure and properties of chemically solution deposited BaTiO3 thin films by modulation of heat treatment thermal profiles and firing atmosphere composition. Barium titanate films were deposited on copper foils using hybrid-chelate chemistries. An in-situ gas analysis process was developed to probe the organic removal and the

  6. Effect of Annealing on Rare Earth Based Hydrogen Storage Alloys

    Institute of Scientific and Technical Information of China (English)

    Li Jinhua

    2004-01-01

    Rare earth-based hydrogen storage alloy used as negative electrode materials for nickel-metal hydride (Ni-MH) batteries are used commercially.The effect of annealing treatment with different annealing temperature and time on the MLNi3.68 Co0.78 Mn0.35 Al0.27 and MMNi3.55 Co0.75 Mn0.40 Al0.30 alloys were investigated.The crystal microstructure,pressure-composition-isotherms (p-C-T) and electrochemical properties of alloys were examined by X-ray diffraction (XRD), automatic PCI monitoring system and electrical performance testing instruments.The optimum annealing treatment conditions of two kinds of alloys were determined.

  7. Characterization of the microstructure in Mg based alloy

    KAUST Repository

    Kutbee, Arwa T

    2013-06-01

    The cast products Mg–Sn based alloys are promising candidates for automobile industries, since they provide a cheap yet thermally stable alternative to existing alloys. One drawback of the Mg–Sn based alloys is their insufficient hardness. The hardenability can be improved by engineering the microstructure through additions of Zn to the base alloy and selective aging conditions. Therefore, detailed knowledge about the microstructural characteristics and the role of Zn to promote precipitation hardening is essential for age hardenable Mg-based alloys. In this work, microstructural investigation of the Mg–1.4Sn–1.3Zn–0.1Mn (at.%) precipitation system was performed using TEM. The chemical composition of the precipitates was analyzed using EDS. APT was employed to obtain precise chemical information on the distribution of Zn in the microstructure. It was found from microstructural studies that different precipitates with varying sizes and phases were present; lath-shaped precipitates of the Mg2Sn phase have an incoherent interface with the matrix, unlike the lath-shaped MgZn2 precipitates. Furthermore, nano-sized precipitates dispersed in the microstructure with short-lath morphology can either be enriched with Sn or Zn. On the other hand, APT analysis revealed the strong repulsion between Sn and Zn atoms in a portion of the analysis volume. However, larger reconstruction volume required to identify the role of Zn is still limited to the optimization of specimen preparation.

  8. Molten-salt synthesis and composition-dependent luminescent properties of barium tungsto-molybdate-based solid solution phosphors

    Science.gov (United States)

    Xiang-Hong, He; Zhao-Lian, Ye; Ming-Yun, Guan; Ning, Lian; Jian-Hua, Sun

    2016-02-01

    Pr3+-activated barium tungsto-molybdate solid solution phosphor Ba(Mo1-zWz)O4:Pr3+ is successfully fabricated via a facile molten-salt approach. The as-synthesized microcrystal is of truncated octahedron and exhibits deep-red-emitting upon blue light excitation. Powder x-ray diffraction and Raman spectroscopy techniques are utilized to investigate the formation of solid solution phosphor. The luminescence behaviors depend on the resulting composition of the microcrystals with fixed Pr3+-doping concentration, while the host lattices remain in a scheelite structure. The forming solid solution via the substitution of [WO4] for [MoO4] can significantly enhance its luminescence, which may be due to the fact that Ba(Mo1-zWz)O4:Pr3+ owns well-defined facets and uniform morphologies. Owing to its properties of high phase purity, well-defined facets, highly uniform morphologies, exceptional chemical and thermal stabilities, and stronger emission intensity, the resulting solid solution phosphor is expected to find potential applications in phosphor-converted white light-emitting diodes (LEDs). Project supported by the Construction Fund for Science and Technology Innovation Group from Jiangsu University of Technology, China, the Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, China (Grant No. KHK1409), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, and the National Natural Science Foundation of China (Grant No. 21373103).

  9. A 1D Double Stranded Chain Complex Based on Barium Ion and 1,3,5-Triazine

    Institute of Scientific and Technical Information of China (English)

    CAO Man-Li; ZHANG Xiu-Lian; YIN Wei

    2012-01-01

    A new coordination compound [Ba(OBPT)2(H2O)2]·H2O was obtained at room temperature by the reaction of 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol(HOBPT) with BaCl2.It was characterized by elemental analysis,FTIR,TG analysis,powder X-ray diffraction analysis and single-crystal X-ray diffraction analysis.The complex crystallizes in the monoclinic P21/n space group,with a = 16.325(1),b = 6.7977(5),c = 24.164(2) ,β = 104.009(1),V = 2601.8(3) 3,Z =4,C26H22BaN10O5,Mr = 691.88,Dc = 1.766 g/cm3,F(000) = 1376 and μ(MoKα) = 1.587 mm-1.The final R = 0.0282 and wR = 0.0724 for 5095 observed reflections with I 〉 2σ(I) and R = 0.0312 and wR = 0.0744 for all data.In the complex,the barium ion is ten-coordinated with six nitrogen atoms from two ligands,two deprotonated hydroxyl oxygen atoms from another two ligands and two coordinated water molecules to form a double stranded chain.The extensive supramolecular interac-tions lead to the formation of an infinite 2D framework.

  10. Creep properties of Zr-based alloys with Zr-xNb-xSn-Fe-Cr-Mn alloying system

    International Nuclear Information System (INIS)

    To investigate the effect of Nb and Sn on the mechanical properties of Zr-based alloys with Zr-xNb-xSn-Fe-Cr-Mn alloying system, the Zr-based alloys were manufactured as two kinds of sheet specimens and tested for tensile properties and creep behaviors. PK2 alloy, which have more Sn content than Nb, showed higher tensile strength and creep resistance than PK1 alloy. With rising the applied stress and test temperature, PK1 and PK2 alloys increased the steady state creep rate and activation energy for the creep of the alloys. This behavior would be due to the effect of solid-solution hardening of Sn and the dislocation in worked structure. The stress exponent of the alloys also increased in response to rise the applied stress at the constant temperature. In the stress range of 50 to 180 MPa at 350 .deg. C and 400 .deg. C, the alloys showed creep deformation behavior due to diffusion and viscous dislocation glide mechanism below 4 of the stress exponent (n). Based on the higher stress exponent than 7. It is thought that the alloys were strained by dislocation climb mechanism at the applied stress over 100 MPa at 450 .deg. C

  11. Durable pd-based alloy and hydrogen generation membrane thereof

    Science.gov (United States)

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  12. Cyclic and Linear Polarization of Yttrium-Containing Iron-Based Amorphous Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Day, S D; Lian, T; Farmer, J C; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys are produced by rapid solidification from the melt. These alloys may possess unique mechanical and corrosion resistant properties. The chemical composition of the alloy may influence the cooling rate that is necessary for the alloys to be completely vitreous. At the same time, the corrosion resistance of the amorphous alloys may also depend on their chemical composition. This paper examines the anodic behavior of iron-based amorphous alloys containing three different concentrations (1, 3 and 5 atomic %) of yttrium (Y) in several electrolyte solutions. Results from polarization resistance potentiodynamic polarization show that when the alloy contains 5% atomic Y, the corrosion resistance decreases.

  13. Variations of color with alloying elements in Pd-free Au-Pt-based high noble dental alloys

    International Nuclear Information System (INIS)

    The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au-Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au-Pt-X (X = In, Sn, Fe, Zn) and quaternary Au-Pt-In-Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au-10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C *. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au-Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L *, and the addition of Sn gave a very light tint of red to the parent alloy. Although red-green chromaticity index a * contributed to chroma to some extent, contribution of yellow-blue chromaticity index b * was much greater in determining chroma in this Pd-free Au-Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au-Pt-based high noble dental alloys

  14. Cobalt-based ferromagnetic shape memory alloys

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Jarošová, Markéta; Drahokoupil, Jan; Majtás, Dušan; Kratochvílová, Irena; Heczko, Oleg

    Beijing : Chinese Association for Crystal Growth, 2010 - (Jiang, M.; Chen, C.). GM2 ISBN N. [International Conference on Crystal Growth /16./ (ICCG-16). 08.08.2010-13. 08.2010, Beijing] R&D Projects: GA ČR(CZ) GA101/09/0702; GA ČR GAP107/10/0824 Institutional research plan: CEZ:AV0Z10100520 Keywords : shape memory alloys * crystal growth * SBSD method * metallography Subject RIV: BM - Solid Matter Physics ; Magnetism http://210.72.154.189/Prelim_Abstract_Display.php?EID=1757

  15. Barium calcium hydroxyapatite solid solutions

    International Nuclear Information System (INIS)

    The replacement of calcium by barium in the hydroxyapatite structure by solid-state reaction at different temperatures and by precipitation from an aqueous system has been investigated by X-ray diffraction and i.r. absorption analyses. The products obtained by solid-state reaction at 1200 deg C are solid solutions over the range of barium concentration 60 to 100 atom %. The lattice dimensions and the i.r. frequencies of the solid solutions vary linearly with the atom % of barium. Only small amounts of barium can be incorporated in hydroxyapatite by precipitation from the aqueous system. (author)

  16. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.; Easton, D.S.; Heatherly, L.

    1996-06-01

    The objective of this work is to develop a new generation of structural materials based on intermetallic alloys for use at high temperatures in advanced fossil energy conversion systems. Target applications of such ultrahigh strength alloys include hot components (for example, air heat exchangers) in advanced energy conversion systems and heat engines. However, these materials may also find use as wear-resistant parts in coal handling systems (for example, nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. One potential class of such alloys is that based on Cr-Cr{sub 2}Nb alloys. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for initial development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), and excellent high-temperature strength (at 1000 to 1250{degrees}C). This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions.

  17. Strain heterogeneity and the production of coarse grains in mechanically alloyed iron-based PM2000 alloy

    OpenAIRE

    Capdevila, Carlos; Miller, U; Jelenak, H; Bhadeshia, H. K. D. H.

    2001-01-01

    Mechanically alloyed iron-based ODS alloys have the potential for application in heat exchangers for biomass processing, with gas operating temperatures and pressures of approximately 1100°C and 15–30 bar. The yttria dispersion in such alloys improves the high-temperature creep and stress rupture life. The elevated temperature strength is enhanced by the development of a coarse-grained microstructure during recrystallisation. Factors controlling the evolution of this desirable micros...

  18. Hot rolling of intermetallics FeAl phase based alloys

    Directory of Open Access Journals (Sweden)

    G. Niewielski

    2008-02-01

    Full Text Available Purpose: The one of major problem restricting universal employment of intermetallic phase base alloy istheir low plasticity which leads to hampering their development as construction materials. The following workconcentrates on possibilities to form through rolling process the alloys with various aluminium content.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axialsymmetriccompression at temperatures ranging from 900 to 1200°C at 10 s-1 strain rates. In order to analyse theprocesses which take place during deformation, the specimens after deformation were intensely cooled with water.Structural examination was carried out using light microscopy. The process was conducted on the K -350 quartorolling mill used for hot rolling of flat products. The process was conducted in some stages in at temperaturesranging from 1200-900°C:Findings: The research carried out enabled the understanding of the phenomena taking place during hot rolling ofthe investigated alloy. An alloy with 38%at. aluminium concentration can be plastically formed at a temperature of upto 900°C, which has been also confirmed in plastometric studies conducted in the form of hot compression tests.Research limitations/implications:Practical implications: The obtained sheets can be used as constructional elements working in complex stressfields, at a high temperature and corrosive environmentsOriginality/value: The tests have shown that it is possible to form the investigated alloys through rolling processingonly where shields are applied. Rolling of the alloys without shields led to the occurrence of a grid of cracks.

  19. Positron lifetime study in dilute electron irradiated lead based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moya, G. [Lab. de Physique des Materiaux, 13 Marseille (France); Li, X.H. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France); Menai, A. [Lab. de Physique des Materiaux, 13 Marseille (France); Kherraz, M. [Lab. de Physique des Materiaux, 13 Marseille (France); Amenzou, H. [Lab. de Physique des Materiaux, 13 Marseille (France); Bernardini, J. [Lab. de Metallurgie, 13 Marseille (France); Moser, P. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France)

    1995-06-01

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centred at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (orig.)

  20. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Day, S D; Lian, T; Aprigliano, L F; Hailey, P D; Farmer, J C

    2007-02-18

    Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.

  1. Positron lifetime study in dilute electron irradiated lead based alloys

    International Nuclear Information System (INIS)

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centred at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (orig.)

  2. Improved Mg-based alloys for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Sapru, K.; Ming, L.; Stetson, N.T.; Evans, J. [Energy Conversion Devices, Inc., Troy, MI (United States)

    1998-08-01

    The overall objective of this on-going work is to develop low temperature alloys capable of reversibly storing at least 3 wt.% hydrogen, allowing greater than for 2 wt.% at the system level which is required by most applications. Surface modification of Mg can be used to improve its H-sorption kinetics. The authors show here that the same Mg-transition metal-based multi-component alloy when prepared by melt-spinning results in a more homogeneous materials with a higher plateau pressure as compared to preparing the material by mechanical grinding. They have also shown that mechanically alloyed Mg{sub 50}Al{sub 45}Zn{sub 5} results in a sample having a higher plateau pressure.

  3. Positron lifetime study in dilute electron irradiated lead based alloys

    International Nuclear Information System (INIS)

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centered at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (authors). 3 figs., 9 refs

  4. Effect of B addition to hypereutectic Ti-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Louzguina-Luzgina, Larissa V. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Louzguine-Luzgin, Dmitri V. [WPI Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)], E-mail: dml@imr.tohoku.ac.jp; Inoue, Akihisa [WPI Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

    2009-04-17

    The structure and mechanical properties of Ti-Fe-B and Ti-Fe-Co-B alloys produced in the shape of the arc-melted ingots of about 25 mm diameter and 10 mm height are studied. The hypereutectic alloys showed excellent compressive mechanical properties. The structures of the high-strength and ductile hypereutectic alloys studied by X-ray diffractometry and scanning electron microscopy were found to consist of the primary cubic cP2 intermetallic compound (TiFe-phase or a solid solution on its base) and a dispersed eutectic consisting of this cP2 intermetallic compound + BCC cI2 {beta}-Ti supersaturated solid solution phase. The addition of B increased mechanical strength. Si causes embrittlement owing to the formation of alternative intermetallic compounds. The structure and deformation behaviour were studied.

  5. Structure and magnetic properties of Fe-based amorphous alloys

    Directory of Open Access Journals (Sweden)

    K. Błoch

    2013-12-01

    Full Text Available Purpose: This paper presents studies relating to the structure, magnetic properties and thermal stability of the following bulk amorphous alloys: Fe61Co10Ti3-xY6+xB20 (where x = 0 or 1 Design/methodology/approach: The investigated samples were prepared in the form of rods by using the suction-casting method. The material structures were investigated using X-ray diffractometry and Mössbauer spectroscopy. The thermal stability was determined on the basis of Differential Scanning Calorimetry (DSC plots The magnetic properties were studied using a completely automated set up for measuring susceptibility and its disaccommodation. Findings: It was found that both alloys were amorphous in the as-cast state. The DSC curve obtained for Fe61Co10Ti2Y7B20 alloy exhibited one exothermic peak, while for the Fe61Co10Ti3Y6B20 sample, two peaks were distinguishable, corresponding to the crystallization of the sample. The bifurcation of the maximum on the DSC curve for the Fe61Co10Ti3Y6B20 sample may also testify to the presence of the primary crystallizing phase (FeCo23B6 [1,2]. Data obtained from the analysis of the magnetic susceptibility disaccommodation curves clearly show that in the Fe61Co10Ti3Y6B20 alloy there is less free volumes than in the second of the investigated alloys, this results in a lesser range of relaxation time. Moreover, Fe61Co10Ti3Y6B20 alloy exhibits the better time and thermal stability of magnetic properties In both of the studied alloys, at low frequencies, the total losses were comparable with those observed in classical silicon-iron alloys. Practical implications: A Ferrometer was used for the determination of core losses. Originality/value: The paper presents some researches of the Fe-based bulk amorphous alloys obtained by the suction-casting method.

  6. Purely inorganic coatings based on nanoparticles for magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feil, Florian [DECHEMA e.V., Karl-Winnacker-Institut, Frankfurt am Main (Germany)], E-mail: feil@dechema.de; Fuerbeth, Wolfram; Schuetze, Michael [DECHEMA e.V., Karl-Winnacker-Institut, Frankfurt am Main (Germany)

    2009-03-30

    The chemical nanotechnology is offering a chance to apply stable inorganic coatings onto magnesium alloys. The cast alloy AZ91 as well as the wrought alloy AZ31 could be dip-coated with aqueous dispersions based on commercially available silica particles and various additives. The high surface activity of the nanoparticles and appropriate additives, e.g. boron, aluminium or alkali salts, help to densify these coatings under moderate conditions even suitable for those thermally precarious magnesium alloys. Another coating technique is based on the electrophoretic deposition of nanoparticles already containing all sintering aids. These particles could be synthesised by a base-catalysed sol-gel process. Polydiethoxysiloxane can act as an adhesion promoter for these coatings. Additionally concentration gradients of different oxides within these particles can adjust the coating properties, too. Usually single coatings are very thin (200-500 nm). However, multiple coating applications as well as a process involving special particle mixtures lead to coatings with a thickness of up to several micrometers. Even after thermal treatment at 200 or 400 deg. C these coatings stay crack-free. The composition and texture of these coatings were studied using IR, atomic force microscopy (AFM), scanning electron microscopy (SEM) and other techniques. Electrochemical impedance measurements show an improvement of the corrosion performance by these coatings. The coating resistance is improving with the coating thickness.

  7. Admittance Loci Based Design of a Plasmonic Structure Using Ag-Au Bimetallic Alloy Film

    OpenAIRE

    Kaushik Brahmachari; Mina Ray

    2013-01-01

    A theoretical study based on the use of admittance loci method in the design of surface plasmon resonance (SPR) based structure using Ag-Au bimetallic alloy film of different alloy fractions and nanoparticle sizes has been reported along with some interesting performance related simulated results at 633 nm wavelength. The sensitivity and other performance parameter issues of the structure based on the choice of correct alloy fraction and nanoparticle size of Ag-Au bimetallic alloy film have a...

  8. Melt Protection of Mg-Al Based Alloys

    Directory of Open Access Journals (Sweden)

    María J. Balart

    2016-05-01

    Full Text Available This paper reports the current status of Mg melt protection in view to identify near-future challenges, but also opportunities, for Mg melt protection of Mg-Al based alloys. The goal is to design and manufacture sustainable Mg alloys for resource efficiency, recycling and minimising waste. Among alternative cover gas technologies for Mg melt protection other than SF6: commercially available technologies containing―HFC-134a, fluorinated ketone and dilute SO2―and developed technologies containing solid CO2, BF3 and SO2F2, can potentially produce toxic and/or corrosive by-products. On the other hand, additions of alkaline earth metal oxides to Mg and its alloys have developed a strong comparative advantage in the field of Mg melt protection. The near-future challenges and opportunities for Mg-Al based alloys include optimising and using CO2 gas as feedstock for both melt protection and grain refinement and TiO2 additions for melt protection.

  9. Results from investigations with an instrumented impact machine on a molybdenum base alloy, nickel base alloys, and Incoloy 800

    International Nuclear Information System (INIS)

    Experiments were performed on the molybdenum base alloy TZM, the nickel base alloys Nimocast 713 LC, Inconel 625, Nimonic 86, Hastelloy S, and the iron base alloy Incoloy 800 with an instrumented impact machine. The results are discussed in terms of absorbed impact energies and dynamic fracture toughness. In all cases the agreement between the energy determined by the dial reading and the energy determined by the integration of the load vs. load point displacement diagram was excellent. A procedure for the determination of the dynamic fracture toughness for load vs. load point displacement diagrams exhibiting high oscillations using an averaged curve is proposed. Using this procedure a pronounced influence of the experiments with tup and chisel (5.0 m/s and 0.1 m/s respectively) on the dynamic fracture toughness is not detectable. Using half the drop height, i.e. halving the total energy, lowers the dynamic fracture toughness values for these types of alloys. Low absorbed impact energies are often combined with high fracture toughness values. In these cases there is no or only a small reserve in deformation and/or stable crack growth. (Auth.)

  10. Effect of Different Al/Si Ratios on the Structure and Energy Storage Properties of Strontium Barium Niobate-Based Glass-Ceramics

    Science.gov (United States)

    Xiu, Shaomei; Xiao, Shi; Xue, Shuangxi; Shen, Bo; Zhai, Jiwei

    2016-02-01

    Strontium barium niobate-based glass-ceramics (BSN-AS) with various Al/Si ratios have been prepared through melt casting followed by controlled crystallization. The effect of the various Al/Si ratios on the phase evolution, microstructure, dielectric properties, and energy storage density, and the relationship between the breakdown strength properties and the activation energy E a of BSN-AS glass-ceramics, were investigated. The results reveal that the microstructure of BSN-AS glass-ceramics gradually becomes dense and uniform, and the phenomenon of reunited grains is effectively improved in a certain range of Al/Si ratios. With the Al/Si ratios increasing, the breakdown strength increases to a maximum value and then decreases drastically. For the relationship between breakdown strength properties and activation energy E a, it was found that the various trends between breakdown properties and activation energy E a of the BSN-AS glass-ceramics are opposite. In this study, the energy storage densities reach 4.8 J/cm3 by adjusting the Al/Si ratios in the BSN-AS glass-ceramics.

  11. An easily sintered, chemically stable, barium zirconate-based proton conductor for high-performance proton-conducting solid oxide fuel cells

    KAUST Repository

    Sun, Wenping

    2014-07-25

    Yttrium and indium co-doped barium zirconate is investigated to develop a chemically stable and sintering active proton conductor for solid oxide fuel cells (SOFCs). BaZr0.8Y0.2-xInxO3- δ possesses a pure cubic perovskite structure. The sintering activity of BaZr0.8Y0.2-xInxO3- δ increases significantly with In concentration. BaZr0.8Y0.15In0.05O3- δ (BZYI5) exhibits the highest total electrical conductivity among the sintered oxides. BZYI5 also retains high chemical stability against CO2, vapor, and reduction of H2. The good sintering activity, high conductivity, and chemical stability of BZYI5 facilitate the fabrication of durable SOFCs based on a highly conductive BZYI5 electrolyte film by cost-effective ceramic processes. Fully dense BZYI5 electrolyte film is successfully prepared on the anode substrate by a facile drop-coating technique followed by co-firing at 1400 °C for 5 h in air. The BZYI5 film exhibits one of the highest conductivity among the BaZrO3-based electrolyte films with various sintering aids. BZYI5-based single cells output very encouraging and by far the highest peak power density for BaZrO3-based proton-conducting SOFCs, reaching as high as 379 mW cm-2 at 700 °C. The results demonstrate that Y and In co-doping is an effective strategy for exploring sintering active and chemically stable BaZrO3-based proton conductors for high performance proton-conducting SOFCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Investigation of the Precipitation Behavior in Aluminum Based Alloys

    KAUST Repository

    Khushaim, Muna S.

    2015-11-30

    The transportation industries are constantly striving to achieve minimum weight to cut fuel consumption and improve overall performance. Different innovative design strategies have been placed and directed toward weight saving combined with good mechanical behavior. Among different materials, aluminum-based alloys play a key role in modern engineering and are widely used in construction components because of their light weight and superior mechanical properties. Introduction of different nano-structure features can improve the service and the physical properties of such alloys. For intelligent microstructure design in the complex Al-based alloy, it is important to gain a deep physical understanding of the correlation between the microstructure and macroscopic properties, and thus atom probe tomography with its exceptional capabilities of spatially resolution and quantitative chemical analyses is presented as a sophisticated analytical tool to elucidate the underlying process of precipitation phenomena in aluminum alloys. A complete study examining the influence of common industrial heat treatment on the precipitation kinetics and phase transformations of complex aluminum alloy is performed. The qualitative evaluation results of the precipitation kinetics and phase transformation as functions of the heat treatment conditions are translated to engineer a complex aluminum alloy. The study demonstrates the ability to construct a robust microstructure with an excellent hardness behavior by applying a low-energy-consumption, cost-effective method. The proposed strategy to engineer complex aluminum alloys is based on both mechanical strategy and intelligent microstructural design. An intelligent microstructural design requires an investigation of the different strengthen phases, such as T1 (Al2CuLi), θ′(Al2Cu), β′(Al3Zr) and δ′(Al3Li). Therefore, the early stage of phase decomposition is examined in different binary Al-Li and Al-Cu alloys together with different

  13. MR Colonography with fecal tagging: Barium vs. barium ferumoxsil

    DEFF Research Database (Denmark)

    Achiam, M.P.; Chabanova, E.; Logager, V.B.; Thomsen, H.S.; Rosenberg, J.

    2008-01-01

    . Materials and Methods. Twenty patients referred to CC underwent dark lumen MRC prior to the colonoscopy. Two groups of patients received two different oral contrast agents (barium sulfate and barium sulfate/ferumoxsil) as a laxative-free fecal tagging prior to the MRC. After MRC, the contrast agent was...... rated qualitatively (with the standard method using contrast-to-wall ratio) and subjectively (using a visual analog scale [VAS]) by three different blinded observers. Results. Evaluated both qualitatively and subjectively, the tagging efficiency of barium sulfate/ferumoxsil was significantly better (P...... <.05) than barium sulfate alone. The VAS method for evaluating the tagging efficiency of contrast agents showed a high correlation (observer 11, r = 0.91) to the standard method using contrast-to-wall ratio and also a high interclass correlation (observer 11 and III = 0.89/0.85). MRC found I of 22 (5...

  14. CuZn Alloy- Based Electrocatalyst for CO2 Reduction

    KAUST Repository

    Alazmi, Amira

    2014-06-01

    ABSTRACT CuZn Alloy- Based Electrocatalyst for CO2 Reduction Amira Alazmi Carbon dioxide (CO2) is one of the major greenhouse gases and its emission is a significant threat to global economy and sustainability. Efficient CO2 conversion leads to utilization of CO2 as a carbon feedstock, but activating the most stable carbon-based molecule, CO2, is a challenging task. Electrochemical conversion of CO2 is considered to be the beneficial approach to generate carbon-containing fuels directly from CO2, especially when the electronic energy is derived from renewable energies, such as solar, wind, geo-thermal and tidal. To achieve this goal, the development of an efficient electrocatalyst for CO2 reduction is essential. In this thesis, studies on CuZn alloys with heat treatments at different temperatures have been evaluated as electrocatalysts for CO2 reduction. It was found that the catalytic activity of these electrodes was strongly dependent on the thermal oxidation temperature before their use for electrochemical measurements. The polycrystalline CuZn electrode without thermal treatment shows the Faradaic efficiency for CO formation of only 30% at applied potential ~−1.0 V vs. RHE with current density of ~−2.55 mA cm−2. In contrast, the reduction of oxide-based CuZn alloy electrode exhibits 65% Faradaic efficiency for CO at lower applied potential about −1.0 V vs. RHE with current density of −2.55 mA cm−2. Furthermore, stable activity was achieved over several hours of the reduction reaction at the modified electrodes. Based on electrokinetic studies, this improvement could be attributed to further stabilization of the CO2•− on the oxide-based Cu-Zn alloy surface.

  15. Effect of Impurities and Cerium on Stress Concentration Sensitivity of Al-Li Based Alloys

    Institute of Scientific and Technical Information of China (English)

    孟亮; 田丽

    2002-01-01

    A notch sensitivity factor was derived in order to evaluate the stress concentration sensitivity of Al-Li based alloys. The factor values for the Al-Li alloy sheets containing various contents of impurities and cerium addition were evaluated by determining the mechanical properties. It is found that the impurities Fe, Si, Na and K significantly enhance the stress concentration sensitivity of the alloys 2090 and 8090, whereas cerium addition reduces the stress concentration sensitivity to a certain degree for the high strength alloys. However, an excess amount of cerium addition in the high ductility alloy 1420 can significantly increase the stress concentration sensitivity. As compared with conventional aluminum alloys, the Al-Li based alloys generally show high stress concentration sensitivity. Therefore, a special attention must be paid to this problem in the practical application of Al-Li based alloys.

  16. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    T K Kundu; A Jana; P Barik

    2008-06-01

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the specimen lie in the range 24–40 nm. It is seen that the dielectric permittivity in doped specimens is enhanced by an order of magnitude compared to undoped barium titanate ceramics. The dielectric permittivity shows maxima at 0.3 mole% doping of Fe ion and 0.6 mole% of Ni ion. The unusual dielectric behaviour of the specimens is explained in terms of the change in crystalline structure of the specimens.

  17. New barium tantalum sulphides

    International Nuclear Information System (INIS)

    A new barium tantalum sulphide has been synthesized by the reaction of CS2 with a mixture of BaCO3 and Ta2O5. The chemical analysis of the compound was performed for 3 components (Ba, Ta and S), and the chemical composition was found to be BaTa2S5. The powder X-ray diffraction peaks were indexable on the basis of a hexagonal cell with lattices constants of a=3.32A, c=25.13A. However, the electron diffraction measurements show that the structure is more complex than that observed by powder X-ray diffraction. The compound indicates metallic behavior and Pauli paramagnetism

  18. Smart materials based on shape memory alloys: examples from Europe

    International Nuclear Information System (INIS)

    Shape memory alloys (SMAs) have become increasingly attractive as embedded actuators in polymers yielding adaptive composite structures. In particular, SMA-elements have been used to actively or passively control shape, elastic modules, internal stress level and damping capacity of such smart composites. In the passive approach, copper-base SMA-plates can be used as temperature-sensitive damping elements, an interesting solution to improve the vibrational behaviour of alpine skis for example. Active materials are obtained by the integration of pre-strained Ni-Ti-base thin wires in polymer matrix composites enabling control of the vibrational behaviour through the recovery-stress tuning technique. In this paper, some results of national research programmes in Belgium and Switzerland, mainly concerning the damping capacity, are shown and a new European project entitled ''adaptive composites with embedded shape memory alloy wires'' is presented in which partners from Belgium, Germany, Greece, Great Britain and Switzerland are collaborating. (orig.)

  19. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A. [Oak Ridge National Lab., TN (United States)] [and others

    1995-06-01

    The objective of this task is to develop a new generation of structural materials based on intermetallic alloys for use as critical hot components in advanced fossil energy conversion systems. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for this development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), excellent high-temperature strength (at 1000 to 1250{degrees}C), and potential resistance to oxidation and corrosion. This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions. The major engineering concern with Cr{sub 2}Nb and other A{sub 2}B Laves phases is their poor fracture toughness and fracture resistance at ambient temperatures. The single-phase Cr{sub 2}Nb is very hard ({approximately}800 DPH) and brittle at room temperature. Because of this brittleness, the development effort has concentrated on two-phase structures containing the hard intermetallic phase Cr{sub 2}Nb and the softer Cr-rich solid solution phase. Potential applications of Cr-Cr{sub 2}Nb alloys include hot components (for example, air heat exchangers and turbine blades) in advanced energy conversion systems and heat engines, wear-resistant parts in coal handling systems (e.g., nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. Current studies are focuses on enhancement of fracture resistance in tension at ambient temperatures and oxidation resistance above 1000{degrees}C. This report summarizes recent progress on controlling microstructure and improving the mechanical and metallurgical properties and the high-temperature corrosion behavior of Cr-Cr{sub 2}Nb alloys through alloying conditions, material processing, and heat treatment.

  20. Toughness enhancement in TiAlN-based quarternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sangiovanni, D.G., E-mail: davsan@ifm.liu.se; Chirita, V., E-mail: vio@ifm.liu.se; Hultman, L., E-mail: larhu@ifm.liu.se

    2012-03-30

    Improved toughness in hard and superhard thin films is a primary requirement for present day ceramic hard coatings, known to be prone to brittle failure during in-use conditions. We use density functional theory calculations to investigate a number of (TiAl){sub 1-x}M{sub x}N thin films in the B1 structure, with 0.06 {<=} x {<=} 0.75, obtained by alloying TiAlN with M = V, Nb, Ta, Mo and W. Results show significant ductility enhancements, hence increased toughness, in these compounds. Importantly, these thin films are also predicted to be superhard, with similar or increased hardness values, compared to Ti{sub 0.5}Al{sub 0.5} N. For (TiAl){sub 1-x}W{sub x}N the results are experimentally confirmed. The ductility increase originates in the enhanced occupancy of d-t{sub 2g} metallic states, induced by the valence electrons of substitutional elements (V, Nb, Ta, Mo, W). This effect is more pronounced with increasing valence electron concentration, and, upon shearing, leads to the formation of a layered electronic structure in the compound material, consisting of alternating layers of high and low charge density in the metallic sublattice, which in turn, allows a selective response to normal and shear stresses. - Highlights: Black-Right-Pointing-Pointer DFT calculated mechanical properties of TiAlN-based quarternary alloys. Black-Right-Pointing-Pointer (TiAl){sub 1-x}M{sub x}N alloys with M = V, Nb, Ta, Mo and W for 0.06 {<=} x {<=} 0.75. Black-Right-Pointing-Pointer Ductility enhancement induced by increased valence electron concentration (VEC). Black-Right-Pointing-Pointer Alloys predicted to be superhard, with higher hardness than TiAlN. Black-Right-Pointing-Pointer The hardness/ductility combination implies enhanced toughness in all alloys.

  1. Toughness enhancement in TiAlN-based quarternary alloys

    International Nuclear Information System (INIS)

    Improved toughness in hard and superhard thin films is a primary requirement for present day ceramic hard coatings, known to be prone to brittle failure during in-use conditions. We use density functional theory calculations to investigate a number of (TiAl)1−xMxN thin films in the B1 structure, with 0.06 ≤ x ≤ 0.75, obtained by alloying TiAlN with M = V, Nb, Ta, Mo and W. Results show significant ductility enhancements, hence increased toughness, in these compounds. Importantly, these thin films are also predicted to be superhard, with similar or increased hardness values, compared to Ti0.5Al0.5 N. For (TiAl)1−xWxN the results are experimentally confirmed. The ductility increase originates in the enhanced occupancy of d-t2g metallic states, induced by the valence electrons of substitutional elements (V, Nb, Ta, Mo, W). This effect is more pronounced with increasing valence electron concentration, and, upon shearing, leads to the formation of a layered electronic structure in the compound material, consisting of alternating layers of high and low charge density in the metallic sublattice, which in turn, allows a selective response to normal and shear stresses. - Highlights: ► DFT calculated mechanical properties of TiAlN-based quarternary alloys. ► (TiAl)1−xMxN alloys with M = V, Nb, Ta, Mo and W for 0.06 ≤ x ≤ 0.75. ► Ductility enhancement induced by increased valence electron concentration (VEC). ► Alloys predicted to be superhard, with higher hardness than TiAlN. ► The hardness/ductility combination implies enhanced toughness in all alloys.

  2. Abundance analysis of barium and mild barium stars

    CERN Document Server

    Smiljanic, R; Silva, L

    2007-01-01

    High signal to noise, high resolution spectra were obtained for a sample of normal, mild barium, and barium giants. Atmospheric parameters were determined from the FeI and FeII lines. Abundances for Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, and Gd, were determined from equivalent widths and model atmospheres in a differential analysis, with the red giant Eps Vir as the standard star. The different levels of s-process overabundances of barium and mild barium stars were earlier suggested to be related to the stellar metallicity. Contrary to this suggestion, we found in this work no evidence for barium and mild barium to have a different range in metallicity. However, comparing the ratio of abundances of heavy to light s-process elements, we found some evidence that they do not share the same neutron exposure parameter. The exact mechanism controlling this difference is still not clear. As a by-product of this analysis we identify two normal red giants misclass...

  3. Self healing of damage in Fe-based alloys

    OpenAIRE

    Zhang, S.

    2015-01-01

    Steel components can exhibit premature and low-ductility creep fracture, when exposed to high temperatures for long times. The failure arises from the formation, growth and coalescence of ultra-fine cracks and cavities. Self healing of damage is a promising new approach to enhance the lifetime of the steel components, in particular for applications at high temperatures. This thesis aims to realize the self-healing of damage in Fe-based alloys and unravel the mechanism responsible for efficien...

  4. Combined thermodynamic study of nickel-base alloys. Progress report

    International Nuclear Information System (INIS)

    Achievements during this period are the following: (1) initiation of a high-temperature study of the Ni-Ta system using the galvanic cell technique, (2) emf study of high-temperature thermodynamics in the Ni-Mo system, (3) measured heat capacity data on ordered and disordered Ni4Mo, (4) heat capacities of Ni and disordered Ni3Fe, and (5) computer correlation of thermodynamic and phase diagram data in binary Ni-base alloys

  5. High Temperature Internal Oxidation Behavior of Iron Based Alloys

    International Nuclear Information System (INIS)

    A study of growth kinetics and microstructure of internal oxides in the iron-base alloys was carried out by an optical microscope and a scanning electron microscope, so that the growth mechanisms of the oxide precipitates in the internal oxidation zone could be understood in detail. Iron-based alloys, Fe-1%Al, Fe-1%Al-1%Hf, Fe-1%Cr, Fe-1%Cr-1%Hf and Fe-2%Hf, were oxidized in a sealed quartz tube containing Fe/FeO powder mixtures which maintained the oxygen partial pressure at the FeO decomposition pressure at 800 .deg. C for the various time periods to 121 hours. Results show that the growth rate of the oxide precipitates in the internal oxidation zone is controlled by the diffusion of oxygen. The variation of the solute element and the addition of Hf in the iron-base alloys led to a change in the depth of internal oxidation zone and in the oxide morphology. The internal precipitate adopted the form of continuous needles or feathers for the Fe-Al system, whereas that in the Fe-Cr and Fe-2%Hf systems adapted the form of discontinuous crystallites, that is, spheres or polyhedral crystallites. The mechanism of this morphological evolution was explained in detail

  6. Barium aluminate cement: its application

    International Nuclear Information System (INIS)

    The technology of manufacturing barium aluminate cement from barium sulfate and alumina, using a rotary kiln for firing the clinker is described. The method of granulation of the homogenized charge was used. Conditions of using the ''to mud'' method in industry were indicated. The physical and chemical properties of barium aluminate cement are determined and the quality of several batches of cement prepared on a semi-industrial scale and their suitability for making highly refractory concretes are tested. The optimal composition of the concretes is determined as a function of the mixing water and barium aluminate cement contents. Several experimental batches of concretes were used in the linings of furnaces in the steel industry. The suitability of these cements for use in fields other than steelmaking is examined. It is established that calcium aluminate cement has certain limited applications

  7. Discovery of the Barium Isotopes

    OpenAIRE

    SHORE, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; Thoennessen, M

    2009-01-01

    Thirty-eight barium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  8. Tribological properties of laser cladding TiB2 particles reinforced Ni-base alloy composite coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Long He; Ye-Fa Tan; Xiao-Long Wang; Qi-Feng Jing; Xiang Hong

    2015-01-01

    To improve the wear resistance of aluminum alloy frictional parts,TiB2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding.The microstructure and tribological properties of the composite coatings were investigated.The results show that the composite coating contains the phases of NiAl,Ni3Al,Al3Ni2,TiB2,TiB,TiC,CrB,and Cr23C6.Its microhardness is HV0.5 855.8,which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy.The friction coefficients of the composite coatings are reduced by 6.8 %-21.6 % and 13.2 %-32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys,while the wear losses are 27.4 %-43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %-32.7 % of those of the aluminum alloys at different loads.At the light loads ranging from 3 to 6 N,the calculated maximum contact stress is smaller than the elastic limit contact stress.The wear mechanism of the composite coatings is micro-cutting wear,but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress.As the loads increase to 12 N,the calculated flash temperature rises to 332.1 ℃.The composite coating experiences multi-plastic deformation wear,micro-brittle fracture wear,and oxidative wear.

  9. Preparation and research on poisoning resistant Zr-Co based hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    LI Hualing; WANG Shumao; JIANG Lijun; ZHANG Lidong; LIU Xiaopeng; LI Zhinian

    2008-01-01

    At present,all hydrogen storage alloys are poisoned by hydrogen mixed with CO,CO2,etc,which decreases the hydrogen storage property sharply.Zr-Co based hydrogen storage alloys with good poisoning resistance were prepared by alloying,fluorinating,and electroless plating.The experiment results show that the poisoning resistance of the Zr-Co based alloy was improved remarkably after the treatments.The poisoning resistance mechanism of the Zr-Co based hydrogen storage alloys was analyzed.

  10. Corrosion of iron-base alloys by lithium

    International Nuclear Information System (INIS)

    A review of corrosion mechanisms operating in lithium-iron-base alloy systems is presented along with data obtained with thermal-convection loops of niobium-stabilized 2 1/4 percent Cr-1 percent Mo steel and types 304L and 321 stainless steels. A corrosion rate of 2.3 μm/year (0.09 mil/year) was obtained on the 2 1/4 percent Cr-1 percent Mo steel at 6000C. Considerably more mass transport of alloying constituents and a maximum corrosion rate of about 14 μm/year (0.55 mil/year) was obtained with the austenitic stainless steels. Results of metallography, x-ray fluorescence analysis, scanning electron microscopy, and weight-change data are presented and discussed

  11. Barium light source method and apparatus

    Science.gov (United States)

    Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

    2002-01-01

    Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

  12. Barium and Tc-poor S stars: Binary masqueraders among carbon stars

    OpenAIRE

    Jorissen, A; Van Eck, S.

    1997-01-01

    The current understanding of the origin of barium and S stars is reviewed, based on new orbital elements and binary frequencies. The following questions are addressed: (i) Is binarity a necessary condition to produce a barium star? (ii) What is the mass transfer mode (wind accretion or RLOF?) responsible for their formation? (iii) Do barium stars form as dwarfs or as giants? (iv) Do barium stars evolve into Tc-poor S stars? (v) What is the relative frequency of Tc-rich and Tc-poor S stars?

  13. Chemical abundances and kinematics of barium stars

    CERN Document Server

    de Castro, D B; Roig, F; Jilinski, E; Drake, N A; Chavero, C; Silva, J V Sales

    2016-01-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, $alpha$-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code {\\sc moog}. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of $alpha$-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heav...

  14. Characterization of cold-sprayed nanostructured Fe-based alloy

    International Nuclear Information System (INIS)

    The ball-milled Fe-Si alloy was used as feedstock for deposition of nanocrystalline Fe-Si by cold spraying process. The microstructure of the as-sprayed nanostructured Fe-Si was characterized by using optical microscopy, scanning electron microscopy and transmission electron microscopy. The grain sizes of the feedstock and as-sprayed deposit were estimated based on X-ray diffraction analysis. The microhardness and coercivity of the deposited Fe-Si alloy were characterized. The results showed that the as-sprayed deposit presented a dense microstructure. The mean grain size of the as-deposited Fe-Si was several tens nanometers and comparable to that of the corresponding milled feedstock. The temperature of driving gas presented little effect on the microstructure of cold-sprayed nanostructured Fe-Si deposit. The mechanical alloying induced oxygen contents up to 8 wt% in the feedstocks and subsequent deposits. The microhardness of the deposit reached about 400 Hv. The deposit achieved a high coercivity up to 190 kA/m indicating the potential possibility for applications to recording materials.

  15. Investigation of solidification dynamics of Zr-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kobold, Raphael; Herlach, Dieter [Institut fuer Materialphysik im Weltraum, Deutsches Zentrum fuer Luft- und Raumfahrt, 51170 Koeln (Germany); Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2013-07-01

    In contrast to experiments with most undercooled binary alloys the velocity of dendritic growth of a Cu50Zr50 alloy does not increase monotonically with undercooling but passes through a maximum and then decreases. To study this behaviour we investigate Zr-based alloys such as CuZr, NiZr and NiZrAl with Zirconium concentrations ranging from 36 to 64 at.% including eutectic and intermetallic phases. We use electrostatic levitation technique to melt and undercool samples with a diameter of 2-3 mm under ultra-high-vacuum conditions. Containerless processing is an effective tool for undercooling metallic melts far below their equilibrium melting temperatures since heterogeneous nucleation on container walls is completely avoided. During crystallisation of the undercooled melt the heat of crystallisation is released. The rapid increase of the temperature at the solid-liquid interface makes the solidification front visible. The velocities of the solidification front are recorded by using a high-speed camera with a maximum rate of 50.000 frames per second and are analyzed with a software for optical ray tracing. Furthermore, we try to model the growth velocity vs. the undercooling temperature and perform sample EBSD analysis with a scanning electron microscope.

  16. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  17. Pack cementation diffusion coatings for iron-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1995-02-01

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels. The Cr-Si ferrite layers have proven to be very resistant to high temperature cyclic oxidation and to pitting in aqueous solutions. The process has been patented, and is being transferred for industrial application, e.g. for water walls of utility boilers, etc. In the proposed extension of this project, the use of mixed pure metal powders in the pack will be extended to achieve similar ferrite Fe-Cr-Al coatings with excellent oxidation resistance, with the eventual transfer of the technology to industry. In other recent studies, Ni-base alloy rods were aluminized by the halide-activated pack cementation process to bring their average composition to that for the ORNL-developed Ni{sub 3}Al, for use as a welding rod. A similar effort to develop a welding rod for the ORNL Fe{sub 3}Al alloy did not yield reproducible coating compositions or growth kinetics. The continued effort to produce Duriron-type (Fe-18Si-5Cr) coatings on steels was not successful. Literature for the intrinsic diffusion coefficients suggests that this task cannot be achieved.

  18. The thermal transient effect on some nickel-based alloys

    International Nuclear Information System (INIS)

    This paper studies two nickel-based alloys after thermal transient tests. Two alloys were tested, namely Inconel 617 (UNS N06617) and Haynes 230 (UNS N06230). These materials are study for to be used in the construction of the steam generators of the future NPP reactors which must operate in severe conditions (high temperature, thermo-mechanical stress, aggressive media). The experiment consisted in thermal transient tests using a few scenarios: fast heating rates (50OC/minute) up to 1,000OC, maintaining this temperature level (0-60 minutes) and slowly/fast cooling. The metallographic analysis consisted in microstructure, micro-hardness determinations and traction tests. The average grain size was determined by linear interception method. The micro hardness was calculated by the relationship from the device technical book. On the traction diagrams the following mechanic characteristics were obtained: breaking resistance (Rm), elongation at rupture (A) and elastic modulus (E). The tested alloys were compared with the received materials. (authors)

  19. Crystallization kinetics of Fe based amorphous alloy

    Science.gov (United States)

    Shanker Rao, T.; Lilly Shanker Rao, T.

    2015-02-01

    Differential Scanning Calorimetry(DSC) experimental data under non-isothermal conditions for Fe based Metglas 2605SA1 (wt% Fe=85-95, Si=5-10, B=1-5) metallic glass ribbons are reported and discussed. The DSC Scans performed at different heating rates showed two step crystallization processes and are interpreted in terms of different models like Kissinger, Ozawa, Boswell, Augis & Bennett and Gao & Wang. From the heating rate dependence of the onset temperature (To) and the crystallization peak temperature (Tp), the kinetic triplet, activation energy of crystallization (E), Avrami exponent (n) and the frequency factor (A) are determined. The determined E for peak I is 354.5 ± 2.5 kJ/mol and for the peak II is 348.2 ± 2.2 kJ/mol, respectively. The frequency factor for peak I is 1.1 × 1023sec-1 and for peak II is 6.1 × 1020sec-1.

  20. Alloy 690 in PWR type reactors; Aleaciones base niquel en condiciones de primario de los reactores tipo PWR

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Briceno, D.; Serrano, M.

    2005-07-01

    Alloy 690, used as replacement of Alloy 600 for vessel head penetration (VHP) nozzles in PWR, coexists in the primary loop with other components of Alloy 600. Alloy 690 shows an excellent resistance to primary water stress corrosion cracking, while Alloy 600 is very susceptible to this degradation mechanisms. This article analyse comparatively the PWSCC behaviour of both Ni-based alloys and associated weld metals 52/152 and 82/182. (Author)

  1. Performance of a base isolator with shape memory alloy bars

    Institute of Scientific and Technical Information of China (English)

    Fabio Casciati; Lucia Faravelli; Karim Hamdaoui

    2007-01-01

    A new and innovative base isolation device is introduced in this paper based on extensive research carried out by the authors and their co-workers.A prototype of the device was built and experimentally tested on the shaking table.The new base isolation device consists of two disks,one vertical cylinder with an upper enlargement sustained by three horizontal cantilevers,and at least three inclined shape memory alloy(SMA) bars.The role of the SMA bars is to limit the relative motion between the base and the superstructure,to dissipate energy by their super-elastic constitutive law and to guarantee the re-centring of the device.To verify the expected performance,a prototype was built and tested under sinusoidal waves of displacement of increasing frequency with different amplitudes.It is shown that the main feature of the proposed base isolation device is that for cyclic loading,the super-elastic behavior of the alloy results in wide load-displacement loops,where a large amount of energy is dissipated.

  2. The surface spin polarization of Co-based Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fetzer, Roman; Wuestenberg, Jan-Peter; Neuschwander, Sabine; Aeschlimann, Martin; Cinchetti, Mirko [University of Kaiserslautern (Germany). Department of Physics and Research Center OPTIMAS; Jourdan, Martin; Herbort, Christian; Vilanova Vidal, Enrique; Jakob, Gerhard [University of Mainz (Germany). Institute of Physics

    2010-07-01

    Co-based Heusler alloys belong mainly to the family of half-metallic ferromagnets (HMFs). The predicted full spin polarization at the Fermi level due to the minority spin band gap makes this class of materials highly interesting for application in the field of spintronics. Thus, the characterization of the surface of Co-based Heusler compounds is extremely relevant for understanding and improving the performance of Heusler-based spintronics devices, like tunnel-magnetoresistance (TMR) junctions. Using Auger electron spectroscopy (AES) and low energy spin polarized electron photoemission, we systematically studied the correlation between chemical composition and spin polarisation of the surface. For various Co-based Heusler alloys, e.g. Co{sub 2}CrAl, Co{sub 2}MnAl and Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}, we found different degrees of spin-polarization at the very surface region. Reasons for the distinct deviation from the predicted 100% spin polarization and the dependence on the specific surface preparation procedure are discussed.

  3. Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

    International Nuclear Information System (INIS)

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, 'Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR, Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T approximate to 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature

  4. Ferromagnetic resonance in Ni-Mn based ferromagnetic Heusler alloys

    International Nuclear Information System (INIS)

    Ferromagnetic Ni-Mn based Heusler alloys undergo martensitic transformations leading to properties such as magnetic shape memory, magnetic field induced strain and magneto-caloric effects. The occurrence of such effects are closely related to the nature of magnetic interactions around the transition. These interactions can be closely examined by the ferromagnetic resonance (FMR) technique. Here, we report on the results of FMR studies performed at various temperatures in the martensite and austenite states of powder samples and discuss the mixed nature of the magnetic interactions in the martensitic state.

  5. Design of Zr-based AB2 type hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    文明芬; 王秋萍; 王兴海; 翟玉春; 陈廉

    2003-01-01

    The influences of the ratio of the radius of atom A(rA)to radius of atom B(rB),electronegativity and electron number were discussed on the Laves phase formation and the characteristics of Zr-based AB2 type hydrogen storage alloy.An enthalpy model of Zr-based AB2 alloy was obtained from known data and twelve Zr-based alloys were designed to test the model.The results show that the predicted values are in good agreement with the experimental values.The model can be used for predicting enthalpy values of Zr-based hydrogen storage alloys and settles a foundation for experiments.

  6. Dynamic pyroelectric response of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and ferroelectric ceramics of barium lead zirconate titanate

    International Nuclear Information System (INIS)

    In this work, pyroelectric properties of composite films on the basis of poly(vinylidene fluoride-trifluoroethylene) copolymer with a various level of ferroelectric ceramics inclusions of barium lead zirconate titanate solid solution were investigated by the dynamic method. The composite films were prepared by the solvent cast method. The unusual spike-like dynamic response with a quasi-stationary component was observed. It is supposed that composite films may be effectively used for pyroelectric applications. (orig.)

  7. Dynamic pyroelectric response of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and ferroelectric ceramics of barium lead zirconate titanate

    Energy Technology Data Exchange (ETDEWEB)

    Solnyshkin, A.V. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Morsakov, I.M.; Bogomolov, A.A. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); Belov, A.N.; Vorobiev, M.I.; Shevyakov, V.I.; Silibin, M.V. [National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Shvartsman, V.V. [University of Duisburg-Essen, Institute for Materials Science, Essen (Germany)

    2015-10-15

    In this work, pyroelectric properties of composite films on the basis of poly(vinylidene fluoride-trifluoroethylene) copolymer with a various level of ferroelectric ceramics inclusions of barium lead zirconate titanate solid solution were investigated by the dynamic method. The composite films were prepared by the solvent cast method. The unusual spike-like dynamic response with a quasi-stationary component was observed. It is supposed that composite films may be effectively used for pyroelectric applications. (orig.)

  8. Defect Interaction in Iron and Iron-based Alloys

    Science.gov (United States)

    Xu, Haixuan; Stocks, G. Malcolm; Stoller, Roger

    2014-03-01

    Magnetism has a profound influence on the defect properties in iron and iron-based alloys. For instance, it has been shown from first principles calculations that the helium interstitial occupies the tetrahedral site instead of octahedral site in contrast to all previous work that neglected the magnetic effects. In this study, we explore the effects of magnetism on the defect interaction, primarily interstitial-type defects, in bcc iron and Fe-Cr systems. The magnetic moment change during the interaction of two 1/2 interstitial loops in bcc iron was calculated using the ab initio locally self-consistent multiple-scattering (LSMS) method and a significant fluctuation was observed. Adding Cr significantly modifies the magnetic structure of the defects and defect interactions. In addition, the effects of magnetism on the defect energetics are evaluated. This study provides useful insights on whether magnetism can be used as a effective means to manipulate the defect evolution in iron-based structural alloys. This material is based upon work supported as part of the Center for Defect Physics, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  9. Correlation between nanostructural and electrical properties of barium titanate-based glass-ceramic nano-composites

    International Nuclear Information System (INIS)

    Highlights: → Glasses have been transformed into nanomaterials by annealing at crystallization temperature. → Glass-ceramic nano-composites are important because of their new physical. → Grain sizes are the most significant structural parameter in electronic nanocrystalline phases. → These phases are very high electrical conductivity. → Hence, glass-ceramic nanocrystals are expected to be used, as gas sensors. - Abstract: Glasses in the system BaTiO3-V2O5-Bi2O3 have been transformed into glass-ceramic nano-composites by annealing at crystallization temperature Tcr determined from DSC thermograms. After annealing they consist of small crystallites embedded in glassy matrix. The crystallization temperature Tcr increases with increasing BaTiO3 content. XRD and TEM of the glass-ceramic nano-composites show that nanocrystals were embedded in the glassy matrix with an average grain size of 25 nm. The resulting materials exhibit much higher electrical conductivity than the initial glasses. It was postulated that the major role in the conductivity enhancement of these nanomaterials is played by the developed interfacial regions between crystalline and amorphous phases, in which the concentration of V4+-V5+ pairs responsible for electron hopping, has higher than values that inside the glassy matrix. The experimental results were discussed in terms of a model proposed in this work and based on a 'core-shell' concept. From the best fits, reasonable values of various small polaron hopping (SPH) parameters were obtained. The conduction was attributed to non-adiabatic hopping of small polaron.

  10. Properties of rhenium-based master alloys prepared by powder metallurgy techniques

    Directory of Open Access Journals (Sweden)

    A. Wrona

    2010-10-01

    Full Text Available Purpose: The aim of this work was to investigate an effect of phase composition, microstructure and selected properties of the rhenium-based alloys on the conditions of their preparation by mechanical alloying followed by pressure sintering.Design/methodology/approach: The structure and mechanical and physical properties of the Re-14.0% Ni, Re-13.7% Co and Re-9.1% Fe alloys prepared from pure metal powders by mechanical alloying in a planetary mill for 10 hours followed by sintering conducted for 1 hour at the temperature of 1150°C under the pressure of 600 MPa were investigated.Findings: The mechanical alloying results in partial dissolving of alloy components into each other, whereas their structure remains unchanged, and in a decrease in average density of powders and average diameter of their particles. As a result of sintering the alloy additives almost fully pass into rhenium-based solid solution. Density and hardness of the sinter compacts and homogeneity of alloying elements distribution were higher at longer times of mechanical alloying.Research limitations/implications: The obtained results provide complementary information on the possibility of obtaining high-melting alloys by mechanical alloying and on the rate of structural transformations taking place as a result of this process.Practical implications: The obtained materials can be used as master alloys for the production of contact materials and superalloys, providing higher homogeneity of the chemical composition and microstructure of the final products.Originality/value: A new method for preparation of rhenium-based alloys by means of mechanical alloying and powder metallurgy techniques has been successfully tested.

  11. Investigation on corrosion and wear behaviors of nanoparticles reinforced Ni-based composite alloying layer

    International Nuclear Information System (INIS)

    In order to investigate the role of amorphous SiO2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO2 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-SiO2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO2 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 γ-phase and amorphous nano-SiO2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the amorphous nano-SiO2 particles slightly decreased the corrosion resistance of the Ni-Cr-Mo-Cu alloying layer. X-ray photoelectron spectroscopy (XPS) revealed that the passive films formed on the composite alloying consisted of Cr2O3, MoO3, SiO2 and metallic Ni and Mo. The dry wear test results showed that the composite alloying layer had excellent friction-reduced property, and the wear weight loss of composite alloying layer was less than 60% of that of Ni-Cr-Mo-Cu alloying layer

  12. Replacement of Co-base alloy for radiation exposure reduction in the primary system of PWR

    International Nuclear Information System (INIS)

    Of numerous Co-free alloys developed to replace Co-base stellite used in valve hardfacing material, two iron-base alloys of Armacor M and Tristelle 5183 and one nickel-base alloy of Nucalloy 488 were selected as candidate Co-free alloys, and Stellite 6 was also selected as a standard hardfacing material. These four alloys were welded on 316SS substrate using TIG welding method. The first corrosion test loop of KAERI simulating the water chemistry and operation condition of the primary system of PWR was designed and fabricated. Corrosion behaviors of the above four kinds of alloys were evaluated using this test loop under the condition of 300 deg C, 1500 psi. Microstructures of weldment of these alloys were observed to identify both matrix and secondary phase in each weldment. Hardnesses of weld deposit layer including HAZ and substrate were measured using micro-Vickers hardness tester. The status on the technology of Co-base alloy replacement in valve components was reviewed with respect to the classification of valves to be replaced, the development of Co-free alloys, the application of Co-free alloys and its experiences in foreign NPPs, and the Co reduction program in domestic NPPs and industries. 18 tabs., 20 figs., 22 refs. (Author)

  13. Palladium-based dental alloys are associated with oral disease and palladium-induced immune responses

    NARCIS (Netherlands)

    J. Muris; R.J. Scheper; C.J. Kleverlaan; T. Rustemeyer; I.M.W. van Hoogstraten; M.E. von Blomberg; A.J. Feilzer

    2014-01-01

    Background Palladium (Pd) and gold (Au) based dental alloys have been associated with oral disease. Objectives This study was designed to explore possible associations between the presence of Au-based and Pd-based dental alloys, and oral lesions, systemic complaints, and specific in vivo and in vitr

  14. Effect of ternary alloying elements on microstructure and mechanical property of Nb-Si based refractory intermetallic alloy

    International Nuclear Information System (INIS)

    Microstructure and mechanical property at room temperature and at 1773 K of Nb-Si based refractory intermetallic alloys were investigated in terms of compression and fracture toughness test. Mo and V were chosen as ternary alloying elements because of their high melting points, atomic sizes smaller than Nb. Both ternary alloying elements were found to have a significant role in modifying the microstructure from dispersed structure to eutectic-like structure in Nb solid solution/Nb5Si3 intermetallic composites. The 0.2% offset yield strength at room temperature increased with increasing content of ternary elements in Nb solid solution and volume fraction of Nb5Si3. At 1773 K, Mo addition has a positive role in increasing the yield strength. On the other hand, V addition has a role in decreasing the yield strength. The fracture toughness of ternary alloys was superior to binary alloys. Details will be discussed in correlation with ternary alloying, volume fraction of constituent phase, and the microstructure. (orig.)

  15. High Energy Storage Mg-based amorphous alloys for nickel-metal hydride battery

    International Nuclear Information System (INIS)

    Full text: Mg-based hydrogen storage alloys possess very high hydrogen absorption capacity (For example, Mg2NiH4 contains 3.6 wt.% of hydrogen). Magnesium is also abundant in nature, light in weight and low in cost. As a result, magnesium alloys have become the subject of increasing research world-wide. For a long period, it was thought that Mg-based alloy-hydrogen systems needed to be operated at high temperature (over 250 deg C) and under high hydrogen pressure. However, in recent years, some research work was successfully done to improve the hydrogen absorption kinetics of Mg2Ni by mechanical grinding and alloying. Some nano and amorphous structured Mg2Ni alloys could absorb hydrogen even at room temperature. Our research results show that it is possible to use Mg2Ni-type alloys as promising materials for increasing the negative electrode capacity of Ni-MH batteries because the theoretical discharge capacity of Mg2Ni alloy is approximately 1000 mAh/g, much higher than that of the main commercial LaNi5 alloy (which has a capacity of only about 370 mAh/g). Mg-based alloy electrodes were manufactured by a powder metallurgical technique or a induction melting method followed by ball milling with Ni and/or other metal powders. The discharge capacities of the Mg-based alloy electrodes were significantly improved by ball milling. An amorphous structure is a key factor in order to achieve high discharge capacities. The figure below shows the ball milled amorphous Mg-based alloy electrodes have very high discharge capacities by comparison with crystalline Mg2Ni alloys or commercial AB5 alloy

  16. TiAu based shape memory alloys for high temperature applications

    International Nuclear Information System (INIS)

    TiAu (equiatomic) exhibits phase transformation from B2 (ordered bcc) to thermo-elastic orthorhombic B19 martensite at about 875K and thus TiAu is categorized as high temperature shape memory alloy. In this study, recent research and developments related to TiAu based high temperature shape memory alloys will be discussed in the Introduction part. Then some results of our research group related to strengthening of TiAu based high temperature shape memory alloys will be presented. Potential of TiAu based shape memory alloys for high temperature shape memory materials applications will also be discussed. (author)

  17. TiAu based shape memory alloys for high temperature applications

    International Nuclear Information System (INIS)

    TiAu (equiatomic) exhibits phase transformaion from B2 (ordered bcc) to thermo-elastic orthorhombic B19 martensite at about 875K and thus TiAu is categorized as high temperature shape memory alloy. In this study, recent research and developments related to TiAu based high temperature shape memory alloys will be discussed in the Introduction part. Then some results of our research group related to strengthening of TiAu based high temperature shape memory alloys will be presented. Potential of TiAu based shape memory alloys for high temperature shape memory materials applications will also be discussed

  18. Electronic-Structure-Based Design of Ordered Alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Andersson, M.P.; Jacobsen, Karsten Wedel; Skriver, Hans Lomholt; Christensen, Claus H.; Nørskov, Jens Kehlet

    2006-01-01

    We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational...... discovery of a promising catalytic metal alloy surface with high reactivity and low cost....

  19. Smart materials based on shape memory alloys: examples from Europe

    Energy Technology Data Exchange (ETDEWEB)

    Gotthardt, R.; Scherrer, P. [Ecole Polytechnique Federale, Lausanne (Switzerland). Dept. de Physique; Stalmans, R. [Dept. of Metallurgy and Materials Engineering, Katholieke Univ. Leuven, Heverlee (Belgium)

    2000-07-01

    Shape memory alloys (SMAs) have become increasingly attractive as embedded actuators in polymers yielding adaptive composite structures. In particular, SMA-elements have been used to actively or passively control shape, elastic modules, internal stress level and damping capacity of such smart composites. In the passive approach, copper-base SMA-plates can be used as temperature-sensitive damping elements, an interesting solution to improve the vibrational behaviour of alpine skis for example. Active materials are obtained by the integration of pre-strained Ni-Ti-base thin wires in polymer matrix composites enabling control of the vibrational behaviour through the recovery-stress tuning technique. In this paper, some results of national research programmes in Belgium and Switzerland, mainly concerning the damping capacity, are shown and a new European project entitled ''adaptive composites with embedded shape memory alloy wires'' is presented in which partners from Belgium, Germany, Greece, Great Britain and Switzerland are collaborating. (orig.)

  20. MODELING OF NI-CR-MO BASED ALLOYS: PART II - KINETICS

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, P A; Kaufman, L; Liu, Z

    2006-07-07

    The CALPHAD approach is applied to kinetic studies of phase transformations and aging of prototypes of Ni-Cr-Mo-based alloys selected for waste disposal canisters in the Yucca Mountain Project (YMP). Based on a previous study on alloy stability for several candidate alloys, the thermodynamic driving forces together with a newly developed mobility database have been used to analyze diffusion-controlled transformations in these Ni-based alloys. Results on precipitation of the Ni{sub 2}Cr-ordered phase in Ni-Cr and Ni-Cr-Mo alloys, and of the complex P- and {delta}-phases in a surrogate of Alloy 22 are presented, and the output from the modeling are compared with experimental data on aging.

  1. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    Science.gov (United States)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  2. Tungsten and barium transport in the internal plasma of hollow cathodes

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2009-06-01

    The effect of tungsten erosion, transport, and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from 8200 h and 30 352 h ion engine wear tests. Erosion and subsequent redeposition of tungsten in the electron emission zone at the downstream end of the insert reduce the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  3. Hydrogenation properties of nanostructured Ti2Ni-based alloys and nanocomposites

    Science.gov (United States)

    Balcerzak, M.; Jakubowicz, J.; Kachlicki, T.; Jurczyk, M.

    2015-04-01

    Mechanical alloying and annealing at 1023 K for 0.5 h under an argon atmosphere were used to prepare Ti2Ni-based nanocrystalline alloys and their nanocomposites. Ti2Ni alloy was chemically modified by Pd and multi-walled carbon nanotubes. An objective of the present study is to provide data on hydrogenation properties of Ti2Ni-based alloys and compounds containing Pd and/or multi-walled carbon nanotubes. Alloys and composites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer, transmission electron microscopy, atomic force microscopy to evaluate phase composition, crystal structure, grain size, particle morphology and distribution of catalyst element. Hydrogenation/dehydrogenation properties and hydriding kinetics of materials were measured using a Sievert's apparatus. Hydrogenation properties of nanostructured Ti2Ni-based alloy and Ti2Ni-based nanocomposites were compared with those of the binary Ti2Ni compound. In present work we shown how mechanical alloying method and chemical modification by Pd and MWCNTs affected hydrogen storage properties of Ti2Ni alloy. The highest hydrogen capacity obtained for nanostructured Ti2Ni + Pd alloy equaled 2.1 wt.%. Up to our knowledge it is the highest hydrogen storage capacity obtained so far for Ti2Ni-based materials.

  4. Scattering lengths of calcium and barium isotopes

    OpenAIRE

    Dammalapati, U.; Willmann, L.; Knoop, S.

    2011-01-01

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba), in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed 40Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that ...

  5. Evaluation of different finish line designs in base metal alloys

    Directory of Open Access Journals (Sweden)

    Aghandeh R

    1999-06-01

    Full Text Available This investigation was performed according to the widespread application of base metal alloys"nand few articles published about the marginal integrity of restorations fabricated by these metals."nThree standard dies of a maxillary first premolar were prepared with a flat shoulder finish line in buccal"naspect and chamfer in palatal. One of them left with no change. On the buccal aspect of the second and"nthird dies 135?and 1607 bevel were added respectively"nUsing dual wax technique, nine wax patterns were formed on each die and casting procedure of selected"nnon precious alloy was performed by centrifugal method. Marginal gaps of each copping seated on dies"nwere measured by scanning electron microscope (SEM with X500 magnification. Measurements were"ndone on three areas of marked dies on buccal aspect. Measurement son palatal aspect was done on"nmarked midpalatal point as control."nResults and statistical analysis showed no significant difference among marginal gaps in lingual aspect."nBut on the buccal aspect there were statistically significant differences among the groups (P<0.001. Flat"nshoulder had the best marginal integrity (mean 4 micron. Shoulder with 160' bevel had the most marginal"ngap (mean 26.5 micron and shoulder with 1357 bevel was between two other groups (mean 15.7 micron.

  6. 'Age-hardened alloy' based on bulk polycrystalline oxide ceramic

    Science.gov (United States)

    Gurnani, Luv; Singh, Mahesh Kumar; Bhargava, Parag; Mukhopadhyay, Amartya

    2015-05-01

    We report here for the first time the development of 'age-hardened/toughened' ceramic alloy based on MgO in the bulk polycrystalline form. This route allows for the facile development of a 'near-ideal' microstructure characterized by the presence of nanosized and uniformly dispersed second-phase particles (MgFe2O4) within the matrix grains, as well as along the matrix grain boundaries, in a controlled manner. Furthermore, the intragranular second-phase particles are rendered coherent with the matrix (MgO). Development of such microstructural features for two-phase bulk polycrystalline ceramics is extremely challenging following the powder metallurgical route usually adopted for the development of bulk ceramic nanocomposites. Furthermore, unlike for the case of ceramic nanocomposites, the route adopted here does not necessitate the usage of nano-powder, pressure/electric field-assisted sintering techniques and inert/reducing atmosphere. The as-developed bulk polycrystalline MgO-MgFe2O4 alloys possess considerably improved hardness (by ~52%) and indentation toughness (by ~35%), as compared to phase pure MgO.

  7. A Shape Memory Alloy Based Cryogenic Thermal Conduction Switch

    Science.gov (United States)

    Notardonato, W. U.; Krishnan, V. B.; Singh, J. D.; Woodruff, T. R.; Vaidyanathan, R.

    2005-01-01

    Shape memory alloys (SMAs) can produce large strains when deformed (e.g., up to 8%). Heating results in a phase transformation and associated recovery of all the accumulated strain. This strain recovery can occur against large forces, resulting in their use as actuators. Thus an SMA element can integrate both sensory and actuation functions, by inherently sensing a change in temperature and actuating by undergoing a shape change as a result of a temperature-induced phase transformation. Two aspects of our work on cryogenic SMAs are addressed here. First - a shape memory alloy based cryogenic thermal conduction switch for operation between dewars of liquid methane and liquid oxygen in a common bulkhead arrangement is discussed. Such a switch integrates the sensor element and the actuator element and can be used to create a variable thermal sink to other cryogenic tanks for liquefaction, densification, and zero boil-off systems for advanced spaceport applications. Second - fabrication via arc-melting and subsequent materials testing of SMAs with cryogenic transformation temperatures for use in the aforementioned switch is discussed.

  8. Hydrogen determinations in a zirconium based alloy with a DSC

    International Nuclear Information System (INIS)

    In the present work a method to measure hydrogen concentrations in zirconium-based alloys was developed measuring simultaneously both, the temperature of terminal solid solubility, TTSSd, and the hydride dissolution heat, Qδ->α, using a differential scanning calorimeter (DSC). The hydrogen concentration measured with that technique, [H]Q, and the values obtained with a standard hydrogen gas meter, [H]HGM, shows a linear relation: [H]Q=(1.00+/-0.03)[H]HGM|+(9.2+/-8.0) with a correlation factor of 0.99 in the entire solubility interval in the αZr phase, from 15 to 650wt.ppm-H. The mean enthalpy value determined with two different criteria for TTSSd and Qδ->α measurements is ΔHδ->α(Q)=39.3+/-1.5kJ/mol H. The present method is specially appropriate for alloys where a partition of the overall hydrogen concentration in two phases exists. It is applicable to all hydride forming metals which ideally follows the van't Hoff law

  9. Rational design of Nb-based alloys for hydrogen separation: A first principles study

    OpenAIRE

    Byungki Ryu; Hyeon Cheol Park; Eunseog Cho; Kwanghee Kim; Jaeho Lee; Meilin Liu

    2013-01-01

    We have investigated the effect of alloying metal elements on hydrogen solubility and mechanical integrity of Nb-based alloys, Nb15M1 (where M = Ca–Zn, Ge), using first principles-based calculations. In general, the chemical interaction between the interstitial H and metal is weakened as the alloying element is changed from an early to a late transition metal, leading to lower H solubility and higher resistance to H embrittlement. This effect becomes more pronounced when a smaller alloying el...

  10. Relationship between phase composition and corrosion resistanceof Ni-Ti-Nb based shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The stability and microstructure of Ni-Ti-Nb based shape memory alloys were investigated after alloyed with elements Zr, Cr and V. In artificial seawater (3.5%NaCl) and physiological solution (5%NaCl+0.1%H2O2), the results show that the alloying elements influence the corrosion behavior of Ni-Ti-Nb alloys. Generally, Zr improves the corrosion resistance of Ni-Ti-Nb alloy, Cr reduces its corrosion resistance and V does not change the property. In order to investigate the reason of the difference,the relation of the phase components and corrosion resistance of Ni-Ti-Nb based shape memory alloys were studied by element analysis and SEM.

  11. Wear and isothermal oxidation kinetics of nitrided TiAl based alloys

    Institute of Scientific and Technical Information of China (English)

    赵斌; 吴建生; 孙坚

    2002-01-01

    Gas nitridation of TiAl based alloys in an ammonia atmosphere was c arried out. The evaluation of the surface wear resistance was performed to compare with those of the non-nitrided alloys. It is concluded that high temperature nitridation raised wear resistance of TiAl based alloys markedly. The tribol ogical behaviors of the nitrided alloys were also discussed. The oxidation kinetics of the nitrided TiAl based alloys were investigated at 800~1000 ℃ in hot air. It is concluded that nitridation is detrimental to the oxidation resistance of TiAl based alloys under the present conditions. The nitrided alloys exhibit increased oxidizing rate with the prolongation of nitridation time at 800 ℃. However, alloys nitrided at 940 ℃ for 50 hdisplay a sign of better oxidat ion resistance than the other nitrided alloys at more severe oxidizing conditions. The parabolic rate law is considered as the basis of the data processing and interpretation of the mass gainvs time data. As a comparison with it, attempts were made to fit the data with the power law. The oxidation kinetic parameter kn, kp and n were measured and the trends were discussed.

  12. Effect of bariun on the refinement of primary aluminum and eutectics in a hypoeutectic Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    LI Wei; FAN Hongyuan; ZHANG Xianju; SHEN Baoluo

    2003-01-01

    The effect of barium on the refinement of primary aluminum and on the modification of eutectics in a hypoeutectic aluminm-silicon alloy was investigated. The results indicate that barium not only modifies the eutectic silicon but also refines the primary aluminum and there is a relationship between the retained barium and the second spacing of primary aluminum. Experiments of barium-treated commercial Al-Si hypoeutectic alloy show that barium is a better modifier than sodium when there is a longer holding time.

  13. CO2 laser beam welding of AM60 magnesium-based alloy

    OpenAIRE

    BELHADJ, Asma; MASSE, Jean-Eric; Barrallier, Laurent; BOUHAFS, Mahmoud; BESSROUR, Jamel

    2010-01-01

    Magnesium alloys have a 33% lower density than aluminum alloys, whereas they exhibit the same mechanical characteristics. Their application increases in many economic sectors, in particular, in aeronautic and automotive industries. Nevertheless, their assembly with welding techniques still remains to be developed. In this paper, we present a CO2 laser welding investigation of AM60 magnesium-based alloy. Welding parameters range is determinate for the joining of 3 mm thickness sheets. The effe...

  14. Kinetics of thermal decomposition of barium zirconyl oxalate

    International Nuclear Information System (INIS)

    Kinetics of the thermal decomposition of anhydrous barium zirconyl oxalate and a carbonate intermediate have been studied. Decomposition of the anhydrous oxalate, though it could be explained based on a contracting-cube model, is quite complex. Kinetics of decomposition of the intermediate carbonate Ba2Zr2O5CO3 is greatly influenced by thermal effects during its formation. (α-t) curves are sigmoidal and obey a power law equation followed by first order decay. Presence of carbon in the vacuum-prepared carbonate has a strong deactivating effect. Decomposition of the carbonate is accompanied by growth in particle size of the product barium zirconate. (Author)

  15. Maintenance of Ni-based alloy at PWR plant

    International Nuclear Information System (INIS)

    Kansai Electric owns 11 PWR plants. At our PWR plants, we are taking various preventive maintenance measures on Ni-based alloy according to the prediction of possible trouble while past trouble occurred at overseas plants due to Primary Water Stress Corrosion Cracking (PWSCC) being considered. In addition, we are making an effort to put new maintenance techniques into practical use by conducting demonstration tests to confirm their applicability to actual plants. We have replaced reactor vessel heads at 7 plants with new ones. At the other 4 plants, we took, measures to reduce the temperature of reactor vessel head top to delay the timing of PWSCC occurrence. We are carrying out the constant load tests to predict the timing of PWSCC occurrence at these 4 plants. It is planned to conduct non-destructive inspections at an appropriate timing based on the result of the prediction. Based on the prediction of the timing of PWSCC occurrence at bottom-mounted instrumentation (BMI), we have developed water jet peening (WJP) technique to reduce residual stress and applied the technique to our plants successively. Meanwhile, a technique to cut and eliminate cracking has been developed. In addition, capping technique, which covers overall the concerned nozzle on the outer surface of the reactor vessel, has been also established. For alloy 132/82 weld metal for the connection, we are conducting ultrasonic inspection at our plants successively. In order to prepare against PWSCC occurrence, we have also established a technique to replace the entire section of concerned short piping with new one. (author)

  16. Mechanisms of improving the cyclic stability of V-Ti-based hydrogen storage electrode alloys

    International Nuclear Information System (INIS)

    Research highlights: → The corrosion resistance of V-based phase is much lower than that of C14 Laves phase of V-Ti-based alloys. → The addition of Cr which mostly distributes in V-based phase can effectively increase the anti-corrosion ability of V-Ti-based alloys. → The addition of Cr which mostly distributes in V-based phase can effectively increase the anti-corrosion ability of V-Ti-based alloys. - Abstract: In this work, the mechanisms of improving the cyclic stability of V-Ti-based hydrogen storage electrode alloys were investigated systemically. Several key factors for example corrosion resistance, pulverization resistance and oxidation resistance were evaluated individually. The V-based solid solution phase has much lower anti-corrosion ability than C14 Laves phase in KOH solution, and the addition of Cr in V-Ti-based alloys can suppress the dissolution of the main hydrogen absorption elements of the V-based phase in the alkaline solution. During the charge/discharge cycling, the alloy particles crack or break into several pieces, which accelerates their corrosion/oxidation and increases the contact resistance of the alloy electrodes. Proper decreasing the Vickers hardness and enhancing the fracture toughness can increase the pulverization resistance of the alloy particles. The oxidation layer thickness on the alloy particle surface obviously increases during charge/discharge cycling. This deteriorates their electro-catalyst activation to the electrochemical reaction, and leads to a quick degradation. Therefore, enhancing the oxide resistance can obviously improve the cyclic stability of V-Ti-based hydrogen storage electrode alloys.

  17. Mechanical and microstructural characterization of the nickel base alloy (Alloy 600) after heat treatment

    International Nuclear Information System (INIS)

    The characterization of microstructural and mechanical properties of cold rolled and heat treated alloys 600 made in Brazil were investigated. The recovery and recrystallization behavior as well as solubilization and aging have been studied using optical, scanning electron and transmission electron microscopy. Microhardness and tensile testing have been carried out. The recovery process of the cold rolled alloy 600 occurred until 600 deg C and the recrystallization stage was situated between 600 and 850 deg C. The primary recrystallization temperature was obtained at 850 deg C after 1 hour (isochronal heat treatments). The aged alloy 600 shows carbide precipitation on grains bu with ductility maintenance. (author)

  18. On the role of alloying elements in the formation of serrated grain boundaries in Ni-based alloys

    International Nuclear Information System (INIS)

    Ni-based model alloys were used to study the effect of alloying elements, namely Cr, Mo, C and Zr on the occurrence of grain boundary serration. The model alloys were free of aluminum to exclude precipitation of second-phase γ'. Similarly, the carbon content was very low, when present, to prevent precipitation of carbides. A special heat treatment involving slow cooling was used to promote grain boundary serration. No significant sign of serration was observed for Ni-10Cr-10Mo, Ni-20Cr-10Mo and Ni-10Cr-10Mo-0.05C model alloys. However, substantial serration was observed for Ni-10Cr-10Mo-0.5Zr and Ni-20Cr-0.5Zr model alloys. Serrated grain boundaries were observed in the absence of either γ' or carbides. Zirconium-rich precipitates were recognized at serrated grain boundaries though their involvement in the occurrence of serration was doubtful. A mechanism of grain boundary serration formation is proposed.

  19. On the role of alloying elements in the formation of serrated grain boundaries in Ni-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Terner, Mathieu; Hong, Hyun-Uk; Lee, Je-Hyun [Changwon National Univ. (Korea, Republic of). Dept. of Materials Science and Engineering; Choi, Baig-Gyu [Korea Institute of Materials Science, Changwon (Korea, Republic of). High Temperature Materials Group

    2016-03-15

    Ni-based model alloys were used to study the effect of alloying elements, namely Cr, Mo, C and Zr on the occurrence of grain boundary serration. The model alloys were free of aluminum to exclude precipitation of second-phase γ'. Similarly, the carbon content was very low, when present, to prevent precipitation of carbides. A special heat treatment involving slow cooling was used to promote grain boundary serration. No significant sign of serration was observed for Ni-10Cr-10Mo, Ni-20Cr-10Mo and Ni-10Cr-10Mo-0.05C model alloys. However, substantial serration was observed for Ni-10Cr-10Mo-0.5Zr and Ni-20Cr-0.5Zr model alloys. Serrated grain boundaries were observed in the absence of either γ' or carbides. Zirconium-rich precipitates were recognized at serrated grain boundaries though their involvement in the occurrence of serration was doubtful. A mechanism of grain boundary serration formation is proposed.

  20. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    International Nuclear Information System (INIS)

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x1020 n/cm2 at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed

  1. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, R.; Mills, W.J.; Kammenzind, B.F.; Burke, M.G.

    1999-07-01

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.

  2. Phases stability of shape memory alloys Cu based under irradiation

    International Nuclear Information System (INIS)

    The effects of irradiation on the relative phase stability of phases related by a martensitic transformation in copper based shape memory alloys were studied in this work.Different kind of particles and energies were employed in the irradiation experiments.The first kind of irradiation was performed with 2,6 MeV electrons, the second one with 170 keV and 300 keV Cu ions and the third one with swift heavy ions (Kr, Xe, Au) with energies between 200 and 600 MeV.Stabilization of the 18 R martensite in Cu-Zn-Al-Ni induced by electron irradiation was studied.The results were compared to those of the stabilization induced by quenching and ageing in the same alloy, and the ones obtained by irradiation in 18 R-Cu-Zn-Al alloys.The effects of Cu irradiation over b phase were analyzed with several electron microscopy techniques including: scanning electron microscopy (S E M), high resolution electron microscopy (H R E M), micro diffraction and X-ray energy dispersive spectroscopy (E D S). Structural changes in Cu-Zn-Al b phase into a closed packed structure were induced by Cu ion implantation.The closed packed structures depend on the irradiation fluence.Based on these results, the interface between these structures (closed packed and b) and the stability of disordered phases were analyzed. It was also compared the evolution of long range order in the Cu-Zn-Al and in the Cu-Zn-Al-Ni b phase as a function of fluence.The evolution of the g phase was also compared. Both results were discussed in terms of the mobility of irradiation induced point defects.Finally, the effects induced by swift heavy ions in b phase and 18 R martensite were studied. The results of the irradiation in b phase were qualitatively similar to those produced by irradiation with lower energies. On the contrary, nano metric defects were found in the irradiated 18 R martensite.These defects were characterized by H R E M.The characteristic contrast of the defects was associated to a local change in the

  3. Elevated temperature fretting fatigue of nickel based alloys

    Science.gov (United States)

    Gean, Matthew C.

    This document details the high temperature fretting fatigue of high temperature nickel based alloys common to turbine disk and blade applications. The research consists of three area of focus: Experiments are conducted to determine quantitatively the fretting fatigue lives of advanced nickel based alloys; Analytical tools are developed and used to investigate the fretting fatigue response of the material; Fractographic analysis of the experimental results is used to improve the analytical models employed in the analysis of the experiments. Sixty three fretting fatigue experiments were conducted at 649 °C using a polycrystalline Nickel specimen in contact with directionally solidified and single crystal Nickel pads. Various influences on the fretting fatigue life are investigated. Shot peened Rene' 95 had better fretting fatigue life compared to shot peened Rene' 88. Shot peening produced a 2x increase in life for Rene' 95, but only a marginal improvement in the fretting fatigue life for Rene' 88. Minor cycles in variable amplitude loading produces significant damage to the specimen. Addition of occasional overpeaks in load produces improvements in fretting fatigue life. Contact tractions and stresses are obtained through a variety of available tools. The contact tractions can be efficiently obtained for limited geometries, while FEM can provide the contact tractions for a broader class of problems, but with the cost of increased CPU requirements. Similarly, the subsurface contact stresses can be obtained using the contact tractions as a boundary condition with either a semi-analytical FFT method or FEM. It is found that to calculate contact stresses the FFT was only marginally faster than FEM. The experimental results are combined with the analysis to produce tools that are used to design against fretting fatigue. Fractographic analysis of the fracture surface indicates the nature of the fretting fatigue crack behavior. Interrupted tests were performed to analyze

  4. Laser welding of AZ61 magnesium-based alloys

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun; Zhang Yihui

    2006-01-01

    Laser welding of AZ61 magnesium alloys was carried out asing a CO2 laser weldingexperimental system.The welding properties of AZ61 sheets with different thickness were investigated.The effect of processing parameters including laser power, welding speed and protection gas flow was researched.The results show that laser power and welding speed have large effect on the weld width and joint dimensions.Protection gas flow has relatively slight effect on the weld width.The property test of three typical joints indicates that microhardness and tensile strength in weld zone are higher than that of AZ61 base metal.Joints with good appearance and excellent mechanical properties can be produced using CO2 laser welding method.The microstructure with small grains in weld zone is believed to be responsible for the excellent mechanical properties of AZ61 joints.

  5. Study of superficial films and of electrochemical behaviour of some nickel base alloys and titanium base alloys in solution representation of granitic, argillaceous and salted ground waters

    International Nuclear Information System (INIS)

    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 200C and 900C 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 900C, Ti and Ti-Pd show very high passivation aptitude and a broad passive potential range. Alloying Pd increases cathodic overpotential and also transpassive potential. It makes the alloy less sensitive to the temperature effect. Optical Glow Discharge Spectra show three parts in the composition depth profiles of surface films on alloys. XPS and SIMS spectrometry analyses are also carried out. Electron microscopy observation shows that passive films formed on Ti and Ti-Pd alloy have amorphous structure. Analysis of the alloy constituents dissolved in solutions, by radioactivation in neutrons, gives the order of magnitude of the Ni base alloy corrosion rates in various media. It also points out the preferential dissolution of alloying iron and in certain cases of chromium

  6. Evaluation of Nb-base alloys for the divertor structure in fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Purdy, I.M. [Argonne National Laboratory, Upton, IL (United States)

    1996-04-01

    Niobium-base alloys are candidate materials for the divertor structure in fusion reactors. For this application, an alloy should resist aqueous corrosion, hydrogen embrittlement, and radiation damage and should have high thermal conductivity and low thermal expansion. Results of corrosion and embrittlement screening tests of several binary and ternary Nb alloys in high-temperature water indicated the Mb-1Zr, Nb-5MO-1Zr, and Nb-5V-1Z4 (wt %) showed sufficient promise for further investigation. These alloys, together with pure Nb and Zircaloy-4 have been exposed to high purity water containing a low concentration of dissolved oxygen (<12 ppb) at 170, 230, and 300{degrees}C for up to {approx}3200 h. Weight-change data, microstructural observations, and qualitative mechanical-property evaluation reveal that Nb-5V-1Zr is the most promising alloy at higher temperatures. Below {approx}200{degrees}C, the alloys exhibit similiar corrosion behavior.

  7. Shape Memory Alloy-Based Periodic Cellular Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort will develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular structures...

  8. Hydrogen embrittlement considerations in niobium-base alloys for application in the ITER divertor

    International Nuclear Information System (INIS)

    The ITER divertor will be subjected to hydrogen from aqueous corrosion by the coolant and by transfer from the plasma. Global hydrogen concentrations are one factor in assessing hydrogen embrittlement but local concentrations affected by source fluxes and thermotransport in thermal gradients are more important considerations. Global hydrogen concentrations in some corrosion-tested alloys will be presented and interpreted. The degradation of mechanical properties of Nb-base alloys due to hydrogen is a complex function of temperature, hydrogen concentration, stresses and alloy composition. The known tendencies for embrittlement and hydride formation in Nb alloys are reviewed. (orig.)

  9. Development and Making of New Jewellery Palladium Based Alloys at JSC "Krastsvetmet"

    Institute of Scientific and Technical Information of China (English)

    YEFIMOV V. N.; MAMONOV S. N.; SHULGIN D. R.; YELTSIN S. I.

    2012-01-01

    Complex of research and development work aimed at implementation of jewellery palladium based alloys technology has been carried out at JSC Krastsvetmet.A range of palladium alloys jewellery fabrication has been organized.Compositions of a number of jewellery palladium alloys grade 850,900,950 and 990 have been proposed,their production and application in jewellery manufacture has been organized.To produce palladium alloys induction melting in inert atmosphere and melt pouring into a copper mould has been used.The ingots heat treatment conditions,as well as semi-finished jewelry plastic deformation parameters have been determined.

  10. Scanning electron and tunneling microscopy of palladium-barium emitters

    International Nuclear Information System (INIS)

    The results of study of metal-alloyed palladium-barium emitters' of modern very high frequency high-powered electronic vacuum tubes by scanning electron microscopy (SEM) and scanning tunneling microscopy/spectroscopy (STM/STS) are presented. Since the Pd/Ba foil surface is fairly smooth and is not oxidized in air STM/STS investigations are carried out in air in normal laboratory environment. SEM and STM images show that the emitter surface has a complex porous structure. The cathode surface study by STS in tunneling gap modulation mode allowed to take a map of phase distribution with various work function values and high lateral resolution. Obtained images demonstrate the presence of three phases on the Pd/Ba emitter surface, viz. barium-oxygen compounds, intermetallic, and palladium. As it is seen from presented STS image the phase with a low work function value (barium oxides) is concentrated along boundaries of the substance inclusions with work function corresponding to the intemetallic compound Pd5Ba. This supports the model of low work function areas obtained via Ba segregation from the intermetallic compound and oxidation. The presented methods may be used in the Pd/Ba cathode manufacturing process for increasing the yield of electronic devices in microwave tube production and optimize the emitters' characteristics

  11. Cu-based shape memory alloys with enhanced thermal stability and mechanical properties

    International Nuclear Information System (INIS)

    Cu-based shape memory alloys were developed in the 1960s. They show excellent thermoelastic martensitic transformation. However the problems in mechanical properties and thermal instability have inhibited them from becoming promising engineering alloys. A new Cu-Zn-Al-Mn-Zr Cu-based shape memory alloy has been developed. With the addition of Mn and Zr, the martensitic transformation behaviour and the grain size ca be better controlled. The new alloys demonstrates good mechanical properties with ultimate tensile strenght and ductility, being 460 MPa and 9%, respectively. Experimental results revealed that the alloy has better thermal stability, i.e. martensite stabilisation is less serious. In ordinary Cu-Zn-Al alloys, martensite stabilisation usually occurs at room temperature. The new alloy shows better thermal stability even at elevated temperature (∝150 C, >Af=80 C). A limited small amount of martensite stabilisation was observed upon ageing of the direct quenched samples as well as the step quenched samples. This implies that the thermal stability of the new alloy is less dependent on the quenching procedure. Furthermore, such minor martensite stabilisation can be removed by subsequent suitable parent phase ageing. The new alloy is ideal for engineering applications because of its better thermal stability and better mechanical properties. (orig.)

  12. An experimental study of the magnetic ordering in Pd-based Fe and Mn alloys

    International Nuclear Information System (INIS)

    This thesis presents the results of an investigation on the magnetic ordering phenomena in some Pd based alloys with small concentrations of magnetic impurities. It has been the object to explore the ordering mechanisms in these alloys which lead to various types of magnetism at low temperature. The experimental techniques used are described. (Auth.)

  13. Tungsten and Barium Transport in the Internal Plasma of Hollow Cathodes

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2008-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushedback to the emitter surface by the electric field and drag from the xenon ion flow. Thisbarium ion flux is sufficient to maintain a barium surface coverage at the downstream endgreater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length,so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollowcathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  14. Properties and Application of Iron-based Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Li Jian-chen; Jiang Qing; Dai Jun

    2005-01-01

    The properties of FeMnSiCrNi shape memory alloy were investigated. The results show that the best shape memory effect of Fel4Mn6Si9Cr5Ni alloy is 85%. The transformation amount of the ε→γ transformation is not complete after heating the alloy to 1000 K, As and Af points drop with increased transformation enthalpy ( △Hγ→ε) by thermal cycling and increased prestrain. The alloy shows also good creep and stress relaxation resistance. In addition, the alloy having a tensile force of 20 kN and a sealing pressure of 6 MPa can satisfy requirements for possible industrial application on pipe joints.

  15. Mechanical Properties of Ni-base ODS Alloy Influenced by Process Variables

    International Nuclear Information System (INIS)

    According to a recent investigation, no proven industrial technology could be directly used for such applications. For example, extensive work on Alloy 617 which is the candidate material for the intermediate heat exchanger (IHX) in very high temperature reactors (VHTR) shows that Alloy 617 exhibit quite good creep properties, the maximum service temperature of Alloy 617 is much less than that required for the VHTR-IHX applications. In this regard, oxide dispersion strengthened (ODS) materials have received a great attention owing to their excellent mechanical properties at higher temperatures, e.g., creep resistance. As part of an alloy development program for nickel base ODS alloy, we have produced an ODS Alloy 617 via mechanical alloying and hot extrusion, and characterized its microstructural evolution during the process and evaluated mechanical properties at elevated temperatures. The current work reports the effects of process variables and yttria contents on the microstructure and mechanical properties of ODS Alloy 617. From the experimental work on the influences of yttria content, and process variables such as hot-extrusion ratio and hydrogen reduction on the mechanical properties of ODS Alloy 617, it is concluded that reduction of yttria contents from 0.6 wt.% to 0.45 wt.% and increasing hot extrusion ratio from 6.25:1 to 9:1 improve the ductility at elevated temperatures without the sacrifice of strength

  16. NANOSCALE BARIUM HYDROSILICATES: CHOOSING THE SYNTHESIS TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    GRISHINA Anna Nikolaevna

    2013-08-01

    Full Text Available Cement concretes are the most used materials in modern civil engineering. Due to that such materials draw great attention both in the Russian Federation and abroad. The possibility to enhance the manufacturability and operational properties of concretes results in significant reduction of overall operating costs. Many enhancement methods have been elaborated. Among them there is one based on introduction of calcium hydrosilicates into construction composition. The authors set up a hypothesis that similarity between properties and structures of different hydrosilicates (for example, alkaline earth metals and metals of the second group will provide similar increased operational characteristics. The specialists of Research and Educational Center «Nanotechnology» are developing cement composites nanomodification methods which include introduction of nanodimensional barium hydrosilicates particles. The synthesis of barium hydrosilicates particles can be done with the use of many technologies, different by energy consumption or performing complexity. Taking into account both these factors, one can assume that low-temperature sol-gel synthesis from diluted water solutions is the proper technology. The present paper shows that this assumption is correct. The selection of certain technology is made by the means of multiobjective optimization, which is in turn is performed by the means of linear scalarization. This method, while not always giving the Pareto optimal solutions, can be easily implemented. The particle size distribution is taken into consideration during selection of objectives and weights. It is shown that selected technology allows manufacturing nanoparticles with median size about 30 nm.

  17. Effects of Cr and Nb contents on the susceptibility of Alloy 600 type Ni-base alloys to stress-corrosion cracking in a simulated BWR environment

    International Nuclear Information System (INIS)

    In order to discuss the effects of chromium and niobium contents on the susceptibility of Alloy 600 type nickel-base alloys to stress-corrosion cracking in the BWR primary coolant environment, a series of creviced bent-beam (CBB) tests were conducted in a high-temperature, high-purity water environment. Chromium, niobium, and titanium as alloying elements improved the resistivity to stress-corrosion cracking, whereas carbon enhanced the susceptibility to it. Alloy-chemistry-based correlations have been defined to predict the relative resistances of alloys to stress-corrosion cracking. A strong correlation was found, for several heats of alloys, between grain-boundary chromium depletion and the susceptibility to stress-corrosion cracking

  18. Strengthening mechanisms of indirect-extruded Mg–Sn based alloys at room temperature

    Directory of Open Access Journals (Sweden)

    Wei Li Cheng

    2014-12-01

    Full Text Available The strength of a material is dependent on how dislocations in its crystal lattice can be easily propagated. These dislocations create stress fields within the material depending on their intrinsic character. Generally, the following strengthening mechanisms are relevant in wrought magnesium materials tested at room temperature: fine-grain strengthening, precipitate strengthening and solid solution strengthening as well as texture strengthening. The indirect-extruded Mg–8Sn (T8 and Mg–8Sn–1Al–1Zn (TAZ811 alloys present superior tensile properties compared to the commercial AZ31 alloy extruded in the same condition. The contributions to the strengthen of Mg–Sn based alloys made by four strengthening mechanisms were calculated quantitatively based on the microstructure characteristics, physical characteristics, thermomechanical analysis and interactions of alloying elements using AZ31 alloy as benchmark.

  19. Microstructure and tensile properties of magnesium alloy modified by Si/Ca based refiner

    Institute of Scientific and Technical Information of China (English)

    DUAN Zhi-chao; SUN Yang-shan; WEI Yu; DU Wen-wen; XUE Feng; ZHU Tian-bai

    2005-01-01

    Microstructure and mechanical properties of pure magnesium and AZ31 alloy with Ca/Si based refiner addition were investigated. The results indicate that addition of Ca/Si based refiners to pure magnesium and AZ31 alloy results in remarkable microstructure refinement. With proper amount of refiner addition, the grain size in as cast ingots can be one order of magnitude lower than that without refiner addition. Small amount of refiner addition to AZ31 alloy increases both ultimate strength and yield strength significantly, while the ductility of the alloy with refiner addition is similar to that without refiner addition. Addition of refiner improves the deformability of AZ31 alloy and extruded or hot rolled specimens (rods or sheets) with refiner addition exhibit higher surface quality and mechanical properties than those without refiner addition.

  20. Scale formation on Ni-based alloys in simulated solid oxide fuel cell interconnect environments

    Energy Technology Data Exchange (ETDEWEB)

    Ziomek-Moroz, Margaret; Cramer, Stephen D.; Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Singh, P. (PNNL); Windisch, C.F. (PNNL); Johnson, C.D. (NETL); Schaeffer, C. (National Energy Research Laboratory, Morgantown, WV)

    2004-11-01

    Recent publications suggest that the environment on the fuel side of the bi-polar stainless steel SOFC interconnects changes the oxidation behavior and morphology of the scale formed on the air side. The U.S. Department of Energy Albany Research Center (ARC), has examined the role of such exposure conditions on advanced nickel base alloys. Alloy formulations developed at ARC and commercial alloys were studied using X-ray diffraction (XRD) and Raman spectroscopy. The electrical property of oxide scales formed on selected alloys was determined in terms of areaspecific resistance (ASR). The corrosion behavior of ARC nickel-based alloys exposed to a dual environment of air/ H2 were compared to those of Crofer 22APU and Haynes 230.

  1. The problem of the barium stars

    Science.gov (United States)

    Bohm-Vitense, E.; Nemec, J.; Proffitt, C.

    1984-01-01

    Ultraviolet observations of barium stars and other cool stars with peculiar element abundances are reported. Those observations attempted to find hot white dwarf companions. Among six real barium stars studied, only Zeta Cap was found to have a white dwarf companion. Among seven mild, or marginal, barium stars studied, at least three were found to have hot subluminous companions. It is likely that all of them have white dwarf companions.

  2. Radioisotope barium sulphate gauge MZB-2

    International Nuclear Information System (INIS)

    A method and the gauge for measuring content of barium sulphate are described. The gauge is intended for fast determination of barium sulphate in barite ore and in output products of the enrichment process. The measuring range 60-100% of BaSO4, accuracy ±1% and measuring time 60 s were reached. The barium sulphate gauge is used in barite mine ''Boguszow'' in Poland. (author)

  3. Perpendicular Magnetic Anisotropy in Co-Based Full Heusler Alloy Thin Films

    Science.gov (United States)

    Wu, Y.; Xu, X. G.; Miao, J.; Jiang, Y.

    2015-12-01

    Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.

  4. Detection of residual Al-base core in Ni alloy with Gd-tagging neutron radiography

    International Nuclear Information System (INIS)

    Detection of residual aluminum-base core in nickel alloy is important for manufacturing blades of an aero-engine. Because of the strong penetrability, neutrons are more effective than X-rays to detect residual material in the nickel alloy blade. In this paper, both theoretical calculation and experiments on an accelerator-based neutron source at Peking University are used to verify the feasibility of Gd-tagging neutron radiography in detecting residual aluminum-base core in the nickel alloy. The results show that the technique can achieve a sensitivity of 0.2 mg for the residual core detection. (authors)

  5. Short-range order and fractal cluster structure of aggregates of barium titanate microparticles in a composite based on cyano-ethyl ester of polyvinyl alcohol

    Science.gov (United States)

    Krasovskii, A. N.; Novikov, D. V.; Vasina, E. S.; Matveichikova, P. V.; Sychev, M. M.; Rozhkova, N. N.

    2015-12-01

    The distribution of barium titanate (BaTiO3) microparticles in the matrix of cyano-ethyl ester of polyvinyl alcohol and the change in the surface energy upon introduction of shungite carbon nanoclusters into the dielectric composite have been investigated using the methods of scanning electron microscopy and contact angles. The computer processing of the electron microscopy data has demonstrated that the introduction of 0.04% shungite carbon nanoparticles into the composite leads to a decrease in the spatial homogeneity of the quasi-lattice and to an increase in the local density distribution of BaTiO3 microparticles, as well as in the correlation length corresponding to the formation of an infinite cluster of BaTiO3 particles. It has been found that, in this case, the surface energy and dielectric permittivity of the composite extremely increase.

  6. ONE CASE REPORT OF ACUTE POISONING BY BARIUM CARBONATE

    Institute of Scientific and Technical Information of China (English)

    GE Qin-min; BIAN Fan; WANG Shu-yun; SHEN Sheng-hui

    2009-01-01

    @@ Most barium poisoning cases were caused by oral intake by mistake. Recent years, barium carbonate poisoning has been rare to be reported. Here we reported a case of acute barium carbonate toxication taken orally on purpose.

  7. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    Science.gov (United States)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  8. Imprecise knowledge based design and development of titanium alloys for prosthetic applications.

    Science.gov (United States)

    Datta, S; Mahfouf, M; Zhang, Q; Chattopadhyay, P P; Sultana, N

    2016-01-01

    Imprecise knowledge on the composition-processing-microstructure-property correlation of titanium alloys combined with experimental data are used for developing rule based models for predicting the strength and elastic modulus of titanium alloys. The developed models are used for designing alloys suitable for orthopedic and dental applications. Reduced Space Searching Algorithm is employed for the multi-objective optimization to find composition, processing and microstructure of titanium alloys suitable for orthopedic applications. The conflicting requirements attributes of the alloys for this particular purpose are high strength with low elastic modulus, along with adequate biocompatibility and low costs. The 'Pareto' solutions developed through multi-objective optimization show that the preferred compositions for the fulfilling the above objectives lead to β or near β-alloys. The concept of decision making employed on the solutions leads to some compositions, which should provide better combination of the required attributes. The experimental development of some of the alloys has been carried out as guided by the model-based design methodology presented in this research. Primary characterizations of the alloys show encouraging results in terms of the mechanical properties. PMID:26398780

  9. Electronic-Structure-Based Design of Ordered Alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Andersson, M.P.; Jacobsen, Karsten Wedel; Skriver, Hans Lomholt; Christensen, Claus H.; Nørskov, Jens Kehlet

    2006-01-01

    We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational...... discovery of a promising catalytic metal alloy surface with high reactivity and low cost....... design of other materials as well. A central problem is how to treat the huge number of compounds that can be envisioned by varying the concentrations and the number of the elements involved. We discuss various strategies for approaching this problem and show how one strategy has led to the computational...

  10. Formation and Corrosion Resistance of Amorphous Ti Base Alloys

    OpenAIRE

    Naka, M.; Okada, T.; T. Matsui

    1996-01-01

    Corrosion resistant amorphous Ti-B and Ti-Si alloys were prepared on various substrates by RF sputtering. The alloying of B content of 8 at% or more stabilizes the amorphous structure. The corrosion properties of Ti alloys were evaluated by measuring the polarization curves in 1N HCl. Although the addition of B to crystalline bulky Ti shifts the corrosion potentials of Ti to the less nobles of -0.5 V(SCE) or less, that of B to amorphous sputtered Ti moves the corrosion potentials to the noble...

  11. Electron-ion plasma modification of Al-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yurii, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 634050, Russia, Tomsk, 36 Lenina Str (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050, Russia, Tomsk, 30 Lenina Str (Russian Federation); Rygina, Mariya, E-mail: l-7755me@mail.ru [National Research Tomsk Polytechnic University, Tomsk, 634050, Russia, Tomsk, 30 Lenina Str (Russian Federation); Petrikova, Elizaveta, E-mail: elizmarkova@yahoo.com; Krysina, Olga, E-mail: krysina-82@mail.ru; Teresov, Anton, E-mail: tad514@sibmail.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 634050, Russia, Tomsk, 36 Lenina Str (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irina-ikonnikova@yandex.ru [Tomsk State University of Architecture and Building, Tomsk, 634002, Russia, Tomsk, 2 Solyanaya Sq (Russian Federation)

    2016-01-15

    The paper reports on the study where we analyzed the surface structure and strength properties of coated Al alloys modified by electron-ion plasma treatment. The Al alloys were deposited with a thin (≈0.5 μm) TiCu film coating (TiCu-Al system) and with a hard TiCuN coating (TiCuN–AlSi system) on a TRIO vacuum setup in the plasma of low-pressure arc discharges. The temperature fields and phase transformations in the film–substrate system were estimated by numerical simulation in a wide range of electron energy densities (5–30 J/cm{sup 2}) and pulse durations (50–200 μs). The calculations allowed us to determine the threshold energy density and pulse duration at which the surface structure of the irradiated Al-based systems is transformed in a single-phase state (solid or liquid) and in a two-phase state (solid plus liquid). The elemental composition, defect structure, phase state, and lattice state in the modified surface layers were examined by optical, scanning, and transmission electron microscopy, and by X-ray diffraction analysis. The mechanical characteristics of the modified layers were studied by measuring the hardness and Young’s modulus. The tribological properties of the modified layers were analyzed by measuring the wear resistance and friction coefficient. It is shown that melting and subsequent high-rate crystallization of the TiCu–Al system makes possible a multiphase Al-based surface structure with the following characteristics: crystallite size ranging within micrometer, microhardness of more than 3 times that in the specimen bulk, and wear resistance ≈1.8 times higher compared to the initial material. Electron beam irradiation of the TiCuN–AlSi system allows fusion of the coating into the substrate, thus increasing the wear resistance of the material ≈2.2 times at a surface hardness of ∼14 GPa.

  12. Electron-ion plasma modification of Al-based alloys

    International Nuclear Information System (INIS)

    The paper reports on the study where we analyzed the surface structure and strength properties of coated Al alloys modified by electron-ion plasma treatment. The Al alloys were deposited with a thin (≈0.5 μm) TiCu film coating (TiCu-Al system) and with a hard TiCuN coating (TiCuN–AlSi system) on a TRIO vacuum setup in the plasma of low-pressure arc discharges. The temperature fields and phase transformations in the film–substrate system were estimated by numerical simulation in a wide range of electron energy densities (5–30 J/cm2) and pulse durations (50–200 μs). The calculations allowed us to determine the threshold energy density and pulse duration at which the surface structure of the irradiated Al-based systems is transformed in a single-phase state (solid or liquid) and in a two-phase state (solid plus liquid). The elemental composition, defect structure, phase state, and lattice state in the modified surface layers were examined by optical, scanning, and transmission electron microscopy, and by X-ray diffraction analysis. The mechanical characteristics of the modified layers were studied by measuring the hardness and Young’s modulus. The tribological properties of the modified layers were analyzed by measuring the wear resistance and friction coefficient. It is shown that melting and subsequent high-rate crystallization of the TiCu–Al system makes possible a multiphase Al-based surface structure with the following characteristics: crystallite size ranging within micrometer, microhardness of more than 3 times that in the specimen bulk, and wear resistance ≈1.8 times higher compared to the initial material. Electron beam irradiation of the TiCuN–AlSi system allows fusion of the coating into the substrate, thus increasing the wear resistance of the material ≈2.2 times at a surface hardness of ∼14 GPa

  13. Factors affecting the optical properties of Pd-free Au-Pt-based dental alloys.

    Science.gov (United States)

    Shiraishi, Takanobu; Takuma, Yasuko; Miura, Eri; Tanaka, Yasuhiro; Hisatsune, Kunihiro

    2003-12-01

    The optical properties of experimental Au-Pt-based alloys containing a small amount of In, Sn, and Zn were investigated by spectrophotometric colorimetry to extract factors affecting color of Au-Pt-based high-karat dental alloys. It was found that the optical properties of Au-Pt-based alloys are strongly affected by the number of valence electrons per atom in an alloy, namely, the electron:atom ratio, e/a. That is, by increasing the e/a-value, activities of reflection in the long-wavelength range and absorption in the short-wavelength range in the visible spectrum apparently increased. As a result, the maximum slope of the spectral reflectance curve at the absorption edge, which is located near 515 nm (approximately 2.4 eV), apparently increased with e/a-value. Due to this effect, the b*-coordinate (yellow-blue) in the CIELAB color space considerably increased and the a*-coordinate (red-green) slightly increased with e/a-value. The addition of a third element with a higher number of valence electrons to the binary Au-Pt alloy is, therefore, effective in giving a gold tinge to the parent Au-Pt alloy. This information may be useful in controlling the color of Au-Pt-based dental alloys. PMID:15348493

  14. Shape Memory Alloy-Based Periodic Cellular Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II effort will continue to develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular...

  15. Damping and microstructures in aged Cu-Mn based alloys

    OpenAIRE

    Heil, Joseph Patrick.

    1988-01-01

    Approved for public release; distribution is unlimited An aged high damping alloy 53Cu 45Mn-2Al was studied both microstructurally by transmission electron microscopy (TEM) and microstructurally with two different damping measurement methods. In-situ heating and cooling observations were made with TEM in order to define the recently discovered flickering phenomenon associated with it's tweed microstructure. TEM studies were also made of an aged 53.6Cu-46.4Mn binary alloy. Damping measureme...

  16. Effects of copper-based alloy on the synthesis of single-crystal diamond

    CERN Document Server

    Chen Li Xue; Ma Hong An; Jia Xiao Peng; Wakatsuki, M; Zou Guang Tian

    2002-01-01

    The catalytic effects of copper-based alloys in diamond growth have been investigated. A single crystal of diamond has been obtained by the temperature gradient method (TGM), using Cu-Mn-Co and Cu-Co alloys as catalysts. It was found that the melted Cu-Mn-Co and Cu-Co alloys show low viscosity. The eutectic temperatures of these two alloys with graphite were between 1130 and 1150 deg. C, and the temperature of the transition to diamond was over 1300 deg. C at 5.5 GPa. High-quality diamond could not be obtained in Cu-Co alloy by the TGM. Our results suggest that adding Cu to a catalyst cannot decrease the reaction temperature for diamond growth.

  17. Modification of mechanical properties and microstructure of Ni-Cr-base alloy by continuous electron irradiation

    International Nuclear Information System (INIS)

    Using the methods of transmission and scanning electron microscopy and X-ray structure analysis investigation of 40CrNiAl alloy structure-phase state after different conditions of thermomechanical treatment (TMT) and electron irradiation is carried out. Correlation of microstructure parameters of irradiated alloy with its mechanical properties is ascertained as well as morphology of structural and phase transformations in alloy at continuous electron irradiation. Simultaneous increasing of strength characteristics and plasticity of 40CrNiAl alloy after certain conditions of TMT and electron irradiation is find out, the reasons of the phenomenon is analyzed. The scientifically-based schemes of 40CrNiAl alloy TMT are developed and choice of electron irradiation conditions for optimization of its mechanical properties is substantiated

  18. Oxidation induced phase transformations and lifetime limits of chromia forming nickel base alloy 625

    OpenAIRE

    Chyrkin, Anton

    2011-01-01

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of delta-Ni3Nb and (Ni,Mo,Si)6C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900–1000°C in oxidatio...

  19. Study on DC welding parameters of Al-alloy shaping based on arc-welding robot

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Al-alloy arc-welding shaping system based on arc-welding robot is established, and the Al-alloy shaping manufacture is realized with the DC (direct current) gas metal arc welding (GMAW). The research indicates that the metal transfer type of DC GMAW, heat input and the initial temperature of the workpiece greatly affect the Al-alloy shaping based on arc welding robot. On the penetration, the weld width and the reinforcement, the influence of welding parameters is analyzed by generalized regression neural network (GRNN) fitting.

  20. Neutron scattering measurements a useful alloy development tool for the new generation high temperature alloys based Co-Re system

    Czech Academy of Sciences Publication Activity Database

    Mukherji, D.; Wehr, J.; Strunz, Pavel; Gilles, R.; Hofmann, M.; Hoelzel, M.; Roesler, J.

    München : Technische Universität München, 2012 - (Carsughi, F.; Lommatzsch, I.; Neuhaus, J.). s. 34-34 [4th User Meeting at the FRM II. 23.03.2012-23.03.2012, Garching bei München] Institutional support: RVO:61389005 Keywords : Co-Re based alloys * neutron scattering * high temeperature Subject RIV: BM - Solid Matter Physics ; Magnetism http://cdn.frm2.tum.de/fileadmin/stuff/ information /UserOffice/UM2012_Booklet_lr.pdf

  1. Alloys based on Group 5 metals for hydrogen purification membranes

    International Nuclear Information System (INIS)

    Highlights: • The Ta77Nb23 alloy showed hydrogen permeability high enough to be used in diffusion purification technology. • The Ta77Nb23 alloy has mechanical properties suitable for practical application. • The hydrogen permeability data were acquired for the alloys with no special coatings. - Abstract: Production of high-purity hydrogen is required to move to power systems with little environmental impact. The considerable part of hydrogen is suggested to be obtained by methane conversion and its separation from other hydrocarbon gases which are not involved in the energy production process (associated gas, waste gas of petrochemical industry, etc.). The aim of this study was to compare properties of low cost alloys for membranes for hydrogen purification and separation. To investigate the membranes of V53Ti26Ni21 and Ta77Nb23 (wt.%) alloys, the specific hydrogen permeability and micro hardness tests, metallography and X-ray diffraction were applied. It was concluded the Ta77Nb23 (wt.%) alloy has hydrogen permeability parameters and mechanical characteristics that make it suitable for the production of thin membranes

  2. Alloys based on Group 5 metals for hydrogen purification membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kozhakhmetov, S. [Institute of High Technologies, 050012 Almaty (Kazakhstan); Sidorov, N. [Institute of Metallurgy UB RAS, 620016 Ekaterinburg (Russian Federation); Piven, V. [Saint Petersburg State University, 198504 Saint Petersburg (Russian Federation); Sipatov, I. [Institute of Metallurgy UB RAS, 620016 Ekaterinburg (Russian Federation); Gabis, I. [Saint Petersburg State University, 198504 Saint Petersburg (Russian Federation); Arinov, B. [Institute of High Technologies, 050012 Almaty (Kazakhstan)

    2015-10-05

    Highlights: • The Ta{sub 77}Nb{sub 23} alloy showed hydrogen permeability high enough to be used in diffusion purification technology. • The Ta{sub 77}Nb{sub 23} alloy has mechanical properties suitable for practical application. • The hydrogen permeability data were acquired for the alloys with no special coatings. - Abstract: Production of high-purity hydrogen is required to move to power systems with little environmental impact. The considerable part of hydrogen is suggested to be obtained by methane conversion and its separation from other hydrocarbon gases which are not involved in the energy production process (associated gas, waste gas of petrochemical industry, etc.). The aim of this study was to compare properties of low cost alloys for membranes for hydrogen purification and separation. To investigate the membranes of V{sub 53}Ti{sub 26}Ni{sub 21} and Ta{sub 77}Nb{sub 23} (wt.%) alloys, the specific hydrogen permeability and micro hardness tests, metallography and X-ray diffraction were applied. It was concluded the Ta{sub 77}Nb{sub 23} (wt.%) alloy has hydrogen permeability parameters and mechanical characteristics that make it suitable for the production of thin membranes.

  3. Transport phenomena in nanowires based on bismuth alloys

    International Nuclear Information System (INIS)

    Full text: In this work, we study the conductivity and thermopower of quantum wires (QW) based on bismuth alloys. Calculations are carried out for nanowires with degenerate and nondegenerate gas of carriers at various crystalline orientations taking into account the real band structure of Bi. We find the energy eigenvalues of holes and taking into account the nonparabolicity of the band, the energy eigenvalues for electrons. The conductivity and thermopower determined with the use of the Kubo formulae in the case when the basic mechanism of carrier scattering is assumed to be elastic acoustic-phonon scattering and on a roughness surface of QW. Dependences of kinetic coefficients on temperature, nanowire diameter and crystalline orientation are investigated. The conductivity and thermopower of a QW contains the contributions of electrons and holes. Taking into account values of carrier effective masses and other band parameters of Bi, it is possible to conclude that the contribution of holes to the conductivity of nondegenerate carriers of QWs is more less than that of electrons, which is attributed to smaller effective mass of electrons. For a semiconducting Bi QW the conductivity depends exponentially on a temperature and wire diameter. The thermopower of a semiconducting and of a semimetallic Bi QW at low temperatures can be positive and change sign in more higher temperatures. The theoretical results are close to experiment for Bi wires with diameter of 50-100 nm. (author)

  4. Deployable aerospace PV array based on amorphous silicon alloys

    Science.gov (United States)

    Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

    1989-01-01

    The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

  5. Shape-Memory-Alloy-Based Deicing System Developed

    Science.gov (United States)

    1996-01-01

    Ice buildup on aircraft leading edge surfaces has historically been a problem. Most conventional deicing systems rely either on surface heating to melt the accreted ice or pneumatic surface inflation to mechanically debond the ice. Deicers that rely solely on surface heating require large amounts of power. Pneumatic deicers usually cannot remove thin layers of ice and lack durability. Thus, there is a need for an advanced, low-power ice protection system. As part of the NASA Small Business and Innovation Research (SBIR) program, Innovative Dynamics, Inc., developed an aircraft deicing system that utilizes the properties of Shape Memory Alloys (SMA). The SMA-based system has achieved promising improvements in energy efficiency and durability over more conventional deicers. When they are thermally activated, SMA materials change shape; this is analogous to a conventional thermal expansion. The thermal input is currently applied via conventional technology, but there are plans to implement a passive thermal input that is supplied from the energy transfer due to the formation of the ice itself. The actively powered deicer was tested in the NASA Lewis Icing Research Tunnel on a powered rotating rig in early 1995. The system showed promise, deicing both rime and glaze ice shapes as thin as 1/8 in. The first prototype SMA deicer reduced power usage by 45 percent over existing electrothermal systems. This prototype system was targeted for rotorcraft system development. However, there are current plans underway to develop a fixed-wing version of the deicer.

  6. Shape Memory Alloy (SMA)-Based Launch Lock

    Science.gov (United States)

    Badescu, Mircea; Bao, Xiaoqi; Bar-Cohen, Yoseph

    2014-01-01

    Most NASA missions require the use of a launch lock for securing moving components during the launch or securing the payload before release. A launch lock is a device used to prevent unwanted motion and secure the controlled components. The current launch locks are based on pyrotechnic, electro mechanically or NiTi driven pin pullers and they are mostly one time use mechanisms that are usually bulky and involve a relatively high mass. Generally, the use of piezoelectric actuation provides high precession nanometer accuracy but it relies on friction to generate displacement. During launch, the generated vibrations can release the normal force between the actuator components allowing shaft's free motion which could result in damage to the actuated structures or instruments. This problem is common to other linear actuators that consist of a ball screw mechanism. The authors are exploring the development of a novel launch lock mechanism that is activated by a shape memory alloy (SMA) material ring, a rigid element and an SMA ring holding flexure. The proposed design and analytical model will be described and discussed in this paper.

  7. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-08-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10, and iron = 83.71. The cast ingots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot- worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  8. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  9. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    International Nuclear Information System (INIS)

    The aim of this study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. According to our study, the salient features for the ternary alloy are a negative SRO parameter between Ni–Cr and a positive between Cr–Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni–Cr and Ni–Fe pairs and positive for Cr–Cr and Fe–Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. The predicted SRO has an impact on point-defect energetics, electron–phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys

  10. Advanced oxidation-resistant iron-based alloys for LWR fuel cladding

    Science.gov (United States)

    Terrani, K. A.; Zinkle, S. J.; Snead, L. L.

    2014-05-01

    Application of advanced oxidation-resistant iron alloys as light water reactor fuel cladding is proposed. The motivations are based on specific limitations associated with zirconium alloys, currently used as fuel cladding, under design-basis and beyond-design-basis accident scenarios. Using a simplified methodology, gains in safety margins under severe accidents upon transition to advanced oxidation-resistant iron alloys as fuel cladding are showcased. Oxidation behavior, mechanical properties, and irradiation effects of advanced iron alloys are briefly reviewed and compared to zirconium alloys as well as historic austenitic stainless steel cladding materials. Neutronic characteristics of iron-alloy-clad fuel bundles are determined and fed into a simple economic model to estimate the impact on nuclear electricity production cost. Prior experience with steel cladding is combined with the current understanding of the mechanical properties and irradiation behavior of advanced iron alloys to identify a combination of cladding thickness reduction and fuel enrichment increase (∼0.5%) as an efficient route to offset any penalties in cycle length, due to higher neutron absorption in the iron alloy cladding, with modest impact on the economics.

  11. Thermodynamic Prediction of Compositional Phases Confirmed by Transmission Electron Microscopy on Tantalum-Based Alloy Weldments

    International Nuclear Information System (INIS)

    Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for radioisotope based thermal to electrical power systems since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. Tantalum alloys have demonstrated sufficient high-temperature toughness to survive prolonged exposure to the radioisotope power-system working environment. Typically, the fabrication of power systems requires the welding of various components including the structural members made of tantalum alloys. Issues such as thermodynamics, lattice structure, weld pool dynamics, material purity and contamination, and welding atmosphere purity all potentially confound the understanding of the differences between the weldment properties of the different tantalum-based alloys. The objective of this paper is to outline the thermodynamically favorable material phases in tantalum alloys, with and without small amounts of hafnium, during and following solidification, based on the results derived from the FactSage(c) Integrated Thermodynamic Databank. In addition, Transition Electron Microscopy (TEM) data will show for the first time, the changes occurring in the HfC before and after welding, and the data will elucidate the role HfC plays in pinning grain boundaries

  12. Aluminium Alloy-Based Metal Matrix Composites: A Potential Material for Wear Resistant Applications

    OpenAIRE

    Rupa Dasgupta

    2012-01-01

    Aluminium alloy-based metal matrix composites (AMMCs) have been by now established themselves as a suitable wear resistant material especially for sliding wear applications. However, in actual practice engineering components usually encounter combination of wear types. An attempt has been made in the present paper to highlight the effect of dispersing SiC in 2014 base alloy adopting the liquid metallurgy route on different wear modes like sliding, abrasion, erosion, and combinations of wear m...

  13. Single-crystal tungsten-based alloys with molybdenum and rhenium

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Single crystals of ternary W-based alloys with 2 % Re and less than 7 % Mo have been grown for the first time at the Baikov Institute of Metallurgy and Materials Science RAS. Plasma arc melting allowed us to effectively purify the single crystals from a number of impurities. According to mass spectrometric analysis for 70 elements, the total content of impurities does not exceed 0. 063%. It was found that, as the Mo content increases, the size of first-kind subgrains decreases and their mutual misorientation increases. In the W-based alloy with 2.3 % Re and 6.7% Mo, no first-kind subgrains are observed,whereas second-kind subgrains are elongated along the growth direction. In this case, their total misorientation is well below that in the other low-alloy single crystals.Single-crystal of binary tungsten-based alloys with rhenium were prepared by electron-beam zone melting (1% Re, mass fraction) and plasma arc melting (2%Re, 10%Re, 25%Re (mass fraction)). It was found that the low-alloyed (1%-2 % Rh (mass fraction)) W-based alloys are characterized by a rather perfect single-crystal structure and misorientations of first- and second-kind subgrains of 20-50' and 10-40', respectively. Sections with the coarse-grained structure are observed in ingots of the alloy with 10%and 25% (mass fraction) Rh; in the alloy with 25% Rh, such structure is observed immediately from the seed.A device for measuring the liquidus and solidus temperatures of refractory metallic alloys has been designed. The liquidus temperatures of ternary single crystals (W-Mo-Re) have been measured.The studied single crystals, owing to their purity and high stability of the structure and properties,are widely used in electronics, electrical engineering, and analytical devices for various purposes.

  14. Ultra-low temperature processing of barium tellurate dielectrics

    Science.gov (United States)

    Kwon, Do-Kyun

    . Co-firing studies of barium tellurate ceramics with metal electrodes establish new LTCC systems for microwave devices. Chemical compatibility of barium tellurates with silver electrodes was achieved in the barium rich compositions. Ba2TeO5 was found to be covetable with silver electrodes at 850°C by adding CuO and B2O3 as fluxing agents. During the co-firing, a thin interfacial layer of AgTe is metastable according to the thermodynamic equilibrium between the Ba2TeO5-Ag/Ag 2O pseudo-binary system. A breakthrough LTCC technology with aluminum is based upon the ultra-low processing temperature and chemical compatibility of BaTe4O 9, which enables co-firing and fabrication of multilayer ceramic capacitors (MLCCs) with aluminum inner electrodes. The aluminum base metal electrode (BME) BaTe4O9 MLCCs provide good dielectric properties of epsilonr = 17.5, TCepsilon = 100 ppm/°C, and tan delta = 2.1 x 10-3 (Q ≈ 500) at 1 MHz, which are suitable for the class-1 MLCCs. Aluminum microstrip ring resonators on the BaTe4O9 substrates realized good electromagnetic performance of the new materials at microwave frequency exhibiting resonant frequency of 2.97 GHz and Q factor of 278.

  15. Survey of BGFA Criteria for the Cu-Based Bulk Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    D. Janovszky

    2011-01-01

    Full Text Available To verify the effect of composition on the bulk glass forming ability (BGFA of Cu-based alloys, properties have been collected from the literature (~100 papers, more than 200 alloys. Surveying the BGFA criteria published so far, it has been found that the atomic mismatch condition of Egami-Waseda is fulfilled for all the Cu-based BGFAs, the value being above 0,3. The Zhang Bangwei criterion could be applied for the binary Cu-based alloys. The Miracle and Senkov criteria do not necessarily apply for Cu based bulk amorphous alloys. The critical thickness versus =/(+ plot of Lu and Liu extrapolates to =0.36, somewhat higher than the 0.33 value found in other BGFA alloys. The Park and Kim parameter correlates rather poorly with the critical thickness for Cu based alloys. The Cheney and Vecchino parameter is a good indicator to find the best glass former if it is possible to calculate the exact liquids projection. In 2009 Xiu-lin and Pan defined a new parameter which correlates a bit better with the critical thickness. Based on this survey it is still very difficult to find one parameter in order to characterize the real GFA without an unrealized mechanism of crystallization.

  16. Effect of alloying on elastic properties of ZrN based transition metal nitride alloys

    KAUST Repository

    Kanoun, Mohammed

    2014-09-01

    We report the effect of composition and metal sublattice substitutional element on the structural, elastic and electronic properties of ternary transition metal nitrides Zr1-xMxN with M=Al, Ti, Hf, V, Nb, W and Mo. The analysis of the elastic constants, bulk modulus, shear modulus, Young\\'s modulus, and Poisson\\'s ratio provides insights regarding the mechanical behavior of Zr1-xMxN. We predict that ternary alloys are more ductile compared to their parent binary compounds. The revealed trend in the mechanical behavior might help for experimentalists on the ability of tuning the mechanical properties during the alloying process by varying the concentration of the transition metal. © 2014 Elsevier B.V.

  17. Barium methylphosphonates: synthesis, characterization and mutual interconversions

    Czech Academy of Sciences Publication Activity Database

    Beneš, L.; Melánová, Klára; Svoboda, Jan; Zima, Vítězslav

    Strasbourg: University of Strasbourg, Francie, 2015. P64. [ISIC18 International Symposium on Intercalation Compounds. 31.05.2015-04.06.2015, Strasbourg] R&D Projects: GA ČR(CZ) GA14-13368S Institutional support: RVO:61389013 Keywords : hydrates of barium methylphosphonate * barium hydrogen methylphosphonate * powder X-ray diffraction Subject RIV: CA - Inorganic Chemistry

  18. Shape memory alloy wire-based smart natural rubber bearing

    International Nuclear Information System (INIS)

    In this study, two types of smart elastomeric bearings are presented using shape memory alloy (SMA) wires. Due to the unique characteristics of SMAs, such as the superelastic effect and the recentering capability, the residual deformation in SMA-based natural rubber bearings (SMA-NRBs) is significantly reduced whereas the energy dissipation capacity is increased. Two different configurations of SMA wires incorporated in elastomeric bearings are considered. The effect of several parameters, including the shear strain amplitude, the type of SMA, the aspect ratio of the base isolator, the thickness of SMA wire, and the amount of pre-strain in the wires on the performance of SMA-NRBs is investigated. Rubber bearings are composed of natural rubber layers bonded to steel shims as reinforcement. Results show that ferrous SMA wire, FeNiCuAlTaB, with 13.5% superelastic strain and a very low austenite finish temperature (−62 °C), is the best candidate to be used in SMA-NRBs subjected to high shear strain amplitudes. In terms of the lateral flexibility and wire strain level, the smart rubber bearing with a cross configuration of SMA wires is more efficient. Moreover, the cross configuration can be implemented in high-aspect-ratio elastomeric bearings since the strain induced in the wire does not exceed the superelastic range. When cross SMA wires with 2% pre-strain are used in a smart NRB, the dissipated energy is increased by 74% and the residual deformation is decreased by 15%. (paper)

  19. The metallographic investigation of brazed joints in nickel base alloys using various techniques for the production of contrast

    International Nuclear Information System (INIS)

    Brazing with high melting point nickel base brazing alloys permits distortion-free, high strength joints to be produced in high temperature, high alloy steel and nickel alloys which cannot easily be welded. This method is used for gas turbine parts subject to high thermal stresses and in nuclear engineering. (orig.)

  20. Rational design of Nb-based alloys for hydrogen separation: A first principles study

    Directory of Open Access Journals (Sweden)

    Byungki Ryu

    2013-02-01

    Full Text Available We have investigated the effect of alloying metal elements on hydrogen solubility and mechanical integrity of Nb-based alloys, Nb15M1 (where M = Ca–Zn, Ge, using first principles-based calculations. In general, the chemical interaction between the interstitial H and metal is weakened as the alloying element is changed from an early to a late transition metal, leading to lower H solubility and higher resistance to H embrittlement. This effect becomes more pronounced when a smaller alloying element is used due to stronger elastic interaction between interstitial H and metal atoms. These finding may provide scientific basis for rational design of Nb-based hydrogen separation membranes with tailored H solubility to effectively suppress H embrittlement while maintaining excellent hydrogen permeation rate.

  1. Dry sliding wear characteristics of rheocast Mg–Sn based alloys

    International Nuclear Information System (INIS)

    Highlights: • Studied wear behavior of rheocast Mg–Sn based alloys under ambient temperature. • The volumetric wear was found to be increased with increasing applied load. • Different wear micro-mechanism was observed under electron micro-scope. • Plastic deformation and work hardening took place for all the alloys mainly at the higher loads. - Abstract: Present paper focuses on the dry sliding wear behavior of rheocast Mg–Sn based alloys under ambient temperature. The alloys were studied through pin-on-disc wear experiments under four different loading conditions, namely, 9.8, 19.6, 29.4 and 39.2 N. Present investigations highlight the influence of load on the cumulative wear loss, volumetric wear loss, dry sliding wear rate and co-efficient of friction of the different alloys under study. The volumetric wear was found to be increased with increasing applied load. Different wear micro-mechanisms were observed under electron micro-scope. The wear occurs mainly by ploughing mechanism and by delamination also. During wear, extensive plastic deformation and work hardening took place for all the alloys mainly at the higher loads. Micro-structural analysis has been performed for all the alloys at different loading conditions

  2. Hot Workability of CuZr-Based Shape Memory Alloys for Potential High-Temperature Applications

    Science.gov (United States)

    Biffi, Carlo Alberto; Tuissi, Ausonio

    2014-07-01

    The research on high-temperature shape memory alloys has been growing because of the interest of several potential industrial fields, such as automotive, aerospace, mechanical, and control systems. One suitable candidate is given by the CuZr system, because of its relative low price in comparison with others, like the NiTi-based one. In this context, the goal of this work is the study of hot workability of some CuZr-based shape memory alloys. In particular, this study addresses on the effect of hot rolling process on the metallurgical and calorimetric properties of the CuZr system. The addition of some alloying elements (Cr, Co, Ni, and Ti) is taken into account and their effect is also put in comparison with each other. The alloys were produced by means of an arc melting furnace in inert atmosphere under the shape of cigars. Due to the high reactivity of these alloys at high temperature, the cigars were sealed in a stainless steel can before the processing and two different procedures of hot rolling were tested. The characterization of the rolled alloys is performed using discrete scanning calorimetry in terms of evolution of the martensitic transformation and scanning electron microscopy for the microstructural investigations. Additionally, preliminary tests of laser interaction has been also proposed on the alloy more interesting for potential applications, characterized by high transformation temperatures and its good thermal stability.

  3. Investigation of the isothermal precipitation behaviour of nickel-base alloys using electrochemical phase extraction

    International Nuclear Information System (INIS)

    Electrochemical phase extraction methods have been developed empirically for the selective separation of the precipitates in metallic materials. A detailed description of the process has been undertaken to allow optimization for various nickel-base alloys. For this part of the investigation, 16 model alloys were prepared as test electrodes and the electrolyte composition was varied over a wide range. The results enabled a series of effects to be explained on the basis of electrochemical data. The large number of test parameters limited the scope of the preliminary experiments and the range of model alloys used. In the nickel-base alloys, titanium carbo-nitride and primary M6C precipitates were identified. During isothermal ageing, M23C6 (except in Alloy KSN), Ni3Al (in INCONEL 617), Laves phases (in Hastelloy X and INCONEL 617), M12C (in HASTELLOY X and INCONEL 617) and α-tungsten (in the tungsten-containing alloys) were precipitated. The precipitation behaviour changed in the alloys investigated from intracrystalline to intercrystalline with increasing ageing temperature. The intracrystalline secondary precipitations affect the microhardness, structure and the solid-solution lattice. (orig.)

  4. Biocompatibility of new Ti-Nb-Ta base alloys.

    Science.gov (United States)

    Hussein, Abdelrahman H; Gepreel, Mohamed A-H; Gouda, Mohamed K; Hefnawy, Ahmad M; Kandil, Sherif H

    2016-04-01

    β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti77Nb17Ta6) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Young's modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti-6Al-4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity. PMID:26838885

  5. Chemical abundance analysis of 19 barium stars

    CERN Document Server

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  6. Barium hexaferrite ferrofluids - preparation and physical properties

    Science.gov (United States)

    Müller, R.; Hiergeist, R.; Steinmetz, H.; Ayoub, N.; Fujisaki, M.; Schüppel, W.

    1999-07-01

    Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared for the first time using oleic acid as surfactant and Isopar M ® as carrier liquid. The initial susceptibility versus temperature for zero-field cooling of the ferrofluid was obtained by a vibrating sample magnetometer. TEM pictures of the fluid show isolated particles and only small agglomerates and a mean particle diameter of approx. 8 nm. Numerical calculations of the magneto-viscous effect, based on the local-equilibrium magnetic state model, clearly show the benefit for Ba-ferrite ferrofluids resulting from the high uniaxial anisotropy compared to magnetite ferrofluids. Rheological measurements were performed with a rotational-type viscometer with magnetic field perpendicular to the hydrodynamic vortex axis.

  7. Interstitial-phase precipitation in iron-base alloys: a comparative study

    International Nuclear Information System (INIS)

    Recent developments have elucidated the atomistic mechanisms of precipitation of interstitial elements in simple alloy systems. However, in the more technologically important iron base alloys, interstitial phase precipitation is generally not well understood. The present experimental study was therefore designed to test the applicability of these concepts to more complex ferrous alloys. Hence, a comparative study was made of interstitial phase precipitation in ferritic Fe-Si-C and in austenitic phosphorus-containing Fe-Cr-Ni steels. These systems were subjected to a variety of quench-age thermal treatments, and the microstructural development was subsequently characterized by transmission electron microscopy

  8. Application of feal intermetallic phase matrix based alloys in the turbine components of a turbocharger

    OpenAIRE

    J. Cebulski

    2015-01-01

    This paper presents a possible application of the state-of-the-art alloys based on the FeAl intermetallic phases as materials for the manufacture of heat-proof turbine components in an automobile turbocharger. The research was aimed at determining the resistance to corrosion of Fe40Al5CrTiB alloy in a gaseous environment containing 9 % O2 + 0,2 % HCl + 0,08 % SO2 + N2. First the kinetics of corrosion processes for the considered alloy were determined at the temperatures of 900 °C, 1 000 °C an...

  9. Mechanical Responses of Superlight β-Based Mg-Li-Al-Zn Wrought Alloys under Resonance

    Science.gov (United States)

    Song, Jenn-Ming; Lin, Yi-Hua; Su, Chien-Wei; Wang, Jian-Yih

    2009-05-01

    To extend the application of lightweight Mg alloys in the automotive industry, this study suggests a β-based Mg-Li alloy (LAZ1110) with superior vibration fracture resistance by means of material design. In the cold-rolled state, a strengthened β matrix by the additions of Al and Zn, as well as intergranular platelike α precipitates, which are able to stunt the crack growth, contributes to a comparable vibration life with commercial Mg-Al-Zn alloys under a similar strain condition.

  10. Thermo-physical properties and phase transformation behavior of thorium-based alloys and oxides

    International Nuclear Information System (INIS)

    In this presentation, the results of classical molecular dynamics (CMD) simulations of lattice thermal expansion (LTE), elastic constants and thermal conductivity of Urania-Thoria, Thoria-Ceria/Plutonia MOX fuels will be presented along with some experimental results using high temperature X-ray diffraction techniques. At the same time, it is very useful to understand the possible phase transformations in Th bases metallic alloys with a view to identify the metastable phases. This aspect is important from phase stability point of view. All these metallic alloys shows phase separation tendencies and complex compound formation. This presentation also discusses the nature of phase transformations in these alloys involving stable and metastable phases

  11. Investigations of carbon diffusion and carbide formation in nickel-based alloys

    International Nuclear Information System (INIS)

    The present thesis describes the carburization behaviour of nickel based alloys in heavily carburizing environments. The mechanisms of carbon diffusion and carbide precipitation in NiCr alloys with and without ternary additions of iron, cobalt or molybdenum have been investigated. Using the results of carburization experiments, a mathematical model which describes carbon diffusion and carbide formation, was developed. The simulation of the carburization process was carried out by an iterative calculation of the local thermodynamic equilibrium in the alloy. An accurate description of the carbon profiles as a function of time became possible by using a finite-difference calculation. (orig.)

  12. Solute partitioning and site preference in γ/γ′ cobalt-base alloys

    International Nuclear Information System (INIS)

    This paper reports three-dimensional atom probe tomography results from a γ/γ′ based Co–Al–W alloy and two quaternary variants of this alloy highlighting the following salient features: (i) sub-nanometer-scale solute partitioning across the γ/γ′ interface as well as solute pile-up at this interface; (ii) the site preference of quaternary elements in γ′ precipitates, Co3(Al, W); and (iii) formation of multiple generations of γ′ precipitates in one of the alloys.

  13. Ferroelectric/Dielectric Double Gate Insulator Spin-Coated Using Barium Titanate Nanocrystals for an Indium Oxide Nanocrystal-Based Thin-Film Transistor.

    Science.gov (United States)

    Pham, Hien Thu; Yang, Jin Ho; Lee, Don-Sung; Lee, Byoung Hun; Jeong, Hyun-Dam

    2016-03-23

    Barium titanate nanocrystals (BT NCs) were prepared under solvothermal conditions at 200 °C for 24 h. The shape of the BT NCs was tuned from nanodot to nanocube upon changing the polarity of the alcohol solvent, varying the nanosize in the range of 14-22 nm. Oleic acid-passivated NCs showed good solubility in a nonpolar solvent. The effect of size and shape of the BT NCs on the ferroelectric properties was also studied. The maximum polarization value of 7.2 μC/cm(2) was obtained for the BT-5 NC thin film. Dielectric measurements of the films showed comparable dielectric constant values of BT NCs over 1-100 kHz without significant loss. Furthermore, the bottom gate In2O3 NC thin film transistors exhibited outstanding device performance with a field-effect mobility of 11.1 cm(2) V(-1) s(-1) at a low applied gate voltage with BT-5 NC/SiO2 as the gate dielectric. The low-density trapped state was observed at the interface between the In2O3 NC semiconductor and the BT-5 NCs/SiO2 dielectric film. Furthermore, compensation of the applied gate field by an electric dipole-induced dipole field within the BT-5 NC film was also observed. PMID:26927618

  14. Performance evaluation of vitrified waste product based on barium-borosilicate matrix deployed for vitrification of sulphate bearing high level radioactive liquid waste

    International Nuclear Information System (INIS)

    Aqueous waste of various categories (viz., low, intermediate and high level depending on the concentration of radionuclides) is generated at different stages of the nuclear fuel cycle. Most of the radioactivity generated in entire nuclear fuel cycle is concentrated in high level radioactive liquid waste (HLW). Since the radioactivity of the waste is to be isolated from the human-environment for extended period of time, a three stage approach has been adopted for management of HLW. This involves (i) immobilization of waste oxides in stable and inert solid matrices, (ii) interim retrievable storage of conditioned waste packages under cooling and surveillance and (iii) deep underground disposal in suitable geological formulations. Composition of HLW depends on various factors like type of fuel and its cladding, off reactor cooling, reprocessing flow sheet etc. Compositional changes in HLW necessitate modification in glass formulations, so as to get the conditioned product of desired characteristics. This report describes the experimental studies and results obtained for performance evaluation of the vitrified waste product made from barium borosilicate glass matrix accommodating sulphate bearing chemically simulated HLW. Product characteristics like chemical durability, homogeneity, phase separation, thermal conductivity, impact strength etc have been evaluated and discussed in the report. (author)

  15. Atom probe analysis of Sn in Zr-based alloys

    International Nuclear Information System (INIS)

    We have extensively used atom-probe field ion microscopy (APFIM) for microanalyses of a heat-treated Zircaloy-4 and Zr-Sn alloys containing 0.6 or 1.39 wt% Sn and clarified as to whether Sn is fully dissolved or not in the α-Zr matrix. It is found that Sn dissolves in the matrix of both Zircaloy-4 and Zr-0.6 wt% Sn alloy upon annealing at 723 K. For Zr-1.39 wt% Sn alloy, after annealing for more than 200 h, the symptom of phase separation has been found. The distribution of Sn in the matrix is changed from the α-quenched state, and local regions enriched with Sn are formed in the matrix. (orig.)

  16. Local atomic ordering in nickel based Ir and Rh alloys

    International Nuclear Information System (INIS)

    Experimental measurements of the diffuse X-ray scattering are performed on alloys of Ni with Rh and Ir. The atomic short range order (SRO) parameters αsub(i) are calculated from the measured intensity. The existence of SRO is established in the two systems. The values of α1 are observed to have anomalously large negative values for all the samples. The experimental data so obtained is interpreted theoretically by calculating the interaction energies on the basis of electronic theory of ordering. Theoretically calculated values of interaction energies are found to be in agreement with the experimentally determined type of order in these alloys. (author)

  17. Martensitic transformation in Co-based ferromagnetic shape memory alloy

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Yokaichiya, F.; Laufek, F.; Jarošová, Markéta; Jurek, Karel; Drahokoupil, Jan; Sedláková-Ignácová, Silvia; Molnár, Peter; Heczko, Oleg

    2012-01-01

    Roč. 122, č. 3 (2012), s. 475-477. ISSN 0587-4246. [International Symposium on Physics of Materials, ISPMA /12./. Praha, 04.09.2011-08.09.2011] R&D Projects: GA ČR(CZ) GA101/09/0702; GA ČR GAP107/10/0824; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : microstructure * shape memory alloy s * neutron diffraction * cobalt alloy s Subject RIV: JG - Metallurgy Impact factor: 0.531, year: 2012

  18. Mechanical strenght and niobium and niobium-base alloys substructures

    International Nuclear Information System (INIS)

    Niobium and some of its alloys have been used in several fields of technological applications such as the aerospace, chemical and nuclear industries. This is due to its excelent mechanical stringth at high temperatures and reasonable ductility at low temperatures. In this work, we review the main features of the relationship mechanical strength - substructure in niobium and its alloys, taking into account the presence of impurities, the influence of initial thermal and thermo - mechanical treatments as well as the irradiation by energetic particles. (Author)

  19. Undercooling and demixing of copper-based alloys

    DEFF Research Database (Denmark)

    Kolbe, M.; Brillo, J.; Egry, I.; Herlach, D.M.; Ratke, L.; Chatain, D.; Tinet, N.; Antion, C.; Battezzati, L.; Curiotto, S.; Johnson, E.; Pryds, Nini

    Since the beginning of materials science research under microgravity conditions immiscible alloys have been an interesting subject. New possibilities to investigate such systems are offered by containerless processing techniques. Of particular interest is the ternary system Cu-Fe-Co, and its...... limiting binaries, Cu-Co and Cu-Fe. They all show a metastable miscibility gap in the regime of the undercooled melt. Within the ESA-MAP project “CoolCop”, different aspects of this alloy have been investigated; results obtained so far are reported here....

  20. Corrosion properties of high silicon iron-based alloys in nitric acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of copper and rare-earth elements on corrosion behavior of ~iigh silicon iron-based alloys in nitric acid was studied by means of static and loading current corrosion experiments. The anodic polarization curve was also made to discuss the corrosion mechanism. The examination on alloy microstructure and SEM corrosion pattern showed that when silicon content reached 14.5%, the Fe3Si phase appeared and the primary structure of the iron-base alloy was ferrite. When adding 4.57% copper in the iron alloy, its corrosion resistance in static diluted sulfuric acid was improved while its corrosion resistance and electrochemical corrosion properties in the nitric acid were decreased. In contrast, the addition of rare earth elements could improve the corrosion properties in all above conditions including in static diluted sulfuric acid and in nitric acid.

  1. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P. [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J. [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  2. Atomic site location by channelling enhanced microanalysis (ALCHEMI) in γ'-strengthened Ni- and Pt-base alloys

    International Nuclear Information System (INIS)

    The additions of alloying elements to Ni- and Pt-base alloys influence the microstructure and thereby the creep properties, whereas the mechanism is uncertain. Therefore atomic site location by channelling enhanced microanalysis (ALCHEMI) was used to determine the site partitioning of ternary and quaternary alloying elements in the L12-ordered γ'-phase. Two ternary Ni-Al alloys with Cr and Ti additions were investigated. The measured site partitioning showed that Cr and Ti atoms prefer the Al-sublattice sites. For a ternary Pt-Al-Cr alloy, it was found that Cr atoms occupy Al sites. The influence of Ni as a fourth alloying element in a Pt-Al-Cr-Ni alloy on the site partitioning was also investigated. The detected results give evidence that in the quaternary alloy Cr and Ni atoms prefer the Pt sublattice. First principles calculations were used to support the experimental data

  3. Burner Rig Hot Corrosion of Five Ni-Base Alloys Including Mar-M247

    Science.gov (United States)

    Nesbitt, James A.; Helmink, R.; Harris, K.; Erickson, G.

    2000-01-01

    The hot corrosion resistance of four new Ni-base superalloys was compared to that of Mar-M247 by testing in a Mach 0.3 burner rig at 900 C for 300 1-hr cycles. While the Al content was held the same as in the Mar-M247, the Cr and Co levels in the four new alloys were decreased while other strengthening elements (Re, Ta) were increased. Surprisingly, despite their lower Cr and Co contents, the hot corrosion behavior of all four new alloys was superior to that of the Mar-M247 alloy. The Mar-M247 alloy began to lose weight almost immediately whereas the other four alloys appeared to undergo an incubation period of 50-150 1-hr cycles. Examination of the cross-sectional microstructures showed regions of rampant corrosion attack (propagation stage) in all five alloys after 300 1-hr cycles . This rampant corrosion morphology was similar for each of the alloys with Ni and Cr sulfides located in an inner subscale region. The morphology of the attack suggests a classic "Type I", or high temperature, hot corrosion attack.

  4. Atmospheric Corrosion of Different Fe-based Alloys in Nanocrystalline State

    Science.gov (United States)

    Sitek, J.; Sedlačková, K.; Seberíni, M.

    2005-07-01

    Nanocrystalline Fe-based alloys are interesting for their soft magnetic properties. Because these alloys are potentially applicable in outdoor-working components, their corrosion behaviour requires careful analysis. This work presents the results of the atmospheric corrosion tests in industrial and rural environments performed for up to 6 months. We compared the corrosion behaviour of two different compositions of NANOPERM-type alloys: Fe87.5Zr6.5B6 and Fe76Mo8Cu1B15 with classical FINEMET alloys of the nominal composition of Fe73.5Cu1Nb3Si13.5B9 type. The techniques of Mössbauer spectroscopy, conversion electron Mössbauer spectroscopy, X-ray diffraction and transmission electron microscopy have been employed to compare their corrosion rate, characterize corrosion products and inspect the structural changes of the nanocrystalline structure. It was found that the Si-containing FINEMET alloys are the most corrosion-resistant whereas worse corrosion properties were observed for molybdenum-containing Fe76Mo8Cu1B15 alloy. The corrosion product formed on the surface of NANOPERM-type alloys showed a needlelike morphology and a poor crystalline order and has been identified as lepidocrocite, γ-FeOOH.

  5. Microstructural observations of the crystallization of amorphous Fe-Si-B based magnetic alloys

    International Nuclear Information System (INIS)

    The effect of Cu and Nb alloying additions on the crystallization of Fe-Si-B based alloys were studied. DSC, XRD, TEM, EELS and VSM techniques were used to study the thermal properties, phase formation during primary crystallization, morphological transitions and magnetic properties. The additions of individual Cu or Nb alloying additions changed the crystallization temperature as well as the activation energy for primary crystallization. The phases formed during primary crystallization for the Fe77.5Si13.5B9, Fe76.5Si13.5B9Cu1 and Fe74.5Si13.5B9Nb3Cu1 alloys are the same, however the morphologies are significantly different. Alloying additions of 3 at.% Nb induced a change in the crystallization mechanism and the type of phases formed. The combined additions of Cu and Nb resulted in the formation of nanocrystals. B atoms were found to be rejected around dendrites formed during primary crystallization of the Fe77.5Si13.5B9 alloy. The highest saturation magnetization and the lowest coercivity is obtained in the Fe77.5Si13.5B9 and Fe74.5Si13.5B9Nb3Cu1 alloy respectively after annealing at 550 deg. C for 1 h

  6. The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells

    OpenAIRE

    Ahmad Agha, Nezha; Willumeit-Römer, Regine; Laipple, Daniel; Luthringer, Bérengère; Feyerabend, Frank

    2016-01-01

    Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Se...

  7. Formation Mechanism of Curved Martensite Structures in Cu-based Shape Memory Alloys

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The curved martensite structures have been observed in CuZnAl-based shape memory alloys by both transmission electron microscope and optical microscope. It was found that the curved martensite structures observed in as-solution treated, as-aged and as-trained alloys usually occurred around dislocation tangles or precipitate, at the plate boundary or grain boundary, and when the growing plates collided with each other or alternate mutually.

  8. RESIDUAL STRESS IN NICKEL BASE SUPER ALLOY UDIMET 720 FOR DIFFERENT SURFACE CONDITIONS

    OpenAIRE

    B.R.SRIDHAR,; S.RAMACHANDRA,; U.CHANDRASEKAR

    2011-01-01

    Nickel base super alloy Udimet 720 finds applications in gas turbine engine components like discs, shafts and blades. These components rotate at high speeds in a gas turbine engine and consequently experience both high cycle fatigue (HCF) and low cycle fatigue (LCF) due to dynamic loads and temperatures. Since residual stress affects both HCF and LCF properties, study of residual stress for varying surface conditions for this alloy assumes significance. Specimens extracted from a forging were...

  9. Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys

    Science.gov (United States)

    Miller, Robert A. (Inventor); Doychak, Joseph (Inventor)

    1994-01-01

    A thermal barrier coating system consists of two layers of a zirconia-yttria ceramic. The first layer is applied by low pressure plasma spraying. The second layer is applied by conventional atmospheric pressure plasma spraying. This facilitates the attachment of a durable thermally insulating ceramic coating directly to the surface of a highly oxidation resistant NiAl-based intermetallic alloy after the alloy has been preoxidized to promote the formation of a desirable Al2O3 scale.

  10. Formation of silicide based oxidation resistant coating over Mo-30 wt. % W alloy

    International Nuclear Information System (INIS)

    Silicide based oxidation resistant coatings were developed over Mo-30 W alloy using halide activated pack cementation process. Coated samples were characterized by SEM, optical microscopy, EDX and hardness measurements. Isothermal oxidation tests of coated alloy performed at 1000 deg C for 25h revealed a smaller weight gain at the initial stage of oxidation followed by no weight change indicating the protective nature of the coating. (author)

  11. Impact of dilution on the microstructure and properties of Ni-based 625 alloy coatings

    OpenAIRE

    Tiago Jose Antoszczyszyn; Rodrigo Metz Gabriel Paes; Ana Sofia Clímaco Monteiro de Oliveira; Adriano Scheid

    2014-01-01

    Nickel-based alloy IN 625 is used to protect components of aircrafts, power generation and oil refinery due to an association of toughness and high corrosion resistance. These properties are associated with the chemical composition and microstructure of coatings which depend on the processing parameters and the composition of the component being protected. This paper assessed impact of dilution on the microstructure and properties of the Ni alloy IN 625 deposited by Plasma Transferred Arc (PT...

  12. A first principles examination of phase stability in FCC-based Ni-V substitutional alloys

    International Nuclear Information System (INIS)

    In this paper the phase stability of fcc- based Ni-V substitutional alloys is investigated using linear muffin-tin orbitals total energy (LMTO) calculations. The method of Connolly and Williams (CWM) is used to extract many body interactions from the ground state energies of selected ordered configurations. These interactions are used in conjunction with the cluster variations method (CVM) to calculate the alloy phase diagram. The dependence of the interactions on the choice of configurations used to calculate them is examined

  13. Welding of cobalt-based amorphous alloys with Nd: YAG laser

    International Nuclear Information System (INIS)

    The paper describes the results concerning the investigation of the welding of cobalt-based amorphous alloys with Nd:YAG laser. Five alloys with different chemical structure and dimensions in shape of amorphous metal foils were welded. The quality of the welded joints were tested by using a microstructure analysis with an optical microscope and SEM, when the metal graphic structure, the chemical structure and the microhardness of the welded joints were tested as well. (Author)

  14. Control of equiaxed grains in a complicated Cu-Ni based alloy prepared by centrifugal casting

    OpenAIRE

    Luo Zongqiang; Zhang Weiwen; Xin Baoliang

    2011-01-01

    A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application. The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifugal casting. The results show that the equiaxed grains are determined by the pouring temperature of the melt, the cooling rate and the rotation speed of the mold. With the decrease in pouring temperature, the fraction of the equiaxed grains in the transverse section of the ingot i...

  15. Undercooling and demixing of copper-based alloys

    DEFF Research Database (Denmark)

    Kolbe, M.; Brillo, J.; Egry, I.; Herlach, D.M.; Ratke, L.; Chatain, D.; Tinet, N.; Antion, C.; Battezzati, L.; Curiotto, S.; Johnson, E.; Pryds, Nini

    Since the beginning of materials science research under microgravity conditions immiscible alloys have been an interesting subject. New possibilities to investigate such systems are offered by containerless processing techniques. Of particular interest is the ternary system Cu-Fe-Co, and its limi...

  16. SYNTHESIS AND PERFORMANCE OF FE-BASED AMORPHOUS ALLOYS FOR NUCLEAR WASTE REPOSITORY APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L; Perepezko, J; Hildal, K

    2007-02-08

    In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s that exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. Moreover, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinated computational analysis and experimental validation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys with increased cross-section for thermal neutron capture will be outlined to demonstrate that through careful design of alloy composition it is possible to tailor the material properties of the thermally spray-formed amorphous coating to accommodate the challenges anticipated in typical nuclear waste storage applications over tens of thousands of years in a variety of corrosive environments.

  17. Thermodynamic calculations in the development of high-temperature Co–Re-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gorr, Bronislava, E-mail: gorr@ifwt.mb.uni-siegen.de [University of Siegen, Institut für Werkstofftechnik, Siegen (Germany); Christ, Hans-Jürgen [University of Siegen, Institut für Werkstofftechnik, Siegen (Germany); Mukherji, Debashis; Rösler, Joachim [TU Braunschweig, Institut für Werkstoffe, Braunschweig (Germany)

    2014-01-05

    Highlights: • Phase diagram as a starting point for alloy development. • Design of pre-oxidation treatments by means of thermodynamic assessment. • Contribution of thermodynamic calculations to the general understanding of materials chemistry. -- Abstract: The experimental Co–Re-based alloys are being developed for high-temperature applications for service temperatures beyond 1100 °C. One of the main tasks of this research is to find the optimal chemical composition. Thermodynamic calculations are very helpful for composition selection and optimization. In this study, thermodynamic calculations were used to identify potential alloying elements and to determine suitable concentration ranges to improve properties, such as strength and oxidation resistance that are essential for high-temperature structural materials. The calculated ternary phase diagram of the Co–Re–Cr system was used to design the reference model alloy. Corrosion products formed under different atmospheric conditions were reliably predicted for a number of model Co–Re-based alloys. Pre-oxidation treatment, a common method used to improve the oxidation resistance of alloys in aggressive atmosphere, was successfully designed based on thermodynamic considerations.

  18. Improvement of Zr-base alloy for nuclear reactor core materials application by Mo addition

    International Nuclear Information System (INIS)

    The role of Mo in Zr-based alloys was studied in terms of the microstructure, texture and corrosion resistance. The base compositions of the experimental alloys were Zr-1Nb and Zr-1Nb-1Sn-0.1Fe to which Mo was added in varying amount up to 0.5%. Buttons of 300 g in weight have been produced by plasma arc remelting (PAR) and processed in sequence by hot forging, hot rolling, beta annealing, cold rolling and recrystallization annealing. It was confirmed that Mo addition resulted in grain refinement: beta grains as well as recrystallized alpha grains. This, in turn reduced the formation frequency and the size of twins and relaxed of the surface normal preferred orientation, fn. In the corrosion test in water containing 220 ppm LiOH (360 deg C, 17.9 MPa), the alloys with up to 0.2% Mo showed a good corrosion resistance whereas that with 0.5% Mo showed a degraded resistance. Apparently, the corrosion resistance was related to the density and morphology of the second phase particles. Alloys containing fine and uniformly distributed β-Nb particles showed good corrosion resistance whereas those containing excessive number or undesirable distribution of particles particularly in uncrystallized region showed degraded corrosion resistance. Overall, the present study suggests that alloying of up to 0.2% Mo should be favorably considered for improving the mechanical properties without impairing the corrosion resistance of Zr-based alloys for nuclear core applications. (author)

  19. Nickel-base alloy forgings for advanced high temperature power plants

    Energy Technology Data Exchange (ETDEWEB)

    Donth, B.; Diwo, A.; Blaes, N.; Bokelmann, D. [Saarschmiede GmbH Freiformschmiede, Voelklingen (Germany)

    2008-07-01

    The strong efforts to reduce the CO{sub 2} emissions lead to the demand for improved thermal efficiency of coal fired power plants. An increased thermal efficiency can be realised by higher steam temperatures and pressures in the boiler and the turbine. The European development aims for steam temperatures of 700 C which requires the development and use of new materials and also associated process technology for large components. Temperatures of 700 C and above are too high for the application of ferritic steels and therefore only Nickel-Base Alloys can fulfill the required material properties. In particular the Nickel-Base Alloy A617 is the most candidate alloy on which was focused the investigation and development in several German and European programs during the last 10 years. The goal is to verify and improve the attainable material properties and ultrasonic detectability of large Alloy 617 forgings for turbine rotors and boiler parts. For many years Saarschmiede has been manufacturing nickel and cobalt alloys and is participating the research programs by developing the manufacturing routes for large turbine rotor forgings up to a maximum diameter of 1000 mm as well as for forged tubes and valve parts for the boiler side. The experiences in manufacturing and testing of very large forgings made from nickel base alloys for 700 C steam power plants are reported. (orig.)

  20. Sheet texture modification in magnesium-based alloys by selective rare earth alloying

    International Nuclear Information System (INIS)

    Research highlights: → Different RE elements gave distinct microstructures and imparted different properties. → Gd demonstrated the highest potential to modify the sheet texture of rolled Mg. → Gd yielded excellent mechanical properties despite a coarse-grained microstructure. → RE alloying seems to promote the hard deformation mechanisms in Mg. → Indications of PSN were found in the annealed microstructures of rolled sheets. - Abstract: The current study examines the influence of select rare earth elements; Gd, Nd, Ce, La and mischmetal (MM) on the sheet texture modification during warm rolling and annealing of a ZEK100 magnesium alloy, and the resulting formability and anisotropy during subsequent tensile testing at room temperature. It was found that all the investigated RE elements led to weak sheet textures and hence promoted enhanced ductility and reduced anisotropy over conventional Mg sheet. Gd was of a particular interest because it gave rise to a desired Mg sheet texture despite its coarsest grain size resulting in promising mechanical properties. It is suggested that solute related effects on the grain boundary migration and the relative strengths of different deformation mechanisms are responsible for altering the common concepts of recrystallization and grain growth during annealing, and the activation scenarios of slip and twinning during deformation.

  1. Bond strength of resin cements to noble and base metal alloys with different surface treatments.

    Directory of Open Access Journals (Sweden)

    Farkhondeh Raeisosadat

    2014-10-01

    Full Text Available The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen.Cylinders of light cured Z 250 composite were cemented to "Degubond 4" (Au Pd and "Verabond" (Ni Cr alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05.When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021 and Verabond (P< 0.001. No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291 and Verabond (P=0.899. Panavia F2 showed a higher bond strength to sandblasted Verabond compared to RelyX Unicem (P=0.003. The bond strength of RelyX Unicem was significantly higher to Silano-Pen treated Verabond (P=0.011. The bond strength of the cements to sandblasted Degubond 4 showed no significant difference (P=0.59. RelyX Unicem had a higher bond strength to Silano-Pen treated Degubond 4 (P=0.035.The bond strength of resin cements to Verabond alloy was significantly higher than Degubond 4. RelyX Unicem had a higher bond strength to Silano-Pen treated alloys. Surface treatments of the alloys did not affect the bond strength of Panavia F2.

  2. Properties of thermally stable PM Al-Cr based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)], E-mail: Dalibor.Vojtech@vscht.cz; Verner, J. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Serak, J. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Simancik, F. [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3 (Slovakia); Balog, M. [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3 (Slovakia); Nagy, J. [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3 (Slovakia)

    2007-06-15

    The presented paper describes properties of Al-6.0 wt.%Cr-2.3 wt.%Fe-0.4 wt.%Ti-0.7 wt.%Si alloy produced by powder metallurgy (PM). The powder alloy was prepared by the pressure nitrogen melt atomization. The granulometric powder fraction of less than 45 {mu}m was then hot-extruded at 450 deg. C to produce a rod of 6 mm in diameter. Microstructure of the as-extruded material was composed of recrystallized {alpha}(Al) grains (the average grain size of 640 nm) and Al{sub 13}Cr{sub 2} spheroids (the average particle diameter of 130 nm and interparticle spacing of 290 nm). Metastable phases were not observed due to their decomposition on the hot extrusion. Hardness of the as-extruded material was 108 HV1, ultimate tensile strength, 327 MPa, yield strength, 258 MPa and elongation, 14%. Mechanical properties resulted mainly from Hall-Petch strengthening. The room-temperature mechanical properties were also measured after a long-term annealing at 400 deg. C. The investigated PM material was compared with the commercial Al-11.8 wt.%Si-0.9 wt.%Ni-1.2 wt.%Cu-1.2 wt.%Mg casting alloy generally applied at elevated temperatures. The PM alloy showed much higher thermal stability, since its room temperature hardness and tensile properties did not degradate significantly even after annealing at 400 deg. C/200 h. In contrast, the hardness and strength of the casting alloy reduced rapidly already after a 30 min annealing. The excellent thermal stability of the investigated PM material was a consequence of very slow diffusivities and low equilibrium solubilities of chromium and iron in solid aluminium.

  3. Properties of thermally stable PM Al-Cr based alloy

    International Nuclear Information System (INIS)

    The presented paper describes properties of Al-6.0 wt.%Cr-2.3 wt.%Fe-0.4 wt.%Ti-0.7 wt.%Si alloy produced by powder metallurgy (PM). The powder alloy was prepared by the pressure nitrogen melt atomization. The granulometric powder fraction of less than 45 μm was then hot-extruded at 450 deg. C to produce a rod of 6 mm in diameter. Microstructure of the as-extruded material was composed of recrystallized α(Al) grains (the average grain size of 640 nm) and Al13Cr2 spheroids (the average particle diameter of 130 nm and interparticle spacing of 290 nm). Metastable phases were not observed due to their decomposition on the hot extrusion. Hardness of the as-extruded material was 108 HV1, ultimate tensile strength, 327 MPa, yield strength, 258 MPa and elongation, 14%. Mechanical properties resulted mainly from Hall-Petch strengthening. The room-temperature mechanical properties were also measured after a long-term annealing at 400 deg. C. The investigated PM material was compared with the commercial Al-11.8 wt.%Si-0.9 wt.%Ni-1.2 wt.%Cu-1.2 wt.%Mg casting alloy generally applied at elevated temperatures. The PM alloy showed much higher thermal stability, since its room temperature hardness and tensile properties did not degradate significantly even after annealing at 400 deg. C/200 h. In contrast, the hardness and strength of the casting alloy reduced rapidly already after a 30 min annealing. The excellent thermal stability of the investigated PM material was a consequence of very slow diffusivities and low equilibrium solubilities of chromium and iron in solid aluminium

  4. A new double contrast barium enema

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Sang; Cho, Won Sik; Lee, Sung Woo; Lee, Mun Gyu; Jeon, Jeong Dong; Jaun, Woo Ki; Han, Chung Yul [Inje College Paik Hospital, Pusan (Korea, Republic of)

    1987-12-15

    A new technic of the barium enema was proposed for the better colonic double contrast study with the average 204ml of 50w/v% barium, applied to 109 serial patients. The barium was introduced to sigmoid colon, and then pushed to a mid transverse colon by the air insufflation through an enema syringe, a new device. An advance to cecum is accomplished by the air insufflation and/or the position change of the patient. The barium transfer method was developed for the best spot film exposure, through colon, by the position change of the patient, the tilting of the x-ray table and the air insufflation with the enema syringe. The mean angle of the x-ray table tilted was -10 .deg. at the beginning the barium enema till the barium sent past the splenic flexure, -15 . deg. for the best lateral view of rectum and -18 .deg. for the bet prone PA view of rectosigmoid colon. This was a simple, better and economic double contrast barium enema for the cooperative patients.

  5. Basic research for alloy design of Nb-base alloys as ultra high temperature structural materials; Chokoon kozoyo niobuki gokin no gokin sekkei no tame no kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E. [Tohoku University, Sendai (Japan); Yoshimi, K.; Hanada, S. [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1997-02-01

    This paper describes an influence of additional elements on the high temperature deformation behavior of Nb-base solid solution alloys. Highly concentrated solid solution single crystals of Nb-Ta and Nb-Mo alloys were prepared. Compression test and strain rate sudden change test were conducted in the vacuum at temperatures ranging from 77 to 1773 K, to determine the strain rate sensitivity index. Yield stress of the Nb-Ta alloy was similar to that of Nb alloy at temperatures over 0.3{times}T{sub M}, where T{sub M} is fusing point of Nb. While, the yield stress increased with increasing the impurity oxygen concentration at temperatures below 0.3{times}T{sub M}. The yield stress became much higher than that of Nb alloy. The strain rate sensitivity index showed positive values in the whole temperature range. On the other hand, the yield stress of Nb-Mo alloy was higher than that of Nb alloy in the whole temperature range, and increased with increasing the Mo concentration. The strain rate sensitivity index showed negative values at the temperature range from 0.3{times}T{sub M} to 0.4{times}T{sub M}. It was found that serration occurred often for Nb-40Mo alloys. 1 ref., 4 figs., 1 tab.

  6. Fracture mechanics data and modeling of environmental cracking of nickel-base alloys in high temperature water

    International Nuclear Information System (INIS)

    This paper reports on environmental cracking of ductile nickel-base alloys which has occurred both in pressurized water reactors and boiling water reactor components such as pressure-vessel safe ends, weld butters, and filler metals for joining nickel-base alloys or dissimilar metals, and attachment welding pads on pressure vessels. Accurate assessment of the interrelated effects of material, environment, and mechanics on environmental cracking behavior of ductile nickel-base alloys in 288C water

  7. Synthesis of barium titanium oxide from barium sulphate and anatase. Study of equimolar mixtures under different atmospheres

    International Nuclear Information System (INIS)

    To enable the ceramization of a barium sulphate-rich radioactive waste the synthesis of barium titanium oxide is studied by using anatase and barium sulphate. As a function of the calcination atmosphere, helium (or air) and Ar/H2, two reactions are studied. A mechanism of barium titanium oxide synthesis in helium (or in air) is proposed

  8. Improvement on Hot Workability of γ-TiAl Base Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    γ-TiAl base alloys have potential usage in aerospace engine fortheir high specific strength. In order to improve their poor hot workability, a new approach of hot deformation processing was investigated. The starting microstructure of Ti-46.5Al-2.5V-1.0Cr (atom percent, %) alloy is fully lamellar (FL) microstructure. The near gamma (NG) microstructure can be obtained through Nickel microalloying and heat treatment at 1 150 ℃. The isothermal compression tests were conducted on both materials using MTS machine at temperatures of 950 ℃, 1 000 ℃, and 1 050 ℃, and the strain rates of 0.01, 0.1 and 1 s-1. Compared with the γ-TiAl alloy with FL microstructure, the Ni-bearing alloy with NG microstructure has better hot workability, such as enlarged hot workable region, decreased flow stresses, more uniform and finer deformed microstructure.

  9. Effect of Sr on forming properties of Al-Mg-Si based alloy sheets

    Institute of Scientific and Technical Information of China (English)

    LU Guang-xi; CHEN Hai-jun; GUAN Shao-kang

    2006-01-01

    The effects of Sr element on the forming properties of the Al-Mg-Si based alloy sheets were studied by tensile test,metallograph, DSC, XRD, SEM and TEM. The results show that the tensile strength of aluminum alloy sheet added 0.033%(mass fraction)Sr increases comparing with that of free Sr. Simultaneously, the forming properties of sheets evidently increase, the elongation hardenability (n) and plastic strain ratio (r) and Erichsen number increase 27.8%, 11.1%, 10.8% and 12%, respectively,and the forming limit diagram increases evidently, too. The analysis shows that Sr is surface active element, which can refine grains of alloys, promote precipitation, reduce activation energy ofβ" phase, and lead the formation of α-(Al8Fe2Si) phase instead of β-(Al5FeSi) phase. As a result, the forming properties of the alloy sheet increase.

  10. Microstructure evolution model based on deformation mechanism of titanium alloy in hot forming

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-li; LI Miao-quan

    2005-01-01

    The microstructure evolution in hot forming will affect the mechanical properties of the formed product.However, the microstructure is sensitive to the process variables in deformation process of metals and alloys. A microstructure evolution model of a titanium alloy in hot forming, which included dislocation density rate and primary α phase grain size, was presented according to the deformation mechanism and driving forces, in which the effect of the dislocation density rate on the grain growth was studied firstly. Applying the model to the high temperature deformation process of a TC6 alloy with deformation temperature of 1 133 - 1 223 K, strain rate of 0.01 -50 s-1 and height reduction of 30%, 40% and 50%, the material constants in the present model were calculated by the genetic algorithm(GA) based objective optimization techniques. The calculated results of a TC6 alloy are in good agreement with the experimental ones.

  11. Effect of High Temperature Aging on the Corrosion Resistance of Iron Based Amorphous Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Day, S D; Haslam, J J; Farmer, J C; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys can be more resistant to corrosion than polycrystalline materials of similar compositions. However, when the amorphous alloys are exposed to high temperatures they may recrystallize (or devitrify) thus losing their resistance to corrosion. Four different types of amorphous alloys melt spun ribbon specimens were exposed to several temperatures for short periods of time. The resulting corrosion resistance was evaluated in seawater at 90 C and compared with the as-prepared ribbons. Results show that the amorphous alloys can be exposed to 600 C for 1-hr. without losing the corrosion resistance; however, when the ribbons were exposed at 800 C for 1-hr. their localized corrosion resistance decreased significantly.

  12. Thermal analysis of selected tin-based lead-free solder alloys

    DEFF Research Database (Denmark)

    Palcut, Marián; Sopoušek, J.; Trnková, L.; Hodúlová, E.; Szewczyková, B.; Ožvold, M.; Turňa, M.; Janovec, J.

    2009-01-01

    The Sn-Ag-Cu alloys have favourable solderability and wetting properties and are, therefore, being considered as potential lead-free solder materials. In the present study, tin-based Sn-Ag-Cu and Sn-Ag-Cu-Bi alloys were studied in detail by a differential scanning calorimetry (DSC) and...... thermodynamic calculations using the CALPHAD approach. The amount of the alloying elements in the materials was chosen to be close to the respective eutectic composition and the nominal compositions were the following: Sn-3.7Ag-0.7Cu, Sn-1.0Ag-0.5Cu-1Bi (in wt.%). Thermal effects during melting and solidifying...... simulated using the Thermo-Calc software package. This approach enabled us to obtain the enthalpy of cooling for each alloy and to compare its temperature derivative with the experimental DSC curves....

  13. Cobalt-based orthopaedic alloys: Relationship between forming route, microstructure and tribological performance

    International Nuclear Information System (INIS)

    The average longevity of hip replacement devices is approximately 10–15 years, which generally depends on many factors. But for younger generation patients this would mean that revisions may be required at some stage in order to maintain functional activity. Therefore, research is required to increase the longevity to around 25–30 years; a target that was initially set by John Charnley. The main issues related to metal-on-metal (MoM) hip replacement devices are the high wear rates when malpositioned and the release of metallic ions into the blood stream and surrounding tissues. Work is required to reduce the wear rates and limit the amount of metallic ions being leached out of the current MoM materials, to be able to produce an ideal hip replacement material. The most commonly used MoM material is the cobalt-based alloys, more specifically ASTM F75, due to their excellent wear and corrosion resistance. They are either fabricated using the cast or wrought method, however powder processing of these alloys has been shown to improve the properties. One powder processing technique used is spark plasma sintering, which utilises electric current Joule heating to produce high heating rates to sinter powders to form an alloy. Two conventionally manufactured alloys (ASTM F75 and ASTM F1537) and a spark plasma sintered (SPS) alloy were evaluated for their microstructure, hardness, tribological performance and the release of metallic content. The SPS alloy with oxides and not carbides in its microstructure had the higher hardness, which resulted in the lowest wear and friction coefficient, with lower amounts of chromium and molybdenum detected from the wear debris compared to the ASTM F75 and ASTM F1537. In addition the wear debris size and size distribution of the SPS alloy generated were considerably small, indicating a material that exhibits excellent performance and more favourable compared to the current conventional cobalt based alloys used in orthopaedics

  14. Cobalt-based orthopaedic alloys: Relationship between forming route, microstructure and tribological performance

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Bhairav [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Favaro, Gregory [CSM Instruments SA, Rue de la Gare 4, Galileo Center, CH-2034 Peseux (Switzerland); Inam, Fawad [Advanced Composite Training and Development Centre and School of Mechanical and Aeronautical Engineering, Glyndwr University, Mold Road, Wrexham LL11 2AW (United Kingdom); School of Engineering and Materials Science and Nanoforce Technology Ltd, Queen Mary University of London, London E1 4NS (United Kingdom); Reece, Michael J. [School of Engineering and Materials Science and Nanoforce Technology Ltd, Queen Mary University of London, London E1 4NS (United Kingdom); Angadji, Arash [Orthopaedic Research UK, Furlong House, 10a Chandos Street, London W1G 9DQ (United Kingdom); Bonfield, William [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Huang, Jie [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2012-07-01

    The average longevity of hip replacement devices is approximately 10-15 years, which generally depends on many factors. But for younger generation patients this would mean that revisions may be required at some stage in order to maintain functional activity. Therefore, research is required to increase the longevity to around 25-30 years; a target that was initially set by John Charnley. The main issues related to metal-on-metal (MoM) hip replacement devices are the high wear rates when malpositioned and the release of metallic ions into the blood stream and surrounding tissues. Work is required to reduce the wear rates and limit the amount of metallic ions being leached out of the current MoM materials, to be able to produce an ideal hip replacement material. The most commonly used MoM material is the cobalt-based alloys, more specifically ASTM F75, due to their excellent wear and corrosion resistance. They are either fabricated using the cast or wrought method, however powder processing of these alloys has been shown to improve the properties. One powder processing technique used is spark plasma sintering, which utilises electric current Joule heating to produce high heating rates to sinter powders to form an alloy. Two conventionally manufactured alloys (ASTM F75 and ASTM F1537) and a spark plasma sintered (SPS) alloy were evaluated for their microstructure, hardness, tribological performance and the release of metallic content. The SPS alloy with oxides and not carbides in its microstructure had the higher hardness, which resulted in the lowest wear and friction coefficient, with lower amounts of chromium and molybdenum detected from the wear debris compared to the ASTM F75 and ASTM F1537. In addition the wear debris size and size distribution of the SPS alloy generated were considerably small, indicating a material that exhibits excellent performance and more favourable compared to the current conventional cobalt based alloys used in orthopaedics. - Highlights

  15. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    In a prospective double blind study, acetylcysteine, a local and systemic respiratory tract mucolytic agent, or a placebo, were given to 100 patients prior to a double contrast barium meal to decrease the gastric mucus viscosity and to make the mucus layer thinner, in order to permit barium to outline the furrows surrounding the areae gastricae instead of the overlying thick mucus. However, acetylcysteine failed to improve either visualization of the areae gastricae or the general quality of the double contrast barium meal. (orig.)

  16. Potentiality of the “Gum Metal” titanium-based alloy for biomedical applications

    International Nuclear Information System (INIS)

    In this study, the “Gum Metal” titanium-based alloy (Ti–23Nb–0.7Ta–2Zr–1.2O) was synthesized by melting and then characterized in order to evaluate its potential for biomedical applications. Thus, the mechanical properties, the corrosion resistance in simulated body fluid and the in vitro cell response were investigated. It was shown that this alloy presents a very high strength, a low Young's modulus and a high recoverable strain by comparison with the titanium alloys currently used in medicine. On the other hand, all electrochemical and corrosion parameters exhibited more favorable values showing a nobler behavior and negligible toxicity in comparison with the commercially pure Ti taken as reference. Furthermore, the biocompatibility tests showed that this alloy induced an excellent response of MC3T3-E1 pre-osteoblasts in terms of attachment, spreading, viability, proliferation and differentiation. Consequently, the “Gum Metal” titanium-based alloy processes useful characteristics for the manufacturing of highly biocompatible medical devices. - Highlights: • The Gum Metal alloy composition was synthesized by melting in this study. • Appropriate mechanical properties for biomedical applications were obtained. • High corrosion resistance in simulated body fluids was observed. • Excellent in-vitro cell response was evidenced

  17. Potentiality of the “Gum Metal” titanium-based alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gordin, D.M. [Institut des Sciences Chimiques de Rennes (UMR CNRS 6226), INSA Rennes, 20 Avenue des Buttes de Coësmes, F-35043 Rennes Cedex (France); Ion, R. [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vasilescu, C.; Drob, S.I. [Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cimpean, A. [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Gloriant, T., E-mail: Thierry.Gloriant@insa-rennes.fr [Institut des Sciences Chimiques de Rennes (UMR CNRS 6226), INSA Rennes, 20 Avenue des Buttes de Coësmes, F-35043 Rennes Cedex (France)

    2014-11-01

    In this study, the “Gum Metal” titanium-based alloy (Ti–23Nb–0.7Ta–2Zr–1.2O) was synthesized by melting and then characterized in order to evaluate its potential for biomedical applications. Thus, the mechanical properties, the corrosion resistance in simulated body fluid and the in vitro cell response were investigated. It was shown that this alloy presents a very high strength, a low Young's modulus and a high recoverable strain by comparison with the titanium alloys currently used in medicine. On the other hand, all electrochemical and corrosion parameters exhibited more favorable values showing a nobler behavior and negligible toxicity in comparison with the commercially pure Ti taken as reference. Furthermore, the biocompatibility tests showed that this alloy induced an excellent response of MC3T3-E1 pre-osteoblasts in terms of attachment, spreading, viability, proliferation and differentiation. Consequently, the “Gum Metal” titanium-based alloy processes useful characteristics for the manufacturing of highly biocompatible medical devices. - Highlights: • The Gum Metal alloy composition was synthesized by melting in this study. • Appropriate mechanical properties for biomedical applications were obtained. • High corrosion resistance in simulated body fluids was observed. • Excellent in-vitro cell response was evidenced.

  18. Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

    International Nuclear Information System (INIS)

    Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na2SO4+H2SO4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

  19. Control of equiaxed grains in a complicated Cu-Ni based alloy prepared by centrifugal casting

    Directory of Open Access Journals (Sweden)

    Luo Zongqiang

    2011-02-01

    Full Text Available A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application. The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifugal casting. The results show that the equiaxed grains are determined by the pouring temperature of the melt, the cooling rate and the rotation speed of the mold. With the decrease in pouring temperature, the fraction of the equiaxed grains in the transverse section of the ingot increases and the average length of columnar grain decreases. When the pouring temperature is confined below 1,250℃, complete equiaxed grains can be obtained. Based on the optimal centrifugal casting processing, the tensile strength of the developed alloy ingot with complete equiaxed grains reaches to 810 MPa and 435 MPa at room temperature and 500℃, respectively, which is 14% and 110% higher than that of common commercial QAl10-4-4 alloy. The wear rate of the developed alloy is 7.0 × 10-8 and 3.8 × 10-7 mm3•N-1•mm-1 at room temperature and 500℃, respectively, which is 5 times and 39 times lower than that of QAl10-4-4 alloy.

  20. Pack cementation diffusion coatings for Fe-base and refractory alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1998-03-10

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels and refractory metal alloys. A new comprehensive theory to treat the multi-component thermodynamic equilibria in the gas phase for several coexisting solid phases was developed and used. Many different processes to deposit various types of coatings on several types of steels were developed: Cr-Si codeposition for low- or medium-carbon steels, Cr-Al codeposition on low-carbon steels to yield either a Kanthal-type composition (Fe-25Cr-4Al in wt.%) or else a (Fe, Cr){sub 3}Al surface composition. An Fe{sub 3}Al substrate was aluminized to achieve an FeAl surface composition, and boron was also added to ductilize the coating. The developmental Cr-lean ORNL alloys with exceptional creep resistance were Cr-Al coated to achieve excellent oxidation resistance. Alloy wires of Ni-base were aluminized to provide an average composition of Ni{sub 3}Al for use as welding rods. Several different refractory metal alloys based on Cr-Cr{sub 2}Nb have been silicided, also with germanium additions, to provide excellent oxidation resistance. A couple of developmental Cr-Zr alloys were similarly coated and tested.

  1. Description of the capacity degradation mechanism in LaNi{sub 5}-based alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Spodaryk, Mariana, E-mail: poshtamary@ukr.net [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Shcherbakova, Larisa; Sameljuk, Anatoly [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Wichser, Adrian; Zakaznova-Herzog, Valentina; Holzer, Marco; Braem, Beat [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Khyzhun, Oleg [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Mauron, Philippe; Remhof, Arndt [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Solonin, Yurii [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Züttel, Andreas [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Ecole polytechnique fédérale de Lausanne (EPFL), Institut des sciences et ingénierie chimiques, CH-1015 Lausanne (Switzerland)

    2015-02-05

    Highlights: • Morphology of gas atomised powders depends on the alloy composition. • Co substituted alloy electrodes exhibit slow activation and slow degradation. • The corrosion mechanism depends on the alloy composition and solubility of metals. - Abstract: The mechanism of the capacity degradation of LaNi{sub 5}-based alloy electrodes was investigated with a special focus on the influence of the alloy and surface composition, as well as the unique structure obtained by gas atomisation. The electrochemical properties, especially the cycle life curve (i.e. the capacity as a function of the cycle number of LaNi{sub 4.5}Al{sub 0.5}, LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1}, (La + Mm)Ni{sub 3.5}Co{sub 0.7}Al{sub 0.35}Mn{sub 0.4}Zr{sub 0.05}, and MmNi{sub 4.3}Al{sub 0.2}Mn{sub 0.5} alloy electrodes), was analysed and modelled. The capacity degradation upon cycling is determined by the chemical state of the alloy elements and the solubility of their oxides. The cycle life curves for the alloy electrodes without Co exhibited a rapid activation (3–4 cycles to reach maximum capacity), as well as rapid degradation (130–180 cycles for 50% maximum discharge capacity). LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1} and (La + Mm)Ni{sub 3.5}Co{sub 0.7}Al{sub 0.35}Mn{sub 0.4}Zr{sub 0.05} alloy electrodes activated after 7–10 cycles and showed very stable discharge behaviour (more than 400 cycles). The Co-containing alloy electrodes primarily lose the cycle stability because of mechanical decrepitation, whereas the alloys without Co suffer from selective dissolution of the unstable elements in the potential window, which was shown by our model of alloy degradation and confirmed by means of SEM, WDX, and ICP-OES data.

  2. Barium adsorption on the (110) and (111) molybdenum faces

    Energy Technology Data Exchange (ETDEWEB)

    Azizov, U.V.; Sabirov, S.T.; Dzhalilov, S.T. (Tashkentskij Gosudarstvennyj Univ. (USSR))

    1982-07-01

    Barium adsorption on Mo faces (110) and (111) was investigated by thermoemission and Cs surface ionization methods to obtain a more broad representation of barium adsorption at higher temperatures of cathode. Experiments show that the substrate temperature increase at a constant barium concentration results in the formation of small barium islands. At that, barium is under similar energy conditions in the small islands formed on the face (110) independent of relative areas of the islands.

  3. Atomic scale properties of magnetic Mn-based alloys probed by Emission Mössbauer spectroscopy

    CERN Multimedia

    Mn-based alloys are characterized by a wealth of properties, which are of interest both from fundamental physics point of view and particularly attractive for different applications in modern technology: from magnetic storage to sensing and spin-based electronics. The possibility to tune their magnetic properties through post-growth thermal processes and/or stoichiometry engineering is highly important in order to target different applications (i.e. Mn$_{x}$Ga) or to increase their Curie temperature above room temperature (i.e. off-stoichiometric MnSi). In this project, the Mössbauer effect will be applied at $^{57}$Fe sites following implantation of radioactive $^{57}$Mn, to probe the micro-structure and magnetism of Mn-based alloys at the most atomic-scale. The proposed experimental plan is devoted to establish a direct correlation between the local structure and bulk magnetism (and other physical properties) of Mn-based alloys.

  4. Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Min Zhu

    2013-10-01

    Full Text Available Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH2 are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys.

  5. The surface tension of liquid aluminium-based alloys

    International Nuclear Information System (INIS)

    In a systematic study, the surface tensions of the binary alloys Al-Fe and Al-Ni were investigated over a wide temperature and concentration range using electromagnetic levitation and the oscillating drop technique. Surface tensions were derived from the oscillation frequencies applying the formalism of Cummings and Blackburn. Temperature was measured by single-color pyrometry. Of particular interest in these alloys are melts corresponding to compositions of intermetallic phases, because potential ordering phenomena may influence all thermophysical properties. In both systems, an increase of the surface tension is observed at such concentrations. On the basis of partial excess Gibbs enthalpies, surface tensions can be calculated via the Butler equation and compared with experimental results. The agreement with our experimental data depends crucially on the quality of the thermodynamic potentials used. In addition, phenomenological models are also discussed, which describe the general trend correctly

  6. Dilatometer study of rapidly solidified aluminium-silicon based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Varga, B [University TRANSILVANIA, B-dul Eroilor nr. 29, 500036, Brasov (Romania); Fazakas, E; Hargitai, H [Inst. for Materials Science and Technology, Bay Z. Foundation, Fehervari ut, 130., H-1116 Budapest (Hungary); Varga, L K, E-mail: varga@szfki.h

    2009-01-01

    Aluminum-Silicon alloys are sought in a large number of automotive and aerospace applications due to their low coefficient of thermal expansion and high wear resistance. The present study focused on structural transformations as a function of the temperature of rapidly solidified hypereutectic Al{sub 100-x}Si{sub x} (x = 12, 22 and 40) alloys. Different structures out of equilibrium have been obtained after casting in sand, graphite and copper moulds and by melt spinning. The retained Si content in supersaturated alpha Al and the precipitation of Si is discussed in the light of the dilatometer studies [1, 2, 3] complemented by metallographic microscopy, XRD and DSC [4] measurements. A Kissinger analysis was used to determine the activation energy for the precipitation of supersaturated Si content.

  7. Fracture of niobium-base silicide coated alloy

    International Nuclear Information System (INIS)

    Mechanical properties and character of fracture of Nb-W-Mo-Zr-C alloy composition with complex by composition and structure silicide coating under different states of stage-by-stage coating are studied. Structural features, character of fracture from ductile to quasibrittle transcrystalline one and, respectively, the composition plasticity level are defined by interrelation of fracture processes in coating, matrix plastic flow and possibility and way of stress relaxation on their boundary

  8. Degradation mode survey of titanium-base alloys

    International Nuclear Information System (INIS)

    Of the materials reviewed, commercially pure titanium, Ti Gr 2, is the most susceptible to crevice corrosion. Ti Gr 7, 12, and 16 are likely to be resistant to crevice corrosion under the current expected Yucca Mountain repository conditions. Although Grade 7 has the greatest resistance to crevice corrosion it is also the most expensive. Although the possibility of sustained loads cracking exists, it has not yet been observed in a Ti alloys. For hydride precipitation to occur 100 degrees C, the hydrogen concentration would need to be relatively high, much higher than the maximum amount of hydrogen allowed during the manufacture of (α Ti alloys (0.0 15 wt%). A large amount of (SCC) stress corrosion cracking data accumulated at SNL and BNL for the WIPP program and by the Canadian Waste Management Program on titanium grades 2 and 12 indicates that there is no SCC at naturally occurring potentials in various brines. Hydride-induced cracking of titanium is a possibility and therefore, further investigation of this phenomenon under credible repository conditions is warranted. One disadvantage of titanium and its alloys is that their strengths decrease rather rapidly with temperature. This is due to the strong temperature dependence of interstitial solute strengthening mechanisms. Ti Gr 12 and 16 are recommended for further consideration as candidate materials for high level nuclear waste containers

  9. Development of rapidly solidified Al-Y-Ni-based alloys

    International Nuclear Information System (INIS)

    The present study is concerned with the effect of alloying additions (e.g. Co, Nb, Pd, La and Y) to the glass forming ability (GFA) of Al-Y-Ni alloys. Rapidly solidified ribbons of the following systems have been prepared by melt-spinning process: Al88Ni x/2Pd x/2Y12-x (x = 2, 5, 10), Al88Ni1Co1Y10-xLa x (x = 0, 5, 10), Al88Ni1Nb1Y10, and Al86Ni4-xCo xY10 (x = 1, 2, 3). Characterisation of the melt spun alloys was carried out through a combination of X-ray diffractometry, differential scanning calorimetry, and transmission electron microscopy. GFA in Al88Ni1TM1Y10 (where TM = Co, Nb, Pd) increases in the following order: Nb 88-Ni-Pd-Y systems the optimum quantity of yttrium is 10 at.%. A complete substitution of Y with La, or aluminium with 2 at.% of (Co,Ni) decreases the glass forming ability in Al88Ni1Co1Y10 but increases thermal stability of the residual amorphous phase. Partial replacement of Y with La significantly improves the thermal stability of the amorphous phase in Al-Ni-Co-Y

  10. Oxygen Behavior in Bulk Amorphous Zr-base Alloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Bulk Zr55Al10Ni5Cu30 metallic glass plates with a dimension of 85 mm×35mm×4 mm and a complicated plate werefabricated by injecting casting method using spongy zirconium and industrial purity aluminum, nickel and copper asraw materials. It was shown that the holding time of liquid metals at elevated temperatures had a great influence onthe oxygen content of the plates due to the contamination resulting from the atmosphere. Increasing holding timeresulted in the increase of oxygen content in the injected alloy. The glass transition temperatures of the bulk metallicglass plates are higher than that reported in the literature and crystallization temperature is lower for the one withhigher oxygen content at the same heating rate. The extension of the undercooled liquid region △Tx reaching about87 K is 3 K higher than that previously reported and 26 K higher than that with oxygen content of 0.076 wt pct forthe one with oxygen content as high as 0.065 wt pct. Therefore the oxygen content of the alloy has a significantinfluence on the glass forming ability and thermal stability of bulk metal glass. It is suggested that direct correlationbetween high glass forming ability and large △Tx is only valid for a well-defined Iow oxygen concentration or has tobe reconsidered by incorporating oxygen as an additional alloying element.

  11. Lead and barium sources in Cambrian siliciclastics and sediment provenance of a sector of the Taconic Orogen, Quebec: a mixing scenario based on Pb-isotopic evidence

    Science.gov (United States)

    Schrijver, K.; Zartman, R.E.; Williams-Jones, A. E.

    1994-01-01

    To test the hypothesis that siliciclastic rocks constituted the major source of Pb and Ba in barite-galena deposits of the Taconic Orogen, we determined Pb-isotope ratios in galena, barren rocks and contained minerals, as well as concentrations of Pb, U, Th and Ba in the latter (detrital feldspars, sandstones, mudstones, rock clasts and carbonate cements and clasts). Ranges in 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb of 28 galena samples are 17.96-18.05, 15.56-15.59 and 37.75-37.93, respectively; ranges for 41 barren rocks and minerals are 16.17-23.31, 15.26-15.86 and 35.98-42.51, respectively. The lowest ratios are in feldspar, and the highest in carbonate and mudstone. Values of the mudstones samples overlap those of galena when corrected for in situ decay of U and Th since galena precipitation (???450 Ma). We thus propose that mudstones constituted a source of lead. Corrected ratios for anomalously Pb-rich mudstones are virtually identical to galena-Pb ratios and may be due to contamination by lead-bearing brines. Assuming that burial diagenesis did not disturb the Pb-isotope values of sandstones, these rocks contributed only a minor fraction of lead to the galena, estimated at ???20% for one deposit. The source of barite-Ba was probably perthite. Low Ba and Pb concentrations of sandstone adjacent to this deposit, compared to high concentrations remote from it, support leaching of barium (and minor lead) from feldspar penecontemporaneous with feldspar dissolution. Geological data indicate that the provenance of the siliciclastic rocks was mainly from Grenville terrane. A comparison of our Pb-isotopic data for Taconic perthite with those of Grenville K-feldspar, as well as ratios of trace elements, support this provenance for both sandstones and mudstones. The presence of carbonate platforms peripheral to the orogen, and the Middle Ordovician-Middle Devonian depositional range of the studied and Mississippi Valley type deposits north (Newfoundland) and south (U

  12. Ageing dependence and martensite stabilization in copper based shape memory alloys

    International Nuclear Information System (INIS)

    Shape memory alloys exhibit a peculiar property called shape memory effect based on a first order solid state phase transformation, martensitic transformation which occurs in thermal manner on cooling the materials. Martensitic transformation is evaluated by the structural changes in microscopic scale. Copper-based ternary alloys exhibit shape memory effect in metastable beta phase region. These alloys have bcc-based ordered structures at high temperature, and transform martensiticaly to the long-period layered structures on cooling. The material atoms move cooperatively on (110)-type close packed planes of parent phase by means of a shear-like mechanism, and structural and fundamental properties of these alloys are altered by aging in the martensitic state. Therefore, the ageing gives rise to the structural changes in both long and short-range order in material. X-ray powder diffraction studies carried out in a long time interval on copper based shape memory alloys reveal that peak locations and intensities chance with ageing duration in martensitic condition, and these changes lead to the martensite stabilization in the redistribution or disordering manner, and stabilization proceeds by a diffusion-controlled process. (author)

  13. Ageing dependence and martensite stabilization in copper based shape memory alloys

    International Nuclear Information System (INIS)

    Shape memory alloys exhibit a peculiar property called shape memory effect based on a first order solid state phase transformation, martensitic transformation which occurs in thermal manner on cooling the materials. Martensitic transformation is evaluated by the structural changes in microscopic scale. Copper-based ternary alloys exhibit shape memory effect in metastable beta phase region. These alloys have bcc-based ordered structures at high temperature, and transform martensiticaly to the long-period layered structures on cooling. The material atoms move cooperatively on {110}-type close packed planes of parent phase by means of a shear-like mechanism, and structural and fundamental properties of these alloys are altered by aging in the martensitic state. Therefore, the ageing gives rise to the structural changes in both long and short-range order in material. X-ray powder diffraction studies carried out in a long time interval on copper based shape memory alloys reveal that peak locations and intensities chance with ageing duration in martensitic condition, and these changes lead to the martensite stabilization in the redistribution or disordering manner, and stabilization proceeds by a diffusion-controlled process

  14. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine

    Science.gov (United States)

    Graziana Genchi, Giada; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-01

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these ‘smart’ nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

  15. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine.

    Science.gov (United States)

    Genchi, Giada Graziana; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-10

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these 'smart' nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation. PMID:27145888

  16. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  17. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  18. Structure and mechanical properties of Ti-5Cr based alloy with Mo addition

    International Nuclear Information System (INIS)

    The effects of molybdenum (Mo) on the structure and mechanical properties of a Ti-5Cr-based alloy were studied with an emphasis on improving its strength/modulus ratio. Commercially pure titanium (c.p. Ti) was used as a control. As-cast Ti-5Cr and a series of Ti-5Cr-xMo (x = 1, 3, 5, 7, 9 and 11 wt.%) alloys were prepared by using a commercial arc-melting vacuum-pressure casting system, and investigated with X-ray diffraction (XRD) for phase analysis. Three-point bending tests were performed to evaluate the mechanical properties of all specimens and their fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that Ti-5Cr-7Mo, Ti-5Cr-9Mo and Ti-5Cr-11Mo alloys exhibited ductile properties, and the β-phase Ti-5Cr-9Mo alloy exhibited the lowest bending modulus. However, the Ti-5Cr-3Mo and Ti-5Cr-5Mo alloys had much higher bending moduli due to the formation of the ω phase during quenching. It is noteworthy that the Ti-5Cr-9Mo alloy exhibited the highest bending strength/modulus ratios at 26.0, which is significantly higher than those of c.p. Ti (8.5) and Ti-5Cr (13.3). Furthermore, the elastically recoverable angle of the Ti-5Cr-9Mo alloy (30o) was greater than that of c.p. Ti (2.7o). The reasonably high strength (or high strength/modulus ratio) β-phase Ti-5Cr-9Mo alloy exhibited a low modulus, ductile property, and excellent elastic recovery capability, which qualifies it as a novel implant materials.

  19. An Experimental Study on Rate-sensitive Tensile Deformation Behaviour of Fe-based Shape Memory Alloy

    OpenAIRE

    Iwamoto Takeshi; Fujita Kazuki

    2015-01-01

    Recently, it is attempted to apply high manganese steel including Fe-based shape memory alloy to vibration dampers. Especially, the alloy indicates a special characteristic as a well-known shape memory effect. By coupling between this effect and its plastic deformation, it can be considered that its deformation behaviour at higher deformation rate becomes quite complicated and still unclear. In this study, tensile tests of Fe-based shape memory alloy at different rate of deformation are condu...

  20. The mode of stress corrosion cracking in Ni-base alloys in high temperature water containing lead

    International Nuclear Information System (INIS)

    The mode of stress corrosion cracking (SCC) in Ni-base alloys in high temperature aqueous solutions containing lead was studied using C-rings and slow strain rate testing (SSRT). The lead concentration, pH and the heat treatment condition of the materials were varied. TEM work was carried out to observe the dislocation behavior in thermally treated (TT) and mill annealed (MA) materials. As a result of the C-ring test in 1M NaOH+5000 ppm lead solution, intergranular stress corrosion cracking (IGSCC) was found in Alloy 600MA, whereas transgranular stress corrosion cracking (TGSCC) was found in Alloy 600TT and Alloy 690TT. In most solutions used, the SCC resistance increased in the sequence Alloy 600MA, Alloy 600TT and Alloy 690TT. The number of cracks that was observed in alloy 690TT was less than in Alloy 600TT. However, the maximum crack length in Alloy 690TT was much longer than in Alloy 600TT. As a result of the SSRT, at a nominal strain rate of 1 x 10-7/s, it was found that 100 ppm lead accelerated the SCC in Alloy 600MA (0.01%C) in pH 10 at 340 C. IGSCC was found in a 100 ppm lead condition, and some TGSCC was detected on the fracture surface of Alloy 600MA cracked in the 10000 ppm lead solution. The mode of cracking for Alloy 600 and Alloy 690 changed from IGSCC to TGSCC with increasing grain boundary carbide content in the material and lead concentration in the solution. IGSCC seemed to be retarded by stress relaxation around the grain boundaries, and TGSCC in the TT materials seemed to be a result of the crack blunting at grain boundary carbides and the enhanced Ni dissolution with an increase of the lead concentration. (orig.)

  1. Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications

    International Nuclear Information System (INIS)

    Recent developments in multi-component Fe-based amorphous alloys have shown that these novel materials exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. During the past decade, amorphous alloy synthesis has advanced to allow for the casting of bulk metallic glasses. In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s. At such low cooling rates, there is an opportunity to produce amorphous solids through industrial processes such as thermal spray-formed coatings. Moreover, since cooling rates in typical thermal spray processing exceed 1000 K/s, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinated computational analysis and experimental validation. For example, a wedge casting technique has been applied to examine bulk glass forming alloys by combining multiple thermal probes with a measurement based kinetics analysis and a computational thermodynamics evaluation to elucidate the phase selection competition and critical cooling rate conditions. Based upon direct measurements and kinetics modeling it is evident that a critical cooling rate range should be considered to account for nucleation behavior and that the relative heat flow characteristics as well as nucleation kinetics are important in judging ease of glass formation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys

  2. Corrosion and mechanical property at high temperature of nickel based alloy for VHTR

    International Nuclear Information System (INIS)

    Using a very high temperature reactor (VHTR), it is conceptually and practically possible to generate highly efficient electricity and produce massive hydrogen among generation IV nuclear power plants. The structural material for an intermediate heat exchanger (IHX) is exposed to high temperature of up to 950 .deg. C. In this harsh environment, nickel-based alloys such as Alloy 617 and Haynes 230 are considered as promising candidate materials for IHX material owing to their excellent creep resistances at high temperature. However, high-temperature degradation cannot be avoided even for nickel-based alloy. Helium which inevitably includes impurities such as H2, CH4, H2O and CO is used as a coolant in a VHTR. Material degradation is aggravated by corrosion under an impure helium environment, which is one of the main obstacles to overcome for the application and successful long-term operation of a VHTR. A review of the thermodynamics indicates which reactions are available on the surface of the materials among oxidation, carburization and decarburization, but it does not give US the kinetic preference. This kinetic preference can induce localized corrosion, kinetic irreversibility and long-term material instability leading to material degradation. In addition to a long-term corrosion test under a VHTR coolant environment, the development of new alloys superior to commercial nickel-based alloy also give way to the successful establishment of a VHTR. Commercial nickel-based wrought alloy is strengthened by a solid solution and precipitation hardening mechanism in a wide temperature range of 500 to 900 .deg. C. The γ' significantly contributes to the strengthening by locking dislocation motion by an antiphase boundary at an intermediate temperature range of 700 to 800 .deg. C, but is no longer stable above this temperature range. However, the material for an IHX needs to fulfill the mechanical property requirements in a narrow and very high temperature range of 850 to

  3. Interface structure and formation mechanism of diffusion-bonded joints of TiAl-based alloy to titanium alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Vacuum diffusion bonding of a TiAl-based alloy (TAD) to a titanium alloy (TC2) was carried out at 1 273 K for 15~120 min under a pressure of 25 MPa. The kinds of the reaction products and the interface structures of the joints were investigated by SEM, EPMA and XRD. Based on this, a formation mechanism of the interface structure was elucidated. Experimental and analytical results show that two reaction layers have formed during the diffusion bonding of TAD to TC2. One is Al-rich α(Ti)layer adjacent to TC2,and the other is (Ti3Al+TiAl)layer adjacent to TAD,thus the interface structure of the TAD/TC2 joints is TAD/(Ti3Al+TiAl)/α(Ti)/TC2.This interface structure forms according to a three-stage mechanism,namely(a)the occurrence of a single-phase α(Ti)layer;(b)the occurrence of a duplex-phase(Ti3Al+TiAl)layer;and(c)the growth of the α(Ti)and (Ti3Al+TiAl)layers.

  4. Design and development of powder processed Fe-P based alloys

    International Nuclear Information System (INIS)

    Highlights: → The forming technique does not require any binder. Thus the system remains uncontaminated. → The use of ceramic protective coating eliminates the need of hydrogen protective atmosphere during heating. → Combined application of glassy ceramic coating and use of graphite as a reducing agent has lead to economy in P/M processing. → The technology developed in the present investigation showed very low coercivity and total loss values. -- Abstract: The present investigation deals with designing Fe, Fe-P binary and Fe-P-Si ternary alloys produced by an in-house developed powder metallurgical technique based on 'Hot Powder Preform Forging'. Proper soaking of preforms at high temperature (1050 oC) eliminates iron-phosphide eutectic and brings entire phosphorus into solution in iron. Attempting hot forging thereafter completely eliminates hot as well as cold shortness and thereby helps to form these preforms (alloys) into very thin sheets of 0.5 mm. The use of costly hydrogen atmosphere during sintering has been eliminated by the addition of carbon as a reducing agent to form CO gas within the compact by reacting with oxygen of iron powder particles. The glassy ceramic coating applied over the compact serves as a protective coating to avoid atmospheric oxygen attack over the compact held at high temperature. These alloys so formed were subjected to density examination at various stages. Microstructural study has been carried out to estimate the grain size, volume percentage of porosity in the alloys, and uniform distribution of phosphorus and silicon in an iron matrix. X-ray diffraction studies of these alloys revealed the presence of only ferrite as product phase. Addition of alloying elements such as P and Si has improved the resistivity and magnetic properties of iron. Fe-0.07C-0.2O-0.3P-0.5Si alloy showed a resistivity as high as 31.7 μΩ cm. Coercivity values of the alloys ranged from 0.51 to 1.98 Oe. The total magnetic loss of Fe-0.07C-0.2O-0.3P

  5. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  6. The size-effect on the formation enthalpy of nanosized binary ti based alloy

    International Nuclear Information System (INIS)

    The effects of grain size and composition on the formation enthalpy of nano binary Ti-based alloy are investigated by taking the surface effect into account within the modified Miedema model. It is demonstrated that the formation enthalpy of binary Ti based alloy with nano grains is size-dependent and exhibits evident size-effects. The formation enthalpy increases with the size decrease, and its value turns from negative to positive at a critical size, which will weaken the thermal stability of the nano grains. Furthermore, the composition segregation taking place in the nano grains of the Ti based alloy is obvious when the grain size is less than 10 nm and the tendency of segregation is dependent on the surface formation enthalpy of nanoparticle. (authors)

  7. An X-ray Fourier line shape analysis in cold-worked hexagonal titanium base alloys

    International Nuclear Information System (INIS)

    X-ray diffraction is an established technique for the analysis of microstructural parameters such as domain sizes, microstrains within the domains, and deformation fault densities in the deformed state of metals and alloys. These microstructural parameters influence the flow of dislocation in the lattice under deformation and thus regulate the strength and hardenability of the materials. The evaluation of such microdefects is this necessary for understanding the mechanical behavior of materials. In the present study, considering the wide applicability of titanium-base alloys in aviation industry, two alloy systems, i.e., titanium-base aluminum and titanium-base zirconium, have been selected. A number of X-ray diffraction profiles belonging to both fault-affected (H - K = 3N ± 1) and fault-unaffected (H - K = 3N) reflections have been recorded by a SIEMENS Kristolloflex-4 diffractometer using Cu Kα radiation, and the profiles have been analyzed to evaluate the microstructural parameters

  8. Vanadium alloys: development strategy

    International Nuclear Information System (INIS)

    A strategy for the development of vanadium alloys for use in radiation environments is outlined. An attractive reference alloy (V-15Cr-5Ti) has been identified. The critical issues in developing vanadium base alloys are summarized

  9. Rare earth-Mg-Ni-based hydrogen storage alloys as negative electrode materials for Ni/MH batteries

    International Nuclear Information System (INIS)

    Research highlights: → State-of-the-art of new R-Mg-Ni-based hydrogen storage electrode alloys is reviewed. → Electrode performances of the R-Mg-Ni-based alloys depend strongly on the stoichiometric ratio, alloy components and microstructure. → Optimized alloy compositions contain mainly metallic elements of La, Mg, Ni, Co, Mn and Al. → Pulverization of particles and oxidation/corrosion of active components are responsible for the fast capacity degradation. → Low-Co or Co-free R-Mg-Ni-based electrode alloys should be developed. - Abstract: This review is devoted to new rare earth-Mg-Ni-based (R-Mg-Ni-based) hydrogen storage alloys that have been developed over the last decade as the most promising next generation negative electrode materials for high energy and high power Ni/MH batteries. Preparation techniques, structural characteristics, gas-solid reactions and electrochemical performances of this system alloy are systematically summarized and discussed. The improvement in electrochemical properties and their degradation mechanisms are covered in detail. Optimized alloy compositions with high discharge capacities, good electrochemical kinetics and reasonable cycle lives are described as well. For their practical applications in Ni/MH batteries, however, it is essential to develop an industrial-scale homogeneous preparation technique, and a low-cost R-Mg-Ni-based electrode alloy (low-Co or Co-free) with high discharge capacity, long cycle life and good kinetics.

  10. Comparative evaluation of the effect of simulated porcelain firing cycle on the mechanical properties and microstructure of base metal ceramic alloys.

    OpenAIRE

    Singla A; Shetty P; Joseph M; Kotian R

    1999-01-01

    A comparison of mechanical properties and microstructure of four metal ceramic alloys in as-cast and heat-treated conditions resulted in significant differences. The alloys that were tested included two nickel-based and two cobalt-based metal ceramic alloys. Mechanical properties tested included strength, percent elongation and hardness. Ten tensile bars were cast for each alloy. Five of the ten bars for each alloy were randomly selected for heat treatment with the simulated porcelain firing ...

  11. Effects of can parameters on canned-forging process of TiAl base alloy(Ⅰ)--Microstructural analyses

    Institute of Scientific and Technical Information of China (English)

    刘咏; 韦伟峰; 黄伯云; 何双珍; 周科朝; 贺跃辉

    2002-01-01

    By using thermal simulation technique, the conventional canned-forging process of TiAl based alloy was studied. The effect of can parameters on the microstruct ures of TiAl alloy was analyzed in this process. The results show that, the defo rmation microstructure of TiAl based alloy without canning is inhomogeneous. In lateral area, crack and shearing lines can be found; while in central area, fine -grained shearing zone can be found. The effect of can is to reduce the seconda ry tensile stress. However, only when the deformation of the steel can is coinci dental with that of TiAl alloy ingot, can this effect be effective. Moreover, a thick can would enhance the microstructural homogeneity in TiAl based alloy. With the H/D ratio of the ingot increasing, the deformation of TiAl alloy would be more unsteady, therefore, a thicker can should be needed.

  12. Influence of Cumulative Plastic Deformation on Microstructure of the Fe-Al Intermetallic Phase Base Alloy

    Directory of Open Access Journals (Sweden)

    Bednarczyk I.

    2014-10-01

    Full Text Available This article is part of the research on the microstructural phenomena that take place during hot deformation of intermetallic phase-based alloy. The research aims at design an effective thermo - mechanical processing technology for the investigated intermetallic alloy. The iron aluminides FeAl have been among the most widely studied intermetallics because their low cost, low density, good wear resistance, easy of fabrication and resistance to oxidation and corrosion. There advantages create wide prospects for their industrial applications for components of machines working at a high temperature and in corrosive environment. The problem restricting their application is their low plasticity and their brittle cracking susceptibility, hampers their development as construction materials. Consequently, the research of intermetallic-phase-based alloys focuses on improvement their plasticity by hot working proceses. The study addresses the influence of deformation parameters on the structure of an Fe-38% at. Al alloy with Zr, B Mo and C microadditions, using multi – axis deformation simulator. The influence of deformation parameters on microstructure and substructure was determined. It was revealed that application of cumulative plastic deformation method causes intensive reduction of grain size in FeAl phase base alloy.

  13. Effects of AI Addition on the Thermoelectric Properties of Zn-Sb Based Alloys

    Institute of Scientific and Technical Information of China (English)

    CUI Jiaolin; LIU Xianglian; YANG Wei; CHEN Dongyong; MAO Liding; QIAN Xin

    2009-01-01

    The β-Zn4Sb3, emerged as a compelling p-type thermoelectric material, is widely used in heat-electricity conversion in the 400-650 K range. In order to probe the effects of slight doping on the crystal structure and physical properties, we prepared the samples of Al-added Zn-Sb based alloys by spark plasma sintering and evaluated their microstructures and thermoelectric properties. After a limited Al addition into the Zn-Sb based alloys we observed many phases in the alloys, which include a major phase β-Zn4Sb3,intermetallic phases ZnSb and AISb. The major β-Zn4Sb3 phase plays a fundamental role in controlling the thermoelectric performance, the precipitated phases ZnSb and AISb are of great importance to tailor the transport properties, such as the gradual enhancement of lattice thermal conductivity, in spite of an increased phonon scattering in additional grain boundaries. The highest thermoelectric figure of merit of 0.55 is obtained for the alloy with a limited AI addition at 653 K, which is 0.08 higher than that of un-doped β-Zn4Sb3 at the corresponding temperature. Physical property experiments indicate that there is a potentiality for the improvement of thermoelectric properties if a proper elemental doping is carried out into the Zn-Sb based alloys, which was confirmed by AI addition in the present work.

  14. Shear bond strength of a ceromer to noble and base metal alloys

    Directory of Open Access Journals (Sweden)

    Dorriz H.

    2006-08-01

    Full Text Available Background and Aim: The improvement of the physical and chemical properties of resins as well as great advances achieved in the field of chemical bonding of resin to metal has changed the trend of restorative treatments. Today the second generation of laboratory resins have an important role in the restoration of teeth. The clinical bond strength should be reliable in order to gain successful results. In this study the shear bond strength (SBS between targis (a ceromer and two alloys (noble and base metal was studied and the effect of thermocycling on the bond investigated. Materials and Methods: In this experimental study, alloys samples were prepared according to the manufacturer. After sandblasting of bonding surfaces with 50µ AI2o3 Targis was bonded to the alloy using Targis I link. All of the samples were placed in 37°C water for a period of 24 hours. Then half of the samples were subjected to 1000 cycles of thermocycling at temperatures of 5°C and 55°C. Planear shear test was used to test the bond strength in the Instron machine with the speed rate of 0.5mm/min. Data were analyzed by SPSS software. Two-way analysis of variance was used to compare the bond strength among the groups. T test was used to compare the alloys. The influence of thermocycling and alloy type on bond strength was studied using Mann Whitney test. P<0.05 was considered as the limit of significance. Result: The studied alloys did not differ significantly, when the samples were not thermocycled (P=0.136 but after thermocycling a significant difference was observed in SBS of resin to different alloys (P=000.1. Thermal stress and alloy type had significant interaction, with regard to shear bond strength (P=0.003. There was a significant difference in SBS before and after thermocycling in noble alloys (P=0.009, but this was not true in base metals (P=0.29. Maximum SBS (19.09 Mpa belonged to Degubond 4, before thermocycling. Minimum SBS (8.21 Mpa was seen in Degubond 4

  15. An experimental study on barium peritonitis in rats

    International Nuclear Information System (INIS)

    Barium sulfate is universally used contrast media in gastrointestinal roentgenology, and spillage of barium into peritoneal cavity can occur. The references on effect of barium sulfate in the peritoneal cavity have been scattered and the results are varied. In 80 rats, body weight of 130 gm to 150 gm, sterile pure barium, sterile commercial barium, intestinal content, and mixed pure barium and intestinal content were experimentally injected into the peritoneal cavity. Consecutive weekly laparotomy and microscopic examination were done for 4 weeks. The results are as followings: 1. Mind inflammatory reaction and mild adhesion after sterile pure barium injection. 2. Mild inflammatory reaction and moderate adhesion after sterile commercial barium injection. 3. Acute peritonitis and abscess formation after intestinal content injection. 4. High mortality due to severe acute peritonitis, and severe adhesion in survivors after injection of both pure barium and intestinal content.

  16. Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Luptáková Alena

    2015-12-01

    Full Text Available Acid mine drainage (AMD is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. The barium salts application presents one of the methods for the sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the sulphates precipitation in the form of barium sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by sulphate-reducing bacteria. Applied BaSO4 came from experiments of sulphates removal from Smolnik AMD using BaCl2.

  17. High Temperature Oxidation and Electrochemical Investigations on Ni-base Alloys

    OpenAIRE

    Obigodi-Ndjeng, Marthe Georgia

    2011-01-01

    This study examined high-temperature oxidation behavior of different Ni-base alloys. In addition, electrochemical characterization of the alloy’s corrosion behavior was carried out, including comparison of the properties of native passive films grown at room temperature and high temperature oxide scales. PWA 1483 (single-crystalline Ni-base superalloy) and model alloys Ni-Cr-X (where X is either Co or Al) were oxidized at 800 and 900 °C in air for different time periods. The superalloy showed...

  18. AFM research on the mechanism of Fe-based alloy stress annealed inducing magnetic anisotropy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cross-section of the Fe-based alloy (Fe73.5Cu1Nb3Si13.5B9) ribbon annealed at 540℃ under various tensile stress was investigated with atomic force microscope (AFM). The stress effect mechanism in Fe-based alloy ribbon tensile stress an-nealed inducing transverse magnetic anisotropy field was studied using the X-ray diffraction spectra and longitudinal drive giant magneto-impedance effect curves, and the model of direction dominant in encapsulated grain agglomeration was es-tablished. The relationship between the direction dominant in encapsulated grain agglomeration and magnetic anisotropy field was disclosed.

  19. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    International Nuclear Information System (INIS)

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  20. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  1. Formation and Oxidation Resistance of Silicide Coatings for Mo and Mo-Based Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The forming process of silicide coatings on pure Mo and Mo-base alloys, obtained by the gasphase deposition method, has been studied by examining the microstructure of coatings and the relationship between coating thickness and process parameters. It was shown that the growth of coatings was diffusion-controlled, the diffusion of silicon to be coated into Mo or Mo-base alloys was mainly responsible for the formation of silicide. The relationship between initial silicide thickness and oxidation resistance was also investigated, and the equation of service life of the coatings at high temperature in air is presented.

  2. Thermodynamic properties of lanthanum in gallium-indium eutectic based alloys

    OpenAIRE

    Shchetinskiy, A. V.; Dedyukhin, A. S.; Volkovich, V. A.; Yamshchikov, L. F.; Maisheva, A. I.; Osipenko, A. G.; Kormilitsyn, M. V.

    2013-01-01

    Activity and activity coefficients of lanthanum were determined for the first time in gallium-indium eutectic based alloys in a wide temperature range employing electromotive force method. Activity of β-La and super cooled liquid lanthanum in Ga-In eutectic based alloys between 573 and 1073 K linearly depends on the reciprocal temperature: lgaβ-La(Ga-In)=5.660-15, 352T±0.093 lgaLa(Ga-In)=6.074-15,839T±0.093 Activity coefficients of β-La and super cooled liquid lanthanum in this system at 617-...

  3. Novel Zn-based alloys for biodegradable stent applications: Design, development and in vitro degradation.

    Science.gov (United States)

    Mostaed, E; Sikora-Jasinska, M; Mostaed, A; Loffredo, S; Demir, A G; Previtali, B; Mantovani, D; Beanland, R; Vedani, M

    2016-07-01

    The search for a degradable metal simultaneously showing mechanical properties equal or higher to that of stainless steel and uniform degradation is still an open challenge. Several magnesium-based alloys have been studied, but their degradation rate has proved to be too fast and rarely homogeneous. Fe-based alloys show appropriate mechanical properties but very low degradation rate. In the present work, four novel Zn-Mg and two Zn-Al binary alloys were investigated as potential biodegradable materials for stent applications. The alloys were developed by casting process and homogenized at 350°C for 48h followed by hot extrusion at 250°C. Tube extrusion was performed at 300°C to produce tubes with outer/inner diameter of 4/1.5mm as precursors for biodegradable stents. Corrosion tests were performed using Hanks׳ modified solution. Extruded alloys exhibited slightly superior corrosion resistance and slower degradation rate than those of their cast counterparts, but all had corrosion rates roughly half that of a standard purity Mg control. Hot extrusion of Zn-Mg alloys shifted the corrosion regime from localized pitting to more uniform erosion, mainly due to the refinement of second phase particles. Zn-0.5Mg is the most promising material for stent applications with a good combination of strength, ductility, strain hardening exponent and an appropriate rate of loss of mechanical integrity during degradation. An EBSD analysis in the vicinity of the laser cut Zn-0.5Mg tube found no grain coarsening or texture modification confirming that, after laser cutting, the grain size and texture orientation of the final stent remains unchanged. This work shows the potential for Zn alloys to be considered for stent applications. PMID:27062241

  4. Preparation and characterization of aluminum based alloy - mica composites

    International Nuclear Information System (INIS)

    In this work, six pallets each of 2.0 cm dia and 0.5 cm thickness were prepared by powder metallurgy; half of them also contained 1% mica-powder to form a composite. Inclusion of mica resulted in a decreased density and an increased porosity of the sample. Brinell hardness was found to be 21% less for the composite than for the pure alloy. Micro-graphs of different areas of the sample show uniform distribution of mica particles and avoids around them. (author)

  5. Glass forming ability of iron based amorphous alloys depending on Mo, Cr and Co content

    International Nuclear Information System (INIS)

    The Fe41Co7Cr15Mo14C15B6Y2 multicomponent Fe-based alloy is known to be one of the best glass formers in iron-based systems and shows a critical casting thickness of 16 mm. The elements constituting the alloy have different influences on the glass forming ability. Therefore, the content of Mo, Cr and Co was systematically changed in the master alloy Fe77-x(Co,Cr,Mo)xC15B6Y2 to investigate how these three elements support the glassy microstructure. It was found that a certain content of Mo, Cr, and Co leads to a microstructure of amorphous matrix and α-Fe precipitates without any carbides.

  6. Crack growth rates for Ni--base alloys with the application to an operating BWR

    International Nuclear Information System (INIS)

    To perform adequate safety assessments of primary components in operating BWRs Crack Growth Rates (CGR) for Stress Corrosion Cracking in Normal Water Chemistry (NWC) as well as Hydrogen Water Chemistry (HWC) are needed. The data behind NUREG 0313 rev 2 was based on laboratory testing of sensitized stainless steels in oxygenated water. This so called NUREG-line overestimates CGRs for operating BWRs with respect to todays specification for water chemistry. In order to suggest new CGRs for Ni-base-alloys in the span from NWC to HWV we performed a literature review. Alloy 600 and welding alloys 182 and 82 were included in the search. The environments were NWC, 'partial' HWC and HWC

  7. Tensile properties of a nickel-base alloy subjected to surface severe plastic deformation

    International Nuclear Information System (INIS)

    A surface severe plastic deformation (S2PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S2PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening

  8. Cobalt base alloy surfacing. Influence of welding process on residual stress level

    International Nuclear Information System (INIS)

    Influence of welding conditions on alloy characteristics for wear resistant valves, cocks and fittings of nuclear power plants is studied. Three welding methods: oxyacetylene torch (OAT), plasma arc welding (PAW) and gas tungsten arc welding (TIG) are tested for welding hard cobalt base alloy (stellite 6) on two substrates (304 L and A 37). Parameters investigated are preheating temperature for PAW and TIG, dilution for PAW and flame type for OAT. Microstructure is dendritic with a solid solution Co Cr W and an interdentritic eutectic (the hard part). Hardness is more or less dilution dependent and slightly temperature dependent for preheating. Residual stress is measured by X-ray diffraction but application of this method is sometimes difficult because of grain size or cobalt base alloy texture

  9. Venous barium embolization, a rare, potentially fatal complication of barium enema: 2 case reports

    International Nuclear Information System (INIS)

    Venous embolization of barium has been recognized for 4 decades as one of the most dreaded complications of barium enema. Fortunately, the condition is extremely rare. In this report, the radiographic findings in 2 cases of venous embolization (one involving the portal vein and one systematic) are described, and ways to decrease the risk of this complication are discussed. (author)

  10. Role of hexadecapole interaction in proton rich barium isotopes

    International Nuclear Information System (INIS)

    From the systematic analysis of the experimental data on proton rich barium isotopes, it is observed that nuclei in the region z ≥ 50 and N≤82 are the transitional nuclei as they show a shape transition from spherical to deformed shape. An interesting feature of the observed yrast spectra in barium isotopic mass chain is the systematic variation of E2+, E4+ and E6+ excitation energy states from 120Ba to 136Ba. It is observed that these states follow a systematic decreasing trend as move away from 136Ba towards 120Ba. The isotopes 120-128Ba can be taken to be quasi-deformed nuclei having E4+/E2+ ratio larger than 2.7. Based on the systematics of low-lying states and the experimental data of quadrupole moments and B(E2) transition probabilities, the stable barium isotopes range from the approximately spherical 138Ba to l30Ba which is close to the deformed 120-128Ba isotopes. The purpose of the paper is to determine the importance of octupole-octupole and hexadecapole- hexadecapole parts of the two body interaction in reproducing the observed nuclear structure properties of 120-136Ba isotopes

  11. Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hattel, Jesper Henri; Hald, John

    2010-01-01

    Au–Sn based candidate alloys have been proposed as a substitute for high-lead content solders that are currently being used for high-temperature soldering. The changes in microstructure and microhardness associated with the alloying of Ag and Cu to the Au rich side as well to the Sn rich side of...... the Au–Sn binary system were explored in this work. Furthermore, the effects of thermal aging on the microstructure and microhardness of these promising Au–Sn based ternary alloys were investigated. For this purpose, the candidate alloys were aged at a lower temperature, 150°C for up to 1week and...

  12. Electron-phonon coupling in Ni-based binary alloys with application to displacement cascade modeling.

    Science.gov (United States)

    Samolyuk, G D; Béland, L K; Stocks, G M; Stoller, R E

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron-phonon (el-ph) coupling. The el-ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el-ph coupling. Thus, the el-ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10-20% in the alloys under consideration. PMID:27033732

  13. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    Science.gov (United States)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium–indium binary alloy (EGaIn) and gallium–indium–tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  14. Effect of boron addition on hydrogen embrittlement sensitivity in Fe-Ni based alloys

    International Nuclear Information System (INIS)

    In Fe-Ni based alloys, hydrogen embrittlement sensitivity is thought to correlate well with microstructure. The effect of boron addition on microstructure of Fe-Ni austenitic alloys has been investigated. It is found that 0.002 wt.% boron addition can significantly retard the formation of η phase, and only a few continuous carbides precipitate at the grain boundaries. As the boron content increases to 0.006 wt.%, carbides at grain boundaries become discontinuous, and are finer in size than that in the alloy with 0.002 wt.% boron. Significant decrease of the percent loss of reduction of area (RA) are seen in the alloys with boron contents lower than 0.006 wt.%. However, when further increasing the boron concentration to 0.01 wt.%, an increase in the percent loss of RA is found, due to the re-appearance of η phase and boride precipitation. Appropriate addition of boron can be an effective way of lowering hydrogen embrittlement sensitivity in Fe-Ni based alloys.

  15. Electron–phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    International Nuclear Information System (INIS)

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration. (paper)

  16. Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

    Energy Technology Data Exchange (ETDEWEB)

    Jolodosky, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fratoni, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-20

    Pre-conceptual fusion blanket designs require research and development to reflect important proposed changes in the design of essential systems, and the new challenges they impose on related fuel cycle systems. One attractive feature of using liquid lithium as the breeder and coolant is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. If the chemical reactivity of lithium could be overcome, the result would have a profound impact on fusion energy and associated safety basis. The overriding goal of this project is to develop a lithium-based alloy that maintains beneficial properties of lithium (e.g. high tritium breeding and solubility) while reducing overall flammability concerns. To minimize the number of alloy combinations that must be explored, only those alloys that meet certain nuclear performance metrics will be considered for subsequent thermodynamic study. The specific scope of this study is to evaluate the neutronics performance of lithium-based alloys in the blanket of an inertial confinement fusion (ICF) engine. The results of this study will inform the development of lithium alloys that would guarantee acceptable neutronics performance while mitigating the chemical reactivity issues of pure lithium.

  17. Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development

    Science.gov (United States)

    Sims, Zachary C.; Weiss, D.; McCall, S. K.; McGuire, M. A.; Ott, R. T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-07-01

    Several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  18. Electron–phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    Science.gov (United States)

    Samolyuk, G. D.; Béland, L. K.; Stocks, G. M.; Stoller, R. E.

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  19. Evaluation of Ni-Cr-base alloys for SOFC interconnect applications

    Science.gov (United States)

    Yang, Zhenguo; Xia, Guan-Guang; Stevenson, Jeffry W.

    To further understand the suitability of Ni-Cr-base alloys for solid oxide fuel cell (SOFC) interconnect applications, three commercial Ni-Cr-base alloys, Haynes 230, Hastelloy S and Haynes 242 were selected and evaluated for oxidation behavior under different exposure conditions, scale conductivity and thermal expansion. Haynes 230 and Hastelloy S, which have a relatively high Cr content, formed a thin scale mainly comprised of Cr 2O 3 and (Mn,Cr,Ni) 3O 4 spinels under SOFC operating conditions, demonstrating excellent oxidation resistance and a high scale electrical conductivity. In contrast, a thick double-layer scale with a NiO outer layer above a chromia-rich substrate was grown on Haynes 242 in moist air or at the air side of dual exposure samples, indicating limited oxidation resistance for the interconnect application. With a face-centered-cubic (FCC) substrate, all three alloys possess a coefficient of thermal expansion (CTE) that is higher than that of candidate ferritic stainless steels, e.g. Crofer22 APU. Among the three alloys, Haynes 242, which is heavily alloyed with W and Mo and contains a low Cr content, demonstrated the lowest average CTE at 13.1 × 10 -6 K -1 from room temperature to 800 °C, but it was also observed that the CTE behavior of Haynes 242 was very non-linear.

  20. Gilbert damping and anisotropic magnetoresistance in iron-based alloys

    Science.gov (United States)

    Berger, L.

    2016-07-01

    We use the two-current model of Campbell and Fert to understand the compositional dependence of the Gilbert damping parameter in certain iron alloys. In that model, spin-up and spin-down carriers have different resistivities ρ↑ and ρ↓. We emphasize the part of the Gilbert parameter, called Gsf, generated by spin-flip interband processes. Both Gsf and the anisotropic magnetoresistance Δρ are proportional to the square of the spin-orbit parameter, and also proportional to ρ↑. In bcc alloys of iron with V, Cr, Mo, etc. solutes on the left of iron in the periodic table, ρ↑ is increased by a scattering resonance (Gomes and Campbell, 1966, 1968). Then ρ↑, Δρ, and Gsf all exhibit a peak at the same moderate concentration of the solute. We find the best fit between this theory and existing experimental data of Gilbert damping for Fe-V epitaxial films at room temperature (Cheng, 2006; Scheck et al., 2007). At room temperature, the predicted Gsf peak is masked by a background arising from non-flip intraband processes. At elevated temperatures, the peak is expected to become more prominent, and less hidden in the background.

  1. Creep rupture testing of alloy 617 and A508/533 base metals and weldments.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Soppet, W.K.; Rink, D.L. (Nuclear Engineering Division)

    2012-01-17

    The NGNP, which is an advanced HTGR concept with emphasis on both electricity and hydrogen production, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 750-1000 C. Alloy 617 is a prime candidate for VHTR structural components such as reactor internals, piping, and heat exchangers in view of its resistance to oxidation and elevated temperature strength. However, lack of adequate data on the performance of the alloy in welded condition prompted to initiate a creep test program at Argonne National Laboratory. In addition, Testing has been initiated to evaluate the creep rupture properties of the pressure vessel steel A508/533 in air and in helium environments. The program, which began in December 2009, was certified for quality assurance NQA-1 requirements during January and February 2010. Specimens were designed and fabricated during March and the tests were initiated in April 2010. During the past year, several creep tests were conducted in air on Alloy 617 base metal and weldment specimens at temperatures of 750, 850, and 950 C. Idaho National Laboratory, using gas tungsten arc welding method with Alloy 617 weld wire, fabricated the weldment specimens. Eight tests were conducted on Alloy 617 base metal specimens and nine were on Alloy 617 weldments. The creep rupture times for the base alloy and weldment tests were up to {approx}3900 and {approx}4500 h, respectively. The results showed that the creep rupture lives of weld specimens are much longer than those for the base alloy, when tested under identical test conditions. The test results also showed that the creep strain at fracture is in the range of 7-18% for weldment samples and were much lower than those for the base alloy, under similar test conditions. In general, the weldment specimens showed more of a flat or constant creep rate region than the base metal specimens. The base alloy and the weldment exhibited tertiary creep

  2. Nickel based alloys compatibility with fuel salts for molten salt reactor with thorium and uranium support

    International Nuclear Information System (INIS)

    R and D on molten salt reactors (MSR) in Europe are concentrated now on fast/intermediate spectrum concepts which were recognised as long-term alternative to solid fuelled fast reactors due to their attractive features: strong negative feedback coefficients, easy in-service inspection, and simplified fuel cycle. For high-temperature MSR corrosion of the metallic container alloy in primary circuit is the primary concern. Key problem receiving current attention include surface fissures in Ni-based alloys probably arising from fission product tellurium attack. This paper summarises results of corrosion tests conducted recently to study effect of oxidation state in selected fuel salts on tellurium attack and to develop means of controlling tellurium cracking in the special Ni - based alloys recently developed for large power units: molten salt actinide recycler and transmuter (MOSART) and molten salt fast reactor (MSFR). Tellurium corrosion of Ni-based alloys was tested in the temperature range from 730 deg. C up to 800 deg. C in stressed and unloaded conditions with fuel LiF-BeF2-UF4 and LiF-BeF2-ThF4-UF4 salt mixtures at different [U(IV)]/[U(III)] ratios from 0.7 up to 500. Following Russian and French Ni-based alloys (in mass%): HN80M-VI (Mo-12, Cr-7.6, Nb-1.5), HN80MTY (Mo-13, Cr-6.8, Al-1.1, Ti-0.9), HN80MTW (Mo-9.4, Cr-7.0, Ti-1.7, W-5.5) and EM-721 (W-25.2, Cr-5.7, Ti-0.17) were used for the study in the corrosion facility. The HN80MTY alloy has shown the best resistance against Te cracking and after test mechanical properties. (authors)

  3. Synthesis of barium mercaptides and application of antimony/barium mercaptides

    Institute of Scientific and Technical Information of China (English)

    瞿龙; 张露露; 舒万艮

    2001-01-01

    Mercaptoacetic acid, isooctyl thioglycolate and barium hydroxide used as start materials, barium bis (2-ethylhexyl thioglycolate) (Ba(2EHTG)2), barium thioglycolate (Ba(TG)) and barium bisthioglycolate (Ba(TG)2) were synthesized. Their optimum synthetic techniques were discussed, and some physicochemical data were reported. Infrared spectroscopy and elemental analysis methods were used to identify the structures. They were put into PVC plastic products together with antimony tris (2-ethylhexyl thioglycolate) (Sb(2EHTG)3) under the suitable compounding, and their heat stability to PVC was studied. It is shown that these barium mercaptides have remarkable synergisms with antimony mercaptides and the long-term stabilizing effect of organoantimony stabilizer can be effectively improved, reducing the amount of antimony compounds so as to avoid the decrease of its stabilizing effect.

  4. Quaternary alloys based on II-VI semiconductors

    CERN Document Server

    Tomashyk, Vasyl

    2014-01-01

    Systems Based on ZnSSystems Based on ZnSeSystems Based on ZnTeSystems Based on CdSSystems Based on CdSeSystems Based on CdTeSystems Based on HgSSystems Based on HgSeSystems Based on HgTeIndexReferences appear at the end of each chapter.

  5. Ternary alloys based on II-VI semiconductor compounds

    CERN Document Server

    Tomashyk, Vasyl; Shcherbak, Larysa

    2013-01-01

    Phase Equilibria in the Systems Based on ZnSSystems Based on ZnSeSystems Based on ZnTeSystems Based on CdSSystem Based on CdSeSystem Based on CdTeSystems Based on HgSSystems Based on HgSeSystems Based on HgTeIndexReferences appear at the end of each chapter.

  6. The influence of thermomechanical treatment on structure of FeAl intermetallic phase-based alloys

    Directory of Open Access Journals (Sweden)

    I. Bednarczyk

    2008-08-01

    Full Text Available Purpose: The major problem restricting universal employment of intermetallic phase base alloy is their low plasticity which leads to hampering their development as construction materials. The following work concentrates on the analysis of microstructure and plasticity of ordered FeAl (B2 alloy during cold and hot deformation and rolling process.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 800, 900 and 1000°C at 0.1s-1 strain rate. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. The process was conducted on the K -350 quarto rolling mill used for hot rolling of flat products. The process was conducted in some stages at temperature ranging from 1200-1000°C: Structural examination was carried out using light microscopy. The examination of the substructure was carried out by transmission electron microscopy (TEM.Findings: The research carried out enabled the understanding of the phenomena taking place during hot rolling of the investigated alloy. which has been also confirmed in plastometric studies conducted in the form of hot compression tests. The microstructure analyses applying optic and electron microscopy have revealed the structure reconstruction processes occurring in FeAl alloys during cold and hot deformation.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated alloy. The obtained sheets can be used as constructional elements working in complex stress fields, at a high temperature and corrosive environments. The results will constitute the basis for modelling the structural changes.Originality/value: The obtained results are vital for designing an effective thermo - mechanical processing technology for the

  7. Magnetic properties of two new uranium-based alloys: UAuCu4 and UPdCu4

    International Nuclear Information System (INIS)

    Two new uranium-based alloys UAuCu4 and UPdCu4 have been prepared and their magnetic properties studied. The NMR of the isotope 63Cu in these alloys suggests that they are well ordered ternary materials. There is a strong correlation between the occupancy of the (4c) sites in the structure and the relative size of the two non-uranium atoms in these alloys. (author)

  8. Hydrogen-plasticity interactions in nickel and nickel base alloys

    International Nuclear Information System (INIS)

    We evaluate the different contributions of the hydrogen-dislocation interactions to the plasticity of fcc materials in order to feed predictive models of stress corrosion cracking. Static strain ageing experiments are used to quantify the hardening contribution of solute drag by dislocations to the flow stress. We demonstrate the role of hydrogen transport by dislocations on the fracture mechanism. We model the influence of the screening of the elastic field of dislocations by hydrogen on elementary plasticity mechanisms and we conclude that the decrease of the cross slip ability arises from the combined action of elastic and core effects. The testing of single crystals shows that the major effect is on the cross slip mechanism. Tensile tests on polycrystals enlighten the diversity of macroscopic responses observed in alloys. (author)

  9. Superconducting state parameters of indium-based binary alloys

    Indian Academy of Sciences (India)

    A M Vora; Minal H Patel; P N Gajjar; A R Jani

    2002-05-01

    Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz; electron–phonon coupling strength , Coulomb pseudopotentialµ *, transition temperature c, isotope effective exponent and interaction strength 0 for the In1-Zn and In1-Sn binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor, Vashistha–Singwi, Ichimaru–Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging, which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture.

  10. Characterization of hydrogen barrier coatings for titanium-base alloys

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the barrier efficiency of a thick thermal spray deposit on the α-titanium alloy, Ti-5Al-2.4Sn against hydrogen penetration. Therefore, a duplex coating has been applied by plasma spraying using a Sulzer Metco F4 gun. The selected duplex coating system consisted of a 0.1-0.2 mm thick tantalum bond layer and a chromium oxide top layer doped with 3 wt% titanium oxide. The achieved thickness of the top layer was about 0.6 mm. The coated specimens have been characterized with regard to bond strength, hardness and microstructure. Hydrogen charging experiments were performed in a Sievert's apparatus

  11. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  12. Strengthening of Mg based alloy through grain refinement for orthopaedic application.

    Science.gov (United States)

    Nayak, Soumyaranjan; Bhushan, Bharat; Jayaganthan, R; Gopinath, P; Agarwal, R D; Lahiri, Debrupa

    2016-06-01

    Magnesium is presently attracting a lot of interest as a replacement to clinically used orthopaedic implant materials, due to its ability to solve the stress shielding problems, biodegradability and osteocompatibility. However, the strength of Mg is still lower than the requirement and it becomes worse after it starts degrading fast, while being exposed in living body environment. This research explores the effectiveness of 'grain refinement through deformation', as a tool to modify the strength (while keeping elastic modulus unaffected) of Mg based alloys in orthopaedic application. Hot rolled Mg-3wt% Zn alloy (MZ3) has been investigated for its potential in orthopaedic implant. Microstructure, mechanical properties, bio-corrosion properties and biocompatibility of the rolled samples are probed into. Grain size gets refined significantly with increasing amount of deformation. The alloy experiences a marked improvement in hardness, yield strength, ultimate tensile strength, strain and toughness with finer grain size. An increment in accelerated corrosion rate is noted with decreasing grain size, which is correlated to the increased grain boundary area and mechano-chemical dissolution. However, immersion test in simulated body fluid (SBF) reveals reduction in corrosion rate after third day of immersion. This was possible owing to precipitation of protective hydroxyapatite (HA) layer, formed out of the interaction of SBF and the alloy. More nucleation sites at the grain boundary for fine grained samples help in forming more HA and thus reduce the corrosion rate. Human osteosarcoma cells show less viability and adhesion on grain refined alloy. PMID:26745721

  13. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  14. New high strength technologically ecological and expedient economically advantageous alloys on Fe-C base

    International Nuclear Information System (INIS)

    The paper presents framework a part of by now obtained results of the authors studies in the period 1967(68) - 2002 about possibilities for obtaining new high-strength and wear resistant cast alloys on, Fe-C base (complex alloyed steels and cast irons of different systems with different structure, reflected in over 125 articles, 15 inventions (patents) and other scientific studies. The paper includes summarized results and discussion. Key words: new austenite steels and cast irons, mechanical characteristics, wear resistance. (Original)

  15. An X-ray diffraction study of defect parameters in a Ti-base alloy

    Indian Academy of Sciences (India)

    G Karmaker; P Mukherjee; A K Meikap; S K Chattopadhyay; S K Chatterjee

    2001-12-01

    Detailed studies based on the well established method of Fourier line shape analysis have been made on the X-ray diffraction profile of hexagonal titanium alloy of nominal composition Ti–6.58% Al–3.16% Mo–1.81% Zr–0.08% Fe–0.012% N–0.0078% C. While deformation fault probability, , has been found to be quite high compared to that of pure titanium, the deformation growth fault parameter, , shows a negative value ruling out the presence of growth fault in this alloy in the deformed state.

  16. Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment

    International Nuclear Information System (INIS)

    Results of low cycle fatigue tests on alloy Mar-M-246 and Inconel 713 are presented. Based on the limited data, it was concluded that the Mar-M-246 material had a cyclic life in hydrogen that averaged three times higher than the alloy 713LC material for similar strain ranges. The hydrogen environment reduced life for both materials. The life reduction was more than an order of magnitude for the 713LC material. Porosity content of the cast specimens was as expected and was an important factor governing low cycle fatigue life

  17. Chemical durability and degradation mechanisms of HT9 based alloy waste forms with variable Zr content

    Energy Technology Data Exchange (ETDEWEB)

    Olson, L. N. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-30

    In Corrosion studies were undertaken on alloy waste forms that can result from advanced electrometallurgical processing techniques to better classify their durability and degradation mechanisms. The waste forms were based on the RAW3-(URe) composition, consisting primarily of HT9 steel and other elemental additions to simulate nuclear fuel reprocessing byproducts. The solution conditions of the corrosion studies were taken from an electrochemical testing protocol, and meant to simulate conditions in a repository. The alloys durability was examined in alkaline and acidic brines.

  18. Effect of TBC on oxidation behaviour of γ-TiAl based alloy

    OpenAIRE

    G. Moskal

    2007-01-01

    Purpose: The purpose of the research was identification of the influence of TBC coating system on oxidation resistance of TiAl based alloy during oxidation at temperature of 900°C and 950°C for 500h and 200h respectively.Design/methodology/approach: The APS technique was used to modify and improvement of oxidation resistance of TiAl intermetallic alloy. As a bond coat the NiCrAlY overlay coating was applied. The bond-coat provided a good bonding strength between matrix and ceramic top coat. T...

  19. Effect of cold work on initiation stage crack growth rate of nickel based alloys

    International Nuclear Information System (INIS)

    To investigate the effect of cold work on initiation stage crack growth rates of nickel based alloy, initiation stage crack growth rates were measured for simulated PWR primary water conditions using flat type specimens which were prepared from three different heats of alloy 600 and then 20 and 40% cold worked. Almost all data showed the stress had an increasing linear dependency on crack growth rate ; however there was some scattering of data and some materials showed a different tendency. Since yield strength was increased by cold work, for the same stress, the initiation stage crack growth rates were restrained or were not changed significantly by cold work. (author)

  20. Integrated Design and Rapid Development of Refractory Metal Based Alloys for Fossil Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, O.N.; King, P.E.; Gao, M.C.

    2008-07-01

    One common barrier in the development of new technologies for future energy generating systems is insufficiency of existing materials at high temperatures (>1150oC) and aggressive atmospheres (e.g., steam, oxygen, CO2). To overcome this barrier, integrated design methodology will be applied to the development of refractory metal based alloys. The integrated design utilizes the multi-scale computational methods to design materials for requirements of processing and performance. This report summarizes the integrated design approach to the alloy development and project accomplishments in FY 2008.

  1. Electronic aspects of the martensitic transition in Ni-Mn based Heusler alloys

    International Nuclear Information System (INIS)

    The martensitic transformation temperature Ms depends linearly on the valence electron concentration for Ni-Mn-X Heusler systems where X is a group III-group V element. However, the slopes of the linearity are different for alloys with different X species and increases either as X changes from Al to In (isoelectronic) or from In to Sb (increase in number of p electrons). We discuss the features in the Ms vs e/a diagram and the relative stability of the various crystallographic phases of Ni-Mn based Heusler alloys

  2. Structural and mechanical characteristics of some lead-free Cu-Sn based solder alloys

    OpenAIRE

    Mitovski Aleksandra M.; Balanović Ljubiša T.; Živković Dragana T.; Marjanović Šaša R.; Marjanović Bata R.; Novaković Slađana O.

    2008-01-01

    The results of structural and mechanical characteristics of lead-free Cu-Sn based solder alloys, produced in Company "11. mart" AD Srebrenica (Republic of Srpska), are presented in this paper. The results of investigation of samples - alloys CuSnl4, CuSnlFelAlO.5, CuSnlOFelAllMnO.5 and CuA110Fe3Mn produced by different processing methods, include the data obtained by optical microscopy and measurements of hardness, micro hardness and electroconductivity, in order to characterize mentioned all...

  3. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    Science.gov (United States)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  4. Electrochemical machining of hard tungsten carbide base alloys in neutral solutions using anodal pulses imposition

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, A.D.; Klepikov, R.P.; Moroz, I.I.

    1981-01-01

    The experiments carried out show that activating pulses of higher amplitude imposition on constant comparatively low voltage extends the possibility of anodic dissolution process control. It proves to be possible to select pulse and constant voltage parameters, allowing to decrease the passivation effect and conduct the process of electrochemical machining of hard tungsten carbide base alloys in neutral water solutions.

  5. Electrochemical machining of hard tungsten carbide base alloys in neutral solutions using anodal pulses imposition

    International Nuclear Information System (INIS)

    The experiments carried out show that activating pulses of higher amplitude imposition on constant comparatively low voltage extends the possibility of anodic dissolution process control. It proves to be possible to select pulse and constant voltage parameters, allowing to decrease the passivation effect and conduct the process of electrochemical machining of hard tungsten carbide base alloys in neutral water solutions

  6. Property enhancement of orthorhombic Ti2AlNb-based intermetallic alloys

    International Nuclear Information System (INIS)

    This paper provides an overview of our research efforts aimed at improving the room and high temperature mechanical properties of an orthorhombic Ti2AlNb-based Ti-22Al-27Nb intermetallic alloy by the microstructural and compositional modifications, and the dispersion of fine TiB particulates. Challenges in each of the activities is highlighted and discussed. (orig.)

  7. Heterogeneous Nb-Based Nuclei for the Grain Refinement of Al-Si Alloys

    Science.gov (United States)

    Bolzoni, L.; Hari Babu, N.

    2016-05-01

    Nb-based intermetallics are, generally, low-density high-temperature materials used for structural applications or cryogenic superconductors. In this work, we report the development of an Al(96)-Nb(2)-B(2) master alloy where in situ-formed micrometric Nb-based intermetallics (i.e. NbB2 and Al3Nb) are used for a completely different purpose: to promote the refinement of Al-Si alloys by taking advantage of enhanced heterogeneous nucleation. Nb-based intermetallics have the right characteristics, like low density, stability at high temperature and good lattice match, to be used as heterogeneous nucleation substrates. It was found that the addition of these Nb-based intermetallics permits the significant refinement of the microstructural features of the Al-Si alloy studied. The enhanced heterogeneous nucleation makes the grain size of the material far less dependent on the cooling rate, which is one of the critical parameters influencing the variation of the properties of the alloy.

  8. A distributed optical fiber sensor for hydrogen detection based on Pd, and Mg alloys

    NARCIS (Netherlands)

    Perrotton, C.; Slaman, M.; Javahiraly, N.; Schreuders, H.; Dam, B.; Meyrueis, P.

    2010-01-01

    An optical fiber containing structured hydrogen sensing points, consisting of Palladium and/or Magnesium alloys is proposed and characterized. The sensitive layer is deposited on the outside of a multimode fiber, after removing the optical cladding. The sensor is based on a measurement technique whi

  9. Corrosion properties of plasma deposited nickel and nickel-based alloys

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Pražák, M.; Kalabisová, E.; Kreislová, K.; Had, J.; Neufuss, Karel

    2003-01-01

    Roč. 48, č. 3 (2003), s. 215-226. ISSN 0001-7043 R&D Projects: GA ČR GA106/99/0298 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma deposits, nickel , nickel -based alloys Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  10. Magnetic damping constant in Co-based full heusler alloy epitaxial films

    International Nuclear Information System (INIS)

    Co-based full-Heusler alloys, such as Co2MnSi and Co2MnGe, are expected to be used as half-metallic ferromagnetic material, which has complete spin polarization. They are the most promising materials for realizing half-metallicity at room temperature due to their high Curie temperature. The optimization of the magnetic damping constant of ferromagnetic materials is extremely important for achieving high-speed magnetization switching and reducing critical current density for spin torque transfer switching. We have systematically investigated the magnetic damping constant in Co-based full Heusler alloy epitaxial films. We found that the Gilbert damping constant seems to be roughly proportional to the total density of states at the Fermi level (EF) by first principle calculation. A very small magnetic damping constant of 0.003 in the Co2Fe0.4Mn0.6Si epitaxial film was demonstrated. The small magnetic damping constant in Co2FexMn1−xSi films with x < 0.6 can be attributed to the half-metallicity of Heusler alloys. Co-based full Heusler alloys with both half-metallicity and small magnetic damping will be very useful for future applications based on spintronic devices. (paper)

  11. Hard recharging. Metallurgical characteristics and use properties of hard recharging deposited by based cobalt alloys melting

    International Nuclear Information System (INIS)

    Hard recharging with cobalt base alloys are used in different parts of nuclear power plants. This paper presents mechanical properties, wear, thermal shock and corrosion resistances of hard coatings according to RCC-M S8000 rules, and explains relations between code recommendations and uses characteristics. (A.B.). 9 figs., 4 tabs

  12. Corrosion behaviour, microstructure and phase transitions of Zn-based alloys

    Indian Academy of Sciences (India)

    A K Yildiz; M Kaplan

    2004-08-01

    This paper is aimed at investigating the corrosion behaviour, microstructure and phase transitions of Zn-based alloys with different compositions. The corrosion tests are carried out both in acidic medium using 1 N HCl solution and in temperature dependence of thermogravimetric analysis (TGA). In the two different media, in particular, the corrosion behaviour of Zn-based alloys with respect to Al and Si contents is examined, and microstructure in acidic and TGA and phase transformations in TGA are also studied. Corrosion mechanism in TGA is also examined in terms of oxidation parameters and activation energies. The study reveals that corrosion behaviour of Zn-based alloys in acidic medium shows sometimes an increase and sometimes a decrease with time due to Al content which assists in delaying the corrosion by forming a oxide layer on the surface of Zn-based alloys. This property does not appear in temperature dependence of TGA. Further, Si content appears to remain in main matrix without being affected by acidic solution. On the other hand, it is observed that in microstructure, AlO(Al2O3), ZnO oxides and Zn–Cu phase precipitations are formed in main matrix, grain boundaries and partially inside the grains.

  13. The analysis of Al-based alloys by calorimetry: quantitative analysis of reactions and reaction kinetics

    OpenAIRE

    Starink, M.J.

    2004-01-01

    Differential scanning calorimetry (DSC) and isothermal calorimetry have been applied extensively to the analysis of light metals, especially Al based alloys. Isothermal calorimetry and differential scanning calorimetry are used for analysis of solid state reactions, such as precipitation, homogenisation, devitrivication and recrystallisation; and solid–liquid reactions, such as incipient melting and solidification, are studied by differential scanning calorimetry. In producing repeatable calo...

  14. ZnO-based semiconductors studied by Raman spectroscopy. Semimagnetic alloying, doping, and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schumm, Marcel

    2009-07-01

    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles). (orig.)

  15. Application of feal intermetallic phase matrix based alloys in the turbine components of a turbocharger

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2015-01-01

    Full Text Available This paper presents a possible application of the state-of-the-art alloys based on the FeAl intermetallic phases as materials for the manufacture of heat-proof turbine components in an automobile turbocharger. The research was aimed at determining the resistance to corrosion of Fe40Al5CrTiB alloy in a gaseous environment containing 9 % O2 + 0,2 % HCl + 0,08 % SO2 + N2. First the kinetics of corrosion processes for the considered alloy were determined at the temperatures of 900 °C, 1 000 °C and 1 100 °C, which was followed by validation under operating conditions. To do so, the tests were carried out over a distance of 20 000 km. The last stage involved examination of the surfaces after the test drive. The obtained results are the basis for further research in this field.

  16. The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells.

    Directory of Open Access Journals (Sweden)

    Nezha Ahmad Agha

    Full Text Available Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity.

  17. EFFECT OF TESTING ENVIRONMENT ON FRACTURING BEHAVIOR OF Fe3Si BASED ALLOY

    Institute of Scientific and Technical Information of China (English)

    J.H. Peng; G.L. Chen

    2003-01-01

    The mechanical behavior of Fe3Si based alloy with B2 structure was studied by tensionand fracture toughness test in various testing media. The fracture strength σb ofFe3Si alloy decreased in the following order: oxygen, air and hydrogen respectively.The fracture toughness in different testing environment showed that KiC in oxygenis 11.5±0.3MPa. m1/2, and is 8.6±0.4MPa. m1/2 in distilled water. The reductionof fracture toughness is contributed to the environmental reaction of Si with water.Addition of Al element in Fe3Si is not beneficial to improve the intrinsic ductility ofFe-14Si-3Al alloy. The scattering phenomenon of fracture strength was found, andexplained by fracture mechanics. It was found by means of SEM that the fracture modechanged from transgranular in oxygen to intergranular in hydrogen gas and distilledwater.

  18. Thermodynamics of several lewis-acid-base stabilized transition metal alloys

    Science.gov (United States)

    Gibson, John K.; Brewer, Leo; Gingerich, Karl A.

    1984-11-01

    High-temperature (1425 to 2750 K) thermodynamic activities of one or both components of twenty-five binary alloys of a group IVB-VIB element (Ti, Zr, Hf, Nb, Ta, or W) with a platinum group element (Ru, Os, Ir, Pd, Pt, or Au) have been determined by equilibrating the alloy with the appropriate carbide and graphite, equilibrating with the nitride and nitrogen gas, or measuring the partial vapor pressure(s) thermogravimetrically or mass spectrometrically. The extraordinary stability of this class of transition metal alloy is attributed to a generalized Lewis-acid-base interaction involving valence d electrons, and the results of these investigations are interpreted within the context of this effect. Among the conclusions made are that a non-spherically-symmetrical crystal field significantly reduces the bonding effectiveness of certain valence d orbitals; the effect of the extent of derealization of these orbitals is also considered.

  19. Brazeability of a 3003 Aluminum alloy with Al-Si-Cu-based filler metals

    Science.gov (United States)

    Tsao, L. C.; Weng, W. P.; Cheng, M. D.; Tsao, C. W.; Chuang, T. H.

    2002-08-01

    Al-Si-Cu-based filler metals have been used successfully for brazing 6061 aluminum alloy as reported in the authors’ previous studies. For application in heat exchangers during manufacturing, the brazeability of 3003 aluminum alloy with these filler metals is herein further evaluated. Experimental results show that even at such a low temperature as 550 °C, the 3003 alloys can be brazed with the Al-Si-Cu fillers and display bonding strengths that are higher than 77 MPa as well. An optimized 3003 joint is attained in the brazements with the innovative Al-7Si-20Cu-2Sn-1Mg filler metal at 575 °C for 30 min, which reveals a bonding strength capping the 3003 Al matrix.

  20. Oxidation behavior of multiphase Mo5SiB2 (T2)-based alloys at high temperatures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two Mo5SiB2 (T2)-based alloys with nominal compositions of Mo-12.5Si-25B and Mo-14Si-28B (molar fraction, %)were prepared in an arc-melting furnace, and their oxidation kinetics from 1 000 to 1 300 ℃ were studied. The microstructures of the alloys were characterized by X-ray diffractometry(XRD) and scanning electron microscopy(SEM) with energy dispersive spectroscopy (EDS). The oxide scales of both alloys oxidized at 1 200 ℃ for 10 min, 2 h and 100 h were investigated by surface XRD and cross-sectional SEM-EDS. The results show that the matrix of both alloys consists of T2. The dispersions of Mo-12.5Si-25B alloy are Mo and Mo3Si, and the dispersions of Mo-14Si-28B alloy are Mo5Si3 (T1) and MoB. The cyclic oxidation kinetics data exhibit initial rapid mass loss followed by slow mass loss. The mass loss of Mo-12.5Si-25B alloy is much faster than that of Mo-14Si-28B alloy at 1 200 and 1 300 ℃. For 10 min exposure, both alloys form irregular and porous thin scale. For 2 h exposure, Mo-12.5Si-25B alloy forms irregular thin scale and the scale contains large cracks, and Mo-14Si-28B alloy forms sound and continuous scale. For 100 h exposure, Mo-12.5Si-25B and Mo-14Si-28B alloys form sound and continuous scale about 50-75 μm and 40-45 μm in thickness, respectively. The better oxidation resistance of Mo-14Si-28B alloy is due to a sound and continuous B-SiO2 layer formation in the early stage of oxidation.

  1. Ambient-temperature high damping capacity in TiPd-based martensitic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Dezhen [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Yumei, E-mail: zhouyumei@mail.xjtu.edu.cn [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ding, Xiangdong [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Otsuka, Kazuhiro [Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan); Lookman, Turab [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sun, Jun [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan)

    2015-04-24

    Shape memory alloys (SMAs) have attracted considerable attention for their high damping capacities. Here we investigate the damping behavior of Ti{sub 50}(Pd{sub 50−x}D{sub x}) SMAs (D=Fe, Co, Mn, V) by dynamic mechanical analysis. We find that these alloys show remarkably similar damping behavior. There exists a sharp damping peak associated with the B2–B19 martensitic transformation and a high damping plateau (Q{sup −1}~0.02–0.05) over a wide ambient-temperature range (220–420 K) due to the hysteretic twin boundary motion. After doping hydrogen into the above alloys, a new relaxation-type damping peak appears in the martensite phase over 270–360 K. Such a peak is considered to originate from the interaction of hydrogen atoms with twin boundaries and the corresponding damping capacity (Q{sup −1}~0.05–0.09) is enhanced by roughly twice that of the damping plateau for each alloy. Moreover, the relaxation peaks are at higher temperatures for the TiPd-based alloys (270–370 K) than for the TiNi-based alloys (190–260 K). We discuss the influence of hydrogen diffusion, mobility of twin boundaries and hydrogen–twin boundary interaction on the temperature range of the relaxation peak. Our results suggest that a martensite, with appropriate values for twinning shear and hydrogen doping level, provides a route towards developing high damping SMAs for applications in desired temperature ranges.

  2. Chemical compositions of four barium stars

    CERN Document Server

    Liang, Y C; Chen, Y Q; Qiu, H M; Zhang, B

    2003-01-01

    Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and HD 98839 are studied based on high resolution, high signal-to-noise Echelle spectra. Results show that all of them are disk stars. Their \\alpha and iron peak elements are similar to the solar abundances. The neutron-capture process elements are overabundant relative to the Solar. The heavy-element abundances of the strong Ba star HD 50082 are higher than those of other three mild Ba stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD 26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun (+0.75,-0.78M_sun), respectively, which are consistent with the average mass of mild Ba stars. We also calculate the theoretical abundances of Ba stars by combining the AGB stars nucleosynthesis and wind accretion formation scenario of Ba binary systems. The comparisons between the observed abundance patterns of the sample stars with the th...

  3. Fuel behavior in severe accidents and Mo-alloy based cladding designs to improve accident tolerance

    International Nuclear Information System (INIS)

    The severe accidents at TMI-2 and Fukushima-Daiichi led to core meltdown and hydrogen explosions. The main source of energy causing core melting is the decay heat from β-, β+, and γ decays of short-lived isotopes following a power scram. The exothermic reaction of Zr-alloy cladding can further increase the cladding temperature leading to rapid cladding corrosion and hydrogen production. The most effective mitigation to minimize core damage in a severe accident is to extend the duration of heat removal capacity via battery-supported passive cooling for as long as practically possible. Replacing the Zr-alloy cladding with a higher heat resistant cladding with lower enthalpy release rate may also provide additional coping time for accident management. Such a heat resistant cladding may also overcome the current licensing concerns about Zr-alloy hydriding and post quench ductility issues in a design base loss of coolant accident (LOCA). Zr-alloy cladding, while has been optimized for normal operation in high pressure water and steam of light water reactors, will rapidly lose its corrosion resistance and tensile and creep strength in high pressure steam. Evaluation of alternate cladding materials and designs have been performed to search for a new fuel cladding design which will substantially improve the safety margins at elevated temperatures during a severe accident, while maintaining the excellent fuel performance attributes of the current Zr-alloy cladding. The screening criteria for the evaluation include neutronic properties, material availability, adaptability and operability in current LWRs, resistance to melting. The new designs also need to be fabricable, maintain sufficient strength and resist to attack by high pressure steam. Engineering metals, alloys and ceramics which can meet some or most of these requirements are limited. Following review of the properties of potential candidates, it is concluded that molybdenum alloys may potentially achieve the

  4. Unusual glass-forming ability of new Zr-Cu-based bulk glassy alloys containing an immiscible element pair

    International Nuclear Information System (INIS)

    We herein report the unusual glass-forming ability (GFA) of a new series of quinary Zr48Cu36-xNixAg8Al8 (048Cu36Ag8Al8 alloy. By cooper mold casting, an as-cast glassy rod with a diameter of 30 mm can be easily obtained for the representative alloy Zr48Cu32Ni4Ag8Al8. The possible reasons for the excellent GFA of the new quinary alloys with an immiscible element pair are discussed based on the atomic size distribution, chemical compatibility among the components and atomic structure of glassy alloys. (author)

  5. Phonon dispersion in alkali metals and their equiatomic sodium-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    Aditya M. VORA

    2008-01-01

    In the present article, the theoretical calcula-tions of the phonon dispersion curves (PDCs) of five alkali metals viz. Li, Na, K, Rb, Cs and their four equia-tomic sodium-based binary alloys viz. Na0.5Li0.5,Na0.5K0.5, Na0.5Rb0.5 and Na0.5Cs0.5 to second order in a local model potential is discussed in terms of the real-space sum of the Born yon Karman central force con-stants. Instead of the concentration average of the force constants of pure alkali metals, the pseudo-alloy-atom (PAA) is adopted to directly compute the force constants of the four equiatomic sodium based binary alloys and was successfully applied. The exchange and correlation functions due to the Hartree (H) and Ichimaru-Utsumi (IU) are used to investigate the influence of the screening effects. The phonon frequencies of alkali metals and their four equiatomic sodium-based binary alloys in the longit-udinal branch are more sensitive to the exchange and cor-relation effects in comparison with the transverse branches. The PDCs of pure alkali metals are found in qualitative agreement with the available experimental data. The frequencies in the longitudinal branch are sup-pressed rather due to IU-screening function than those due to static H-screening function.

  6. Skylab-barium alpha and beta L = 6 field-line tracing experiments

    International Nuclear Information System (INIS)

    Events SKYLAB-BARIUM ALPHA (27 November 1973) and BETA (4 December 1973) were shaped-charge barium field-line tracing experiments near L approximately equal to 6, conducted jointly by the Los Alamos Scientific Laboratory and the University of Alaska Geophysical Institute. Image-orthicon and pulsed intensified auroral cameras provided data for triangulating the fast ion streaks. Using the POGO 10-68, epoch 1965.0, field-line model with Mead-Fairfield corrections for the outer field, the triangulated positions of the fast ion streak were projected down to the 100 km altitude northern conjugate surface. The projected positions moved toward magnetic east with a velocity of 725 m/sec for both SKYLAB-BARIUM ALPHA and BETA. Assuming only an E x B/B2 force, this drift velocity is consistent with an electric field toward magnetic south of 39 mV/m. Radiometric analysis of the filtered, intensified auroral camera records gave observed peak radiance values of about 2 x 10-11 watts/cm2-Sr in the 455.4 nm line of Ba+. The barium in the portion of the ion streak for which radiometric data were obtained had initial injection velocities of 9.5 to 13.5 km/sec in both events. This portion of the ion streak for both SKYLAB-BARIUM ALPHA and BETA contained approximately 4 x 1023 ions compared to the 6.4 x 1024 atoms contained in the barium liner. Ion inventory estimates are based on a solution of the statistical equilibrium equations. Corrections have been made in the ion inventory calculations for Doppler shifts of the solar spectrum as received in the rest frame of the high-velocity barium ions

  7. Ni-Cr based dental alloys; Ni release, corrosion and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Reclaru, L., E-mail: lucien.reclaru@pxgroup.com [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Unger, R.E.; Kirkpatrick, C.J. [Institute for Pathology, REPAIR Lab, University Medical Center, Johannes Gutenberg University Mainz, Langenbeckstr.1, D-55101 Mainz (Germany); Susz, C.; Eschler, P.-Y.; Zuercher, M.-H. [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Antoniac, I. [Materials Science and Engineering Faculty, Politehnica of Bucharest, 060042 Bucharest (Romania); Luethy, H. [Institute of Dental Materials Science and Technology, University of Basel, Hebelstrasse 3, CH-4056 Basel (Switzerland)

    2012-08-01

    In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys. In Europe the prevalence of nickel allergy is 10-15% for female adults and 1-3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni-Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys. We have collected based on many EU markets, 8 Ni-Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted. According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing. Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction. We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects. - Highlights: Black-Right-Pointing-Pointer Nickel released was higher than the limits imposed in EU in contact with the skin. Black-Right-Pointing-Pointer No direct relationship between the

  8. Ni–Cr based dental alloys; Ni release, corrosion and biological evaluation

    International Nuclear Information System (INIS)

    In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys. In Europe the prevalence of nickel allergy is 10–15% for female adults and 1–3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni–Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys. We have collected based on many EU markets, 8 Ni–Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted. According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing. Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction. We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects. - Highlights: ► Nickel released was higher than the limits imposed in EU in contact with the skin. ► No direct relationship between the biological evaluation and chemical degradation.

  9. On the nature of the variation of martensitic transformation hysteresis and SME characteristics in Fe-Ni-base alloys

    International Nuclear Information System (INIS)

    The purpose of this paper is to summarize the various investigations, both by the authors and other works, concerning with the martensitic transformation and SME in Fe-Ni-base alloys. The thermal hysteresis dependence on the alloying elements and thermal treatments are surveyed. The contribution and effect on SME characteristics of widely used alloying elements such as Ti, Nb, Ni, Al, Co, Ta and peculiarities of thermal treatment are discussed. It is noted the main goal of these treatments is to reduce the symmetry of transformation by the ordering or precipitation of a fine coherent phase. The physical principles of transformation hysteresis manipulation in Fe-base alloys is discussed and it concluded that the thermal cycling behavior of Fe-base alloys is very complex and is not clearly understood at present. On the other hand, it is pointed out that thermal cycling is an effective method for control and improvement of SME in these alloys. It is concluded that Fe-base alloys are highly evolved shape memory materials-having a wide working range, good workability and are relatively cheap. In addition, the properties are easily controlled by suitably alloying, aging and thermal cycling. (orig.)

  10. Frenkel defects in Ni and Ni-base alloys

    International Nuclear Information System (INIS)

    The defect structure produced by low temperature (4K) electron irradiation in single crystals of Ni, Ni62Cu38 and Ni3 Fe was investigated by measurements of the diffuse scattering of X-rays (Huang Diffuse Scattering), the change of the lattice parameter and the change of the electrical resistivity: The volume relaxation and the structure of the self interstitial atom (SIA) is very similar for the alloys and the pure fcc metals. The interstitial clustering processes during stage I and II proceed progressively more slowly in Cu, Ni, NiCu and Ni3Fe respectively. In Ni3Fe even the di-interstitial seems immobile up to stage III. The formation of large vacancy agglomerates during stage III annealing is only observed with the pure metals Ni and Cu. Interstitial mobility during annealing in stage II contributes to the decomposition of NiCu but not to the ordering of Ni3Fe. There is an increase of order for highly ordered Ni3Fe (S = 0.7) during annealing in stage III and, within the errors, no change for samples with S = 0. (author)

  11. Hydrogen distribution in amorphous silicon and silicon based alloys

    International Nuclear Information System (INIS)

    The results of hydrogen evolution experiments on amorphous silicon alloys prepared by high frequency PECVD of gas mixtures containing SiH4, NH3, PH2, B2H6 are compared. Using a very low heating rate of 5 degree/min it is possible to resolve fine structure on the exodiffusion spectra. Three evolution processes are observed: (a) low temperature effusion due to included gas (b) mid temperature effusion due to 'clustered' hydrogen bonds (c) high temperature effusion due to 'isolated' hydrogen bonds In addition it is possible to oberve very fine structure 'puffing' due to the release of molecular hydrogen at mid to high temperature. Silicon and silicon nitride films have been annealed at low temperatures before the exodiffusion experiments and changes in the evolution spectra are observed, dependent on the annealing process. A scanning electron microscope study of the effect of high temperature heat treatment has also been undertaken. These results are correlated with infra-red absorption measurements and the influence of doping concentration and substrate character discussed. Under certain preparation conditions the films blister on heating and finally burst forming circular craters, and these effects are shown to be dependent on substrate material and intrinsic stress of the as-grown films

  12. The surface layer degradation of γ-TiAl phase based alloy

    Directory of Open Access Journals (Sweden)

    J. Małecka

    2013-05-01

    Full Text Available Purpose: The aim of the present research is to describe the chemical composition and microstructure of the surface layer of Ti-46Al-7Nb-0.7Cr-0,1Si-0.2Ni alloy after the test of isothermal oxidation in 9%O2+0.2%HCl+0.08%SO2+N2 during 250 h. Design/methodology/approach: The objectives were achieved using several techniques including conventional metallography, SEM, BSE, EDX. The oxides scales and their effects were investigated at temperatures 750ºC.Findings: This investigation confirms that the better protection of the substrate was determined using AlCrN coating.Research limitations/implications: The basic limitations concern alloys in a higher temperature and establish the oxidation kinetics of the analysed alloy as a function of time and temperature.Practical implications: One of practical outcomes is to select the coatings which guarantee the reduction of oxidation behavior. It is recommended to use alloys with AlCrN coating.Originality/value: Original value of the paper is assessing of the oxidation resistance of Ti-46Al-7Nb-0.7Cr-0.1Si–0.2Ni-based intermetallic alloy at the conditions combining high temperature and sulphur and chlorine compounds-containing atmosphere. The novelty of this research deals with the mechanism of oxidation at such boundary conditions. This knowledge can support the design of parts made of the intermetallic alloy. The problem considered is currently important for aeroplane and automotive industry, especially for gas turbine manufacturers.

  13. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  14. Coprecipitation of iron and silver with barium fluoride

    International Nuclear Information System (INIS)

    Distribution of trace contaminants of iron and silver at coprecipitation of barium fluoride is studied in present work. It is defined that iron almost completely coprecipitated with barium fluoride in wide range of ph 5.5-12. Silver coprecipitated with barium fluoride in ph range 4-7. The value of coprecipitation varies from 94% to 100%.

  15. Research on CMT welding of nickel-based alloy with stainless steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cold Metal Transfer (CMT) welding technique is a new welding technique introduced by Fronius company. CMT welding of nickel-based alloy with stainless steel was carried out using CuSi3 filler wire in this paper. Effects of welding parameters, including welding current, welding speed, etc, on weld surface appearance were tested. Microstructure and mechanical properties of CMT weld were studied. The results show that the thickness of interface reaction layer of the nickel-based alloy is 14.3μm, which is only 4.33% of base material. The weld is made up of two phases,α-copper and iron-based solid solution. Rupture occurs initially at the welded seam near the edge of stainless steel in shear test. The maximum shear strength of the CuSi3 welded joint is 184.9MPa.

  16. The electronic mechanism of the γ/γ' interface strength of Ir-based alloys

    International Nuclear Information System (INIS)

    The electronic structures of the γ/γ' interface for two-phase Ir-based alloys (Ir/Ir3Ta and Ir/Ir3Ti) have been investigated by performing first-principles quantum mechanics DMol3 (a type of density functional theory for molecules) calculations. The Mayer bond order (MBO) is used to represent the shear and cohesion strengths of the interface by a local sum of the horizontal and vertical MBOs. By comparison with those for single-crystal Ir, the results show that both the cohesive and shear strengths of the γ/γ' interface for the Ir/Ir3Ta alloy increase. The cohesive strength of the interface for the Ir/Ir3Ti alloy increases, whereas the shear strength of the interface for Ir/Ir3Ti decreases. The electron charge density, the Hirshfeld charge, and orbital charge transfers are also calculated and analysed. An electronic mechanism for the γ/γ' interface strength of Ir-based alloys is then suggested

  17. Fundamental aspects of corrosion on zirconium base alloys in water reactor environments

    International Nuclear Information System (INIS)

    The purpose of this meeting was to discuss the state of knowledge of zirconium alloy corrosion mechanisms. Forty-five participants from 16 countries attended the meeting, and 25 papers were presented and discussed. One additional paper was provided only in written form. The papers were presented in seven sub-sessions under the following headings: Electrochemistry, Coolant Chemistry Effects, Irradiation Effects, Characteristics of Zirconium Oxide, Effects of Alloying on Corrosion, Corrosion Modeling and Effect of Zirconium Base Metal Properties on Corrosion. There is still a need for a laboratory corrosion test that reliably predicts in-pile corrosion in BWR's and PWR's. This holds particularly if out-of-pile tests are used for developing new Zr base alloy compositions. The role of the precipitates and of the solute elements in the matrix has still to be clarified. As it appears, a combination of both influences is necessary to explain the mechanistic aspect of the corrosion of Zircaloy. It is clear that mechanistic understanding of zirconium alloy corrosion is still some way off, although a significant amount of progress has been made toward experimental determination of the micro-scale phenomena. The papers presented a status report of our knowledge of these corrosion mechanisms, but they also served to illustrate the fact that much of the work done to date has been phenomenological rather than mechanistic. The summaries of individual sessions detail the specific conclusions and recommendations made at the meeting. Refs, figs and tabs

  18. Solid particle erosion of steels and nickel based alloys candidates for USC steam turbine blading

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, Federico; Guardamagna, Cristina; Lorenzoni, Lorenzo [ERSE SpA, Milan (Italy); Robba, Davide [CESI, Milan (Italy)

    2010-07-01

    The main objective of COST536 Action is to develop highly efficient steam power plant with low emissions, from innovative alloy development to validation of component integrity. In this perspective, to improve the operating efficiency, materials capable of withstanding higher operating temperatures are required. For the manufacturing of components for steam power plants with higher efficiency steels and nickel-based alloys with improved oxidation resistance and creep strength at temperature as high as 650 C - 700 C have to be developed. Candidate alloys for manufacturing high pressure steam turbine diaphragms, buckets, radial seals and control valves should exhibit, among other properties, a good resistance at the erosion phenomena induced by hard solid particles. Ferric oxide (magnetite) scales cause SPE by exfoliating from boiler tubes and steam pipes (mainly super-heaters and re-heaters) and being transported within the steam flow to the turbine. In order to comparatively study the erosion behaviour of different materials in relatively short times, an accelerated experimental simulation of the erosion phenomena must be carried out. Among different techniques to induce erosion on material targets, the use of an air jet tester is well recognised to be one of the most valid and reliable. In this work the results of SPE comparative tests performed at high temperatures (550 C, 600 C and 650 C) at different impaction angles on some steels and nickel based alloys samples are reported. (orig.)

  19. A study of electron beam welding of Mo based TZM alloy

    International Nuclear Information System (INIS)

    Mo based TZM alloy is one of the most promising refractory alloy having several unique high temperature properties suitable for structural applications in the new generation advanced nuclear reactors. However, this alloy easily picks up interstitial impurities such as N2, H2 and C from air during welding due to its reactive nature. High melting point of TZM alloy also restricts use of conventional welding technique for welding. Hence, Electron beam welding (EBW) technique with its deep penetration power to produce narrow heat affected zones under high vacuum was employed to overcome the above welding constraints by conducting a systematic study using both processes of bead on plate and butt joint configuration. Uniform and defect free weld joints were produced. Weld joints were subjected to optical characterization, chemical homogeneity analysis and microhardness profile study across the width of welds. Improved grain structure with equiaxed grains was obtained in the weld zone as compared to fibrous base structure. Original chemical composition was retained in the weld zone. The detailed results are described in this report. (author)

  20. Optical modeling of nickel-base alloys oxidized in pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2012-10-01

    The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratification model was determined using focused ion beam cross-section of thin foils examined by transmission electron microscopy. Dielectric constants of the inner oxide layer depleted in chromium were assimilated to those of the nickel thin film. The optical constants of both the spinels and extern layer were determined. - Highlights: Black-Right-Pointing-Pointer Spectroscopic ellipsometry of Ni-base alloy oxidation in pressurized water reactor Black-Right-Pointing-Pointer Measurements of the dielectric constants of the alloys Black-Right-Pointing-Pointer Optical simulation of the mixed oxidation process using a three stack model Black-Right-Pointing-Pointer Scattered crystallites cationic outer layer; linear Ni-gradient bottom layer Black-Right-Pointing-Pointer Determination of the refractive index of the spinel and the Cr{sub 2}O{sub 3} layers.

  1. Modeling of self-controlling hyperthermia based on nickel alloy ferrofluids: Proposition of new nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Delavari, H. Hamid, E-mail: Hamid.delavari@gmail.com [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Madaah Hosseini, Hamid R. [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Wolff, Max, E-mail: Max.wolff@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

    2013-06-15

    In order to provide sufficient heat without overheating healthy tissue in magnetic fluid hyperthermia (MFH), a careful design of the magnetic properties of nanoparticles is essential. We perform a systematic calculation of magnetic properties of Ni-alloy nanoparticles. Stoner–Wohlfarth model based theories (SWMBTs) are considered and the linear response theory (LRT) is used to extract the hysteresis loop of nickel alloy nanoparticles in alternating magnetic fields. It is demonstrated that in the safe range of magnetic field intensity and frequency the LRT cannot be used for the calculation of the area in the hysteresis for magnetic fields relevant for hyperthermia. The best composition and particle size for self-controlling hyperthermia with nickel alloys is determined based on SWMBTs. It is concluded that Ni–V and Ni–Zn are good candidates for self-controlling hyperthermia. - Highlights: ► Systematic calculation of magnetic properties of Ni-alloy NPs with composition has been performed. ► Optimum composition and particle size for self-controlling hyperthermia (SCH) have been determined. ► Ni–V and Ni–Zn nanoparticles are more appropriate candidates for SCH.

  2. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    Science.gov (United States)

    Abdal-hay, Abdalla; Dewidar, Montasser; Lim, Jae Kyoo

    2012-11-01

    The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  3. Recrystallization of 223Ra with barium sulfate

    International Nuclear Information System (INIS)

    In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm-3 sodium sulfate solution using 223Ra and 133Ba tracers at very low total radium concentration, i.e. less than 10-13 mol dm-3. It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of 223Ra and 133Ba in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate-a mineral present in the deep underground repository. (author)

  4. Printed Barium Strontium Titanate capacitors on silicon

    International Nuclear Information System (INIS)

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography

  5. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  6. The creep Kinetics of sand cat zinc-based alloys no. 2, ACuZinc5, and ACuzinc10

    International Nuclear Information System (INIS)

    Compressive creep tests have been carried out on three sand cast zinc-rich alloys No. 2 (Zn-4% Al-2.8% Cu 0.03% Mg), ACuZinc5 (Zn-3% Al-5.2% Cu-0.04% Mg) and ACuZinc10 (Zn-3.5% Al-9.3% Cu-0.03% Mg) in the stress range 20 to 100 MPa, and at temperatures from 70 to 160 deg. centigrade. The tests were performed on a standard weight lever arm compressive creep machine. Alloy No. 2 is a conventional zinc alloy, whereas ACuZinc5 and ACuZinc10 belong to a family of new, GM-patented, high performance ternary zin-copper-aluminium alloys which are suitable for manufacturing net shape die castings. Along with creep, other properties of ACuZinc alloys are claimed to be better than conventional zinc alloys No. 3 and No. 5 and ZA alloys, i.e. ZA.8, ZA.12 and ZA.27. A parametric relationship was obeyed, of the form:In t=C-n(In sigma)+Q/RTm where C is a constant, sigma the applied stress, t time of test, n the stress exponent, Q the activation energy, R the gas constant, and T is the absolute temperature. The primary creep contraction was generally found to increase with increasing copper content, but in a non-linear fashion. The secondary creep rates of alloy No. 2 were slightly lower than those of ACuZinc5 and ACuZinc10. Based on the above equation, continuous design stresses were calculated under different testing conditions which showed that both ACuZinc alloys were inferior in creep strength to alloy No.2 due to its lower secondary creep rates. The results and microstructure of alloys also showed that in all three alloys, the creep-controlling mechanism is the dislocation climb over second-phase (Epsilon) particles. (author)

  7. Development of an Electromagnetic Wave Shielding Textile by Electroless Ni-Based Alloy Plating

    OpenAIRE

    Sonehara, Makoto; Noguchi, Shin; Kurashina, Tadashi; Sato, Toshiro; YAMASAWA, Kiyohito; Miura, Yoshimasa

    2009-01-01

    A polyester nonwoven textile with Ni-based alloy coating was fabricated, and the effect of electromagnetic wave shielding was evaluated. The Ni-based was coated by electroless plating on the textile. The electromagnetic wave shielding effect of the textile with Ni-B coating was about 99.98% over the induction range of 6-13 GHz. Because the textile has thin, light, flexible, and breathable characteristics, it will be versatile for the various electromagnetic wave shielding applications.

  8. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy.

    Science.gov (United States)

    Dang, B; Zhang, X; Chen, Y Z; Chen, C X; Wang, H T; Liu, F

    2016-01-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy. PMID:27502444

  9. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

    Science.gov (United States)

    Dang, B.; Zhang, X.; Chen, Y. Z.; Chen, C. X.; Wang, H. T.; Liu, F.

    2016-08-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

  10. Thermodynamic prediction of thixoformability in alloys based on the Al-Si-Cu and Al-Si-Cu-Mg systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Atkinson, H.V. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Jones, H. [Department of Engineering Materials, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2005-08-15

    Most commercial semi-solid processing (of which thixoforming is one type) utilises the conventional casting alloys A356 and A357. There is, however, a demand to widen the range of alloys, including those with higher performance which tend to show poor characteristics for thixoforming. Thermodynamic calculation packages, such as MTDATA, provide a tool for predicting thixoformability. Here, the effects of compositional variations, in particular the effect of added copper on the thixoformability of alloy A356 and the effect of added silicon on the thixoformability of alloy 2014, have been investigated using MTDATA thermodynamic and phase equilibrium software combined with the MTAL database. Criteria for thixoformability are identified and a range of alloy compositions based on Al-Si-Cu and Al-Si-Cu-Mg evaluated in relation to these criteria. Compositions which satisfy these criteria include: 308 (Al-5.5Si-4.5Cu); 319 (Al-6Si-3.5Cu); 238 (Al-10Cu-4Si-0.3Mg); 355 (Al-5Si-1.3Cu-0.5Mg); 2014 based alloys Al-4.4Cu-0.5Mg-(4-6)Si; and a range of alloys (7.5 Si + Cu 9 and 1.5 Si/Cu 2.33) and alloys (9 < Si + Cu 10 and Si/Cu = 1.5) based on the Al-Si-Cu-Mg system.

  11. The kinetics of phase transformations of undercooled austenite of the Mn-Ni iron based model alloy

    Directory of Open Access Journals (Sweden)

    E. Rożniata

    2011-12-01

    Full Text Available Purpose: Present work corresponds to the research on the kinetics of phase transformations of undercooled austenite of Mn-Ni iron based model alloy. The kinetics of phase transformations of undercooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation. Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described.Design/methodology/approach: The austenitising temperature was defined in a standard way i.e. 30-50°C higher than Ac3 temperature for model alloy. A technique of full annealing was proposed for the model alloy. The CCT diagrams were made on the basis of dilatograms recorded for samples cooled at various rates. The microstructure of each dilatometric sample was photographed after its cooling to the room temperature and the hardness of the samples was measured.Findings: The test material was a Mn-Ni hypoeutectoid iron based alloy. The microstructure of test Mn-Ni alloy on CCT diagram changes depending on the cooling rate. At the cooling rates of 10°C/s and 5°C/s there is ferrite in Widmannstätten structure present in the structure of tested alloy.Research limitations/implications: The new Mn-Ni iron based model alloy and a new CCT diagram.Practical implications: The paper contains a description of one from a group of iron based model alloys with 0.35-0.40% carbon content. According to PN-EN 10027 standard this steel should have a symbol 38MnNi6-4.Originality/value: The new Mn-Ni iron based model alloy.

  12. The resistance to embrittlement by a hydrogen environment of selected high strength iron-manganese base alloys

    Science.gov (United States)

    Benson, R. B., Jr.; Kim, D. K.; Atteridge, D.; Gerberich, W. W.

    1974-01-01

    Fe-16Mn and Fe-25Mn base alloys, which had been cold worked to yield strength levels of 201 and 178 KSI, were resistant to degradation of mechanical properties in a one atmosphere hydrogen environment at ambient temperature under the loading conditions employed in this investigation. Transmission electron microscopy established that bands of epsilon phase martensite and fcc mechanical twins were formed throughout the fcc matrix when these alloys were cold worked. In the cold worked alloys a high density of crystal defects were observed associated with both types of strain induced structures, which should contribute significantly to the strengthening of these alloys. High strength iron base alloys can be produced which appear to have some resistance to degradation of mechanical properties in a hydrogen environment under certain conditions.

  13. Chromium activity measurements in nickel based alloys for very high temperature reactors: Inconel 617, haynes 230 and model alloys - HTR2008-58147

    International Nuclear Information System (INIS)

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHX) of (V)-HTR reactors. The behaviour under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer Then, the alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow [1]. To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T∼1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617 and model alloys 1178, 1181, 1201. This coupling makes it possible thermodynamic equilibrium to be obtained between the vapour phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (/) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared to that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behaviour in these alloys. These activity results call into question those previously measured by Hilpert [2], largely used in the literature. (authors)

  14. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, N.G. [University of Otago, Department of Radiology, Christchurch (New Zealand); Butler, A.P. [University of Otago, Department of Radiology, Christchurch (New Zealand); University of Canterbury, Physics and Astronomy, Christchurch (New Zealand); Scott, N.J.A. [University of Otago, Department of Medicine, Christchurch (New Zealand); Cook, N.J. [Christchurch Hospital, Medical Physics and Bioengineering, Christchurch (New Zealand); Butzer, J.S. [Karlsruhe Institute of Technology, Physics Department, Karlsruhe (Germany); Schleich, N. [University of Canterbury, Physics and Astronomy, Christchurch (New Zealand); Christchurch Hospital, Medical Physics and Bioengineering, Christchurch (New Zealand); Firsching, M. [Friedrich Alexander University, Physics Department, Erlangen (Germany); Grasset, R.; Ruiter, N. de [University of Canterbury, Hitlab NZ, Christchurch (New Zealand); Campbell, M. [European Organisation for Nuclear Research, Physics Section, Geneva (Switzerland); Butler, P.H. [University of Canterbury, Physics and Astronomy, Christchurch (New Zealand)

    2010-09-15

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 {mu}A). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct from soft tissue and bone in all six mice. Calcium, iodine and barium were displayed as separate channels on 3D colour images at <55 {mu}m isotropic voxels. Spectral CT distinguishes contrast agents with K-edges only 4 keV apart. Multi-contrast imaging and molecular CT are potential future applications. (orig.)

  15. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE

    International Nuclear Information System (INIS)

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 μA). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct from soft tissue and bone in all six mice. Calcium, iodine and barium were displayed as separate channels on 3D colour images at <55 μm isotropic voxels. Spectral CT distinguishes contrast agents with K-edges only 4 keV apart. Multi-contrast imaging and molecular CT are potential future applications. (orig.)

  16. Qualification of new filler metal made of high chromium content nickel base alloy

    International Nuclear Information System (INIS)

    A study has been carried out by EDF and FRAMATOME in the context of the French Association for design and manufacturing rules of nuclear power boiler's equipment, to research then qualify filler metals dedicated to the welding of the new nickel base including 30 % chromium alloy components of PWR. The aim is to assess their weldability and their stress corrosion behaviour in the conditions prevailing in the primary cooling system of PWR and to compare with products generally used. Moreover, numerous qualification tests have been carried out to verify that such metals meet the criteria accepted in the RCC-M code. Results allowed to qualify some filler metals made of nickel base alloy of qualify equivalent to the one of NC30Fe including 30 % chromium base metals. These metals are at present time used in manufacturing. (authors). 5 figs

  17. Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Aghamiri, S.M. [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Shahverdi, H.R., E-mail: Shahverdi@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S. [Material Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8626 (Japan); Okuda, T. [Kobelco Research Institute Ltd., Kobe 651-2271 (Japan)

    2015-02-15

    The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

  18. Sn-Sb-Se based binary and ternary alloys for phase change memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung-Min

    2008-10-28

    In this work, the effect of replacing Ge by Sn and Te by Se was studied for a systematic understanding and prediction of new potential candidates for phase change random access memories applications. The temperature dependence of the electrical/structural properties and crystallization kinetics of the Sn-Se based binary and Sn-Sb-Se based ternary alloys were determined and compared with those of the GeTe and Ge-Sb-Te system. The temperature dependence of electrical and structural properties were investigated by van der Pauw measurements, X-ray diffraction, X-ray reflectometry. By varying the heating rate, the Kissinger analysis has been used to determine the combined activation barrier for crystallization. To screen the kinetics of crystallization, a static laser tester was employed. In case of binary alloys of the type Sn{sub x}Se{sub 1-x}, the most interesting candidate is SnSe{sub 2} since it crystallizes into a single crystalline phase and has high electrical contrast and reasonably high activation energy for crystallization. In addition, the SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloy system also might be sufficient for data retention due to their higher transition temperature and activation energy for crystallization in comparison to GeTe-Sb{sub 2}Te{sub 3} system. Furthermore, SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloys have a higher crystalline resistivity. The desired rapid crystallization speed can be obtained for Sn{sub 1}Sb{sub 2}Se{sub 5} and Sn{sub 2}Sb{sub 2}Se{sub 7} alloys. (orig.)

  19. Tantalum-based multilayer coating on cobalt alloys in total hip and knee replacement

    International Nuclear Information System (INIS)

    Cobalt–chromium–molybdenum (CoCrMo) alloys are widely used in total hip and knee joint replacement, due to high mechanical properties and resistance to wear and corrosion. They are able to form efficient artificial joints by means of coupling metal-on-polymer or metal-on-metal contacts. However, a high concentration of stress and direct friction between surfaces leads to the formation of polyethylene wear debris and the release of toxic metal ions into the human body, limiting, as a consequence, the lifetime of implants. The aim of this research is a surface modification of CoCrMo alloys in order to improve their biocompatibility and to decrease the release of metal ions and polyethylene debris. Thermal treatment in molten salts was the process employed for the deposition of tantalum-enriched coating. Tantalum and its compounds are considered biocompatible materials with low ion release and high corrosion resistance. Three different CoCrMo alloys were processed as substrates. An adherent coating of about 1 μm of thickness, with a multilayer structure consisting of two tantalum carbides and metallic tantalum was deposited. The substrates and modified layers were characterized by means of structural, chemical and morphological analysis. Moreover nanoindentation, scratch and tribological tests were carried out in order to evaluate the mechanical behavior of the substrates and coating. The hardness of the coated samples increases more than double than the untreated alloys meanwhile the presence of the coating reduced the wear volume and rate of about one order of magnitude. - Highlights: ► Thermal treatment in molten salts deposits a Ta-based coating on Co-based alloys. ► Coating is composed by one or two tantalum carbides and/or metallic tantalum. ► The coating structure depends on thermal temperature and substrates carbon content. ► Coating is able to enhance biocompatibility, wear resistance and hardness.

  20. Novel bioactive Co-based alloy/FA nanocomposite for dental applications

    Directory of Open Access Journals (Sweden)

    Mohammadhossein Fathi

    2012-01-01

    Full Text Available Background: Dental cobalt base alloys are biocompatible dental materials and have been widely used in dentistry. However, metals are bioinert and may not present bioactivity in human body. Bioactivity is the especial ability to interact with human body and make a bonding to soft and hard tissues. The aim of the present research was fabrication and bioactivity evaluation of novel cobalt alloy/Fluorapatite nanocomposite (CoA/FaNC with different amounts of Fluorapatite (FA nanopowder. Materials and Methods: Co-Cr-Mo alloy (ASTM F75 powder was prepared and mixed in a planetary ball mill with different amounts of FA nanopowders (10, 15, 20% wt. Prepared composite powders were cold pressed and sintered at 1100°C for 4 h. X-ray diffraction (XRD, scanning electron microscopy and transition electron microscopy techniques were used for phase analysis, crystallite size determination of FA and also for phase analysis and evaluation of particle distribution of composites. Bioactivity behavior of prepared nanocomposites was evaluated in simulated body fluid (SBF for 1 up to 28 days. Results: Results showed that nucleus of apatite were formed on the surface of the prepared CoA/FaNC during 1 up to 28 days immersion in the SBF solution. On the other hand, CoA/FaNC unlike Co-base alloy possessed bone-like apatite-formation ability. Conclusion: It was concluded that bioinert Co-Cr-Mo alloy could be successfully converted into bioactive nanocomposite by adding 10, 15, 20 wt% of FA nano particles.

  1. Stress corrosion cracking of nickel base alloys in PWR primary water

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of nickel base alloys and associated weld metals in primary water is one of the major concerns for pressurized water reactors (PWR). Since the 90's, highly cold-worked stainless steels (non-sensitized) were also found to be susceptible to SCC in PWR primary water ([1], [2], [3]). In the context of the life extension of pressurized water reactors, laboratory studies are performed in order to evaluate the SCC behaviour of components made of nickel base alloys and of stainless steels. Some examples of these laboratory studies performed at CEA will be given in the talk. This presentation deals with both initiation and propagation of stress corrosion cracks. The aims of these studies is, on one hand, to obtain more data regarding initiation time or crack growth rate and, one the other hand, to improve our knowledge of the SCC mechanisms. The aim of these approaches is to model SCC and to predict components life duration. Crack growth rate (CGR) tests on Alloy 82 with and without post weld heat treatment are performed in PWR primary water (Figure 1). The heat treatment seems to be highly beneficial by decreasing the CGR. This result could be explained by the effect of thermal treatment on the grain boundary nano-scopic precipitation in Alloy 82 [4]. The susceptibility to SCC of cold worked austenitic stainless steels is also studied. It is shown that for a given cold-working procedure, SCC susceptibility increases with increasing cold-work ([2], [5]). Despite the fact that the SCC behaviour of Alloy 600 has been widely studied for many years, recent laboratory experiments and analysis ([6], [7], [8]) showed that oxygen diffusion is not a rate-limiting step in the SCC mechanism and that chromium diffusion in the bulk close the crack tip could be a key parameter. (authors)

  2. Tantalum-based multilayer coating on cobalt alloys in total hip and knee replacement

    Energy Technology Data Exchange (ETDEWEB)

    Balagna, C., E-mail: cristina.balagna@polito.it [Institute of Materials Engineering and Physics, Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24,10129 Torino (Italy); Faga, M.G. [Istituto di Scienza e Tecnologia dei Materiali Ceramici, Consiglio Nazionale delle Ricerche, Strada delle Cacce 73, 10135 Torino (Italy); Spriano, S. [Institute of Materials Engineering and Physics, Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24,10129 Torino (Italy)

    2012-05-01

    Cobalt-chromium-molybdenum (CoCrMo) alloys are widely used in total hip and knee joint replacement, due to high mechanical properties and resistance to wear and corrosion. They are able to form efficient artificial joints by means of coupling metal-on-polymer or metal-on-metal contacts. However, a high concentration of stress and direct friction between surfaces leads to the formation of polyethylene wear debris and the release of toxic metal ions into the human body, limiting, as a consequence, the lifetime of implants. The aim of this research is a surface modification of CoCrMo alloys in order to improve their biocompatibility and to decrease the release of metal ions and polyethylene debris. Thermal treatment in molten salts was the process employed for the deposition of tantalum-enriched coating. Tantalum and its compounds are considered biocompatible materials with low ion release and high corrosion resistance. Three different CoCrMo alloys were processed as substrates. An adherent coating of about 1 {mu}m of thickness, with a multilayer structure consisting of two tantalum carbides and metallic tantalum was deposited. The substrates and modified layers were characterized by means of structural, chemical and morphological analysis. Moreover nanoindentation, scratch and tribological tests were carried out in order to evaluate the mechanical behavior of the substrates and coating. The hardness of the coated samples increases more than double than the untreated alloys meanwhile the presence of the coating reduced the wear volume and rate of about one order of magnitude. - Highlights: Black-Right-Pointing-Pointer Thermal treatment in molten salts deposits a Ta-based coating on Co-based alloys. Black-Right-Pointing-Pointer Coating is composed by one or two tantalum carbides and/or metallic tantalum. Black-Right-Pointing-Pointer The coating structure depends on thermal temperature and substrates carbon content. Black-Right-Pointing-Pointer Coating is able to

  3. X-ray residual stress measurement on weld metal of nickel based alloy

    International Nuclear Information System (INIS)

    Residual stress on the weld metal of nickel based alloy was evaluated through x-ray diffraction and metallurgical study of the microstructure. Weld metal specimens were prepared from Alloy182 (JIS DNiCrFe-3) and Alloy132 (JIS DNiCrFe-1J) deposited on a steel plate. X-ray diffraction results show a strong [100] preferred orientation nearly normal to the surface of the weld metal. Crystallographic consideration predicts that dominant 311 diffractions appear around 25.2 and 72.5 degrees of ψ angle. For each diffraction, the peak shift was measured at the ψ angle showing the maximum diffraction intensity, using the side-inclination method (ψ-goniometer method) with a Mn x-ray tube and a PSPC (position sensitive proportional counter). The residual stress was determined by the peak shifts according to the two tilt method. The x-ray stress constant, K, on Alloy182 was determined experimentally. The depth profile of the residual stress was measured on the ground specimens with and without laser peening. Tensile residual stress due to the grinding work is observed in the surface layer of the unpeened specimen; however it changes to compressive after laser peening. The overall behavior of the depth profile of laser peened material agrees well with that of Alloy600 base metal measured in the previous studies, where the compressive residual stress with several hundred MPa at the surface gradually decreases and reaches to around 0 MPa at the depth of about 1 mm. (author)

  4. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    International Nuclear Information System (INIS)

    Highlights: ► The corrosion behavior of magnesium for orthopedic applications is extremely poor. ► The solvent (DCM, THF and DMF) had a strong effect on the coatings performance. ► Mg bar alloy coated with PVAc/DCM layers provided an excellent bonding strength. ► Treated samples indicated significant damping for the degradation rate. ► Cytocompatibility on MC3T3 cells of the PVAc/DCM samples revealed a good behavior. - Abstract: The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc–solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  5. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    Energy Technology Data Exchange (ETDEWEB)

    Abdal-hay, Abdalla [Departmentt of Bionano System Engineering, College of Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Mechanical Design Engineering, Advanced wind power system research institute, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Dewidar, Montasser [Department of Materials and Mechanical Design, Faculty of Energy Engineering, South Valley University, Aswan (Egypt); Lim, Jae Kyoo, E-mail: jklim@jbnu.ac.kr [Department of Mechanical Design Engineering, Advanced wind power system research institute, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The corrosion behavior of magnesium for orthopedic applications is extremely poor. Black-Right-Pointing-Pointer The solvent (DCM, THF and DMF) had a strong effect on the coatings performance. Black-Right-Pointing-Pointer Mg bar alloy coated with PVAc/DCM layers provided an excellent bonding strength. Black-Right-Pointing-Pointer Treated samples indicated significant damping for the degradation rate. Black-Right-Pointing-Pointer Cytocompatibility on MC3T3 cells of the PVAc/DCM samples revealed a good behavior. - Abstract: The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might

  6. Enterogastroesophageal reflux during barium enema: Report of a case

    International Nuclear Information System (INIS)

    Enterogastric reflux during barium enema examination has been ascribed to various causes including incompetence of the ilepcecal valve, shunt, fistula, excessive barium etc. Recently we have encountered a case of complete enterogastroesphageal regurgitation during barium enema examination performed for the reduction of the ileocolic intuosusception in 6 months old baby. The regurgitation occurred only in the first of two barium enema examinations conducted at one month interval for recurring intussusception. The barium-saline solution used in the present study was not more than 350 ml in quantity. No organic or physical causes of such a complete regurgitation could be determined

  7. Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

    Science.gov (United States)

    Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2016-06-01

    Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

  8. Chemical extraction of refractory inclusions from iron- and nickel-base alloys

    International Nuclear Information System (INIS)

    Most iron- and nickel-base alloys contain certain refractory inclusions, which affect the physical properties of the alloy. Carbides are the predominant inclusion, but oxides, nitrides, sulfides, borides, and phosphides may also be present. A chemical extraction has been developed which effectively separates these inclusions from the matrix without the application of an external potential. The refractory inclusions are quantitatively extracted by chemical dissolution of the matrix at 250C with a solution 0.9 M in copper(II) potassium chloride and hydrochloric acid. The reagent also contains 0.1 M tartaric acid to avoid contamination of the insoluble inclusion with matrix hydrolysis products. The chemical extractant is identified as the Berzelius reagent. The solvent is a general reagent for the isolation of most refractory phases: carbides, nitrides, phosphides, sulfides, oxides, and certain intermetallic compounds. The reagent dissolves alloys which are predominantly aluminum, cobalt, copper, iron, nickel, or zinc. The separation requires up to 24 hours to dissolve the alloys' matrix

  9. Growth Stresses in Thermally Grown Oxides on Nickel-Based Single-Crystal Alloys

    Science.gov (United States)

    Rettberg, Luke H.; Laux, Britta; He, Ming Y.; Hovis, David; Heuer, Arthur H.; Pollock, Tresa M.

    2016-03-01

    Growth stresses that develop in α-Al2O3 scale that form during isothermal oxidation of three Ni-based single crystal alloys have been studied to elucidate their role in coating and substrate degradation at elevated temperatures. Piezospectroscopy measurements at room temperature indicate large room temperature compressive stresses in the oxides formed at 1255 K or 1366 K (982 °C or 1093 °C) on the alloys, ranging from a high of 4.8 GPa for René N4 at 1366 K (1093 °C) to a low of 3.8 GPa for René N5 at 1255 K (982 °C). Finite element modeling of each of these systems to account for differences in coefficients of thermal expansion of the oxide and substrate indicates growth strains in the range from 0.21 to 0.44 pct at the oxidation temperature, which is an order of magnitude higher than the growth strains measured in the oxides on intermetallic coatings that are typically applied to these superalloys. The magnitudes of the growth strains do not scale with the parabolic oxidation rate constants measured for the alloys. Significant spatial inhomogeneities in the growth stresses were observed, due to (i) the presence of dendritic segregation and (ii) large carbides in the material that locally disrupts the structure of the oxide scale. The implications of these observations for failure during cyclic oxidation, fatigue cycling, and alloy design are considered.

  10. Airfoil-based piezoelectric energy harvesting by exploiting the pseudoelastic hysteresis of shape memory alloy springs

    Science.gov (United States)

    de Sousa, Vagner Candido; De Marqui Junior, Carlos

    2015-12-01

    The modeling and analysis of an electromechanically coupled typical aeroelastic section with shape memory alloy springs for wind energy harvesting is addressed in this paper. An airfoil with two-degrees-of-freedom, namely pitch and plunge, is considered and piezoelectric coupling is added to the plunge degree-of-freedom. A load resistance is assumed in the electrical domain of the problem in order to estimate the electrical power output. Shape memory alloy coil springs are modeled in the pitch degree-of-freedom of the typical section. A nickel-titanium alloy that exhibits pseudoelasticity at room temperature is assumed. The constitutive model for the shape memory alloy is based on classical phenomenological models. The unsteady aerodynamic loads are obtained by Jones’ approximation to Wagner’s indicial function. The resulting nonlinear electroaeroelastic model is cast into a state-space representation and solved with a Runge-Kutta method. The effects of preload values of the shape memory springs and resistive power generation on the aeroelastic behavior of the wind energy harvester are investigated at the flutter boundary and in a post-flutter regime. The nonlinear kinetics of the austenite-to-martensite phase transformation changes the typical linear flutter behavior to stable limit-cycle oscillations over a range of airflow speeds. Such nonlinear aeroelastic behavior introduced by the hysteretic behavior of the SMA springs provides an important source of persistent electrical power.

  11. Stress corrosion cracking of Ni-base and Ti alloys under controlled potential

    International Nuclear Information System (INIS)

    Susceptibility to stress corrosion cracking (SCC) of alloy C-22 and Ti Gr-12, two candidate alloys for the inner-container of the multi-barrier nuclear waste package, was evaluated by using the slow-strain-rate (SSR) test technique in a deaerated acidic brine (pH ∼ 2.70) at 90 C. The strain rate used was 3.3 x 10-6 sec-1. Prior to being tested in the acidic brine, specimens of each alloy were pulled inside the test chamber in the dry condition at room temperature (RT). Then specimens were exposed to the test solution while being strained under different controlled electrochemical potentials. The magnitude of the controlled potential was selected based on the corrosion potential measured in the test solution prior to straining of the specimen. Results indicate that, for Ti Gr-12, the times to failure were significantly shorter compared to those for alloy C-22. Furthermore, Ti Gr-12 showed reduced ductility in terms of percent reduction in area and true fracture stress, as the controlled potential became more cathodic. Results also indicate that the time-to-failure and percent elongation reached the minimum values when Ti Gr-12 was tested under impressed potential of -1162 mV. Finally, metallographic examination was performed to evaluate the primary fracture, and the secondary cracking, if any, along the gage section of the broken tensile specimen

  12. Stress corrosion cracking mechanisms of Fe-based alloys in hydrogenated hot water

    International Nuclear Information System (INIS)

    It is generally accepted that carbon steel resists Stress Corrosion Cracking (SCC) in hot water provided the oxygen content is low enough; however, isolated cracking events have occurred, apparently in fully reducing conditions, and these may or may not be true SCC. There are also occasional reports of SCC of austenitic stainless steel in reducing conditions where cold work may play a critical role. SCC though originally seen in sensitized material at oxidizing potentials persists to low potentials and in cold-worked but unsensitized material. We suspect from the literature that alloying with Ni introduces a susceptibility to SCC in reducing hot water as well as in caustic solution. Our hypothesis is that Ni causes SCC, and Cr retards it; so stainless steel has just enough Cr to protect against SCC under most conditions. We are examining this using model Fe-based materials and environments designed to separate the effects of different parameters. Early results suggest that Fe-Ni alloys and austenitic SS both undergo de-alloying and SCC in reducing caustic solutions. It is hypothesised that if these alloys are indeed susceptible to dealloying (and hence to SCC) in this environment then we can reasonably project that their behaviour in reducing, hot pure water may be similar. This is pertinent to understanding recent failures in high temperature, high pressure aqueous systems. As a first step we have investigated the surface reactions that occur in caustic solutions and in hot water. (author)

  13. Creep Rupture Properties for Base and Weld Metals of Alloy 617

    International Nuclear Information System (INIS)

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

  14. De Haas-van Alphen effect study of electronic structures of niobium-based molybdenum alloys

    International Nuclear Information System (INIS)

    The electronic structures of dilute niobium-based molybdenum alloys have been studied by using the de Haas-van Alphen effect. The rate of increase of the Dingle temperature (ΔTsub(D)* on alloying is found to be fairly small compared with that of noble-metal alloys and to be anisotropic over the Fermi surfaces, that is, 3 K (at% Mo)-1 for ν oscillations arising from the ellipsoids, and 7 K (at% Mo)-1 for α and eta oscillations arising from the jungle gym. The change in frequency of the ν3456 oscillation is about 2/3 that predicted by the rigid band model. Applying the partial-wave analysis to these experimental facts, the following results are obtained. (i) T/e d wave phase shift dominates over s, p and f wave phase shifts in this alloy system and the anisotropy in ΔTsub(D)* results from the anisotropy in the amount of d component of the wavefunction over the Fermi surfaces. (ii) The non-rigid band-like behaviour of the ν3456 oscillation arises from the same origin as ΔTsub(D)*. (iii) The significantly small ΔTsub(D)* found in the present experiment is related to a small electron group velocity on the Fermi surfaces in niobium. (author)

  15. Effects in Mg-Zn-based alloys strengthened by quasicrystalline phase

    Science.gov (United States)

    Vlček, M.; Čížek, J.; Lukáč, F.; Melikhova, O.; Hruška, P.; Procházka, I.; Vlach, M.; Stulíková, I.; Smola, B.; Jäger, A.

    2016-01-01

    Magnesium Mg-based alloys are promising lightweight structural materials for automotive, aerospace and biomedical applications. Recently Mg-Zn-Y system attracted a great attention due to a stable icosahedral phase (I-phase) with quasicrystalline structure which is formed in these alloys. Positron lifetime spectroscopy and in situ synchrotron X-ray diffraction were used to study thermal stability of I-phase and precipitation effects in Mg-Zn-Y and Mg- Zn-Al alloys. All alloys containing quasicrystalline I-phase exhibit misfit defects characterized by positron lifetime of ∼ 300 ps. These defects are associated with the interfaces between I- phase particles and Mg matrix. The quasicrystalline I-phase particles were found to be stable up to temperatures as high as ∼ 370°C. The W-phase is more stable and melts at ∼ 420°C. Concentration of defects associated with I-phase decreases after annealing at temperatures above ∼ 300°C.

  16. A refined energy-based model for friction stir processing of AlZn-Mg alloy

    Directory of Open Access Journals (Sweden)

    P. K. Mandal

    2016-01-01

    Full Text Available Friction stir processing (FSP is a promising solid state surface modification technique. Also, considered as an innovative technique that the FSPwas employed to modify the surface layer of aluminium alloy. The FSP passes of only two passes were applied on aluminium alloy samples. A rotating tool with a pin and shoulder is inserted into a single piece of material and results in significant microstructural changes in the processed zone, due to intense plastic deformation. It has been proved to be an effective way to refine the microstructure of aluminium alloys, and thereby improve the mechanical properties. In procedural phenomenon there are different parameters adjustment have been worked out to refine microstructure and several properties characterised to TEM, SEM, FESEM and mechanical properties. In this study, a refined energy based model that estimates the energy generated due to friction and plastic deformation is presented with the help ofexperimental and theoretical results available in many literatures. The model is applied to 7xxx series of aluminium alloys.

  17. High Temperature Heat Capacity of Alloy D9 Using Drop Calorimetry Based Enthalpy Increment Measurements

    Science.gov (United States)

    Banerjee, Aritra; Raju, S.; Divakar, R.; Mohandas, E.

    2007-02-01

    Alloy D9 is a void-swelling resistant nuclear grade austenitic stainless steel (SS) based on AISI type 316-SS in which titanium constitutes an added predetermined alloying composition. In the present study, the high-temperature enthalpy values of alloy D9 with three different titanium-to-carbon mass percent ratios, namely Ti/C = 4, 6, and 8, have been measured using inverse drop calorimetry in the temperature range from 295 to 1323 K. It is found that within the level of experimental uncertainty, the enthalpy values are independent of the Ti-C mass ratio. The temperature dependence of the isobaric specific heat C P is obtained by a linear regression of the measured enthalpy data. The measured C P data for alloy D9 may be represented by the following best-fit expression: C_P(J \\cdot kg^{-1}\\cdot K^{-1})= 431 + 17.7 × 10^{-2}T + 8.72 × 10^{-5}/T^2. It is found that the measured enthalpy and specific heat values exhibit good agreement with reported data on 316 and other related austenitic stainless steels.

  18. Corrosion and Sliding Properties of the Nickel-Based Alloys for the Valve Seats Application

    International Nuclear Information System (INIS)

    This paper describes the experiments of the corrosion and the sliding tests of the nickel-based alloys for the gate valve seating materials used at high pressure and temperature. The general corrosion rates and IGC susceptibility are tested in pressurized water at 533 K and 575 k and in Strauss test solution. The sliding tests have been done in pressurized water at 293 k, 473 K and 573 k. The alloys containing above 10% chromium may have the anti-corrosion properties that could be applied to the valve seats for the power plants. The good sliding performance and the good pressure tightness are obtained when the disc specimens that have hardness 500 to 600 Hv combined with the seat specimens that have hardness 250 to 410 Hv containing about 40 percent of iron. The large size gate valves sliding tests have certified the test results. The anti-wear properties of the seat alloy and the anti-IGC susceptibility of the disc alloy could be improved by the addition of silicon and niobium, respectively

  19. High temperature oxidation and electrochemical investigations on nickel-base alloys

    International Nuclear Information System (INIS)

    This study examined high-temperature oxidation behavior of different Ni-base alloys. In addition, electrochemical characterization of the alloy's corrosion behavior was carried out, including comparison of the properties of native passive films grown at room temperature and high temperature oxide scales. PWA 1483 (single-crystalline Ni-base superalloy) and model alloys Ni-Cr-X (where X is either Co or Al) were oxidized at 800 and 900 C in air for different time periods. The superalloy showed the best oxidation behavior at both temperatures, which might be due to the fact that the oxidation growth function is subparabolic for the model alloys and parabolic for the superalloy at 800 C. At higher temperatures, changes in the kinetics are induced, as the oxides grow faster, thus only PWA 1483 growth follows the parabolic law. Different scales in a typical sandwich form were detected, with the inner layer comprised of mostly Cr2O3, the middle layer was mixture of different oxides and spinels, depending on the alloying elements, and the oxide at the interface oxygen/oxide was found to be NiO. The influence of sample preparation could also be shown, as rougher surfaces change the oxidation kinetics from parabolic and subparabolic for polished samples to linear. The influence of moisture on the oxidation behavior of the 2nd generation single crystal Ni-base superalloys (PWA 1484, PWA 1487, CMSX 4, Rene N5 and Rene N5+) was studied at 1000 C after 100 h oxidation period. It was found that the moisture increased the oxidation rate and mostly the transient oxides growth rate. The water vapor content in air also influenced the behavior of these alloys, as they showed a higher mass gain in air + 30% water vapor than in air + 10% water vapor. The alloys PWA 1484 and CMSX 4 showed respectively the worst and best behavior in all the studied atmospheres. The addition of reactive elements, such as Yttrium, Hafnium and Lanthanum is likely to enhance the oxidation behavior of PWA 1487

  20. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys

    Institute of Scientific and Technical Information of China (English)

    Bo Chen; Gang Xia; Xin-Ming Cao; Jue Wang; Bi-Yao Xu; Pu Huang; Yue Chen; Qing-Wu Jiang

    2013-01-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of 〈 1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of 〈1, 1 to 〈3 and 3 to 〈6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  1. Various transformation modes observed in two-phase γ + α2 TiAl-based alloys

    International Nuclear Information System (INIS)

    This paper deals with various transformation modes taking place in two-phase γ+α2 TiAl-based alloys. These transformation modes are: (1) decomposition of the α phase leading to the precipitation of the γ lamellae (α→α+γ), (2) ordering reaction of the α phase (α→α2), (3) massive transformation (α→γ), (4) formation of monolithic γ grains and (5) discontinuous coarsening. By analyzing their kinetics, three types of competitions were identified between these transformation modes: (1) vs. (2), (2) vs. (3) and (4) vs. (5). The occurrence of (2) or (3) and (4) or (5) in binary alloys is strongly dependent on the alloy composition. Therefore, by examining these two competitions in transformation modes, it is possible to evaluate the influence of small additions of ternary and quaternary elements on the response to heat treatments without a precise knowledge of the phase diagrammes of complex alloy systems. Another important finding of the present study is related to the formation of the γ phase from the α phase; this can occur through either lamellar precipitation (α → α2 → α2+γ, or α → α+γ → α2+γ) or massive reaction (α → γ). The mechanisms involved during these two transformations are investigated and some of the key issues are discussed in the present paper. (orig.)

  2. Strain engineered barium strontium titanate for tunable thin film resonators

    Energy Technology Data Exchange (ETDEWEB)

    Khassaf, H.; Khakpash, N. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Sun, F. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Sbrockey, N. M.; Tompa, G. S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Kalkur, T. S. [Department of Electrical and Computer Engineering, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States); Alpay, S. P., E-mail: p.alpay@ims.uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-05-19

    Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.

  3. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    Science.gov (United States)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  4. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... Commission found that the domestic interested party group response to its notice of institution (74 FR 31757... COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Notice of Commission determination to conduct a full five-year review concerning the antidumping duty order on...

  5. Impurities in barium titanate posistor ceramics

    Czech Academy of Sciences Publication Activity Database

    Korniyenko, S. M.; Bykov, I. P.; Glinchuk, M. J.; Laguta, V. V.; Belous, A. G.; Jastrabík, Lubomír

    2000-01-01

    Roč. 239, - (2000), s. 1209-1218. ISSN 0015-0193 Institutional research plan: CEZ:AV0Z1010914 Keywords : barium titanate phase transition * ESR * positive temperature coefficient of resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.547, year: 2000

  6. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... established a schedule for the conduct of this review (74 FR 62587, November 30, 2010). Subsequently, counsel... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION:...

  7. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  8. Influence of the pulsed plasma treatment on the corrosion resistance of the low-alloy steel plated by Ni-based alloy

    Science.gov (United States)

    Dzhumaev, P.; Yakushin, V.; Kalin, B.; Polsky, V.; Yurlova, M.

    2016-04-01

    This paper presents investigation results of the influence of high temperature pulsed plasma flows (HTPPF) treatment on the corrosion resistance of low-alloy steel 0.2C-Cr-Mn- Ni-Mo cladded by the rapidly quenched nickel-based alloy. A technique that allows obtaining a defect-free clad layer with a good adhesion to the substrate was developed. It is shown that the preliminary treatment of steel samples by nitrogen plasma flows significantly increases their corrosion resistance in the conditions of intergranular corrosion test in a water solution of sulfuric acid. A change of the corrosion mechanism of the clad layer from intergranular to uniform corrosion was observed as a result of sub-microcrystalline structure formation and homogeneous distribution of alloying elements in the plasma treated surface layer thus leading to the significant increase of the corrosion resistance.

  9. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  10. Metallurgical characterizations of Fe–Cr–Ni–Zr base alloys developed for geological disposal of radioactive hulls

    International Nuclear Information System (INIS)

    Highlights: ► Immobilization of Zr-rich radioactive metallic wastes via alloy melting route. ► First detail report on metallurgical characterizations of Fe–Cr–Ni–Zr alloys. ► Identification of suitable base alloy composition. - Abstract: Alloy melting route is currently being considered for radioactive hulls immobilization. Towards this, wide range of alloys, belonging to Zirconium–Iron binary and Zirconium–Stainless steel pseudo-binary systems have been prepared through vacuum arc melting route. Detail microstructural characterization and quantitative phase analyses of these alloys along with interaction study between Zirconium and Stainless steel coupons at elevated temperatures identify Zr(Fe,Cr)2, Zr(Fe,Cr), Zr2(Fe,Cr), Zr3(Fe,Ni), Zr3(Fe,Cr), Zr3(Fe,Cr,Ni), β-Zr and α-Zr as the most commonly occurring phases within the system for Zirconium rich bulk compositions. Nano-indentation studies found Zr(Fe,Cr)2 and Zr(Fe,Cr) as extremely hard, Zr3(Fe,Ni) as moderately ductile and β-Zr, Zr2(Fe,Cr) as most ductile ones among the phases present. Steam oxidation studies of the alloys, based on weight gain/loss procedure and microstructural characterization of the mixed oxide layers, suggest that each of the alloys responded to the corrosive environment differently. Fe2O3, NiFe2O4, NiO, monoclinic ZrO2 and tetragonal ZrO2 are found to be most common constituents of the oxide layers developed on the alloys. Integrating the microstructural, mechanical and corrosion properties, ZrFeCrNi3 (Zr: 84.00, Fe: 11.20, Cr: 3.20, Ni: 1.60, in wt.%) is identified as the acceptable base alloy for disposal of radioactive hulls.

  11. Microstructural evolutions and mechanical behaviour of the nickel based alloys 617 and 230 at high temperature

    International Nuclear Information System (INIS)

    High Temperature Reactors (HTR), is one of the innovative nuclear reactor designed to be inherently safer than previous generation and to produce minimal waste. The most critical metallic component in that type of reactor is the Intermediate Heat exchanger (IHX). The constraints imposed by the conception and the severe operational conditions (high temperature of 850 C to 950 C, lifetime of 20,000 h) have guided the IHX material selection toward two solid solution nickel base alloys, the Inconel 617 and the Haynes 230. Inconel 617 is the primary candidate alloy thanks to its good high temperature mechanical and corrosion properties and the large data base developed in previous programs. However, its high cobalt content has to be considered as an issue (nuclear activation). The more recent alloy Haynes 230, in which most of the cobalt has been replaced by tungsten, present characteristics similar to the 617 alloy. The objective of this thesis is to study the high temperature mechanical behaviour of both alloys in relation with their microstructural evolutions. The as received microstructural observations have revealed primary carbides (M6C). Most of this precipitates are evenly distributed in the materials. Few M23C6 secondary carbides are observed in both alloys in the as received state. Thermal ageing treatments at 850 C lead to an important M23C6 precipitation on slip lines and at grain boundaries. The size of this carbides increases and their number decreases with increasing ageing duration. The intragranular precipitation of secondary carbides at 950 C is more limited and the intergranular evolution more important than at 850 C. The microstructural observations and the hardness evolution of both alloys show that the main microstructural evolutions occur before 1,000 h at both studied temperatures. The mechanical properties of the Inconel 617 and the Haynes 230 have been studied using tensile, creep, fatigue and relaxation-fatigue tests. Particularly, the

  12. Highly aligned arrays of high aspect ratio barium titanate nanowires via hydrothermal synthesis

    International Nuclear Information System (INIS)

    We report on the development of a hydrothermal synthesis procedure that results in the growth of highly aligned arrays of high aspect ratio barium titanate nanowires. Using a multiple step, scalable hydrothermal reaction, a textured titanium dioxide film is deposited on titanium foil upon which highly aligned nanowires are grown via homoepitaxy and converted to barium titanate. Scanning electron microscope images clearly illustrate the effect the textured film has on the degree of orientation of the nanowires. The alignment of nanowires is quantified by calculating the Herman's Orientation Factor, which reveals a 58% improvement in orientation as compared to growth in the absence of the textured film. The ferroelectric properties of barium titanate combined with the development of this scalable growth procedure provide a powerful route towards increasing the efficiency and performance of nanowire-based devices in future real-world applications such as sensing and power harvesting

  13. Barium sulphate preparations for use in double contrast examination of the upper gastrointestinal tract

    International Nuclear Information System (INIS)

    Physical properties relevant to upper gastrointestinal radiology have been compared for five barium sulphate preparations and related to radiographic results. Evaluation of particles (size and stability) and whole suspension (dispersibility and fluidity) resulted in ranking of the preparations generally in accord with that based on radiological experience in double contrast examinations of the stomach. Experiments with extirpated pig stomach revealed a tendency for large particles in a low viscosity barium sulphate suspension to settle in mucosal grooves. This is believed to contribute to good radiographic definition of both the areae gastricae and small lesions. Particle size is therefore important and susceptibility to flocculation, a possible cause of random change in size during use, was assessed by measuring particle electrophoretic mobility under varying conditions; quantitative differences in suspension flow and dispersibility were also demonstrated. Fluidity and dispersibility together with rapid sedimentation of suitably sized particles resistant to flocculation underlie the successful use of low viscosity high density barium sulphate suspensions. (U.K.)

  14. Barium and strontium sulfate solid solution formation in relation to North Sea scaling problems

    International Nuclear Information System (INIS)

    This paper presents the results of laboratory experiments carried out to investigate barium sulphate and strontium sulphate solid solution formation in multi-pressure tapped cores. Two brines, one barium and strontium rich and the other sulphate rich, were mixed in a core plug. Pressure differentials were measured and the changing permeability distribution along the length of the core calculated. The morphology and chemical analysis of scaling crystals are presented based on Scanning electron Microsocpy (SEM) and Energy Dispersive X-ray Analysis (EDAX). The results show the large extent of permeability damage caused by (Ba, SR) SO/sub 4/ solid solution depositing on the rock pore surface. The rock permeability decline and morphology and size of the scaling crystals indicate the influence of the supersaturations of BaSO/sub 4/ and SrSO/sub 4/ as well as the concentration ratio of barium ions to strontium ions

  15. AB INITIO Modeling of Thermomechanical Properties of Mo-Based Alloys for Fossil Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Wai-Yim

    2013-12-31

    In this final scientific/technical report covering the period of 3.5 years started on July 1, 2011, we report the accomplishments on the study of thermo-mechanical properties of Mo-based intermetallic compounds under NETL support. These include computational method development, physical properties investigation of Mo-based compounds and alloys. The main focus is on the mechanical and thermo mechanical properties at high temperature since these are the most crucial properties for their potential applications. In particular, recent development of applying ab initio molecular dynamic (AIMD) simulations to the T1 (Mo{sub 5}Si{sub 3}) and T2 (Mo{sub 5}SiB{sub 2}) phases are highlighted for alloy design in further improving their properties.

  16. A set of microstructure-based constitutive equations in hot forming of a titanium alloy

    Institute of Scientific and Technical Information of China (English)

    Xiaoli Li; Miaoquan Li

    2006-01-01

    A physical model of microstructure evolution including dislocation density rate and grain growth rate was established based on the deformation mechanism for the hot forming of a class of two-phase titanium alloys. Further, a set of mechanism-based constitutive equations were proposed, in which the microstructure variables such as grain size and dislocation density were taken as internal state variables for characterizing the current material state. In the set of constitutive equations, the contributions of different mechanisms and individual phase to the deformation behavior were analyzed. The present equations have been applied to describe a correlation of the flow stress with the microstructure evolution of the TC6 alloy in hot forming.

  17. Grain refinement effects of Al based alloys with low titanium content produced by electrolysis

    Institute of Scientific and Technical Information of China (English)

    刘志勇; 王明星; 翁永刚; 宋天福; 谢敬佩; 霍裕平

    2002-01-01

    A series of Al based alloys with low titanium contents (mass fraction) from 0.178% to 0.526% were directly produced in ordinary industrial electrolyzer. The electrolyzing results show that producing Al based alloys with titanium contents of less than 0.30% without great loss of electrolysis efficiency is possible. The quantitative analysis shows that this method has a great refining effect on transiting the coarse columnar grains in pure Al to equiaxed grains. The grain sizes decrease with the increase of titanium content and tend to a low limit at about 130μm. During the solidification, the non-equilibrium distribution of titanium leads to a great growth-restricting effect and a constitutional under-cooling zone in front of the growing liquid /solid interface.

  18. Correlation between liquid structure and glass forming ability in glassy Ag-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.

  19. Hardness analysis and morphological characterization of copper-zinc alloys produced in pyrophosphate-based electrolytes

    Directory of Open Access Journals (Sweden)

    Lilian Ferreira de Senna

    2005-09-01

    Full Text Available In this work, copper-zinc alloy coatings on mild steel substrates were obtained in nontoxic pyrophosphate-based electrolytes, at room temperature and under continuous current. The effects of bath composition and current density on the hardness of the coatings, as well as on their morphologies, were evaluated. The results showed that the electrolyte composition, and the use of stress relieving additives strongly influence the hardness of the coatings, while the current density directly affect their morphology. Hence, for a current density of 116 A/m², copper-zinc alloy deposits with no pores or cracks were produced in a pyrophosphate-based electrolyte, especially when allyl alcohol was added to the solution.

  20. NASA-UVa light aerospace alloy and structures technology program supplement: Aluminum-based materials for high speed aircraft

    Science.gov (United States)

    Starke, E. A., Jr. (Editor)

    1995-01-01

    This report on the NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from July 1, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) Ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) Powder metallurgy 2XXX alloys, (3) Rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) Discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.