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Sample records for barium base alloys

  1. Strengthening mechanism of steels treated by barium-bearing alloys

    Institute of Scientific and Technical Information of China (English)

    Zhouhua Jiang; Yang Liu

    2008-01-01

    The deoxidation, desulfurization, dephosphorization, microstructure, and mechanical properties of steels treated by barium-bearing alloys were investigated in laboratory and by industrial tests. The results show that barium takes part in the deoxidation reaction at the beginning of the experiments, generating oxide and sulfide compound inclusions, which easily float up from the molten steel, leading to the rapid reduction of total oxygen content to a very low level. The desulfurization and dephosphorization capabilities of calcium-bearing alloys increase with the addition of barium. The results of OM and SEM observations and mechanical property tests show that the structure of the steel treated by barium-bearing alloys is refined remarkably, the iamellar thickness of pearlitic structure decreases, and the pearlitic morphology shows clustering distribution. Less barium exists in steel substrate and the enrichment of barium-bearing precipitated phase mostly occurs in grain boundary and phase boundary, which can prevent the movement of grain boundary and dislocation during the heat treatment and the deformation processes. Therefore, the strength and toughness of barium-treated steels are improved by the effect of grain-boundary strengthening and nail-prick dislocation.

  2. Deoxidation Behavior of Alloys Bearing Barium in Molten Steel

    Institute of Scientific and Technical Information of China (English)

    LI Yang; JIANG Zhou-hua; JIANG Mao-fa; WANG Jun-wen; GU Wen-bing

    2003-01-01

    The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0.002 0 % to 0.002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.

  3. Barium phosphate conversion coating on die-cast AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Poor corrosion resistance limits the application of magnesium alloys.Conversion coating is widely used to protect magnesium alloys because of easy operation and low cost.A novel conversion coating on die.cast AZ91D magnesium alloy containing barium salts was studied.The optimum concentrations of Ba(NO3)2,Mn(NO3)2 and NH4H2PO4 are 25 g/L,15 mL/L and 20 g/L,respectively,based on orthogonal test resulm.The treating time,solution temperature and PH value are settled to be 5-30 min,50-70℃and 2.35-3.0.respectively.The corrosion resistance of barium conversion coating is better than that of manganese-based phosphate conversion coating by immersion test.The coating is composed of Ba,P, O,Mg,Zn,Mn and Al by EDX analysis.

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

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus;

    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 as effective for Fe. Power-law kinetic investigation revealed that, compared to the commercial Fe-based NH3 catalyst, the Ba–Co/C samples showed a lower inhibition by NH3 and were more active under ordinary ammonia synthesis conditions....

  5. 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.

  6. 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

  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.

  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.

  11. Barium Sulfate

    Science.gov (United States)

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

  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. Effects of barium on the nonlinear electrical characteristics and dielectric properties of SnO2-based varistors

    Institute of Scientific and Technical Information of China (English)

    Wang Chun-Ming; Wang Jin-Feng; Wang Chun-Lei; Chen Hong-Cun; Su Wen-Bin; Zang Guo-Zhong; Qi Peng; Zhao Ming-Lei; Ming Bao-Quan

    2004-01-01

    The effects of barium on electrical and dielectric properties of the SnO2·Co2Oa.Ta2O5 varistor system sintered at 1250℃ for 60min were investigated. It is found that barium significantly improves the nonlinear properties. The breakdown electrical field increases from 378.0 to 2834.5V/mm, relative dielectric constant (at 1kHz) falls from 1206 to 161 and the resistivity (at 1kHz) rises from 60.3 to 1146.5kΩ·cm with an increase of BaCO3 concentration from 0mol%to 1.00mol%. The sample with 1.00mol% barium has the best nonlinear electrical property and the highest nonlinear coefficient (α=29.2). A modified defect barrier model is introduced to illustrate the grain-boundary barrier formation of barium-doped SnO2-based varistors.

  14. Use of Different Barium Salts to Inhibit the Thaumasite Form of Sulfate Attack in Cement-based Materials

    Institute of Scientific and Technical Information of China (English)

    SU Ying; WEI Xiaochao; HUANG Jian; WANG Yingbin; HE Xingyang; WANG Xiongjue; MA Baoguo

    2016-01-01

    We investigated the effects of different barium compounds on the thaumasite form of sulphate attack (TSA) resistance of cement-based materials when they were used as admixtures in mortars. Moreover, we analyzed the inhibition mechanisms within different types of barium salts, namely BaCO3 and Ba(OH)2, on the thaumasite formation. The control cement mortar and mortars with barium salts to cement and limestone weight ratios of 0.5%, 1.0%, and 1.5% were immersed in 5% (by weight) MgSO4 solution at 5℃ to mimic TSA. Appearance, mass, and compressive strength of the mortar samples were monitored and measured to assess the general degradation extent of these samples. The products of sulphate attack were further analyzed by XRD, FTIR, and SEM, respectively. Experimental results show that different degradation extent is evident in all mortars cured in MgSO4 solution. However, barium salts can greatly inhibit such degradation. Barium in hydroxide form has better effectiveness in protection against TSA than carbonate form, which may be due to their solubility difference in alkaline cement pore solution, and the presence of these barium compounds can reduce the degree of TSA by comparison with the almost completely decomposed control samples.

  15. 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)

  16. 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...

  17. 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.)

  18. 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...

  19. 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.

  20. 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.

  1. 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.)

  2. 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...

  3. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. 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)

  6. 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.

  7. 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

  8. 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

  9. Acid-base buffer effect of fulvic acid and barium fulvate from weathered coal

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-feng; LI Xi-feng

    2009-01-01

    The acid-base buffer characteristics of fulvic acid (FA) and barium fulvate (BaFA) were analyzed. Each share of the sample or model agents (phthalic acid and salicylic acid) were separately mixed into a series of shares of dilute solutions of HCI or NaOH with a series of concentration. The original pH values of the solutions were arranged from 2 to 13. Final balanced pH of each share was measured. The pH changes show that FA and BaFA possess buffer ability, whereas the model agents do not. The tendency of balanced pH values was 5.4 for FA and 7.4 for BaFA, whereas the original pH was 4.0-8.5; balanced pH changed little. At room temperature, the maximum buffer capacities were as follows:18.11 mmol hydroxyl per gram FA, 11.25 mmol hydroxyl per gram BaFA, 1.19 mmol proton per gram FA, and 1.45 mmol proton per gram BaFA. Mathematics analysis shows that logarithm of buffer capacities of FA and BaFA is linearly dependent on original pH. Compared with BaFA and model agents, it is concluded that FA buffer capacity against hydroxyl relies not only on its acidic groups, BaFA buffer capacity against hydroxyl does not rely on its acidic groups, and FA buffer capacity against proton is not related with its carboxyl and phenolic hydroxyl group. The pH values of FA-water solutions with different concentrations from 1 to 10 grams per liter were measured. Their pH values were slightly affected by its concentration. Thus, FA possesses a much stronger buffer ability against water dilution than common buffer agent. All the pH values of FA water solutions were very nearby 5.4,just the same as the balanced pH tendency for adding FA.

  10. EDTA-type Polymer Based on Diazacrown Ether as the Solubilizer of Barium Sulfate to Water

    Institute of Scientific and Technical Information of China (English)

    Bo ZHOU; Jian Zhang LI; Chun Hong HE; Sheng Ying QIN

    2005-01-01

    The EDTA dianhydride reacted with diazacrown ethers to obtain the water-soluble EDTA-diazacrown ether polymers 1~3. The effects of crown ether ring in the polymer chains including its cavity size on the solubilization of barium sulfate to water were investigated by comparison with the crown ring-free analogue 4. The result shows that the polymer 2 is the efficient solubilizer of BaSO4 and the highest solubilization efficiency of the BaSO4 to water is up to 72.5%.

  11. Fabrication of flexible magnetic papers based on bacterial cellulose and barium hexaferrite with improved mechanical properties

    Science.gov (United States)

    Lim, Guh-Hwan; Lee, Jooyoung; Kwon, Nayoung; Bok, Shingyu; Sim, Hwansu; Moon, Kyoung-Seok; Lee, Sang-Eui; Lim, Byungkwon

    2016-09-01

    We report on a simple approach to fabricate mechanically robust magnetic cellulose papers containing M-type barium hexaferrite (BaFe12O19) nanoplates. BaFe12O19 nanoplates were synthesized by a hydrothermal method and then chemically functionalized by using a silane coupling agent. The magnetic cellulose papers prepared with the silane-treated BaFe12O19 nanoplates exhibited improved mechanical properties with tensile strength of 58.5 MPa and Young's modulus of 2.95 GPa.

  12. 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...

  13. 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)

  14. 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

  15. 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.

  16. Ductile Fe-based amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Kyu; Lee, Kwang-Bok [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Jae-Chul, E-mail: jclee001@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer Fe-based amorphous alloy with a strength and fracture strain of 4.7 GPa and 8.0% was synthesized. Black-Right-Pointing-Pointer Addition of a minute amount of V promoted the phase separation of the constituent elements. Black-Right-Pointing-Pointer Phase separation lowered alloys' packing density and alleviated the degree of strain localization. - Abstract: Experiments demonstrated that the addition of a minute amount of V to Fe{sub 52}Co{sub (20-x)}B{sub 20}Si{sub 4}Nb{sub 4}V{sub x} amorphous alloy induces atomic-scale phase separation, which dramatically enhances the plasticity. Especially, Fe{sub 52}Co{sub 17.5}B{sub 20}Si{sub 4}Nb{sub 4}V{sub 2.5} amorphous alloy exhibited a strength of 4.7 GPa and a fracture strain of 8.0%, which is the largest strain reported for Fe-based amorphous alloys. In this study, the structural origin of the enhanced plasticity is explored by examining the role played by the phase separating element on the packing density and strain localization.

  17. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Mohammad Mujahid Ali; Rafiuddin,, E-mail: rafi_amu@rediffmail.com

    2013-10-15

    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.

  19. 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)

  20. 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.

  1. 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.

  2. Fabric cutting application of FeAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Sklad, S.P. [Univ. of Virginia, Charlottesville, VA (United States); Deevi, S.C. [Philip Morris U.S.A., Richmond, VA (United States); Shih, H.R. [Jackson State Univ., MS (United States)

    1998-11-01

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60), and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel.

  3. 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.

  4. 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.

  5. 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

  6. New Developments of Ti-Based Alloys for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Yuhua Li

    2014-03-01

    Full Text Available Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.

  7. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    Energy Technology Data Exchange (ETDEWEB)

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  8. 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.

  9. 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.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. Non-alloyed Ni3Al based alloys – preparation and evaluation of mechanical properties

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2013-07-01

    Full Text Available The paper reports on the fabrication and mechanical properties of Ni3Al based alloy, which represents the most frequently used basic composition of nickel based intermetallic alloys for high temperature applications. The structure of the alloy was controlled through directional solidification. The samples had a multi-phase microstructure. The directionally solidified specimens were subjected to tensile tests with concurrent measurement of acoustic emission (AE. The specimens exhibited considerable room temperature ductility before fracture. During tensile testing an intensive AE was observed.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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 ...

  20. 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)

  1. 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.

  2. Tantalum modified ferritic iron base alloys

    Science.gov (United States)

    Oldrieve, R. E.; Blankenship, C. P. (Inventor)

    1977-01-01

    Strong ferritic alloys of the Fe-CR-Al type containing 0.4% to 2% tantalum were developed. These alloys have improved fabricability without sacrificing high temperature strength and oxidation resistance in the 800 C (1475 F) to 1040 C (1900 F) range.

  3. 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.

  4. 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.

  5. Fabric cutting application of FeAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Sklad, S.P. [University of Virginia, Charlottesville, VA 22905 (United States); Deevi, S.C. [Research, Development, and Engineering Center, Philip Morris USA, Richmond, VA 23234 (United States); Shih, H.-R. [Jackson State University, 1400 J.R. Lynch Street, Jackson, MS 39217 (United States)

    1998-12-31

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60) and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel. (orig.) 18 refs.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Broadly tunable, beta-barium-borate-based, pulsed optical parametric oscillators and their potential applications in medicine

    Science.gov (United States)

    Sobey, Mark S.; Clark, Jim; Johnson, Bertram C.

    1995-05-01

    With the recent availability of Beta Barium Borate (BBO) crystals in useful sizes at acceptable market prices, the promise of Optical Parametric Oscillators (OPOs) becoming practical tunable systems is finally being realized. Wavelength coverage from such systems extends from 420 nm to over 2400 nm when pumped in the UV. For medical applications their usage will be limited in the near term to low repetition rates (tattoo removal or treating vascular lesions. For such high energy devices peak powers necessitate the use of articulating arms for beam delivery. For high repetition rate systems, energy outputs will be in the range of 100 to 500 (mu) J at kHz frequencies (up to 1 W average power). Peak powers are low enough that fiber optic delivery is possible. These systems may find selective absorption applications in ophthalmology.

  13. Electrochemical properties of TiV-based hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    朱云峰; 李锐; 高明霞; 刘永锋; 潘洪革; 王启东

    2003-01-01

    The electrochemical properties of the super-stoichiometric TiV-based hydrogen storage electrode alloys(Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16Ni0.2)x(x=2, 3, 4, 5, 6) were studied. It is found by XRD analysis that all the al-loys mainly consist of a C14 Laves phase with hexagonal structure and a V-based solid solution phase with BCCstructure. The lattice parameters and the unit cell volumes of the two phases decrease with increasing x. The cyclelife, the linear polarization, the anode polarization and the electrochemical impedance spectra of the alloy electrodeswere investigated systematically. The overall electrochemical properties of the alloy electrode are found improvedgreatly as the result of super-stoichiometry and get to the best when x= 5.

  14. 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.

  15. Incorporation of Refractory Metals into Niobium Base Alloys

    OpenAIRE

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

    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.

  16. 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.

  17. Laser cladding of Ni-based alloy on stainless steel

    Institute of Scientific and Technical Information of China (English)

    XUE Chun-fang; TIAN Xin-li; TAN Yong-sheng; WU Zhi-yuan

    2004-01-01

    The coatings on a stainless steel substrate were conducted by laser cladding of Ni-based alloy, using a 5 kW continuous wave CO2 flow transverse laser. SEM, EDX and X-ray diffraction were used to analyze the microstructure and constituent phases of the obtained coatings by laser cladding with direct injection of the powder into the melt pool. Solidification planar, cellular and dendrite structures were observed in Ni-based alloy coating. There exists an optimum metallurgical bond between Ni-based laser cladding layer and the base material. The high hardness of the Ni-based alloy coating is attributed to the presence of M7C3-type carbides (essentially chromium-riched carbide) dispersed in the γ(Ni,Fe) phase matrix.

  18. 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).

  19. 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.

  20. 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.

  1. 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...

  2. Recrystallization characteristics of oxide dispersion strengthened nickel-base alloys

    Science.gov (United States)

    Hotzler, R. K.; Glasgow, T. K.

    1980-01-01

    Electron microscopy was employed to study the process of recrystallization in two oxide dispersion strengthened (ODS) mechanically alloyed nickel-base alloys, MA 754 and MA 6000E. MA 754 contained both fine, uniformly dispersed particles and coarser oxides aligned along the working direction. Hot rolled MA 754 had a grain size of 0.5 microns and high dislocation densities. After partial primary recrystallization, the fine grains transformed to large elongated grains via secondary (or abnormal) grain growth. Extruded and rolled MA 6000E contained equiaxed grains of 0.2 micron diameter. Primary recrystallization occurring during working eliminated virtually all dislocations. Conversion from fine to coarse grains was triggered by gamma prime dissolution; this was also a process of secondary or abnormal grain growth. Comparisons were made to conventional and oxide dispersion strengthened nickel-base alloys.

  3. 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.

  4. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  5. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Wilkening, D. [Columbia Falls Aluminum Co., 2000 Aluminum Dr., Columbia Falls, MT 59912 (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., P.O. Box 1071, Anaconda, MT 59711 (United States)

    1998-12-31

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{sup TM} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast. (orig.) 18 refs.

  6. Weldability and Microstructure of Nickel-Silicon Based Alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Qing-cai; LIU Yi; YANG Jian; J.W.Newkirk; ZHANG Shan-hong

    2006-01-01

    The NiSix based alloy typically has poor weldability due to its lower ductility. A limited amount of work has been performed on the weldability of NiSix based alloys. Therefore, the effect of heat treatment and welding parameters on weldability of the alloys, and the relationship between the weldability and microstructure were studied. The results show that the as-cast Ni-Si-Nb-B alloy (Ni 76.5%, Si 20%, Nb 3%, and B 0.5%) could be successfully welded after preheating at 600 ℃. The welding procedure should be performed on the alloys before any heat treatment and a preheating at 600 ℃ should be used. The fusion zone is harder than the matrix due to a large amount of γ phase and a finer microstructure. The cracks are predominantly intergranular in heat affected zone and associated with the needle-like γ phase. The heat treatment before welding increases the tendency of cracking in the fusion zone.

  7. Microfluidic platforms for gallium-based liquid metal alloy

    Science.gov (United States)

    Kim, Daeyoung

    As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non

  8. On Barium Oxide Solubility in Barium-Containing Chloride Melts

    Science.gov (United States)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V.

    2016-08-01

    Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl2-NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl2-MCl systems.

  9. [Dimensional changes of silver and gallium-based alloy].

    Science.gov (United States)

    Ballester, R Y; Markarian, R A; Loguercio, A D

    2001-01-01

    Gallium-based dental alloys were created with the aim of solving the problem of toxicity of mercury. The material shows mechanical properties similar to those of dental amalgam, but researches point out two unfavorable characteristics: great corrosion and excessive post-setting expansion, and the latter is capable of cracking dental structures. The aim of this study was to evaluate, during 7 days, the in vitro dimensional alteration of a gallium dental alloy (Galloy, SDI, Australia), in comparison with a dental amalgam containing zinc (F400, SDI, Australia), as a function of the contact with saline solution (0.9% NaCl) during the setting period. The storage experimental conditions were: storage in dry environment, immersion in saline solution and contamination during condensation. Additionally, the effects of contamination during the trituration of dental amalgam and the effects of protecting the surface of the gallium alloy with a fluid resin were studied. Specimens were stored at 37 degrees C +/- 1 degree C, and measuring was carried out, sequentially, every 24 h during 7 days. When the gallium alloy was either contaminated or immersed, an expansion significantly greater than that observed in the other experimental conditions was noticed after 7 days. The application of a fluid resin to protect the surface of the cylinders was able to avoid the increase in expansion caused by superficial moisture. The amalgam alloy did not show significant dimensional alterations, except when it was contaminated during trituration.

  10. 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.

  11. 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.

  12. Diffusion Bonding between TiAl Based Alloys and Steels

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The joint of 40Cr steel and TiAl based alloy has been studied by means of a high frequency induction diffusion welder. The experimental results show that, the higher the temperature and pressure, the higher the strength of the joints. The optimum parameters are: T=1123~1323 K,t=10~30 min, P=5~20 MPa.

  13. 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.

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

    DEFF Research Database (Denmark)

    Achiam, M.P.; Chabanova, E.; Logager, V.B.;

    2008-01-01

    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 ... 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%) polyps

  15. 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.

  16. 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

  17. 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.

  18. 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...

  19. Barium titanate particle model inquiry through effective permittivity measurements and boundary integral equation method based simulations of the BaTiO{sub 3}-epoxy resin composite material

    Energy Technology Data Exchange (ETDEWEB)

    Orlowska, S [Ecole Centrale de Lyon, Centre de Genie Electrique de Lyon, CNRS UMR 5005, 69134 Ecully (France); Beroual, A [Ecole Centrale de Lyon, Centre de Genie Electrique de Lyon, CNRS UMR 5005, 69134 Ecully (France); Fleszynski, J [Institute of Fundamental Electrotechnics and Electrotechnology, University of Technology of Wroclaw, Wroclaw (Poland)

    2002-10-21

    The heterogeneous mixture properties depend on its constituents' characteristics. We examine the effective permittivity of a two-phase composite material made of epoxy resin host matrix and barium titanate (BaTiO{sub 3}) filler for different volume fractions in the matrix. The task we undertake consists in finding a model of BaTiO{sub 3} particles through the computer simulations executed in PHI3D-electric field calculating package, based on the resolution of the Laplace equation using boundary integral equation method. With this aim in view we compare the measured results of the effective permittivity of the BaTiO{sub 3}-epoxy resin composite samples with the simulation results for different BaTiO{sub 3} particle geometric models and for the same experimental conditions, with regard to the given volume fraction of the powder in the matrix. The experimental results are obtained through the measurements with an impedance meter in the range of frequencies from 50 Hz to 1 MHz.

  20. 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.

  1. 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.

  2. 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.

  3. Replacement of Cobalt base alloys hardfacing by NOREM alloy; EDF experience and development, some metallurgical considerations. Valves application (CLAMA, RAMA)

    Energy Technology Data Exchange (ETDEWEB)

    Carnus, M. [EDF DPN UTO Direction Expertise Technique, Noisy le Grand (France); Confort, X. [VELAN SAS, Lyon (France)

    2011-07-01

    Cobalt base alloys, such as Stellite 6 and 21, are used extensively in applications where superior resistance to wear and corrosion are required. However the use of Cobalt alloys hardfacing materials, especially on valves, is a major contributor to the level of radioactive contamination of nuclear facilities. NOREM alloys, an iron base and cobalt free materials, have been developed through an Electric Power Research Institute (EPRI) long running program during the eighties as an alternative of Stellite. This alloy has relatively good weldability properties, it was developed initially for repairing Stellite hardfacing (deposit over existing hardfacing alloys). This alloy has good corrosion resistance properties associated with elevated hardness (HRC 36-42). Technological properties (such as galling resistance, wear resistance) have been evaluated through different testing programs led by EPRI, AECL(Atomic Energy of Canada Limited), Valves manufacturers, EDF and others during the nineties. More recently EDF (for replacement of globe valves) has carried out testing program focused on weld deposit chemistry and mechanical properties. NOREM is a candidate for replacement of stellite hardfacing on valves. However this alloy is not so versatile as stellite alloys regarding technological properties (such as wear resistance) at elevated temperature and under high contact pressure. As a consequence some limits have to be considered for application on valves operating at elevated temperature and under high contact pressure (> 20 Mpa). Examples of application on valves, from VELAN manufacturer, for EDF PWR equipment are given. The industrial feedback from installed equipment (CLAMA, RAMA) since 2006 on EDF PWR has been good

  4. Nitriding behavior of Ni and Ni-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonovic, Matej

    2015-01-15

    Gaseous nitriding is a prominent thermochemical surface treatment process which can improve various properties of metallic materials such as mechanical, tribological and/or corrosion properties. This process is predominantly performed by applying NH{sub 3}+H{sub 2} containing gas atmospheres serving as the nitrogen donating medium at temperatures between 673 K and 873 K (400 C and 600 C). NH{sub 3} decomposes at the surface of the metallic specimen and nitrogen diffuses into the surface adjacent region of the specimen whereas hydrogen remains in the gas atmosphere. One of the most important parameters characterizing a gaseous nitriding process is the so-called nitriding potential (r{sub N}) which determines the chemical potential of nitrogen provided by the gas phase. The nitriding potential is defined as r{sub N} = p{sub NH{sub 3}}/p{sub H{sub 2}{sup 3/2}} where p{sub NH{sub 3}} and p{sub H{sub 2}} are the partial pressures of the NH{sub 3} and H{sub 2} in the nitriding atmosphere. In contrast with nitriding of α-Fe where the nitriding potential is usually in the range between 0.01 and 1 atm{sup -1/2}, nitriding of Ni and Ni-based alloys requires employing nitriding potentials higher than 100 atm{sup -1/2} and even up to ∞ (nitriding in pure NH{sub 3} atmosphere). This behavior is compatible with decreased thermodynamic stability of the 3d-metal nitrides with increasing atomic number. Depending on the nitriding conditions (temperature, nitriding potential and treatment time), different phases are formed at the surface of the Ni-based alloys. By applying very high nitriding potential, formation of hexagonal Ni{sub 3}N at the surface of the specimen (known as external nitriding) leads to the development of a compound layer, which may improve tribological properties. Underneath the Ni{sub 3}N compound layer, two possibilities exist: (i) alloying element precipitation within the nitrided zone (known as internal nitriding) and/or (ii) development of metastable and

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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...

  10. 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.

  11. 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?

  12. Synthesis and characterization of nanostructured palladium-based alloy electrocatalysts

    Science.gov (United States)

    Sarkar, Arindam

    Low temperature fuel cells like proton exchange membrane fuel cells (PEMFC) are expected to play a crucial role in the future hydrogen economy, especially for transportation applications. These electrochemical devices offer significantly higher efficiency compared to conventional heat engines. However, use of exotic and expensive platinum as the electrocatalyst poses serious problems for commercial viability. In this regard, there is an urgent need to develop low-platinum or non-platinum electrocatalysts with electrocatalytic activity for the oxygen reduction reaction (ORR) superior or comparable to that of platinum. This dissertation first investigates non-platinum, palladium-based alloy electrocatalysts for ORR. Particularly, Pd-M (M = Mo and W) alloys are synthesized by a novel thermal decomposition of organo-metallic precursors. The carbon-supported Pd-M (M = Mo, W) electrocatalyts are then heat treated up to 900°C in H2 atmosphere and investigated for their phase behavior. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo or W significantly enhances the catalytic activity for ORR as well as the stability (durability) of the electrocatalysts. Additionally, both the alloy systems exhibit high tolerance to methanol, which is particularly advantageous for direct methanol fuel cells (DMFC). The dissertation then focuses on one-pot synthesis of carbon-supported multi-metallic Pt-Pd-Co nanoalloys by a rapid microwave-assisted solvothermal (MW-ST) method. The multi-metallic alloy compositions synthesized by the MW-ST method show much higher catalytic activity for ORR compared to their counterparts synthesized by the conventional borohydride reduction method. Additionally, a series of Pt encapsulated Pd-Co nanoparticle electrocatalysts are synthesized by the MW-ST method and characterized to understand their phase behavior, surface composition, and electrocatalytic activity for ORR. Finally, the dissertation

  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

    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.

  14. 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.

  15. Perspectives on radiation effects in nickel-base alloys for applications in advanced reactors

    Science.gov (United States)

    Rowcliffe, A. F.; Mansur, L. K.; Hoelzer, D. T.; Nanstad, R. K.

    2009-07-01

    Because of their superior high temperature strength and corrosion properties, a set of Ni-base alloys has been proposed for various in-core applications in Gen IV reactor systems. However, irradiation-performance data for these alloys is either limited or non-existent. A review is presented of the irradiation-performance of a group of Ni-base alloys based upon data from fast breeder reactor programs conducted in the 1975-1985 timeframe with emphasis on the mechanisms involved in the loss of high temperature ductility and the breakdown in swelling resistance with increasing neutron dose. The implications of these data for the performance of the Gen IV Ni-base alloys are discussed and possible pathways to mitigate the effects of irradiation on alloy performance are outlined. A radical approach to designing radiation damage-resistant Ni alloys based upon recent advances in mechanical alloying is also described.

  16. 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

  17. Corrosion-resistant nickel-base alloys for gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J.W.; Hulsizer, W.R.

    1976-08-01

    Laboratory corrosion screening procedures used during the past ten years in developing nickel-base superalloys for gas turbine applications are described. Hot salt corrosion tests have included crucible and salt shower exposures. Reproducible techniques were established and alloy composition effects defined, leading to development of M313, IN-587, a IN-792. Correlations have been made with corrosion results in burner rigs, and engine experience confirming anticipated behavior is now becoming available. During this work a number of limitations of these accelerated laboratory tests were uncovered; these are discussed. Finally, brief descriptions of the states of development of alloy MA 755E (an oxide dispersion-strengthened superalloy) and IN-939 (a cast 23 percent chromium superalloy) are outlined as examples of advanced corrosion resistant, high strength materials of the future.

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. Structural characteristics of Ni3Al based alloys depending on the preparation conditions

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2015-10-01

    Full Text Available The paper presents an evaluation of the influence of the composition of alloys based on Ni3Al on their mechanical characteristics. The structure of the alloy was controlled through directional solidification. The achieved values of mechanical characteristics are in good agreement with the material structure. The alloys with sub-stoichiometric contents of aluminium have a multiphase structure. These alloys contain network with high values of tensile strain. The microstructure of the samples was investigated and behaviour of dislocations in the alloys was analysed by Transmission electron microscopy methods (TEM.

  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. Characteristics on Bi-Pb Based Alloys Quenched from Melt

    Institute of Scientific and Technical Information of China (English)

    Rizk Mostafa Shalaby

    2009-01-01

    Three different bismuth-lead systems namely, Wood's alloy (Bi50Pb25Sn12.5Cd12.5), Newton's alloy (Bi50Pb31.2Sn18.8) and Rose's alloy (Bi50Pb28Sn22), with one used as fusible alloys were quenched from melt by melt spinning technique. Thermal analysis, structure and mechanical properties of all alloys have been studied and analyzed. From X-ray diffraction analysis, an intermetallic compound phase, designated Pb7Bi3 is detected. The formation of an intermetallic compound phase causes a pronounced increase in the electrical resistivity. The Wood's alloy containing-cadmium exhibits mechanical properties superior to both the Newton's and Rose's alloys. The presence of cadmium in Wood's alloy decreases its melting point. Wood's alloy has better properties, which make it useful in various applications such as in protection shields for radiotherapy, locking of mechanical devices and welding at low temperature.

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Al-Assiri, M.S., E-mail: msassiri@kku.edu.sa [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); El-Desoky, M.M., E-mail: mmdesoky@gmail.com [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt)

    2011-09-08

    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 BaTiO{sub 3}-V{sub 2}O{sub 5}-Bi{sub 2}O{sub 3} have been transformed into glass-ceramic nano-composites by annealing at crystallization temperature T{sub cr} determined from DSC thermograms. After annealing they consist of small crystallites embedded in glassy matrix. The crystallization temperature T{sub cr} increases with increasing BaTiO{sub 3} 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 V{sup 4+}-V{sup 5+} 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.

  11. 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.

  12. 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.

  13. 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 ...

  14. Materials Properties of Modifeied Ni-Based Alloy

    Directory of Open Access Journals (Sweden)

    Kraus, L.

    2007-01-01

    Full Text Available The thermomechanical processing of NiMoCr solid solution nickel base superalloy is the way to considerably influence the grain size. As uniform coarse grain size increases the creep strength and crack growth resistance. In the work, the processing to achieve uniform recrystallized grain structure with variation of thermomechanical parameters is investigated. The creep behavior of the alloy after various hot working conditions is determined. The results of creep tests showed that creep characteristics such as strain rate and lifetime were greatly dependent on the initial hot working conditions and annealing parameters.

  15. 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

  16. 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)

  17. 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.

  18. 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.

  19. 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

  20. Mechanochemical method for producing iron-based nitrogen-containing nanocrystalline alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Iron-based products account the main volume of powder metallurgy production. Nevertheless its strength and reliability are not enough in comparison with classical cast materials. So that is why making nanostructural powder materials allows to increase strength and extend the range of products. A principally new way of nanostructure production is possible by means of iron mechanical alloying with nitride-forming and nitrogen both at the same time.Unlike classical technology of internal nitrogenation, nitrogen saturation, in our case, occurs by whole volume at plastic deformation conditions. A review of experimental results of phase forming alloys in the Fe-Ni, Fe-Ni-Cr, Fe-Ni-N, Fe-Ni-Cr-N, Fe-Cr-Ni systems prepared by mechanical alloying are given. The influence of the technological parameters of mechanical alloying, atmosphere of mechanical activation on nitrogen content and phase composition of examined alloys has been studied. Experimental results of the influence of mechanical alloying technological parameters on degree of ammonia dissociation and nitrogen content in examined alloys are presented. Heat treatment influence of mechanically alloyed, nitrogen-containing alloys on theirphase composition and structure are investigated.It was shown that using mechanical alloying, it's possible to prepare high-alloyed iron-based alloys containing more than 1% of nitrogen. It was established that technology of mechanical alloying in ammonia atmosphere allows to prepare austenitic steels with nanocrystalline structure, which affords high value of yield stress. Physico-chemical patterns of interaction between the nitrogen-containing atmosphere and nitride-forming elements under their mutual mechanical activation conditions were established in consequence of theoretical and experimental researches. Some scientific principles of nanocrystalline materials were gained by quantitative description of correlation between the mechanical dose, nitrogen potertial, nitrogen content

  1. 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)

  2. 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.

  3. 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.

  4. High temperature oxidation behavior of ODS iron-base alloys for nuclear energy application

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Zhou, Z.; Liao, L.; Chen, W.; Ge, C. [Univ. of Science and Technology Beijing, School of Materials Science and Engineering, Beijing (China)

    2010-07-01

    Oxide dispersion strengthened (ODS) iron based alloys are considered as promising high temperature structural material for advanced nuclear energy systems due to its higher creep strength and radiation damage resistance than conventional commercial steels. In this study, the oxidation behavior of ODS iron based alloys with different Cr content (12-18%) was investigated by exposing samples at high temperature of 700℃ and 1000℃ in atmosphere environment, the exposure time is up to 500 h. Results showed that 14Cr and 18Cr ODS alloys exhibited better oxidation resistance than 12Cr ODS alloys. For the same chromium content, the oxidation resistance of ODS alloys are better than that of non-ODS alloys. (author)

  5. 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.

  6. Laser cladding of Ni-based alloy on copper substrate

    Institute of Scientific and Technical Information of China (English)

    Fang Liu; Changsheng Liu; Xingqi Tao; Suiyuan Chen

    2006-01-01

    The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope (OM), scanning electron microscope (SEM), and X-Ray diffraction (XRD). The average microhardness of the cladding coating was Hv 280, which was almost three times of that of the Cu substrate (Hv 85). OM and SEM observations showed that the obtained coating had a smooth and uniform surface, as well as a metallurgical combination with the Cu substrate without cracks and pores at the interface. With the addition of copper into the nickel-based alloy, the differences of thermal expansion coefficient and melting point between the interlayer and cladding were reduced, which resulted in low stresses during rapid cooling. Moreover, large amount of (Cu, Ni) solid solution formed a metallurgical bonding between the cladding coating and the substrate, which also relaxed the stresses, leading to the reduction of interfacial cracks and pores after laser cladding.

  7. The wettability of Fe based alloy on TiO

    Institute of Scientific and Technical Information of China (English)

    李庆奎; 钟海云; 钟晖; 戴艳阳

    2002-01-01

    For developing TiO based imitated gold materials, the wettabilities of Fe and Fe-Cr-Ni-Ti on TiO were studied. The results indicated that the wettabilities of Fe and Fe-Cr on TiO were poor, and their wetting angles were about 90° at melting point. The wetting angles reduced with the increase of wetting temperature, but the influence of temperature was small. Fe and Fe-Cr containing Cr 50% or less could react with TiO on the interface to form Fe2Ti and Ti2O3, but this did not improve the wettability effectively. When Ni-Ti was added into Fe-Cr alloy, Ni3Ti was formed on the interface, which can reduce the interface energy, improve the wettability, and prevent the formation of Fe2Ti and Ti2O3. The wetting angles could go down to about 40° when 3% Ni-Ti was added to Fe-Cr alloy.

  8. 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.

  9. 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

  10. 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...

  11. 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)

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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

  17. 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.

  18. A Palladium-Based Alloy for Prosthetic Dentistry:Structure and Properties

    Institute of Scientific and Technical Information of China (English)

    STEPANOVA Galina; PARUNOV Vitaly; VASEKIN Vasily; KAREVA Maria; SINAGEJKINA Julia

    2012-01-01

    Abstract.Using the results of physical and chemical researches and mechanical tests of the Pd-Au-Cu-Sn system alloys,a new palladium-based alloy has been chosen and studied in detail.It has a higher plasticity and a lower hardness than the Palladent alloy,widely used in prosthetic dentistry:its hardness is lower than 300 MPa,and its specific elongation is 10%~14 %.At the same time,such important practical characteristics of the alloys as the strength of adhesion to ceramics and thermal expansion coefficient are almost similar.

  19. Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys

    Science.gov (United States)

    Maltsev, Dmitry S.; Volkovich, Vladimir A.; Yamshchikov, Leonid F.; Chukin, Andrey V.

    2016-09-01

    Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys were studied. Temperature dependences of gadolinium activity in the studied alloys were determined at 573-1073 K employing the EMF method. Solubility of gadolinium in the Ga-Sn and Ga-Zn alloys was measured at 462-1073 K using IMCs sedimentation method. Activity coefficients as well as partial and excess thermodynamic functions of gadolinium in the studied alloys were calculated on the basis of the obtained experimental data.

  20. 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

  1. 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

  2. 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.

  3. Barium aspiration and alveolarisation of barium in an infant: A case report and review of management

    Directory of Open Access Journals (Sweden)

    Alan F. Isles

    2014-05-01

    Full Text Available We describe a case of bilateral inhalation and alveolarisation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-oesophageal cleft. We review the literature on barium aspiration, its consequences and make recommendations for management.

  4. 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.)

  5. 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.

  6. 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...

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

    Science.gov (United States)

    Ivanov, Yurii; Rygina, Mariya; Petrikova, Elizaveta; Krysina, Olga; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina

    2016-01-01

    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.

  8. Precipitation hardening in Fe--Ni base austenitic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, K.M.

    1979-05-01

    The precipitation of metastable Ni/sub 3/X phases in the austenitic Fe--Ni-base alloys has been investigated by using various combinations of hardening elements, including Ti, Ta, Al, and Nb. The theoretical background on the formation of transition precipitates has been summarized based on: atomic size, compressibility, and electron/atom ratio. A model is proposed from an analysis of static concentration waves ordering the fcc lattice. Ordered structure of metastable precipitates will change from the triangularly ordered ..gamma..', to the rectangularly ordered ..gamma..'', as the atomic ratio (Ti + Al)/(Ta + Nb) decreases. The concurrent precipitation of ..gamma..' and ..gamma..'' occurs at 750/sup 0/C when the ratio is between 1.5 and 1.9. Aging behavior was studied over the temperature range of 500/sup 0/C to 900/sup 0/C. Typical hardness curves show a substantial hardening effect due to precipitation. A combination of strength and fracture toughness can be developed by employing double aging techniques. The growth of these coherent intermediate precipitates follows the power law with the aging time t : t/sup 1/3/ for the spherical ..gamma..' particles; and t/sup 1/2/ for the disc-shaped ..gamma..''. The equilibrium ..beta.. phase is observed to be able to nucleate on the surface of imbedded carbides. The addition of 5 wt % Cr to the age-hardened alloys provides a non-magnetic austenite which is stable against the formation of mechanically induced martensite.Cr addition retards aging kinetics of the precipitation reactions, and suppresses intergranular embrittlement caused by the high temperature solution anneal. The aging kinetics are also found to be influenced by solution annealing treatments.

  9. On the formation of ultra-fine grained Fe-base alloys via phase transformations

    NARCIS (Netherlands)

    Chezan, AR; Craus, CB; Chechenin, NG; Vystavel, T; Niesen, L; De Hosson, JTM; Boerma, DO

    2004-01-01

    This paper concentrates on the formation of ultra-fine grained Fe-base alloys via phase transformations. In particular the manipulation of the microstructure of Fe-Ni-Ti and Fe-Ni-Cr alloys via phase cycling in the Fe-N system was investigated. Transitions between bcc (alpha-Fe), fee (gamma'-Fe4N) a

  10. 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

  11. Infection free titanium alloys by stabile thiol based nanocoating.

    Science.gov (United States)

    Cökeliler, Dilek; Göktaş, Hilal; Tosun, Pinar Deniz; Mutlu, Selma

    2010-04-01

    As biomedical materials, titanium and titanium alloys (Ti-6Al-4V) are superior to many materials in terms of mechanical properties and biocompatibility. However, they are still not sufficient for prolonged clinical use because the biocompatibility of these materials must be improved. In this study, the prevention of the attachment of test microorganism on the Ti alloy surfaces by thiol (-SH) and hydroxyl (-OH) functional group containing monomer in plasma based electron beam generator was reported in order to prepare anti-fouling surfaces. The precursor, 11-mercaptoundecanoic acid is used as plasma source to create nano-film with 30-60 nm approximately. The surface chemistry and topology of uncoated and coated samples are characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Static contact angle measurements are performed to state the change of surface hydrophilicity. All coated samples are tested in-vitro environment with Staphylococcus epidermidis that is chosen as the test bacteria strain in view of its significance for the pathogenesis of medical-device-related infections. This test is repeated after certain period of times and samples are waited in dynamic fluid media in order to investigate the stability of nano-coating. Plasma polymerized 11-mercaptoundecanoic acid film (PP MUA) with 42 +/- 4 nm is found alternative, stabile and simple method to create bacterial anti-fouling surfaces. The static contact angle of the coated surface is 34 +/- 80 whereas the uncoated surface is 57 +/- 50. For the coated surface, the presence of C-OH and C==O groups in infrared spectra defining the PP MUA is achieved by the plasma polymerization. The attachment of the model microorganism on the biomaterial surface prepared by PP MUA is reduced 85.3% if compared to unmodified control surface.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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)

  18. Laser cooling and trapping of barium

    NARCIS (Netherlands)

    De, Subhadeep

    2008-01-01

    Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers a

  19. 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.

  20. 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

  1. 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.

  2. 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...

  3. 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...

  4. 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.

  5. 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

  6. 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.

  7. Martensitic transformation and related magnetic effects in Ni-Mn-based ferromagnetic shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    Wang Dun-Hui; Han Zhi-Da; Xuan Hai-Cheng; Ma Sheng-Can; Chen Shui-Yuan; Zhang Cheng-Liang; Du You-Wei

    2013-01-01

    Ferromagnetic shape memory alloys,which undergo the martensitic transformation,are famous multifunctional materials.They exhibit many interesting magnetic properties around the martensitic transformation temperature due to the strong coupling between magnetism and structure.Tuning magnetic phase transition and optimizing the magnetic effects in these alloys are of great importance.In this paper,the regulation of martensitic transformation and the investigation of some related magnetic effects in Ni-Mn-based alloys are reviewed based on our recent research results.

  8. Experimental Study on Machining Shape Hole of Ni-based Super-heat-resistant Alloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Inconel 718 and Waspaloy, Nickel-based super-heat-resistant alloy, are high-strength, thermal-resistant and corrosion-resistant alloy that are widely used in parts of gas turbines and airplane engines. Due to their extremely tough and thermal-resistant nature, they are well known as materials that are difficult to cut. Shape holes on a disc of an aircraft engine, made of Ni-based super-heat-resistant alloy, are required with good surface integrity and geometric accuracy. This kind of shape hole is produced ...

  9. 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.

  10. 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.

  11. Oxidation behaviour of experimental Co-Re-base alloys in laboratory air at 1000 C

    Energy Technology Data Exchange (ETDEWEB)

    Klauke, Michael; Mukherji, Debashis; Roesler, Joachim [Technische Universitaet Braunschweig, Institut fuer Werkstoffe (Germany); Gorr, Bronislava; Christ, Hans-Juergen [Universitaet Siegen, Institut fuer Werkstofftechnik (Germany); Braz da Trindade Filho, Vicente [Vallourec und Mannesmann Tubes, Duesseldorf (Germany)

    2009-01-15

    The oxidation behaviour of experimental Co-Re-based alloy at 1000 C was studied. A set of binary, ternary and quaternary alloys from the Co-Re-Cr-C system was used as model alloys to understand the role each alloying element plays on oxidation. The morphology and composition of the oxide scale that formed was analysed by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. It was found that the present Co-Re alloys with 23 at.% and 30 at.% Cr additions behaved very similarly to Co-Cr binary alloys with equivalent Cr content. The oxide scale was multilayered, consisting of a dense CoO outer layer, a porous mixed oxide layer containing Co-oxide and Co-Cr spinel, and a discontinuous and non-protective Cr{sub 3}O{sub 2} layer. The binary Co-Re alloy behaved differently in oxidation, and it formed only a monolithic CoO scale. However, Re in combination with Cr promotes Cr-Re-rich {sigma} phase formation, which oxidises preferentially compared to the Co matrix. Carbon ties up part of the Cr to form Cr{sub 23}C{sub 6} type carbides. However, these carbides are not stable at 1000 C and dissolved with time, therefore C had only a minor role in the oxidation behaviour. In general, increasing Cr content in the alloy improved oxidation resistance. (orig.)

  12. 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.

  13. 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.

  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. Rapid iodometric determination of copper in some copper-base alloys

    NARCIS (Netherlands)

    Agterdenbos, J.; Eelberse, P.A.

    1966-01-01

    Copper-base alloys, especially those containing tin, are readily dissolved in a mixture of hydrofluoric and nitric acids. In the resulting solution copper can be titrated iodometrically in the conventional manner.

  16. Investigation on low activated materials on the base of V-Ti-Cr alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Low activated materials on the base of vanadium are among the key materials for future fusion reactors. In the Russian Federation the long term National Program on the development of such vanadium alloys is under the way.

  17. Investigation on low activated materials on the base of V-Ti-Cr alloys

    Institute of Scientific and Technical Information of China (English)

    Potapenko; M.; Shikov; A.; Chernov; V.; Drobishev; V.; Gubkin; I.

    2005-01-01

    Low activated materials on the base of vanadium are among the key materials for future fusion reactors. In the Russian Federation the long term National Program on the development of such vanadium alloys is under the way.……

  18. 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...

  19. 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.

  20. 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)

  1. MACHINING OF NICKEL BASED ALLOYS USING DIFFERENT CEMENTED CARBIDE TOOLS

    Directory of Open Access Journals (Sweden)

    BASIM A. KHIDHIR

    2010-09-01

    Full Text Available This paper presents the results of experimental work in dry turning of nickel based alloys (Haynes – 276 using Deferent tool geometer of cemented carbide tools. The turning tests were conducted at three different cutting speeds (112, 152, 201and 269 m/min while feed rate and depth of cut were kept constant at 0.2 mm/rev and 1.5 mm, respectively. The tool holders used were SCLCR with insert CCMT-12 and CCLNR – M12-4 with insert CNGN-12. The influence of cutting speed, tool inserts type and workpiece material was investigated on the machined surface roughness. The worn parts of the cutting tools were also examined under scanning electron microscope (SEM. The results showed that cutting speed significantly affected the machined surface finish values in related with the tool insert geometry. Insert type CCMT-12 showed better surface finish for cutting speed to 201 m/min, while insert type CNGN-12 surface roughness increased dramatically with increasing of speed to a limit completely damage of insert geometer beyond 152 m/min.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Improvement of Creep and High Temperature Tensile Properties by Adding W to Orthorhombic Ti2AlNb-Based Alloys

    Institute of Scientific and Technical Information of China (English)

    Fang Tang; Satoshi Emura; Masuo Hagiwara

    2000-01-01

    The Orthorhombic Ti2AlNb-based alloys (O alloys) are potential high temperature materials for applications in aircraft engines for their high specific strength. In this paper, with the purpose of enhancing the mechanical properties, W is added to O alloys as the quarternary alloying element. The effects of W additive on the high temperature tensile properties and creep resistance are investigated. The effects of boron doping on these properties are also studied.

  7. Thermal Fatigue Behaviour of Co-Based Alloy Coating Obtained by Laser Surface Melt-Casting on High Temperature Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A thermal fatigue behaviour of C o-based alloy coating obtained by laser surface melt-casting on the high tempe rature alloy GH33 was studied. The results show that after each time of thermal cycling, the final residual stress was formed in the melt-casting layer which is attributed to the thermal stress and structural stress. Through the first 50 times of thermal cycling, the morphology of coating still inherits the laser casting one, but the dendrites get bigger; After the second 50 times of thermal cycling, corrosion pits emerge from coating, and mostly in the places where coating and substrate meet. The fatigue damage type of coating belongs to stress corrosi on.

  8. 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.

  9. 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)

  10. Commercialization status of Ni{sub 3}Al-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-31

    The Ni{sub 3}Al-based alloys have been under development at the Oak Ridge National Laboratory (ORNL) and other research institutions in the United States and around the world for the last ten years. The incremental developments of composition, melting process, casting methods, property data, corrosion data, weldability development, and prototype component testing under production-like operating conditions have pushed the ORNL-developed Ni{sub 3}Al-based alloys closer to commercialization. This paper will present the highlights of incremental technical developments along with the approach and current status of commercialization. It is concluded that cast components are the primary applications of Ni{sub 3}Al-based alloys, and applications range from heat-treating fixtures of forging dies. It is also concluded that the commercialization process is accelerated when technology is licensed to an organization that can produce the alloy, has component manufacturing capability, and is also a user.

  11. 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.

  12. Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

    Institute of Scientific and Technical Information of China (English)

    ZHUO Long-Chao; PANG Shu-Jie; WANG Hui; ZHANG Tao

    2009-01-01

    Based on a new approach for designing glassy alloy compositions,bulk Al-based alloys with good glass-forming ability (GFA) are synthesized.The cast Al86Si0.5Ni4.06Co2.94 Y6Sc0.5 rod with a diameter of 1 mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod.The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 Gpa and maximum strength of 1.27 Gpa as well as an obvious plastic strain of about 2.4% during compressive deformation.This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability.

  13. 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.

  14. 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.)

  15. 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

  16. 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.

  17. 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...

  18. 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.)

  19. X-ray elastic constant determination and residual stress of two phase TiAl-based intermetallic alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To evaluate the residual stress in TiAl-based alloys by X-ray diffraction, X-ray elastic constants (REC) of a γ-TiAl alloy were determined. From these results, the stress state of a given phase in a duplex TiAl-based alloy under a uniaxial tensile loading has been characterized by X-ray diffraction. The results show that the X-ray elastic constants and the microscopic stresses of the given phase are different from the apparent elastic constants and the macroscopic stresses of the alloy. The reason of the different distribution of the alloy was also discussed.

  20. 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

  1. 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

  2. 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.

  3. 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.

  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. 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)

  7. 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...

  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. 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.

  10. 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)

  11. Microstructure of Ni-Based Self-Fluxing Alloy Coating (PartⅠ)

    Institute of Scientific and Technical Information of China (English)

    WANG Jin-hua; Milan Friesel; Magnus Willander; Richard Warren

    2005-01-01

    The microstructure of a Ni-based self-fluxing alloy coating produced by an oxygen-acetylene flame spraying Ni-16.5Cr-3.3B-4.7Si-4. 4Fe-0. 8C system alloy powder onto a common steel substrate was investigated by microanalysis methods. The phases in the coating were observed by SEM and determined by XEDS X-Ray energy spectrum and X-Ray diffraction patterns. Meanwhile, some molecular formulas were calculated.

  12. 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.

  13. 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.)

  14. 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.

  15. 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.

  16. 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.

  17. Neutral Barium Cloud Evolution at Different Altitudes

    Institute of Scientific and Technical Information of China (English)

    李磊; 徐荣栏

    2002-01-01

    Considering the joint effects of diffusion, collision, oxidation and photoionization, we study the evolution of the barium cloud at different altitudes in the space plasma active experiment. The results present the variation of the loss rate, number density distribution and brightness of the barium cloud over the range from 120 to 260km.This can be divided into oxidation, oxidation plus photoionization and photoionization regions.

  18. Small barium rail gun for plasma injection.

    Science.gov (United States)

    Kiwamoto, Y

    1980-03-01

    A small rail gun with a barium electrode can be operated at higher than one shot per second to produce more than 2x10(16) barium ions with energy 10-20 eV. The operation of the gun takes advantage of the external magnetic field for cross-field plasma injection into a trap. Up to 7 kG of the magnetic field examined, the gun performance improves with the increased magnetic field strength.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. Effect of solution hardening on the shape memory effect of Fe-Mn based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzaki, K.; Natsume, Y.; Maki, T. [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering; Tomota, Y. [Ibaraki Univ., Hitachi (Japan)

    1995-10-01

    Fe-high Mn-Si alloys, which undergo {gamma} (fcc) to {var_epsilon} (hcp) martensitic transformation, exhibit a pronounced shape memory effect. The origin of shape memory effect of these alloys is the reversion of stress-induced {var_epsilon} martensite. A shape change must hence be accomplish3ed by stress-induced martensitic transformation without permanent slip in austenite ({gamma}) in order to obtain a good shape memory effect. It is clear that the intrusion of permanent slip can be suppressed by increasing the strength of austenite and by decreasing the applied stress required for a shape change due to stress-induced martensitic transformation. It has been reported that the addition of the interstitial elements of C and N as well as the substitutional elements of Mo and V increases the 0.2% proof stress of austenite in Fe-high Mn alloys. However, there have been few studies on the effect of these alloying elements on the shape memory effect of Fe-high Mn based alloys. In the present study, it was aimed to improve the shape memory effect of Fe-high Mn based alloys by the strengthening of austenite through solution hardening due to C and Mo.

  9. Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Guo J.

    2015-06-01

    Full Text Available Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.

  10. Physical Simulation of Friction Stir Welding and Processing of Nickel-Base Alloys Using Hot Torsion

    Science.gov (United States)

    Rule, James R.; Lippold, John C.

    2013-08-01

    The Gleeble hot torsion test was utilized in an attempt to simulate the friction stir-processed microstructure of three Ni-base alloys: Hastelloy X, Alloy 625, and Alloy 718. The simulation temperatures were based on actual thermal cycles measured by embedded thermocouples during friction stir processing of these alloys. Peak process temperatures were determined to be approximately 1423 K (1150 °C) for Hastelloy X and Alloy 625 K and 1373 K (352 °C and 1100 °C) for Alloy 718. The peak temperature and cooling rates were programed into the Gleeble™ 3800 thermo-mechanical simulator to reproduce the stir zone and thermo-mechanically affected zone (TMAZ) microstructures. The TMAZ was successfully simulated using this technique, but the stir zone microstructure could not be accurately reproduced, with hot torsion samples exhibiting larger grain size than actual friction stir processing trials. Shear stress and strain rates as a function of temperature were determined for each material using hot torsion simulation.

  11. 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.

  12. Corrosion Performance of Fe-Based Alloys in Simulated Oxy-Fuel Environment

    Science.gov (United States)

    Zeng, Zuotao; Natesan, Ken; Cai, Zhonghou; Rink, David L.

    2016-09-01

    The long-term corrosion of Fe-based alloys in simulated oxy-fuel environment at 1023 K (750 °C) was studied. Detailed results are presented on weight change, scale thickness, internal penetration, microstructural characteristics of the corrosion products, and the cracking of scales for the alloys after exposure at 1023 K (750 °C) for up to 3600 hours. An incubation period during which the corrosion rate was low was observed for the alloys. After the incubation period, the corrosion accelerated, and the corrosion process followed linear kinetics. Effects of alloy, CaO-containing ash, and gas composition on the corrosion rate were also studied. In addition, synchrotron nanobeam X-ray analysis was employed to determine the phase and chemical composition of the oxide layers on the alloy surface. Results from these studies are being used to address the long-term corrosion performance of Fe-based alloys in various coal-ash combustion environments and to develop methods to mitigate high-temperature ash corrosion.

  13. 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.

  14. 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)

  15. 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 on the 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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.)

  2. 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

  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. Ion bombardment of Fe-based amorphous metallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, Marcel, E-mail: marcel.miglierini@stuba.sk [Slovak University of Technology, Department of Nuclear Physics and Technology (Slovakia); Lancok, Adriana [AS CR, v. v. i., Institute of Physics (Czech Republic); Pavlovic, Marius [Slovak University of Technology, Department of Nuclear Physics and Technology (Slovakia)

    2009-02-15

    Fe{sub 74}Cu{sub 1}Nb{sub 3}Si{sub 16}B{sub 6} amorphous metallic alloy is investigated after ion irradiation by 110 keV N{sup +} and 593 MeV Au ions. The depth-profiles of the radiation damage were calculated by the SRIM2008 code. Applicability of transmission and conversion electron Moessbauer effect measurements to distinguish between the bulk and surface radiation damage is demonstrated by using different irradiation conditions. The investigated alloy is characterized by ferromagnetic interactions. The implantation does not depict appreciable changes of the samples' surfaces. Changes in chemical short-range order (SRO) are revealed in N{sup +} irradiated alloys. Heavy Au ions caused pronounced effects in the position of the net magnetization though no impact on SRO was observed. After annealing, structural relaxation and annealing-out of the irradiation-induced stresses caused the rotation of the net magnetization back to its original position.

  5. 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.

  6. Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water

    Science.gov (United States)

    Kato, Masashi; Kumasaka, Mayuko Y.; Ohnuma, Shoko; Furuta, Akio; Kato, Yoko; Shekhar, Hossain U.; Kojima, Michiyo; Koike, Yasuko; Dinh Thang, Nguyen; Ohgami, Nobutaka; Ly, Thuy Bich; Jia, Xiaofang; Yetti, Husna; Naito, Hisao; Ichihara, Gaku; Yajima, Ichiro

    2013-01-01

    Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system. PMID:23805262

  7. Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water.

    Directory of Open Access Journals (Sweden)

    Masashi Kato

    Full Text Available Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L and coexposure to barium (137 µg/L and arsenic (225 µg/L. The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L and barium (700 µg/L, but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium, in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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)

  14. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    Directory of Open Access Journals (Sweden)

    Yinghong Li, Liucheng Zhou, Weifeng He, Guangyu He, Xuede Wang, Xiangfan Nie, Bo Wang, Sihai Luo and Yuqin Li

    2013-01-01

    Full Text Available We investigated the strengthening mechanism of laser shock processing (LSP at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Tailored microstructure creation of TiAl-based refractory alloys within VGF solidification

    Energy Technology Data Exchange (ETDEWEB)

    Kartavykh, A.V., E-mail: karta@korolev-net.ru [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation); Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str., 142190 Troitsk, Moscow (Russian Federation); Tcherdyntsev, V.V.; Gorshenkov, M.V.; Podgorny, D.A.; Borisova, Yu.V. [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation)

    2013-09-16

    The work is aimed at the study of the formation and refinement of primary microstructure appearing in the refractory lightweight structural TiAl-based intermetallics during their solidification from the melt. The alloy with Ti–46Al–8Nb (at.%) nominal composition is selected for applied study in microstructure engineering. For tailored microstructure development, the Directional Solidification (DS) of pre-synthesized alloy was performed in the vertical multizone electro-furnace by Vertical Gradient Freezing (VGF) power-down technique in pure argon environment. Both columnar-dendrite, and equiaxed-granular reproducible as-cast microstructures have been produced in DS ingots, basing onto Columnar-to-Equiaxed Transition (CET) diagram exploration. Particular attention was paid further to equiaxed microstructure improvement by combination of modifying doping of alloy with boron grain refiner and VGF processing. As a result the perfect inoculated microstructure of Ti–44Al–7Nb–2B (at.%) ingots was produced with 120 μm mean grain diameter, low scattering of dimensional characteristics and high tolerance to DS process parameters variation. DS samples were examined by SEM microanalysis along with EBSD and Auger spectrometry of boride particles in the alloy matrix. The nature, state and exact composition of precipitated borides are discussed along with the nucleation mechanism in relation to the literature data. - Highlights: • Columnar-dendrite and granular structures created by directional solidification in Ti–46Al–8Nb ingots. • Ti–44Al–7Nb–2B (at.%) grain refined alloy produced at TiB{sub 2} alloying. • TiB{sub 2} dissolved and re-precipitated into (Ti,Nb)B phase, where Ti/Nb ratio is 1:1. • Hypothesis: Nb from heavily alloyed melt can substitute Ti in TiB precipitates up to NbB. • State and nucleation efficacy of (Ti,Nb)B can depend on Nb content through Ti/Nb ratio.

  20. 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

  1. 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...

  2. Ultrahigh performance of Ti-based glassy alloy tube sensor for Coriolis mass flowmeter

    Institute of Scientific and Technical Information of China (English)

    MA Chao-li; A. INOUE; ZHANG Tao

    2006-01-01

    Bulk metallic glasses (BMGs) have potential applications for both structural and functional components owing to their good mechanical properties. With the aim of demonstrating great engineering value of BMGs, a direct melt-forming technique based on suction casting for the production of glassy alloy tubes was developed. The fabrication, structure, geometry, properties and sensor performance of the tubes were examined. The results show that the Coriolis mass flowmeters using the Ti-based glassy alloy sensor tube exhibit excellent measurement sensitivity, viz. 28.5 times higher than that of the conventional flowmeter manufactured using stainless steel (SUS316) tube.

  3. 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.

  4. 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.

  5. Morphology and Magnetic Properties of Electrodeposited Iron and Nickel Based Alloy Foils

    Institute of Scientific and Technical Information of China (English)

    GUO Zhan-cheng; LIU Mei-feng; SUN Chun-wen; LIU Yu-xing; LU Wei-chang

    2004-01-01

    An alternative to conventional process for the preparation of soft magnetic metal foils of Fe, Fe-Ni, Fe-Co and Fe-Ni-Co by electroforming was described. The microstructure and magnetic properties were observed. The results showed that the crystal size of the iron-based alloy foil is less than 10 μm, while that of nickel-based alloy foil is about 2 μm. Moreover, the electroformed Fe-Ni foil has better magnetic properties than the conventional milled permalloy 1J79 foil.

  6. 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.

  7. Irradiation effects in oxide dispersion strengthened (ODS) Ni-base alloys for Gen. IV nuclear reactors

    Science.gov (United States)

    Oono, Naoko; Ukai, Shigeharu; Kondo, Sosuke; Hashitomi, Okinobu; Kimura, Akihiko

    2015-10-01

    Oxide particle dispersion strengthened (ODS) Ni-base alloys are irradiated by using simulation technique (Fe/He dual-ion irradiation) to investigate the reliability to Gen. IV high-temperature reactors. The fine oxide particles with less than 10 nm in average size and approximately 8.0 × 1022 m-3 in number density remained after 101 dpa irradiation. The tiny helium bubbles were inside grains, not at grain-boundaries; it is advantageous effect of oxide particles which trap the helium atoms at the particle-matrix interface. Ni-base ODS alloys demonstrated their great ability to overcome He embrittlement.

  8. 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-...

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

    Energy Technology Data Exchange (ETDEWEB)

    Tian, J.W. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Dai, K. [Quality Engineering and Software Technology, East Hartford, CT 06108 (United States); Villegas, J.C. [Intel Corporation, Chandler, AZ (United States); Shaw, L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)], E-mail: leon.shaw@uconn.edu; Liaw, P.K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Klarstrom, D.L. [Haynes International, Inc., Kokomo, IN (United States); Ortiz, A.L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071 Badajoz (Spain)

    2008-10-15

    A surface severe plastic deformation (S{sup 2}PD) 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 S{sup 2}PD 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.

  10. 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

  11. 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

  12. Potentiality of the "Gum Metal" titanium-based alloy for biomedical applications.

    Science.gov (United States)

    Gordin, D M; Ion, R; Vasilescu, C; Drob, S I; Cimpean, A; Gloriant, T

    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.

  13. 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.

  14. 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.

  15. Progress in research on cold crucible directional solidification of titanium based alloys

    Directory of Open Access Journals (Sweden)

    Chen Ruirun

    2014-07-01

    Full Text Available Cold crucible directional solidification (CCDS is a newly developed technique, which combines the advantages of the cold crucible and continuous melting. It can be applied to directionally solidify reactive, high purity and refractory materials. This paper describes the principle of CCDS and its characteristics; development of the measurement and numerical calculation of the magnetic field, flow field and temperature field in CCDS; and the CCDS of Ti based alloys. The paper also reviews original data obtained by some scholars, including the present authors, reported in separate publications in recent years. In Ti based alloys, Ti6Al4V, TiAl alloys and high Nb-containing TiAl alloys, have been directionally solidified in different cold crucibles. The crosssections of the cold crucibles include round, near rectangular and square with different sizes. Tensile testing results show that the elongation of directionally solidified Ti6Al4V can be improved to 12.7% from as cast 5.4%. The strength and the elongation of the directionally solidified Ti47Al2Cr2Nb and Ti44Al6Nb1.0Cr2.0V are 650 MPa/3% and 602.5 MPa/1.20%, respectively. The ingots after CCDS can be used to prepare turbine or engine blades, and are candidates to replace Ni super-alloy at temperatures of 700 to 900 °C.

  16. 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)

  17. 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.

  18. Indoor environmental corrosion of Ag-based alloys in the Egyptian Museum (Cairo, Egypt)

    Science.gov (United States)

    Ingo, G. M.; Angelini, E.; Riccucci, C.; de Caro, T.; Mezzi, A.; Faraldi, F.; Caschera, D.; Giuliani, C.; Di Carlo, G.

    2015-01-01

    In this study, we have investigated the indoor environmental corrosion of Ag-based alloys after long-term exposure in a showcase of an exhibition room and in the open atmosphere at the Egyptian Museum of Cairo (Egypt). In order to simulate the corrosion processes that occur at the surface of archaeological artefacts, Ag-based alloys with chemical composition, metallurgical features and micro-chemical structure similar to those of ancient alloys have been purposely produced as sacrificial reference samples. Our findings show that corrosion phenomena on alloy surface are mainly caused by environmental sulphur and chlorine containing species that react in different ways depending on the exhibition conditions and on the alloy composition. This approach allows to identify the degradation agents and mechanisms that really take place at the surface of objects similar to ancient artefacts without the necessity of sampling them. Moreover, it is possible to get useful indications for the safe storage or exhibition of silver archaeological artefacts, their cleaning and conservation.

  19. 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.

  20. 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)

  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. 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)

  3. 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

  4. Coherent Dark Resonances in Atomic Barium

    CERN Document Server

    Dammalapati, U; Jungmann, K; Willmann, L

    2007-01-01

    The observation of dark-resonances in the two-electron atom barium and their influence on optical cooling is reported. In heavy alkali earth atoms, i.e. barium or radium, optical cooling can be achieved using n^1S_0-n^1P_1 transitions and optical repumping from the low lying n^1D_2 and n^3D_{1,2} states to which the atoms decay with a high branching ratio. The cooling and repumping transition have a common upper state. This leads to dark resonances and hence make optical cooling less inefficient. The experimental observations can be accurately modelled by the optical Bloch equations. Comparison with experimental results allows us to extract relevant parameters for effective laser cooling of barium.

  5. 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

  6. Grain refinement of permanent mold cast copper base alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sadayappan, M.; Thomson, J. P.; Elboujdaini, M.; Gu, G. Ping; Sahoo, M.

    2004-04-29

    control tool was proved in two foundries. The method can also correctly predict the onset of fading. The corrosion resistance of the grain refined alloys was measured in two solutions having different hydrogen activities, pH 6 and pH8, and compared with the base alloys. Potentiodynamic polarization and long term weight loss experiments were conducted to evaluate the corrosion resistance. Cu-Zn alloys were evaluated for dezincification. In general, the grain refined alloys performed marginally better than the base alloys.

  7. 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.

  8. Refractory oxides containing aluminium and barium

    OpenAIRE

    Davies T.J.; Biedermann M.; Q-G. Chen; Emblem H. G.; Al-Douri W. A.

    1998-01-01

    Oxides containing aluminium and barium, optionally with chromium, are refractory with several possible industrial uses. A gel precursor of an oxide having the formula BaO.n(Al2xCr2yO3), where 1barium salt with a solution of an aluminium salt or a solution of an aluminium salt and a chromium III salt, then forming a gel which was fired to obtain the desired oxide. Filaments may be drawn as the gel is forming or extr...

  9. Electronic structure of nanograin barium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Xiangyun; WANG Xiaohui; LI Dejun; LI Longtu

    2007-01-01

    The density of states and band structure of 20 nm barium titanate(BaTiO3,BT)ceramics are investigated by first-principles calculation.The full potential linearized augmented plane wave(FLAPW)method is used and the exchange correlation effects are treated by the generalized gradient approximation(GGA).The results show that there is substantial hybridization between the Ti 3d and O 2p states in 20 nm BT ceramics and the interaction between barium and oxygen is typically ionic.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Boundary Engineering for the Thermoelectric Performance of Bulk Alloys Based on Bismuth Telluride.

    Science.gov (United States)

    Mun, Hyeona; Choi, Soon-Mok; Lee, Kyu Hyoung; Kim, Sung Wng

    2015-07-20

    Thermoelectrics, which transports heat for refrigeration or converts heat into electricity directly, is a key technology for renewable energy harvesting and solid-state refrigeration. Despite its importance, the widespread use of thermoelectric devices is constrained because of the low efficiency of thermoelectric bulk alloys. However, boundary engineering has been demonstrated as one of the most effective ways to enhance the thermoelectric performance of conventional thermoelectric materials such as Bi2 Te3 , PbTe, and SiGe alloys because their thermal and electronic transport properties can be manipulated separately by this approach. We review our recent progress on the enhancement of the thermoelectric figure of merit through boundary engineering together with the processing technologies for boundary engineering developed most recently using Bi2 Te3 -based bulk alloys. A brief discussion of the principles and current status of boundary-engineered bulk alloys for the enhancement of the thermoelectric figure of merit is presented. We focus mainly on (1) the reduction of the thermal conductivity by grain boundary engineering and (2) the reduction of thermal conductivity without deterioration of the electrical conductivity by phase boundary engineering. We also discuss the next potential approach using two boundary engineering strategies for a breakthrough in the area of bulk thermoelectric alloys.

  15. 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.

  16. 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)

  17. Evolution of precipitate in nickel-base alloy 718 irradiated with argon ions at elevated temperature

    Science.gov (United States)

    Jin, Shuoxue; Luo, Fengfeng; Ma, Shuli; Chen, Jihong; Li, Tiecheng; Tang, Rui; Guo, Liping

    2013-07-01

    Alloy 718 is a nickel-base superalloy whose strength derives from γ'(Ni3(Al,Ti)) and γ″(Ni3Nb) precipitates. The evolution of the precipitates in alloy 718 irradiated with argon ions at elevated temperature were examined via transmission electron microscopy. Selected-area electron diffraction indicated superlattice spots disappeared after argon ion irradiation, which showing that the ordered structure of the γ' and γ″ precipitates became disordered. The size of the precipitates became smaller with the irradiation dose increasing at 290 °C.

  18. 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.

  19. 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...

  20. 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)

  1. Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

    DEFF Research Database (Denmark)

    Cecchetto, L; Ambat, Rajan; Davenport, A.J.;

    2007-01-01

    AA5182 aluminium alloy cold rolled samples were coated by thin Wlms of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very eVective for corrosion protection of aluminium alloys in neutral environment. This study underlines......: • a weak redox activity of the polymer which passivate the metal, • a proton involving self-healing process taking place at the polymer–metal interface, which contributes to delay local acidiWcation in Wrst steps of corrosion on EB coated aluminium surfaces....

  2. 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.

  3. 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.

  4. Nitridation of Ni-based alloys: thermodynamics, kinetics, and deformation phenomena accompanying internal precipitation

    Institute of Scientific and Technical Information of China (English)

    Alexander A. Kodentsov; Jorma K. Kivilahti; Frans J.J. van Loo

    2006-01-01

    When a moderately stable phase is precipitated out during an internal reaction, the behaviour of the penetrating atoms within the diffusion zone can be interpreted based on thermodynamic considerations. Evidence for "up-hill" diffusion of the penetrating species through the matrix towards the precipitation front during the internal nitridation of Ni-Cr alloys at 1125℃ and 6000 bar of N2-pressure was predicted. Such behaviour of nitrogen is opposite to the boundary conditions in Wagner's description of internal reactions. A volume change associated with the precipitation reaction resulted in a stress gradient between the alloys surface and the internal nitridation front. Stress relief occurred mainly by transport of nickel to the gas/metal interface. Pipe diffusion-controlled creep is the dominant stress accommodation mechanism during nitriding of dilute Ni-Cr alloys at 700℃ under a flowing NH3 + H2 gas mixture.

  5. 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.

  6. 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.

  7. Structural and Magnetic Studies in Ni-Mn-Ga based Ferromagnetic Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    R. P. Mathur

    2011-04-01

    Full Text Available Quaternary Ni50FexMn30-xGa20 (x = 2.5, 5, and 15 and Ni45Fe5Mn30Ga20 alloys based on modification of ferromagnetic shape memory alloy ternary Ni50Mn30Ga20 composition prepared by vacuum arc melting and subsequent heat-treatment were investigated to understand the effect of varying Fe-content in Ni-Fe-Mn-Ga alloys. With increasing Fe-content, saturation magnetisation and Curie temperature increased, however martensite transformation temperature did not show a systematic variation. The 57Fe Mossbauer spectra showed three distinct sub-spectra depending upon the site occupancy by Fe-atoms. The results are explained with site selection by Fe-atom in parent L21 lattice.Defence Science Journal, 2011, 61(3, pp.275-284, DOI:http://dx.doi.org/10.14429/dsj.61.645

  8. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys.

    Science.gov (United States)

    Chen, Bo; Xia, Gang; Cao, Xin-Ming; Wang, Jue; Xu, Bi-Yao; Huang, Pu; Chen, Yue; Jiang, Qing-Wu

    2013-03-01

    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 dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  9. 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.

  10. 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.

  11. Performance Comparison of Steam-Based and Chromate Conversion Coatings on Aluminum Alloy 6060

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    In this study, oxide layers generated on aluminum alloy 6060(UNS A96060) using a steam-based process were compared with conventional chromate and chromate-phosphate conversion coatings. Chemical composition and microstructure of the conversion coatings were investigated and their corrosion...

  12. 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

  13. 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

  14. 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.

  15. 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...

  16. 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.)

  17. 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.)

  18. 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.

  19. 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.

  20. 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.

  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. 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.)

  3. 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.)

  4. 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.

  5. Room temperature deformation of in-situ grown quasicrystals embedded in Al-based cast alloy

    Directory of Open Access Journals (Sweden)

    Boštjan Markoli

    2013-12-01

    Full Text Available An Al-based cast alloy containing Mn, Be and Cu has been chosen to investigate the room temperature deformation behavior of QC particles embedded in Al-matrix. Using LOM, SEM (equipped with EDS, conventional TEM with SAED and controlled tensile and compression tests, the deformation response of AlMn2Be2Cu2 cast alloy at room temperature has been examined. Alloy consisted of Al-based matrix, primary particles and eutectic icosahedral quasicrystalline (QC i-phase and traces of Θ-Al2Cu and Al10Mn3. Tensile and compression specimens were used for evaluation of mechanical response and behavior of QC i-phase articles embedded in Al-cast alloy. It has been established that embedded QC i-phase particles undergo plastic deformation along with the Al-based matrix even under severe deformation and have the response resembling that of the metallic materials by formation of typical cup-and-cone feature prior to failure. So, we can conclude that QC i-phase has the ability to undergo plastic deformation along with the Al-matrix to greater extent contrary to e.g. intermetallics such as Θ-Al2Cu for instance.

  6. High-frequency magnetic characteristics of Fe-Co-based nanocrystalline alloy films

    Institute of Scientific and Technical Information of China (English)

    HIHARA; Takehiko; SUMIYAMA; Kenji

    2010-01-01

    Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique.Their structural,static magnetic properties and high-frequency magnetic characteristics were investigated.In the energetic cluster deposition method,by applying a high-bias voltage to a substrate,positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source,to form a high-density Fe-Co alloy cluster-assembled film with good high-frequency magnetic characteristics.In the conventional magnetron sputtering method,only by rotating substrate holder and without applying a static inducing magnetic field on the substrates,we produced Fe-Co-based nanocrystalline alloy films with a remarkable in-plane uniaxial magnetic anisotropy and a good soft magnetic property.The obtained Fe-Co-O,Fe-Co-Ti-N,and Fe-Co-Cr-N films all revealed a high real permeability exceeding 500 at a frequency up to 1.2 GHz.This makes Fe-Co-based nanocrystalline alloy films potential candidates as soft magnetic thin film materials for the high-frequency applications.

  7. Microstructures and mechanical properties of Al-Mg and Al-Zn-Mg based alloys containing minor scandium and zirconium

    Institute of Scientific and Technical Information of China (English)

    尹志民; 姜锋; 潘青林; 郭飞跃; 朱大鹏; 宋练鹏; 曾渝; 王涛

    2003-01-01

    A series of Al-Mg and Al-Zn-Mg based alloys with and without Sc, Zr were prepared by ingot metallurgy. The mechanical properties and microstructures of the studied alloys under different treatment conditions were studied. In addition, the existing form and acting mechanism of minor Sc and Zr in Al-Mg and Al-Zn-Mg based alloys were analyzed and discussed. The following conclusions can be drawn. First, adding of minor Sc and Zr to those alloys can increase the strength of Al-Mg and Al-Zn-Mg based alloys by 25%, while the ductility can remain in 15% and 8%, respectively. Second, in Al-Mg and Al-Zn-Mg based alloys, minor Sc and Zr mainly exist in two forms of aluminides containing Sc and Zr, one is Al3(Sc,Zr)I precipitated from the melt during solidification, the other is Al3(Sc,Zr)Ⅱ precipitated during homogenization. The former is the most effective grain refiner for α(Al) solid solution matrix, and the latter is coherent with the matrix and can strongly pin dislocations and subboundaries, which can effectively restrain recrystallization of the alloys during hot deformation, annealing and solid solution. Third, strengthening caused by adding minor Sc and Zr to the studied alloys is mainly due to fine-grain strengthening, precipitation strengthening and substructure strengthening of Al3(Sc, Zr) caused by restraining recrystallization.

  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. 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

  10. 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.

  11. 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...

  12. 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... chloride from China. SUMMARY: The Commission hereby gives notice that it will proceed with a full...

  13. 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:...

  14. Environment-assisted cracking and hot cracking of Ni-base alloy dissimilar metal welds

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, P.; Toivonen, A.; Ehrnsten, U. (VTT Technical Research Centre of Finland, Espoo (Finland)); Haenninen, H.; Brederholm, A. (Aalto Univ. School of Science and Engineering, Faculty of Engineering and Architecture, Espoo (Finland))

    2010-05-15

    Environment-assisted cracking (EAC) susceptibility of dissimilar metal mock-up welds of Alloy 182 and 82 as well as Alloy 152 and 52 were studied with four-point bending specimens in steam doped with hydrogen, chloride, sulfate and fluoride at 400 deg C. The doped steam environment accelerated the crack initiation process and the susceptibility of the studied weld metals to EAC was obtained and ranked. High susceptibility to crack initiation and growth was observed with Alloy 182 and 82 weld metals, while Alloy 152 and 52 weld metals showed high resistance to crack initiation. No extension of the hot cracks was observed in the doped steam test in any of the studied materials. Fractography of the broken Alloy 182 and 82 samples showed both nickel deposition and presence of NiO in addition to the continuous spinel type Cr-rich oxide film on the fracture surface inside the crack. Fracture path was intergranular in all the studied samples. The same dissimilar metal welds were exposed to Varestraint hot cracking tests and their hot cracking susceptibility was also ranked and determined as a function of the amount of strain. The microstructures of the weld metals were fully characterized by optical metallography and a modern FE-SEM/EDS system. Hot cracking susceptibility was related to the solidification mechanism and segregation of Nb, Si, P and Mn in the weld metals. Fractography of the EAC and hot cracks was compared and their characteristic features are demonstrated. Finally, the mechanisms of hot cracking and EAC of nickel-base alloy dissimilar metal welds are identified and discussed. (orig.)

  15. 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)

  16. 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

  17. Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Klein

    2016-09-01

    Full Text Available Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

  18. 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.

  19. 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.

  20. 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.)

  1. 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

  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. The electronic mechanism of the gamma/gamma' interface strength of Ir-based alloys

    CERN Document Server

    Chen, K; Tse, J S

    2002-01-01

    The electronic structures of the gamma/gamma' interface for two-phase Ir-based alloys (Ir/Ir sub 3 Ta and Ir/Ir sub 3 Ti) 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 gamma/gamma' interface for the Ir/Ir sub 3 Ta alloy increase. The cohesive strength of the interface for the Ir/Ir sub 3 Ti alloy increases, whereas the shear strength of the interface for Ir/Ir sub 3 Ti decreases. The electron charge density, the Hirshfeld charge, and orbital charge transfers are also calculated and analysed. An electronic mechanism for the gamma/gamma' interface strength of Ir-based alloys is then suggested.

  4. 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.

  5. Thermal cooling effects in the microstructure and properties of cast cobalt-base biomedical alloys

    Science.gov (United States)

    Vega Valer, Vladimir

    Joint replacement prosthesis is widely used in the biomedical field to provide a solution for dysfunctional human body joints. The demand for orthopedic knee and hip implants motivate scientists and manufacturers to develop novel materials or to increase the life of service and efficiency of current materials. Cobalt-base alloys have been investigated by various researchers for biomedical implantations. When these alloys contain Chromium, Molybdenum, and Carbon, they exhibit good tribological and mechanical properties, as well as excellent biocompatibility and corrosion resistance. In this study, the microstructure of cast Co-Cr-Mo-C alloy is purposely modified by inducing rapid solidification through fusion welding processes and solution annealing heat treatment (quenched in water at room temperature. In particular the effect of high cooling rates on the athermal phase transformation FCC(gamma)↔HCP(epsilon) on the alloy hardness and corrosion resistance is investigated. The Co-alloy microstructures were characterized using metallography and microscopy techniques. It was found that the as cast sample typically dendritic with dendritic grain sizes of approximately 150 microm and containing Cr-rich coarse carbide precipitates along the interdendritic boundaries. Solution annealing gives rise to a refined microstructure with grain size of 30 microm, common among Co-Cr-Mo alloys after heat treating. Alternatively, an ultrafine grain structure (between 2 and 10 microm) was developed in the fusion zone for specimens melted using Laser and TIG welding methods. When laser surface modification treatments were implemented, the developed solidification microstructure shifted from dendritic to a fine cellular morphology, with possible nanoscale carbide precipitates along the cellular boundaries. In turn, the solidified regions exhibited high hardness values (461.5HV), which exceeds by almost 110 points from the alloy in the as-cast condition. The amount of developed athermal

  6. Glass forming ability of Zr-and Fe-based alloys at quenching from melts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The master alloy ingots(MAI)with the nominal composition Zr52.5 Ti5Cu17.9 Ni14.6Al10 and Fe61Co7Zr10Mo5W2B15(at%)were prepared by arc-melting in Ti-gettered Ar atmosphere.The Zr-based buttons of 6 mm and 9 mm in diameter were fully amorphous,but those of 13 mm in diameter experienced crystallization.The glass forming ability(GFA)of Fe-based alloys was relatively lower,and the buttons obtained were fully crystallized.The microhardness of the Zr-based buttons was about 500(Hv),and the Fe-based rod obtained by injection technique exhibited a high Vickers hardness of 1329.In addition,an amorphous-crystalline transition layers were observed in both the buttons and the rods.

  7. 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.

  8. 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

  9. 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.)

  10. 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

  11. Occupational doses in pediatric barium meal procedures

    International Nuclear Information System (INIS)

    Ionizing radiation has become an indispensable tool when it comes to diagnosis and therapy. However, its use should happen in a rational manner, taking into account the risks to which the staff is being exposed. Barium meal (BM), or upper gastrointestinal (GI) studies, using fluoroscopy, are widely used for gastroesophageal reflux disease diagnostic in children and professionals are required to stay inside the examination room to position and immobilize pediatric patients during the procedure. Therefore, it is very important that proffessionals strictly follow the technical standards of radiation protection. According to the ICRP and the NCRP recommendations, the annual limit equivalent doses for eyes, thyroid and hands are, espectively, 20 mSv, 150 mSv and 500 mSv. Based on those data, the aim of the current study is to estimate the annual equivalent dose for eyes, thyroid and hands of professionals who perform BM procedures in children. This was done using properly package LiF:Mg,Cu,P thermoluminescent dosimeters in 37 procedures; 2 pairs were positioned near each staff´s eye, 2 pairs on each professional´s neck (on and under the lead protector) and 2 pairs on both staff´s hands. The range of the estimative annual equivalent doses, for eyes, thyroid and hands, are, respectively: 14 – 36 mSv, 7 – 22 mSv and 14 – 58 mSv. Only the closest staff to the patient exceeded the annual equivalent doses in the eyes (around 80% higher than the limit set by ICRP). However, the results from this study, for hands and thyroid, compared to similar studies, show higher values. Therefore, the optimization implementation is necessary, so that the radiation levels can be reduced. (authors)

  12. 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.

  13. Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

    Science.gov (United States)

    Doi, H; Harrori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

    2001-02-01

    The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases.

  14. 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)

  15. 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)

  16. 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.

  17. 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.

  18. Comparison of Crevice Corrosion of Fe-Based Amorphous Metal and Crystalline Ni-Cr-Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shan, X; Ha, H; Payer, J H

    2008-07-24

    The crevice corrosion behaviors of an Fe-based bulk metallic glass alloy (SAM1651) and a Ni-Cr-Mo crystalline alloy (C-22) were studied in 4M NaCl at 100 C with cyclic potentiodynamic polarization and constant potential tests. The corrosion damage morphologies, corrosion products and the compositions of corroded surfaces of these two alloys were studied with optical 3D reconstruction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES). It was found that the Fe-based bulk metallic glass (amorphous alloy) SAM1651 had a more positive breakdown potential and repassivation potential than crystalline alloy C-22 in cyclic potentiodynamic polarization tests and required a more positive oxidizing potential to initiate crevice corrosion in constant potential test. Once crevice corrosion initiated, the corrosion propagation of C-22 was more localized near the crevice border compared to SAM1651, and SAM1651 repassivated more readily than C-22. The EDS results indicated that the corrosion products of both alloys contained high amount of O and were enriched in Mo and Cr. The AES results indicated that a Cr-rich oxide passive film was formed on the surfaces of both alloys, and both alloys were corroded congruently.

  19. Effects of Ti and Zr Substituted on the Electrochemical Characteristics of MgNi-Based Alloy Electrodes

    Institute of Scientific and Technical Information of China (English)

    FENG Yan; JIAO Li-Fang; YUAN Hua-Tang; ZHAO Ming

    2007-01-01

    Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni, and Mg0.9Ti0.06Zr0.04Ni were successfully prepared by means of mechanical alloying (MA). The structure and the electrochemical characteristics of these Mg-based materials were studied. The X-ray diffraction (XRD) result shows that the main phases of the alloys exhibit amorphous structure. The scanning electron microscopy (SEM) photograph shows that the particle size of Ti and Zr substituted alloys was about 2-4 μm in diameter. The cycle lives of the alloys were prolonged by adding Ti and Zr. After 50charge-discharge cycles, the discharge capacity of Mg0.9Ti0.06Zr0.04Ni was 91.74% higher than that of MgNi alloy and 37.96% higher than that of Mg0.9Ti0.1Ni alloy. The main reason for the electrode capacity decay is the formation of Mg(OH)2 (product of Mg corrosion) at the surface of alloy. The potentiodynamic polarization result indicates that Ti and Zr doping improves the anticorrosion in an alkaline solution. The electrochemical impedance spectroscopy (EIS) results suggest that proper amount of Ti and Zr doping improves the electrochemical catalytic activity significantly.

  20. Effect of hydrogen storage alloy on combustion properties of ammonium perchlorate /glycidylazide polymer -based propellant

    Science.gov (United States)

    Li, G. P.; Dou, Y. M.; Chai, C. P.; Luo, Y. J.

    2015-12-01

    Hydrogen storage alloys can serve as good potential fuels for propellant design, by improving the energy and combustion properties. The influence of hydrogen storage alloy (A30) on the combustion properties of ammonium perchlorate/glycidylazide polymer (AP/GAP)-based on propellant were studied. The results showed that A30 could increase the burning rate of propellants by 29.75% and 74.78%, compared with B30 and Al. The combustion model of AP/GAP-based propellant containing different fuel was built. Firstly, A30 reduced the high decomposition temperature and promote condensed phase reaction heat of AP. Secondly, A30 deduced the burning surface temperature. Thirdly, A30 might prove the explosive heat of propellant. Therefore, A30 could greatly improve combustion properties of AP/GAP-based propellant.

  1. 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

  2. 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)

  3. 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.

  4. 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.

  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. 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.)

  7. 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.

  8. 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.

  9. 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.

  10. Atom probe tomography of Ni-base superalloys Allvac 718Plus and Alloy 718.

    Science.gov (United States)

    Viskari, L; Stiller, K

    2011-05-01

    Atom probe tomography (APT) allows near atomic scale compositional- and morphological studies of, e.g. matrix, precipitates and interfaces in a wide range of materials. In this work two Ni-base superalloys with similar compositions, Alloy 718 and its derivative Allvac 718Plus, are subject for investigation with special emphasis on the latter alloy. The structural and chemical nuances of these alloys are important for their properties. Of special interest are grain boundaries as their structure and chemistry are important for the materials' ability to resist rapid environmentally induced crack propagation. APT has proved to be suitable for analyses of these types of alloys using voltage pulsed APT. However, for investigations of specimens containing grain boundaries and other interfaces the risk for early specimen fracture is high. Analyses using laser pulsing impose lower electrical field on the specimen thereby significantly increasing the success rate of investigations. Here, the effect of laser pulsing was studied and the derived appropriate acquisition parameters were then applied for microstructural studies, from which initial results are shown. Furthermore, the influence of the higher evaporation field experienced by the hardening γ' Ni(3)(Al,Nb) precipitates on the obtained results is discussed.

  11. 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.)

  12. Tribological properties of Al 7075 alloy based composites strengthened with Al2O3 fibres

    Directory of Open Access Journals (Sweden)

    K. Naplocha

    2011-04-01

    Full Text Available Wear resistance of 7075 aluminium alloy based composite materials reinforced with Al2O3 Saffil fibres was investigated. The measurementsof wear were performed applying the pin-on-disc method at dry friction conditions with the gray iron counterpart. The effects ofpressure of composite samples on the counterpart made of gray iron and the orientation of fibers in relation to the friction surface on wear rate were determined. The materials were produced by squeeze casting method where 80-90% porous ceramic preform were infiltrated.After T6 heat treatment hardness increased about 50-60% both for unreinforced alloy and composites containing strengthening Saffilfibres. Wear resistance of composite materials in relation to the unreinforced 7075 alloy was slightly worse at lower pressure of 0.8 MPa. Under higher pressure of 1.2 MPa wear resistance of unreinforced 7075 alloy was even better whereas no effect of orientation of fibers on wear in composite materials was observed. Additionally, significant wear of counterface in the presence of debris with fragmented Al2O3 fibres as abrasives was observed. Wear resistance improvement of composite materials was obtained when with alumina Saffil fibres Carbon C fibres in the preforms were applied.

  13. High temperature stability of Cr-carbides in an experimental Co-Re-based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mukherji, Debashis; Klauke, Michael; Roesler, Joachim [Technische Universitaet Braunschweig (Germany). Institut fuer Werkstoffe; Strunz, Pavel [Nuclear Physics Institute and Research Center Rez (Czech Republic); Zizak, Ivo [Berliner Elektronenspeicherring-Gesellschaft fuer Synchrotronstrahlung, Berlin (Germany); Schumacher, Gerhard; Wiedenmann, Albrecht [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany)

    2010-03-15

    The stability of the microstructure at high temperatures was studied in an experimental Co-Re-based alloy. The experimental alloy is mainly strengthened by Cr-carbides, particularly by those in the form of thin lamellar plates. Electron microscopic investigation on samples exposed for up to 1000 h to temperatures of 1000 and 1200 C showed that Cr{sub 23}C{sub 6} type carbides present in the alloy in different morphologies are unstable at these temperatures. It was also observed that the alloy hardness dropped after exposing the samples to elevated temperatures and much of this loss occurred within the first 100 h. In-situ diffraction measurements with synchrotron radiation showed that carbide dissolution started as early as 3 h of holding at 1000 C. Moreover, in-situ small angle neutron scattering results indicated that the carbides at the grain boundaries and the blocky carbides dissolve first and then the thin lamellar carbides. Further, the enrichment of Cr in the Co-matrix phase, which took place due to the dissolution of Cr-carbides, stabilized a Cr-Re-rich {sigma} phase. Although the dissolution of lamellar carbides results in a significant loss of strength, the formation of {sigma} phase with extremely high hardness partly compensated the for loss. The {sigma} phase is stable even at 1200 C. (orig.)

  14. 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.

  15. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    Institute of Scientific and Technical Information of China (English)

    Rui-ze Wang; Zhang-hua Chen; Yu-jie Li; Chao-fang Dong

    2013-01-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill’s quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at diff erent temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at diff erent temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal eff ects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at diff erent stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  16. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    Science.gov (United States)

    Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang

    2013-12-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  17. 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

  18. 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.

  19. 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

  20. Chemical composition of nanomodified composite binder with nano- and microsized barium silicate

    Directory of Open Access Journals (Sweden)

    KOROLEV Evgenij Valerjevich

    2014-08-01

    Full Text Available There are several possibilities to improve cement-based binders. In particular, many properties of cement stone can be enhanced by means of micro- and nanoscale modification. In a number of previous works we had shown that application of barium hydrosilicates leads to such improvement. The present article is devoted to the investigation of the chemical composition of the cement stone which is modified by means of addition of barium hydrosilicates. The modification was performed on different scales: micro- and nanoscale; the results of simultaneous multi-scale modification are also presented. The examination was carried out with help of different modern research techniques – FT IR spectroscopy, differential thermal analysis and X-ray phase analysis. Identification of the new phases and comparative quantitative assessment of their content are performed. It is found that the use of nano- and micro-sized barium hydrosilicates as additives leads to reduction of portlandite by 27...28%; by means of multi-scale modification it is possible to reduce the content of portlandite much more (by 83.3%. Due to addition of nano- and micro-sized barium-based modifiers both the amount of calcium hydrosilicates in reaction products is enlarged, and structure of the mentioned hydrosilicates is changed (the formation of a fine-grained structure of hydration products takes place. Micro-sized barium hydrosilicates are chemically active additives and promote the formation of an additional quantity of calcium hydrosilicates of type CSH (I. The use of nanoscale barium hydrosilicates promotes the formation of CSH (I and CSH (II calcium hydrosilicates, and also both riversidite and xonotlite. As a result of simultaneous application of nano- and micro-sized barium hydrosilicates the content of CSH (II increases. This can be confirmed by means of differential thermal and X-ray analysis. The amount of CSH (I, riversidite and various tobermorites is also increases. It is

  1. TENSILE STRENGTH AND CREEP RESISTANCE OF Mg-9Al-1ZnBASED ALLOYS WITH CALCIUM ADDITION

    Institute of Scientific and Technical Information of China (English)

    Y.S. Sun; W.M. Zhang; X.G. Min

    2001-01-01

    Small amount of calcium addition to the Mg-9Al-0. 8Zn-0.2Mn(AZ91) alloy resulted in the obvious influence on mechanical properties. The yield strength of the alloys increased with the increase of Ca addition and maximum strength was obtained from the alloy containing 0.15% of Ca. The creep resistance at the temperatures between 150-200°C was also significantly increased with Ca addition. The creep rate (at 200°C,50MPa) of the alloy with 0. 15% of Ca addition was one order of magnitude lower than that of the base alloy (AZ91). Microstructural observations revealed that the addition of calcium refined the microstructure and enhanced the thermal stability of the β precipitates, which accounted for the improvement of creep resistance at high temperatures.``

  2. 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.

  3. Preparation of TiFe based alloys melted by CaO crucible and its hydrogen storage properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chong-he, E-mail: chli@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); He, Jin; Zhang, Zhao; Yang, Bo; Leng, Hai-yan [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang, E-mail: luxg@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Li, Zhi-lin; Wu, Zhu [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Hong-bin [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

    2015-01-05

    Highlights: • The home-made CaO crucible was used to prepare the TiFe based alloys. • The compositions as well as the content of oxygen can be effectively controlled. • The microstructure of the alloy melted by CaO crucible is dendrite. • The samples performed a good hydrogen storage performance. • The CaO crucible may be the promising candidate for melting the TiFe based alloys. - Abstract: The carbon contamination of alloys prepared by the electro graphite crucible is impossible to avoid due to the inherit reaction between the melt and the crucible. In this study, the TiFe-based alloy is prepared by VIM process using CaO crucible as well as the electro graphite crucible. The samples are examined by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS), and the PCT curves are also measured. It is resulted that, the oxygen content of alloys melted by CaO crucible is almost equal to the one melted by graphite crucible and without the carbon contamination, meanwhile the carbon content of alloys obtained by the electro graphite crucible is 1860 ppm, which exceeds the tolerance of the commercial alloy (1000 ppm). The microstructure of the alloy melted by CaO crucible is dendrite, while it is composed of the equiaxed crystal with the lamellar structure and the spherical TiC particles distributed along grain boundaries or within the grain when melted by the graphite crucible; the interfacial reaction of the electro graphite crucible with TiFe alloy melt is serious and the interaction layer is formed up to 200 μm in thickness, the carbon in TiFe-based alloys forms TiC. The hydrogen desorption plateau pressure of alloys melted by CaO crucible is (0.11–0.4) × 10{sup 5} Pa, and that by the graphite crucible is (0.6–1) × 10{sup 5} Pa. This may imply that the CaO crucible may be the promising candidate for melting the high performance TiFe based hydrogen storage alloys.

  4. 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

  5. Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

    Science.gov (United States)

    Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

    2016-04-27

    Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

  6. Multi-scale Modelling of bcc-Fe Based Alloys for Nuclear Applications

    International Nuclear Information System (INIS)

    , advanced techniques to fit interatomic potentials consistent with thermodynamics are proposed and the results of their application to the mentioned alloys are presented. Next, the development of advanced methods, based on the use of artificial intelligence, to improve both the physical reliability and the computational efficiency of kinetic Monte Carlo codes for the study of point-defect clustering and phase changes beyond the scale of MD, is reported. These recent progresses bear the promise of being able, in the near future, of producing reliable tools for the description of the microstructure evolution of realistic model alloys under irradiation. (author)

  7. 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.

  8. 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.

  9. Microstructure of Ni-Based Self-Fluxing Alloy Sprayed Coating

    Institute of Scientific and Technical Information of China (English)

    WANG Jin-hua; Milan Friesel; Magnus Willander; Richard Warren

    2005-01-01

    The microstructure of Ni-based self-fluxing alloy thermal sprayed coating was investigated by microanal ysis methods.The sprayed coating was produced by the oxygen-acetylene gas flame spraying Ni-16.9Cr-3.5B4.5Si-4.6Fe-0.83C system alloy powder onto a common steel substrate.Different phases can be recognized from the morphology in the metallographic images and SEM images of compounds of high magnification.The TEM images of the (Cr,Fe,Ni) superlattice phase particles can be obtained in dark field,and the particle size is between 20 nm and 60 nm.The electron diffraction patterns of the superlattice phase and Ni-based solid solution phase can be found,as analyzed by the EDAX spectra chemical composition analysis method.

  10. 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.

  11. Variational prediction of the mechanical behavior of shape memory alloys based on thermal experiments

    Science.gov (United States)

    Junker, Philipp; Jaeger, Stefanie; Kastner, Oliver; Eggeler, Gunther; Hackl, Klaus

    2015-07-01

    In this work, we present simulations of shape memory alloys which serve as first examples demonstrating the predicting character of energy-based material models. We begin with a theoretical approach for the derivation of the caloric parts of the Helmholtz free energy. Afterwards, experimental results for DSC measurements are presented. Then, we recall a micromechanical model based on the principle of the minimum of the dissipation potential for the simulation of polycrystalline shape memory alloys. The previously determined caloric parts of the Helmholtz free energy close the set of model parameters without the need of parameter fitting. All quantities are derived directly from experiments. Finally, we compare finite element results for tension tests to experimental data and show that the model identified by thermal measurements can predict mechanically induced phase transformations and thus rationalize global material behavior without any further assumptions.

  12. 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.

  13. Glass-Forming Ability of an Iron-Based Alloy Enhanced by Co Addition and Evaluated by a New Criterion

    Institute of Scientific and Technical Information of China (English)

    CHEN Qing-Jun; SHEN Jun; FAN Hong-Bo; SUN Jian-Fei; HUANG Yong-Jiang; MCCARTNEY D. G.

    2005-01-01

    @@ A new Fe-based alloy that can be cast into a fully amorphous rod with a diameter of at least 16mm by the conventional copper-mould casting technique is obtained by partially replacing Fe with Co in a previously reported Fe-based bulk metallic glass. The preliminary thermodynamic analysis indicates that the Co-containing alloy has a significantly lower Gibbs free energy difference between the undercooled melt and the corresponding crystalline solid, compared to the Co-free alloy, reflecting the dramatic role of the Co addition in stabilizing the supercooled melt and facilitating glass formation in iron-based alloys. Here, a new criterion, derived from the classical nucleation and growth theory, is introduced to evaluate the glass-forming ability of Fe-based bulk metallic glasses.

  14. Correlation between superheated liquid fragility and potential energy landscape in Gd-and Pr-based glass-forming alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The kinetic viscosities of superheated liquids on the Gd-based bulk glass-forming alloys are measured by an oscillating viscometer in a high vacuum atmosphere. According to the viscosity data,the parameters of superheated liquid fragility,M,are calculated. Based on the values of M in Gd-and Pr-based (cited from the lit-erature) glass-forming alloys,we find that there is a linear correlation between M and the absolute value of mixing enthalpy,|ΔHmix|,in an alloy system with the same base element,and the larger M,the smaller |ΔHmix|. The alloy with larger M exhibits the larger height of energy barriers separating the minima on the potential energy landscape.

  15. Preparation and study of properties of SmS base alloys

    International Nuclear Information System (INIS)

    By reducing sesquisulphides of Sm and Yb with a metallic rare-earth element (Yb, Sm, Eu), monosulphides of these elements and solid solutions on their basis have been obtained. By varying the content in SmS of the other rare-earth element (Yb or Eu), it is possible to effectively control the electrophysical properties (electric conductivity, heat conductivity) of alloys based on it by changing the energetic position of f-states, their energy density and their population with electrons

  16. Effects of Rare Earths on Properties of Ti-Zr-Cu-Ni Base Brazing Filler Alloys

    Institute of Scientific and Technical Information of China (English)

    Ma Tianjun; Kang Hui; Wu Yongqin; Qu Ping

    2004-01-01

    The effects of the addition of rare earths on the properties of Ti-Zr-Cu-Ni base brazing filler alloys and the mechanical microstructure and properties were studied for the brazed-joints in the vacuum brazing of TC4 by comparing synthetical properties of two kinds of filler metals.The results indicate that the filler metals added with rare earths have lower melting point, better wettability and higher mechanical properties in the brazing joints.

  17. Fe0-based alloys for Environmental Remediation: Thinking outside the Box

    OpenAIRE

    NOUBACTEP, C.; Schöner, A.

    2008-01-01

    A review of the approach used by environmental remediation researchers to evaluate the reactivity of Fe-0-based alloys reveals the lack of consideration of the results available from other branches of science. This paper discusses the limitations of the current approach. The discussion provided here suggests that the current assumption that redox-sensitive species serve as corrosive agents for Fen maybe incorrect because water as the solvent is also corrosive. A new approach is proposed in wh...

  18. Simulation and experiments of ultrasonic propagation in nickel-based alloy weldments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to obtain good understanding of complicated beam propagation behaviors in nickel-based alloy weldments, ray tracing simulation is established to predict the ultrasonic beam path in a special welded structure of dissimilar steels. Also experimental examinations are carried out to measure the ultrasonic beam paths in the weldment. Then comparisons of the modeling predictions with experimental results are presented to reveal the complicated beam propagation behaviors.

  19. Corrosion behavior of iron and nickel base alloys under solid oxide fuel cell exposure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.

    2006-03-01

    Topography and phase composition of the scales formed on commercial ferritic stainless steels and experimental low CTE nickel-based alloys were studied in atmospheres simulating solid oxide fuel cell (SOFC) environments. The materials were studied under dual environment conditions with air on one side of the sample and carbon monoxide on the other side at 750°C. Surface characterization techniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.

  20. Interdiffusion behavior of Pt-modified γ-Ni + γ'-Ni3Al alloys coupled to Ni-Al-based alloys

    Science.gov (United States)

    Hayashi, Shigenari; Wang, Wen; Sordelet, Daniel J.; Gleeson, Brian

    2005-07-01

    The effect of platinum addition on the interdiffusion behavior of γ-Ni + γ'-Ni3Al alloys was studied by using diffusion couples comprised of a Ni-Al-Pt alloy mated to a Ni-Al, Ni-Al-Cr, or Ni-based commercial alloy. The commercial alloys studied were CMSX-4 and CMSX-10. Diffusion annealing was at 1150 °C for up to 100 hours. An Al-enriched γ'-layer often formed in the interdiffusion zone of a given couple during diffusion annealing due to the uphill diffusion of Al. This uphill diffusion was ascribed to Pt addition decreasing the chemical activity of aluminum in the γ + γ' alloys. For a given diffusion couple end member, the thickening kinetics of the γ' layer that formed increased with increasing Pt content in the Ni-Al-Pt γ + γ' alloy. The γ'-layer thickening kinetics in diffusion couples with Cr showed less of a dependence on Pt concentration. Inference of a negative effect of Pt and positive effect of Cr on the Al diffusion in this system enabled explanation of the observed interdiffusion behaviors. There was no or minimal formation of detrimental topologically close-packed (TCP) phases in the interdiffusion zone of the couples with CMSX-4 or CMSX-10. An overlay Pt-modified γ + γ' coating on CMSX-4 showed excellent oxidation resistance when exposed to air for 1000 hours at 1150 °C. Moreover, the Al content in the coating was maintained at a relatively high level due to Al replenishment from the CMSX-4 substrate.

  1. The impact of carbon on single crystal nickel-base superalloys: Carbide behavior and alloy performance

    Science.gov (United States)

    Wasson, Andrew Jay

    Advanced single crystal nickel-base superalloys are prone to the formation of casting grain defects, which hinders their practical implementation in large gas turbine components. Additions of carbon (C) have recently been identified as a means of reducing grain defects, but the full impact of C on single crystal superalloy behavior is not entirely understood. A study was conducted to determine the effects of C and other minor elemental additions on the behavior of CMSX-4, a commercially relevant 2nd generation single crystal superalloy. Baseline CMSX-4 and three alloy modifications (CMSX-4 + 0.05 wt. % C, CMSX-4 + 0.05 wt. % C and 68 ppm boron (B), and CMSX-4 + 0.05 wt. % C and 23 ppm nitrogen (N)) were heat treated before being tested in high temperature creep and high cycle fatigue (HCF). Select samples were subjected to long term thermal exposure (1000 °C/1000 hrs) to assess microstructural stability. The C modifications resulted in significant differences in microstructure and alloy performance as compared to the baseline. These variations were generally attributed to the behavior of carbide phases in the alloy modifications. The C modification and the C+B modification, which both exhibited script carbide networks, were 25% more effective than the C+N modification (small blocky carbides) and 10% more effective than the baseline at preventing grain defects in cast bars. All C-modified alloys exhibited reduced as-cast gamma/gamma' eutectic and increased casting porosity as compared to baseline CMSX-4. The higher levels of porosity (volume fractions 0.002 - 0.005 greater than the baseline) were attributed to carbides blocking molten fluid flow during the final stages of solidification. Although the minor additions resulted in reduced solidus temperature by up to 16 °C, all alloys were successfully heat treated without incipient melting by modifying commercial heat treatment schedules. In the B-containing alloy, heat treatment resulted in the transformation of

  2. Production of translationally cold barium monohalide ions

    OpenAIRE

    DePalatis, M. V.; Chapman, M.S.

    2013-01-01

    We have produced sympathetically cooled barium monohalide ions BaX$^+$ (X = F, Cl, Br) by reacting trapped, laser cooled Ba$^+$ ions with room temperature gas phase neutral halogen-containing molecules. Reaction rates for two of these (SF$_6$ and CH$_3$Cl) have been measured and are in agreement with classical models. BaX$^+$ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.

  3. Development of wear-resistant coatings for cobalt-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.

    1999-03-01

    The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified.

  4. A protective (Mo,W)(Si,Ge)2 coating on Nb-base alloys

    International Nuclear Information System (INIS)

    This paper reports on a multicomponent diffusion coating that has been developed to protect Nb-base alloys from high-temperature environmental attack. A solid solution of molybdenum and tungsten disilicide constituted the primary coating layer which supported a slow-growing protective silica scale in service. Germanium additions were made during the coating process to improved the cyclic oxidation resistance by increasing the thermal expansion coefficient of the silica scale formed, and, to avoid pesting by decreasing the viscosity of the protective vitreous film. The development of the halide-activated pack cementation coating process to produce the coating on Nb-base alloys is described. The results of cyclic oxidation for coupons coated under different conditions in air at 1370 degrees C are presented. Many coupons have successfully passed 200 one-hour cyclic oxidation tests at 1370 degrees C with weight gain values in the range of 1.2-1.6 mg/cm2. This multicomponent silicide coating offers significant promise to protect Nb-base alloys in oxidizing environments and thermal cycling at high temperatures

  5. Superplastic solid state welding steel and copper alloy based on laser quenching of steel surface

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ke-ke; HAN Cai-xia; QUAN Shu-li; CHENG Guang-hui; YANG Jie; YANG Yun-lin

    2005-01-01

    Based on the feasibility of isothermal superplastic solid state welding of steel and copper alloy, the welded surface of steel surface was ultra-fined through laser quenching, and then the welding process tests between different base metals of 40Cr and QCr0.5 were made under the condition of non vacuum and non shield gas. The experimental results show that, with the sample surface of steel after laser quenching and that of copper alloy carefully cleaned, and under the pre-pressed stress of 56.6 -84.9 MPa, at the welding temperature of 750 -800 ℃ and at initial strain rate of (2.5 - 7.5) × 10-4 s-1 , the solid state welding can be finished in 120 - 180 s so that the strength of the joint is up to that of QCr0.5 base metal and the expansion rate of the joint does not exceed 6%. The plastic deformation of the joint was further analysed. The superplastic deformation of the copper alloy occurs in welding process and the deformation of steel are little.

  6. A Comparison between Shear Bond Strength of VMK Master Porcelain with Three Base-metal Alloys (Ni-cr-T3, VeraBond, Super Cast) and One Noble Alloy (X-33) in Metal-ceramic Restorations

    OpenAIRE

    Dabaghi Tabriz F.; Epakchi S.; Mousavi N.; Neshati A.; Ahmadzadeh A.; Sarbazi AH.

    2013-01-01

    Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the commonly used VMK Master Porcelain. Materials and Method: Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, and VeraBond) and one group of noble a...

  7. Study of barium bismuth titanate prepared by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2009-01-01

    Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

  8. Microstructure of composite material with powders of barium ferrite

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2006-04-01

    Full Text Available Purpose: The aim of the present work is the microstructure characterization of commercial powder BaFe12O19 (as-prepared and composite material with BaFe12O19 powders and polymer matrix, using XRD (X-Ray Diffraction and SEM (Scanning Electron Microscopy methods.Design/methodology/approach: The morphology of barium ferrite powders and a fracture surface of the examined composite material was realized by using the scanning electron microscope. The methods of X-ray diffraction were used for the qualitative phase analysis. The parameters of diffraction line profiles were determined by PRO-FIT Toraya procedure.Findings: The X-ray diffraction analysis permitted on identification the BaFe12O19 and Fe2O3 phases in an examined material. Basing on Toraya method is determination of: lattice parameters, crystallite size (D and the lattice distortion (. Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles have irregular shapes and dimensions.Research limitations/implications: For future research the X-ray analysis should be performed by the Rietveld method, which allows to characterization the microstructure of tested material and verification of its qualitative phase composition.Originality/value: The applied Toraya method of structure analysis appeared to be very useful in the microstructure analysis.

  9. 钡离子对镍基钙钛矿分解氨的影响%Decomposition of ammonia by barium ions on the nickel-based perovskite

    Institute of Scientific and Technical Information of China (English)

    陈为强; 丁彤; 马智; 谢洪燕

    2015-01-01

    镍基钙钛矿分解氨制取氢气虽有稳定性好、价格低廉的优点,但也有完全分解温度偏高的缺点。为降低完全分解氨制取氢气的温度,实验采用柠檬酸络合法,通过改变A位掺杂离子与掺杂量对LaNiO3改性,并改变载体及负载量,制备一系列的催化剂。采用XRD、SEM、TEM表征技术进行表征,考察了Ba 含量对催化剂结构与性能的影响。实验表明在催化剂装填量为1mL、空速为10000h–1、原料气为纯氨的条件下,氨分解的最佳电子助剂离子为 Ba、最优催化剂为 w(NiO)=20%的 La0.9Ba0.1NiO3/MCM-41,氨气完全分解温度由650℃降为575℃。随着Ba掺杂量的增加,催化剂活性先增加,在x=0.1达到最大值,之后减小,掺杂Ba过多催化剂的结构由钙钛矿变为非钙钛矿,非钙钛矿结构的催化剂活性不如钙钛矿。%Nickel-based perovskite catalyst,for decomposing ammonia to produce hydrogen,has good stability and low cost,but also requires high decomposition temperature. In order to reduce the complete temperature decomposition of ammonia,experiments,using citrate method,by changing the A-site doping ions and doping amounts to modify LaNiO3,were conducted with changed carriers and load amounts to prepare a series of catalysts. With XRD,SEM,TEM characterization,the effects of Ba on the structure and properties of catalyst were studied. Under the conditions of catalyst loading amount of 1mL,space velocity of 10000h-1,and pure ammonia as feed gas,the best electronic aids ions of ammonia decomposition is Ba,the best catalyst isw(NiO) = 20% of La0.9Ba0.1NiO3/MCM-41,which can make the complete decomposition temperature decrease from 650℃ to 575℃. With the increase of Ba doping amount,catalyst activity first increased,reaches a maximum atx= 0.1,and then decreased. Due to too much Ba doping,the structure of the catalyst change from perovskite to non-perovskite. The catalyst activity of perovskite is

  10. Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

    International Nuclear Information System (INIS)

    Fe74Ni3Si13Cr6W4 amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 °C or more are composed of lots of ultra-fine α-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 °C, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 °C. Thus the powder samples annealed at 650 °C show optimal reflection loss under −10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T. - Highlights: ► The annealing temperature effect of Fe-based amorphous alloy was studied. ► Fe-based amorphous and nanocrystalline alloy has a good absorbing property in C-band. ► There exists a correspondence between microwave properties and microstructure.

  11. Heat treatment influence on corrosion resistance of Fe3Al intermetallic phase based alloy

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2006-08-01

    Full Text Available Purpose: In this paper attention was paid to determine the corrosion resistance of Fe3Al intermetallic phasebased alloy in corrosive medium of liquid hydrochloric acid with 0.2% concentration and sulphuric acid with 3%concentration. Research of material susceptibility to surface activation in the pipeline of corrosion processes areconducted. Work is continuation of earlier research of corrosion resistance evaluation tests for FeAl intermetallicphase based alloy in liquid HCl and H2SO4 corrosive medium.Design/methodology/approach: In the corrosion research electrolyser, potentiostat „Solartron 1285” andcomputer with „CorrWare 2” software were used. Results of the research were worked out with „CorrView”software. The potentials values were determined in relation to normal hydrogen electrode (NEW. Thetemperature of the solutions was kept on 21ºC level. The recording of potential/density of current - time curvewas conducted for 300 s.Findings: The results of research conducted in 0.2% HCl solution, the best electrochemical corrosion resistancewere showed by samples after annealing during 72 hours. It was confirmed by the lowest value of corrosioncurrent density, low value of passive current density, pitting corrosion resistance much higher than in othersamples.Practical implications: The last feature is the reason to conduct the research for this group of materials ascorrosion resistance materials. Especially FeAl and Fe3Al intermetallic phase based alloys are objects ofresearch in Poland and all world during last years.Originality/value: The goal of this work was to determine the influence of homogenizing treatment timeon corrosion resistance of Fe28Al intermetallic phase based alloy in 0.2% HCl and 3% H2SO4 solutions.Homogenizing treatment was conducted in temperature of 1050ºC during: 24, 48, 72 and 96 h.

  12. Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

    Energy Technology Data Exchange (ETDEWEB)

    He Jinghua; Wang Wei; Wang Aimin [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Guan Jianguo, E-mail: guanjg@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2012-09-15

    Fe{sub 74}Ni{sub 3}Si{sub 13}Cr{sub 6}W{sub 4} amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 Degree-Sign C or more are composed of lots of ultra-fine {alpha}-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 Degree-Sign C, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 Degree-Sign C. Thus the powder samples annealed at 650 Degree-Sign C show optimal reflection loss under -10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T. - Highlights: Black-Right-Pointing-Pointer The annealing temperature effect of Fe-based amorphous alloy was studied. Black-Right-Pointing-Pointer Fe-based amorphous and nanocrystalline alloy has a good absorbing property in C-band. Black-Right-Pointing-Pointer There exists a correspondence between microwave properties and microstructure.

  13. Spin Transfer Torque Switching and Perpendicular Magnetic Anisotropy in Full Heusler Alloy Co2FeAl-BASED Tunnel Junctions

    Science.gov (United States)

    Sukegawa, H.; Wen, Z. C.; Kasai, S.; Inomata, K.; Mitani, S.

    2014-12-01

    Some of Co-based full Heusler alloys have remarkable properties in spintronics, that is, high spin polarization of conduction electrons and low magnetic damping. Owing to these properties, magnetic tunnel junctions (MTJs) using Co-based full Heusler alloys are potentially of particular importance for spintronic application such as magnetoresistive random access memories (MRAMs). Recently, we have first demonstrated spin transfer torque (STT) switching and perpendicular magnetic anisotropy (PMA), which are required for developing high-density MRAMs, in full-Heusler Co2FeAl alloy-based MTJs. In this review, the main results of the experimental demonstrations are shown with referring to related issues, and the prospect of MTJs using Heusler alloys is also discussed.

  14. Effects of can parameters on canned-forging process of TiAl base alloy(Ⅱ)--Mechanical behavior

    Institute of Scientific and Technical Information of China (English)

    刘咏; 何双珍; 黄伯云; 韦伟峰; 贺跃辉; 周科朝

    2002-01-01

    By using thermal simulation technique and computer simulation, the conventional canned-forging process of TiAl base alloy was studied. The effect of can parame ters on the mechanical behavior of TiAl alloys with diffe rent H/D ratios was analyzed in this process. The results show that, the pea k stress of TiAl base alloy without canning is far higher than that with canning. Compared with the samples with the same H/D ratio, the peak stress decreases with increa sing can thickness; while compared with the samples with the same can thickness , the peak stress decreases with increasing H/D ratio. The decrease of t he true stress of TiAl base alloy with canning were analyzed according to the theory of plastic deformation and results of computer simulation.

  15. Effect of Rare Earth on Microstructure of Vacuum Melting Ni-Based Self-Fluxing Alloy Coatings

    Institute of Scientific and Technical Information of China (English)

    宣天鹏; 闵丹

    2004-01-01

    The Ni-based self-fluxing alloy coating containing RE was acquired by the technique of vacuum melting on the hypoeutectoid steel (Fe-0.45%C) matrix. By X-ray diffraction, SEM and EDX, the microstructure and phase structure of section of coating and the microstructure near the interface between coating and matrix were investigated, and the effect of RE on microstructure of coating was also discussed. The results show that the microstructure of the NiCrBSi alloy coating is composed of Ni-based solid solution and a lot of massive, globular and needle secondary phases CrB, Ni3B, Cr7C3, Cr23C6 among the solid solution. The metallurgical binding between steel matrix and coating is realized. RE makes needle phase of alloy coating vanish. New phases of NiB and Cr6.5Ni2.5Si are precipitated from alloy coating, and secondary phases of alloy coating are sphericized. Consequently, RE also hinders the diffusion of Ni, Cr and Si atoms from coating to matrix and Fe atoms from matrix to coating, holds back the dilution of Fe for NiCrBSi alloy coating, and assures the chemical composition of the alloy coating.

  16. Optimized constitutive equation of material property based on inverse modeling for aluminum alloy hydroforming simulation

    Institute of Scientific and Technical Information of China (English)

    LANG Li-hui; LI Tao; ZHOU Xian-bin; B. E. KRISTENSEN; J. DANCKERT; K. B. NIELSEN

    2006-01-01

    By using aluminum alloys, the properties of the material in sheet hydroforming were obtained based on the identification of parameters for constitutive models by inverse modeling in which the friction coefficients were also considered in 2D and 3D simulations. With consideration of identified simulation parameters by inverse modeling, some key process parameters including tool dimensions and pre-bulging on the forming processes in sheet hydroforming were investigated and optimized. Based on the optimized parameters, the sheet hydroforming process can be analyzed more accurately to improve the robust design. It proves that the results from simulation based on the identified parameters are in good agreement with those from experiments.

  17. Development of Forsterite Based Insulating Board for Alloy Steel Con—casting Tundish

    Institute of Scientific and Technical Information of China (English)

    ZHAOJi-zeng; ZHOULei; 等

    1994-01-01

    To meet the operation requirement of com-casting tundish for alloy steel.a forsterite based insulating board has been developed.The effects of binder ,fiber and other additives on the properties of the properties of the products have been described;the theoretial reason of assuring containing clear steel by using inorganic binder bonded forsterite based insulating board were also discussed;the mineral composition and microstructure of the products have been analyzed by means of XRD.SEM and microscope ,The results indicate that the forsteite based insulating board with excel-lent performance and dood application results has been obtained.

  18. The effect of nanobioceramic reinforcement on mechanical and biological properties of Co-base alloy/hydroxyapatite nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, M., E-mail: m.bahrami@ma.iut.ac.ir; Fathi, M.H.; Ahmadian, M.

    2015-03-01

    The goal of the present research was to fabricate, characterize, and evaluate mechanical and biological properties of Co-base alloy composites with different amounts of hydroxyapatite (HA) nanopowder reinforcement. The powder of Co–Cr–Mo alloy was mixed with different amounts of HA by ball milling and it was then cold pressed and sintered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used. Microhardness measurement and compressive tests were also carried out. Bioactivity behavior was evaluated in simulated body fluid (SBF). A significant decrease in modulus elasticity and an increase in microhardness of the sintered composites were observed. Apatite formation on the surface of the composites showed that it could successfully convert bioinert Co–Cr–Mo alloy to bioactive type by adding 10, 15, and 20 wt.% HA which have lower modulus elasticity and higher microhardness. - Graphical abstract: The present investigation has been based on the production of composite materials based on Co–Cr–Mo alloy with different amounts of hydroxyapatite nanobioceramic powder using the powder metallurgy route. Mechanical and biological properties of the composites were investigated. A significant increase in microhardness and decrease in modulus elasticity of the sintered composites were observed. - Highlights: • Co-base alloy/hydroxyapatite composites were prepared by powder metallurgy. • Composite microhardness is improved in comparison with Co-base alloy. • Modulus elasticity decrease by about 53–63% in comparison with Co-base alloy. • Apatite nucleus is formed on the surface of composites after soaking test. • Bioinert Co–Cr–Mo alloy is successfully converted to a bioactive type.

  19. The effect of nanobioceramic reinforcement on mechanical and biological properties of Co-base alloy/hydroxyapatite nanocomposite

    International Nuclear Information System (INIS)

    The goal of the present research was to fabricate, characterize, and evaluate mechanical and biological properties of Co-base alloy composites with different amounts of hydroxyapatite (HA) nanopowder reinforcement. The powder of Co–Cr–Mo alloy was mixed with different amounts of HA by ball milling and it was then cold pressed and sintered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used. Microhardness measurement and compressive tests were also carried out. Bioactivity behavior was evaluated in simulated body fluid (SBF). A significant decrease in modulus elasticity and an increase in microhardness of the sintered composites were observed. Apatite formation on the surface of the composites showed that it could successfully convert bioinert Co–Cr–Mo alloy to bioactive type by adding 10, 15, and 20 wt.% HA which have lower modulus elasticity and higher microhardness. - Graphical abstract: The present investigation has been based on the production of composite materials based on Co–Cr–Mo alloy with different amounts of hydroxyapatite nanobioceramic powder using the powder metallurgy route. Mechanical and biological properties of the composites were investigated. A significant increase in microhardness and decrease in modulus elasticity of the sintered composites were observed. - Highlights: • Co-base alloy/hydroxyapatite composites were prepared by powder metallurgy. • Composite microhardness is improved in comparison with Co-base alloy. • Modulus elasticity decrease by about 53–63% in comparison with Co-base alloy. • Apatite nucleus is formed on the surface of composites after soaking test. • Bioinert Co–Cr–Mo alloy is successfully converted to a bioactive type

  20. Role of samarium additions on the shape memory behavior of iron based alloys

    International Nuclear Information System (INIS)

    Research highlights: → The effect of samarium contents on shape memory behavior has been studied. → Addition of samarium increases the strength, c/a ratio and ε (hcp martensite). → Addition of samarium retards the nucleation of α (bcc martensite). → Improvement in shape memory effect with the increase in samarium contents. - Abstract: The effect of samarium contents on shape memory behavior of iron based shape memory alloys has been studied. It is found that the strength of the alloys increases with the increase in samarium contents. This effect can be attributed to the solid solution strengthening of austenite by samarium addition. It is also noticed that the shape memory effect increases with the increase in samarium contents. This improvement in shape memory effect presumably can be regarded as the effect of improvement in strength, increase in c/a ratio and obstruction of nucleation of α in the microstructure.

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

    Directory of Open Access Journals (Sweden)

    B.R.SRIDHAR,

    2011-01-01

    Full Text Available 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 subjected to different surface conditions such as emery polishing, shot peening to different intensities after emery polishing and thermal stress relief after shot peening. Surface residual stresses were measured by X ray Diffraction technique. Changes in the magnitude of residual stresscould be attributed to corresponding changes in surface conditions and the accompanying surface cold work.

  2. Laser multi-layer cladding on ZM6 magnesium base alloy

    Institute of Scientific and Technical Information of China (English)

    Changjun Chen(陈长军); Dongsheng Wang(王东生); Maocai Wang(王茂才)

    2003-01-01

    A pulsed Nd: YAG laser is used in multi-layer cladding on ZM6 Mg base alloys. The microstructure isstudied with an optical microscope and a scanning electron microscope (SEM). The composition within thelayer was determined by electron probe microanalysis (EPMA). X-ray diffraction (XRD) was also used toinvestigate the phase of constitutes of the cladding zone. The results show that microstructure in solidifiedcladding layer changes much when treated by high energy laser beam. The microstructure of the ZM6alloy consists of α-Mg and Mg9Nd, while the L-ZM6 of α-Mg, Mg9Nd and c-Zr. The depth of the claddingis over 1 mm. Many fine particles were found to be distributed homogeneously throughout the matrix andthe columnar grain grows along substrate.

  3. Observation of Pseudopartial Grain Boundary Wetting in the NdFeB-Based Alloy

    Science.gov (United States)

    Straumal, B. B.; Mazilkin, A. A.; Protasova, S. G.; Schütz, G.; Straumal, A. B.; Baretzky, B.

    2016-08-01

    The NdFeB-based alloys were invented in 1980s and remain the best-known hard magnetic alloys. In order to reach the optimum magnetic properties, the grains of hard magnetic Nd2Fe14B phase have to be isolated from one another by the (possibly thin) layers of a non-ferromagnetic Nd-rich phase. In this work, we observe that the few-nanometer-thin layers of the Nd-rich phase appear between Nd2Fe14B grains due to the pseudopartial grain boundary (GB) wetting. Namely, some Nd2Fe14B/Nd2Fe14B GBs are not completely wetted by the Nd-rich melt and have the high contact angle with the liquid phase and, nevertheless, contain the 2-4-nm-thin uniform Nd-rich layer.

  4. Identification of epsilon martensite in a Fe-based shape memory alloy by means of EBSD.

    Science.gov (United States)

    Verbeken, K; Van Caenegem, N; Raabe, D

    2009-01-01

    Ferrous shape memory alloys (SMAs) are often thought to become a new, important group of SMAs. The shape memory effect in these alloys is based on the reversible, stress-induced martensitic transformation of austenite to epsilon martensite. The identification and quantification of epsilon martensite is crucial when evaluating the shape memory behaviour of this material. Previous work displayed that promising results were obtained when studying the evolution of the amount of epsilon martensite after different processing steps with Electron BackScatter Diffraction (EBSD). The present work will discuss in detail, on the one hand, the challenges and opportunities arising during the identification of epsilon martensite by means of EBSD and, on the other hand, the possible interpretations that might be given to these findings. It will be illustrated that although the specific nature of the austenite to epsilon martensite transformation can still cause some points of discussion, EBSD has a high potential for identifying epsilon martensite.

  5. Thermodynamic properties and atomic structure of Ca-based liquid alloys

    Science.gov (United States)

    Poizeau, Sophie

    To identify the most promising positive electrodes for Ca-based liquid metal batteries, the thermodynamic properties of diverse Ca-based liquid alloys were investigated. The thermodynamic properties of Ca-Sb alloys were determined by emf measurements. It was found that Sb as positive electrode would provide the highest voltage for Ca-based liquid metal batteries (1 V). The price of such a battery would be competitive for the grid-scale energy storage market. The impact of Pb, a natural impurity of Sb, was predicted successfully and confirmed via electrochemical measurements. It was shown that the impact on the open circuit voltage would be minor. Indeed, the interaction between Ca and Sb was demonstrated to be much stronger than between Ca and Pb using thermodynamic modeling, which explains why the partial thermodynamic properties of Ca would not vary much with the addition of Pb to Sb. However, the usage of the positive electrode would be reduced, which would limit the interest of a Pb-Sb positive electrode. Throughout this work, the molecular interaction volume model (MIVM) was used for the first time for alloys with thermodynamic properties showing strong negative deviation from ideality. This model showed that systems such as Ca-Sb have strong short-range order: Ca is most stable when its first nearest neighbors are Sb. This is consistent with what the more traditional thermodynamic model, the regular association model, would predict. The advantages of the MIVM are the absence of assumption regarding the composition of an associate, and the reduced number of fitting parameters (2 instead of 5). Based on the parameters derived from the thermodynamic modeling using the MIVM, a new potential of mixing for liquid alloys was defined to compare the strength of interaction in different Ca-based alloys. Comparing this trend with the strength of interaction in the solid state of these systems (assessed by the energy of formation of the intermetallics), the systems with

  6. FORMATION OF GRADIENT COATING OF Fe-BASED ALLOY WITH RARE EARTHS BY PLASMA SURFACING

    Institute of Scientific and Technical Information of China (English)

    L.J.Shang; A.Q.Sun; J.F.Chen; C.M.Zhang; Q.K.Cai

    2004-01-01

    A gradient coating of Fe-based alloy was manufactured with rare earths (RE) by plasma surfacing on Q235 steel substrate. The coatings were studied by using X-ray diffraction (XRD),scanning electron microscope(SEM),differential thermal analyzer (DTA ),and electron probe micro-analyzer (EPMA). The results show that the phases of the two kinds of coatings(with and without RE) both include α-Fe, Fe7C3, Fe3C, Cr2B, Fe2B and FeB. The microstructure ofF314 coating is mainly hypereutectic, the pro-phases Cr7C3 and Cr2B are loose, crassi, spiculate and contain microcracks. The brittleness of the coating is high, and the average hardness is 787 HV. When 0.8wt% RE was added into the F314 alloy, the microstructure varied from hypoeutectic to hypereutectic continuously, The hardness appears as gradient distribution with the highest value of 773 HV, meanwhile, the brittleness decreases significantly. The formation of gradient structure depends on the fallowing factors: (i) the conversion of RE. The addition of RE lowers the elements point and Fe-C eutectic temperature, thus the base metal melting acutely. (ii) the heating of plasma arc.Graded temperature results in directional solidification, thus the gradient structure forms easily. The main reasons for the hardness decrease with RE addition in the alloy are the ratio of hard phase lowering and the hardness of the hard phase decreasing.

  7. Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Emad M. Elgallad

    2016-01-01

    Full Text Available This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

  8. Microstructural studies on friction surfaced coatings of Ni-based alloys

    International Nuclear Information System (INIS)

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

  9. Reaction between Ti and boron nitride based investment shell molds used for casting titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The aim of this paper was to study the reaction between a Ti-6A1-4V alloy and boron nitride based investment shell molds used for investment casting titanium.In BN based investment shell molds,the face coatings are made of pretreated hexagonal boron nitride (hBN) with a few yttria (Y2O3) and colloidal yttria as binder.The Ti-6A1-4V alloy was melted in a controlled atmosphere induction furnace with a segment water-cooled copper crucible.The cross-section of reaction interface between Ti alloys and shell mold was investigated by electron probe micro-analyzer (EPMA) and microhardness tester.The results show that the reaction is not serious,the thickness of the reacting layer is about 30-50 tun,and the thickness of ct-case is about 180-200 μm.Moreover the o-case formation mechanism was also discussed.

  10. Lanthanide doped strontium-barium cesium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  11. Chemical abundance analysis of 19 barium stars

    Science.gov (United States)

    Yang, Guo-Chao; Liang, Yan-Chun; Spite, Monique; Chen, Yu-Qin; Zhao, Gang; Zhang, Bo; Liu, Guo-Qing; Liu, Yu-Juan; Liu, Nian; Deng, Li-Cai; Spite, Francois; Hill, Vanessa; Zhang, Cai-Xia

    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 Teff, surface gravities log g, metallicity [Fe/H] and microturbulence velocity ξt) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants as indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their Na, Al, α- and iron-peak elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-capture) process elements relative to the Sun. Their median abundances of [Ba/Fe], [La/Fe] and [Eu/Fe] are 0.54, 0.65 and 0.40, respectively. The Y I and Zr I abundances are lower than Ba, La and Eu, but higher than the α- and iron-peak elements for the strong Ba stars and similar to the iron-peak elements for the mild stars. There exists a positive correlation between Ba intensity and [Ba/Fe]. For the n-capture elements (Y, Zr, Ba, La), there is an anti-correlation between their [X/Fe] and [Fe/H]. We identify nine of our sample stars as strong Ba stars with [Ba/Fe] >0.6 where seven of them have Ba intensity Ba=2-5, one has Ba=1.5 and another one has Ba=1.0. The remaining ten stars are classified as mild Ba stars with 0.17<[Ba/Fe] <0.54.

  12. Internal nitridation of nickel-base alloys; Innere Nitrierung von Nickelbasis-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, U.; Christ, H.J. [Siegen Univ. (Gesamthochschule) (Germany). Inst. fuer Werkstofftechnik

    1998-12-31

    The chromuim concentration is the crucial variable in nitridation processes in nickel-base alloys. Extensive nitridation experiments with various specimen alloys of the system Ni-Cr-Al-Ti have shown that the Cr itself starts to form nitrides as from elevated initial concentrations of about 10 to 20 weight%, (depending on temperature), but that lower concentrations have an earlier effect in that they induce a considerable increase in the N-solubility of the nickel-base alloys. This causes an accelerated nitridation attack on the alloying elements Ti and Al. Apart from experimental detection and analysis, the phenomenon of internal nitridation could be described as well by means of a mathematical model calculating the diffusion with the finite-differences method and determining the precipitation thermodynamics by way of integrated equilibrium calculations. (orig./CB) [Deutsch] Im Verlauf der Hochtemperaturkorrosion von Nickelbasis-Superlegierungen kann durch beanspruchungsbedingte Schaedigungen der Oxiddeckschicht ein Verlust der Schutzwirkung erfolgen und als Konsequenz Stickstoff aus der Atmosphaere in den Werkstoff eindringen. Der eindiffundierende Stickstoff bildet vor allem mit den Legierungselementen Al, Cr und Ti Nitridausscheidungen, die zu einer relativ rasch fortschreitenden Schaedigung fuehren koennen. Eine bedeutende Rolle bei diesen Nitrierungsprozessen in Nickelbasislegierungen spielt die Cr-Konzentration in der Legierung. So ergaben umfangreiche Nitrierungsexperimente an verschiedenen Modellegierungen des Systems Ni-Cr-Al-Ti, dass Cr zwar selbst erst ab Ausgangskonzentrationen von ca. 10-20 Gew.% (abhaengig von der Temperatur) Nitride bildet, allerdings bereits bei geringen Konzentrationen die N-Loeslichkeit von Nickelbasis-Legierungen entscheidend erhoeht. Dies hat zur Folge, dass es zu einem beschleunigten Nitrierungsangriff auf die Legierungselemente Ti und Al kommt. Neben den experimentellen Untersuchungen konnte das Phaenomen der inneren

  13. Comparative evaluation of tensile bond strength of denture base resins to surface pretreated cobalt chromium base metal alloys--an in vitro study.

    OpenAIRE

    Aazad A; Shetty P; Bhat S; Joseph M

    2001-01-01

    This study was undertaken to evaluate the tensile bond strength of acrylic resins to surface pretreated Cobalt-chromium base metal alloy. A total of 60 tensile bar specimens were prepared. One half of the bar was cast in cobalt-chromium alloy and the other half made of denture base resins attached to the alloy following surface pretreatment. Two denture base resins and five surface pre-treatments were used which included sandblasting, acid etching, use of metal adhesive primers and the combin...

  14. Skeletal Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    Min Enze

    2004-01-01

    Looking toward 21 century, smaller, cleaner and more energy-efficient technology will be an important trend in the development of chemical industry. In light of the new process requirements,a number of technology breakthroughs have occurred. One of these discoveries, the magnetically stabilized bed (MSB), has been proven a powerful process for intensification. Since its initial research in the late 1980's at Research Institute of Petroleum Processing (RIPP), the MSB technology and related catalytic material have matured rapidly through an intensive research and engineering program, primarily focused on its scaling-up.In this paper, we report the discovery of a novel skeletal amorphous nickel-based alloy and its use in magnetically stabilized bed (MSB). Amorphous alloys are new kinds of catalytic materials with short-range order but long-range disorder structure. In comparison with Raney Ni, the skeletal amorphous nickel-based alloy has an increasingly higher activity in the hydrogenation of reactive groups and compounds including nitro, nitrile, olefin, acetylene, aromatics, etc. Up to now, the amorphous nickel based alloy catalysts, SRNA series catalyst, one with high Ni ratio have been commercially manufactured more than four year. The new SRNA catalyst has been successfully implemented for hydrogenation applications in slurry reactor at Balin Petrochemical, SINOPEC.SRNA catalyst with further improvement in catalytic activity and stability raise its relative stability to 2~4 times of that of conventional catalyst. In the course of the long-cycle operation of SRNA-4 the excellent catalyst activity and stability can bring about such advantage as low reaction temperature, good selectivity and low catalyst resumption.Magnetically stabilized bed (MSB), a fluidized bed of magnetizable particles by applying a spatially uniform and time-invariant magnetic field oriented axially relative to the fluidizing fluid flow, had many advantages such as the low pressure drop and

  15. Mechanisms of oxide layer formation and destruction on a chromia former nickel base alloy in HTR environment

    International Nuclear Information System (INIS)

    Haynes 230 alloy which contains 22 wt.% chromium could be a promising candidate material for structures and heat exchangers (maximum operating temperature: 850-950 C) in Very High Temperature Reactors (VHTR). The feasibility demonstration involves to valid its corrosion resistance in the reactor specific environment namely impure helium. The alloys surface reactivity was investigated at temperatures between 850 and 1000 C. We especially focused on the influence of different parameters such as concentrations of impurities in the gas phase (carbon monoxide and methane, water vapour/hydrogen ratio), alloy composition (activities of Cr and C, alloying element contents) and temperature. Two main behaviours have been revealed: the formation of a Cr/Mn rich oxide layer at 900 C and its following reduction at higher temperatures. At 900 C, the water vapour is the main oxidizing gas. However in the initial times, the carbon monoxide reacts at the metal/oxide interface which involves a gaseous transport through the scale; CO mainly oxidizes the minor alloying elements aluminium and silicon. Above a critical temperature TA, the carbon in solution in the alloy reduces chromia. To ascribe the scale destruction, a model is proposed based on thermodynamic interfacial data for the alloy, oxide layer morphology and carbon monoxide partial pressure in helium; the model is then validated regarding experimental results and observations. (author)

  16. Base-metal dental casting alloy biocompatibility assessment using a human-derived three-dimensional oral mucosal model.

    LENUS (Irish Health Repository)

    McGinley, E L

    2012-01-01

    Nickel-chromium (Ni-Cr) alloys used in fixed prosthodontics have been associated with type IV Ni-induced hypersensitivity. We hypothesised that the full-thickness human-derived oral mucosa model employed for biocompatibility testing of base-metal dental alloys would provide insights into the mechanisms of Ni-induced toxicity. Primary oral keratinocytes and gingival fibroblasts were seeded onto Alloderm™ and maintained until full thickness was achieved prior to Ni-Cr and cobalt-chromium (Co-Cr) alloy disc exposure (2-72 h). Biocompatibility assessment involved histological analyses with cell viability measurements, oxidative stress responses, inflammatory cytokine expression and cellular toxicity analyses. Inductively coupled plasma mass spectrometry analysis determined elemental ion release levels. We detected adverse morphology with significant reductions in cell viability, significant increases in oxidative stress, inflammatory cytokine expression and cellular toxicity for the Ni-Cr alloy-treated oral mucosal models compared with untreated oral mucosal models, and adverse effects were increased for the Ni-Cr alloy that leached the most Ni. Co-Cr demonstrated significantly enhanced biocompatibility compared with Ni-Cr alloy-treated oral mucosal models. The human-derived full-thickness oral mucosal model discriminated between dental alloys and provided insights into the mechanisms of Ni-induced toxicity, highlighting potential clinical relevance.

  17. Kinetics of crystallization of a Fe-based multicomponent amorphous alloy

    Indian Academy of Sciences (India)

    Arun Pratap; T Lilly Shanker Rao; Kinnary Patel; Mukesh Chawda

    2009-10-01

    The Fe-based multicomponent amorphous alloys (also referred to as metallic glasses) are known to exhibit soft magnetic properties and, it makes them important for many technological applications. However, metallic glasses are in a thermodynamically metastable state and in case of high temperature operating conditions, the thermally activated crystallization would be detrimental to their magnetic properties. The study of crystallization kinetics of metallic glasses gives useful insight about its thermal stability. In the present work, crystallization study of Fe67Co18B14Si1 (2605CO) metallic glass has been carried out using differential scanning calorimetry (DSC) technique. Mössbauer study has also been undertaken to know the phases formed during the crystallization process. The alloy shows two-stage crystallization. The activation energy has been derived using the Kissinger method. It is found to be equal to 220 kJ/mol and 349 kJ/mol for the first and second crystallization peaks, respectively. The Mössbauer study indicates the formation of -(Fe, Co) and (Fe, Co)3B phases in the alloy.

  18. Structural Changes of α Phase in Furnace Cooled Eutectoid Zn-Al Based Alloy

    Institute of Scientific and Technical Information of China (English)

    Y.H. Zhu; K.C. Chan; G.K.H. Pang; T.M. Yue; W.B. Lee

    2007-01-01

    Furnace cooling is a slow cooling process. It is of importance to study structural evolution and its effects on the properties of alloys during the furnace cooling. Decomposition of aluminium rich α phase in a furnace cooled eutectoid Zn-Al based alloy was studied by transmission electron microscopy. Two kinds of precipitates in the α phase were detected in the FCZA22 alloy during ageing at 170℃. One was the hcp transitional α"m phase which appears as directional rods and the round precipitates. The other was the fcc α'm phase.It was found that the transitional phase α'm grew in three preferential directions of , and . The orientation relationship between the α phase and transitional phase α'm was determined as (02-2)α'm(fcc)//(02-2)α(fcc), [-111]α'm(fcc)//[-233]α(fcc). The non-equilibrium phase decomposition of the α phase is discussed in correlation with the equilibrium phase relationships.

  19. Effect of Ni on Mg based hydrogen storage alloy Mg3Nd

    Institute of Scientific and Technical Information of China (English)

    TONG Yanqing; OUYANG Liuzhang; ZHU Min

    2006-01-01

    Magnesium-neodymium based alloys were prepared by induction melting in an alumina crucible under protection of pure argon atmosphere. XRD patterns show that the as-melted Mg-Nd and Mg3NdNi 0.1 diffraction peaks can be excellently indexed with D03 structure (BiF3 type, space group Fm3m ). The lattice constant of Mg3Nd phase is 0.7390 nm, which is determined by XRD analysis using Cohen's extrapolation method. The reversible hydrogen storage capacity reaches 1.95wt.% for Mg3Nd and 2.68wt.% for Mg3NdNi0.1 . The desorption of hydrogen takes place at 291 ℃ for Mg3Nd and at 250 ℃ for Mg3NdNi 0.1 . The alloys could absorb hydrogen at room temperature with rapid hydriding and dehydriding kinetics after only one cycle. The enthalpy (ΔH ) and entropy (ΔS ) of Mg3Nd-H dehydriding reaction were -68.2 kJ·mol-1 H2 and -0.121 kJ·(K·mol)-1 H2 determined by using van't Hoff plot according to the pressure-composition-isotherms (P-C-I) curve measured at different temperatures. Hydrogen absorption kinetic property of Mg3NdNi 0.1 alloy was also measured at room temperature.

  20. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton

    2012-09-01

    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  1. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    Science.gov (United States)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  2. Some effects of solidification kinetics on microstructure formation in aluminium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H. [Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2005-12-15

    The development of rapid solidification technologies and their effects has provided a stimulus to seek a deeper understanding of the mechanisms by which kinetics determine solidification microstructure formation, including its scale, morphology and phase constitution. Successful application of model predictions to real situations involves coupling of heat and fluid flow considerations to the thermodynamics and kinetics of competing solidification reactions. A key element in this competition is the formation temperature of the contending constituents and their morphologies which is beyond the present scope of experimental determination at the extremes of most rapid solidification processes. The present contribution focuses on recent work on measurements of formation temperature of constituents in Al-based alloys during Bridgman solidification for comparison with model predictions. Together with associated microstructural observations, the results indicate control by heterogeneous nucleation in the case of polygonal primary silicon in hypereutectic Al-Si alloys, while competitive growth is controlling for aluminide dendrites in Al-Fe, Al-Ni and Al-Ce or Al-La alloys, for which measured tip undercoolings accord well with values calculated from dendrite growth models. Also, values of equilibrium eutectic temperature obtained by extrapolation to zero growth velocity of growth temperatures in such systems agree well with reliable values obtained by other methods and values of kinetic constants for dendrites and eutectics derived from measured velocities for extinction of the dendritic constituent are shown to be in good accord with direct measurements.

  3. Effect of chemical composition and cooling conditions on solidification hot cracking of Ni-based alloys

    International Nuclear Information System (INIS)

    Ni-based alloys 690 present solidification hot cracks during welding of vapour generators. Hot cracks are qualitatively known to be due to the formation of inter-dendritic liquid films and of secondary phases down to low temperatures. This study aims at establishing the link between thermodynamics, solidification and hot cracking. Experimental solidification paths of high purity alloys (with varying Nb and Si contents) are obtained from quenching during directional solidification and TIG-welding experiments. They are compared to Thermo-Calc computations, assuming no diffusion in the solid. From directional solidification samples, good agreement between computed and experimental solidification paths is shown in the quenched liquid. Secondary arms of dendrites are affected by solid state diffusion of Nb. Combined effect of diffusion and solute build-up in the liquid phase modifies micro-segregation in the solid region. Solidification paths from welding specimens are similar to those of the solid region of quenched samples. Nb solid state diffusion is negligible but undercooling compensates the effect of solid state diffusion in directional solidification. Evolution of liquid fraction at the end of the solidification is in accordance with the hot cracking classification of the alloys. Nb favours formation of inter-dendritic liquid films and eutectic-like phases down to low temperature. (author)

  4. Dissolution Mechanism of a Zr Rich Structure in a Ni3Al Base Alloy

    Institute of Scientific and Technical Information of China (English)

    H.B. Mote.jadded; M. Soltanieh; S. Rastegari

    2011-01-01

    In the present research, the dissolution mechanism of a Zr rich structure during annealing of a Ni3Al base alloy containing Cr, Mo, Zr and B, was investigated. The annealing treatments were performed up to 50 h at 900, 1000 and 1100℃. The alloy used in this investigation was produced by vacuum-arc remelting technique. The results show that at the beginning of the process, a mixed interface reaction and local equilibrium (long range diffusion) mechanism controls the dissolution process. After a short time, this mechanism changes and the dissolution mechanism of the Zr rich structure changes to only long range diffusion of Zr element. According to this mechanism, the activation energy of this process is estimated to be about 143.3 kJ.mol-1. Also the phases that contribute to this structure and the transformations that occur at the final steps of solidification of this alloy were introduced. According to the results, at the final step of solidification, a peritectic type reaction occurs in the form of L+ y→Ni7Zr2 and →-Ni7Zr2 segregates from the melt. Following this transformation, →-Ni7Zr2 eutectic separates from the remaining Zr rich liquid. The solidification process will be terminated by a ternary eutectic reaction in the form of L→y+Ni5Zr+Ni7Zr2.

  5. ANN-based wear performance prediction for plasma nitrided Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kahraman, Fatih; Karadeniz, Sueleyman; Durmus, Izmir; Durmus, Huelya

    2012-07-01

    Surface modification of a Ti6Al4V titanium alloy was made by the plasma nitriding process. Plasma nitriding was performed in a constant gas mixture of 20% H{sub 2} -80% N{sub 2} at temperatures between 700 and 1000 C and process times between 2 and 15 h. Samples nitrided at different treatment times and temperatures were subjected to the dry sliding wear test using the pin-on-disc set up under 80N normal load with rotational speed of counter face disc of 0.8 m/s at room conditions. An artificial neural network (ANN) model of was developed for prediction of wear performance of the plasma nitrided Ti6Al4V alloy. The inputs of the ANN model were processing times and temperatures, diffusion layer thickness, Ti{sub 2}N thickness, TiN thickness and hardness. The output of the ANN model was wear loss. The model is based on the multilayer backpropagation neural technique. The ANN was trained with a comprehensive dataset collected from experimental conditions and results of authors. The model can be used for the prediction of wear properties of Ti6Al4V alloys nitrided at different parameters. The ANN model demonstrated the best statistical performance with the experimental results.

  6. Co-based soft magnetic bulk glassy alloys optimized for glass-forming ability and plasticity

    Indian Academy of Sciences (India)

    LI LI; HUAIJUN SUN; YUNZHANG FANG; JIANLONG ZHENG

    2016-06-01

    Co-based bulk glassy alloys (BGAs) have become more and more important because of their nearly zero magnetostriction and high giant magneto-impedance effect. Here, we report the improvement of glass-formingability (GFA), soft-magnetic properties and plasticity by a small addition of Mo atoms in CoFeBSiNbMo BGAs.(Co$_{0.6}$Fe$_{0.4}$)$_{69}$B$_{20.8}$Si$_{5.2}$Nb$_{5−x}$Mo$_{x}$ ferromagnetic BGA cylindrical glassy rods were fabricated successfully with adiameter of 5 mm by conventional copper mould casting method. It reveals that the substitution of a small amount of Mo for Nb makes the composition to approach a eutectic point and effectively enhances the GFA of alloy. Inaddition to high GFA and superhigh strength, the compressive test shows that the Mo addition can improve the plasticity for the obtained BGAs. The combination of high GFA, excellent soft-magnetic properties and good plasticitydemonstrated in our alloys is promising for the future applications as functional materials.

  7. Impact properties of vanadium-base alloys irradiated at < 430 C

    International Nuclear Information System (INIS)

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys

  8. Impact properties of vanadium-base alloys irradiated at < 430 C

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys.

  9. Effect of Cu addition on the GFA, structure and properties of Fe-Co-based alloy

    Directory of Open Access Journals (Sweden)

    S. Lesz

    2012-06-01

    Full Text Available Purpose: The aim of the paper was investigation of the effect of Cu addition on GFA (Glass Forming Ability, structure, magnetic and mechanical properties of amorphous Fe-Co-B-Si-Nb alloy.Design/methodology/approach: The following experimental techniques were used: differential thermal analysis (DTA, transmission electron microscopy (TEM and X-ray diffraction (XRD method, measurements of magnetic properties (VSM method, Vickers microhardness (HV.Findings: It was shown that when Cu is added to the Fe-Co-based alloy, increase of the GFA and change of the magnetic properties was obtained.Research limitations/implications: The results can give more details to understand the relationship between structure, magnetic and mechanical properties. Thus can be useful for practical application of these alloys.Practical implications: The (Fe36Co36B19Si5Nb4100-xCux (x=0 and 0.6 metallic glasses due to their excellent soft magnetic properties have shown great industrial value for commercial application. Many products consisting of these kinds of metallic glasses have been widely used, for example anti-theft labels, precision sensor material, and high efficient magnetic transformers in electronic industry.Originality/value: The applied investigation methods are suitable to determine the changes of GFA and structure combined with magnetic and mechanical properties of (Fe36Co36B19Si5Nb4100-xCux (x=0 and 0.6 metallic glasses.

  10. Fatigue properties of alloy 718 overlay-coated with a Co-based X40 alloy by the Micro Spark Coating

    Science.gov (United States)

    Kamma, Ryohta; Sakaguchi, Motoki; Okazaki, Masakazu; Shimoda, Yukihiro; Uchiyama, Takehiko; Ochiai, Hiroyuki; Watanabe, Mitsutoshi

    Micro Spark Coating (MSC) has been developed as a new functional coating process for Ni-based superalloys used in advanced gas turbines. In this study, some metallurgical and mechanical properties of a MSC layer made of a Co-based wear resisting alloy (X40), and its influence on the high temperature fatigue properties of Ni-based superalloy, Alloy718, were investigated. Prior evaluation of the metallurgical and mechanical properties of the MSC layer that the cavity fraction of MSC layer significantly decreased during the thermal exposure period at 650°C associating with the generation of an oxide phase, progressive sintering and the subsequent increase in hardness and elastic modulus of MSC layer. However, at 480°C these changes were not significant even after 1000hrs exposure. It was found from the high temperature fatigue tests at 480°C and 650°C that the fatigue life of the specimen with MSC layer was almost comparable to that of bare Alloy718 specimen at 480°C, while at 650°C the life of the former was slightly longer than that of the latter. These results suggested that the MSC would have a potential to add a new function to Ni-based superalloy without a reduction in fatigue properties at elevated temperature.

  11. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE

    CERN Document Server

    Anderson, NG; Firsching, M; de Ruiter, N; Schleich, N; Butzer, J S; Cook, N J; Grasset, R; Campbell, M; Scott, N J A; Anderson, N G

    2010-01-01

    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 A 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 f...

  12. Barium borosilicate glass as a matrix for the uptake of dyes

    International Nuclear Information System (INIS)

    Barium borosilicate (BBS) and sodium borosilicate (SBS) glass samples, prepared by the conventional melt-quench method, were used for the uptake of Rhodamine 6G dye from aqueous solution. The experimental conditions were optimized to get maximum uptake and was found to be 0.4 mg of dye per gram of BBS glass sample. For the same network former to modifier ratio, barium borosilicate glasses are found to have improved extent of uptake for the dye molecules from aqueous solutions compared to sodium borosilicate glasses. Based on 29Si MAS NMR studies on these glasses, it is inferred that significantly higher number of non-bridging oxygen atoms present in barium borosilicate glasses compared to sodium borosilicate glasses is responsible for its improved uptake of Rhodamine 6G dye. 11B MAS NMR studies have confirmed the simultaneous existence of boron in BO3 and BO4 configurations in both barium borosilicate and sodium borosilicate glasses. The luminescence studies have established that the dye molecule is incorporated into the glass matrix through ion exchange mechanism by replacing the exchangeable ions like Na+/Ba2+ attached with the non-bridging oxygen atoms present in the glass.

  13. Filterless pre-concentration by co-precipitation by formation of crystalline precipitate in the analysis of barium by FIA-FAES

    DEFF Research Database (Denmark)

    Plamboeck, C.; Westtoft, H.C.; Pedersen, S.A.;

    2003-01-01

    A novel method based on flow injection analysis (FIA) and flame atomic emission spectrometry (FAES) is presented. It was developed for direct determination of barium in drinking water, in natural water, in digested samples of bone and liver, in saline water and in a standard reference material...... (NIST SRM 1640). It was found that digestion of bone by an incineration procedure was required, in order to extract most of the barium. In the FIA manifold, barium was pre-concentrated by co-precipitation with lead chromate leading to a crystalline deposit that adhered well to the inner walls of a nylon...

  14. The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

    Directory of Open Access Journals (Sweden)

    N. Al-Aqeeli

    2014-01-01

    Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

  15. Lattice specific heat and local density of states of Ni-based dilute alloys at low temperature

    Indian Academy of Sciences (India)

    P D Semlaty; Kapil Dev; P N Ram

    2006-06-01

    A detailed theoretical study of the low-temperature lattice specific heat of Ni-based dilute alloys has been carried out. Lattice Green's function method has been used to calculate the local density of states of substitutional impurities and lattice specific heat in different alloys. The resonance condition has been investigated for possible occurrence of resonance modes. Except in NiCr and NiMn, low-frequency resonance modes have been obtained in all the alloys. However, no localized mode was obtained. The impurity-induced increase in lattice specific heat is explained on the basis of the obtained resonance modes. The calculation shows an excellent agreement with the measured lattice specific heat in these alloys

  16. Plastic Behavior of a Nickel-Based Alloy under Monotonic-Tension and Low-Cycle-Fatigue Loading

    Energy Technology Data Exchange (ETDEWEB)

    Huang, E-Wen [ORNL; Barabash, Rozaliya [ORNL; Wang, Yandong [ORNL; Clausen, Bjorn [ORNL; Li, Li [ORNL; Liaw, Peter K [University of Tennessee, Knoxville (UTK); Ice, Gene E [ORNL; Yang, Dr Ren [Argonne National Laboratory (ANL); Choo, Hahn [ORNL; Pike, Lee M [ORNL; Klarstrom, Dwaine L [ORNL

    2008-01-01

    The plasticity behavior of the annealed HASTELLOY C-22HSTM alloy, a face-centered cubic (FCC), nickel-based superalloy, was examined by the in-situ neutron-diffraction experiments at room temperature. Monotonic-tension and low-cycle-fatigue experiments were conducted to observe the plastic behavior of the alloy. The tension straining and cyclic-loading deformation were studied as a function of the stress. The plastic behaviors during the deformation are discussed in the light of the relationship between the stress and dislocation-density evolutions. The calculated dislocation-density evolutions within the alloys reflect the strain hardening and cyclic hardening/softening. Experimental lattice strains are compared to verify the hardening mechanism at the selected stress levels for tension and cyclic loadings. Combining with the calculations of the dislocation densities, the neutron-diffraction experiments give an evidence of the strain and cyclic hardening of the alloy.

  17. Europium-doped barium bromide iodide

    Energy Technology Data Exchange (ETDEWEB)

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  18. Barium dithionate as an EPR dosemeter.

    Science.gov (United States)

    Baran, M P; Bugay, O A; Kolesnik, S P; Maksimenko, V M; Teslenko, V V; Petrenko, T L; Desrosiers, M F

    2006-01-01

    Electron paramagnetic resonance (EPR) dosimetry is growing in popularity and this success has encouraged the search for other dosimetric materials. Previous studies of gamma-irradiated barium dithionate (BaS(2)O(6) x 2H(2)O) have shown promise for its use as a radiation dosemeter. This work studies in greater detail several essential attributes of the system. Special attention has been directed to the study of EPR response dependences on microwave power, irradiation temperature, minimum detectable dose and post-irradiation stability. PMID:16565205

  19. Barium enema findings of milk allergy in infants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyoung Ju; Kim, Mi Jeong; Lee, Hee Jung [Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2006-09-15

    We wanted to evaluate the barium enema findings of milk allergy in infants. Retrospective evaluation of the plain abdominal radiography and barium enema findings was performed in fifteen young infants suffering with milk allergy. The presence of gaseous distension, rectal gas, paralytic ileus and mechanical obstruction was evaluated on the plain radiography. The presence of spasm, a transitional zone, a reversed rectosigmoid index and mucosal irregularity was analyzed on the barium enema; the presence of barium retention was also evaluated on 24-hour-delayed plain radiography. Paralytic ileus was the most common finding on the plain radiography (93%). On the barium enema, continuous spasm of the colon, ranging from the rectum to the descending colon, was revealed in ten infants (67%). A transitional zone was observed in one infant and a reversed rectosigmoid index was revealed in four. Mucosal irregularity was observed in two infants. Barium retention was demonstrated in 11 of fifteen cases: throughout the entire colon (n = 3), from the rectum to the descending colon (n = 7), and up to the transverse colon (n = 1). The most common barium enema finding of milk allergy in infants was spasm of the distal colon. The other findings were a transitional zone, a reversed rectosigmoid index, mucosal irregularity and barium retention.

  20. Fatigue Properties of Welded Butt Joint and Base Metal of MB8 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Ying-xia YU

    2016-09-01

    Full Text Available The fatigue properties of welded butt joint and base metal of MB8 magnesium alloy were investigated. The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine for both welded butt joint and base metal specimens with the same size and shape. The fatigue fractures were observed and analyzed by a scanning electron microscope of 6360 LA type. The experimental results show that the fatigue performance of the welded butt joint of MB8 magnesium alloy is sharply decreased. The conditional fatigue limit (1×107 of base metal and welded butt joint is about 69.41 and 32.76 MPa, respectively. The conditional fatigue limit (1×107 of the welded butt joint is 47.2 % of that of base metal. The main reasons are that the welding can lead to stress concentration in the weld toe area, tensile welding residual stress in the welded joint, as well as grain coarsening in the welding seam. The cleavage steps or quasi-cleavage patterns present on the fatigue fracture surface, indicating the fracture type of the welded butt joint belongs to a brittle fracture.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.9132

  1. Microstructure characteristics and compressive properties of NiAl-based multiphase alloy during heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, L.Y., E-mail: lysheng@yeah.net [Peking University, Beijing 100871 (China); PKU-HKUST ShenZhen-Hong Kong Institution, Shenzhen 518057 (China); Xie, Y. [Hunan Electric Power Test and Research Institute, Changsha 410007 (China); Xi, T.F. [Peking University, Beijing 100871 (China); Guo, J.T. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zheng, Y.F. [Peking University, Beijing 100871 (China); Ye, H.Q. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-11-15

    mechanical properties of the NiAl-based multiphase alloy significantly.

  2. Synthesis and characterization of Mg-based amorphous alloys and their use for decolorization of Azo dyes

    International Nuclear Information System (INIS)

    Mg-based alloys are light weight and have wide range of applications in the automotive industry. These alloys are widely used because of their very attractive physical and mechanical properties and corrosion resistance. The properties and applications can be further improved by changing the nature of materials from crystalline to amorphous. In this study, melt spun ribbons (MSRs) of Mg70Zn25Ca5 Mg68Zn27Ca5 alloys were prepared by melt spinning technique by using 3-4N pure metals. Characterization of the samples was done by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and energy dispersive x-ray analyzer (EDAX). Microstructural investigations were conducted by using scanning electron microscopy (SEM), atomic force microscopy (AFM) as well as optical and stereo scan microscopy techniques. DSC results showed multistage crystallization. Activation energy was found to be 225 kJ/mol by Kissinger method indicating good thermal stability against crystallization. XRD, DSC, SEM and EDS (energy dispersive spectroscopy) results are agreed very well. In order to study decolorization, the MSRs of Mg70Zn25Ca5 Mg68Zn27Ca5 alloys were treated repeatedly with various azo dyes at room temperature. In order to compare the results, MSRs of amorphous Zr- and Ni-based metallic glasses were also treated. Reaction of MSRs with azo dyes results in their decolorization in a few hours. Decolorization of azo dyes takes place by introducing amorphous MSRs which results in breaking the -N=N- bonds that exist in dye contents. It is concluded that Mg-based alloys are useful for paint and dye industries and will be beneficial to control water pollution. Comparison of results showed that Mg-based alloys are more efficient than Zr- and Ni-based amorphous alloys for decolorization of azo dyes

  3. Barium and radium migration in unconsolidated Canadian geological materials

    International Nuclear Information System (INIS)

    This report describes the results of laboratory studies on the distribution coefficients of radium and barium in samples of unconsolidated geologic materials. Graphs of Ksub(d) versus solution concentration for the respective elements showed constant Ksub(d) values in the low concentration range suggesting that, at low concentrations, a distribution coefficient is a valid means of representing the geochemical reactions of both barium and radium. The Ksub(d) values for barium range between 60 and 3500 ml/g. The values appear to be influenced by the amount of barium occurring naturally in the soil materials and thus there is little possiblility of using barium as an analog of radium in laboratory experiments. The Ksub(d) values of radium vary from 50 to 1000 ml/g indicating that a wide range of geological materials have a substantial capacity to retard the migration of radium

  4. Effect of Nb on barium titanate prepared from citrate solutions

    Directory of Open Access Journals (Sweden)

    Stojanović Biljana D.

    2002-01-01

    Full Text Available The influence of the addition of dopants on the microstructure development and electrical properties of BaTiO3 doped with 0.2, 0.4, 0.6, 0.8 mol% of Nb and 0.01 mol% of Mn based compounds was studied. Doped barium titanate was prepared using the polymeric precursor method from citrate solutions. The powders calcined at 700°C for 4 hours were analysed by infrared (IR spectroscopy to verify the presence of carbonates, and by X-ray diffraction (XRD for phase formation. The phase composition, microstructure and dielectric properties show a strong dependence on the amount of added niobium.

  5. Pulsating aurora induced by upper atmospheric barium releases

    Science.gov (United States)

    Deehr, C.; Romick, G.

    1977-01-01

    The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.

  6. Processing and applications of intermetallic {gamma}-TiAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, H. [Stuttgart Univ. (Germany). Inst. fuer Metallkunde; Kestler, H. [Metallwerk Plansee AG, Reutte/Tyrol (Austria)

    2000-09-01

    Development and processing of high-temperature materials is the key to technological advancements in engineering areas where materials have to meet extreme requirements. Examples for such areas are the aerospace and spacecraft industry or the automotive industry. New structural materials have to be ''stronger, stiffer, hotter, and lighter'' to withstand the extremely demanding conditions in the next generation of aircraft engines, space vehicles, and automotive engines. Intermetallic {gamma}-TiAl-based alloys show a great potential to fulfill these demands. (orig.)

  7. Nondestructive evaluation of SCC on the surface of Ni-base alloy by microwaves

    International Nuclear Information System (INIS)

    To detect stress corrosion cracking (SCC) and evaluate its depth on the surface of Ni-base alloys, a microwave microscope was employed. An open-ended coaxial line sensor was used to increase the spatial resolution. The working frequency was 110 GHz and the standoff distance between the sensor and the sample was 60 μm. The shape of SCC was obtained by microwave imaging. By measuring the amplitude of reflection coefficient, detection of SCC was achieved and V-shaped and W-shaped characteristic signal was obtained. The distribution of SCC depth along the crack length was evaluated using the measured amplitude of reflection coefficient. (author)

  8. High-cycle Fatigue Properties of Alloy718 Base Metal and Electron Beam Welded Joint

    Science.gov (United States)

    Ono, Yoshinori; Yuri, Tetsumi; Nagashima, Nobuo; Sumiyoshi, Hideshi; Ogata, Toshio; Nagao, Naoki

    High-cycle fatigue properties of Alloy 718 plate and its electron beam (EB) welded joint were investigated at 293 K and 77 K under uniaxial loading. At 293 K, the high-cycle fatigue strength of the EB welded joint with the post heat treatment exhibited somewhat lower values than that of the base metal. The fatigue strengths of both samples basically increased at 77 K. However, in longer life region, the EB welded joint fractured from a blow hole formed in the welded zone, resulting in almost the same fatigue strength at 107 cycles as that at 293 K.

  9. Wear resistance and hot corrosion behaviour of laser cladding Co-based alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    2Cr13 stainless steel was surface cladded with Co-based alloy using a high power carbon dioxide laser. The microstructure, wear resistance and corrosion properties of the clad layer were investigated. It is found that the high temperature corrosion behavior and wearing resistant property of the clad layer are 3 and 2.5 times higher than those of the parent metal. Under the high temperature molten lead sulphate salt corrosion condition, the clad layer fails by spalling which is caused by intergrannular corrosion within the clad layer. The fine dendritic structure and the oxide help to retard the penetration of the sulphur ion that induces the intergrannular corrosion.

  10. Intragranular nucleation sites of massive gamma grains in a TiAl-based alloy

    DEFF Research Database (Denmark)

    Dey, Suhash Ranjan; Bouzy, E.; Hazotte, A.

    2007-01-01

    Massive gamma grains were generated in a TiAl-based alloy through ice-water quenching from the alpha domain. Apart from those located along alpha(2)/alpha(2) grain boundaries, a few massive gamma grains were detected inside the alpha(2) grains. Some of these intragranular grains were revealed...... to be attached to particular alpha(2) twins (K-1: "{212103}" eta(1): ), in a Blackburn orientation relationship with them. Others were identified as developing in feathery colonies of similar crystallographic orientation. Whatever the nucleation site, further growth of all massive gamma grains involves...

  11. Interface reaction between nickel-base self-fluxing alloy coating and steel substrate

    Science.gov (United States)

    Otsubo, F.; Era, H.; Kishitake, K.

    2000-06-01

    The interface reaction between a nickel-base, self-fluxing alloy coating and a steel substrate has been investigated to examine the formation of “pores,” which are observed along the interface of used boiler tubes. It was found that lumpy precipitates form along the interface instead of pores after heating at high temperatures and that the precipitates are of Fe2B boride. The adhesion strength of the coating is not decreased by the formation of Fe2B precipitates along the interface because of the increase of the adhesion due to interdiffusion.

  12. Effect of the fiber orientation on the deformation mechanisms of magnesium-alloy based composite

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Gergely [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic); Trojanová, Zuzanka, E-mail: ztrojan@met.mff.cuni.cz [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic); Száraz, Zoltán [Institute for Energy and Transport, Joint Research Centre, Westerduinweg 3, NL-1755ZG Petten (Netherlands); Minárik, Peter; Máthis, Kristián [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic)

    2015-09-03

    The influence of the orientation of the fiber reinforcement on the deformation mechanisms of Mg–Al–Ca alloy-based composite has been investigated in-situ using acoustic emission and neutron diffraction methods. Results indicate that the twinned volume is the smallest, when the fibers plane is perpendicular to the loading direction. Residual thermal stresses having a tensile character are present in the as-received composites, which gradually vanishing during compressive straining. The load transfer from the matrix to fiber has been found more effective for specimens with fiber planes aligned with the loading direction, which is in agreement with the theoretical shear-lag model.

  13. Formation of a nanodispersed metal-matrix structure during a combined high-energy mechanical alloying of powders of aluminum-based SiC-containing alloys

    Science.gov (United States)

    Popov, V. A.; Cherdyntsev, V. V.

    2009-01-01

    Phase and structural state of composite materials produced by combined mechanical alloying of the AK12M2 and D16 powder alloys with silicon carbide in high-energy planetary mills with the use of ball charging and quasi-cylindrical bodies have been studied. It has been found out that the type of bodies substantially affects the mutual solubility of components in the systems investigated, as well as the perfection of the crystal lattice of the material treated, and its adhesion to the bodies and to the inner surface of the drum. It is shown that the use of balls favors an enhanced mutual solubility of the components and stipulates higher deformation of the crystal lattice of the product in comparison with the quasi-cylinder grinding bodies. The differences observed are discussed based on the calculated data obtained earlier for the ratio of normal and tangential components of energy consumption for different types of grinding bodies.

  14. Red chlorophyll: the new barium?

    Science.gov (United States)

    Hennig, G W

    2012-05-01

    Imaging of gastrointestinal (GI) motility remotely through the abdominal wall has always been a tradeoff between resolution and invasiveness. Skin reflects and/or absorbs wavelengths of radiation in the ultraviolet and visible ranges, but is largely transparent to both high-energy radiation (Gamma to X-rays; cinematography has excellent spatial and temporal resolution, but ionization can produce acute and long-term deleterious effects to the patient or animal. Other 'slice-based' imaging techniques such as ultrasound/MRI/CT minimize tissue damage, but are limited in the planar area that can be imaged in a timely fashion. This viewpoint article will summarize and explore the implications of recent advances in infrared imaging of the GI tract, in particular, an article published in this issue of NGM entitled 'In vivo dynamic imaging of intestinal motions using diet-related autofluorescence' in which the authors have used infrared imaging in combination with that most elusive ingredient, standard mouse chow, to capture the motions of the mouse GI tract. PMID:22489835

  15. Barium appendicitis: A single institution review in Japan

    Science.gov (United States)

    Katagiri, Hideki; Lefor, Alan Kawarai; Kubota, Tadao; Mizokami, Ken

    2016-01-01

    AIM To review clinical experience with barium appendicitis at a single institution. METHODS A retrospective review of patients admitted with a diagnosis of acute appendicitis, from January 1, 2013 to December 31, 2015 was performed. Age, gender, computed tomography (CT) scan findings if available, past history of barium studies, pathology, and the presence of perforation or the development of complications were reviewed. If the CT scan revealed high density material in the appendix, the maximum CT scan radiodensity of the material is measured in Hounsfield units (HU). Barium appendicitis is defined as: (1) patients diagnosed with acute appendicitis; (2) the patient has a history of a prior barium study; and (3) the CT scan shows high density material in the appendix. Patients who meet all three criteria are considered to have barium appendicitis. RESULTS In total, 396 patients were admitted with the diagnosis of acute appendicitis in the study period. Of these, 12 patients (3.0%) met the definition of barium appendicitis. Of these 12 patients, the median CT scan radiodensity of material in the appendix was 10000.8 HU, ranging from 3066 to 23423 HU (± 6288.2). In contrast, the median CT scan radiodensity of fecaliths in the appendix, excluding patients with barium appendicitis, was 393.1 HU, ranging from 98 to 2151 HU (± 382.0). The CT scan radiodensity of material in the appendices of patients with barium appendicitis was significantly higher than in patients with nonbarium fecaliths (P < 0.01). CONCLUSION Barium appendicitis is not rare in Japan. Measurement of the CT scan radiodensity of material in the appendix may differentiate barium appendicitis from routine appendicitis.

  16. Wideband and enhanced microwave absorption performance of doped barium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Pingyuan; Xiong, Kun [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Ju, Kui [Guizhou Institute of Metallurgy and Chemical Engineering, Guiyang 550002 (China); Li, Shengnan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2015-07-01

    To achieve stronger microwave attenuation and larger bandwidth in electromagnetic absorber, the nickel ions (Ni{sup 2+}) and manganese ions (Mn{sup 2+}) were employed to partially replace the cobalt ions (Co{sup 2+}) in BaCoTiFe{sub 10}O{sub 19}, and the doped barium hexaferrite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19}) powders were synthesized via the sol–gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the ferrite powders with the paraffin. The X-ray diffraction (XRD) patterns of the doped ferrites confirmed the formation of the M-type barium ferrite, and no other types of barium ferrite could be found. Based on the electromagnetic parameters measured by the vector net-analyzer, it was found that the composite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19}) possessed a minimum reflection loss of −52.8 dB at 13.4 GHz with a matching thickness of 1.8 mm and the bandwidth below −15 dB was 5.8 GHz. Moreover, the maximum attenuation of Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could reach −69 dB when its thickness was 1.8 mm, and also the bandwidth less than −20 dB was ranging from 13.2 GHz to 18 GHz. Thus, Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could be the good microwave absorbers, which have great potentials to be applied in the high frequency fields of the microwave absorbing materials. - Highlights: • The Co was first time substituted by Mn–Ni in ferrites. • The substituted ferrites had good microwave absorption. • The doped ferrites had broad bandwidth and low reflection loss.

  17. Transient liquid phase bonding of titanium-, iron- and nickel-based alloys

    Science.gov (United States)

    Rahman, A. H. M. Esfakur

    The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint

  18. Friction and wear with a single-crystal abrasive grit of silicon carbide in contact with iron base binary alloys in oil: Effects of alloying element and its content

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with various iron-base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a rider of 0.025-millimeter-radius, single-crystal silicon carbide in mineral oil. Results indicate that atomic size and content of alloying element play a dominant role in controlling the abrasive-wear and -friction properties of iron-base binary alloys. The coefficient of friction and groove height (wear volume) general alloy decrease, and the contact pressure increases in solute content. There appears to be very good correlation of the solute to iron atomic radius ratio with the decreasing rate of coefficient of friction, the decreasing rate of groove height (wear volume), and the increasing rate of contact pressure with increasing solute content C. Those rates increase as the solute to iron atomic radius ratio increases from unity.

  19. PLUTONIUM-THORIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  20. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms

    International Nuclear Information System (INIS)

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale (∼ 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr2O3 nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr2O3 nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary media and to tackle some