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Sample records for chromia forming alloys

  1. Rare earth oxide coatings to decrease high temperature degradation of chromia forming alloys

    Directory of Open Access Journals (Sweden)

    Stela Maria de Carvalho Fernandes

    2004-03-01

    Full Text Available The addition of small quantities of reactive elements such as rare earths (RE to chromia or alumina forming alloys improves the high temperature oxidation resistance. Traditionally, these elements are alloying additions or are added as oxides to form a dispersion. The alloys can also be coated with RE oxides. Several methods can be used to coat alloy substrates with RE oxides and the sol-gel process is considered to be quite efficient, as it generates the very small oxide particles. This paper presents the influence of surface coatings of Ce, La, Pr, and Y oxide gels on the oxidation behavior of an Fe-20Cr alloy at 1000 °C. The morphology of the rare earth (RE oxide coatings varied with the nature of RE. The oxidation rate of RE oxide coated Fe-20Cr was significantly less than that of the uncoated alloy. The extent of influence the RE oxide coating exercised on the oxidation rate decreased in the following order: La, Ce, Pr, Y. The scale formed in the presence of RE oxide was very thin, fine grained and adherent chromia. A direct correlation between rare earth ion radius and the extent of influence on chromia growth rate at 1000 °C was observed.

  2. Controlled reactions between chromia and coating on alloy surface

    DEFF Research Database (Denmark)

    Linderoth, Søren

    1996-01-01

    An electrically conducting Sr-doped lanthanum chromite (LSC) coating has been produced by reacting a coating of fine particles of La oxide and Sr oxide with chromia formed as an external scale on a metallic alloy. In addition to the formation of LSC the coating also resulted in much reduced...... buckling of the underlying chromia layer compared with a non-coated alloy....

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

    Energy Technology Data Exchange (ETDEWEB)

    Chyrkin, Anton

    2011-12-05

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of δ-Ni{sub 3}Nb and (Ni,Mo,Si){sub 6}C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900-1000 C in oxidation-induced chromium depletion in the subsurface zone of the alloy. Microstructural analyses of the cross-sectioned specimens revealed that this process results in formation of a wide subsurface zone in which the mentioned strengthening phases are dissolved, in spite of the fact that both phases do not contain substantial amounts of the scale-forming element chromium. The cross-sectional analyses revealed that, in parallel to the formation of a precipitate depleted zone, a thin, continuous layer of niobium-rich intermetallic precipitates formed in the immediate vicinity of the scale/alloy interface. The Subsurface Phase Enrichment (abbreviated as SPE) was shown to be the result of an uphill-diffusion of niobium, i.e. the element stabilizing the strengthening precipitates δ-Ni{sub 3}Nb, in the chromium activity gradient and is thus a natural consequence of the oxidation-induced chromium depletion beneath the chromia scale. The thermodynamic calculations carried out using the Thermo-Calc/DICTRA software packages revealed that in alloy 625 the chemical activity of niobium decreases with decreasing chromium content. As chromium is being continuously removed from the alloy as the result of the chromia scale growth, the zone of lowest Nb-activity is formed in the location with the lowest chromium concentration, i.e. the scale/alloy interface. This creates a driving force for Nb to diffuse towards the scale/alloy interface against its own concentration gradient, which is known

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

    Energy Technology Data Exchange (ETDEWEB)

    Chyrkin, Anton

    2011-12-05

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of δ-Ni{sub 3}Nb and (Ni,Mo,Si){sub 6}C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900-1000 C in oxidation-induced chromium depletion in the subsurface zone of the alloy. Microstructural analyses of the cross-sectioned specimens revealed that this process results in formation of a wide subsurface zone in which the mentioned strengthening phases are dissolved, in spite of the fact that both phases do not contain substantial amounts of the scale-forming element chromium. The cross-sectional analyses revealed that, in parallel to the formation of a precipitate depleted zone, a thin, continuous layer of niobium-rich intermetallic precipitates formed in the immediate vicinity of the scale/alloy interface. The Subsurface Phase Enrichment (abbreviated as SPE) was shown to be the result of an uphill-diffusion of niobium, i.e. the element stabilizing the strengthening precipitates δ-Ni{sub 3}Nb, in the chromium activity gradient and is thus a natural consequence of the oxidation-induced chromium depletion beneath the chromia scale. The thermodynamic calculations carried out using the Thermo-Calc/DICTRA software packages revealed that in alloy 625 the chemical activity of niobium decreases with decreasing chromium content. As chromium is being continuously removed from the alloy as the result of the chromia scale growth, the zone of lowest Nb-activity is formed in the location with the lowest chromium concentration, i.e. the scale/alloy interface. This creates a driving force for Nb to diffuse towards the scale/alloy interface against its own concentration gradient, which is known

  5. Stress release phenomena in chromia scales formed on NiCr-30 alloys: Influence of metallurgical parameters

    Science.gov (United States)

    Guerain, M.; Goudeau, P.; Grosseau-Poussard, J. L.

    2011-11-01

    Stress release phenomena are studied for α-Cr2O3 thermal oxide films grown on NiCr-30 alloys. The influence of specific metallurgical parameters, such as cooling rate and initial surface roughness, is investigated thanks to Raman spectroscopy. Systematic correlations are established between the residual stress level in the scales and the damage rate resulting from a delamination process by buckling. Different buckling morphologies are characterized mainly according to the cooling rate range.

  6. Protection of zirconium by alumina- and chromia-forming iron alloys under high-temperature steam exposure

    Science.gov (United States)

    Terrani, Kurt A.; Parish, Chad M.; Shin, Dongwon; Pint, Bruce A.

    2013-07-01

    The viability of advanced oxidation-resistant Fe-base alloys to protect zirconium from rapid oxidation in high-temperature steam environments has been examined. Specimens were produced such that outer layers of FeCrAl ferritic alloy and Type 310 austenitic stainless steel were incorporated on the surface of zirconium metal slugs. The specimens were exposed to high-temperature 0.34 MPa steam at 1200 and 1300 °C. The primary degradation mechanism for the protective layer was interdiffusion with the zirconium, as opposed to high-temperature oxidation in steam. The FeCrAl layer experienced less degradation and protected the zirconium at 1300 °C for 8 h. Constituents of the Fe-base alloys rapidly diffused into the zirconium and resulted in the formation of various intermetallic layers at the interface and precipitates inside the bulk zirconium. The nature of this interaction for FeCrAl and 310SS has been characterized by use of microscopic techniques as well as computational thermodynamics. Finally, a reactor physics discussion on the applicability of these protective layers in light-water-reactor nuclear fuel structures is offered.

  7. Influence of rare earth additions on the oxidation resistance of chromia forming alloys; Influencia da adicao de terras raras sobre a resistencia a oxidacao de ligas formadoras de cromia

    Energy Technology Data Exchange (ETDEWEB)

    Pillis, Marina Fuser

    1995-12-31

    The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O{sub 2} and AISI 316L+Y{sub 2} O{sub 3} by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O{sub 2} to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O{sub 3}. The isothermal oxidation behavior of rare earth oxide covered

  8. KCl-induced high temperature corrosion of selected commercial alloys. Part I: chromia-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie;

    2015-01-01

    . In the presence of solid KCl, all the alloys showed significant corrosion. Measurement of corrosion extent indicated that alloys EN1.4057, Sanicro 28 and 625 show a better performance compared to the industrial state of the art material TP347HFG under laboratory conditions. An additional test was performed......Laboratory testing of selected chromia-forming alloys was performed to rank the materials and gain further knowledge on the mechanism of KCl-induced high temperature corrosion. The investigated alloys were stainless steels EN1.4021, EN1.4057, EN1.4521, TP347H (coarse-grained), TP347HFG (fine......-grained), Sanicro 28 and the nickel-based alloys 625, 263 and C276. Exposure was performed at 600 °C for 168 h in flowing N2(g)+5%O2(g)+15% H2O(g) (vol.%). Samples were covered with KCl powder prior to exposure. A salt-free exposure was also performed for comparison. Corrosion morphology and products were studied...

  9. Comparison of Short-Term Oxidation Behavior of Model and Commercial Chromia-Forming Ferritic Stainless Steels in Air with Water Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Michael P [ORNL; Keiser, James R [ORNL; More, Karren Leslie [ORNL; Fayek, Mostafa [University of Manitoba, Canada; Walker, Larry R [ORNL; Meisner, Roberta Ann [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Wesolowski, David J [ORNL; Cole, David R [ORNL

    2012-01-01

    A high-purity Fe-20Cr and commercial type 430 ferritic stainless steel were exposed at 700 and 800 C in dry air and air with 10% water vapor (wet air) and characterized by SEM, XRD, STEM, SIMS, and EPMA. The Fe-20Cr alloy formed a fast growing Fe-rich oxide scale at 700 C in wet air after 24 h exposure, but formed a thin chromia scale at 700 C in dry air and at 800 C in both dry air and wet air. In contrast, thin spinel + chromia base scales with a discontinuous silica subscale were formed on 430 stainless steel under all conditions studied. Extensive void formation was observed at the alloy-oxide interface for the Fe-20Cr in both dry and wet conditions, but not for the 430 stainless steel. The Fe-20Cr alloy was found to exhibit a greater relative extent of subsurface Cr depletion than the 430 stainless steel, despite the former's higher Cr content. Depletion of Cr in the Fe-20Cr after 24 h exposure was also greater at 700 C than 800 C. The relative differences in oxidation behavior are discussed in terms of the coarse alloy grain size of the high-purity Fe-20Cr material, and the effects of Mn, Si, and C on the oxide scale formed on the 430 stainless steel.

  10. Influence of a reactive element oxide coating on the high temperature oxidation of chromia-former alloys

    Science.gov (United States)

    Chevalier, S.; Bonnet, G.; Colson, J. C.; Larpin, J. P.

    1998-10-01

    MOCVD technique was used to deposit Nd2O3 coatings on two chromia-formers alloys. Oxidation experiments were performed at 1000 circC under air at atmospheric pressure on uncoated alloys and Nd2O3-coated alloys. The beneficial effects generally ascribed to the reactive elements were confirmed: the oxidation rates were decreased and the adherence of the oxide scales was drastically improved. The reactive element was located at the top of the oxide scale after oxidation. X-ray diffraction measurements identified NdCrO3 as the phase containing the reactive element. This work is compared to a previous study [1] concerning the influence of Nd2O3 on the high temperature oxidation behaviour of a Ti-containing chromia-former alloy in the oxide scale of which a complex phase close to CeTi21O38 was characterized. La technique MOCVD a été utilisée afin de préparer des revêtements de Nd2O3 sur deux alliages chromino-formeurs. Des expériences d'oxydation ont été réalisées à 1000 circC sous air à la pression atmosphérique sur les alliages non revêtus et revêtus de Nd2O3. Les effets bénéfiques généralement attribués aux éléments réactifs ont été confirmés : les vitesses d'oxydation ont été diminuées et l'adhérence des couches d'oxyde a été fortement améliorée. L'élément réactif a été localisé au sommet de la couche d'oxyde. Des analyses par diffraction des rayons X ont permis d'identifier NdCrO3 comme étant la phase contenant l'élément réactif. Ce travail a été comparé avec une étude précédente [1] concernant le comportement en oxydation à haute température d'un acier chromino-formeur contenant du Ti et pour lequel une phase complexe proche de CeTi{21}O{38} avait été caractérisée.

  11. High temperature oxidation of iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, Lars

    2003-06-15

    The high temperature oxidation of the ferritic alloy Fe78Cr22 has been investigated in the present work. The effect of small alloying additions of cerium and/or silicon was also investigated. The alloys were oxidized at 973, 1173 and 1373 K in either air or a hydrogen/argon mixture. The various reaction atmospheres contained between 0.02 and 50% water vapour. The oxide scales formed on the various alloys at 973 K consisted of thin chromia layers. The oxide scales grown on the alloys at 1173 K also consisted of a chromia layer. The microstructure of the chromia scales was found to depend on the reaction atmosphere. The chromia scales grown in hydrogen/argon atmospheres formed oxide whiskers and oxide ridges at the surface of the scales, while the chromia scales grown in air formed larger oxide grains near the surface. This difference in oxide microstructure was due to the vaporization of chromium species from the chromia scales grown in air. Two different growth mechanisms are proposed for the growth of oxide whiskers. The growth rate of the chromia scales was independent of the oxygen activity. This is explained by a growth mechanism of the chromia scales, where the growth is governed by the diffusion of interstitial chromium. The addition of silicon to the iron-chromium alloy resulted in the formation of silica particles beneath the chromia scale. The presence of silicon in the alloy was found to decrease the growth rate of the chromia scale. This is explained by a blocking mechanism, where the silica particles beneath the chromia scale partly block the outwards diffusion of chromium from the alloy to the chromia scale. The addition of cerium to the iron-chromium alloy improved the adhesion of the chromia scale to the alloy and decreased the growth rate of chromia. It was observed that the minimum concentration of cerium in the alloy should be 0.3 at.% in order to observe an effect of the cerium addition. The effect of cerium is explained by the &apos

  12. Mechanisms of oxide layer formation and destruction on a chromia former nickel base alloy in HTR environment; Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR

    Energy Technology Data Exchange (ETDEWEB)

    Rouillard, F

    2007-10-15

    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)

  13. Steam Oxidation and Chromia Evaporation in Ultra-Supercritical Steam Boilers and Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Gordon H. Holcomb

    2009-01-01

    U.S. Department of Energy’s goals include power generation from coal at 60% efficiency, which requires steam conditions of up to 760 °C and 340 atm, so-called ultra-supercritical (USC) conditions. Evaporation of protective chromia scales is expected to be a primary corrosion mechanism. A methodology to calculate Cr evaporation rates from chromia scales was developed and combined with Cr diffusion calculations within the alloy (with a constant flux of Cr leaving the alloy from evaporation) to predict Cr concentration profiles and to predict the time until breakaway oxidation. At the highest temperatures and pressures, the time until breakaway oxidation was predicted to be quite short for the turbine blade, and of concern within the steam pipe and the higher temperature portions of the superheater tube. Alloy additions such as Ti may allow for a reduction in evaporation rate with time, mitigating the deleterious effects of chromia evaporation.

  14. Small-Angle Neutron Scattering and Electron Microscopy Study of the Wet and Dry High-Temperature Oxidation of Alumina- and Chromia- Forming Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot [ORNL; Keiser, James R [ORNL; Brady, Michael P [ORNL; Unocic, Kinga A [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Littrell, Ken [ORNL; Meisner, Roberta Ann [ORNL; Santella, Michael L [ORNL; Wesolowski, David J [ORNL; Cole, David R [ORNL

    2012-01-01

    Foils of T347 stainless steel and a developmental alumina-forming austenitic (AFA) stainless steel were oxidized at 800 C in dry air, air with 10% H2O, and air with 10% D2O. The T347 foils exhibited a transition to rapid Fe-base oxide formation between 24 and 72 h of exposure in H2O and D2O, but exhibited protective Cr-rich oxide formation in dry air. In contrast, only thin, protective Al-rich oxide surfaces were observed for the AFA alloy foils under all conditions studied. Changes in the small angle neutron scattering (SANS) signal were observed for the T347 stainless steel as a function of oxidation time in dry air, attributed to oxide grain growth and porosity formation/partial scale detachment associated with spinel phase at the scale/gas interface. For the AFA alloy, only minor changes in scattering as a result of oxidation time were observed. For both T347 and AFA, similar scattering was observed in dry and wet air (H2O and D2O) exposure. This finding indicates that water vapor exposure did not induce significant morphological changes in the oxide scales (such as increased porosity) in the 5-300 nm size regime accessed by SANS.

  15. Current assisted superplastic forming of titanium alloy

    Directory of Open Access Journals (Sweden)

    Wang Guofeng

    2015-01-01

    Full Text Available Current assisted superplastic forming combines electric heating technology and superplastic forming technology, and can overcome some shortcomings of traditional superplastic forming effectively, such as slow heating rate, large energy loss, low production efficiency, etc. Since formability of titanium alloy at room temperature is poor, current assisted superplastic forming is suitable for titanium alloy. This paper mainly introduces the application of current assisted superplastic forming in the field of titanium alloy, including forming technology of double-hemisphere structure and bellows.

  16. Chromia refractory brick with carbon treatment

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, James P.; Kwong, Kyei-Sing

    2017-03-21

    The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250.degree. C. and 1575.degree. C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.-4 and 10.sup.-10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.

  17. Development of Cast Alumina-Forming Austenitic Stainless Steels

    Science.gov (United States)

    Muralidharan, G.; Yamamoto, Y.; Brady, M. P.; Walker, L. R.; Meyer, H. M., III; Leonard, D. N.

    2016-09-01

    Cast Fe-Ni-Cr chromia-forming austenitic stainless steels with Ni levels up to 45 wt.% are used at high temperatures in a wide range of industrial applications that demand microstructural stability, corrosion resistance, and creep strength. Although alumina scales offer better corrosion protection at these temperatures, designing cast austenitic alloys that form a stable alumina scale and achieve creep strength comparable to existing cast chromia-forming alloys is challenging. This work outlines the development of cast Fe-Ni-Cr-Al austenitic stainless steels containing about 25 wt.% Ni with good creep strength and the ability to form a protective alumina scale for use at temperatures up to 800-850°C in H2O-, S-, and C-containing environments. Creep properties of the best alloy were comparable to that of HK-type cast chromia-forming alloys along with improved oxidation resistance typical of alumina-forming alloys. Challenges in the design of cast alloys and a potential path to increasing the temperature capability are discussed.

  18. Development of Cast Alumina-Forming Austenitic Stainless Steels

    Science.gov (United States)

    Muralidharan, G.; Yamamoto, Y.; Brady, M. P.; Walker, L. R.; Meyer, H. M., III; Leonard, D. N.

    2016-11-01

    Cast Fe-Ni-Cr chromia-forming austenitic stainless steels with Ni levels up to 45 wt.% are used at high temperatures in a wide range of industrial applications that demand microstructural stability, corrosion resistance, and creep strength. Although alumina scales offer better corrosion protection at these temperatures, designing cast austenitic alloys that form a stable alumina scale and achieve creep strength comparable to existing cast chromia-forming alloys is challenging. This work outlines the development of cast Fe-Ni-Cr-Al austenitic stainless steels containing about 25 wt.% Ni with good creep strength and the ability to form a protective alumina scale for use at temperatures up to 800-850°C in H2O-, S-, and C-containing environments. Creep properties of the best alloy were comparable to that of HK-type cast chromia-forming alloys along with improved oxidation resistance typical of alumina-forming alloys. Challenges in the design of cast alloys and a potential path to increasing the temperature capability are discussed.

  19. Oxidation of two-phase Cu-Cr alloys with different microstructures

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The oxidation of PM Cu-50Cr, MA Cu-40Cr and MS Cu-40Cr alloys at 800  ℃ in 0.1  MPa O2 was studied. The most important difference of their oxidation behaviors is the formation of an exclusive chromia scale on the surface of the MS Cu-40Cr alloy and a continuous chromia layer beneath an outer CuO layer corresponding MA Cu-40Cr alloy, while a complex scale composing of CuO, Cu2O, Cu2Cr2O4 and Cr2O3 formed on the PM Cu-50Cr alloy. This result implies that alloy microstructure affects their oxidation behaviors largely. Microcrystalline structure provides numerous diffusion paths for reactive component chromium, shorter diffusion distance and rapid dissolution of Cr-riched second phase. All these favor the exclusive formation of the most stable oxide.

  20. Ultrahigh temperature intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  1. Forming of aluminium alloy friction stir welds

    Science.gov (United States)

    Bruni, Carlo

    2016-10-01

    The present paper aims at investigating, through analytical models, numerical models and experiments, the effect of the warm deformation phase, realised with an in temperature upsetting, on the weld previously performed by friction stir lap welding on aluminium alloy blanks. The investigation allows to show the deformation zones after upsetting that determine the homogenisation of the weld section. The analytical model allows to relate the friction factor with the upsetting load. The presence on the weld of not elevated friction factor values determines the deformation and localisation levels very useful for the weld. Such methodology allows to improve the weld itself with the forming phase.

  2. Alloy substantially free of dendrites and method of forming the same

    Science.gov (United States)

    de Figueredo, Anacleto M.; Apelian, Diran; Findon, Matt M.; Saddock, Nicholas

    2009-04-07

    Described herein are alloys substantially free of dendrites. A method includes forming an alloy substantially free of dendrites. A superheated alloy is cooled to form a nucleated alloy. The temperature of the nucleated alloy is controlled to prevent the nuclei from melting. The nucleated alloy is mixed to distribute the nuclei throughout the alloy. The nucleated alloy is cooled with nuclei distributed throughout.

  3. Reference Alloy Waste Form Fabrication and Initiation of Reducing Atmosphere and Reductive Additives Study on Alloy Waste Form Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    S.M. Frank; T.P. O' Holleran; P.A. Hahn

    2011-09-01

    This report describes the fabrication of two reference alloy waste forms, RAW-1(Re) and RAW-(Tc) using an optimized loading and heating method. The composition of the alloy materials was based on a generalized formulation to process various proposed feed streams resulting from the processing of used fuel. Waste elements are introduced into molten steel during alloy fabrication and, upon solidification, become incorporated into durable iron-based intermetallic phases of the alloy waste form. The first alloy ingot contained surrogate (non-radioactive), transition-metal fission products with rhenium acting as a surrogate for technetium. The second alloy ingot contained the same components as the first ingot, but included radioactive Tc-99 instead of rhenium. Understanding technetium behavior in the waste form is of particular importance due the longevity of Tc-99 and its mobility in the biosphere in the oxide form. RAW-1(Re) and RAW-1(Tc) are currently being used as test specimens in the comprehensive testing program investigating the corrosion and radionuclide release mechanisms of the representative alloy waste form. Also described in this report is the experimental plan to study the effects of reducing atmospheres and reducing additives to the alloy material during fabrication in an attempt to maximize the oxide content of waste streams that can be accommodated in the alloy waste form. Activities described in the experimental plan will be performed in FY12. The first aspect of the experimental plan is to study oxide formation on the alloy by introducing O2 impurities in the melt cover gas or from added oxide impurities in the feed materials. Reducing atmospheres will then be introduced to the melt cover gas in an attempt to minimize oxide formation during alloy fabrication. The second phase of the experimental plan is to investigate melting parameters associated with alloy fabrication to allow the separation of slag and alloy components of the melt.

  4. Property measurements on spray formed Si-Al alloys

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-guang; XIONG Bai-qing; ZHANG Yong-an; LIU Hong-wei; WANG Feng; ZHU Bao-hong

    2007-01-01

    A novel Si-Al alloy was prepared by spray forming process for electronic packaging. Property measurements on spray-formed Si-Al alloys after hot pressing were carried out. The results indicate that the alloys (Si-(30%-40%)Al) have advantageous physical and mechanical characteristics, including low coefficient of thermal expansion (6.9×10-6-8.7×10-6/K), high thermal conductivity (118-127 W/(m·K)), low density (2.421×103-2.465×103 kg/m3), high ultimate flexural strength (180-220 MPa) and Brinell hardness (162-261). The alloys are easy to machine to tight tolerances using standard machine tools and they can be electroplated with gold finishes and soldered with Sn-Pb alloy without any difficulty.

  5. Long-Term Cyclic Oxidation Behavior of Wrought Commercial Alloys at High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bingtao Li

    2003-08-05

    The oxidation resistance of a high-temperature alloy is dependent upon sustaining the formation of a protective scale, which is strongly related to the alloying composition and the oxidation condition. The protective oxide scale only provides a finite period of oxidation resistance owing to its eventual breakdown, which is especially accelerated under thermal cycling conditions. This current study focuses on the long-term cyclic oxidation behavior of a number of commercial wrought alloys. The alloys studied were Fe- and Ni-based, containing different levels of minor elements, such as Si, Al, Mn, and Ti. Oxidation testing was conducted at 1000 and 1100 C in still air under both isothermal and thermal cycling conditions (1-day and 7-days). The specific aspects studied were the oxidation behavior of chromia-forming alloys that are used extensively in industry. The current study analyzed the effects of alloying elements, especially the effect of minor element Si, on cyclic oxidation resistance. The behavior of oxide scale growth, scale spallation, subsurface changes, and chromium interdiffusion in the alloy were analyzed in detail. A novel model was developed in the current study to predict the life-time during cyclic oxidation by simulating oxidation kinetics and chromium interdiffusion in the subsurface of chromia-forming alloys.

  6. Superplastic forming gas pressure of titanium alloy bellows

    Institute of Scientific and Technical Information of China (English)

    王刚; 张凯锋; 陈军; 阮雪榆

    2004-01-01

    The complex superplastic forming (SPF) technology applying gas pressure and compressive axial load is an advanced forming method for titanium alloy bellows, whose forming process consists of the three main forming phases namely bulging, clamping and calibrating phase. The influence of forming gas pressure in various phases on the forming process was analyzed and the models of forming gas pressure for bellows were derived according to the thin shell theory and the plasticity deformation theory. Using the model values, taking a two-convolution DN250 Ti6Al-4V titanium alloy bellows as an example, a series of superplastic forming tests were performed to evaluate the influence of the variation of forming gas pressure on the forming process. According to the experimental results these models were corrected to make the forming gas pressures prediction more accurate.

  7. AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

    DEFF Research Database (Denmark)

    1997-01-01

    An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...... additive. This method makes it possible to deposit nickel, cobalt, nickel or cobalt platings without internal stresses....

  8. Local stress determination in chromia-former thanks to micro-Raman spectroscopy: A way to investigate spontaneous delamination processes

    Science.gov (United States)

    Guerain, M.; Goudeau, P.; Panicaud, B.; Grosseau-Poussard, J. L.

    2013-02-01

    Spontaneous delamination process for α-Cr2O3 thermal oxide films growing on NiCr-30 alloys is studied thanks to micro Raman spectroscopy. In particular, stress maps are performed through and around buckles developed on chromia films. Depending on the cooling rate at the end of the oxidation process, different buckle types appear which are investigated. Associated residual stress distribution clearly evidences the stress release field. In addition, geometrical features are determined for the different buckle types, and from comparison with modelling describing buckle formation and propagation, it is possible to get the interface toughness distribution.

  9. Thermodynamic simulation of the effect of slag chemistry on the corrosion behavior of alumina-chromia refractory

    Institute of Scientific and Technical Information of China (English)

    Shi-xian Zhao; Bin-li Cai; Hong-gang Sun; Gang Wang; Hong-xia Li; and Xiao-yan Song

    2016-01-01

    The corrosion behavior of alumina–chromia refractory against two kinds of industrial slags (coal slag and iron smelting slag) at 1550°C was investigated via thermodynamic simulations. In the proposed simulation model, the initial slag first attacks the matrix and sur-face aggregates and subsequently attacks the inner aggregates. The simulation results indicate that the slag chemistry strongly affects the phase formation and corrosion behavior of the refractory brick. Greater amounts of alumina were dissolved and spinel solid phases formed when the brick interacted with iron smelting slag. These phenomena, as well as the calculated lower viscosity, may lead to much deeper penetration than that exhibited by coal slag and to more severe corrosion compared to that induced by coal slag. The thermodynamic calcula-tions well match the experimental observations, demonstrating the efficiency of the proposed simulation model for evaluating the corrosion behavior of alumina–chromia refractory.

  10. Superplastic Forming and Diffusion Bonding of Titanium Alloys

    Directory of Open Access Journals (Sweden)

    A. K. Ghosh

    1986-04-01

    Full Text Available New and advanced fabrication methods for titanium components are emerging today to replace age-old fabrication processes and reduce component cost. Superplastic forming and diffusion bonding are two such advanced fabrication technologies which when applied individually or in combination can provide significant cost and weight benefits and a rather broad manufacturing technology base. This paper briefly reviews the state of understanding of the science and technology of super plastic forming of titanium alloys, and their diffusion bonding capability. Emphasis has been placed on the metallurgy of superplastic flow in two phase titanium alloys, the microstructural and external factors which influence this behaviour.

  11. NUMERICAL SIMULATION FOR FORMED PROJECTILE OF DEPLETED URANIUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    宋顺成; 高平; 才鸿年

    2003-01-01

    The numerical simulation for forming projectile of depleted uranium alloy with the SPH ( Smooth Particle Hydrodynamic ) algorithm was presented. In the computations the artificial pressures of detonation were used, i. e. , the spatial distribution and time distribution were given artificially. To describe the deformed behaviors of the depleted uranium alloy under high pressure and high strain rate, the Johnson-Cook model of materials was introduced. From the numerical simulation the formed projectile velocity,projectile geometry and the minimum of the height of detonation are obtained.

  12. Simulation study for atomic size and alloying effects during forming processes of amorphous alloys

    Institute of Scientific and Technical Information of China (English)

    ZHENG Caixing; LIU Rangsu; PENG Ping; ZHOU Qunyi

    2004-01-01

    A molecular dynamics (MD) simulation study has been performed for the solidification processes of two binary liquid alloys Ag6Cu4 and CuNi by adopting the quantum Sutton-Chen many-body potentials. By analyzing bond-types, it is demonstrated that at the cooling rate of 2×1012K/s, the CuNi forms fcc crystal structures, while the Ag6Cu4 forms amorphous structures. The original reason is that the atomic radius ratio (1.13) of the CuAg is bigger than that (1.025) of the CuNi. This shows that the atomic size difference is indeed the main factor for forming amorphous alloys. Moreover, for Ag60Cu40,corresponding to the deep eutectic point in the phase diagram, it forms amorphous structure easily. This confirms that as to the forming tendency and stability of amorphous alloys, the alloying effect plays a key role. In addition, having analyzed the transformation of microstructures by using the bond-type index and cluster-type index methods, not only the key role of the icosahedral configuration to the formation and stability of amorphous alloys can be explained, but also the solidification processes of liquid metals and the characteristics of amorphous structures can be further understood.

  13. Forming analysis and application for aluminum-alloy material

    Institute of Scientific and Technical Information of China (English)

    Wei Yuansheng

    2012-01-01

    The increase in car ownership brought about by energy shortages, and environmental crises became more acute. The most effective way to achieve energy saving and emission reduction of car is to improve engine efficiency. In addition to that, lightweight body is the key. Aluminum, magnesium alloy as significant materials of lightweight, and the application amount in the car body is a significant upward trend. However, there is high cost of material, with im- mature applied technology and a series of bottleneck problems. All of them affect general application of lightweight mate- rials. This paper focuses on forming process issues for aluminum, magnesium alloy and the solutions to achieve.

  14. Incremental forming of aluminium alloys in cryogenic environment

    Science.gov (United States)

    Vanhove, Hans; Mohammadi, Amirahmad; Duflou, Joost R.

    2016-10-01

    Incremental Sheet Forming processes suffer from stringent forming limits, restricting the range of producible geometries. Through in-process cooling of the sheet to cryogenic level, this paper explores the potential of altering material properties benefiting the formability and residual hardness of different aluminium alloys. Global cooling of aluminium sheets with liquid nitrogen and dry ice allows to reach temperatures of 78K and 193K respectively. Extended with experiments at room temperature (293K), these tests form a base for comparison of surface quality, formability and residual hardness. As an aluminium alloy commonly used for its high strength to weight ratio, but suffering from limited formability compared to draw-quality steels, AA5083-H111 is of interest for cryogenic treatment. AA1050-H24 is included in the test campaign as a base for commercially pure aluminium.

  15. Low-Temperature Forming of Beta Titanium Alloys

    Science.gov (United States)

    Kaneko, R. S.; Woods, C. A.

    1983-01-01

    Low cost methods for titanium structural fabrication using advanced cold-formable beta alloys were investigated for application in a Mach 2.7 supersonic cruise vehicle. This work focuses on improving processing and structural efficiencies as compared with standard hot formed and riveted construction of alpha-beta alloy sheet structure. Mechanical property data and manufacturing parameters were developed for cold forming, brazing, welding, and processing Ti-15V-3Cr-3Sn-3Al sheet, and Ti-3Al-8V-6Cr-4Zr on a more limited basis. Cost and structural benefits were assessed through the fabrication and evaluation of large structural panels. The feasibility of increasing structural efficiency of beta titanium structure by selective reinforcement with metal matrix composite was also explored.

  16. QuikForm: Intelligent deformation processing of structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier, R.J.; Wellman, G.W.

    1994-09-01

    There currently exists a critical need for tools to enhance the industrial competitiveness and agility of US industries involved in deformation processing of structural alloys. In response to this need, Sandia National Laboratories has embarked upon the QuikForm Initiative. The goal of this program is the development of computer-based tools to facilitate the design of deformation processing operations. The authors are currently focusing their efforts on the definition/development of a comprehensive system for the design of sheet metal stamping operations. The overall structure of the proposed QuikForm system is presented, and the focus of their thrust in each technical area is discussed.

  17. Engineered Coatings for Ni Alloys in High Temperature Reactors

    Science.gov (United States)

    Clark, Elizabeth A.; Yang, James Y.; Kumar, Deepak; Was, Gary S.; Levi, Carlos G.

    2013-02-01

    Alloy 617 is a candidate material for the intermediate heat exchanger of the He-cooled very high temperature reactor. At target temperatures ≥1223 K (950 °C), low level impurities in the gas stream may cause carburization, decarburization, and/or oxidation of 617 with deleterious effects on its mechanical properties. The chromia scale formed naturally by 617 does not provide adequate protection in the expected environment. Alpha alumina offers a greater potential as an effective diffusion barrier with superior stability, but it requires modification of the alloy surface. This work explores two approaches to surface modification based on aluminizing, either alone or in combination with FeCrAlY cladding, followed by pre-oxidation to form alpha alumina. Both approaches yield coatings with promising diffusional stability on alloy 617. Initial corrosion studies in impure He environments reveal that the alpha alumina is stable and protects the underlying substrate in both carburizing and decarburizing environments.

  18. Damage percolation during stretch flange forming of aluminum alloy sheet

    Science.gov (United States)

    Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

    2005-12-01

    A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

  19. Tribological Behaviour of the Ceramic Coating Formed on Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; ZHOU Hai; CHEN Qiang; GE Yuanjing; LV Fanxiu

    2007-01-01

    Micro-arc oxidation is a recently developed surface treatment technology under anodic oxidation. Through micro-arc oxidation, a ceramic coating is directly formed on the surface of magnesium alloy, by which its surface property is significantly improved. In this paper, a dense ceramic oxide coating was prepared on an AZ31 magnesium alloy by micro-arc oxidation in a NaOH-Na2SiO3-NaB4O7-(NaPO3)6 electrolytic solution. Micro-structure, surface morphology and phase composition were analysed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The tribological behavior of the micro-arc oxidation ceramic coating under dry sliding against GCrl5 steel was evaluated on a ball-on-disc test rig. The results showed that the AZ31 alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface micro-arc oxidation ceramic coating experienced much abated adhesion wear and scuffing under the same testing conditions. The micro-arc oxidation ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel.

  20. Microstructurally Controlled Mechanical Properties of Al-Mg-Si Alloys for Warm Forming Applications

    NARCIS (Netherlands)

    Ghosh, M.

    2011-01-01

    Owing to their light weight and excellent corrosion resistance the use of aluminium alloys in automotive industries is increasing progressively. However, aluminium alloys remain mainly handicapped by poor room temperature formability compared to steel. Increasing temperature during forming, but stil

  1. Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101:Insight into chromium species on activity and selectivity

    Institute of Scientific and Technical Information of China (English)

    Huahua Zhao; Huanling Song; Zhichao Miao; Lingjun Chou

    2014-01-01

    Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCrAl-I1 with largest specific surface area of 198 m2·g−1 prepared with aluminium isopropoxide (Al(i-OC3H7)3) by ultrasonic im-pregnation method. However, the catalyst KCrAl-I2 synthesized by stirring impregnation possessed crystallineα-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich CrxAl2−xO3 solid solutions, designated as CrAl-I and CrAl-II phase, were formed over the catalysts KCrAl-I3 (prepared by Al(i-OC3H7)3 with nitric acid regulation), KCrAl-C4 (prepared by aluminium chloride hexahydrate) and KCrAl-N5 (prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCrAl-I1 exhibited the high isobutane con-version due to its highly dispersed chromium species. However, KCrAl-I3, KCrAl-C4 and KCrAl-N5 showed the higher isobutene selectivity (95.2%−96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.

  2. Corrosion of refractory alloys induced by sodium sulphate in simulated low oxygen potential atmospheres of the BTL plants

    Energy Technology Data Exchange (ETDEWEB)

    Couture, Ludovic [Grenoble Univ., Saint Martin d' Heres (France). SIMaP; IFP, Solaize (France). Materials Dept.; Galerie, Alain; Wouters, Yves [Grenoble Univ., Saint Martin d' Heres (France). SIMaP; Grosjean, Francois; Kittel, Jean; Ropital, Francois [IFP, Solaize (France). Materials Dept.

    2010-07-01

    BTL (biomass to liquid) is an innovative process to synthesize second generation bio-gasoline from wood and farm residues. In the present work, the effect of sodium sulphate on the high-temperature corrosion at 900 C of two refractory alloys, the chromia-forming Haynes {sup registered} HR-120 and the alumina-forming Haynes {sup registered} 214 in a simulated process atmosphere CO/H{sub 2}/CO{sub 2} (45/45/10% vol.), was investigated for durations up to 96 h. (orig.)

  3. Effects of Alloying Element Ca on the Corrosion Behavior and Bioactivity of Anodic Films Formed on AM60 Mg Alloys

    Directory of Open Access Journals (Sweden)

    Anawati Anawati

    2016-12-01

    Full Text Available Effects of alloying element Ca on the corrosion behavior and bioactivity of films formed by plasma electrolytic oxidation (PEO on AM60 alloys were investigated. The corrosion behavior was studied by conducting electrochemical tests in 0.9% NaCl solution while the bioactivity was evaluated by soaking the specimens in simulated body fluid (SBF. Under identical anodization conditions, the PEO film thicknesses increased with increasing Ca content in the alloys, which enhanced the corrosion resistance in NaCl solution. Thicker apatite layers grew on the PEO films of Ca-containing alloys because Ca was incorporated into the PEO film and because Ca was present in the alloys. Improvement of corrosion resistance and bioactivity of the PEO-coated AM60 by alloying with Ca may be beneficial for biodegradable implant applications.

  4. Durability and degradation of HT9 based alloy waste forms with variable Ni and Cr content

    Energy Technology Data Exchange (ETDEWEB)

    Olson, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-12-31

    Short-term electrochemical and long-term hybrid electrochemical corrosion tests were performed on alloy waste forms in reference aqueous solutions that bound postulated repository conditions. The alloy waste forms investigated represent candidate formulations that can be produced with advanced electrochemical treatment of used nuclear fuel. The studies helped to better understand the alloy waste form durability with differing concentrations of nickel and chromium, species that can be added to alloy waste forms to potentially increase their durability and decrease radionuclide release into the environment.

  5. Oxidation of High-temperature Alloy Wires in Dry Oxygen and Water Vapor

    Science.gov (United States)

    Opila, Elizabeth J.; Lorincz, Jonathan A.; DeMange, Jeffrey J.

    2004-01-01

    Small diameter wires (150 to 250 microns) of the high temperature alloys Haynes 188, Haynes 230, Haynes 230, Haynes 214, Kanthal Al and PM2000 were oxidized at 1204 C in dry oxygen or 50% H2O /50% O2 for 70 Hours. The oxidation kinetics were monitored using a thermogravimetric technique. Oxide phase composition and morphology of the oxidized wires were determined by X-ray diffraction,field emission scanning electron microscopy, and energy dispersive spectroscopy. The alumina-forming alloys, Kanthal Al and PM2000, out-performed the chromia-forming alloys under this conditions. PM2000 was recommended as the most promising candidate for advanced hybrid seal applications for space reentry control surface seals or hypersonic propulsion system seals. This study also demonstrated that thermogravimetric analysis of small diameter wires is a powerful technique for the study of oxide volatility, oxide adherence, and breakaway oxidation.

  6. Numerical simulation of high speed incremental forming of aluminum alloy

    Science.gov (United States)

    Giuseppina, Ambrogio; Teresa, Citrea; Luigino, Filice; Francesco, Gagliardi

    2013-12-01

    In this study, an innovative process is analyzed with the aim to satisfy the industrial requirements, such as process flexibility, differentiation and customizing of products, cost reduction, minimization of execution time, sustainable production, etc. The attention is focused on incremental forming process, nowadays used in different fields such as: rapid prototyping, medical sector, architectural industry, aerospace and marine, in the production of molds and dies. Incremental forming consists in deforming only a small region of the workspace through a punch driven by a NC machine. SPIF is the considered variant of the process, in which the punch gives local deformation without dies and molds; consequently, the final product geometry can be changed by the control of an actuator without requiring a set of different tools. The drawback of this process is its slowness. The aim of this study is to assess the IF feasibility at high speeds. An experimental campaign will be performed by a CNC lathe with high speed to test process feasibility and the influence on materials formability mainly on aluminum alloys. The first results show how the material presents the same performance than in conventional speed IF and, in some cases, better material behavior due to the temperature field. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process substantially confirming experimental evidence.

  7. THE FORMING OF MAGNESIUM ALLOY FORGINGS FOR AIRCRAFT AND AUTOMOTIVE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Anna Dziubińska

    2016-09-01

    Full Text Available The paper presents the theoretical and technological aspects of forming magnesium alloy parts for aircraft and automotive applications. The main applications of magnesium alloys in the aircraft and automotive industries are discussed. In addition, the forging technology for magnesium alloys is generally described, with a particular emphasis on wrought alloys. A brief outline of the state of the art in the forging of magnesium alloys is given based on a survey of the specialist literature and the results of previous research by the authors.

  8. Corrosion of high temperature alloys in solar salt at 400, 500, and 680ÀC.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-09-01

    Corrosion tests at 400, 500, and 680ÀC were performed using four high temperature alloys; 347SS, 321SS In625, and HA230. Molten salt chemistry was monitored over time through analysis of nitrite, carbonate, and dissolved metals. Metallography was performed on alloys at 500 and 680ÀC, due to the relatively thin oxide scale observed at 400ÀC. At 500ÀC, corrosion of iron based alloys took the form of chromium depletion and iron oxides, while nickel based alloys also had chromium depletion and formation of NiO. Chromium was detected in relatively low concentrations at this temperature. At 680ÀC, significant surface corrosion occurred with metal losses greater than 450microns/year after 1025hours of exposure. Iron based alloys formed complex iron, sodium, and chromium oxides. Some data suggests grain boundary chromium depletion of 321SS. Nickel alloys formed NiO and metallic nickel corrosion morphologies, with HA230 displaying significant internal oxidation in the form of chromia. Nickel alloys both exhibited worse corrosion than iron based alloys likely due to preferential dissolution of chromium, molybdenum, and tungsten.

  9. Dual-Alloy Disks are Formed by Powder Metallurgy

    Science.gov (United States)

    Harf, F. H.; Miner, R. V.; Kortovich, C. S.; Marder, J. M.

    1982-01-01

    High-performance disks have widely varying properties from hub to rim. Dual property disk is fabricated using two nickel-base alloys, AF-115 for rim and Rene 95 for hub. Dual-alloy fabrication may find applications in automobiles, earth-moving equipment, and energy conversion systems as well as aircraft powerplants. There is potential for such applications as shafts, gears, and blades.

  10. Laser rapid forming of low cost hydride-dehydride titanium alloy powder

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing; ZHANG Feng-ying; LIN Xin; TAN Hua; HUANG Wei-dong

    2006-01-01

    Low cost hydride-dehydride (HDH) Ti-6Al-4V (Ti-64) alloy powder was employed to investigate the metallurgical quality and mechanical properties of laser formed samples. With appropriate control of the laser forming processing parameters and the loose density of HDH powder, two kinds of defect, i.e. porosity and ill-bonding, can be avoided. Rare earth Nd powder was added to HDH Ti-64 powder to purify laser formed alloy. The results show that with a few additive of Nd, the microstructure of laser formed alloy changes from Widmanst-tten morphology to a basket weave microstructure. Accordingly an appropriate addition of Nd is effective to improve both the strength and ductility of laser formed HDH Ti-64 alloy. The values of tensile test meet the wrought specification with the content of Nd ranging from 0.1%-0.2%(mass fraction).

  11. Stress Relaxation Behavior and Springback Equation of 7050 Aluminum Alloys During Age-forming Process

    Directory of Open Access Journals (Sweden)

    REN Wei-wei

    2016-09-01

    Full Text Available The stress relaxation behavior and springback equation of 7050 aluminum alloys during the age-forming process were studied through self-designed uniaxial tension device. The results show that in traditional aging temperature, the stress relaxation curve of 7050 aluminum alloys exhibits a classical logarithmic decrement curve. The stress relaxation process can be divided into three stages, which are the initial stress decayed fast stage, the subsequent stress slowly decayed stage and the stress constantly maintained stage, respectively. Stress relaxation limit of 7050 aluminum alloys decreases with increasing aging temperature. The threshold stress presents during the stress relaxation process due to the interaction between precipitation behavior and dislocation creep of 7050 aluminum alloys. The stress relaxation equation of 7050 aluminum alloys is obtained through resolving the feature and Taylor equation of relaxation process, and using the stress relaxation equation can precisely predict the springback of workpiece after age-forming.

  12. Effect of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation.The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.

  13. Density and glass forming ability in amorphous atomic alloys: The role of the particle softness

    Science.gov (United States)

    Douglass, Ian; Hudson, Toby; Harrowell, Peter

    2016-04-01

    A key property of glass forming alloys, the anomalously small volume difference with respect to the crystal, is shown to arise as a direct consequence of the soft repulsive potentials between metals. This feature of the inter-atomic potential is demonstrated to be responsible for a significant component of the glass forming ability of alloys due to the decrease in the enthalpy of fusion and the associated depression of the freezing point.

  14. 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.

  15. Electrical resistivity of NaPb compound-forming liquid alloy using ab initio pseudopotentials

    Indian Academy of Sciences (India)

    Anil Thakur; N S Negi; P K Ahluwalla

    2005-08-01

    The study of electrical resistivity of compound-forming liquid alloy, NaPb, is presented as a function of concentration. Hard sphere diameters of Na and Pb are obtained through the interionic pair potentials evaluated using Troullier and Martins ab initio pseudopotential, which have been used to calculate the partial structure factors (). Considering the liquid alloy to be a ternary mixture, Ziman formula, modified for complex formation has been used for calculating resistivity of binary liquid alloys. Form factors are calculated using ab initio pseudopotentials. The results suggest that Ziman formalism, when used with ab initio pseudopotentials, are quite successful in explaining the electrical resistivity data of compound-forming binary liquid alloys.

  16. On the origin of bulk glass forming ability in Cu-Hf, Zr alloys

    Science.gov (United States)

    Ristić, Ramir; Zadro, Krešo; Pajić, Damir; Figueroa, Ignacio A.; Babić, Emil

    2016-04-01

    Understanding the formation of bulk metallic glasses (BMG) in metallic systems and finding a reliable criterion for selection of BMG compositions are among the most important issues in condensed-matter physics and material science. Using the results of magnetic susceptibility measurements performed on both amorphous and crystallized Cu-Hf alloys (30-70 at% Cu) we find a correlation between the difference in magnetic susceptibilities of corresponding glassy and crystalline alloys and the variation in the glass forming ability (GFA) in these alloys. Since the same correlation can be inferred from data for the properties associated with the electronic structure of Cu-Zr alloys, it seems quite general and may apply to other glassy alloys based on early and late transition metals. This correlation is plausible from the free-energy considerations and provides a simple way to select the compositions with high GFA.

  17. Effect of Aging Treatments on the Mechanical and Corrosive Behaviors of Spray-Formed 7075 Alloy

    Science.gov (United States)

    Su, Rui-ming; Qu, Ying-dong; Li, Rong-de

    2014-11-01

    Mechanical properties, microstructure, exfoliation corrosion (EXCO), and intergranular corrosion (IGC) behaviors of the spray-formed 7075 aluminum alloy after T6, T73, retrogression (R), and re-aging (RRA) treatment, respectively, were studied by using tensile tester, transmission electron microscope, and scanning electron microscope. The results show that the T6 process can increase the ultimate tensile strength (UTS) up to 760 MPa, while it decreases the elongation, the EXCO, and the IGC resistance of the alloy. The T73 process can improve elongation, the EXCO, and the IGC resistance of the alloy. The corrosion resistance of the alloy can also be improved by R and RRA processes with retrogression times increase. The tiny precipitated phases distributed homogeneously in the matrix can increase the UTS. The close-connected discrete grain boundary phases (GBP) and the narrow precipitate free zones (PFZ) will lower the elongation, the EXCO, and the IGC resistance of the alloy. Contrarily, the discrete GBP and wide PFZ can improve the elongation, the EXCO, and the IGC resistance of the alloy. The EXCO and the IGC behaviors for the spray-formed 7075 alloy after different aging treatments have been established according to the standards of ASTM G34-2001 (2007) and ASTM G110-1992 (2009).

  18. System and method of forming nanostructured ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dial, Laura Cerully; DiDomizio, Richard; Alinger, Matthew Joseph; Huang, Shenyan

    2016-07-26

    A system for mechanical milling and a method of mechanical milling are disclosed. The system includes a container, a feedstock, and milling media. The container encloses a processing volume. The feedstock and the milling media are disposed in the processing volume of the container. The feedstock includes metal or alloy powder and a ceramic compound. The feedstock is mechanically milled in the processing volume using metallic milling media that includes a surface portion that has a carbon content less than about 0.4 weight percent.

  19. Nickel Alloy Primary Water Bulk Surface and SCC Corrosion Film Analytical Characterization and SCC Mechanistic Implications

    Energy Technology Data Exchange (ETDEWEB)

    Morton, D.; Lewis, N.; Hanson, M.; Rice, S.; Sanders, P.

    2007-04-18

    Alloy 600 corrosion coupon tests were performed: (1) to quantify the temperature dependency of general corrosion and (2) to characterize the composition and structure of bulk surface corrosion films for comparison with ongoing primary water SCC (PWSCC) crack tip corrosion film analyses. Results suggest that the thermal activation energy of Alloy 600 corrosion is consistent with the thermal activation energy of nickel alloy PWSCC. Analytical investigations of the structure and composition of Alloy 600 bulk surface corrosion oxides revealed a duplex (inner and outer) oxide layer structure. The outer layer is discontinuous and comprised of relatively large (1 to 3 {micro}m) nickel ferrite crystals and smaller ({approx}0.1 {micro}m) chromium containing nickel ferrite crystals. The inner layer consists of a relatively continuous chromite spinel (major phase) and chromia (Cr{sub 2}O{sub 3} minor phase) which formed through non-selective oxidation. Chromia and dealloyed Alloy 600 (highly Ni enriched metal) were only observed at 337 C (640 F) and only along the boundaries of deformation induced fine grains and subcells. Specimens having deformation free surfaces exhibited continuous uniform inner chromite spinel oxide layers. Specimens with machining induced surface deformation produced non-uniform inner layer oxides (chromite spinel, Cr{sub 2}O{sub 3} and unoxidized material). PWSCC crack tip oxides, in contrast, were fine grain (no duplex structure) and consisted of both chromium rich spinels and ''NiO'' structure oxides. Generally, nickel rich oxides were more abundant under more oxidized conditions (reduced coolant hydrogen) and spinel rich crack tip oxides were favored under more reducing conditions (increased coolant hydrogen). Bulk surface corrosion film thickness did not correlate with observed SCC growth rates. These results suggest that corrosion is not the rate controlling step of PWSCC but rather that PWSCC and corrosion have a common rate

  20. Cyclic Oxidation of High-Temperature Alloy Wires in Air

    Science.gov (United States)

    Reigel, Marissa M.

    2004-01-01

    High-temperature alloy wires are proposed for use in seal applications for future re-useable space vehicles. These alloys offer the potential for improved wear resistance of the seals. The wires must withstand the high temperature environments the seals are subjected to as well as maintain their oxidation resistance during the heating and cooling cycles of vehicle re-entry. To model this, the wires were subjected to cyclic oxidation in stagnant air. of this layer formation is dependent on temperature. Slow growing oxides such as chromia and alumina are desirable. Once the oxide is formed it can prevent the metal from further reacting with its environment. Cyclic oxidation models the changes in temperature these wires will undergo in application. Cycling the temperature introduces thermal stresses which can cause the oxide layer to break off. Re-growth of the oxide layer consumes more metal and therefore reduces the properties and durability of the material. were used for cyclic oxidation testing. The baseline material, Haynes 188, has a Co base and is a chromia former while the other two alloys, Kanthal A1 and PM2000, both have a Fe base and are alumina formers. Haynes 188 and Kanthal A1 wires are 250 pm in diameter and PM2000 wires are 150 pm in diameter. The coiled wire has a total surface area of 3 to 5 sq cm. The wires were oxidized for 11 cycles at 1204 C, each cycle containing a 1 hour heating time and a minimum 20 minute cooling time. Weights were taken between cycles. After 11 cycles, one wire of each composition was removed for analysis. The other wire continued testing for 70 cycles. Post-test analysis includes X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) for phase identification and morphology.

  1. Gas-pressure forming of an AlMg-alloy sheet at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rauscher, B.; Goesling, M.; Homberg, W.; Kleiner, M. [Dortmund Univ. (DE). Inst. of Forming Technology and Lightweight Construction (IUL)

    2005-12-01

    Forming of automotive leightweight parts using aluminium offers numerous advantages. Compared to other wrought aluminium alloys, in particular AlMg-alloys generally show a good formability which is favourable for the production of complex parts. However, forming of Mg-containing alloys at room temperature leads to yielding patterns preventing their implementation for class-A-surface applications. Furthermore, the formability of steel still exceeds that of AlMg-alloys at room temperature. Thus, in the present study, sheet metal forming is applied at a temperature range that is typical for warm forming. It is supposed to profit from the advantages of warm forming like high achievable strains and improved surface quality of the formed part, while not having the disadvantages of long production times and high energy consumption, which is correlated with superplastic forming. Applying fluid-based sheet metal forming in this paper, nitrogen is used as fluid working medium to satisfy the demand on high temperature resistance. Concerning the blank material used, formability of Mg-containing aluminium alloys shows strong strain rate sensitivity at elevated temperatures. To figure out the optimal strain rates for this particular process, a control system for forming processes is developed within the scope of this paper. Additionally, FE-simulations are carried out and adapted to the experiment, based on the generated process data. FE-investigations include forming of domes (bulging) as well as shape-defined forming, having the objective to increase formability in critical form elements by applying optimal strain rates. Here, a closed-loop process control for gas-pressure forming at elevated temperatures is to be developed in the next stages of the project. (orig.)

  2. Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

    Science.gov (United States)

    Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-01-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  3. A study on the boss forming process of AZ31 Mg alloy sheet

    Science.gov (United States)

    Park, Ji Eon; Kim, Hyung Rae; Ahn, Sang Ho; Chang, Young Won

    2009-06-01

    A series of boss forming tests has been carried out using an AZ31 Mg alloy sheet at 250 °C, 300 °C, and 350 °C with various lubrication conditions to obtain optimum process conditions. The Mg alloy sheet had a homogeneous distribution of very fine sized grains. Surface defects generated during boss forming process could be reduced by changing the friction conditions, as prescribed by FEM analysis using the DEFORM 2D program. The modified boss forming process, lubricating only on the front side, was found to be successful in manufacturing the boss without defects.

  4. Thermodynamics and fragility of glass-forming alloys

    Energy Technology Data Exchange (ETDEWEB)

    Battezzati, L., E-mail: livio.battezzati@unito.it [Dipartimento di Chimica e Centro NIS, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy); Dalla Fontana, G. [Dipartimento di Chimica e Centro NIS, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy)

    2014-02-15

    Highlights: ► Thermodynamic and dynamic properties of metallic melts compared with those of other glass formers. ► Relationships between ΔS{sub g}/ΔC{sub p,g} and relevant temperatures for the glass demonstrated. ► Correspondence with either hyperbolic or Gaussian distribution of the states in the PEL shown. ► Correlations allow estimate of unknown quantities and pinpoint peculiar behavior of liquid. -- Abstract: The existing correlation between the extensive properties, ΔH and ΔS, the enthalpy and entropy difference between liquid and crystal phases has been checked to relate metallic glasses to other classes of amorphous materials. Expressing the specific heat difference, ΔC{sub p}, of molten and crystalline metallic glass-formers as a function of temperature with different functional trends, parametric expressions of fragility are derived using relevant temperatures for alloys. It is shown that relationships between the ΔS{sub g}/ΔC{sub p,g} ratio and such temperatures are useful to estimate unknown quantities when the experimental determination of the specific heat is possible. Thermodynamic indicators of fragility are compared to the kinetic fragility obtained from viscosity data accounting for the estimated errors on parameters which are derived from extrapolations. The outcome of the analysis indicates that a relationship between thermodynamic and kinetic parameters exists. Moreover a systematic scatter for some alloys indicates a diverse behavior which can be ascribed to structure modification either in the liquid or in the solid reference state.

  5. 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.

  6. Microstructure behavior and metal flow during continuously extending-extrusion forming of semisolid A2017 alloy

    Institute of Scientific and Technical Information of China (English)

    GUAN Ren-guo; WEN Jing-lin; WANG Shun-cheng; LIU Xiang-hua

    2006-01-01

    A self-designed test machine of continuously semisolid extending extrusion was made to produce the flat bar of A2017 alloy. The slurry of A2017 alloy with spherical or elliptical structures was obtained. During manufacturing semisolid A2017 alloy by the proposed process, the spherical grain was formed with the application of the large force provided by the rough roll. By controlling the casting temperature, the products of A2017 alloy with fine surfaces and rectangular transections of 14 mn×25 mm were produced. The microstructure of the product is fine with the stripped appearance. The fracture strength and elongation of the product are increased by 100 MPa and 29%, respectively.

  7. Forming of magnesium alloy microtubes in the fabrication of biodegradable stents

    Institute of Scientific and Technical Information of China (English)

    Lixiao Wang; Gang Fang; Lingyun Qian; Sander Leeflang; Jurek Duszczyk; Jie Zhou

    2014-01-01

    Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, because of the poor workability of magnesium at room temperature. In the present study, the forming processes, i.e., hot indirect extrusion and multi-pass cold drawing were used to fabricate seamless microtubes of a magnesium alloy. The magnesium alloy ZM21 was selected as a representative biomaterial for biodegradable stent applications. Microtubes with an outside diameter of 2.9 mm and a wall thickness of 0.2 mm were successfully produced at the fourth pass of cold drawing without inter-pass annealing. Dimensional evaluation showed that multi-pass cold drawing was effective in correcting dimensional non-uniformity arising from hot indirect extrusion. Examinations of the microstructures of microtubes revealed the generation of a large number of twins as a result of accumulated work hardening at the third and fourth passes of cold drawing, corresponding to the significantly raised forming forces. The work demonstrated the viability of the forming process route selected for the fabrication of biodegradable magnesium alloy microtubes.

  8. Hydroxyapatite precipitation on nanotubular films formed on Ti-6Al-4V alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Chae-Ik; Jeong, Yong-Hoon [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State, University, Columbus, OH (United States)

    2013-12-31

    In this study, hydroxyapatite precipitation on nanotubular film-formed Ti-6Al-4V alloy for biomedical applications has been investigated using a variety of techniques. To prepare the substrate samples for hydroxyapatite (HA) deposition, the starting Ti-6Al-4V alloy was polished and heat-treated for 12 h at 1050 °C in an Ar atmosphere, followed by water-quenching at 0 °C. Nanotube formation on the titanium alloy was performed using anodization with a DC power supply at 30 V for 1 h in 1 M H{sub 3}PO{sub 4} + 0.8 wt.% NaF at 25 °C. Subsequent HA precipitation treatment was carried out by cyclic voltammetry over a potential range of −1.5 V to 0 V using a scanning rate of 100 mV/s in 0.03 M Ca(NO{sub 3}){sub 2} ∙ 4 H{sub 2}O + 0.018 M NH{sub 4}H{sub 2}PO{sub 4} at 80° ± 1 °C. Four different numbers of cycles were employed: 10, 20, 30, and 50. Surface morphology and structure were examined by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The heat-treated Ti–6Al–4V alloy has a needle-like duplex microstructure containing the martensitic α′ phase and β phase. Plate-like precipitates were formed on bulk Ti–6Al–4V alloy, and the size of these precipitates increased with the number of deposition cycles. The HA precipitates on the nanotube surface showed a mixture of plate-like and flower-like particles with more deposition cycles. The deposited HA phase in the coated layer had an amorphous structure, with particle composition in good agreement with Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}. - Highlights: • Hydroxyapatite (HA) precipitation on nanotubular films formed on Ti–6Al–4V alloy was investigated using a variety of experimental methods. • HA precipitation treatment was carried out using a cyclic voltammetry method after nanotube formation on Ti–6Al–4V alloy. • Plate-like precipitates were formed on the bulk (not anodized) alloy, and the

  9. The Effect of Alumina Dispersant Powder on the Workability of Chromia Based Refractory for IGCC Application

    Science.gov (United States)

    Ming, Zhao Jing; Xun, Yang Zheng; Hong, Hwang Kyu; Hwan, Park Sang

    2011-10-01

    The quality of refractory applied on IGCC is a key factor that affects the cost of production. The workability and microstructure of chromia based castable are varied by introducing different type of alumina dispersant powder, such as active alumina powder. In this study, three types of active alumina powder are added to improve the workability. It's proved that the specific surface area and particle size distribution of fine powders in matrix part greatly affect the flow values and microstructures.

  10. Investigation on inductive heating of A356 alloy for thixo-forming

    Institute of Scientific and Technical Information of China (English)

    Kai-kun Wang; Jian-lin Sun; Yong-lin Kang; Qi Zhang; Lei Yang; Chun-mei Ma

    2009-01-01

    To meet the demands of continuous stream-line for component production in the thixo-forming industry, billet heating should be of high quality and in a controllable way. A 4-step inductive heating strategy for aluminum alloy A356 was performed. Thixotropic testing and microstructure analysis showed that a homogenous temperature distribution was achieved after tempera-ture-power-time optimization. Theoretical analysis was given concerning the thermal conductivity and heat capacity of A356 be-tween conventional and semisolid casting microstructures. The experimental results show that the optimized 4-step strategy could bethe best strategy for billet heating during the thixo-forming of aluminum alloy A356.

  11. 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.

  12. Evaluation of forming limit in viscous pressure forming of automotive aluminum alloy 6k21-T4 sheet

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A ductile fracture criterion is introduced into numerical simulation to predict viscous pressure forming limit of the automotive body aluminum alloy 6k21-T4. The material constant in the ductile fracture criterion is determined by the combination of the viscous pressure bulging (VPB) test with numerical simulation. VPB tests of the aluminum alloy sheet are carried out by using various elliptical dies with different ratios of major axis to minor axis(β), and the bugling processes are simulated by the aid of the finite element method software LS-DYNA3D. On the basis of the stress and strain calculated from numerical simulations, the forming limits of bulging specimens obtained are predicted by the ductile fracture criterion, and compared with experimental results.The fracture initiation site and the minimal thickness predicted by the ductile fracture criterion are in good agreement with the experimental results.

  13. Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

    Science.gov (United States)

    Spahn, Olga B.; Lear, Kevin L.

    1998-01-01

    A semiconductor structure. The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g. Al.sub.2 O.sub.3), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3-1.6 .mu.m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation.

  14. FE simulation and process analysis on forming of aluminum alloy multi-layer cylinder parts with flow control forming

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-yun; WU You-sheng; XIA Ju-chen; HU Guo-an

    2005-01-01

    The aluminum alloy parts used in airbag of car were studied with flow control forming(FCF) method,which was a good way to low forming force and better mechanical properties. The key technology of FCF was the design of control chamber to divide metal flow. So, the design method of FCF was analyzed and two type of control chamber were put forward. According to divisional principle, calculation model of forming force and approximate formula were given. Then forming process of aluminum alloy multi-layer cylinder parts was simulated. The effect of friction factor, die radius and punch velocity on metal flow and forming force was obtained. Finally, the experiment was preformed under the direction of theory and finite element(FE) simulation results. And the qualified parts were manufactured. The simulation data and experimental results show that the forming sequence of inner wall and outer wall, and then the force step, can be controlled by adjusting the process parameters. And the FCF technology proposed has very important application value in precision forging.

  15. Laser forming of structures of zinc oxide on a surface of products from copper alloys

    Science.gov (United States)

    Abramov, D. V.; Gorudko, T. N.; Koblov, A. N.; Nogtev, D. S.; Novikova, O. A.

    Laser formation of a protective zinc oxide layer on a surface of products from copper alloys is present. This layer is formed with using of carbon nanotubes. Destructions of the basic material are avoided or minimized at laser nanostructuring of product surfaces. Such laser processing can be made repeatedly. Offered covering have self-clearing and water-repellent properties.

  16. The fluidity and molding ability of glass-forming Zr-based alloy melt

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined,which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected. As a result,a Zr-based bulk metallic glass ring was prepared successfully.

  17. Ferromagnetic Fe-based Amorphous Alloy with High Glass-forming Ability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A ferromagnetic amorphous Fe73Al4Ge2Nb1P10C6B4 alloy with highglass-forming ability was synthesized by melt spinning. The supercooled liquid region before crystallization reaches about 65.7 K. The crystallized structure consists of α-Fe, Fe3B, FeB, Fe3P and Fe3C phases. The Febased amorphous alloy exhibits good magnetic properties with a high saturation magnetization and a low saturated magnetostriction. The crystallization leads to an obvious decrease in the soft magnetic properties.

  18. High strength microstructural forms developed in titanium alloys by rapid heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ivasishin, O.M. [Institute of Metal Physics, Kiev (Ukraine)

    2001-09-01

    It is shown that rapid heat treatment of alpha+beta and beta titanium alloys, which includes rapid heating of alloys with initial equiaxed microstructure into single-phase beta field is able to produce microstructural forms in which high strength can be well balanced with other mechanical properties. Main advantage of rapid heating approach comes from the possibility to extend the level of ''useful'' strength. Desirably high strength is provided by intragranular morphology and microchemistry while beta-grain refinement permits a reliability of such high strength conditions. (orig.)

  19. A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Pan Wang

    2015-03-01

    Full Text Available A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy in large deformation bullet shell. In the first step, fine-grained microstructure preforms that are suitable for superplastic forming were obtained by reasonably designing the size of the initial blanks with the specific height-to-diameter ratio, upsetting the blanks and subsequent annealing. In the second step, the heat treated preforms were forged into the end products at the superplastic conditions. The end products exhibit high quality surface and satisfied microstructure. Consequently, this forming technology that not only avoids complicating the material preparation but also utilizes higher strain rate superplastic provides a near net-shaped novel method on magnesium forging forming technology using as-cast billet.

  20. Isothermal grain growth of reactive spray formed 7075 alloys in semi-solid state

    Institute of Scientific and Technical Information of China (English)

    Huimin Liu; Hua Cui; Bin Yang; Jishan Zhang

    2004-01-01

    The grain growth behavior in reactive spray formed 7075+2.91vol%TiC Al alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. The effects of in-situ TiC particles on the microstructure of spray formed 7075 Al alloy were also investigated. The specimens were heat-treated isothermally at various temperatures between the solidus and liquidus of 7075 Al alloy for times in the range of 10-60 min, then quenched in water. The microstructure of reheated specimens was characterized using scanning electron microscopy and optical microscopy. The grain size was measured using a mean linear intercept method.Results show that the in-situ TiC particles can effectively retard grain growth and refine the grain at a limited size. The grain growth exponent in Arrhenius equation increases from 2 to 3, which indicates that the in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solid state.

  1. Soft-ferromagnetic bulk glassy alloys with large magnetostriction and high glass-forming ability

    Directory of Open Access Journals (Sweden)

    Jiawei Li

    2011-12-01

    Full Text Available The effect of Dy addition on the glass-forming ability (GFA, magnetostriction as well as soft-magnetic properties and fracture strength in FeDyBSiNb glassy alloys was investigated. In addition to the increase of supercooled liquid region from 55 to 100 K, the addition of Dy is effective in approaching alloy to an eutectic point and increasing the saturation magnetostrction (λs. Accordingly, bulk glassy alloy (BGA rods with diameters up to 4 mm were produced, which exhibit a large λs as high as 65×10-6. Besides, the BGA system exhibits superhigh fracture strength of 4000 MPa, combined with good soft-magnetic properties.

  2. Unified constitutive modelling for two-phase lamellar titanium alloys at hot forming conditions

    Directory of Open Access Journals (Sweden)

    Yang Lei

    2016-01-01

    Full Text Available In this paper, a set of mechanism based unified viscoplastic constitutive equations have been established for two-phase titanium alloys with initial lamellar microstructure, which models the softening mechanisms of the alloys in hot forming conditions. The dislocation density, rotation and globularization of lamellar α-phase and their effects on flow behaviour can also be modelled. The values of material constants in the equation set have been calibrated, according to stress-strain curves and globularization fractions of lamellar α-phase obtained from compression tests at a range of temperatures and strain rates, using a genetic algorithm (GA based optimisation method. Based on the determined constitutive equations, flow stress and globularization evolution of Ti-17 and TA15 alloys at different temperatures and strain rates were predicted. Good agreements between the experimental and computed results were obtained.

  3. Analysis of melting and solidification behaviour of glass-forming alloys by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Baser, T.A.; Baricco, M. [Dipartimento di Chimica, Universita di Torino (Italy); NIS, Torino (Italy); Bostrom, M. [The European Synchrotron Radiation Facility, (ESRF), Grenoble (France); Stoica, M. [Leibniz-Institut fuer Festkorper- und Werkstoffforschung Dresden (Germany); Yavari, A.R. [Laboratorie de Thermodynamique et Physico-chimie Metallurgique (LTPCM-UMR 5614), Institut National Polytechnique de Grenoble, CNRS (France)

    2007-06-15

    This paper aims to study the melting and solidification behaviour of Fe48Cr15Mo14Y2C15B6 and Cu50Zr50 glass-forming alloys by in-situ synchrotron X-ray diffraction from data obtained at the European Synchrotron Radiation Facility (ESRF). Melting and solidification behaviour for both alloys were measured by high temperature differential scanning calorimetry (HTDSC). The phase identification was performed by Rietveld refinement of diffraction patterns collected as a function of temperature. The phase mixture on melting and solidification has been clarified, confirming that in-situ X-ray diffraction by synchrotron radiation is a powerful technique for the study of phase transformations in alloys. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  4. Microstructure characteristics of laser forming repaired Ti60 alloy

    Institute of Scientific and Technical Information of China (English)

    Yanhong Liu; Jing Chen; Qiang Zhang; Lei Xue; Xin Lin; Weidong Huang

    2011-01-01

    The microstructure characteristics of laser forming repaired(LFR) Ti60(Ti-5.6A1-4.8Sn-2Zr-1Mo-O.35Si0.3Nb) as-deposited and annealed samples are analyzed.The microstructure of as-deposited repaired zone (RZ) consists of epitaxial columnar prior β grains,in which fine woven a laths and β-phase between a laths exist.The heat-affected zone(HAZ) experiences a continuous microstructural transition from duplex microstructure of the base metal zone(BMZ) to the microstructure of RZ.The presence of silicide precipitates is observed in both RZ and BMZ in an annealed sample by transmission electron microscopy.They are identified as(Ti,Zr)6Si3 distributed mainly at the α/β interface with the size of 100-300 nm.The fine a2 precipitates are detected in BMZ by electron diffraction; there was no a2 detected in RZ.

  5. FEM Analysis of Spring-backs in Age Forming of Aluminum Alloy Plates

    Institute of Scientific and Technical Information of China (English)

    Huang Lin; Wan Min; Chi Cailou; Ji Xiusheng

    2007-01-01

    The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and formingtime on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method (FEM) analysis.

  6. 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.

  7. Calculation of Reactive-evaporation Rates of Chromia

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, G.R.

    2008-04-01

    A methodology is developed to calculate Cr-evaporation rates from Cr2O3 with a flat planar geometry. Variables include temperature, total pressure, gas velocity, and gas composition. The methodology was applied to solid-oxide, fuel cell conditions for metallic interconnects and to advanced-steam turbines conditions. The high velocities and pressures of the advanced steam turbine led to evaporation predictions as high as 5.18 9 10-8 kg/m2/s of CrO2(OH)2(g) at 760 °C and 34.5 MPa. This is equivalent to 0.080 mm per year of solid Cr loss. Chromium evaporation is expected to be an important oxidation mechanism with the types of nickel-base alloys proposed for use above 650 °C in advanced-steam boilers and turbines. It is shown that laboratory experiments, with much lower steam velocities and usually much lower total pressure than found in advanced steam turbines, would best reproduce chromium-evaporation behavior with atmospheres that approach either O2 + H2O or air + H2O with 57% H2O.

  8. Nanostructure and corrosion behaviors of nanotube formed Ti-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    Won-Gi KIM; Han-Cheol CHOE

    2009-01-01

    In order to investigate the nanostructures and corrosion behaviors of Ti-Zr alloys, nanotube formed Ti-Zr(10%, 20%, 30% and 40% in mass fraction) alloys were prepared by arc melting and the condition of controlling nanostructure was at 1 000 ℃ for 24 h in argon atmosphere; formation of nanotubes was conducted by anodizing a Ti-Zr alloy in H3PO4 electrolyte with a small amount of fluoride ions at room temperature. The corrosion properties of specimens were examined through potentiodynamic test (potential range of -1 500-2 000 mV) in 0.9% NaCl solution by using potentiostat. Microstructures of the alloys were observed by optical microscope(OM), field emission scanning electron microscope(FE-SEM) and X-ray diffractometer(XRD). Diameter of nanotube does not depend on Zr content, but interspace of nanotube predominantly depends on Zr content, which confirms that ZrO2 oxides play a role to increase the interspace of nanotube formed on the surface.

  9. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2004-08-31

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (i) prescribe extrusion consolidation methodologies via detailed

  10. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2004-03-31

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (1) prescribe extrusion consolidation methodologies via detailed

  11. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2004-05-31

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (1) prescribe extrusion consolidation methodologies via detailed

  12. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2004-11-30

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (i) prescribe extrusion consolidation methodologies via detailed

  13. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2005-02-28

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (i) prescribe extrusion consolidation methodologies via detailed

  14. Bioactive titanate layers formed on titanium and its alloys by simple chemical and heat treatments.

    Science.gov (United States)

    Kokubo, Tadashi; Yamaguchi, Seiji

    2015-01-01

    To reveal general principles for obtaining bone-bonding bioactive metallic titanium, Ti metal was heat-treated after exposure to a solution with different pH. The material formed an apatite layer at its surface in simulated body fluid when heat-treated after exposure to a strong acid or alkali solution, because it formed a positively charged titanium oxide and negatively charged sodium titanate film on its surface, respectively. Such treated these Ti metals tightly bonded to living bone. Porous Ti metal heat-treated after exposure to an acidic solution exhibited not only osteoconductive, but also osteoinductive behavior. Porous Ti metal exposed to an alkaline solution also exhibits osteoconductivity as well as osteoinductivity, if it was subsequently subjected to acid and heat treatments. These acid and heat treatments were not effective for most Ti-based alloys. However, even those alloys exhibited apatite formation when they were subjected to acid and heat treatment after a NaOH treatment, since the alloying elements were removed from the surface by the latter. The NaOH and heat treatments were also not effective for Ti-Zr-Nb-Ta alloys. These alloys displayed apatite formation when subjected to CaCl2 treatment after NaOH treatment, forming Ca-deficient calcium titanate at their surfaces after subsequent heat and hot water treatments. The bioactive Ti metal subjected to NaOH and heat treatments has been clinically used as an artificial hip joint material in Japan since 2007. A porous Ti metal subjected to NaOH, HCl and heat treatments has successfully undergone clinical trials as a spinal fusion device.

  15. Effects of alloy heat treatment on oxidation kinetics and scale morphology for Crofer 22 APU

    Science.gov (United States)

    Magdefrau, Neal J.; Chen, Lei; Sun, Ellen Y.; Aindow, Mark

    2013-11-01

    The effect of alloy heat treatment on the oxidation kinetics and oxide scale microstructure of Crofer 22 APU has been studied. Parabolic oxidation rate constants were measured for the as-received alloy and after pre-oxidation heat treatment in argon at 1050 °C for 1 and 4 h. The oxide scale microstructure was investigated using scanning electron microscopy, focused ion beam milling and transmission electron microscopy. It was found that the alloy forms a two-layer scale with a continuous chromia layer and a discontinuous MnCr2O4 overlayer. Two forms of internal oxides were also formed: subscale pockets of spinel and isolated TiOx precipitates in the underlying alloy. The pre-oxidation heat treatment had a profound effect on the grain size and morphology of the Cr2O3 and MnCr2O4 layers in the scale. The heat-treated samples exhibit a 3.5× lower parabolic oxidation rate constant than the as-received Crofer 22 APU. This improvement in oxidation resistance is attributed to the dramatic differences in the morphology of the oxide scale that forms during the earliest stages of oxidation (<5 h). The implications of these findings for oxidation mechanisms and long-term SOFC performance are discussed.

  16. Influence of forming velocity on the uniformity of microstructure of semisolid die forging 7075 alloy

    Directory of Open Access Journals (Sweden)

    Jianbo TAN

    2016-12-01

    Full Text Available Liquid phase segregation frequently occurs in the process of semi solid die forging, which makes the parts appear "weak point" or "weak region", and usually, the "weak point" or "weak area" is the reason of crack and service condition failure. In order to analyze the influence factors of the liquid phase segregation of the semi solid die forging, DEFORM-3D is used for the numerical simulation of semi-solid die forging forming process of 7075 aluminum alloy, to study the influence rule of forming velocity on the forming process of cup part. Based on the simulation results, the rheological die forging forming of 7075 aluminum alloythe part is conducted to research the influence of forming velocity on the uniformity of microstructure by means of press machine and cup mould. The simulation and experimental results show that as the filling velocity is faster, the forming process is more unstable; under the condition of head temperature of 400 ℃, the forming pressure of 50 MPa, and the alloy temperature 628 ℃, as the forming velocity increases, the liquid phase segregation degree of cup part increases, and the microstructure is far from uniformity. The segregation degree is up to 18.2% as the forming velocity is 5 mm/s.

  17. Effect of scandium addition on the microstructure, mechanical and wear properties of the spray formed hypereutectic aluminum–silicon alloys

    Energy Technology Data Exchange (ETDEWEB)

    Raghukiran, Nadimpalli; Kumar, Ravi, E-mail: nvrk@iitm.ac.in

    2015-08-12

    Hypereutectic Al–x%Si–0.8Sc alloys (x=13, 16, 19 and 22 wt%) were produced by spray forming. The microstructures of all the alloys exhibited very fine silicon phase with average size of about 5–10 µm irrespective of the silicon content of the alloy. Transmission electron microscopy revealed the presence of a nano-scale scandium rich phase, identified as AlSi{sub 2}Sc{sub 2} (V-phase) uniformly distributed in the alloy. The presence of V-phase resulted in higher matrix hardness (1.34 GPa) in contrast to 1.04 GPa observed in the case of binary Al–Si alloys by nanoindentation. Isothermal heat treatment at 375 °C revealed insignificant coarsening of silicon phase in both binary and ternary alloys. The Al–x%Si–0.8Sc alloys exhibited higher flow stress and tensile strength in contrast to their binary alloy counterparts which was attributed to the bi-modal size distribution of the strengthening phases in the form of nano-scale V-phase and sub-micron to 10 µm size silicon particles. The pin-on-disk wear tests exhibited appreciable improvement in the wear performance of the relatively low-silicon content ternary alloys over their binary counterparts while the high-silicon content binary and ternary alloys exhibited no much difference in the wear performance.

  18. Forming of a super plastic sheet metal made of MgAZ31 alloy

    Science.gov (United States)

    Zaid, Adnan I. O.; Al-Matari, Mustafa A. A.; Nazzal, M. A. H.

    2016-08-01

    Metal forming industries are constantly looking for advanced innovation, economical and energy efficient techniques. Superplastic forming has a great potential to be one of those advanced forming methods. It is a near net shape forming process which uses a unique type of materials where elongation exceeds 200% during a controlled forming conditions, e.g. temperature, pressure, and strain rate. Most of superplastic materials are formed by gas technique at elevated temperature. The main objectives of the research work in this paper were: to study the effects of the forming schemes on the forming time and thickness distribution of the formed and device a method to improve the forming part thickness and its uniformity distribution and the forming time. In this paper, a hydraulic and heating system were designed and manufactured to facilitate the experimental investigation. The superplastic magnesium alloy AZ31, Mg AZ31, was formed at 350°C with different strain rates to investigate the effect of the forming pressure profiles on the thickness uniformity of the superplastic formed part. The pressure profiles were generated based on Dutta and Mukherjee analytical approach. Finally, a variable strain rate method is modified to improve the uniformity of the thickness distribution of the formed part and reduce the forming time; which is a major limitation of superplastic forming.

  19. Investigation of Intermetallic Compound Formed from Rapid Solidification of Al-Ti-RE Alloy

    Institute of Scientific and Technical Information of China (English)

    杨明珊; 王振飞

    2004-01-01

    Al-Ti alloy containing rare earth elements can produce fine,uniform dispersion intermetallic phase through rapid solidification(RS)technology.RS Al-Ti-RE alloy can be designed for applications at elevated-temperature since the intermetallic compound has good thermal stability.A transmission electron microscopy investigation shows the intermetallic phase has a diamond cubic structure(a=1.47736 nm),with space group Fd3m.The chemical stoichiometry is Al20Ti2La.The particle is formed from the melting directly,prior to other phases,and the nucleus is formed from icosahedrons composed with twenty tetrahedrons.Twin crystal structure plays an important role in the nucleation stage.

  20. 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.

  1. Wear resistance of TiN(Ti2N)/Ti composite layer formed on C17200 alloy by plasma surface Ti-alloying and nitriding

    Science.gov (United States)

    Liu, L.; Shen, H. H.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

    2016-12-01

    The duplex treatment of plasma Ti-alloying and plasma nitriding was applied on the surface of C17200 alloy to improve its wear resistance. C17200 substrate was alloyed with Ti using double glow plasma alloying to form a Ti-alloyed layer in its surface, and then treated by plasma nitriding to make a TiN(Ti2N) alloying layer based on the Ti-alloyed surface. The microstructure and formation mechanism were studied by using GDOES, XRD and SEM. The hardness, tribological property and electrical conductivity of C17200 alloy after plasma alloying and nitriding were investigated by mean of micro-hardness tester, friction and wear testers as well as impedance analyzers. Modulus of elasticity and the adhesive strength of TiN(Ti2N)/Ti composite layer were evaluated by nano-indenter and scratch tester. The result shows that a TiN(Ti2N)-Ti-Be-Cu composite layer with a thickness of 27 μm is formed in the C17200 surface and is mainly composed of TiN, Ti2N, Cu(Ti) solid solution, etc. The composite alloying surface consists of the hard TiN(Ti2N)-rich layer on the top surface and Ti-Cu-Be diffusion layer, showing a strong adhesive strength with the C17200 substrate and a little decrease in the modulus of elasticity. A certain amount of Cu and Be together with TiN/Ti2N exists in the outmost, resulting in a better combination of wear resistance and conductive performance.

  2. Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy

    Institute of Scientific and Technical Information of China (English)

    Wenbo HAN; Kaifeng ZHANG; Guofeng WANG; Xiaojun ZHANG

    2005-01-01

    Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6Al-4V sheet material. The sandwich structure of Ti-6Al-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.

  3. New Zr-based glass-forming alloys containing Gd and Sm

    Directory of Open Access Journals (Sweden)

    Luis César Rodríguez Aliaga

    2012-10-01

    Full Text Available The effect of minor additions of Gd and Sm on the glass-forming ability (GFA of Cu-Zr-Al alloys is investigated here. The rationale for these additions is the fact that the atomic size distribution can increase GFA by changing the topology of the alloy as a function of cluster stability, which is tied to the electronegativity and ionic and covalent nature of alloys. Ingots with nominal compositions of Cu40Zr49Al10.5Gd0.5, Cu40Zr49Al10.5Sm0.5 and Cu39Zr50Al9Gd2 were prepared by arc-melting and rapidly quenched ribbons were produced by the melt-spinning technique. Bulk samples with a thickness of up to 10 mm were also produced by casting, using a wedge-shaped copper mold. The samples were characterized by differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy. The three compositions showed a fully amorphous structure in the ribbons and a predominantly homogeneous amorphous structure with a thickness of up to 10 mm, although some gadolinium oxide crystals as well as samarium compounds were found to be scattered in the amorphous matrix in 5-mm-thick samples. The amorphous phases in the alloys showed high thermal stability with a supercooled liquid region (ΔTx of about 70 K.

  4. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Bimal Kad

    2007-09-30

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program were to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined was iterative and intended to systematically (i) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, to be (ii) evaluated at 'in-service' loads at service temperatures and environments. Our report outlines the significant hoop creep enhancements possible via secondary cross-rolling and/or flow-forming operations. Each

  5. Enhancement of Formability of AA5052 Alloy Sheets by Electrohydraulic Forming Process

    Science.gov (United States)

    Ahmed, Meraj; Kumar, D. Ravi; Nabi, M.

    2017-01-01

    Formability of lightweight materials like Al and Mg alloys is a major concern for their application in automobiles. Forming limit diagram (FLD) and strain distribution are extremely useful in the assessment of overall formability of sheet metals. At very high strain rates, the deformation behavior of Al alloys and the safe forming window could be different from quasi-static conventional forming. In this paper, formability of Al 5052 alloy sheets of 0.5 mm thickness has been assessed in electrohydraulic forming (EHF) in terms of FLD and strain distribution and compared with formability in conventional forming by punch-stretching experiments. EHF is a high strain rate forming process which utilizes energy released from a capacitor bank to generate shockwaves in a fluid medium. Experiments have been conducted at different energy levels to identify the highest safe strains in different modes of deformation. From the experimental results, it has been observed that the limit strains increased by nearly 45-50% in all the three regions of the FLD (tension-tension, plane strain and tension compression). Unlike in the case of conventional forming, no clear necking due to strain localization has been observed prior to failure due to very high strain rates of the order of 103/s. The strain distribution has been found to be more uniform in the case of EHF with a single strain peak at the pole. Absence of friction in EHF also leads to higher degree of biaxiality leading to higher limit strains in biaxial tension. In the case of EHF, the effective strain and hardness are maximum at the pole and their variation correlated well with the findings from the strain distribution analysis. In all modes of deformation, the features of fractured surface in EHF appeared different from a normal ductile failure.

  6. Numerical simulation and its application of rheological forming of titanium alloy vane disk

    Institute of Scientific and Technical Information of China (English)

    YU Min; LUO Ying-she; PENG Xiang-hua; QIN Yin-hui

    2006-01-01

    The hot rheological forming method was proposed to form the second titanium alloy vane disk. The hot rheological forming process of the TC11 titanium vane disk under a certain temperature and different strain rates was investigated by using the bulk forming software of DEFORM 3D. A series of results including temperature field,equivalent strain distribution,load-stroke curve and rheology procedure were obtained by this finite element method. The rheological forming characteristics were well realized and the forming parameters were determined. The results and analysis show that with decreasing strain rate,the metal flow more equably and the filling of the vane shape is also better. Moreover,the mechanical properties and microstructures of the products produced by this new technique are improved evidently compared with that produced by traditional method.

  7. Semi-solid forming of Al and Mg alloys for transportation applications

    Energy Technology Data Exchange (ETDEWEB)

    Shehata, M. [Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada). Materials Technology Lab

    2001-07-01

    This Power Point presentation outlined the process of semi-solid forming of aluminium and magnesium alloys for transportation applications with particular reference to its advantages and applications. The presentation also referred to the Canadian Lightweight Materials Research Initiative (CLiMRI) Project which is aimed at optimizing semi-solid processing of aluminium and magnesium alloys in the following four areas: (1) production of thixotropic feed stock suitable for semi-solid forming, (2) optimizing heating of feed stock using an energy efficient high frequency induction heating, (3) optimizing semi-solid die casting, forging and extrusion, and (4) modeling. Materials characterisation was also part of the project. Semi-solid forming methods include thixocasting, thixoforging, thixomolding and rheocasting or slurry on demand. The general advantages of semi-solid forming methods over conventional forming methods for the die casting and forging processes were described. In the die-casting process, semi-solid forming methods require a low cast temperature of 580 degrees C. They require less heat removal, less cycle time, and produce only a small amount of shrinkage. They also result in enhanced mechanical properties. Typical automotive applications are for engine mounts, hydraulic cylinders, air-conditioner scrolls, wheels and other structural parts such as bearings and knuckles. 14 figs.

  8. Experimental and FE simulation validation of sheet thickness optimization in superplastic forming of Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kumaresan, G.; Jothilingam, A. [Anna University, Chennai (India)

    2016-07-15

    Superplasticity is the ability of a polycrystalline materials to exhibit very large elongations without necking prior to failure. In this paper, the superplastic forming potential of fine grained 7075 aluminium alloy was studied. The process parameters like pressure, forming time and initial sheet thickness were selected, using the design of experiments technique. The same condition of formation process was attempted in the finite element simulation using ABAQUS software. The deviation of the thickness distribution between the simulation and experiment was made and the variation lies within 8%.

  9. Adherent Al2O3 scales formed on undoped NiCrAl alloys

    Science.gov (United States)

    Smialek, James L.

    1987-01-01

    Changes in the spalling behavior of Al2O3 scales formed on an undoped NiCrAl alloy are described. Two samples of Ni-15Cr-13Al (wt pct), one a control and the other sanded, were subjected to 25 oxidation cycles. It is observed that adherent scales formed on the sanded sample; however, the control sample had speckled, spalled scales. The data reveal that the adherent scales are caused by repeated removal of surface layers after each oxidation cycle. It is determined that interfacial segregation of sulfur influences spallation and sulfur removal increases bonding. The effect of moisture on scale adhesions is investigated.

  10. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2006-09-30

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined here is iterative in nature and is intended to systematically (a) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, which will be (b) evaluated at ''in-service'' loads at service temperatures and environments. In this 12th quarter of performance, program activities are concluded for Task 2 and continuing

  11. Corner forming of AZ61A magnesium alloy tube within warm hydroforming

    Institute of Scientific and Technical Information of China (English)

    HU Lan; HAN Cong; HE Zhu-bin; TANG Ze-jun; LIU Gang; YUAN Shi-jian

    2009-01-01

    The corners with small radii on cross sections are crucial for forming hydroformed components with polygonal sections. In this paper, warm hydroforming experiments of AZ61 A magnesium alloy tubes were carried out to study the forming regularity of round corners by using a demonstration part with square sections.Effects of temperature on radius forming, thinning ratio distribution and microstructure were revealed and a component with relative outer corner radius of 3.0 was obtained by warm hydroforming at 240℃. The minimum thickness of the formed square section was located in the transition position between the corner and the straight wall. The thinning ratio of the round corner increased with the increase of forming temperature. Formability of the magnesium tube was improved by raising temperature under the effect of dynamic recrystallization at 240℃.

  12. Biodegradation behavior of micro-arc oxidized AZ31 magnesium alloys formed in two different electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Seyfoori, A. [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mirdamadi, Sh., E-mail: Mirdamadi@iust.ac.ir [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Khavandi, A.; Raufi, Z. Seyed [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphate coating has lesser degradation rate than silicate coating in r-SBF solution. Black-Right-Pointing-Pointer Farringtonite phase is chemically more stable than forsterite phase in SBF solution. Black-Right-Pointing-Pointer Apatite forming ability of forsterite containing coating is better than farringtonite containing film. Black-Right-Pointing-Pointer The hydrophilisity nature of silicate film on magnesium alloy with respect to its roughness, is greater than phosphate film. - Abstract: Degradation behavior of coated magnesium alloys is among most prominent factors for their biomedical applications. In this study, bio-corrosion behavior of micro-arc oxidized magnesium AZ31 alloys formed in silicate and phosphate baths was investigated in r-SBF medium. For this purpose polarization behavior and open circuit profile of the coated samples were achieved by electrochemical and immersion tests, respectively. Moreover, the morphology and composition of the coatings were evaluated before and after immersion test using scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The results showed that the phosphate film had better corrosion resistance and greater thickness than silicate film and, in turn, the lesser degradability in SBF solution, so that Ca{sup 2+} and PO{sub 4}{sup 3-} containing compounds were more abundant on silicate film than phosphate film. Moreover phosphate film had greater surface roughness and lesser hydrophilic nature.

  13. Microstructure and high temperature mechanical properties of laser rapidly formed Ti-6Al-4V alloy

    Institute of Scientific and Technical Information of China (English)

    XUE Lei; CHEN Jing; LIN Xin; LU Xiao-wei; WANG Wei; HUANG Wei-dong

    2006-01-01

    Several tensile samples were prepared using laser rapid forming (LRF) with Ti-6Al-4V alloy as powder material, and the samples were annealed. The microstructure and high temperature mechanical properties of laser formed Ti-6Al-4V alloy through annealing treatment were investigated. The short-term and long-term tensile tests at 350 ℃ were performed. The results show that the microstructure of LRF samples consists of the large columnar prior β grains which grow epitaxially from the substrate along the deposition direction. There are Widmanst-tten α laths in prior β grains, but α laths in annealed microstructure are coarser, and their aspect ratio is lower than that in as-deposited microstructure. In addition, the prior β grain boundary is also coarsened and broken off through the annealing treatment. The high temperature mechanical properties of the annealed LRF samples exceed those of casting alloy significantly, especially the stress-rupture lifetime reaches 661.7 h even while the test stress increases from initial value of 490 MPa to the final stress of 800 MPa gradually.

  14. Interatomic potential for the compound-forming Li–Pb liquid alloy

    Energy Technology Data Exchange (ETDEWEB)

    Fraile, Alberto, E-mail: albertofrailegarcia@gmail.com [Instituto de Fusión Nuclear, ETSI Industriales, Universidad Politécnica de Madrid, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Cuesta-López, Santiago, E-mail: scuesta@ubu.es [Universidad de Burgos, Parque Científico I+D+I, Plaza Misael Bañuelos s/n, 09002 Burgos (Spain); Caro, Alfredo; Schwen, Daniel [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Manuel Perlado, J. [Instituto de Fusión Nuclear, ETSI Industriales, Universidad Politécnica de Madrid, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

    2014-05-01

    Atomistic simulations of liquid alloys face the challenge of correctly modeling basic thermodynamic properties. In this work we present an interatomic potential for this system, as well as a study of physical properties of Li–Pb alloys. Despite the complexity due to Li–Pb being a compound forming system where charge transfer is expected, we show here how the empirical EAM formalism is able to satisfactorily describe several physical properties in a wide range of Li concentration. Application of our potential to Li–Pb eutectic allows us to correctly predict many physical properties observed experimentally and calculated with ab initio techniques, providing in this way a potential suitable for future studies in the context of tritium breeder blanket designs in Fusion technology.

  15. 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.

  16. Study of a New Chromium-Free Conversion Coating Formed on ZnAl Alloy

    Institute of Scientific and Technical Information of China (English)

    LONG Jin-ming; GUO Zhong-cheng; HAN Xia-yun; YANG Ning

    2004-01-01

    A new chromium-free conversion film was obtained on surface of a ZnAl alloy by chemical conversion process.Influence of the additives in treating solution containing cerium salt on the corrosion protection of the conversion film formed on zinc alloy was investigated. Corrosion tests and electrochemical measurements in sodium chloride solution were performed. The microstructure and composition of the coatings were examined by means of SEM, EDS and XRD. It was found that the corrosion protection capabilities of the conversion film are markedly increased with the cerium nitride plus additives (hydrogen fluoride acid and an organic inhibitor) treating process. The modified conversion film is an organic/inorganic composite coating and is much more corrosion resistant than the conventional chromate conversion coating and the single cerium conversion coating.

  17. Study of a New Chromium-Free Conversion Coating Formed on ZnAl Alloy

    Institute of Scientific and Technical Information of China (English)

    LONGJin-ming; GUOZhong-cheng; HANXia-yun; YANGNing

    2004-01-01

    A new chromium-free conversion film was obtained on surface of a ZnA1 alloy by chemical conversion process. Influence of the additives in treating solution containing cerium salt on the corrosion protection of the conversion film formed on zinc alloy was investigated. Corrosion tests and electrochemical measurements in sodium chloride solution were performed. The microstructure and composition of the coatings were examined by means of SEM, EDS and XRD. It was found that the corrosion protection capabilities of the conversion film are markedly increased with the cerium nitride plus additives (hydrogen fluoride acid and an organic inhibitor) treating process. The modified conversion film is an organic/inorganic composite coating and is much more corrosion resistant than the conventional chromate conversion coating and the single cerium conversion coating.

  18. Corrosion of pre-oxidized nickel alloy X-750 in simulated BWR environment

    Science.gov (United States)

    Tuzi, Silvia; Lai, Haiping; Göransson, Kenneth; Thuvander, Mattias; Stiller, Krystyna

    2017-04-01

    Samples of pre-oxidized Alloy X-750 were exposed to a simulated boiling water reactor environment in an autoclave at a temperature of 286 °C and a pressure of 80 bar for four weeks. The effect of alloy iron content on corrosion was investigated by comparing samples with 5 and 8 wt% Fe, respectively. In addition, the effect of two different surface pre-treatments was investigated. The microstructure of the formed oxide scales was studied using mainly electron microscopy. The results showed positive effects of an increased Fe content and of removing the deformed surface layer by pickling. After four weeks of exposure the oxide scale consists of oxides formed in three different ways. The oxide formed during pre-oxidization at 700 °C, mainly consisting of chromia, is partly still present. There is also an outer oxide consisting of NiFe2O4 crystals, reaching a maximum size of 3 μm, which has formed by precipitation of dissolved metal ions. Finally, there is an inner nanocrystalline and porous oxide, with a metallic content reflecting the alloy composition, which has formed by corrosion.

  19. Superplastic forming of Al-Li alloys for lightweight, low-cost structures

    Science.gov (United States)

    Hales, Stephen J.; Wagner, John A.

    1991-01-01

    Superplastic forming of advanced aluminum alloys is being evaluated as an approach for fabricating low-cost, light-weight, cryogenic propellant tanks. Built-up structure concepts (with inherent reduced scrap rate) are under investigation to offset the additional raw material expenses incurred by using aluminum lithium alloys. This approach to fabrication offers the potential for significant improvements in both structural efficiency and overall manufacturing costs. Superplasticity is the ability of specially processed material to sustain very large forming strains without failure at elevated temperatures under controlled deformation conditions. It was demonstrated that superplastic forming technology can be used to fabricate complex structural components in a single operation and increase structural efficiency by as much as 60 percent compared to conventional configurations in skin-stiffened structures. Details involved in the application of this technology to commercial grade superplastic aluminum lithium material are presented. Included are identification of optimum forming parameters, development of forming procedures, and assessment of final part quality in terms of cavitation volume and thickness variation.

  20. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2005-06-27

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (i) prescribe extrusion consolidation methodologies via detailed

  1. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2005-11-23

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in crossrolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (1) examine and identify post-extrusion forming methodologies to

  2. Effect of blank holder pressure on viscous pressure forming aluminum alloy ladder parts

    Institute of Scientific and Technical Information of China (English)

    王忠金; 王新云; 王仲仁

    2002-01-01

    Viscous pressure forming (VPF), is suitable for forming difficult-to-form sheet metal parts. An investigation in the effect of blank holder pressure (BHP) on VPF aluminum alloy ladder parts was conducted. Based on experimental and numerical simulation results of the effect of BHP on dimensional accuracy, wall-thickness reduction, forming pressure, material flow and defects (such as wrinkling and fracture) of specimens, the effect patterns of BHP load path on VPF ladder parts were explained. The limits of BHP corresponding to specimens with no defect and with wrinkling or fracture defect were determined. In the limits of formable BHP, the variable load path of BHP was beneficial to drawing blank into the die and decreasing wall-thickness reduction of specimens. The experimental results show that the ladder parts of good surface fineness and high dimensional accuracy can be obtained by variable load paths of BHP.

  3. Equilibrium electrochemical synthesis diagrams of systems, forming homogeneous alloys and compounds

    Directory of Open Access Journals (Sweden)

    Kaptay G.

    2003-01-01

    Full Text Available In the present paper thermodynamic limitations will be derived and summarized in the form of Equilibrium Electrochemical Synthesis (EES diagrams, in order to predict the composition of the equilibrium phase, synthesized by galvanostatic co-deposition of components on inert electrodes. As a thermodynamic parameter, a difference of deposition potentials of pure components ( ∆E on inert cathodes is used (this parameter is a function of melt composition and temperature. Generally, the EES diagram predicts the equilibrium composition of the alloy as function temperature and ∆E. However, for systems with homogeneous alloy formation the composition- ∆E diagrams, drawn at a fixed temperature are more informative. As examples EES diagrams are constructed for the liquid Mg-Nd alloy, for some A(III-B(V (where A = Al, Ga, In and B = As, Sb, Si-C and for the Al-Ti system. For the Al-rich part of the Al-Ti system, also a semi-schematic non-equilibrium ES diagram is constructed. Based on these diagrams, the synthesis conditions of various phases has been discussed.

  4. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    Science.gov (United States)

    Smialek, J.; Gibala, R.

    1979-01-01

    The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids have been observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. It was postulated that the voids resulted from an excess number of oxygen vacancies near the oxide-metal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidations of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al,Cr)2O3 and Ni(Al,Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationships between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

  5. The glass-forming ability of model metal-metalloid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-03-14

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σ{sub S}/σ{sub L} and number fraction x{sub S} of the metalloid species. We show that the regime in the space of σ{sub S}/σ{sub L} and x{sub S} where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  6. The glass-forming ability of model metal-metalloid alloys

    Science.gov (United States)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

    2015-03-01

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σS/σL and number fraction xS of the metalloid species. We show that the regime in the space of σS/σL and xS where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  7. Ceramic coatings of LA141 alloy formed by plasma electrolytic oxidation for corrosion protection.

    Science.gov (United States)

    Li, Zhijun; Yuan, Yi; Sun, Pengpeng; Jing, Xiaoyan

    2011-09-01

    Superlight Mg-Li alloy is a promising structural materials in aerospace, automobile, and electronics because of its excellent properties such as low density, high ductility, superior strength-to-weight ratio, and good damping ability. The fabrication of compact plasma electrolytic oxidation coatings with excellent corrosion resistance is valuable for the widespread application of Mg-Li alloy. Here we present a ceramic coating on the surface of Mg-14Li-1Al (LA141) alloy for corrosion protection via plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte with tungstate as an additive. X-ray photoelectron spectroscopy and thin film-X-ray diffraction analysis of coatings show that the surface coating is mainly comprised of Mg(2)SiO(4), MgO and WO(3). Scanning electron microscopy observations have revealed that the dense and compact coating formed in the presence of tungstate has less structural imperfections in comparison to the control one fabricated without use of tungstate. The effect of oxidation time on the morphology and phase composition of coatings is also examined in detail.

  8. Microscopic insight into the origin of enhanced glass-forming ability of metallic melts on micro-alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. J.; Chathoth, S. M., E-mail: smavilac@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong (China); Podlesnyak, A. [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Mamontov, E. [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wang, W. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2015-09-28

    Extensive efforts have been made to develop metallic-glasses with large casting diameter. Such efforts were hindered by the poor understanding of glass formation mechanisms and the origin of the glass-forming ability (GFA) in metallic glass-forming systems. In this work, we have investigated relaxation dynamics of a model bulk glass-forming alloy system that shows the enhanced at first and then diminished GFA on increasing the percentage of micro-alloying. The micro-alloying did not have any significant impact on the thermodynamic properties. The GFA increasing on micro-alloying in this system cannot be explained by the present theoretical knowledge. Our results indicate that atomic caging is the primary factor that influences the GFA. The composition dependence of the atomic caging time or residence time is found to be well correlated with GFA of the system.

  9. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes for Hoop Creep Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Bimal K. Kad

    2006-04-10

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined here is iterative in nature and is intended to systematically (1) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, which will be (2) evaluated at ''in-service'' loads at service temperatures and environments. This research program is being conducted in collaboration with the DOE's Oak Ridge National

  10. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

    OpenAIRE

    A. Fattah-alhosseini; M. Sabaghi Joni

    2014-01-01

    This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated do...

  11. Benchmark 3 - Springback of an Al-Mg alloy in warm forming conditions

    Science.gov (United States)

    Manach, Pierre-Yves; Coër, Jérémy; Jégata Hervé Laurent, Anthony; Yoon, Jeong Whan

    2016-08-01

    Accurate prediction of springback is a long-standing challenge in the field of warm forming of aluminium sheets. The objective of this benchmark is to predict the effect of temperature on the springback process through the use of the split-ring test [1] with an Al-Mg alloy. This test consists in determining the residual stress state by measuring the opening of a ring cut from the sidewall of a formed cylindrical cup. Cylindrical cups are drawn with a heated die and blank-holder at temperatures of 20, 150 and 240°C. The force-displacement response during the forming process, the thickness and the earing profiles of the cup as well as the ring opening and the temperature of the blank are used to evaluate numerical predictions submitted by the benchmark participants. Problem description, material properties, and simulation reports with experimental data are summarized.

  12. Novel Bioactive Titanate Layers Formed on Ti Metal and Its Alloys by Chemical Treatments

    Directory of Open Access Journals (Sweden)

    Tadashi Kokubo

    2009-12-01

    Full Text Available Sodium titanate formed on Ti metal by NaOH and heat treatments induces apatite formation on its surface in a body environment and bonds to living bone. These treatments have been applied to porous Ti metal in artificial hip joints, and have been used clinically in Japan since 2007. Calcium titanate formed on Ti-15Zr-4Nb-4Ta alloy by NaOH, CaCl2, heat, and water treatments induces apatite formation on its surface in a body environment. Titanium oxide formed on porous Ti metal by NaOH, HCl, and heat treatments exhibits osteoinductivity as well as osteoconductivity. This is now under clinical tests for application to a spinal fusion device.

  13. Temperature influence on the global and local structure of the chromia supported nickel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pintea, Stelian; Rednic, Vasile; Marginean, Petru; Aldea, Nicolae [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Xie Yaning, E-mail: stelian.pintea@itim-cj.r [Beijing Synchrotron Radiation Facilities of Beijing Electron Positron Collider National Laboratory (China)

    2009-08-01

    The changes induced by the heat treatment on the global and the local structures of the supported nickel catalysts are investigated. The global structure parameters were obtained by processing the X-ray diffraction patterns of the samples using the Scherrer formula. The local structure parameters were determined by X-ray absorption spectra processing. Both types of measurements were carried out using synchrotron radiation. The nickel catalysts supported on chromia were prepared by coprecipitation method. The nickel/chromium atomic percent was 70/30. After preparation, the samples were thermally treated for three hours at 350, 650 and 950{sup 0}C. A strong correlation between previous catalytic activity information and the global and local structure is evidenced. Also the correlation between the nickel crystallite size and the active metal-oxide support interaction is discussed.

  14. Glass Forming Ability and Magnetic Property of Fe74Al4Sn2(PSiB)20 Amorphous Alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei-fei; ZHOU Shao-xiong

    2004-01-01

    Amorphous ribbons of Fe74Al4Sn2(PSiB)20 alloy have been synthesized by melt spinning and axial design method. The thermal properties of the amorphous ribbons have been measured by differential scanning calorimeter (DSC). The DSC results show that the Fe74Al4Sn2P12Si4B4 amorphous alloy has relatively wider supercooled liquid region with a temperature interval of 40.38 K (ΔTx=Tx-Tg). The alloys with a higher phosphorous content in the metalloid element composition triangle of Fe74Al4Sn2(PSiB)20 have high glass forming ability. The amorphous alloys also show good magnetic properties in which Fe74Al4Sn2P6.67Si6.67B6.67 alloy has a large maximum permeability (μm), Fe78Al4Sn2P3Si3B10 alloy exhibits a high square ratio (Br/B10) and Fe74Al4Sn2P4Si12B4 shows a low core loss (P0.5/1.3T). High glass forming ability and good magnetic properties make Fe74Al4Sn2(PSiB)20 amorphous alloys valuable in future research.

  15. Processing and Composition Effects on the Fracture Behavior of Spray-Formed 7XXX Series Al Alloys

    Science.gov (United States)

    Sharma, M. M.; Ziemian, C. W.; Eden, T. J.

    2010-12-01

    The fracture properties of high-strength spray-formed Al alloys were investigated, with consideration of the effects of elemental additions such as zinc, manganese, and chromium and the influence of the addition of SiC particulate. Fracture resistance values between 13.6 and 25.6 MPa (m)1/2 were obtained for the monolithic alloys in the T6 and T7 conditions, respectively. The alloys with SiC particulate compared well and achieved fracture resistance values between 18.7 and 25.6 MPa (m)1/2. The spray-formed materials exhibited a loss in fracture resistance ( K I) compared to ingot metallurgy 7075 alloys but had an improved performance compared to high-solute powder metallurgy alloys of similar composition. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. It is believed that at the slip band-grain boundary intersection, particularly in the presence of large dispersoids and/or inclusions, microvoid nucleation would be significantly enhanced. Differences in fracture surfaces between the alloys in the T6 and T7 condition were observed and are attributed to inhomogeneous slip distribution, which results in strain localization at grain boundaries. The best overall combination of fracture resistance properties were obtained for alloys with minimum amounts of chromium and manganese additions.

  16. Impedance and XPS study of benzotriazole films formed on copper, copper-zinc alloys and zinc in chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Kosec, Tadeja; Merl, Darja Kek [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova 39, 1000 Ljubljana (Slovenia); Milosev, Ingrid [Jozef Stefan Institute, Department of Physical and Organic Chemistry, Jamova 39, 1000 Ljubljana (Slovenia); Orthopaedic Hospital Valdoltra, Jadranska c. 31, 6280 Ankaran (Slovenia)], E-mail: ingrid.milosev@ijs.si

    2008-07-15

    The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole was studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper-zinc alloys and zinc metal. The surface layers formed on alloys in BTAH-inhibited solution comprised both polymer and oxide components, namely Cu(I)BTA and Zn(II)BTA polymers and Cu{sub 2}O and ZnO oxides, as proved by the in-depth profiling of the layers formed. A tentative structural model describing the improved corrosion resistance of Cu, Cu-xZn alloys and Zn in BTAH containing chloride solution is proposed.

  17. Forming a perfect cubic texture in thin copper-yttrium alloy strips during cold rolling and annealing

    Science.gov (United States)

    Schastlivtsev, V. M.; Rodionov, D. P.; Khlebnikova, Yu. V.; Akshentsev, Yu. N.; Egorova, L. Yu.; Suaridze, T. R.

    2016-03-01

    The structure of strips produced from the Cu-1 wt % Y binary alloy using cold deformation by rolling to the degree of deformation of 99%, followed by recrystallization annealing, as well as the process of texture formation in these strips, is studied. The possibility of forming a perfect cubic texture in a thin strip made of a binary yttrium-modified copper-based alloy has been shown in principle, which opens the prospect of the use of this alloy to produce substrates for strip high-temperature superconductors of the second generation. The optimum conditions of annealing have been determined, which make it possible to form a perfect biaxial texture in the Cu-1 wt % Y alloy with a content of cubic grains {001} ± 10° on the surface of the textured strip of over 95%.

  18. Glass-forming ability analysis of selected Fe-based bulk amorphous alloys

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-09-01

    Full Text Available Purpose: The paper mainly aims to present the structure and thermal stability of selected Fe-based bulk metallic glasses: Fe72B20Si4Nb4 and Fe43Co14Ni14B20Si5Nb4.Design/methodology/approach: The investigated samples were cast in form of the rods by the pressure die casting method. The structure analysis of the studied materials in as-cast state was carried out using XRD and TEM methods. The thermal stability associated with glass transition temperature (Tg, onset (Tx and peak (Tp crystallization temperature was examined by differential scanning calorimetry (DSC. Several parameters have been used to determine the glass-forming ability of studied alloys. The parameters of GFA included reduced glass transition temperature (Trg, supercooled liquid region (ΔTx, the stability (S and (Kgl parameter.Findings: The XRD and TEM investigations revealed that the studied as-cast metallic glasses were fully amorphous. Changes of the onset and peak crystallization temperature and the glass transition temperature as a function of glassy samples thickness were stated. The good glass-forming ability (GFA enabled casting of the Fe72B20Si4Nb4 and Fe43Co14Ni14B20Si5Nb4 glassy rods.Practical implications: The obtained examination results confirm the utility of applied investigation methods in the thermal stability analysis of examined bulk amorphous alloys. It is evident that parameters Trg, ΔTx, Kgl, S could be used to determine glass-forming ability of studied bulk metallic glasses.Originality/value: The success of fabrication of studied Fe-based bulk metallic glasses in form of rods with diameter up to 3 mm is important for the future progress in research of this group of materials.

  19. Selection of compositions with high glass forming ability in the Ni-Nb-B alloy system

    Directory of Open Access Journals (Sweden)

    Marcio Andreato Batista Mendes

    2012-10-01

    Full Text Available A combination of an extension of the topological instability "λ criterion" and the "average electronegativity" has been recently reported in the literature to predict compositions with high glass-forming ability (GFA. In the present work, both criteria have been applied to select the Ni61.0Nb36.0B3 alloy with a high glass-forming ability. Ingots were prepared by arc-melting and were used to produce ribbons processed by the melt-spinning technique further characterized by differential scanning calorimetry (DSC, X-ray diffraction (XRD and scanning electron microscopy (SEM. The Ni61.0Nb36.0B3 alloy revealed a complete amorphization and supercooled liquid region ΔTx = 68 K. In addition, wedge-shaped samples were prepared using copper mold casting in order to determine the critical thickness for amorphous formation. Scanning electron microscopy (SEM revealed that fully amorphous samples could be obtained, reaching up to ~800 µm in thickness.

  20. Plasma Surface Cu Alloyed Layer as a Lubricant on Stainless Steel Sheet:Wear Characteristics and On-job Performance in Incremental Forming

    Institute of Scientific and Technical Information of China (English)

    WU Hongyan; WEI Hongyu; Ghulam Hussain; TAO Kemei; Asif Iqbal; RAO Weifeng

    2016-01-01

    To solve the problems of poor forming and easy adhesion of the stainless steel, Cu alloyed layer on the stainless steels was prepared by the double glow plasma surface alloying technique. The experimental results indicated that the supersaturated copper dispersedly precipitated in grain interior and crystal boundaries and formed the vermicular structure. The tribological tests indicated that the friction coefifcient of the Cu alloyed layer was lower than that of the stainless steels. The wear rate of stainless steel in the presence of Cu alloyed layer was approximately 2-fold lower than that in the absence of the alloyed layer. The results of the incremental forming indicated that the ploughing phenomenon was not observed on the stainless steel in the presence of Cu alloyed layer during the incremental forming, while the stainless steel presented the deep ploughing. Therefore, Cu alloyed layer on stainless steel exhibited excellent self-lubrication and forming properties.

  1. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

    Directory of Open Access Journals (Sweden)

    A. Fattah-alhosseini

    2014-12-01

    Full Text Available This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated donor density increases linearly with increasing the formation potential. Also, the electrochemical impedance spectroscopy (EIS results indicated that the thickness of the passive film was decreased linearly with increasing the formation potential. The results showed that decreasing the formation potential offer better conditions for forming the passive films with higher protection behavior, due to the growth of a much thicker and less defective films.

  2. Molecular dynamics study of the ternary Cu50Ti25Zr25 bulk glass forming alloy

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available The structure and thermodynamic properties of a ternary Cu50Ti25Zr25 metallic glass forming alloy in solid-liquid to glass phases were studied using molecular dynamics (MD method based on tight-binding (TB potentials. An atomic description of the melting, glass formation and crystallization process has been analyzed using different heating and cooling rates. The computed Glass Forming Ability (GFA parameters are in good agreement with experimental data. The structure analysis of the Cu50Ti25Zr25 based on molecular dynamics simulation will be also presented and compared with available MD results. We have also discussed the crystallization transition with two different interatomic potentials used in this work

  3. Nanocrystallization kinetics and glass forming ability of the Fe65Nb10B25 metallic alloy

    Science.gov (United States)

    Torrens-Serra, J.; Rodríguez-Viejo, J.; Clavaguera-Mora, M. T.

    2007-12-01

    The crystallization kinetics of glassy Fe65Nb10B25 melt-spun ribbons is studied by differential scanning calorimetry in the mode of continuous heating and isothermal annealing and by x-ray diffraction and transmission electron microscopy. Continuous heat treatments of the ribbons show the presence of multiple exothermic peaks before melting. The low-temperature peak corresponds to the precipitation of nanoscale Fe23B6 -type crystalline metastable phase, and further annealing leads to its transformation into the metastable Fe3B phase and subsequent formation of bcc-Fe , Fe2B , and FeNbB stable crystalline phases. The nucleation frequency and the growth rate are determined at selected temperatures from the analysis of the microstructures that emerge during the Fe23B6 -type nanocrystallization. The master curve method is used to obtain the apparent activation energy and the Avrami exponent at the nanocrystallization onset. The nanocrystallization kinetics is explained in the framework of the Kolmogorov-Johnson-Mehl-Avrami theory. The rejection of insoluble alloy atoms during primary crystallization, the formation of diffusion layers around the crystals, and the decrease in the nucleation frequency caused by alloy enrichment of the residual disordered matrix is modeled through a soft impingement factor. Estimated values for the interfacial energy that provide a satisfactory agreement between experiments and modeling are derived considering that homogeneous nucleation frequency and interface-controlled grain growth are dominant at the onset of the nanocrystallization. Consequently, the time-temperature-transformation diagram is also drawn and the critical cooling rate estimated for this glass forming alloy.

  4. Preliminary Study on Some Properties of Co-Cr Dental Alloy Formed by Selective Laser Melting Technique

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; HUANG Qirong; GAO Yang; LUO Peng; ZHAO Chuang

    2012-01-01

    The surface condition,some properties and ion releasing behavior of cobalt-chromium (Co-Cr)dental alloy formed by selective laser melting (SLM) technique were investigated.Before porcelain fused firing,the surface condition of the Co-Cr alloy was observed using a scanning electron microscope (SEM),and then the density and hardness were examined.After porcelain fused firing,the interface of porcelain and alloy was observed,and then the metal-ion release of the samples was tested.SLM technique provides Co-Cr alloy higher hardness than casting method.After degassing-oxidation procedure and porcelain fused firing,the interface of the alloy and porcelain showed excellent combination.Co ion was more than Cr ion released from SLM Co-Cr alloy,the amounts of Co and Cr ions were safe according to ISO security criterion.Considering the properties before and after porcelain fused sintering process,SLM technique is suitable for dental Co-Cr alloy restoration.

  5. Photodeposition of copper and chromia on gallium oxide: the role of co-catalysts in photocatalytic water splitting.

    Science.gov (United States)

    Busser, G Wilma; Mei, Bastian; Pougin, Anna; Strunk, Jennifer; Gutkowski, Ramona; Schuhmann, Wolfgang; Willinger, Marc-Georg; Schlögl, Robert; Muhler, Martin

    2014-04-01

    Split second: The photocatalytic activity of gallium oxide (β-Ga2 O3) depends strongly on the co-catalysts CuOx and chromia, which can be efficiently deposited in a stepwise manner by photoreduction of Cu(2+) and CrO4 (2-). The water-splitting activity can be tuned by varying the Cu loading in the range 0.025-1.5 wt %, whereas the Cr loading is not affecting the rate as long as small amounts (such as 0.05 wt %) are present. Chromia is identified as highly efficient co-catalyst in the presence of CuOx : it is essential for the oxidation of water.

  6. Characterization of oxide films formed on magnesium alloys using bipolar pulse microarc oxidation in phosphate solutions

    Institute of Scientific and Technical Information of China (English)

    WANG Li-shi; CAI Qi-zhou; WEI Bo-kang; LIU Quan-xin

    2005-01-01

    The surface morphology and chemical composition of the oxide films formed on pure magnesium and AZ91D alloy in aqueous electrolytes which contained sodium hexafluorinealuminate(Na3 AlF6), potassium hydroxide (KOH), sodium hexametahposphate ((NaPO3)6), and triethanolamine were investigated by X-ray diffraction (XRD), scanning electron microscope(SEM) and energy dispersive spectroscopy(EDX). The results show that the input of the negative pulse has great influences on the quantity and the appearance of the microdischarges. Three types of pores can be distinguished on the surface of the oxide film and their size ranges are 0.5 - 1 μm, 1 -2μm and 4- 7 μm, respectively. A few microcracks are seen around the large pores. There exists a remarkable fluorideenriched zone of about 4 -6 μm for pure magnesium and 3 -5 μm for AZ91D alloy at the coating/substrate interface.

  7. Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

    Directory of Open Access Journals (Sweden)

    A.R. Mirak

    2015-09-01

    Full Text Available In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.

  8. Localization model description of diffusion and structural relaxation in glass-forming Cu-Zr alloys

    Science.gov (United States)

    Douglas, Jack F.; Pazmino Betancourt, Beatriz A.; Tong, Xuhang; Zhang, Hao

    2016-05-01

    We test the localization model (LM) prediction of a parameter-free relationship between the α-structural relaxation time τ α and the Debye-Waller factor    for a series of simulated glass-forming Cu-Zr metallic liquids having a range of alloy compositions. After validating this relationship between the picosecond (‘fast’) and long-time relaxation dynamics over the full range of temperatures and alloy compositions investigated in our simulations, we show that it is also possible to estimate the self-diffusion coefficients of the individual atomic species (D Cu, D Zr) and the average diffusion coefficient D using the LM, in conjunction with the empirical fractional Stokes-Einstein (FSE) relation linking these diffusion coefficients to τ α . We further observe that the fragility and extent of decoupling between D and τ α strongly correlate with    at the onset temperature of glass-formation T A where particle caging and the breakdown of Arrhenius relaxation first emerge.

  9. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [ORNL; Yamamoto, Yukinori [ORNL; Brady, Michael P [ORNL; Pint, Bruce A [ORNL; Pankiw, Roman [Duraloy Technologies Inc; Voke, Don [Duraloy Technologies Inc

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  10. 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.

  11. Effect of Aluminium Addition on Glass Forming Ability of Nd55-xAl10+xFe15Co20 (x=0, 5, 10) Alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nd55-xAl10+xCo20Fe15 (x=0, 5, 10) bulk glass-forming alloys with distinct glass transition in differential scanning calorimetry (DSC) traces were obtained by suction casting. The glass forming ability (GFA) of the alloys was investigated. It was found that the reduced glass transition temperature (Trg) and the parameter γ of the alloys increased with the increasing concentration of Al. The glass formation enthalpy of the alloys was calculated based on Miedema′s model, and it was suggested that the GFA of the alloys could be enhanced by the decrease of the glass formation enthalpy with Al additions.

  12. Biomedical Titanium alloy prostheses manufacturing by means of Superplastic and Incremental Forming processes

    Directory of Open Access Journals (Sweden)

    PiccininniAntonio

    2016-01-01

    Full Text Available The present work collects some results of the three-years Research Program “BioForming“, funded by the Italian Ministry of Education (MIUR and aimed to investigate the possibility of using flexible sheet forming processes, i.e. Super Plastic Forming (SPF and Single Point Incremental Forming (SPIF, for the manufacturing of patient-oriented titanium prostheses. The prosthetic implants used as case studies were from the skull; in particular, two different Ti alloys and geometries were considered: one to be produced in Ti-Gr23 by SPF and one to be produced in Ti-Gr2 by SPIF. Numerical simulations implementing material behaviours evaluated by characterization tests were conducted in order to design both the manufacturing processes. Subsequently, experimental tests were carried out implementing numerical results in terms of: (i gas pressure profile able to determine a constant (and optimal strain rate during the SPF process; (ii tool path able to avoid rupture during the SPIF process. Post forming characteristics of the prostheses in terms of thickness distributions were measured and compared to data from simulations for validation purposes. A good correlation between numerical and experimental thickness distributions has been obtained; in addition, the possibility of successfully adopting both the SPF and the SPIF processes for the manufacturing of prostheses has been demonstrated.

  13. Glass forming ability and thermodynamic properties of Ti(Zr,Hf)NiCu shape memory alloys

    Science.gov (United States)

    Pasko, A.; Kolomytsev, V.; Babanly, M.; Sezonenko, A.; Ochin, P.; Portier, R.; Vermaut, Ph.

    2003-10-01

    Rapidly solidified amorphous and crystalline-amorphous ribbons have been produced from a number of quatemary Ti{50+z-x}(Zr,Hf){ x}Ni{50- z-y}Cu{ y} alloys where z =(-5, 0, 5). Structural states were checked by XRD, crystallization behaviour of amorphous phase and martensitic transformations in crystalline material were studied by DSC. The glass transition and crystallization temperatures have been measured at different heating rates, and the crystallization activation energy for each composition and heat event bas been calculated. Isothermal crystallization gives an alternative method of determining the activation energy according to the Arrhenius equation. Contradictory requirements for the conditions of martensitic transformation and good glass forming ability is discussed.

  14. Microstructures variation of spray formed Si-30%Al alloy during densification process

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-guang; XIONG Bai-qing; ZHANG Yong-an; LIU Hong-wei; WANG Feng; ZHU Bao-hong

    2006-01-01

    Microstructure variation of spray-formed Si-30%Al alloy during densification process by hot pressing was studied. The results indicate that the microstructure of as-deposited preforms is fine and homogenous. The primary silicon phases distributing in aluminium matrix evenly are fine and irregular. Aluminium matrix is divided into two groups: supersaturated α-Al phase or α-Al phase and Al-Si pseudo-eutectic phase or Al-Si eutectic phase. During hot pressing, the primary silicon and the aluminium matrix realign as follows: the primary silicon fractures at a given compressive stress, the particles congregates in microzone with increasing stress, and the aluminium matrix flows and connects in harness. Al-Si pseudo-eutectic phase turns into Al-Si eutectic phase due to the diffusion of atoms during densification process.

  15. A thermodynamic approach towards glass-forming ability of amorphous metallic alloys

    Indian Academy of Sciences (India)

    Sonal R Prajapati; Supriya Kasyap; Arun Pratap

    2015-12-01

    A quantitative measure of the stability of a glass as compared to its corresponding crystalline state can be obtained by calculating the thermodynamic parameters, such as the Gibbs free energy difference (), entropy difference () and the enthalpy difference () between the super-cooled liquid and the corresponding crystalline phase. is known as the driving force of crystallization. The driving force of crystallization () provides very important information about the glass-forming ability (GFA) of metallic glasses (MGs). Lesser the driving force of crystallization more is the GFA. The varies linearly with the critical size (). According to Battezzati and Garonne the parameter ( = (1−(/))/(1−( / ))) in the expression for should be a constant (i.e., 0.8), but its uniqueness is not observed for all MGs. The thermal stability of various alloy compositions is studied by their undercooled liquid region ( = − ). Large implies greater stability against crystallization of the amorphous structure. Other GFA parameters are also calculated and correlated with critical size ().

  16. The influence of Mg content and impurities in AA5083 alloy on the properties of flow formed tubes

    Directory of Open Access Journals (Sweden)

    Milutin Nikačević

    2013-12-01

    Full Text Available Microstructure and mechanical properties of flow formed thin-walled tubes of AA5083 alloy from two metallurgical heats are presented. The influence of the chemical composition and applied reduction on the surface features and residual macro stresses were also studied. The residual macro stresses were estimated by ring method. The heat with higher content of alloying elements and impurities (Mg, Mn, Fe, Si had higher strength of preforms as well as flow formed tubes. These tubes exhibit three times higher residual stresses, lower spinnability, and the large amount of the surface defects (microcracks. This behaviour is attributed to the inhomogeneous material flow during deformation and presence of impurities.

  17. Material characterization and finite element simulations of aluminum alloy sheets during non-isothermal forming process

    Science.gov (United States)

    Zhang, Nan

    The utilization of more non-ferrous materials is one of the key factors to succeed out of the constantly increasing demand for lightweight vehicles in automotive sector. Aluminum-magnesium alloys have been identified as the most promising substitutions to the conventional steel without significant compromise in structural stiffness and strength. However, the conventional forming methods to deform the aluminum alloy sheets are either costly or insufficient in formability which limit the wide applications of aluminum alloy sheets. A recently proposed non-isothermal hot stamping approach, which is also referred as Hot Blank - Cold Die (HB-CD) stamping, aims at fitting the commercial grade aluminum alloy sheets, such as AA5XXX and AA7XXX, into high-volume and cost-effective production for automotive sector. In essence, HB-CD is a mutation of the conventional hot stamping approach for boron steel (22MnB5) which deforms the hot blank within the cold tool set. By elevating the operation temperature, the formability of aluminum alloy sheets can be significantly improved. Meanwhile, heating the blank only and deforming within the cold tool sets allow to reduce the energy and time consumed. This research work aims at conducting a comprehensive investigation of HB-CD with particular focuses on material characterization, constitutive modeling and coupled thermo-mechanical finite element simulations with validation. The material properties of AA5182-O, a popular commercial grade of aluminum alloy sheet in automotive sector, are obtained through isothermal tensile testing at temperatures from 25° to 300°, covering a quasi-static strain-rate range (0.001--0.1s-1). As the state-of-the-art non-contact strain measurement technique, digital image correlation (DIC) system is utilized to evaluate the stress-strain curves as well as to reveal the details of material deformation with full-field and multi-axis strain measurement. Material anisotropy is characterized by extracting the

  18. Surface structure of crystalline and amorphous chromia catalysts for the selective catalytic reduction of nitric oxide. 2. Diffuse reflectance FTIR study of thermal treatment and oxygen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Schraml-Marth, M.; Wokaun, A. (Univ. of Bayreuth (Germany)); Curry-Hyde, H.E.; Baiker, A. (Swiss Federal Inst. of Tech., Zuerich (Switzerland))

    1992-02-01

    The activation of crystalline and amorphous chromia surfaces by thermal pretreatment in argon and oxygen adsorption at 473 K has been studied by diffuse reflectance FTIR and Raman spectroscopy. The formation of coordinatively unsaturated chromium sites during thermal activation is monitored by observing the evolution of Cr{double bond}O stretching absorptions both in the fundamental and overtone regions of the FTIR spectrum. On {alpha}-Cr{sub 2}O{sub 3}, labile surface oxygen species are largely removed at 498 K, whereas on the amorphous chromia surface, labile oxygen is more tightly bound. As a consequence, coordinatively unsaturated chromium sites are generated on amorphous chromia to a lesser extent than on {alpha}-Cr{sub 2}O{sub 3}. Upon high-temperature oxygen treatment, O{sub 2} is dissociatively adsorbed. Coordinatively unsaturated sites are occupied by the added oxygen, as manifested by an increase in the number of Cr{double bond}O oscillators. Fine structure in the Cr{double bond}O absorptions of the amorphous chromia is observed for the first time, and is tentatively assigned to various types of surface sites. Raman spectroscopic characterization of the amorphous chromia surface reveals laser-induced dehydration and creation of coordinatively unsaturated surface Cr{double bond}O sites, accompanied by progressive crystallization of the amorphous substrate. Differences between crystalline and amorphous chromia with respect to their SCR activity are correlated with the higher density of labile oxygen species available on the surface of amorphous chromia under SCR reaction conditions (423-473 K).

  19. Pack Aluminide Coatings Formed at 650℃ for Enhancing Oxidation Resistance of Low Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    Z.D.Xiang; S.R.Rose; P.K.Datta

    2004-01-01

    This study aims to investigate the feasibility of forming iron aluminide coatings on a commercial 9Cr-1Mo (wt.%) alloy steel by pack cementation at 650℃ in an attempt to improve its high temperature oxidation resistance. Pack powders containing Al, Al2O3 and a series of halide salts were used to carry out the coating deposition experiments, which enabled identification of the most suitable activator for the pack aluminising process at the intended temperature. The effect of pack aluminium content on the growth kinetics and microstructure of the coatings was then studied by keeping deposition conditions and pack activator content constant while increasing the pack aluminium content from 1.4 wt.% to 6 wt.%. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were used to analyse the phases and microstructures of the coatings formed and to determine depth profiles of coating elements in the coating layer. Oxidation resistance of the coating was studied at 650 ~C in air by intermittent weight measurement at room temperature. It was observed that the coating could substantially enhance the oxidation resistance of the steel under these testing conditions, which was attributed to the capability of the iron aluminide phases to form alumina scale on the coating surface through preferential A1 oxidation.

  20. Pack Aluminide Coatings Formed at 650 ℃ for Enhancing Oxidation Resistance of Low Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    Z. D. Xiang; S. R. Rose; P. K. Datta

    2004-01-01

    This study aims to investigate the feasibility of forming iron aluminide coatings on a commercial 9Cr-lMo (wt.%)alloy steel by pack cementation at 650 ℃ in an attempt to improve its high temperature oxidation resistance. Pack powders containing Al, Al2O3 and a series of halide salts were used to carry out the coating deposition experiments, which enabled identification of the most suitable activator for the pack aluminising process at the intended temperature. The effect of pack aluminium content on the growth kinetics and microstructure of the coatings was then studied by keeping deposition conditions and pack activator content constant while increasing the pack aluminium content from 1.4 wt.% to 6 wt.%. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were used to analyse the phases and microstructures of the coatings formed and to determine depth profiles of coating elements in the coating layer. Oxidation resistance of the coating was studied at 650 ℃ in air by intermittent weight measurement at room temperature. It was observed that the coating could substantially enhance the oxidation resistance of the steel under these testing conditions, which was attributed to the capability of the iron aluminide phases to form alumina scale on the coating surface through preferential Al oxidation.

  1. Existing form and effect of zirconium in pure Mg, Mg-Yb, and Mg-Zn-Yb alloys

    Institute of Scientific and Technical Information of China (English)

    YU Wenbin; HE Hong; LI Chunmei; LI Qing; LIU Zhiyi; QIN Bing

    2009-01-01

    The existing form and grain refining effects of small zirconium addition in pure Mg, Mg-Yb and Mg-Zn binary alloys, and Mg-Zn-Yb ternary alloy (ZK60-Yb) were investigated. The results show that Zr element exists mainly in single and cluster particles of pure α-Zr or Zn-Zr compounds inside grains and at grain boundaries. Only the particles located in the interior of grains can act as the nucleus for α-Mg growth and effectively promote the formation of Fine equiaxed grains. The broken and dispersed Zr-rich particles produced during the hot extrusion process can form nebulous banded structure in which these free particles may act as obstacles to dislocation motion in wrought magnesium alloys.

  2. Forming of Hollow Shaft Forging From Titanium Alloy Ti6Al4V by Means of Rotary Compression

    Directory of Open Access Journals (Sweden)

    Tomczak J.

    2015-04-01

    Full Text Available This paper presents chosen results of theoretical-experimental works concerning forming of hollow shafts forgings from titanium alloys, which are applied in aviation industry. At the first stage of conducted analysis, the forging forming process was modeled by means of finite element method. Calculations were made using software Simufact Forming. On the basis of performed simulations optimal parameters of rotary compression process were determined. Next, experimental tests of forging forming in laboratory conditions were made. For the research needs, a forging aggregate, designed by the Authors, was used. Conducted research works confirmed the possibility of metal forming (by means of rotary compression of hollow shafts from hard workable titanium alloys. Numerous advantages of rotary compression process, make it attractive both for low series production (aircraft industry and for mass production (automotive industry.

  3. Alloy

    Science.gov (United States)

    Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

    2014-07-01

    The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by α-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 μm in the extruded ingot, down to 1.6 μm for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

  4. Wetting of WC by a Zr-base metallic glass-forming alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, Changchun 130025 (China); Zheng, Xiao-Hong [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, Changchun 130025 (China); Liu, Hui-Jie [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Qi-Chuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, Changchun 130025 (China)

    2013-05-15

    Wetting of hot-pressed polycrystalline WC substrates by a Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} bulk metallic glass (BMG)-forming alloy was investigated at 1133–1253 K in a high vacuum using a modified sessile drop method. The alloy melt spread rapidly on the WC surface, reaching no more than 30° within 3 s, and then slowly (at T < 1213 K) or even remained steady (at T ≥ 1213 K) in the subsequent isothermal dwelling stage. The final equilibrium contact angles were between 11° and 20°, slightly increasing with rising temperature and thus presenting an appreciably anomalous temperature-dependent behavior. The reaction between WC and the Zr-base melt was moderate, slightly enhancing with increasing temperature, and yielded W, ZrC and W{sub 5}Zr{sub 3} at the interface. The wetting, in principle, was driven by the formation of a precursor film in front of the triple line as a result of the adsorption of active atoms (primarily Zr) rather than by the interfacial reaction. From the viewpoint of the wettability and reactivity, WC is a good reinforcement for the preparation of the Zr-base BMG matrix composites. - Highlights: ► WC shows good wettability and moderate reactivity with the Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} melt. ► The final wettability exhibits slightly anomalous dependence on temperature. ► The interfacial reaction yields ZrC, W and W{sub 5}Zr{sub 3} phases. ► The primary driving force for the wetting is the formation of the precursor film in front of the triple line.

  5. Stresses and Cracking During Chromia-Spinel-NiO Cluster Formation in TBC Systems

    Science.gov (United States)

    Eriksson, Robert; Gupta, Mohit; Broitman, Esteban; Jonnalagadda, Krishna Praveen; Nylén, Per; Lin Peng, Ru

    2015-08-01

    Thermal barrier coatings (TBC) are used in gas turbines to reduce the temperatures in the underlying substrate. There are several mechanisms that may cause the TBC to fail; one of them is cracking in the coating interface due to extensive oxidation. In the present study, the role of so called chromia-spinel-NiO (CSN) clusters in TBC failure was studied. Such clusters have previously been found to be prone to cracking. Finite element modeling was performed on a CSN cluster to find out at which stage of its formation it cracks and what the driving mechanisms of cracking are. The geometry of a cluster was obtained from micrographs and modeled as close as possible. Nanoindentation was performed on the cluster to get the correct Young's moduli. The volumetric expansion associated with the formation of NiO was also included. It was found that the cracking of the CSN clusters is likely to occur during its last stage of formation as the last Ni-rich core oxidizes. Furthermore, it was shown that the volumetric expansion associated with the oxidation only plays a minor role and that the main reason for cracking is the high coefficient of thermal expansion of NiO.

  6. Electrochemical and biological characterization of coatings formed on Ti-15Mo alloy by plasma electrolytic oxidation.

    Science.gov (United States)

    Kazek-Kęsik, Alicja; Krok-Borkowicz, Małgorzata; Pamuła, Elżbieta; Simka, Wojciech

    2014-10-01

    β-Type titanium alloys are considered the future materials for bone implants. To improve the bioactivity of Ti-15Mo, the surface was modified using the plasma electrolytic oxidation (PEO) process. Tricalcium phosphate (TCP, Ca3PO4), wollastonite (CaSiO3) and silica (SiO2) were selected as additives in the anodizing bath to enhance the bioactivity of the coatings formed during the PEO process. Electrochemical analysis of the samples was performed in Ringer's solution at 37°C. The open-circuit potential (EOCP) as a function of time, corrosion potential (ECORR), corrosion current density (jCORR) and polarization resistance (Rp) of the samples were determined. Surface modification improved the corrosion resistance of Ti-15Mo in Ringer's solution. In vitro studies with MG-63 osteoblast-like cells were performed for 1, 3 and 7 days. After 24h, the cells were well adhered on the entire surfaces, and their number increased with increasing culture time. The coatings formed in basic solution with wollastonite exhibited better biological performance compared with the as-ground sample.

  7. Growth and Corrosion Characteristics of Plasma Electrolytic Oxidation Ceramic Films Formed on AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    王丽; 陈砺; 严宗诚; 王红林; 彭家志

    2009-01-01

    The growth characteristics of oxide ceramic films formed on AZ31 magnesium alloy with plasma electrolytic oxidation(PEO)technique in alkaline silicate solution Were investigated.The composition,slructure and morphology of the coatings were detected by energy dispersive X-ray spectroscope and scanning electron microscope.The amount of dissolved magnesium in the electrolytes during PEO process was measured by atomic absorption spectrometry.The results indicated that the growth process of PEO films had three stages when applied with constant voltage mode.In the first stage,the growth rate of PEO films was low,and concentrations of elements O.Mg and Si varied slightly.Atter sparking occurred(the second stage).the PEO films showed higher growth rate due to the high transfer rate of ionS and electrons,and the existoncc of plasma reactions.When the growth rate tended to maintain stable with time,the third stage happened.PEO films exhibited different uniform and pitting.corrosion characteristiCS in difierent reaction stages.The films formed at 300 V for 30 min performed best corrosion resistance and the phase of ceramic films was mainly composed of MgSiO3 and forsterite Mg2SiO4.

  8. Material modelling for creep-age forming of aluminium alloy 7B04

    Directory of Open Access Journals (Sweden)

    Lam Aaron C.L.

    2015-01-01

    Full Text Available This paper presents a study on the creep-ageing behaviour of a peak-aged aluminium alloy 7B04 under different tensile loads at 115oC and subsequently modelling it for creep-age forming (CAF applications. Mechanical properties and microstructural evolutions of creep-aged specimens were investigated. The material was modelled using a set of unified constitutive equations, which not only captures the material's creep deformation but also takes into account yield strength contributions from solid solution hardening, age hardening and dislocation hardening during creep-ageing. A possible application of the present work is demonstrated by implementing the determined material model into a commercial finite element analysis solver via a user-defined subroutine for springback prediction of creep-age formed plates. A good agreement is observed between the simulated springback values and experimental results. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.

  9. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystals and Polytetrahedral-Phase-Forming Alloys

    Science.gov (United States)

    Kelton, K. F.; Gangopadhyay, A. K.; Lee, G. W.; Hyers, R. W.; Rogers, J. R.; Robinson, M. B.; Rathz, T. J.; Krishnan, S.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The local atomic structures of undercooled liquid metals are presumed to be icosahedral; this order is incompatible with translational periodicity, constituting a barrier to the nucleation of the crystal phase. The extended atomic structure of the icosahedral quasicrystal (i-phase) is similar to that presumed in the undercooled liquid. Therefore, a comparison of the maximum undercooling in alloys that form the i-phase with those that form crystal phases provides a probe of the liquid structure.

  10. The behaviour of entrainment defects formed in commercial purity Mg alloy cast under a cover gas of SF6

    Science.gov (United States)

    Li, T.; Griffiths, W. D.

    2016-03-01

    In the casting of light alloys, the oxidised film on the melt surface can be folded due to surface turbulence, thus forming entrainment defects that have a significant negative effect on the mechanical properties of castings. Previous researchers reported that the surface film of Mg alloys formed in an atmosphere containing SF6 had a complicated structure composed of MgO and MgF2. The work reported here aims to investigate the behaviour of entrainment defects formed in magnesium alloys protected by SF6-containing atmospheres. Tensile test bars of commercial purity Mg were cast in an unsealed environment under a cover gas of pure SF6. 34Scanning electron microscopy (SEM) of the fracture surface of the test bars indicated entrainment defects that consisted of symmetrical films containing MgO, but also sulphur and fluorine. The results of these examinations of the symmetrical films were used to infer the potential formation and development of entrainment defects in commercial purity Mg alloy.

  11. Composition and hardness of mullite coatings formed with direct current power supply on LY12 aluminum alloy surface

    Institute of Scientific and Technical Information of China (English)

    XIN Shi-gang; JIANG Zhao-hua; LI Yan-ping; ZHANG Ji-lin

    2005-01-01

    The surface modification of aluminum and its alloys using plasma technology is increasingly being investigated. Thick ceramic coatings with high hardness on aluminum alloys can be prepared successfully using a micro-plasma oxidation (MPO) technique. In this work, the composition, microstructure and elemental distribution of ceramic coatings formed by MPO on LY 12 aluminum alloy and its hardness are investigated using XRD, EPMA and microhardness instruments. The results show that the ceramic coatings consist of mullite, γ -Al2 O3 and a lot of amorphous matter. The content of silicon in the coatings increases from interface to the coatings, however, the content of aluminum decreases along this direction. The maximum hardness of ceramic coatings is up to 9. 2 GPa.

  12. Characterization of plasma electrolytic oxide formed onAZ91 Mg alloy in KMnO4 electrolyte

    Institute of Scientific and Technical Information of China (English)

    Duck-Young HWANG; Ki-Ryong SHIN; Bongyoung YOO; Dong-Heon LEE; Deok-Yong PARK; Dong-Hyuk SHIN

    2009-01-01

    The aim of this work is to investigate microstructure, corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution. There are lots of closed pores that are filled with another oxide compound compared with the typical surface morphology with pore coated until 350 V of coating voltage. The thickness of oxide layer increases with increasing coating voltage. The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium permanganate consists of MgO and Mn2O3. Corrosion potential of the oxide layer on AZ91 Mg alloy obtained at different plasma electrolytic oxidation(PEO) reaction stages increases with increasing coating voltage. The corrosion resistance of AZ91 Mg alloy depends on the existence of the manganese oxide in the oxide layer. The inner barrier layer composed of the MgO and Mn2O3 may serve as diffusion barrier to enhance the corrosion resistance and may partially explain the excellent anti-corrosion performance in corrosion test. Nanohardness values increase with increasing coating voltage. The increase in the nanohardness may be due to the effect of manganese oxide in the oxide layer on AZ91 Mg alloy coated from electrolyte containing KMnO4.

  13. Size-dependent structure and magnetocaloric properties of Fe-based glass-forming alloy powders

    Directory of Open Access Journals (Sweden)

    Qiang Luo

    2016-04-01

    Full Text Available We investigated the influence of particle size on the microstructure and magnetocaloric effect of Fe-based alloy powders (11 μm to 100 μm in diameter. The degree of structure order varies with the powder size. The 11 μm to 18 μm powders show the largest peak magnetic entropy change (MEC. Increasing the degree of structure order tends to decrease the maximum MEC. Nevertheless, enhancement of refrigerant capacity and MEC (above 70 K is achieved when the crystalline phase content is ∼50% (above 75 μm in the 75 μm to 100 μm powders. Exponent n of the field dependence of MEC increases with the decrease in powder size above 22.5 K. The size dependence of the structure and properties is associated with the fact that a larger particle has a slower cooling rate and takes a longer time to form medium-to-long range ordered structures.

  14. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystals and Polytetrehedral-Phase-Forming Alloys

    Science.gov (United States)

    2003-01-01

    By investigating the properties of quasicrystals and quasicrystal-forming liquid alloys, we may determine the role of ordering of the liquid phase in the formation of quasicrystals, leading to a better fundamental understanding of both the quasicrystal and the liquid. A quasicrystal is solid characterized by a symmetric but non-periodic arrangement of atoms, usually in the form of an icosahedron (12 atoms, 20 triangular faces). It is theorized that the short-range order in liquids takes this same form. The degree of ordering depends on the temperature of the liquid, and affects many of the liquid s properties, including specific heat, viscosity, and electrical resistivity. The MSFC role in this project includes solidification studies, phase diagram determination, and thermophysical property measurements on the liquid quasicrystal-forming alloys, all by electrostatic levitation (ESL). The viscosity of liquid quasicrystal-forming alloys is measured by the oscillating drop method, both in the stable and undercooled liquid state. The specific heat of solid, undercooled liquid, and stable liquid are measured by the radiative cooling rate of the droplets.

  15. Morphological and Chemical Relationships in Nanotubes Formed by Anodizing of Ti6al4v Alloy

    Directory of Open Access Journals (Sweden)

    Kaczmarek- Pawelska A.

    2014-12-01

    Full Text Available The electrochemical formation of oxide nanotubes on the Ti6Al4V alloy has been so far difficult due to easy dissolution of vanadium reach β-phase of the two phase material. Due to the topographical heterogeneity of the anodic layer in nano and microscale at anodizing of the Ti6Al4V alloy we focused to establish the relationships between nanotube diameters on both phases of the alloy and fluorides concentration in electrolyte. We studied the effect of fluoride concentration (0.5-0.7 wt.% in 99% ethylene glycol on morphological parameters of nanotube layer on the Ti6Al4V alloy anodized at 20V for 20 min. Nanotubes with diameter ~40-50 nm ±5nm on the entire Ti6Al4V alloy surface in electrolyte containing 0.6% wt. NH4F were obtained. Microscale roughness studies revealed that nanotubular layer on α-phase is thicker than on β-phase. The annealing of nanotube layers at 600°C for 2h in air, nitrogen and argon, typically performed to improve their electrical properties, influenced chemical composition and morphology of nanotubes on the Ti6Al4V alloy. The vanadium oxides (VO2, V2O3, V2O5 were present in surface nanotube layer covering both phases of the alloy and the shape of nanotubes was preserved after annealing in nitrogen.

  16. Vacuum Plasma Spray Formed High Transition Temperature Shape Memory Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Smart materials control of aero-surfaces based on shape memory alloys (SMA) is seeing increased use for improving of future subsonic fixed wing aircraft aero-surface...

  17. Electrochemical Deposition of Si-Ca/P on Nanotube Formed Beta Ti Alloy by Cyclic Voltammetry Method.

    Science.gov (United States)

    Jeong, Yong-Hoon; Choe, Han-Cheol

    2015-08-01

    The purpose of this study was to investigate electrochemical deposition of Si-Ca/P on nanotube formed Ti-35Nb-10Zr alloy by cyclic voltammetry method. Electrochemical deposition of Si substituted Ca/P was performed by pulsing the applied potential on nanotube formed surface. The surface characteristics were observed by field-emission scanning electron microscopy, X-ray diffractometer, and potentiodynamic polarization test. The phase structure and surface morphologies of Si-Ca/P deposition were affected by deposition cycles. From the anodic polarization test, nanotube formed surface at 20 V showed the high corrosion resistance with lower value of Icorr, I300, and Ipass.

  18. Interionic pair potentials and partial structure factors of compound-forming quaternary NaSn liquid alloy: First principle approach

    Indian Academy of Sciences (India)

    Anil Thakur; P K Ahluwalia

    2007-10-01

    In this paper formulae for partial structure factors have been used to study partial structure factors of compound-forming quaternary liquid alloys by considering Hoshino's m-component hard-sphere mixture, which is based on Percus-Yevic equation of Hiroike. Formulae are applied to NaSn (Na, Sn, NaSn, Na3Sn) which is considered as a quaternary liquid mixture with the formation of two compounds simultaneously. We have compared the total structure factors for ternary and quaternary alloys with experimental total structure factors which are found to be in good agreement. This suggests that, for suitable stoichiometric composition, two compounds are formed simultaneously. The hard-sphere diameters needed have been calculated using Troullier and Martins ab-initio pseudopotentials.

  19. The Effect of Variable Blank-Holder Forces on the Formability of Aluminum Alloy Sheets during Sheet Metal Forming

    Institute of Scientific and Technical Information of China (English)

    Sun Chengzhi; Chen Guanlong; Lin Zhongqin

    2004-01-01

    In this paper, the effect of variable Blank-holder forces (VBHF) on the strain path during sheet metal forming has been investigated by numerical simulation and experiments. The formability of select aluminum alloy sheet was evaluated by theory prediction of forming limit curve based on the M-K method. The effect of different VBHF on the formability was presented. In order to verify the predictions of strain path, experiments are being carried out using a recently-built multi-points variable blank-holder forces hydraulic press. The results show that large side BHF with small comer BHF during rectangular box deep drawing can improve the formability of the selected aluminum alloy sheet

  20. Modeling and Simulation of the Microstructure Evolution of the Gas-atomized Alloy Droplets during Spray Forming

    Institute of Scientific and Technical Information of China (English)

    Jiuzhou ZHAO; Dongming LIU; Hengqiang YE

    2003-01-01

    In order to understand the solidification process of an atomized droplet and predict the fraction solidification ofdroplets with flight distance during spray forming, a numerical model based on the population dynamics approach isdeveloped to describe the microstructure evolution under the common action of the nucleation and growth of grains.The model is coupled with droplets heat transfer controlling equations and solved for Al-4.5 wt pct Cu alloy. It isdemonstrated that the numerical results describe the solidification process well.

  1. Microstructure and Deformation Behavior of Ti-10V-2Fe-3Al Alloy during Hot Forming Process

    Institute of Scientific and Technical Information of China (English)

    GUAN Renguo; ZHAO Zhanyong; Choi KS; Lee CS

    2015-01-01

    The microstructure evolution and formability of Ti-10V-2Fe-3Al alloy related to the initial microstructures and processing variables were investigated during hot forming process. The experimental results show that theα-phase growth is controlled by solute diffusion during the heat treatment processes. Four different microstructures were established by combinations of several heat treatments, and Ti-10V-2Fe-3Al alloy shows excellent formability both above and below theβ transus temperature. The alloy possesses low deformation resistance and active restoration mechanism during the deformation. A constitutive equation describing the hot deformation behavior of Ti-10V-2Fe-3Al alloy was obtained. Higher lfow stress was observed for the acicular morphology ofαphase in microstructures with large aspect ratios as compared with that of small aspect ratios. Due to the dynamic recovery in softβphase, and the dynamic recrystallization and breakage of acicularα-phase, lfow softening occurred signiifcantly during deformation. Dynamic recrystallization also occurred especially in the severely deformed regions of forged parts.

  2. Chemical short-range order domain in bulk amorphous alloy and the prediction of glass forming ability

    Institute of Scientific and Technical Information of China (English)

    HUI; Xidong(惠希东); YAO; Kefu(姚可夫); KOU; Hongchao(寇宏超); CHEN; Guoliang(陈国良)

    2003-01-01

    Short-range order domains of face central cubic Zr2Ni (F-Zr2Ni) and tetragonal Zr2Ni (T-Zr2Ni) type structure with a size about 1-3 nanometers were observed in bulk amorphous Zr52.5Cu17.9Ni14.6Al10Ti5 alloy by using HREM and nano-beam electron diffraction technique. A new thermodynamic model was formulated based on the concept of chemical short-range order (SCRO). The molar fractions of CSRO and thermodynamic properties in Ni-Zr, Cu-Zr, Al-Zr, Al-Ni, Zr-Ni-Al and Zr-Ni-Cu were calculated. According to the principle of maximum the optimum glass forming ability (GFA) compositions were predicted in binary and ternary alloys. These results were proved to be valid by the experimental data of crystallizing activation energy, ΔTx and XRD patterns. The TTT curves of Zr-Ni-Cu alloys calculated based on CSRO model shows that the lowest critical cooling rate GFA is in the order of 100 K/s, which is close to the practical cooling rate for the preparation of Zr-based BMG alloys.

  3. Finite element analysis and experiment research on aluminum alloy ladder bowl with viscous pressure forming(VPF)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The process parameters of aluminum alloy ladder bowl with viscous pressure forming and solid metal punch forming were numerically simulated by commercial finite element software DEFORM.The influence of blank holder pressure(BHP)on the formability of sheet metal was investigated.It was found that lower BHP does benefit to the distribution of thickness both with VPF and with solid punch forming.The forming force needed in VPF is bigger than that of with solid punch forming at the same stroke.The distribution of thickness with VPF is more uniform than that of with solid punch forming.Compared with solid punch forming,the damage values of workpiece at the top convex comer are lower by VPF.It was also shown that fracture tendency could be reduced with VPF,so that means the formability is improved.At the same time,aluminum alloy ladder bowl was manufactured with VPF.The results show that the simulation results are in agreement with the experimental data very well.

  4. Microstructural evolution of aluminium/Al–Ni–Sm glass forming alloy laminates obtained by Controlled Accumulative Roll Bonding

    Energy Technology Data Exchange (ETDEWEB)

    Anghelus, Adrian, E-mail: anghelus.adrian@yahoo.com; Avettand-Fènoël, Marie-Noëlle, E-mail: marie-noelle.avettand-fenoel@univ-lille1.fr; Cordier, Catherine, E-mail: catherine.cordier@univ-lille1.fr; Taillard, Roland, E-mail: roland.taillard@univ-lille1.fr

    2015-05-15

    Highlights: • Elaboration of a UFG material by controlled ARB of Al/glass forming alloy multilayers. • Effect of the crystalline or amorphous nature of the reinforcement on the formability. • Investigation of the thermo-mechanical stability of the metallic glass. - Abstract: The current work deals with the early steps of the unprecedented elaboration of aluminium/Al based glass forming alloy laminates by only accumulative rolling at room temperature. The Al{sub 1−(x+y)}Ni{sub x}Sm{sub y} metallic glass forming alloy was introduced either in its original amorphous state or after total crystallization. This change of atomic structure, and therefore of both thermal and thermo-mechanical stability and mechanical behaviour, is shown to govern at once the processing parameters, the uniformity of the laminates microstructure and the bond strength at the matrix-reinforcement interfaces. The potential of the process so as to synthesize composite materials with a stable ultrafine structure is finally outlined.

  5. Complete Maps for the Internal Oxidation of Ideal Ternary Alloys Forming Insoluble Oxides under High Oxidant Pressures

    Institute of Scientific and Technical Information of China (English)

    F.GESMUNDO; S.WANG; Y.NIU

    2009-01-01

    This paper presents an analysis of the conditions of stability of the different forms of internal oxidation of ideal ternary A-B-C alloys, where A is the most noble and C the most reactive component, forming insoluble oxide and exposed to high pressures of a single oxidant. The treatment, based on an extension to ternary alloys of Wagner's criterion for the transition from internal to external oxidation in binary alloys, allows to predict the existence of three different forms of internal oxidation. In fact, in addition to the most common kinds of internal attack, involving the coupled internal oxidation of B+C beneath external AO scales and the internal oxidation of C beneath external BO scales, a third mode, involving the internal oxidation of C beneath external scales composed of mixtures of AO+BO, becomes also possible under special conditions. A combination of the boundary conditions for the existence of these different types of internal oxidation allows to predict three different kinds of complete maps for the internal oxidation in these systems, one of which involves only two modes, while the other two involve all the three possible modes of internal oxidation.

  6. Surface morphology of highly ordered nanotube formed and laser textured beta titanium alloys.

    Science.gov (United States)

    Kim, Jae-Un; Jeong, Yong-Hoon; Choe, Han-Cheol

    2013-03-01

    The aim of the present study is to produce and characterize a well-controlled surface texture on Ti-35Nb-xHf alloys to promote osseointegration. Ti-35Nb-xHf (x = 0, 3, 7 and 15 wt.%) alloys were prepared by arc melting and heat treated for 12 hr at 1000 degrees C in an argon atmosphere and then water quenching. For surface texturing, an amplified Ti: sapphire laser system was used for generating 184 femtosecond (FS, 10(-15) sec) laser pulses with the pulse energy over 30 mJ at a 1 kHz repetition rate with a central wavelength of 800 nm. The nanotube formation was achieved by anodizing a Ti-35Nb-xHf alloy in H3PO4 electrolytes containing 0.8 wt.% NaF at room temperature. The surface morphology of nano/micro structure will enhance osseointegration and cell adhesion.

  7. The Effect of Hydrogen Annealing on the Impurity Content of Alumina-Forming Alloys

    Science.gov (United States)

    Smialek, James L.

    2000-01-01

    Previously, the effect of hydrogen annealing on increasing the adhesion of Al2O3 scales had been related to the effective desulfurization that occurred during this process. The simultaneous reduction of other impurities has now been re-examined for up to 20 impurity elements in the case of five different alloys (NiCrAl, FeCrAl, PWA 1480, Rene'142, and Rene'N5). Hydrogen annealing produced measurable reductions in elemental concentration for B, C, Na, Mg, P, K, Sr, or Sn in varying degrees for at least one and up to three of these alloys. No single element was reduced by hydrogen annealing for all the alloys except sulfur. In many cases spalling occurred at low levels of these other impurities, while in other cases the scales were adherent at high levels of the impurities. No impurity besides sulfur was strongly correlated with adhesion.

  8. INFLUENCE OF RARE EARTH DOPING ON MECHANICAL PROPERTY AND MICRO-STRUCTURE OF CHROMIA OXIDE FILM

    Institute of Scientific and Technical Information of China (English)

    JIN Huiming; FELIX Adriana

    2008-01-01

    The isothermal oxidizing kinetics of Co-40Cr alloy and its yttrium ion-implanted samples are studied at 1 000 ℃ in air by thermal-gravity analysis (TGA). Scanning electronic microscopy (SEM) is used to examine the Cr2O3 oxide film's morphology after oxidation. Acoustic emission (AE) method is used in situ for monitoring the cracking and spalling of oxide films formed on both samples during oxidizing and subsequent air-cooling stages. Theoretical model is proposed relating to the film fracture process and is used for analyzing the acoustic emission spectrum both on time domain and on AE-event number domain. It is found that yttrium implantation remarkably reduces the isothermal oxidizing rate of Co-40Cr and improves the anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement are mainly that the implanted yttrium reduced the grain size of Cr2O3 oxide, increased the high temperature plasticity of oxide film, and remarkably reduced the number and size of Cr2O3/Co-40Cr interfacial defects.

  9. Finite element analysis of stiffness and static dent resistance of aluminum alloy double-curved panel in viscous pressure forming

    Institute of Scientific and Technical Information of China (English)

    LI Yi; WANG Zhong-Jin

    2009-01-01

    The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF) was studied by finite element analysis, which mainly considers the forming process conditions. The whole simulation consisting of three stages, i.e., forming, spring-back and static dent resistance, was carried out continuously using the finite element code ANSYS. The influence of blank holder pressure (BHP) and the drawbead on the stiffness and the static dent resistance of the panels formed using VPF was analyzed. The results show that the adequate setting of the drawbead can increase the plastic deformation of the double-curved panel, which is beneficial to the initial stiffness and the static dent resistance. There is an optimum BHP range for the stiffness and the static dent resistance.

  10. Microstructure evolution of laser solid forming of Ti-A1-V ternary system alloys from blended elemental powders

    Institute of Scientific and Technical Information of China (English)

    Hua Tan; Fengying Zhang; Jing Chen; Xin Lin; Weidong Huang

    2011-01-01

    @@ Morphology evolution of prior β grains of laser solid forming (LSF) Ti-xAl-yV (x ≤ 11,y ≤ 20) alloys from blended elemental powders is investigated.The formation mechanism of grain morphology is revealed by incorporating columnar to equiaxed transition (CET) mechanism during solidification.%Morphology evolution of prior β grains of laser solid forming (LSF) Ti-xAl-yV (x ≤ 11,y ≤ 20) alloys from blended elemental powders is investigated. The formation mechanism of grain morphology is revealed by incorporating columnar to equiaxed transition (CET) mechanism during solidification. The morphology of prior β grains of LSF Ti-6Al-yV changes from columnar to equiaxed grains with increasing element V content from 4 to 20 wt.-%. This agrees well with CET theoretical prediction. Likewise, the grain morphology of LSF Ti-xA1-2V from blended elemental powders changes from large columnar to small equiaxed with increasing A1 content from 2 to 11 wt.-%. The macro-morphologies of LSF Ti-8A1-2V and Ti-11A1-2V from blended elemental powders do not agree with CET predictions. This is caused by the increased disturbance effects of mixing enthalpy with increasing A1 content, generated in the alloying process of Ti, Al, and V in the molten pool.

  11. Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

    Science.gov (United States)

    Astarita, A.; Squillace, A.; Nele, L.

    2016-01-01

    Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

  12. Thermo-mechanical Forming of Al–Mg–Si Alloys: Modeling and Experiments

    NARCIS (Netherlands)

    Kurukuri, S.; Boogaard, van den A.H.; Ghosh, M.; Miroux, A.; Barlat, F.; Moon, Y.H.; Lee, M.G.

    2010-01-01

    In an ongoing quest to realize lighter vehicles with improved fuel efficiency, deformation characteristics of the material AA 6016 is investigated. In the first part of this study, material behavior of Al–Mg–Si sheet alloy is investigated under different process (temperature and strain rate) and loa

  13. Is Cu60Ti10Zr30 a bulk glass-forming alloy?

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Saida, J.; Kato, H.

    2003-01-01

    . Nanocrystals with a significant volume fraction are randomly distributed in the amorphous matrix. The copper element is enriched in nanocrystals while a slightly high zirconium content is found in the matrix. We classify that the Cu60Ti10Zr30 alloy prepared by both of the aforementioned methods...

  14. Microstructural features induced by spray forming of a ternary Pb–Sn–Sb alloy

    Indian Academy of Sciences (India)

    V C Srivastava; Anish Upadhyaya; S N Ojha

    2000-04-01

    An alloy containing Pb–12% Sn–12% Sb with small addition of copper and arsenic was spray deposited employing two different atomization gas pressure and nozzle to substrate distances. The temperature of the spray-deposit was measured during deposition at a distance of 2 and 10 mm above the substrate-deposit interface. Thermal profile data indicated small variation in temperature with time during deposition stage whereas during post deposition stage an exponential decrease in temperature was recorded. Second phase particle size along the thickness of the deposit varied from 4 to 8 m compared to 70 to 80 m size of these particles in the as cast alloy. Maximum porosity occurred in the section of the deposit near the contact surface of the substrate and also in its peripheral regions. X-ray diffraction analysis exhibited the formation of additional Cu2Sb phase in the spray-deposit and CuSn and Cu3.3Sb phases in atomized powders compared to that of the as cast alloy. The microstructural evolution during spray deposition of this alloy is discussed.

  15. Simultaneous dehydrogenation of organic compounds and hydrogen removal by hydride forming alloys

    NARCIS (Netherlands)

    Appelman, W.J.T.M.; Kuczynski, M.; Versteeg, G.F.

    1992-01-01

    The applicability of hydrogen-absorbing metals in dehydrogenation reactions was investigated. Based on thermodynamic considerations, operating ranges were defined within which an increase of the reactant conversion can he achieved owing to an in situ hydrogen removal by the alloy. Low plateau pressu

  16. Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; HAN Jing; YU Shengxue

    2006-01-01

    In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied.The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings.Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface.There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase.And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

  17. Heat-treated microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuangyin; LIN Xin; CHEN Jing; HUANG Weidong

    2009-01-01

    The effects of heat treatment on the microstmcture and mechanical properties of laser solid forming (LSF) Ti-6Al-4V alloy were investigated. The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 which grow epitaxially from the substmte along the deposition direction (Z). Solution treatment had an important effect on the width, aspect ratio, and volume fraction of primary and secondary α laths, and aging treatment mainly affects the aspect ratio and volume fraction of pri-mary α laths and the width and volume fraction of secondary α laths. Globular α phase was first observed in LSFed samples when the sam-ples were heat treated with solution treatment (950℃, 8 h/air cooling (AC)) or with solution treatment (950℃, 1 h/AC) and aging treatment (550℃, above 8 h/AC), respectively. The coarsening and globularization mechanisms of α phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.

  18. The relationship between viscosity and glass forming ability of Al-(Ni)-Yb alloy systems

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The dynamic viscosity of Al-Yb and Al-Ni-Yb superheated melts was measured using a torsional oscillation viscometer. The results show that the temperature dependence of viscosity fits the Arrhenius law well and the fitting factors are calculated. The amorphous ribbons of these alloys were produced by the melt spinning technique and the thermal properties were characterized by using a differential scanning calorimetry (DSC). E (the activation energy for viscous flow), which reflects the change rate of viscosity, has a good negative relation with the GFA in both Al-Yb and Al-Ni-Yb systems. However, there is no direct relation between liquidus viscosity (ηL) and GFA. The superheated fragility M can predict GFA in Al-Yb or Al-Ni-Yb alloy system.

  19. Molecular dynamics study of structure and glass forming ability of Zr70Pd30 alloy

    Science.gov (United States)

    Celtek, Murat; Sengul, Sedat; Domekeli, Unal; Canan, Cem

    2016-03-01

    In this study, the temperature effects on the structural evolution of the Zr70Pd30 binary alloy in the glassy and liquid states were studied using the molecular dynamics simulations based on the many-body type tight-binding potential. We considered the following properties in detail: the temperature dependence of the volume, the partial and total pair distribution functions and the simulated glass transition temperature. The effects of the cooling rates on the glass transition temperature were examined. The Wendt-Abraham parameter was calculated to determine the glass transition temperature of Zr70Pd30 glassy alloy. The pair analysis technique of Honeycutt-Andersen was applied to define local atomic arrangements produced from molecular dynamics simulations. The results show that the icosahedral ordering in glassy state has been composed during quenching period, and the simulated glass transition temperature and the total pair distribution functions are in good agreement with the experimental data.

  20. Structure and properties of ceramic coatings formed on aluminum alloys by microarc oxidation

    Institute of Scientific and Technical Information of China (English)

    LIU Wan-hui; BAO Ai-lian; LIU Rong-xiang; WU Wan-liang

    2006-01-01

    The thick and hard ceramic coatings were deposited on 2024 Al alloy by microarc oxidation in the electrolytic solution.Microstructure, phase composition and wear resistance of the oxide coatings were investigated by SEM, XRD and friction and wear tester. The microhardness and thickness of the oxide coatings were measured. The results show that the ceramic coating is mainly composed of α-Al2O3 and γ-Al2O3. During oxidation, the temperature in the microarc discharge channel is very high to make the local coating molten. From the surface to interior of the coating, microhardness increases gradually. The microhardness of the ceramic coating is HV1 800, and the microarc oxidation coatings greatly improve the antiwear properties of aluminum alloys.

  1. Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

    Science.gov (United States)

    Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

    2011-01-01

    Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

  2. 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.

  3. Microstructural Features and Mechanical Properties Induced by the Spray Forming and Cold Rolling of the Cu-13.5 wt pct Sn Alloy

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng WANG; Jiuzhou ZHAO; Jie HE; Jiangtao WANG

    2008-01-01

    Copper alloys with high strength and high conductivity are an important functional material with full of potential applications. In the present investigation, a bronze with higher tin content (Cu-13.5 wt pct Sn)was prepared successfully by spray forming, the feasibility of cold rolling this alloy was investigated, and the cold rolling characteristics of this alloy have also been discussed. The results indicate that the spray-formed Cu-13.5 wt pct Sn alloy, compared with the as-cast ingot, shows a quite fine and homogeneous single-phase structure, and, therefore shows an excellent workability. It can be cold-rolled with nearly 15% reduction in the thickness per pass and the total reduction can reach 80%. The classical border between the wrought and cast alloys is shifted to considerably higher tin contents by spray forming. After proper thermo-mechanical treatment, spray-formed Cu-13.5 wt pct Sn alloy exhibits excellent comprehensive mechanical properties.Particularly, it shows a low elastic modulus (~88 GPa) and a high flow stress (over 800 MPa) after cold forming. This combination of properties is unique in the domain of metallic materials and could open new possibilities in spring technology field.

  4. Effect of Zr Addition on Glass-Forming Ability and Magnetic Properties of Fe-Nd-Al-B Alloys Prepared by Suction Casting

    Institute of Scientific and Technical Information of China (English)

    BAI Qin; XU Hui; TAN Xiao-Hua; MENG Tao

    2009-01-01

    The microstructure and magnetic behaviors of the Fe--Nd-AI-B alloys prepared by suction casting with zirconium addition are investigated. With the small amount of zirconium addition, the magnetic properties of the alloys change from hard magnetic property to soft magnetic property. The proper addition of Zr (6%) not only improves the glass forming ability, but also suppresses the crystallization. From the scanning electron microscopy of the [(Fe0.53Nd0.37Al0.10)0.96B0.04]94Zr6 alloy and the local average elemental compositions determined using energy dispersive spectroscopy analysis, the amorphous phase with a composition of Fe47Nd38Al12Zr3 in the alloy can be observed. The bulk amorphous Fe47Nd38Al12Zr3 alloy is prepared by suction casting exhibiting good glassforming ability and soft magnetic behavior.

  5. Superplastic forming of the Cd-17.4Zn alloy; Conformado superplastico de la aleacion Cd-17.4Zn

    Energy Technology Data Exchange (ETDEWEB)

    Llanes-Briceno, J. A.; Torres-Villasenor, G. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2000-06-01

    In the present work the necessary steps to carry on the superplastic forming of the Cd-17.4Zn alloy are defined. The use of either atmospheric pressure or gas pressure as forming tools is analyzed. The optimum values of the variable involved (temperature, maximum strain and sensitivity index) are determined while a method for the characterization of futures superplastic alloys is set forth. The experimental characterization of the superplastic forming is achieved with free bulging of circular membranes of 12, 16, 24, 32 and 40 mm in diameter and with three different membrane thicknesses (0.4, 0.6, 0.8 mm). [Spanish] Se definen los pasos necesarios para el conformado superplastico de la aleacion Cd-17.4 Zn. Se comparan la presion atmosferica y el gas a presion como herramientas de conformado. Se determinan los valores optimos de la variables involucradas (temperatura, deformacion maxima e indice de sensibilidad) y se plantea una metodologia para la caracterizacion de futuras aleaciones superplasticas. El conformado superplastico se caracteriza experimentalmente mediante el inflado libre de membranas circulares de 12, 16, 24, 32 y 40 mm de diametro y tres diferentes espesores (0.4, 0.6 y 0.8 mm). Se muestra la estructura perlitica (enfuiada al aive Cd-17.4Zn) y la estructura grano fino. Se muestra la profundidad de deformacion en tres espesores (0.4, 0.6, 0.8 mm) a P=200 Kpa y T = 200 y a T = 230.

  6. Designing new biocompatible glass-forming Ti75-x Zr10 Nbx Si15 (x = 0, 15) alloys: corrosion, passivity, and apatite formation.

    Science.gov (United States)

    Abdi, Somayeh; Oswald, Steffen; Gostin, Petre Flaviu; Helth, Arne; Sort, Jordi; Baró, Maria Dolors; Calin, Mariana; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2016-01-01

    Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75 Zr10 Si15 and Ti60 Zr10 Nb15 Si15 alloys (free of cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type nanocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37°C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities icorr  corrosion properties, the Nb-containing nearly single-phase glassy alloy can compete with the β-type Ti-40Nb alloy. SBF tests confirmed the ability for formation of hydroxyapatite on the melt-spun alloy surfaces. All these properties recommend the new glass-forming alloys for application as wear- and corrosion-resistant coating materials for implants.

  7. Martensitic transformation in nanostructured TiNi shape memory alloy formed via severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, K. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan)]. E-mail: tsuchiya@pse.tut.ac.jp; Inuzuka, M. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Tomus, D. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Hosokawa, A. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Nakayama, H. [Department of Mechanical Engineering, University of Washington (United States); Morii, K. [Research and Development Laboratory, Daido Steel, Co., Ltd. (Japan); Todaka, Y. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan); Umemoto, M. [Department of Production Systems Engineering, Toyohashi University of Technology (Japan)

    2006-11-25

    Martensitic transformation and mechanical behavior was investigated on TiNi shape memory alloy subjected to severe plastic deformation by cold rolling. Transmission electron microscopy revealed the sample to be a mixture of nanocrystalline and amorphous material after 40% cold rolling. Diffrential scaning calorimetry measurements and X-ray diffractometry suggested that the martensitic transformation was suppressed when the thickness reduction was over 25%. The pseudoelastic stress-strain curves of nanocrystalline/amorphous TiNi are characterized by the absence of a stress-plateau and by small hysteresis.

  8. Numerical modelling of microstructure forming process for Al-Al3Fe eutectic alloy

    Institute of Scientific and Technical Information of China (English)

    李荣德; 周振平

    2003-01-01

    A self-adjusting model was presented on the basis of the effect of temperature gradient on eutectic growth and a curved solid/liquid interface. Finite differential method was adopted to solve the model. The average lamellar spacing of the Al-Al3Fe eutectic alloy and the content fields ahead of the solidifying interface under different growth rates were calculated. Directional solidification experiments were carried out in order to prove the modification of the modeling. The experimental results are in relatively good agreement with the calculations.

  9. Gibbs Free Energy and Activation Energy of ZrTiAlNiCuSn Bulk Glass Forming Alloys

    Institute of Scientific and Technical Information of China (English)

    Jianfei SUN; Jun SHEN; Zhenye ZHU; Gang WANG; Dawei XING; Yulai GAO; Bide ZHOU

    2004-01-01

    The Gibbs free energy differences between the supercooled liquid and the crystalline mixture for the (Zr52.5Ti5Al10- Ni14.6Cu17.9)(100-x)/100Snx ·(x=0, 1, 2, 3, 4 and 5) glass forming alloys are estimated by introducing the equation proposed by Thompson, Spaepen and Turnbull. It can be seen that the Gibbs free energy differences decrease first as the increases of Sn addition smaller than 3, then followed by a decrease due to the successive addition of Sn larger than 3, indicating that the thermal stabilities of these glass forming alloys increase first and then followed by a decrease owing to the excessive addition of Sn. Furthermore, the activation energy of Zr52.5Ti5Al10Ni14.6Cu17.9 and (Zr5 2.5Ti5 Al10 Ni14.6 Cu 17.9)0.97Sn3 was evaluated by Kissinger equation. It is noted that the Sn addition increases the activation energies for glass transition and crystallization, implying that the higher thermal stability can be obtained by appropriate addition of Sn.

  10. Modeling of precipitate-free zone formed upon homogenization in a multi-component alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gandin, Ch.-A. [CEMEF UMR CNRS-ENSMP 7635, Ecole des Mines, BP207, 06904 Sophia Antipolis (France) and LSG2M UMR CNRS-INPL-UHP 7584, Ecole des Mines, Parc de Saurupt, 54042 Nancy (France)]. E-mail: charles-andre.gandin@ensmp.fr; Jacot, A. [LSMX, MX-G, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); CALCOM ESI SA, PSE, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)

    2007-04-15

    A comprehensive model is presented for the simulation of microstructure evolution during industrial solidification and homogenization processing of aluminum alloys. The model combines on the one hand microsegregation due to long-range diffusion during solidification and subsequent heat treatment with, on the other hand, precipitation in the primary Al phase. The thermodynamic data are directly obtained from a CALPHAD (CALculation of PHAse Diagrams) approach to thermodynamic equilibrium in multicomponent systems. The model is applied to the prediction of structure and segregation evolutions in a 3003 aluminum alloy for typical industrial solidification and homogenization sequences. It is shown that: (i) accounting for the nucleation undercooling of the eutectic/peritectic structures solidifying from the melt is essential to retrieval of the measured volume fractions of intergranular precipitates; (ii) calculations of intragranular precipitation are generally not applicable if long-range diffusion is neglected; (iii) the precipitate-free zone can be quantitatively predicted only based on the coupling between intergranular and intragranular precipitation calculations.

  11. Microstructure and property development in spray formed and extruded Al-Mg-Li-Zr alloys for aerospace and autosport applications

    Energy Technology Data Exchange (ETDEWEB)

    Mi, J.; Grant, P.S. [Department of Materials, Oxford University (United Kingdom); Nilsen, K.E.; Liotti, E. [BOAL UK Ltd. Loughborough (United Kingdom); Hogg, S.C.

    2010-07-15

    Low density Al-4Mg-1.3Li-0.4Zr and Al-6Mg-1.6Li-0.4Zr alloys were spray formed and the billets extruded under a range of conditions. The alloy compositions were selected to provide an attractive balance of tensile strength and elongation, without relying on complex post-processing and heat treatments - and are therefore suitable for complex cross section extrusions and free from quench distortion. The as-spray formed microstructures showed fine homogeneous, equiaxed grains with an average size of 10-15 {mu}m. Firstly, a laboratory scale extrusion was carried out to extrude 30 mm diameter billets into 7.5 mm diameter cross-section and to investigate the effects of temperature and ram speeds on microstructural development. The microstructure after extrusion at 400 C was partially dynamically recrystallised with a {proportional_to}0.5 area fraction of {proportional_to}1 {mu}m grains and the remainder were unrecrystallised elongated grains. Electron backscatter diffraction showed a mixed <111> + <100> double fibre texture. After peak age hardening at 150 C for 96 h, the Al-6Mg-1.6Li-0.4Zr alloy showed a 0.2% proof strength of 495 MPa, a tensile strength of 553 MPa and elongation to failure of 8.5%; Al-4Mg-1.3Li-0.4Zr showed a 0.2% proof strength of 392 MPa, a tensile strength of 476 MPa and an elongation of 10%. Subsequently, large-scale complex cross-section were extruded at {proportional_to}400 C. Due to the complexity of the cross-sections and the non-axisymetric deformation, the fibre texture was distorted to FCC rolled Copper and Brass orientations. After a dual-step age hardening treatment of 130 C for 8h followed by 160 C for 8h, the proof strength, ultimate strength and elongations were 340 MPa, 470 MPa and 16% respectively. The combination of relatively simple process steps, high strength and ductility/formability, and low distortion in complex sections demonstrated the strong potential for these low density alloys in aerospace and autosport applications

  12. ANALYSIS OF RUBBER FORMING PROCESS OF FIRE BARRIER FROM TITANIUM CP2 ALLOY FOR AW 139 HELICOPTER

    Directory of Open Access Journals (Sweden)

    Mariusz Krakowski

    2015-05-01

    Full Text Available This paper presents conditions of forming products from titanium sheets by means of rubber stamping method. After introducing the issues connected with these elements manufacturing for aviation industry, considering standards and legal regulations, technological problems occurring during forming deep stiffening ribs. The results in the characteristic curvatures and distortion in the final products were generated in the process heterogeneous internal stress state. The Authors aimed at explaining and presenting of solutions limiting occurrence of chosen shape faults, which disqualify these products application in aviation industry. The proposed solutions significantly reduced the incidence of these unfavorable phenomena. The modified method of rubber stamping of firewall from titanium alloy CP-2 sheet was successfully implemented in manufacturing conditions of PZL Swidnik.

  13. Cell interaction with modified nanotubes formed on titanium alloy Ti-6Al-4V.

    Science.gov (United States)

    Moravec, Hynek; Vandrovcova, Marta; Chotova, Katerina; Fojt, Jaroslav; Pruchova, Eva; Joska, Ludek; Bacakova, Lucie

    2016-08-01

    Nanotubes with diameters ranging from 40 to 60nm were prepared by electrochemical oxidation of the Ti-6Al-4V alloy in electrolyte containing ammonium sulphate and ammonium fluoride. The nanotubes were further modified with calcium and phosphate ions or were heat treated. Polished Ti-6Al-4V alloy served as a reference sample. The spreading of human osteoblast-like cells was similar on all nanotube samples but lower than on polished samples. The number of initially adhered cells was higher on non-modified nanotubes, but the final cell number was the highest on Ca-enriched nanotubes and the lowest on heat-treated nanotubes. However, these differences were relatively small and less pronounced than the differences in the concentration of specific molecular markers of cell adhesion and differentiation, estimated by their intensity of immunofluorescence staining. The concentration of vinculin, i.e. a protein of focal adhesion plaques, was the lowest on nanotubes modified with calcium. Collagen I, an early marker of osteogenic cell differentiation, was also the lowest on samples modified with calcium and was highest on polished samples. Alkaline phosphatase, a middle marker of osteogenic differentiation, was observed in lowest concentration on nanotubes modified with phosphorus and the highest on heat-treated samples. Osteocalcin concentrations, a late marker of osteogenic cell differentiation, were similar on all tested samples, although they tended to be the highest on heat-treated samples. Thus, osteogenic differentiation can be modulated by various additional treatments of nanotube coatings on Ti-6Al-4V implants.

  14. Effect of P addition on glass forming ability and soft magnetic properties of melt-spun FeSiBCuC alloy ribbons

    Science.gov (United States)

    Xu, J.; Yang, Y. Z.; Li, W.; Chen, X. C.; Xie, Z. W.

    2016-11-01

    The dependency of phosphorous content on the glass forming ability, thermal stability and soft magnetic properties of Fe83.4Si2B14-xPxCu0.5C0.1 (x=0,1,2,3,4) alloys was investigated. The experimental results showed that the substitution of B by P increased the glass forming ability in this alloy system. The Fe83.4Si2B10P4Cu0.5C0.1 alloy shows a fully amorphous character. Thermal stability of melt-spun ribbons increases and temperature interval between the first and second crystallization peaks enlarges with the increase of P content. And the saturation magnetic flux density (Bs) shows a slight increase with the increase of P content. The Fe83.4Si2B11P3Cu0.5C0.1 nanocrystalline alloy exhibits a high Bs about 200.6 emu/g. The Bs of fully amorphous alloy Fe83.4Si2B10P4Cu0.5C0.1 drops dramatically to 172.1 emu/g, which is lower than that of other nanocrystallines. Low material cost and excellent soft magnetic properties make the FeSiBPCuC alloys promise soft magnetic materials for industrial applications.

  15. Effect of Pre-aging on Stress Corrosion Cracking of Spray-formed 7075 Alloy in Retrogression and Re-aging

    Science.gov (United States)

    Su, Rui-ming; Qu, Ying-dong; You, Jun-hua; de Li, Rong-

    2015-11-01

    The effects of pre-aging in retrogression and re-aging (RRA) treatment on microstructure, mechanical properties, and stress corrosion cracking (SCC) behavior of spray-formed 7075 aluminum alloy were investigated by tensile test, slow strain rate test, and transmission electron microscope. The results show that the under aging (120 °C for 16 h) as the pre-aging in RRA treatment can vastly improve the mechanical properties and the SCC resistance of the alloy, compared with early aging (120 °C for 8 h), peak aging (120 °C for 24 h), and over aging (120 °C for 32 h) treatments, the ultimate tensile strength of the alloy is 782 MPa, which is higher than that for peak aging or conventional RRA treatment; and the SCC resistance of the alloy is also excellent after RRA with under aging as pre-aging.

  16. Effects of Mo additions on the glass-forming ability and magnetic properties of bulk amorphous Fe-C-Si-B-P-Mo alloys

    Institute of Scientific and Technical Information of China (English)

    YI; Seonghoon

    2010-01-01

    Glass formation, mechanical and magnetic properties of the Fe76-xC7.0Si3.3B5.0P8.7Mox (x=0, 1 at.%, 3 at.% and 5 at.%) alloys prepared using an industrial Fe-P master alloy have been studied. With the substitution of Mo for Fe, glass-forming ability (GFA) was significantly enhanced and fully amorphous rods with a diameter of up to 5 mm were produced in the alloy with 3% Mo. The Mo-containing amorphous alloys also exhibited high fracture strength of 3635–3881 MPa and excellent magnetic properties including a high saturation magnetization of 1.10–1.41 T, a high Curie temperature and a low coercive force. The unique combination of high GFA, high fracture strength and excellent magnetic properties make the newly developed bulk metallic glasses viable for practical engineering applications.

  17. Incremental forming of free surface with magnesium alloy AZ31 sheet at warm temperatures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The formability of AZ31 sheet begins to increase drastically at 150 ℃. The incremental forming technique was thus applied to AZ31 sheet at 150 ℃ to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications. A surface scanning technique was used followed by the tool path generation to incrementally form an egg surface. After thorough examination of various tool paths, the surface was most successfully produced by forming an intermediate shape followed by a series of tool paths. Flexible scale stickers were devised to improve the accuracy in the measurement of grid deformation.

  18. Examination of the Oxidation Protection of Zinc Coatings Formed on Copper Alloys and Steel Substrates

    Science.gov (United States)

    Papazoglou, M.; Chaliampalias, D.; Vourlias, G.; Pavlidou, E.; Stergioudis, G.; Skolianos, S.

    2010-01-01

    The exposure of metallic components at aggressive high temperature environments, usually limit their usage at similar application because they suffer from severe oxidation attack. Copper alloys are used in a wide range of high-quality indoor and outdoor applications, statue parts, art hardware, high strength and high thermal conductivity applications. On the other hand, steel is commonly used as mechanical part of industrial set outs or in the construction sector due to its high mechanical properties. The aim of the present work is the examination of the oxidation resistance of pack cementation zinc coatings deposited on copper, leaded brass and steel substrates at elevated temperature conditions. Furthermore, an effort made to make a long-term evaluation of the coated samples durability. The oxidation results showed that bare substrates appear to have undergone severe damage comparing with the coated ones. Furthermore, the mass gain of the uncoated samples was higher than this of the zinc covered ones. Particularly zinc coated brass was found to be more resistant to oxidation conditions in which it was exposed as it has the lower mass gain as compared to the bare substrates and zinc coated copper. Zinc coated steel was also proved to be more resistive than the uncoated steel.

  19. Effects of Microalloying on Glass Forming Ability and Thermodynamic Fragility of Cu-Pr-Based Amorphous Alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of microalloying of Ti and B on the glass formation of Cu60Pr30Ni10Al10-2xTixBx(x=0, 0.05%(atom fraction)) amorphous alloys was investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). XRD analysis showed that microalloying with 0.05% Ti and 0.05% B improved the glass forming ability (GFA). The smaller difference in the Gibbs free energy between the liquid and crystalline states at the glass transition temperature (ΔGl-x (Tg)) and the smaller thermodynamic fragility index (ΔSf/Tm, where ΔSf is the entropy of fusion, and Tm is the melting temperature) after microalloying correlated with the higher GFA.

  20. Structural State of a Weld Formed in Aluminum Alloy by Friction Stir Welding and Treated by Ultrasound

    Science.gov (United States)

    Klimenov, V. A.; Abzaev, Yu. A.; Potekaev, A. I.; Vlasov, V. A.; Klopotov, A. A.; Zaitsev, K. V.; Chumaevskii, A. V.; Porobova, S. A.; Grinkevich, L. S.; Tazin, I. D.; Tazin, D. I.

    2016-11-01

    The experimental data on structural state of an aluminum alloy, AlMg6, in the weld zone formed by friction stir welding are analyzed in order to evaluate the effect of its subsequent ultrasonic treatment. It is found that the crystal lattice transits into a low-stability state as a result of combined heat-induced and severe shear deformation. This transition is accompanied by considerable structural-phase changes that are manifested as an increased lattice parameter of the solid solution. This increase is caused by both high values of internal stresses and increased concentration of Mg atoms in the solid solution due to essential dissolution of the β-Al2Mg3 particles with the content of manganese higher than that in the matrix. This is accompanied by high-intensity diffusion and relaxation processes due to the low-stability state of crystal lattice (inhomogeneous stresses) in the weld zone.

  1. Studies of Nucleation, Growth, Specific Heat, and Viscosity of Undercooled Melts of Quasicrystals and Polytetrahedral-Phase-Forming Alloys

    Science.gov (United States)

    Kelton, K. F.; Croat, T. K.; Gangopadhyay, A.; Holland-Moritz, D.; Hyers, Robert W.; Rathz, Thomas J.; Robinson, Michael B.; Rogers, Jan R.

    2001-01-01

    Undercooling experiments and thermal physical property measurements of metallic alloys on the International Space Station (ISS) are planned. This recently-funded research focuses on fundamental issues of the formation and structure of highly-ordered non-crystallographic phases (quasicrystals) and related crystal phases (crystal approximants), and the connections between the atomic structures of these phases and those of liquids and glasses. It extends studies made previously by us of the composition dependence of crystal nucleation processes in silicate and metallic glasses, to the case of nucleation from the liquid phase. Motivating results from rf-levitation and drop-tube measurements of the undercooling of Ti/Zr-based liquids that form quasicrystals and crystal approximants are discussed. Preliminary measurements by electrostatic levitation (ESL) are presented.

  2. Crystalline Precipitate in a Bulk Glass Forming Zr-Based Alloy and Its Effect on Mechanical Properties

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Cylindrical and sheet samples of bulk metallic glass with a nominal composition of Zr52.5Ni14.6Al10Cu17.9Ti5 (at. pct) were prepared by melt injection casting. The crystalline precipitates formed during the casting were studied by metallographic observations and selected-area electron diffractions. The effect of crystalline precipitates on the mechanical properties were investigated by tensile and compressive tests at room temperature. Oxygen contents and the sample sizes (or cooling rates) strongly affect the formation of the crystalline precipitates. Overheating the alloy melt up to 200 K above its melting temperature can effectively prevent the formation of the crystalline precipitates to get fully glass samples with diameters up to 2 mm for cylinders and thickness up to 1 mm for sheets even the oxygen content is as higher as 0.08 wt pct.With increasing the sample sizes, the crystalline precipitates increase in volume fraction and size. The formation of the precipitates experienced two stages, i.e., initially nucleation and isotropic growth, and then anisotropic growth, finally forming faceted morphologies. Fully glassy Zr52.5Ni14.6Al10Cu17.9Ti5 alloy exhibits excellent tensile and compressive properties at room temperature. The presence of crystalline precipitates significantly decreases the tensile and compressive properties. With increasing the crystalline precipitates, the area of vein patterns on the fracture surface decreases, but the fracture steps increase, and the fracture mode changes from ductile to brittle resulting from the larger stress concentration caused by the larger sizes and faceted shapes of the crystalline precipitates.

  3. Development of fine-grain size titanium 6Al–4V alloy sheet material for low temperature superplastic forming

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tuoyang [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan (China); Liu, Yong, E-mail: yonliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan (China); Sanders, Daniel G. [Boeing Research and Technology, Seattle, WA (United States); Liu, Bin; Zhang, Weidong; Zhou, Canxu [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan (China)

    2014-07-01

    Fine-grained titanium 6Al–4V alloy, which typically has a grain size of about 1–2 μm, can be made to superplastic form at around 800 °C with special processing. The normal temperature for superplastic forming (SPF) with conventional titanium 6Al–4V sheet material is 900 °C. The lower temperature performance is of interest to the Boeing Company because it can be exploited to achieve significant cost savings in processing by reducing the high-temperature oxidation of the SPF dies, improving the heater rod life for the hot presses, increasing operator safety and replacing the chemical milling operation to remove alpha case contamination with a less intensive nitric hydrofluoric acid etchant (pickle). In this report, room temperature tensile tests and elevated temperature constant strain rate tensile tests of fine-grained Ti–6Al–4V sheets provided by the Baoti Company of Xi'an, China, were conducted according to the test method standards of ASTM-E8 and ASTM-E2448. The relationships among the processing parameters, microstructure and superplastic behavior have been analyzed. The results show that two of the samples produced met the Boeing minimum requirements for low-temperature superplasticity. The successful material was heat-treated at 800 °C subsequent to hot rolling above the beta transus temperature, T{sub β}-(150–250 °C). It was found that the sheet metal microstructure has a significant influence on superplastic formability of the Ti–6Al–4V alloy. Specifically, fine grains, a narrow grain size distribution, low grain aspect ratio and moderate β phase volume fraction can contribute to higher superplastic elongations.

  4. Corrosion behaviour of gas turbine alloys under high velocity burnt fuels; Korrosionsverhalten von Gasturbinenwerkstoffen unter stroemenden Heissgasbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Haubold, T.I.; Brill, U. [Krupp VDM GmbH, Altena (Germany); Abel, H.J. [Fachhochschule Dortmund (Germany). Fachbereich 5/Maschinenbau, Laborgruppe Werkstofftechnik; Klauke, P. [Fachhochschule Gelsenkirchen (Germany). Fachbereich Chemie und Materialtechnik

    2001-04-01

    The aim of alloy development in the field of nickel based superalloys for flying and land based gas turbines is to enhance significantly the mechanical properties at high temperatures thus leading to a higher temperature capability. The higher temperature capability of the structural elements of gas turbines results in an increased efficiency, a lowered fuel consumption and less emissions. To achieve an increased high temperature capability, however, surface degradation of the material must be adjusted adequately, hence corrosion resistance has to be improved. Additional to the isothermal and cyclic oxidation tests which are performed in stagnant air the oxidation behaviour of alloy 2100 GT and alloy C-263 was investigated by means of burner-rig-experiments under high velocity burnt fuels. In the burner rig test facility the sample is exposed to a hot gas stream of burned natural gas with gas velocities in the range of 60 m/s to 150 m/s. The metal temperature of the sample can be adjusted in the range of 900 C to 1200 C. In the tests described in this paper the gas velocities were chosen to be 60 m/s, 100 m/s and 140 m/s. The test duration was 1 h and 10 h. The test temperature was kept constant at 1000 C. After 1 h of testing both alloys showed mass gain which was significantly higher for alloy C-263. After 10 h of testing the mass loss of alloy C-263 was enhanced with increasing gas velocity. Alloy 2100 GT showed only at the highest gas velocity a mass loss. The examinations by means of SEM and light-optical microscopy of the oxide scale and of the microstructure showed that alloy 2100 GT has a dense adherent alumina scale and suffers no internal oxidation even under burner-rig-test conditions. Alloy C-263 forms a mixed chromia and Cr-Ti-mixed oxide scale. The chromia is evaporated with increasing gas velocity, leaving (Cr-Ti)O{sub 2}-needles on the surface. In the isothermal and cyclic oxidation tests alloy 2100 GT shows an excellent oxidation behaviour up to

  5. Dry metal forming of high alloy steel using laser generated aluminum bronze tools

    Directory of Open Access Journals (Sweden)

    Freiße Hannes

    2015-01-01

    Full Text Available Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the tool and sheet material. The potential to generate tailored tribological systems for dry metal forming could be shown within the investigations by using different material combinations and by applying different laser cladding process parameters. Furthermore, the feasibility of additive manufacturing of a deep drawing tool was demonstrated. The tool was successfully applied to form circular cups in a dry metal forming process.

  6. Forming Limits of Weld Metal in Aluminum Alloys and Advanced High-Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Elizabeth V.; Smith, Mark T.; Grant, Glenn J.; Davies, Richard W.

    2010-10-25

    This work characterizes the mechanical properties of DP600 laser welded TWBs (1 mm-1.5 mm) near and in the weld, as well as their limits of formability. The approach uses simple uniaxial experiments to measure the variability in the forming limits of the weld region, and uses a theoretical forming limit diagram calculation to establish a probabilistic distribution of weld region imperfection using an M-K method approach

  7. Forming limits under multi-index constraints in NC bending of aluminum alloy thin-walled tubes with large diameters

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With increasing diameters of aluminum alloy thin-walled tubes (AATTs), the tube forming limits, i.e. the minimum bending factors, and their predictions under multi-index constraints including wrinkling, thinning and flattening have been being a key problem to be urgently solved for improving tube forming potential in numerical control (NC) bending processes of AATTs with large diameters. Thus in this paper, a search algorithm of the forming limits is put forward based on a 3D elastic-plastic finite element (FE) model and a wrinkling energy prediction model for the bending processes under axial compression loading (ACL) or not. This algorithm enables to be considered the effects of process parameter combinations including die, friction parameters on the multi-indices. Based on this algorithm, the forming limits of the different size tubes are obtained, and the roles of the process parameter combinations in enabling the limit bending processes are also revealed. The followings are found: the first, within the appropriate ranges of friction and clearances between the different dies and the tubes enabling the bending processes with smaller bending factors, the ACL enables the tube limit bending processes after a decrease of the mandrel ball thickness and diameters; then, without considering the effects of the tube geometry sizes on the tube constitutive equations, the forming limits will be decided by the limit thinning values for the tubes with diameters smaller than 80 mm, while the wrinkling for the tubes with diameters no less than 80 mm. The forming limits obtained from this algorithm are smaller than the analytical results, and reduced by 57.39%; the last, the roles of the process parameter combinations in enabling the limit bending processes are verified by experimental results.

  8. Influence of coupling with calculation of phase diagrams on microsegregation forming simulation of Al-4.5%Cu alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-gang; CHEN Guang; SUN Guo-xiong

    2006-01-01

    The effect of coupling with calculation of phase diagrams on microsegregation forming simulation was investigated. The traditional simplified phase diagram and calculated phase diagram were introduced into the numerical models respectively and simulation on microsegregation forming of the Al-4.5%Cu alloy ingot was also presented. The simulation results were both compared with the experiment results. The results show that the calculated sencondary arm spacing with these two kinds of phase diagram are almost the same because relationship between the coarsening model and the information of phase diagram is not close. The calculated eutectic phase volume fractions of different locations in the ingot coupled with different phase diagrams are discrepant. The calculated volume fractions are consistent with the experiment results when calculated phase diagram couples, but are far from the experiment results and obviously inacceptable when traditional simplified phase diagram couples. So, coupling with accurate calculated phase diagrams is very significant for microsegregation forming simulation since much information of the phase diagram is used in the models and it can improve the precision of simulation results.

  9. Fatigue property of a bioabsorbable magnesium alloy with a hydroxyapatite coating formed by a chemical solution deposition.

    Science.gov (United States)

    Hiromoto, Sachiko; Tomozawa, Masanari; Maruyama, Norio

    2013-09-01

    A hydroxyapatite (HAp) coating was directly formed on an extruded AZ31 magnesium alloy by a single-step chemical solution deposition. The HAp coating consists of an outer porous HAp layer, an inner continuous HAp layer, and a thin intermediate MgO layer, and the inner HAp and MgO layers are composed of nanocrystals. Tensile and fatigue tests were performed on the HAp-coated AZ31 in air. The HAp coating microscopically showed neither crack nor detachment at 5% static elongation (1.5% residual strain). With further elongation under tensile stress, cracks were formed perpendicularly to the tensile direction, and fragments of the coating detached with a fracture inside the inner continuous HAp layer. The fatigue strengths at 10(7) cycles (fatigue limit) of HAp-coated and mechanically polished AZ31 were ca. 80 MPa and ca. 90 MPa, respectively. The slight decrease in the fatigue limit with the HAp coating is attributed to small pits with a depth of ca. 10 μm formed on the substrate during the HAp-coating treatment. The HAp coating remained on the specimen without cracks after 10(7) cycles at the fatigue limit, which provides ca. 3% cyclic elongation.

  10. Liquid -to-glass transition in bulk glass-forming Cu55-xZr45Agx alloys using molecular dynamic simulations

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available We report results from molecular dynamics (MD studies concerning the microscopic structure of the ternary, bulk metallic glass-forming Cu55-x Zr45Agx (x=0,10,20 alloys using tight-binding potentials. Understanding of the nature of Glass Forming Ability (GFA of studied alloys, GFA parameters, glass transition temperature (T-g, melting temperature (T-m, reduced glass transition temperature (T-g/T-m, the supercooled liquid region and other parameters were simulated and compared with experiments. The computed pair distribution functions reproduce well experimental x-ray data of Inoue and co-workers. Structure analysis of the Cu-Zr-Ag alloy based on MD simulation will be also presented

  11. Containerless processing of hypermonotectic and glass forming alloys using the Marshall Space Flight Center 100 meter drop tube facility

    Science.gov (United States)

    Andrews, J. B.

    1986-01-01

    Two separate projects were carried out to study alloys whose solidification structures can be strongly influenced by the presence of a container during melting and solidifications. One project involved containerless solidification of hypermonotectic Au35Rh65 alloys. This alloy exhibits liquid immiscibility over a temperature range. It has been suggested that containerless melting might be one solution to the problem of sedimentation in the dispersions of immiscible liquid phases. However, surface tension driven flows could also lead to accumulation of the minority liquid phase at the external surface of a containerlessly melted alloy. The research underway is a first step in determining the influence of containerless, microgravity processing on immiscible alloys. Nickel-niobium alloys were studied using the drop tube facility. One alloy in this system, a Ni60Nb40 alloy, is a good candidate for the formation of a bulk metallic glass. Amorphous alloys of this composition were produced using thin film and mechanical alloying techniques. However, theory indicates that if heterogeneous nucleation can be avoided, it should be possible to produce an amorphous structure in this system using a moderate cooling rate from the melt. The containerless melting and solidification capabilities of the drop tube faciltiy provide ideal conditions for a study of this type. To date, several Ni60Nb40 samples have been levitated, melted and cooled during 4.6 seconds of free fall in the 100 meter drop tube. Structures obtained are discussed.

  12. Finite Element Simulation in Superplastic forming of Friction Stir Welded Aluminium Alloy 6061-T6

    Directory of Open Access Journals (Sweden)

    P Ganesh

    2011-09-01

    Full Text Available Superplasticity in materials is the ability of materials to achieve large elongation only under specific conditions of temperature and strain rate. Superplastic Forming (SPF is an important industrial process that has found application in sheet metal forming in the aerospace and automotive industries. Friction Stir Welding (FSW is a solid state joining process that can alter the grain structure of the parent material. FSW process is an effective tool to refine the grain structure of the sheet metal and enhance their Superplasticity. Friction Stir Welding was used to join Superplastic AA 6061-T6 sheets. The Finite Element Simulation was performed for the Superplastic Forming of the Friction Stir Welded joints to evaluate the thinning and formability of AA 6061-T6 for hemispherical shape. The commercially available Finite Element Software ABAQUS was used to execute these simulations.

  13. Corrosion behaviour of Al{sub 86.0}Co{sub 7.6}Ce{sub 6.4} glass forming alloy with different microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.L., E-mail: lichunling@upc.edu.cn [Department of Materials Physics and Chemistry, College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Wang, P.; Sun, S.Q. [Department of Materials Physics and Chemistry, College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Voisey, K.T.; McCartney, D.G. [Materials, Mechanics and Structures Research Division, Faculty of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2016-10-30

    Highlights: • Corrosion behaviour of Al-Co-Ce glass forming alloys is microstructure dependent. • Coarse-grain and microstructure refined crystalline alloys were locally corroded. • The superior corrosion resistance of EBSM treated alloy was limited by cracks. • Crack-free amorphous layer generated by LSM-EBSM showed uniform and slight corrosion. - Abstract: It has been extensively reported that Al-TM-RE amorphous alloy has excellent mechanical properties and corrosion resistance. In this paper, the corrosion behaviour of an Al{sub 86.0}Co{sub 7.6}Ce{sub 6.4} glass forming alloy with different microstructures is investigated through electrochemical experiments and microscopy. Results show the effect of microstructure. Laser and electron beam surface melting processes produce rapidly solidified microstructures with different extents of passivation compared to the as-cast alloy. An amorphous surface layer produced by these surface treatments had superior corrosion resistance compared with the crystalline alloy. As-cast and laser treated Al{sub 86.0}Co{sub 7.6}Ce{sub 6.4} suffered localised corrosion in the Al/Al{sub 11}Ce{sub 3} eutectic region whereas the amorphous material exhibited uniform corrosion. Compared with the electrochemical behaviour of AA2024 and Alclad 2024, the fully amorphous layer prepared by combined laser-electron beam treatment exhibited advantages such as the more negative corrosion potential, the higher pitting potential and the uniform corrosion mechanism, which indicates that this material is a potential anode candidate in the protection of AA2024.

  14. Laser engineered surfaces from glass forming alloy powder precursors : Microstructure and wear

    NARCIS (Netherlands)

    Matthews, D. T. A.; Ocelik, V.; Branagan, D.; de Hosson, J. Th. M.

    2009-01-01

    Fe-based metallic glass forming powders have been deposited on mild steel substrates using high power laser cladding. Coatings microstructures have been analysed by scanning- and transmission-electron microscopy and at varying substrate dilutions, have been found to comprise a 100 to 500 nm interden

  15. Raising the Reliability of Forming Rolls by Alloying Their Core with Copper

    Science.gov (United States)

    Zhizhkina, N. A.

    2016-11-01

    The mechanical properties and the structure of forming rolls from cast irons of different compositions are studied. A novel iron including a copper additive that lowers its chilling and raises the homogeneity of the structure is suggested for the roll cores. The use of such iron should raise the reliability of the rolls in operation.

  16. Antibacterial and bioactive calcium titanate layers formed on Ti metal and its alloys.

    Science.gov (United States)

    Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi

    2014-07-01

    An antibacterial and bioactive titanium (Ti)-based material was developed for use as a bone substitute under load-bearing conditions. As previously reported, Ti metal was successively subjected to NaOH, CaCl2, heat, and water treatments to form a calcium-deficient calcium titanate layer on its surface. When placed in a simulated body fluid (SBF), this bioactive Ti formed an apatite layer on its surface and tightly bonded to bones in the body. To address concerns regarding deep infection during orthopedic surgery, Ag(+) ions were incorporated on the surface of this bioactive Ti metal to impart antibacterial properties. Ti metal was first soaked in a 5 M NaOH solution to form a 1 μm-thick sodium hydrogen titanate layer on the surface and then in a 100 mM CaCl2 solution to form a calcium hydrogen titanate layer via replacement of the Na(+) ions with Ca(2+) ions. The Ti material was subsequently heated at 600 °C for 1 h to transform the calcium hydrogen titanate into calcium titanate. This heat-treated titanium metal was then soaked in 0.01-10 mM AgNO3 solutions at 80 °C for 24 h. As a result, 0.1-0.82 at.% Ag(+) ions and a small amount of H3O(+) ions were incorporated into the surface calcium titanate layers. The resultant products formed apatite on their surface in an SBF, released 0.35-3.24 ppm Ag(+) ion into the fetal bovine serum within 24 h, and exhibited a strong antibacterial effect against Staphylococcus aureus. These results suggest that the present Ti metals should exhibit strong antibacterial properties in the living body in addition to tightly bonding to the surrounding bone through the apatite layer that forms on their surfaces in the body.

  17. Dry metal forming of high alloy steel using laser generated aluminum bronze tools

    OpenAIRE

    Freiße Hannes; Köhler Henry; Seefeld Thomas; Vollertsen Frank

    2015-01-01

    Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the too...

  18. Vanadium Alloyed PVD CrAlN Coatings for Friction Reduction in Metal Forming Applications

    Directory of Open Access Journals (Sweden)

    K. Bobzin

    2012-06-01

    Full Text Available Hard coatings deposited on forming tools are used to improve the forming process and to increase tool life. The decrease of tool wear and reduction of friction are the main motivations for the development of self-lubricating coatings for forming applications at elevated temperatures. In the present study (Cr,Al,VN (Physical Vapour Deposition coatings with 5, 11 and 20 at % vanadium were deposited via a combination of HPPMS (High Power Pulse Magnetron Sputtering technology and direct current (DC Magnetron Sputter Ion Plating (MSIP PVD. The hardness and Young’s Modulus of the coatings were investigated by nanoidentation. Furthermore, high temperature Pin-on-Disk (PoD tribometer measurements against Ck15 (AISI 1015 were realized at different temperatures and compared with a (Cr,AlN reference hard coating. The samples were analyzed by means of SEM (Scanning Electron Microscopy and XRD (X-Ray Diffraction measurements after Pin-on-Disk (PoD tests. Moreover TEM (Transmission Electron Microscopy analyses were carried out after 4 h annealing at 800 °C in ambient air to investigate the diffusion of vanadium to the coating surface. The tribological results at 800 °C show no improvement of the friction coefficient for the pure (Cr,AlN coating and for the layer with 5 at % V. A time-dependent decrease of the friction coefficient was achieved for the coatings with 11 at % V (µ=0.4 and 20 at % V (µ=0.4 at 800 °C.

  19. Tool degradation during sheet metal forming of three stainless steel alloys

    DEFF Research Database (Denmark)

    Wadman, Boel; Nielsen, Peter Søe; Wiklund, Daniel

    2010-01-01

    To evaluate if changes in tool design and tool surface preparation are needed when low-Ni stainless steels are used instead of austenitic stainless steels, the effect on tool degradation in the form of galling was investigated with three different types of stainless steel. The resistance to tool...... degradation was analysed by the strip reduction test, simulating resistance to galling during ironing. It was shown that the surface condition of both the tools and the sheet metal was of importance to the galling resistance. Numerical simulations of the experimental tests were compared with the experimental...

  20. Glass forming range of the Ti-Fe-Si amorphous alloys: An effective materials-design approach coupling CALPHAD and topological instability criterion

    Science.gov (United States)

    Zhao, Guo-Hua; Mao, Huahai; Louzguine-Luzgin, Dmitri V.

    2016-11-01

    A method of composition design for metallic glasses was proposed by using the Calculation of Phase Diagrams (CALPHAD) with the assistance of the topological instability criterion. This methodology was demonstrated in the quick and effective searching of glass-forming regions for Ti-Fe-Si and Ti-Zr-Fe-Si alloys containing no biologically toxic elements, e.g., Ni and Cu. In addition, the Ti-Fe-Si system may promote the glass formation owing to the existence of a deep eutectic at the Ti-rich corner. A self-consistent thermodynamic database was constructed based on the CALPHAD approach. The liquidus projection, isothermal sections, and the enthalpy of mixing were calculated by using the database. On the basis of these calculations coupling with the topological instability "lambda λ criterion," the potential glass-forming alloy compositions in a narrow region were suggested for experimental validation. Thereafter, the isothermal sections of the Ti-Zr-Fe-Si quaternary system were calculated at certain contents of Zr. The designed alloys were prepared by arc-melting and followed by melt-spinning to the ribbon shape. The experimental verifications matched reasonably well with the theoretical calculations. This work offers new insights for predicting glass-forming alloys based on thermodynamic arguments; it shall be of benefit for the exploration of new metallic glasses.

  1. Investigation of the inner corrosion layer formed in pulse electrodeposition coating on Mg-Sr alloy and corresponding degradation behavior.

    Science.gov (United States)

    Shangguan, Yongming; Wan, Peng; Tan, Lili; Fan, Xinmin; Qin, Ling; Yang, Ke

    2016-11-01

    Magnesium-based metals are considered as promising biodegradable orthopedic implant materials due to their potentials of enhancing bone healing and reconstruction, and in vivo absorbable characteristic without second operation for removal. However, the rapid corrosion has limited their clinical applications. Ca-P coating by electrodeposition has been supposed to be effective to control the degradation rate and enhance the bioactivity. In this work, a brushite coating was fabricated on the Mg-Sr alloy by pulse electrodeposition (PED) to evaluate its efficacy for orthopedic application. Interestingly, an inner corrosion layer was observed between the PED coating and the alloy substrate. Meanwhile the results of in vitro immersion and electrochemical tests showed that the corrosion resistance of the coated alloy was undermined in comparison with the uncoated alloy. It was deduced that the existence of this corrosion layer was attributed to the worse corrosion performance of the alloy. The mechanism on formation of the inner corrosion layer and its influence on consequent degradation were analyzed. It can be concluded that the electrodeposition coating should be not suitable for those magnesium alloys with poor corrosion resistance such as the Mg-Sr alloy. More importantly, it should be noted that the process of coating formation combined with the nature of substrate alloy is important to evaluate the efficacy of coating for biodegradable Mg-based implants application.

  2. Preparation and Characterization of Amorphous Layer on Aluminum Alloy Formed by Plasma Electrolytic Deposition (PED)

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2004-01-01

    In this investigation, protective layers were formed on aluminum substrate by Plasma Electrolytic Deposition (PED) using sodium silicate solution. The relation between the thickness of the layer and process time were studied. XRD,SEM, EDS were used to study the layer's structure, composition and micrograph. The results show that the deposited layers are amorphous and contain mainly oxygen, silicon, and aluminum. The possible formation mechanism of amorphous [Al-Si-O] layer was proposed: During discharge periods, Al2O3 phase of the passive film and SiO32-near the substrate surface are sintered into xSiO2(1-x)Al2O3 and then transformed into amorphous [Al-Si-O] phase.

  3. Effect of the existing form of Cu element on the mechanical properties, bio-corrosion and antibacterial properties of Ti-Cu alloys for biomedical application.

    Science.gov (United States)

    Zhang, Erlin; Wang, Xiaoyan; Chen, Mian; Hou, Bing

    2016-12-01

    Ti-Cu alloys have exhibited strong antibacterial ability, but Ti-Cu alloys prepared by different processes showed different antibacterial ability. In order to reveal the controlling mechanism, Ti-Cu alloys with different existing forms of Cu element were prepared in this paper. The effects of the Cu existing form on the microstructure, mechanical, corrosion and antibacterial properties of Ti-Cu alloys have been systematically investigated. Results have shown that the as-cast Ti-Cu alloys showed a higher hardness and mechanical strength as well as a higher antibacterial rate (51-64%) but a relatively lower corrosion resistance than pure titanium. Treatment at 900°C/2h (T4) significantly increased the hardness and the strength, improved the corrosion resistance but had little effect on the antibacterial property. Treatment at 900°C/2h+400°C/12h (T6) increased further the hardness and the mechanical strength, improved the corrosion resistance and but also enhanced the antibacterial rate (>90%) significantly. It was demonstrated that the Cu element in solid solution state showed high strengthening ability but low antibacterial property while Cu element in Ti2Cu phase exhibited strong strengthening ability and strong antibacterial property. Ti2Cu phase played a key role in the antibacterial mechanism. The antibacterial ability of Ti-Cu alloy was strongly proportional to the Cu content and the surface area of Ti2Cu phase. High Cu content and fine Ti2Cu phase would contribute to a high strength and a strong antibacterial ability.

  4. Investigation of the structure/property relationship of spray-formed 7XXX series high-strength aluminum alloys and their metal matrix composites

    Science.gov (United States)

    Sharma-Judd, Malavika M.

    2000-12-01

    The purpose of this investigation was to identify the structure/property relationship of spray formed 7XXX series alloys. High solute, ultra-high strength 7XXX series aluminum alloys with solute contents close to equilibrium solid solubility limits of the Al-Zn-Mg-Cu system have been produced by rapid solidification using spray deposition. The process yields massive preforms directly from the liquid state. Various elements, including chromium, manganese, silver, zirconium and scandium, were incorporated to produce a variety of microstructures and mechanical properties. SiC particulate was added to these same alloy compositions to produce metal matrix composites (MMCs). The resulting extruded products in the T6 and T7 conditions were evaluated and compared. Under peak-aged conditions in the unreinforced materials, strengths in excess of 860 MPa were achieved, with one alloy exceeding 900 MPa. Apart from the elongation to failure, the mechanical properties of the composite materials were equal to or superior to those of their unreinforced counterparts. The superior strength properties of the spray formed alloys were attributed to two major substructures with different scale; nanometer sized eta ' metastable precipitates and slightly larger, but finely distributed dispersoids. The large volume fraction of plate-like eta' precipitates (average size 58A, ranging up to 73 A in diameter) were identified as having a hexagonal structure with lattice parameters a = 0.488 nm and c = 1.376. The remarkable strengthening is predominantly attributed to precipitation hardening. The enhanced mechanical properties of the MMC materials are attributed to the increased dislocation density, and thus, a higher concentration of structural particles compared to the unreinforced materials. Higher gas-to-metal ratios of 4.45, as opposed to lower gas-to-metal ratios of 1.95 produced a refined grain structure with an evenly distributed second phase. In both unreinforced and MMC materials

  5. CRADA NFE-08-01456 Evaluation of Alumina-Forming Austenitic Stainless Steel Alloys in Industrial Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Michael P [ORNL; Pint, Bruce A [ORNL; Unocic, Kinga A [ORNL; Yamamoto, Yukinori [ORNL; Kumar, Deepak [ORNL; Lipschutz, Mark D. [Solar Turbines, Inc.

    2011-09-01

    Oak Ridge National Laboratory (ORNL) and Solar Turbines Incorporated (Solar) participated in an in-kind cost share cooperative research and development agreement (CRADA) effort under the auspices of the Energy Efficiency and Renewable Energy (EERE) Technology Maturation Program to explore the feasibility for use of developmental ORNL alumina-forming austenitic (AFA) stainless steels as a material of construction for industrial gas turbine recuperator components. ORNL manufactured lab scale foil of three different AFA alloy compositions and delivered them to Solar for creep properties evaluation. One AFA composition was selected for a commercial trial foil batch. Both lab scale and the commercial trial scale foils were evaluated for oxidation and creep behavior. The AFA foil exhibited a promising combination of properties and is of interest for future scale up activities for turbine recuperators. Some issues were identified in the processing parameters used for the first trial commercial batch. This understanding will be used to guide process optimization of future AFA foil material production.

  6. Prediction of forming limit curve (FLC) for Al-Li alloy 2198-T3 sheet using different yield functions

    Institute of Scientific and Technical Information of China (English)

    Li Xiaoqiang; Song Nan; Guo Guiqiang; Sun Zhonggang

    2013-01-01

    The Forming Limit Curve (FLC) of the third generation aluminum-lithium (Al-Li) alloy 2198-T3 is measured by conducting a hemispherical dome test with specimens of different widths. The theoretical prediction of the FLC of 2198-T3 is based on the M-K theory utilizing respectively the von Mises, Hill’48, Hosford and Barlat 89 yield functions, and the different predicted curves due to different yield functions are compared with the experimentally measured FLC of 2198-T3. The results show that though there are differences among the four predicted curves, yet they all agree well with the experimentally measured curve. In the area near the planar strain state, the predicted curves and experimentally measured curve are very close. The predicted curve based on the Hosford yield function is more accurate under the tension-compression strain states described in the left part of the FLC, while the accuracy is better for the predicted curve based on Hill’48 yield function under the tension-tension strain states shown in the right part.

  7. A Combinatorial Approach to the Investigation of Metal Systems that Form Both Bulk Metallic Glasses and High Entropy Alloys

    Science.gov (United States)

    Welk, Brian A.; Gibson, Mark A.; Fraser, Hamish L.

    2016-03-01

    In this work, compositionally graded specimens were deposited using the laser engineered net-shaping (LENS™) additive manufacturing technique to study the glass-forming ability of two bulk metallic glass (BMG) and high entropy alloy (HEA) composite systems. The first graded specimen varied from Zr57Ti5Al10Cu20Ni8 (BMG) to CoCrFeNiCu0.5 (HEA) and the second graded specimen varied from TiZrCuNb (BMG) to (TiZrCuNb)65Ni35 (HEA). After deposition, laser surface melting experiments were performed parallel to the gradient to remelt and rapidly solidify the specimen. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to determine the morphology and composition variations in the as-deposited and laser surface melted phases. Selected area diffraction of the melt pool regions confirmed an almost fully amorphous region in the first gradient and an amorphous matrix/crystalline dendrite composite structure in the second gradient.

  8. Effects of lanthanum ion-implantation on microstructure of oxide film formed on Co-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    JIN Huiming; ZHOU Xiaowei; ZHANG Linnan

    2008-01-01

    Isothermal and cyclic oxidizing behavior of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1000℃ in the air by thermal-gravimetric analysis (TGA). Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine the morphology and structure of oxide film after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by La-doping and its influence on the formation of Cr2O3 film. Laser Raman spectrum was used to examine the stress changes within the oxide film. It was found that lanthanum implantation remarkably reduced isothermal oxidizing rate of Co-40Cr and improved anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement were mainly that the implanted lanthanum reduced the grain size and internal stress of Cr2O3 oxide and increased high temperature plasticity of the oxide film. Lanthanum mainly existed on the outer surface of Cr2O3 oxide film in the form of fine La2O3 and LaCrO3 spinel particles.

  9. Phenyl Functionalized Sol-gel Silica Sorbent for Capillary Microextraction and Chromia-Based Sol-gel Ucon Stationary Phase for Capillary Gas Chromatography

    Science.gov (United States)

    McLean, Michael M.

    The first chapter of this thesis presents an introduction to sol-gel methodology whose usefulness as a synthetic route will be demonstrated with two applications in chromatography. The first application involves the fabrication of a capillary micro-extraction (CME) device by coating a phenyl functionalized extracting phase on the inner surface of a fused silica capillary for analyte pre-concentration. The device was coupled on-line to a RP-HPLC system and practicality was demonstrated using allergens as target analytes. The allergens chosen as model analytes are typically found in fragrance products and food. Most of the 26 fragrance allergens that are monitored by various government authorities have a phenyl organic moiety (a strong chromophore), thus making them appropriate probes for exploring the extraction efficiency of the coating using a UV detector. The CME device showed ppt level limit of detection which makes it suitable for trace analyses of allergens and similar compounds in a variety of matrices. The second application explores the feasibility of using sol-gel derived chromia-based stationary phase in gas chromatographic columns. The organic moiety of the stationary phase was derived from Ucon 75-H-90,000 while the inorganic backbone was prepared using chromium(III) dichloride hydroxide - methacrylic acid - aqua complex, 40% in isopropanol/acetone . Usefulness of prepared chromia-based GC stationary phase was examined for petrochemical application. Promising results were obtained using aliphatic-aromatics, polyaromatic hydrocarbons, BTEX test mixture, cycloalkanes, branched alkanes and akylbenzenes. The column was able to perform without degradation despite being rinsed multiples times sequentially with the following solvents: dichloromethane, methanol, water and finally methanol again. Maximum theoretical plate number calculated is around 2,400 plates/m. The plate number clearly needs improvement but is a promising result for the newly explored

  10. Microstructural evolution and mechanical, and corrosion property evaluation of Cu-30Ni alloy formed by Direct Metal Deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, S., E-mail: sudipb@umich.edu [University of Michigan, 2350 Hayward Street, 2040 G.G. Brown Laboratories, Ann Arbor, MI 48109 (United States); Dinda, G.P.; Dasgupta, A.K. [Center for Advanced Technologies, Focus: HOPE, Detroit, MI 48238 (United States); Natu, H.; Dutta, B. [POM Group Inc., Auburn Hills, MI 48326 (United States); Mazumder, J. [University of Michigan, 2350 Hayward Street, 2040 G.G. Brown Laboratories, Ann Arbor, MI 48109 (United States); POM Group Inc., Auburn Hills, MI 48326 (United States)

    2011-06-02

    Research highlights: > Cu-30Ni alloy was successfully deposited with CO{sub 2} laser DMD system on C71500 substrate. > The microstructure consists of a single solid solution phase. > Columnar dendrites growing into equiaxed dendrites form layer microstructure. > Dendrite growth direction and angle relative to substrate was maintained in each layer. > Lattice parameter of solid solution phase is longer than reported lattice parameters. - Abstract: In the current investigation Cu-30Ni alloy was successfully laser deposited on a rolled C71500 plate substrate by Direct Metal Deposition technology. The microstructural investigation of the clad was performed using optical and scanning electron microscopy. The phase and crystal structure analysis was performed using X-ray diffraction technique and transmission electron microscopy. The microstructure consisted of columnar and equiaxed dendrites with face centered cubic crystal structure. The dendrites grew epitaxially from the substrate and layer and bead boundaries. Dendrites' growth direction <0 0 1> and growth angle 60{sup o} was maintained in each layer. The average primary dendritic arm spacing at the bottom part of the layers was about 7.5 {mu}m and average secondary dendritic arm spacing in the upper part of the layer varied between 2 {mu}m and 4.5 {mu}m. The lattice parameter of the identified phase was found to be longer than that reported in literature. The reported lattice parameters in literature are however from samples processed under equilibrium conditions. The microhardness of the clad was found to be less than the substrate but very consistent along the clad. Cu-30Ni clad specimen showed higher ultimate tensile strength but lower yield strength and percentage elongation as compared to the C71500 substrate. DMD Cu-30Ni clad/C71500 substrate specimen showed the worst mechanical properties. The corrosion resistance of the specimens was found to decrease in the order DMD Cu-30Ni clad, half-and-half DMD Cu

  11. Optimizing cathodic electrodeposition parameters of ceria coating to enhance the oxidation resistance of a Cr{sub 2}O{sub 3}-forming alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu, E-mail: xuw388@mail.usask.ca; Fan, Fan; Szpunar, Jerzy A.

    2016-07-29

    Nano-ceria coating was deposited onto a chromium oxide forming alloy through galvanostatic cathodic electro-deposition method in cerium nitrate electrolyte. The electrochemical behavior and influence of main deposition parameters of current density, deposition time, and temperature were studied. It was seen that the crystal size decreased with increasing of current density while micro-cracks were also observed at higher current density. Slightly increasing of crystal size and smoothing of surface morphology were seen with increasing of deposition time. It was reported that the bath temperature has the most significant effect on crystal size and surface morphology of the deposit. Green rust as corrosion product was also observed with deposition temperatures higher than 35 °C. Optimized deposition parameters were used to produce homogeneous, continuous and green rust-free coatings which enhance the oxidation resistance of alloy 230. The electro-deposition process was found to be an accessible and efficient method to prepare nano-crystalline ceria coating. - Highlights: • Electrodeposition was used to make ceria coating on a chromium oxide forming alloy; • Deposition parameters of current density, time and temperature were investigated; • Crystal size and morphology of coating vary with changing of deposition parameters; • Coating prepared with optimized parameters reduced oxidation rate of alloy 230.

  12. Cathode Formed by Thermal Evaporation of Ba:Al Alloy and Estimations of Barrier Height in an Organic LED

    Institute of Scientific and Technical Information of China (English)

    DING Lei; ZHANG Fang-Hui

    2011-01-01

    @@ It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vac- uum is applicable for organic laser emitting diodes (LEDs) as a thin film cathode.The alloy film obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the struc- ture: indium tin oxide (ITO)/4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline) aluminum(Alq) /barium:aluminum alloy.The experimental results show that devices with this alloy film cathode exhibit better current densityovoltage-luminance characteristics than those with a conventional pure AI cathode, and more weight of barium in aluminum leads to better performance of the devices.Characteristics of cur- rent density versus voltage for the electron-only devices are fitted by the Richardson-Schottky emission model, indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.%It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes (LEDs) as a thin Rim cathode. The alloy Him obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the structure: indium tin oxide (ITO)/4,4'-bis[N-(l-naphthyl)-N-phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline) aluminum(Alq3)/barium:aluminum alloy. The experimental results show that devices with this alloy film cathode exhibit better current density-voltage-luminance characteristics than those with a conventional pure Al cathode, and more weight of barium in aluminum leads to better performance of the devices. Characteristics of current density versus voltage for the electron-only devices are fitted by the Richardson-Schottky emission model, indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.

  13. Finite element modelling of shot peening and peen forming processes and characterisation of peened AA2024-T351 aluminium alloy

    Science.gov (United States)

    Gariepy, Alexandre

    The main purpose of this thesis was to develop and validate finite element (FE) simulation tools for shot peening and peen forming. The specific aim was to achieve quantitatively accurate predictions for both processes and demonstrate the potential of reliable FE modelling for scientific investigation and industrial applications. First, an improved dynamic impact model that takes into account the stochastic nature of shot peening was proposed by carefully studying its dimensions, introducing a dispersion of shot sizes and significantly reducing its computational cost. In addition, cyclic mechanical testing was conducted to define a suitable material constitutive theory for aluminium alloy (AA) 2024-T3/T351 subjected to shot peening. By combining a realistic shot peening model with an appropriate material law, fairly good residual stress predictions were achieved for three different sets of shot peening parameters. Second, an experimental and numerical characterization of AA2024-T351 shot peened with parameters representative of fatigue life improvement applications was conducted. Multiple techniques, such as micro-indentation, residual stress determination and electron backscatter diffraction, were combined to gain a better understanding of the influence of shot peening on the material. The potential uses of finite element simulation to complement experimental data were also studied. The material heterogeneity arising from the random impact sequence was investigated and it was found that the impact modelling methodology could provide useful information on such heterogeneities. Third, a novel peen forming simulation methodology was introduced. The impact model provided the necessary input data as part of a multiscale approach. Numerically calculated unbalanced induced stress profiles were input into shell elements and the deformed shape after peen forming was computed as a springback analysis. In addition, a simple interpolation method was proposed to model the

  14. Corrosion behaviour of Al86.0Co7.6Ce6.4 glass forming alloy with different microstructures

    Science.gov (United States)

    Li, C. L.; Wang, P.; Sun, S. Q.; Voisey, K. T.; McCartney, D. G.

    2016-10-01

    It has been extensively reported that Al-TM-RE amorphous alloy has excellent mechanical properties and corrosion resistance. In this paper, the corrosion behaviour of an Al86.0Co7.6Ce6.4 glass forming alloy with different microstructures is investigated through electrochemical experiments and microscopy. Results show the effect of microstructure. Laser and electron beam surface melting processes produce rapidly solidified microstructures with different extents of passivation compared to the as-cast alloy. An amorphous surface layer produced by these surface treatments had superior corrosion resistance compared with the crystalline alloy. As-cast and laser treated Al86.0Co7.6Ce6.4 suffered localised corrosion in the Al/Al11Ce3 eutectic region whereas the amorphous material exhibited uniform corrosion. Compared with the electrochemical behaviour of AA2024 and Alclad 2024, the fully amorphous layer prepared by combined laser-electron beam treatment exhibited advantages such as the more negative corrosion potential, the higher pitting potential and the uniform corrosion mechanism, which indicates that this material is a potential anode candidate in the protection of AA2024.

  15. Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-01

    A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.

  16. Influence of potassium pyrophosphate in electrolyte on coated layer of AZ91 Mg alloy formed by plasma electrolytic oxidation

    Institute of Scientific and Technical Information of China (English)

    Jin-Young CHO; Duck-Young HWANG; Dong-Heon LEE; Bongyoung YOO; Dong-Hyuk SHIN

    2009-01-01

    The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation (PEO) process for AZ91 Mg alloy was investigated. The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis. The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%-18% (mass fraction) of phosphorous. The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer, which strongly implied that the phosphorous ion might be concentrated at the barrier layer. Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate. The polarization resistance (Rp) of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65×107 Ω/cm2, which was higher than that (Rp=3.56×104 Ω/cm2) of the sample coated from electrolyte without potassium pyrophosphate. The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance.

  17. Anti-corrosion film formed on HAl77-2 copper alloy surface by aliphatic polyamine in 3 wt.% NaCl solution

    Science.gov (United States)

    Yu, Yinzhe; Yang, Dong; Zhang, Daquan; Wang, Yizhen; Gao, Lixin

    2017-01-01

    The corrosion inhibition of a polyamine compound, N-(4-amino-2, 3-dimethylbutyl)-2, 3-dimethylbutane-1, 4-diamine (ADDD), was investigated for HAl77-2 copper alloy in 3 wt.% NaCl solution. Electrochemical measurements, scanning electron microscopy (SEM), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR) techniques were employed for this research. The results show that ADDD strongly suppresses the corrosion of HAl77-2 alloy. The inhibition efficiency of ADDD is 98.6% at 0.5 mM, which is better than benzotriazole (BTAH) at the same concentration. Polarization curves indicate that ADDD is an anodic type inhibitor. Surface analysis suggests that a protective film is formed via the interaction of ADDD and copper. FT-IR reveals that the inhibition mechanism of ADDD is dominated by chemisorption onto the copper alloy surface to form an inhibition film. Furthermore, quantum chemical calculation and molecular dynamics (MD) simulations methods show that ADDD adsorbs on HAl77-2 surface via amino group in its molecule.

  18. Metallurgical investigation of defects in super alloy 718 mill forms intended for aeroengine applications; Metallurgische Schadensanalyse an Halbzeugen aus der Superlegierung 718 fuer Triebwerksapplikationen

    Energy Technology Data Exchange (ETDEWEB)

    Gopala Krishna, V.; Srinivas, M. [Defence Metallurgical Research Lab., Hyderabad (India); Janakiram, G.D. [Utah State Univ., Logan, UT (United States); Murty, C.H.V.S.; Venugopal Reddy. A. [Regional Center for Military Airworthiness (Materials), Hyderabad (India)

    2008-10-15

    Super alloy 718 finds extensive utilization, particularly in aero engine industry, due to its excellent strength, low cycle fatigue and creep resistance. The alloy was manufactured using vacuum induction melting followed by vacuum arc remelting techniques. The electrodes, after thermo-mechanical processing to hot rolled square bar and flat forms, were ultrasonically inspected prior to machining of aeroengine compressor blades. During machining, crack-like defects were noticed. Visual / Stereo microscopic examination revealed that the defect was along the length of airfoil and was located at mid airfoil width. The defects were filled with dark gray colored debris. Fractographic examination of the crack facets revealed flaky gray region containing number of cracks and bright region with dimpled rupture features covered with debris. Analysis of the debris indicated the presence of oxygen in addition to the elements present in the material, suggesting that the debris is essentially an oxide. These features were correlated with processing histories and defect morphologies. (orig.)

  19. Influence of multi-step heat treatments in creep age forming of 7075 aluminum alloy: Optimization for springback, strength and exfoliation corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Arabi Jeshvaghani, R.; Zohdi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Shahverdi, H.R., E-mail: shahverdi@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Bozorg, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [School of Materials Science and Engineering, MA University of Technology, P.O. Box 16765-3197, Tehran (Iran, Islamic Republic of)

    2012-11-15

    Multi-step heat treatments comprise of high temperature forming (150 Degree-Sign C/24 h plus 190 Degree-Sign C for several minutes) and subsequent low temperature forming (120 Degree-Sign C for 24 h) is developed in creep age forming of 7075 aluminum alloy to decrease springback and exfoliation corrosion susceptibility without reduction in tensile properties. The results show that the multi-step heat treatment gives the low springback and the best combination of exfoliation corrosion resistance and tensile strength. The lower springback is attributed to the dislocation recovery and more stress relaxation at higher temperature. Transmission electron microscopy observations show that corrosion resistance is improved due to the enlargement in the size and the inter-particle distance of the grain boundaries precipitates. Furthermore, the achievement of the high strength is related to the uniform distribution of ultrafine {eta} Prime precipitates within grains. - Highlights: Black-Right-Pointing-Pointer Creep age forming developed for manufacturing of aircraft wing panels by aluminum alloy. Black-Right-Pointing-Pointer A good combination of properties with minimal springback is required in this component. Black-Right-Pointing-Pointer This requirement can be improved through the appropriate heat treatments. Black-Right-Pointing-Pointer Multi-step cycles developed in creep age forming of AA7075 for improving of springback and properties. Black-Right-Pointing-Pointer Results indicate simultaneous enhancing the properties and shape accuracy (lower springback).

  20. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystal and Polytetrahedral-Phase Forming Alloys

    Science.gov (United States)

    Kelton, K. F.; Gangopadhyay, Anup K.; Lee, G. W.; Hyers, Robert W.; Rathz, T. J.; Robinson, Michael B.; Rogers, Jan R.

    2003-01-01

    From extensive ground based work on the phase diagram and undercooling studies of Ti-Zr-Ni alloys, have clearly identified the composition of three different phases with progressively increasing polytetrahedral order such as, (Ti/Zr), the C14 Laves phase, and the i-phase, that nucleate directly from the undercooled liquid. The reduced undercooling decreases progressively with increasing polytetrahedral order in the solid, supporting Frank s hypothesis. A new facility for direct measurements of the structures and phase transitions in undercooled liquids (BESL) was developed and has provided direct proof of the primary nucleation of a metastable icosahedral phase in some Ti-Zr-Ni alloys. The first measurements of specific heat and viscosity in the undercooled liquid of this alloy system have been completed. Other than the importance of thermo-physical properties for modeling nucleation and growth processes in these materials, these studies have also revealed some interesting new results (such as a maximum of C(sup q, sub p) in the undercooled state). These ground-based results have clearly established the necessary background and the need for conducting benchmark nucleation experiments at the ISS on this alloy system.

  1. Optimum synthesis conditions of nanometric Fe50Ni50 alloy formed by chemical reduction in aqueous solution

    Indian Academy of Sciences (India)

    Marwa A Mohamed; Azza H El-Maghraby; Mona M Abd El-Latif; Hassan A Farag

    2013-10-01

    In the present article, various nanometric Fe50Ni50 alloys were synthesized by chemical reduction of the corresponding metal ions, with hydrazine in an aqueous solution. Process variables of reaction temperature, pH of the hydrazine solution and concentration of metal ions were varied in order to determine the optimum synthesis conditions regarding quality, productivity and cost. It is found that pH of hydrazine solution, at low concentration of metal ions, is the most crucial variable affecting the reaction rate, average crystallite and particle sizes of the synthesized nanometric Fe50Ni50 alloy, followed by the total concentration of metal ions. Thus, increase of pH of hydrazine solution acts as an efficient stabilizer in reducing the particle size. On the contrary, at high concentration of metal ions, the structural characteristics of the nanometric Fe50Ni50 alloy are almost insensitive to reaction temperature and pH of hydrazine solution, but the reduction rate is remarkably sensitive to reaction temperature. Based on these results, it is decided that a reaction temperature of 80 °C, pH of the hydrazine solution of 12.5 and concentration of metal ions of 0.6 M represent the optimum synthesis conditions. The role of pH of hydrazine solution in reducing the alloy’s average particle size as well as efficient stabilizer confirms tremendous effect of synthesis conditions on the alloy structure and therefore, the importance of this study for industrial production of nanometric Fe50Ni50 alloy.

  2. Nanoporous alumina formed by self-organized two-step anodization of Ni{sub 3}Al intermetallic alloy in citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stepniowski, Wojciech J., E-mail: wstepniowski@wat.edu.pl [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland); Cieslak, Grzegorz; Norek, Malgorzata; Karczewski, Krzysztof; Michalska-Domanska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jozwik, Pawel; Bojar, Zbigniew [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Anodic porous alumina was formed by Ni{sub 3}Al intermetallic alloy anodization. Black-Right-Pointing-Pointer The anodizations were conducted in 0.3 M citric acid. Black-Right-Pointing-Pointer Nanopores geometry depends on anodizing voltage. Black-Right-Pointing-Pointer No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni{sub 3}Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni{sub 3}Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 {mu}m/h was found for the anodization at 0 Degree-Sign C and 2.0 V. The highest one - 2.29 {mu}m/h - was noticed for 10.0 V and 30 Degree-Sign C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 Degree-Sign C) to 32.0 nm (12.0 V, 0 Degree-Sign C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 Degree-Sign C) to 177.9 nm (12.0 V, 30 Degree-Sign C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/{mu}m{sup 2} (2.0 V, 0 Degree-Sign C) to 94.9 pores/{mu}m{sup 2} (12.0 V, 0 Degree-Sign C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni{sub 3}Al intermetallic alloy are depending on the

  3. Investigation of Abnormal Grain Growth in a Friction Stir Welded and Spin-Formed Al-Li Alloy 2195 Crew Module

    Science.gov (United States)

    Tayon, Wesley A.; Domack, Marcia S.; Hoffman, Eric K.; Hales, Stephen J.

    2013-01-01

    In order to improve manufacturing efficiency and reduce structural mass and costs in the production of launch vehicle structures, NASA is pursuing a wide-range of innovative, near-net shape manufacturing technologies. A technology that combines friction stir welding (FSW) and spin-forming has been applied to manufacture a single-piece crew module using Aluminum-Lithium (AL-Li) Alloy 2195. Plate size limitations for Al-Li alloy 2195 require that two plates be FSW together to produce a spin-forming blank of sufficient size to form the crew module. Subsequent forming of the FSW results in abnormal grain growth (AGG) within the weld region upon solution heat treatment (SHT), which detrimentally impacts strength, ductility, and fracture toughness. The current study seeks to identify microstructural factors that contribute to the development of AGG. Electron backscatter diffraction (EBSD) was used to correlate driving forces for AGG, such as stored energy, texture, and grain size distributions, with the propensity for AGG. Additionally, developmental annealing treatments prior to SHT are examined to reduce or eliminate the occurrence of AGG by promoting continuous, or uniform, grain growth

  4. Structure of the glass-forming metallic liquids by ab-initio and classical molecular dynamics, a case study: Quenching the Cu60Ti20Zr20 alloy

    Science.gov (United States)

    Amokrane, S.; Ayadim, A.; Levrel, L.

    2015-11-01

    We consider the question of the amorphization of metallic alloys by melt quenching, as predicted by molecular dynamics simulations with semi-empirical potentials. The parametrization of the potentials is discussed on the example of the ternary Cu-Ti-Zr transition metals alloy, using the ab-initio simulation as a reference. The pair structure in the amorphous state is computed from a potential of the Stillinger-Weber form. The transferability of the parameters during the quench is investigated using two parametrizations: from solid state data, as usual and from a new parametrization on the liquid structure. When the adjustment is made on the pair structure of the liquid, a satisfactory transferability is found between the pure components and their alloys. The liquid structure predicted in this way agrees well with experiment, in contrast with the one obtained using the adjustment on the solid. The final structure, after quenches down to the amorphous state, determined with the new set of parameters is shown to be very close to the ab-initio one, the latter being in excellent agreement with recent X-rays diffraction experiments. The corresponding critical temperature of the glass transition is estimated from the behavior of the heat capacity. Discussion on the consistency between the structures predicted using semi-empirical potentials and ab-initio simulation, and comparison of different experimental data underlines the question of the dependence of the final structure on the thermodynamic path followed to reach the amorphous state.

  5. Capacitive behaviour and electronic structure of passive films formed on nickel base alloy type Inconel 600; influence of Cr and Fe. Comportement capacitif et structure electronique des films passifs formes sur l'alliage a base de nickel du type Inconel 600 (75Ni-16Cr-8Fe); influence du chrome et du fer

    Energy Technology Data Exchange (ETDEWEB)

    Hakiki, N.E.; Da Cunha Belo, M. (Centre National de la Recherche Scientifique (CNRS), 94 - Vitry-sur-Seine (France). Centre d' Etudes de Chimie Metallurgique)

    1994-08-01

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

  6. Electrochemical and Spectroscopic Study of Benzotriazole Films Formed on Copper, Copper-zinc Alloys and Zinc in Chloride Solution

    OpenAIRE

    Milošev, I.; Kosec, T.

    2009-01-01

    The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole (BTA) was studied using potentiodynamic measurements, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The addition of benzotriazole affects the dissolution of the materials investigated. Benzotriazole, generally known as an inhibitor of copper corrosion, is als...

  7. Towards the problem of forming full strength welded joints on aluminum alloy sheets. Part II: AA7475

    Science.gov (United States)

    Kalashnikova, Tatiana; Tarasov, Sergey; Eliseev, Alexander; Fortuna, Anastasiya

    2016-11-01

    The microstructural evolution in welded joint zones obtained both by friction stir welding and ultrasonic- assisted friction stir welding on dispersion hardened 7475 aluminum alloy has been examined together with the analysis of mechanical strength and microhardness. It was established that ultrasonic-assisted friction stir provided leveled microhardness profiles across the weld zones as well as higher joint strength as compared to those of standard friction stir welding.

  8. Effects of TiN film coating on electrochemical behaviors ofnanotube formed Ti-xHf alloys

    Institute of Scientific and Technical Information of China (English)

    Kang LEE; Won-Gi KIM; Joo-Young CHO; Sang-Won EUN; Han-Cheol CHOE

    2009-01-01

    Ti-xHf (x=10%, 20%, 30% and 40%, mass fraction) alloys were prepared by arc melting, and the microstructure was controlled for 24 h at 1 000 ℃ in argon atmosphere. The formation of nanotube was conducted by anodizing on Ti-Hf alloys in 1.0 mol/L H3PO4 electrolytes with small amounts of NaF at room temperature. And then TiN coatings were coated by DC-sputtering on the anodized surface. Microstructures and nanotube morphology of the alloys were examined by field emission scanning electron microscopy(FE-SEM) and X-ray diffractometry(XRD). The corrosion properties of the specimens were examined through potentiodynamic test (potential range from -1 500 to 2 000 mV) in 0.9 % NaCl solution by potentiostat. The microstructure shows the acicular phase and α′ phase with Hf content. The amorphous oxide surface is transformed to crystalline anatase phase. TiN coated nanotube surface has a good corrosion resistance.

  9. Characterization of air-formed surface oxide film on a Co-Ni-Cr-Mo alloy (MP35N) and its change in Hanks' solution

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Akiko, E-mail: nag-bcr@tmd.ac.jp [Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Tsutsumi, Yusuke [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Suzuki, Yuta [Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Faculty of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Katayama, Keiichi [Faculty of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Hanawa, Takao [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Yamashita, Kimihiro [Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan)

    2012-05-01

    The air-formed surface oxide films used for stents were characterized to determine their composition and chemical state on a Co-Ni-Cr-Mo alloy. The change of the films in Hanks' solution was used to estimate the reconstruction of the film in the human body. Angle-resolved X-ray photoelectron spectroscopy was used to characterize the composition of the film and substrate, as well as the film's thickness. The surface oxide film on the Co-Ni-Cr-Mo alloy (when mechanically polished) consists of oxide species of cobalt, nickel, chromium, and molybdenum, contains a large amount of OH{sup -}, and has a thickness of approximately 2.5 nm. Cations exist in the oxide as Co{sup 2+}, Ni{sup 2+}, Cr{sup 3+}, Mo{sup 4+}, Mo{sup 5+}, and Mo{sup 6+}. Chromium is enriched and cobalt and nickel are depleted in the oxide; however, nickel is enriched and cobalt is depleted in the substrate alloy just under the surface oxide film. Concentration of chromium was low and that of nickel was high at small take-off angles. This indicates that distribution of chromium is greater in the inner layer, but nickel is distributed more in the outer layer of the surface oxide film. During immersion in Hanks' solution, cobalt and nickel dissolved, and the film composition changed to mostly chromium oxide (Cr{sup 3+}), along with small amounts of cobalt, nickel, and molybdenum oxides, and calcium phosphate containing magnesium, potassium, and carbonate. After immersion in Hanks' solution, the thickness of the surface layer containing calcium phosphate increased to more than 4 nm, while the amount of OH{sup -} increased. The amount of cobalt and nickel in the surface oxide film and in the substrate alloy just below the oxide decreased during immersion.

  10. THREE-DIMENSIONAL VISU ALIZATION OF DEGENERATE FERRITE FORMED BELOW TTT-DIAGRAM BAY IN AN Fe-C-Mo ALLOY

    Institute of Scientific and Technical Information of China (English)

    K.M. Wu; M. Enomoto

    2003-01-01

    The evolution of degenerate ferrite in an Fe-0.28wt%C-3.0wt%Mo alloy isothermally reacted for 10ks at 20℃ below TTT diagram bay temperature have been revealed utilizing serial sectioning in conjunction with computer reconstruction and visualization.The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary. The degenerate morphology of ferrite may be attributed to repeated nucleation, growth and coalescence of adjacent ferrite crystals. The shape of individual ferrite crystals appears to be rod-like.

  11. Influence of Mn-Co Spinel Coating on Oxidation Behavior of Ferritic SS Alloys for SOFC Interconnect Applications

    OpenAIRE

    Venkatachalam, Vinothini; Molin, Sebastian; Kiebach, Wolff-Ragnar; Ming CHEN; Hendriksen, Peter Vang

    2014-01-01

    Chromia forming ferritic stainless steels (SS) are being considered for intermediate temperature solid oxide fuel cell interconnect applications. However, protective coatings are in general needed to avoid chromium volatilization and poisoning of cathodes from chromium species. Mn-Co spinel is one of the promising candidates to prevent chromium outward diffusion, improve oxidation resistance and ensure high electrical conductivity over the lifetime of interconnects. In the present study, unif...

  12. Super plastic forming of the Cd-17.4 Zn alloy; Conformado superplastico de la aleacion Cd-17.4 Zn

    Energy Technology Data Exchange (ETDEWEB)

    Llanes Briceno, J. A.; Torres Villasenor, G. [Instituto de Investigaciones en Materiales, UNAM, Mexico, D.F. (Mexico)

    2000-06-01

    In the present work the necessary steps to carry on the superplastic forming of the Cd-17.4 Zn alloy are defined. The use of either atmospheric pressure or gas pressure as forming tools is analyzed. The optimum values of the variables involved (temperature, maximum strain and sensitivity index) are determined while a method for the characterization of future superplastic alloys is set forth. The experimental characterization of the superplastic forming is achieved with free bulging of circular membranes of 12, 16, 24, 32 and 40 mm in diameter and with three different membrane thicknesses (0.4, 0.6 and 0.8 mm). [Spanish] Se definen los pasos necesarios para el conformado superplastico de la aleacion Cd-17.4Zn. Se comparan la presion atmosferica y el gas a presion como herramientas de conformado. Se determinan los valores optimos de las variables involucradas (temperatura, deformacion maxima e indice de sensibilidad) y se plantea una metodologia para la caracterizacion de futuras aleaciones superplasticas. El conformado superplastico se caracteriza experimentalmente mediante el inflado libre de membranas circulares de 12, 16, 24, 32 y 40 mm de diametro y tres diferentes espesores (0.4, 0.6 y 0.8 mm).

  13. Effects of benzotriazole on anodized film formed on AZ31B magnesium alloy in environmental-friendly electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Guo Xinghua [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin (China); An Maozhong, E-mail: mzan@hit.edu.c [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin (China); Yang Peixia; Li Haixian; Su Caina [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin (China)

    2009-08-12

    An environmental-friendly electrolyte of silicate and borate, which contained an addition agent of 1H-benzotriazole (BTA) with low toxicity (LD50 of 965 mg/kg), was used to prepare an anodized film on AZ31B magnesium alloy under the constant current density of 1.5 A/dm{sup 2} at room temperature. Effects of BTA on the properties of the anodized film were studied by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), loss weight measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results demonstrated that anodized growth process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependant on the BTA concentration, which might be attributed to the formation of an BTA adsorption layer on magnesium substrate surface. When the BTA concentration was 5 g/L in the electrolyte, a compact and thick anodized film could provide excellent corrosion resistance for AZ31B magnesium alloy.

  14. Investigation of rare earth sealing of porous micro-arc oxidation coating formed on AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    M.Laleh; Farzad Kargar; A.Sabour Rouhaghdam

    2012-01-01

    Magnesium and its alloys have been used in many industries,but they are reactive and require protection against aggressive environments.In this study,oxide coatings were applied on AZ91D magnesium alloy using micro-arc oxidation (MAO) process.Then,in order to seal the pores of the MAO coatings,the samples were immersed in cerium bath for different times.The surface morphologies and compositions of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS),respectively.The corrosion behavior of the coatings was investigated with electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 wt.% NaCl solution.The amount of the porosity of the coating was measured by electrochemical method.It was found that the sealing treatments by immersion in cerium bath successfully sealed the pores of the MAO coatings.The results of the corrosion tests showed that the MAO coating which was sealed in Ce bath for 10 min enhanced the corrosion resistance of the substrate significantly.Furthermore,this coating had the lowest amount of the porosity among the coatings.

  15. Prediction of two-dimensional topological insulator by forming a surface alloy on Au/Si(111) substrate

    Science.gov (United States)

    Chuang, Feng-Chuan; Hsu, Chia-Hsiu; Chou, Hsin-Lei; Crisostomo, Christian P.; Huang, Zhi-Quan; Wu, Shih-Yu; Kuo, Chien-Cheng; Yeh, Wang-Chi V.; Lin, Hsin; Bansil, Arun

    2016-01-01

    Two-dimensional (2D) topological insulators (TIs), which can be integrated into the modern silicon industry, are highly desirable for spintronics applications. Here, using first-principles electronic structure calculations, we show that the Au/Si(111)-√{3 } substrate can provide a platform for hosting 2D TIs obtained through the formation of surface alloys with a honeycomb pattern of adsorbed atoms. We systematically examined elements from groups III to VI of the periodic table at 2/3 monolayer coverage on Au/Si(111)-√{3 }, and found that In, Tl, Ge, and Sn adsorbates result in topologically nontrivial phases with band gaps varying from 0 to 50 meV. Our scanning tunneling microscopy and low-energy electron diffraction experiments confirm the presence of the honeycomb pattern when Bi atoms are deposited on Au/Si(111)-√{3 }, in accord with our theoretical predictions. Our findings pave the way for using surface alloys as a potential route for obtaining viable 2D TI platforms.

  16. Silicon-substituted hydroxyapatite coating with Si content on the nanotube-formed Ti–Nb–Zr alloy using electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yong-Hoon [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, OH (United States); Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, OH (United States)

    2013-11-01

    The purpose of this study was to investigate the electrochemical characteristics of silicon-substituted hydroxyapatite coatings on the nanotube-formed Ti–35Nb–10Zr alloy. The silicon-substituted hydroxyapatite (Si–HA) coatings on the nanotube structure were deposited by electron beam-physical vapor deposition and anodization methods, and biodegradation properties were analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy measurement. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD). The Si–HA layers were deposited with rough features having highly ordered nanotube structures on the titanium alloy substrate. The thickness of the Si–HA coating was less than that of the HA coating. The XRD results confirmed that the Si–HA coating on the nanotube structure consisted of TiO{sub 2} anatase, TiO{sub 2} rutile, hydroxyapatite, and calcium phosphate silicate. The Si–HA coating surface exhibited lower I{sub corr} than the HA coating, and the polarization resistance was increased by substitution of silicon in hydroxyapatite. - Highlights: • Silicon substituted hydroxyapatite (Si–HA) was coated on nanotubular titanium alloy. • The Si–HA coating thickness was less than single hydroxyapatite (HA) coating. • Si–HA coatings consisted of TiO{sub 2}, HA, and Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4}. • Polarization resistance of the coating was increased by Si substitution in HA.

  17. The mixed-spin ternary-alloy in the form of ABpC1- p on the Bethe lattice

    Science.gov (United States)

    Albayrak, Erhan

    2011-04-01

    The ABpC1-p type of mixed ferromagnetic-ferrimagnetic ternary-alloy with A (spin-3/2), B (spin-1) and C (spin-5/2) ions was studied on the Bethe lattice with the odd numbered shells containing only A ions, while the even numbered shells either containing B or C ions randomly. The phase diagrams were obtained on the (R=|JAC|/JAB,kTc/JAB) and (p, kTc/JAB) planes for given values of p and R, respectively, with the coordination numbers z=3, 4, 5 and 6. The explicit dependence of the phase diagrams on z and each shell of the Bethe lattice having only one type of ion lead to some differences when compared with the previous works. The model presents one or two compensation temperatures for appropriate values of the system parameters.

  18. Electroless plating of low-resistivity Cu–Mn alloy thin films with self-forming capacity and enhanced thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Sung-Te, E-mail: stchen@mail.hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Dali 412, Taichung, Taiwan (China); Chen, Giin-Shan [Department of Materials Science and Engineering, Feng Chia University, Seatwen 407, Taichung, Taiwan (China)

    2015-11-05

    Previous studies have typically used sputter deposition to fabricate Cu–Mn alloy thin films with concentrated solute additions which have exceeded several atomic percentages, and the electrical resistivity values of the resultant films from previous studies are relatively high, ranging from 2.5 to 3.5 μΩ-cm. Herein, we proposed a different approach by using electroless process to plate dilute Cu–Mn (0.1 at.%) alloy thin films on dielectric layers (SiO{sub 2}). Upon forming-gas annealing, the Mn incorporated into Cu–Mn films was segregated toward the SiO{sub 2} side, eventually converting itself into a few atomic layer thickness at the Cu/SiO{sub 2} interface, and forming films with a low level of resistivity the same as that of pure Cu films (2.0 μΩ-cm). The interfacial layer served as not only a diffusion barrier, but also an adhesion promoter that prevented the film’s agglomeration during annealing at elevated temperatures. The mechanism for the dual-function performance by the Mn addition was elucidated by interfacial bonding analysis, as well as dynamic (adhesive strength) and thermodynamic (surface-tension) measurements. - Highlights: • Electroless plating is proposed to grow dilute (0.1%) Cu–Mn films on SiO{sub 2} layers. • Adequate annealing results in a self-forming of MnO{sub x} at the Cu/SiO{sub 2} interface. • The role of interfacial MnO{sub x} as a barrier and adhesion promoter is demonstrated. • The treated dilute film has a low ρ level of pure Cu, in contrast to concentrated films. • Its potential as a single entity replacement of Cu interconnect is presented.

  19. 喷射成形硅铝合金镀覆工艺研究%Study of deposition technology on spray formed silicon-aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    李忠宝; 付银辉; 李元朴

    2012-01-01

    The electroless nickel plating and gold electroplating processes on the surface of spray formed silicon-aluminum alloy (CE11) were studied. The variation of surface morphology and chemical composition on CE11 silicon-aluminum alloy during deposition were analyzed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The quality of deposit was tested by thermal shock, high-temperature baking, and welding tests. It was found that an electroless plated coating with good adhesion can be obtained on the surface of CE11 silicon-aluminum alloy when electroless nickel plating was carried out after roughening with a mixed solution of ammonium hydrogen fluoride and nitric acid, ultrasonic film removing, zinc immersion, and nickel pre-plating. The deposit after gold electroplating retains good adhesion after baking at 400 ℃, which meets the eutectic welding requirement of gold-germanium, gold-tin alloy, etc.%研究了喷射成形硅铝合金(CE11)材料表面化学镀镍和镀金工艺,使用电子显微镜(SEM)及能谱分析仪(EDS)分析了沉积过程中CE11硅铝合金表面形貌和沉积层化学成分,采用热震、高温烘烤、焊接试验等方法检测了硅铝合金样件的镀层质量.结果发现,CE11硅铝合金经氟化氢铵和硝酸混合溶液粗化、超声波去膜、浸锌、预镀镍后化学镀镍,可以获得结合力良好的化学镀层,镀金后能耐400℃烘烤而仍然保持很好的结合力,能够满足金锗、金锡等合金的共晶焊接使用要求.

  20. Effects of sodium tungstate on characteristics of microarc oxidation coatings formed on magnesium alloy in silicate-KOH electrolyte

    Institute of Scientific and Technical Information of China (English)

    DING Jun; LIANG Jun; HU Li-tian; HAO Jing-cheng; XUE Qun-ji

    2007-01-01

    Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation(MAO) technique in silicate-KOH electrolyte with addition of 0-6.0 g/L Na2WO4. The MAO processes in base electrolyte with different concentrations of Na2WO4 were studied. The microstructure, compositions and mechanical tribological characteristics of the oxide coatings were also investigated by SEM, XRD, XPS, microhardness analysis and ball-on-disc friction testing, respectively. It is found that the addition of Na2WO4 into the base electrolyte has direct effect on the characteristics of voltage-time curves and breakdown voltage in MAO process. The number of micropores at top of the coating surface is increased by the addition of Na2WO4. The fraction of forsterite Mg2SiO4 in the oxide coating increases with increasing concentration of Na2WO4 in base electrolytes. Furthermore, the microhardness and wear resistance of oxide coatings are enhanced as well.

  1. The Influence of Various Additives on the Properties of Peo Coatings Formed on AZ31 mg Alloy

    Science.gov (United States)

    Rehman, Zeeshan Ur; Ahn, Byung-Hyun; Jeong, Yeong Seung; Song, Jung-Il; Koo, Bon-Heun

    2016-03-01

    In this work, plasma electrolytic oxidation (PEO) ceramic coatings were prepared on magnesium AZ31B alloy. Various electrolyte solutions including phosphate, aluminate and silicate as additives and NaOH + Na2SiF6 as constant agent were used to prepare the coatings. Influence of the additives on chemical composition and structure of the PEO coatings were examined by means of scanning electron microscope (SEM) and XRD. From structural analysis it was found that coatings prepared in the aluminate-based electrolyte have the best structural features. Microhardness and tribological characteristics of the PEO coatings were investigated using Vickers hardness test and pin-on-disc test. Microhardness for aluminate-based coating was found to be 1169.63HV while those for silicate-and phosphate-based coatings were 1093.42HV and 285.91HV, respectively. Wear rate of the aluminate-based coating was found to be lowest than all other coatings having a value of 2.78×10-3mg/Nm.

  2. Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingbiao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); School of Science, Lanzhou University of Technology, Lanzhou 730050 (China); Liang, Jun, E-mail: jliang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu, Baixing; Peng, Zhenjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Qing [School of Science, Lanzhou University of Technology, Lanzhou 730050 (China)

    2014-04-01

    Highlights: • The PEO coating growth rate increased with the cathodic voltage increasing. • Higher cathodic voltage resulted in more compact coating structure. • The compact structure led to low surface roughness and high wear resistance. - Abstract: Plasma electrolytic oxidation (PEO) coatings were prepared on aluminium alloy using pulsed bipolar power supply at constant anodic voltage and different cathodic voltages. The samples were prepared to attain the same coating thickness by adjusting the processing time. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and tribometer were employed to investigate the microstructure, element content, phase composition and wear resistance of the coatings respectively. It was found that the coating growth rate enhanced obviously and the coatings exhibited a more compact structure with thicker inner layer and lower surface roughness when the cathodic voltage increased. The coatings were mainly composed of crystalline γ-Al{sub 2}O{sub 3} and amorphous silicate oxides and their relative content changed with the cathodic voltage. The wear resistance of the coatings improved significantly with the increase of cathodic voltage.

  3. Influence of Lanthanum Ion-Implantation on Adhesive Property of Oxide Film Formed on Co-40Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    JIN Hui-ming; ZHANG Lin-nan; LIU Xiao-jun

    2008-01-01

    The isothermal and cyclic oxidizing kinetics of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1 000 ℃ in air by thermal gravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to examine the Cr2O3 oxide film's morphology after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by La-doping and its influence on the formation of Cr2O3 film. Acoustic emission (AE) method was used in situ to monitor the cracking and spalling of oxide films during oxidizing and subsequent air-cooling stages. Laser Raman spectrum was used to examine the stress changes within oxide films. A theoretical model was proposed relating to the film fracture process and was used to analyze the AE spectrum both on time domain and AE-event number domain. It was found that lanthanum implantation remarkably reduced the isothermal oxidizing rate of Co-40Cr and improved the anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement were mainly that the implanted lanthanum reduced the grain size and internal stress of Cr2O3 oxide, increased the high temperature plasticity of oxide film, and remarkably reduced the number and size of Cr2O3/Co-40Cr interfacial defects.

  4. Effect of deformation temperature and strain rate on semi-solid deformation behavior of spray-formed Al-70 %Si alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG Di; YANG Bin; ZHANG Ji-shan; ZHANG Yong-an; XIONG Bai-qing

    2005-01-01

    Spray-formed Al-70%Si(mass fraction) alloys were deformed by compression in the semi-solid state.The effects of the deformation temperature, strain rate and the microstructure were studied. Two strain rates(1 s-1and 0.1 s-1) and six deformation temperatures (600 ℃, 720 ℃ , 780 ℃, 900 ℃, 1 000 ℃ and 1 100 ℃) were chosen. The stress-strain curve exhibits a peak at low strain and then decreases to a plateau before it starts to increase again as the strain increases. The stress required for deformation at lower strain rate and at higher deformation temperatures is less than those at higher strain rate and at lower deformation temperatures. Four mechanisms of semisolid deformation can be used to explain the different behaviors of the stress-strain curves under different conditions.

  5. Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

    Science.gov (United States)

    Lee, Seung-Jun; Kim, Seong-Kweon; Jeong, Jae-Yong; Kim, Seong-Jong

    2014-12-01

    Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

  6. Microstructural characteristics of oxide layers formed on Mg–9 wt%Al–1 wt%Zn alloy via two-step plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Min [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Ko, Young Gun, E-mail: younggun@ynu.ac.kr [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Shin, Dong Hyuk, E-mail: dhshin@hanyang.ac.kr [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of)

    2014-12-05

    Graphical abstract: - Highlights: • The oxide layer on Mg alloy sample treated by two-step PEO coating was fabricated. • The breakdown voltage of sample via two-step PEO coating was observed to be ∼475 V. • Mg{sub 2}Zr{sub 5}O{sub 12} and ZrO{sub 2} were synthesized in the oxide layer via two-step PEO coating. - Abstract: A study investigated the formation and microstructural features of the oxide layer formed on Mg–9 wt%Al–1 wt%Zn alloy coated by two-step plasma electrolytic oxidation (PEO) where an acid electrolyte with K{sub 2}ZrF{sub 6} was used for the second PEO coating after the initial coating was done in an alkaline electrolyte. The microstructure, chemical compositions, and constituent compounds of the oxide layers were observed using scanning electron microscopy, electron probe micro-analyzer, and X-ray diffraction, respectively. The microstructural observations showed that the micropores caused by plasma discharge were formed in the oxide layers which were comprised of three different parts, namely, inner, intermediate, and outer layers from the substrate to the surface of the sample. The outer layer contained the highest concentration of Zr element whose amount decreased toward the substrate whereas the concentration of Mg element increased in the order of outer, intermediate, and inner layers. This finding suggested that the outer oxide layer was mainly comprised of ZrO{sub 2} compound while both ZrO{sub 2} and Mg{sub 2}Zr{sub 5}O{sub 12} compounds existed together as the main compounds in the intermediate oxide layer.

  7. Microstructure of Al2O3 scales formed on NiCrAl alloys. Ph.D. Thesis - Case Western Reserve Univ.

    Science.gov (United States)

    Smialek, J. L.

    1981-01-01

    The structure of transient scales formed on pure and Y or Zr-doped Ni-15Cr-13Al alloys oxidized for 0.1 hr at 1100 C was studied by the use of transmission electron microscopy. Crystallographically oriented scales were found on all three alloys, but especially for the Zr-doped NiCrAl. The oriented scales consisted of alpha-(Al,Cr)2O3, Ni(Al,Cr)2O4 and gamma-Al2O3. They were often found in intimate contact with each other such that the close-packed planes and directions of one oxide phase were aligned with those of another. The prominent structural features of the oriented scales were approximately equal to micrometer subgrains; voids, antiphase domain boundaries and aligned precipitates were also prevalent. Randomly oriented alpha-Al2O3 was also found and was the only oxide ever observed at the immediate oxide metal interface. These approximately 0.15 micrometer grains were populated by intragranular voids which decreased in size and number towards the oxide metal interface. A sequence of oxidation was proposed in which the composition of the growing scale changed from oriented oxides rich in Ni and Cr to oriented oxides rich in Al. At the same time the structure changed from cubic spinels to hexagonal corundums with apparent precipitates of one phase in the matrix of the other. Eventually randomly oriented pure alpha-Al2O3 formed as the stable oxide with an abrupt transition: there was no gradual loss of orientation, no gradual compositional change or no gradual decrease in precipitate density.

  8. Structure analysis of CoPt alloy film with metastable ordered phases of L11 and Bh formed on Ru(0001 underlayer

    Directory of Open Access Journals (Sweden)

    Ohtake Mitsuru

    2014-07-01

    Full Text Available CoPt alloy films of 40 nm thickness are prepared on MgO(111 substrates with and without Ru(0001 underlayer at 300 °C by radio-frequency magnetron sputtering. CoPt films with the close-packed plane parallel to the substrate surface grow epitaxially on the Ru underlayer as well as on the MgO substrate. Flat surfaces with the arithmetical mean roughness value of 0.2 nm are realized for both films. The crystal structure is determined by considering the atomic stacking sequence of close-packed plane and the order degree. The film formed on MgO substrate consists of an fcc-based L11 ordered crystal, whereas the film grown on Ru underlayer involves an hcp-based Bh ordered crystal in addition to the L11 ordered crystal. The order degrees of films formed on MgO substrate and Ru underlayer are 0.30 and 0.34, respectively. The L11 crystal consists of two variants whose stacking sequences of close-packed plane are ABCABC… and ACBACB…, while the Bh crystal is a single-crystal with the stacking sequence of ABAB… Formation of Bh crystal is promoted on the Ru underlayer. The film formed on Ru underlayer shows a strong perpendicular magnetic anisotropy reflecting the magnetocrystalline anisotropies of L11 and Bh crystals.

  9. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    Science.gov (United States)

    Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.

    2015-12-01

    ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.

  10. POWDER-GAS DISCHARGE, FORMED AT MELTING OF ALUMINIUM CASTING ALLOYS IN INDUCTION CRUCIBLE FURNACE IAT- 6

    Directory of Open Access Journals (Sweden)

    G. A. Rumjantseva

    2009-01-01

    Full Text Available The carried out analysis of powder-gas discharge shows that volumes and composition of the forming dust are determined by composition of recycled material, type of lubrication for machines under high pressure, quality of recycled material preparation and technology of refining processing.

  11. Observation On Void Formed In Oxide Scale Of Fe-Cr-Ni Alloy At 1073k In Dry And Humid Environments

    Directory of Open Access Journals (Sweden)

    Akbar Kaderi

    2012-01-01

    Full Text Available Void formation in oxide scale during high temperature oxidation is a common phenomenon. Over a long period of time voids will affect the mechanical property of scales by influencing the cracking and spalling. Voids formed in dry environment are different than that of formed in humid environment. With the presence of water vapor in humid environment the formation of void will increase, thus greater number of void compared to that in dry environment. Fe-Cr-Ni alloy samples were exposed isothermally at 1073 K in air (P_(O_2 = 0.21atm = 2.1×?10?^(5 Pa and  humid (air + steam environments. XRD analysis done to all samples confirms that Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 and NiO phases exist in the scale. EDX analysis done shows varying compositions of Fe,Cr,Ni and O in outer and inner oxide scale, oxide scale/metal interface and metal. Field emission scanning electron microscope (FE-SEM was used to investigate voids formed in the cross sections of the oxidized samples. Volume fraction of voids in the oxide scale was calculated in accordance to the cross sectional area fraction of voids in the scale. It shows that Fe-Cr-Ni alloy samples exposed in humid environment has as high as 71% more voids than that exposed in dry environment. It is concluded that the humid environment increased the number of void formed in the oxide scale, thus facilitates the exfoliation of protective scale during the high temperature oxidation. ABSTRAK: Pembentukan gelembung udara di dalam lapisan oksida ketika proses pengoksidaan di suhu tinggi merupakan satu fenomena biasa. Pada satu jangka masa yang panjang gelembung-gelembung ini akan memberi kesan kepada sifat mekanikal oksida dengan mempengaruhi pembentukan keretakan dan pengelupasan oksida. Gelembung udara yang terbentuk di dalam persekitaran kering berbeza daripada yang terbentuk di dalam persekitaran lembap. Dengan adanya wap air, pembentukan gelembung akan bertambah berbanding yang terbentuk di dalam

  12. Effect of some process parameters on geometric errors in twopoint incremental forming for Al-Cu-Mg Aluminum Alloy

    Science.gov (United States)

    Li, Xiaoqiang; Han, Kai; Yu, Honghan; Zhang, Yongsheng; Li, Dongsheng

    2016-08-01

    Two point incremental forming receives widespread study with its advantages of economy and flexibility in small batch products, such as aircraft parts. Aircraft parts, however, are rigorous in their shape errors. In this paper, one real airplane part is selected and formed with different process parameters to investigate the shape error level of part. Comparing the geometric errors caused by different process parameters, such as tool diameter, step size, feed rate and tool path, it is found that the geometric errors reduce as tool diameter increases. Meanwhile, the effect of step size is not linear. Influence law of feed rate is various with different other parameters. The bidirectional tool path, having opposite processing direction at adjacent layer, reduces the errors.

  13. Semi-solid Forming of a Damper Housing with Dendritic and Non-dendritic Al-Si-Mg Alloy

    Institute of Scientific and Technical Information of China (English)

    ChenCM; YangCC; ChaoCG

    2001-01-01

    A motorcycle component of damper housing was made by semi-solid forming process. This was used to investigate the effect of microstructures of feedstock on the formability of semisolid process. The soundness and microstructures of casting parts made by dendritic and non-dendritic feedstock were investigated. Separating of liquid phase was found in the casting produced by dendritic feedstock, which might result in defects of porosity, while uniform microstructures were found in the casting produced by no...

  14. PIIID-formed (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti coatings on NiTi shape memory alloy for medical applications.

    Science.gov (United States)

    Sun, Tao; Wang, Lang-Ping; Wang, Min; Tong, Ho-Wang; Lu, William W

    2012-08-01

    (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti composite coatings were fabricated on NiTi shape memory alloy via plasma immersion ion implantation and deposition (PIIID). Surface morphology of samples was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Cross-sectional morphology indicated that the PIIID-formed coatings were dense and uniform. X-ray diffraction (XRD) was used to characterize the phase composition of samples. X-ray photoelectron spectroscopy (XPS) results showed that the surface of coated NiTi SMA samples was Ni-free. Nanoindentation measurements and pin-on-disc tests were carried out to evaluate mechanical properties and wear resistance of coated NiTi SMA, respectively. For the in vitro biological assessment of the composite coatings in terms of cell morphology and cell viability, osteoblast-like SaOS-2 cells and breast cancer MCF-7 cells were cultured on NiTi SMA samples, respectively. SaOS-2 cells attached and spread better on coated NiTi SMA. Viability of MCF-7 cells showed that the PIIID-formed composite coatings were noncytotoxic and coated samples were more biocompatible than uncoated samples.

  15. Crystallization behavior of Ti61.67Zr17.15Ni14.80Cu6.38 glass-forming alloy

    Institute of Scientific and Technical Information of China (English)

    范金铎; 高逸群; 黎仕增

    2004-01-01

    Ti61.67 Zr17.15 Ni14.80 Cu6.38 (atom fraction,%) metallic glass has applications in brazing. Using the hammer-and-anvil technique, Ti61.67 Zr17.15 Ni14.80 Cu6.38 metallic glass was prepared. The crystallization behavior for this metallic glass was investigated by differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and transmission electron microscopy(TEM). Th ere are three stages in DSC curves of crystallization. The reduced glass temperature Trg is 0.42. The kinetic parameters of crystallization were calculated by a set of equations of the maximum crystallization rate. The crystalline phase formed in the MSI(Metastable stage Ⅰ) is Zr2Cu, in the MSⅡ is α-Ti and in the MSⅢ is Ti2 Ni. This kind of alloy has lower glass forming ability, and the Ti61.67 Zr17. 15 Ni14. 80 Cu6.38 metallic glass has lower thermal stability.

  16. Corrosion mechanisms for metal alloy waste forms: experiment and theory Level 4 Milestone M4FT-14LA0804024 Fuel Cycle Research & Development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang-Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Taylor, Christopher D. [The Ohio State Univ., Columbus, OH (United States). Fontana Corrosion Center; Kim, Eunja [Univ. of Nevada, Las Vegas, NV (United States); Goff, George Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kolman, David Gary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-31

    This document meets Level 4 Milestone: Corrosion mechanisms for metal alloy waste forms - experiment and theory. A multiphysics model is introduces that will provide the framework for the quantitative prediction of corrosion rates of metallic waste forms incorporating the fission product Tc. The model requires a knowledge of the properties of not only the metallic waste form, but also the passive oxide films that will be generated on the waste form, and the chemistry of the metal/oxide and oxide/environment interfaces. in collaboration with experimental work, the focus of this work is on obtaining these properties from fundamental atomistic models. herein we describe the overall multiphysics model, which is based on MacDonald's point-defect model for passivity. We then present the results of detailed electronic-structure calculations for the determination of the compatibility and properties of Tc when incorporated into intermetallic oxide phases. This work is relevant to the formation of multi-component oxides on metal surfaces that will incorporate Tc, and provide a kinetic barrier to corrosion (i.e. the release of Tc to the environment). Atomistic models that build upon the electronic structure calculations are then described using the modified embedded atom method to simulate metallic dissolution, and Buckingham potentials to perform classical molecular dynamics and statics simulations of the technetium (and, later, iron-technetium) oxide phases. Electrochemical methods were then applied to provide some benchmark information of the corrosion and electrochemical properties of Technetium metal. The results indicate that published information on Tc passivity is not complete and that further investigation is warranted.

  17. In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

    Science.gov (United States)

    Lan, Si; Wei, Xiaoya; Zhou, Jie; Lu, Zhaoping; Wu, Xuelian; Feygenson, Mikhail; Neuefeind, Jörg; Wang, Xun-Li

    2014-11-01

    In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr56Cu36Al8, an average glass former, follows continuous nucleation and growth, while that of Zr46Cu46Al8, a better glass former, is characterized by site-saturated nucleation, followed by slow growth. Possible mechanisms for the observed differences and the relationship to the glass forming ability are discussed.

  18. In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Si; Wei, Xiaoya; Wu, Xuelian; Wang, Xun-Li, E-mail: xlwang@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Ave., Kowloon (Hong Kong); Zhou, Jie; Lu, Zhaoping [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing (China); Feygenson, Mikhail; Neuefeind, Jörg [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-11-17

    In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr{sub 56}Cu{sub 36}Al{sub 8}, an average glass former, follows continuous nucleation and growth, while that of Zr{sub 46}Cu{sub 46}Al{sub 8}, a better glass former, is characterized by site-saturated nucleation, followed by slow growth. Possible mechanisms for the observed differences and the relationship to the glass forming ability are discussed.

  19. Preparation and Characterization of Amorphous Layer on Aluminum Alloy Formed by Plasma Electrolytic Deposition (PED)

    Institute of Scientific and Technical Information of China (English)

    GUANYong-jun; XIAYuan

    2004-01-01

    In this investigation, protective layers were formed on aluminum substrate by Plasma Electrolytic Deposition (PED) using sodium silicate solution. The relation between the thickness of the layer and process time were studied. XRD, SEM, EDS were used to study the layer's structure, composition and micrograph. The results show that the deposited layers are amorphous and contain mainly oxygen, silicon, and aluminum. The possible formation mechanism of amorphous[Al-Si-O] layer was proposed: During discharge periods, Al2O3 phase of the passive film and SiO32- near the substrate surface are sintered into xSiO2(1-x)Al2O3 and then transformed into amorphous [Al-Si-O] phase.

  20. The effect of C atom concentration on the electronic properties of boron carbonitride alloy nanotube in zig-zag form

    Indian Academy of Sciences (India)

    H Milani Moghaddam

    2011-06-01

    Electronic properties of single-walled boron nitride nanotube in zig-zag form are numerically investigated by replacing B atoms with C atoms. Using a tight-binding Hamiltonian, the methods based on Green’s function theory, Landauer formalism and Dyson equation, the electronic density of states and electronic conductance in boron nitride nanotube and boron carbonitride nanotube are calculated. Our calculations indicate that in a boron nitride nanotube, the localized states associated with C impurities appear as the concentration of C atoms increases. The boron carbonitride nanotube thus behaves like a semiconductor. Also, by increasing the C atom concentration, the voltage in the first step on the – characteristics decreases, whereas the corresponding current increases.

  1. De-alloyed platinum nanoparticles

    Science.gov (United States)

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  2. Rare earth effect of yttrium on formation and property of Cr2O3 oxide film formed on Co-Cr binary alloy

    Institute of Scientific and Technical Information of China (English)

    JIN Huiming; FELIX A. Congrado; AROYAVE M. Hayara

    2006-01-01

    The isothermal oxidizing kinetics of Co-40Cr alloy and its yttrium ion-implanted samples were studied at 1000℃ in air by thermal-gravity analysis (TGA). Scanning electronic microscopy (SEM) was used to examine the Cr2O3 oxide film's morphology after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by Y-doping and its influence on formation of Cr2O3 film. Acoustic emission (AE) method was used in situ to monitor the cracking and spalling of oxide films formed on both samples during oxidizing and subsequent air-cooling stages. Theoretical model simulating the film fracture process was proposed to analyze the acoustic emission spectrum both on time domain and on AE-event number domain. It is found that yttrium ionimplantation can remarkably reduce the isothermal oxidizing rate of Co-40Cr and improve the anti-cracking and anti-spalling properties of Cr2O3 oxide film. Reasons for the improvement are mainly that the implanted yttrium can reduce the grain size of Cr2O3 oxide, increase the high temperature plasticity of oxide film, and remarkably reduce the number and size of Cr2O3/Co-40Cr interfacial defects.

  3. Effect of Al2O3 Micro-powder Additives on the Properties of Micro-arc Oxidation Coatings Formed on 6061 Aluminum Alloy

    Science.gov (United States)

    Wang, Ping; Wu, Ting; Xiao, You Tao; Pu, Jun; Guo, Xiao Yang; Huang, Jun; Xiang, Chun Lang

    2016-09-01

    Al2O3 micro-powder was suspended in the basis electrolyte to form micro-arc oxidation (MAO) coatings on 6061 aluminum alloy by MAO. During the stage of micro-arc oxidation, Al2O3 micro-powder with negative surface charge was melted by the micro-arc around the anode and incorporated into the MAO coatings. With the continuous addition of Al2O3 micro-powder, the oxidation voltages rose up firstly and then decreased. The surface and cross-sectional morphologies showed that the size of micropores decreased and the MAO coatings surface got loosened following the variation in Al2O3 micro-powder concentration. As a consequence of the changing coating structure, the corrosion resistance of the coatings decreased apparently. The micro-hardness of the coatings increased firstly and then decreased, opposite to the trend of the average friction coefficient. It revealed the minimum average friction coefficient of MAO coatings and maximum adhesion between the coatings and substrate when 2.0 g/L Al2O3 micro-powder was added into electrolyte. There were visible cracks and peelings on the coating surface merely at 4.0 g/L after thermal shock tests. The x-ray diffraction results indicated that the addition of Al2O3 micro-powder had less effect on the phase composition of MAO coatings.

  4. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  5. AZ系列镁合金热模拟挤压过程中挤压力的研究%Extrusion Force of AZ Series Mg Alloy During Thermal Simulated Extrusion Forming

    Institute of Scientific and Technical Information of China (English)

    彭建; 周绸; 李权

    2011-01-01

    AZ 10, AZ31, AZ61 and AZ91 magnesium alloys were deformed with simulated extrusion system on Gleeble 1500D, which can determine the extrusion force during extrusion forming process. The microstructure of the alloys and the evolution of extrusion force were investigated. The results show that the extrusion force increases gradually with the increase of alloy element. Aimed at the same magnesium alloy, the deformed alloy with previous homogenization before extrusion has more extrusion force than that without homogenization, and dynamic recrystallization is a decisive factor in extrusion force during extrusion forming.%通过在Gleeble1500D热模拟试验机上对AZ10、AZ31、AZ61和AZ91镁合金进行模拟挤压,并对热模拟挤压成形过程中的挤压力进行测定,研究AZ系列镁合金热模拟挤压成形过程挤压力及其组织变化.研究结果表明,在AZ系列镁合金中,随着合金元素含量的增多,挤压力逐渐增大,并且同种镁合金在挤压前经均匀化退火处理后所需的挤压力比未经均匀化处理的合金所需挤压力大,动态再结晶是影响其挤压力大小的决定性因素.

  6. Basic Study on Selective Laser Melting Technique Formed to Dental Co-Cr Alloy%选择性激光熔融技术成形牙科钴铬合金性能的初步研究

    Institute of Scientific and Technical Information of China (English)

    李勇; 张飚; 黄奇容; 王萍; 赵创; 罗朋

    2012-01-01

    Objective: To investigate the surface condition and ion releasing behavior of cobalt-chromium (Co - Cr) dental alloy formed by selective laser melting (SLM) technique. Methods: Before porcelain fused sintering process, the surface condition was observed using a scanning electron microscope(SEM) , and then the density and hardness of the two alloys were examined. After porcelain fused firing, the interface of porcelain and alloy was observed. Results; SLM technique provide Co -Cr alloy higher hardness than traditional casting method, hwever the density of two alloys were same. After degassing-preoxidation procedure and porcelain fused firing, the interface of the two alloys with porcelain all showed excellent combination. Conclusions: Considering the properties before and after porcelain fused sintering process, SLM technique is suitable to form dental Co - Cr alloy.%目的:通过测试选择性激光熔融(selective laser melting,SLM)技术制作的牙科钴铬(Co- Cr)合金的部分机械性能、表面显微结构、瓷熔附后的界面情况,以期为该技术的应用提供基础资料.方法:使用SLM技术制作牙科钴铬合金样品,用扫描电镜观察样品的表面形貌和显微结构、测试样品的密度和硬度;将样品经过除气-预氧化处理,用扫描电镜观察样品表面氧化膜的形貌和显微结构;将经过除气-预氧化处理的样品进行瓷熔附,用扫描电镜观察样品金-瓷界面的显微结构.结果:SLM制作的钴铬合金的硬度明显高于铸造钴铬合金;经过除气-预氧化处理后的氧化膜细密均匀;两种方法制作的合金在瓷熔附处理后的金-瓷界面均没有发现明显裂纹.结论:SLM技术比传统铸造技术具有一定的优越性,技术细节有待深入研究.

  7. New amorphous alloy with high glass forming ability on the Cu-Zr-Al-Gd system; Desenvolvimento de nova liga com estrutura amorfa no sistema Cu-Zr-Al-Gd

    Energy Technology Data Exchange (ETDEWEB)

    Mazzer, E.M.; Aliaga, L.C.R.; Bolfarini, C.; Botta Filho, W.J.; Kiminami, C.S., E-mail: eric_mazzer@hotmail.co [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The prediction of the Glass Forming Ability (GFA) in metallic alloys is usually performed by empirical or semi-empirical criteria in binary or ternary systems. For multi-component systems with more than three elements, the criteria or models become extremely complex making it impractical. In this paper we present the results on the GFA prediction of the Cu-Zr-Al-Gd alloys, where compositions had been selected for the synergy of the topological instability and electronegativity criteria which was increased by the average radio criterion for the quaternary system. Alloys were prepared and processed by arc-meting and die casting techniques. Characterization was made by x-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques. It was concluded that Cu{sub 39,2}Zr{sub 49}Al{sub 9}, {sub 80}Gd{sub 2} alloy presents high thermal stability expressed by great supercooled liquid region upper to 76 deg C. (author)

  8. Microstructure and Mechanical Performance of Cu-Sn-Ti-Based Active Braze Alloy Containing In Situ Formed Nano-Sized TiC Particles

    Science.gov (United States)

    Leinenbach, Christian; Transchel, Robert; Gorgievski, Klea; Kuster, Friedrich; Elsener, Hans Rudolf; Wegener, Konrad

    2015-05-01

    A Cu-Sn-Ti-based active brazing filler alloy was in situ reinforced with nanosized TiC particles by adding different amounts of a cellulose nitride-based binder. The TiC particles emanate from a reaction of the Ti within the filler alloy with the carbon from the binder that does not decompose completely during heating. The correlation between the microstructure and mechanical performance was studied. In addition, the effect of different binder amounts on the shear strength and cutting performance of brazed diamond grains was studied in shear tests and single grain cutting tests. The results clearly show that the mechanical performance of the brazed diamond grains can be improved by the formation of TiC particles. This is attributed to particle strengthening of the filler alloy matrix as well as to the decreasing grain size and more homogeneous distribution of the (Cu,Sn)3Ti5 phase with increasing amount of binder.

  9. M-Si-B合金非晶形成能力的CALPHAD模式评估%Evaluation of the amorphous-forming ability of M-Si-B ternary alloys using CALPHAD approach

    Institute of Scientific and Technical Information of China (English)

    长谷部光弘

    2005-01-01

    A thermodynamic study has been carried out on M-Si-B (M=Fe, Ni) ternary systems. A regular solution approximation based on the sublattice model was adopted to describe the Gibbs energy for the individual phases in the binary and ternary systems. Thermodynamic parameters for each phase were evaluated by using the experimental data. These parameters enabled us to obtain reproducible calculations of the isothermal and vertical section diagrams.The amorphous-forming ability of M-Si-B ternary alloys has been evaluated by introducing thermodynamic quantities obtained from the phase diagram calculations into Davies-Uhlmann kinetic formulations. For the computation, the timetemperature- transformation (TTT) diagram, which gives the time necessary for the formation of the detectable amount of crystal during transformation, was obtained at a finite temperature The critical cooling rate for amorphization could be defined as the minimum cooling speed that does not intersect the TTT curve and, hence, these critical cooling rates enable us to evaluate the glass-forming ability of M-Si-B ternary alloys. The driving force for the crystallization of the crystalline phase was derived, on the basis of the thermodynamic functions of each phase formulated by the present study. The calculated results showed good agreement with the experimental data on the compositional range of amorphization in these alloy systems.

  10. Fundamental Studies of the Durability of Materials for Interconnects in Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Frederick S. Pettit; Gerald H. Meier

    2006-06-30

    Ferritic stainless steels are a leading candidate material for use as an SOFC interconnect, but have the problem of forming volatile chromia species that lead to cathode poisoning. This project has focused both on optimization of ferritic alloys for SOFC applications and evaluating the possibility of using alternative materials. The initial efforts involved studying the oxidation behavior of a variety of chromia-forming ferritic stainless steels in the temperature range 700-900 C in atmospheres relevant to solid oxide fuel cell operation. The alloys exhibited a wide variety of oxidation behavior based on composition. A method for reducing the vaporization is to add alloying elements that lead to the formation of a thermally grown oxide layer over the protective chromia. Several commercial steels form manganese chromate on the surface. This same approach, combined with observations of TiO{sub 2} overlayer formation on the chromia forming, Ni-based superalloy IN 738, has resulted in the development of a series of Fe-22 Cr-X Ti alloys (X=0-4 wt%). Oxidation testing has indicated that this approach results in significant reduction in chromia evaporation. Unfortunately, the Ti also results in accelerated chromia scale growth. Fundamental thermo-mechanical aspects of the durability of solid oxide fuel cell (SOFC) interconnect alloys have also been investigated. A key failure mechanism for interconnects is the spallation of the chromia scale that forms on the alloy, as it is exposed to fuel cell environments. Indentation testing methods to measure the critical energy release rate (Gc) associated with the spallation of chromia scale/alloy systems have been evaluated. This approach has been used to evaluate the thermomechanical stability of chromia films as a function of oxidation exposure. The oxidation of pure nickel in SOFC environments was evaluated using thermogravimetric analysis (TGA) to determine the NiO scaling kinetics and a four-point probe was used to measure

  11. Anti-corrosion and wear properties of plasma electrolytic oxidation coating formed on high Si content Al alloy by sectionalized oxidation mode

    Science.gov (United States)

    Dai, Libin; Li, Wenfang; Zhang, Guoge; Fu, Nianqing; Duan, Qi

    2017-01-01

    In this study, a uniform and less defective ceramic coating was prepared on high Si content aluminium alloys by a sectionalized plasma electrolytic oxidation (PEO) mode. The PEO process of Al-9 wt. % Si binary alloy was performed under constant current mode followed by constant voltage mode. The surface micrographs and chemical compositions of different samples were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Micro-hardness and reciprocal-sliding testers were used to measure the coatings hardness and tribological performance. It was found that the sectionalized PEO mode could produce hard and anti-friction passive oxide layers with smaller holes and fewer cracks on the Al-Si alloy, comparing with the single constant current mode. In addition, the results of polarization curves and electrochemical impedance spectroscopy (EIS) tests conducted in 3.5 wt. % NaCl solution revealed that the coatings obtained by sectionalized PEO mode had a higher corrosion resistance and provided better corrosion protection for Al-Si alloy.

  12. RESEARCH OF GAS-FORMING ABILITY OF THE MATERIALS USED AT DEVELOPMENT OF DIVIDING COVERINGS FOR THE MOLDS OF CASTING OF ALUMINUM ALLOYS UNDER PRESSURE

    Directory of Open Access Journals (Sweden)

    A. M. Mihaltsov

    2012-01-01

    Full Text Available The methods of carrying out of experiments by determination of gas creating ability of different materials which are of interest from the point of view of molding of aluminum alloys under pressure are given and described, and the results of research are presented as well.

  13. Comparison of segregations formed in unmodified and Sr-modified Al–Si alloys studied by atom probe tomography and transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Barrirero, Jenifer [Department of Materials Science, Campus D3 3, Saarland University, D-66123 Saarbrücken (Germany); Nanostructured Materials, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Engstler, Michael [Department of Materials Science, Campus D3 3, Saarland University, D-66123 Saarbrücken (Germany); Ghafoor, Naureen [Nanostructured Materials, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Jonge, Niels de [Innovative Electron Microscopy, INM-Leibniz Institute for New Materials, Campus D2 2, Saarland University, D-66123 Saarbrücken (Germany); Odén, Magnus [Nanostructured Materials, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Mücklich, Frank, E-mail: muecke@matsci.uni-sb.de [Department of Materials Science, Campus D3 3, Saarland University, D-66123 Saarbrücken (Germany)

    2014-10-25

    Highlights: • Nucleation of nanoclusters is proposed to assist in the structural modification. • The role of Al in the Si-phase of unmodified and Sr-modified alloys is discussed. • Segregations in the Si-phase of unmodified and Sr-modified alloys are compared. • Solubilities of 430 ± 160 at-ppm Al and 40 ± 10 at-ppm Sr in the Si phase were determined. - Abstract: The mechanical properties of Al-7 wt.% Si can be enhanced by structural modifications of its eutectic phase. Addition of low concentrations of certain elements, in this case 150 wt-ppm Sr, is enough to cause a transition from a coarse plate-like Si structure to a finer coralline one. To fully understand the operating mechanism of this modification, the composition of the eutectic Si phase in unmodified and Sr-modified alloys was analysed and compared by atom probe tomography and (scanning) transmission electron microscopy. The unmodified alloy showed nanometre sized Al-segregations decorating defects, while the Sr-modified sample presented three types of Al–Sr segregations: (1) rod-like segregations that promote smoothening of the Al–Si boundaries in the eutectic phase, (2) particle-like segregations comparable to the ones seen in the unmodified alloy, and (3) planar segregations favouring the formation of twin boundaries. Al and Sr solubilities in Si after solidification were determined to be 430 ± 160 at-ppm and 40 ± 10 at-ppm, respectively. Sr predominantly segregates to the Si phase confirming its importance in the modification of the eutectic growth.

  14. TUNGSTEN BASE ALLOYS

    Science.gov (United States)

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  15. Materials Performance in USC Steam Portland

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Holcomb; J. Tylczak; R. Hu

    2011-04-26

    Goals of the U.S. Department of Energy's Advanced Power Systems Initiatives include power generation from coal at 60% efficiency, which requires steam conditions of up to 760 C and 340 atm, co-called advanced ultrasupercritical (A-USC) steam conditions. A limitation to achieving the goal is a lack of cost-effective metallic materials that can perform at these temperatures and pressures. Some of the more important performance limitations are high-temperature creep strength, fire-side corrosion resistance, and steam-side oxidation resistance. Nickel-base superalloys are expected to be the materials best suited for steam boiler and turbine applications above about 675 C. Specific alloys of interest include Haynes 230 and 282, Inconel 617, 625 and 740, and Nimonic 263. Further validation of a previously developed chromia evaporation model is shown by examining the reactive evaporation effects resulting from exposure of Haynes 230 and Haynes 282 to moist air environments as a function of flow rate and water content. These two alloys differ in Ti and Mn contents, which may form outer layers of TiO{sub 2} or Cr-Mn spinels. This would in theory decrease the evaporation of Cr{sub 2}O{sub 3} from the scale by decreasing the activity of chromia at the scale surface, and be somewhat self-correcting as chromia evaporation concentrates the Ti and Mn phases. The apparent approximate chromia activity was found for each condition and alloy that showed chromia evaporation kinetics. As expected, it was found that increasing the gas flow rate led to increased chromia evaporation and decreased chromia activity. However, increasing the water content in moist air increased the evaporation, but results were mixed with its effect on chromia activity.

  16. Effect of creep age forming on fatigue for 7B04 aluminum alloy%蠕变时效成形对7B04铝合金疲劳性能的影响

    Institute of Scientific and Technical Information of China (English)

    金兴; 万敏; 李超

    2011-01-01

    蠕变时效成形技术是利用金属的蠕变特性,将成形与时效处理同步进行的一种成形方法,能有效地提高材料的疲劳性能.本文针对7B04-T7451状态的铝合金进行蠕变时效成形,进而在成形试件的基础上进行疲劳试验.介绍了.-N曲线的一般数学表达式,将常用的幂函数表达式变换拟合得到材料疲劳寿命S-N曲线,通过SN曲线的比较发现,蠕变时效后7B04铝合金在中低应力区间疲劳寿命大幅提高.%Creep age forming technology is a method which uses the creep character of metal, combining forming and ageing heat treatment process to improve the fatigue property of material. A series of creep tests for 7B04-T7451 aluminum alloy were carried out, and then the formed aluminum alloy was taken to do fatigue tests. General mathematical expressions for S-N curve were introduced. The most used power function expression was transformed to fit the S-N curve. Compared with different S-N curves, the fatigue property of creep age formed aluminum alloy is improved at medium and low stress.

  17. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  18. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  19. Structure of the glass-forming metallic liquids by ab-initio and classical molecular dynamics, a case study: Quenching the Cu{sub 60}Ti{sub 20}Zr{sub 20} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Amokrane, S.; Ayadim, A.; Levrel, L. [Groupe “Physique des Liquides et Milieux Complexes,” Faculté des Sciences et Technologie, Université Paris-Est (Créteil), 61 av. du Général de Gaulle, 94010 Créteil Cedex (France)

    2015-11-21

    We consider the question of the amorphization of metallic alloys by melt quenching, as predicted by molecular dynamics simulations with semi-empirical potentials. The parametrization of the potentials is discussed on the example of the ternary Cu-Ti-Zr transition metals alloy, using the ab-initio simulation as a reference. The pair structure in the amorphous state is computed from a potential of the Stillinger-Weber form. The transferability of the parameters during the quench is investigated using two parametrizations: from solid state data, as usual and from a new parametrization on the liquid structure. When the adjustment is made on the pair structure of the liquid, a satisfactory transferability is found between the pure components and their alloys. The liquid structure predicted in this way agrees well with experiment, in contrast with the one obtained using the adjustment on the solid. The final structure, after quenches down to the amorphous state, determined with the new set of parameters is shown to be very close to the ab-initio one, the latter being in excellent agreement with recent X-rays diffraction experiments. The corresponding critical temperature of the glass transition is estimated from the behavior of the heat capacity. Discussion on the consistency between the structures predicted using semi-empirical potentials and ab-initio simulation, and comparison of different experimental data underlines the question of the dependence of the final structure on the thermodynamic path followed to reach the amorphous state.

  20. An Evaluation of a Borided Layer Formed on Ti-6Al-4V Alloy by Means of SMAT and Low-Temperature Boriding

    OpenAIRE

    Quantong Yao; Jian Sun; Yuzhu Fu; Weiping Tong; Hui Zhang

    2016-01-01

    In this paper, a nanocrystalline surface layer without impurities was fabricated on Ti-6Al-4V alloy by means of surface mechanical attrition treatment (SMAT). The grain size in the nanocrystalline layer is about 10 nm and grain morphology displays a random crystallographic orientation distribution. Subsequently, the low-temperature boriding behaviors (at 600 °C) of the SMAT sample, including the phase composition, microstructure, micro-hardness, and brittleness, were investigated in compariso...

  1. Phase and structural states in the NiTi-based alloy surface layer formed by electron-ion-plasma methods using tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Neiman, Aleksei A., E-mail: nasa@ispms.tsc.ru; Lotkov, Aleksandr I.; Gudimova, Ekaterina Y. [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Meisner, Ludmila L., E-mail: meisner2l@yahoo.com; Semin, Viktor O. [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The paper reports on a study of regularities of formation gradient nano-, submicron and microstructural conditions in the surface layers of the samples after pulsed electron-beam melting of tantalum coating on the substrate NiTi alloy. Experimentally revealed the presence of submicron columnar structure in the upper layers of the tantalum coating. After irradiation modified NiTi surface takes on a layered structure in which each layer differs in phase composition and structural phase state.

  2. A study on the relationships between corrosion properties and chemistry of thermally oxidised surface films formed on polished commercial magnesium alloys AZ31 and AZ61

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, Sebastián, E-mail: sfeliu@cenim.csic.es [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Samaniego, Alejandro [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Barranco, Violeta [Instituto de Ciencias de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Científicas, CSIC, Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049, Madrid (Spain); El-Hadad, A.A. [Physics Department, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo (Egypt); Llorente, Irene [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Serra, Carmen [Servicio de Nanotecnologia y Análisis de Superficies, CACTI, Universidade de Vigo, 36310 Vigo (Spain); Galván, J.C. [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2014-03-01

    Highlights: • Surface chemistry of heat treated magnesium alloys. • Relation between heat treatment and aluminium subsurface enrichment. • Relation between surface composition and corrosion behaviour. - Abstract: This paper studies the changes in chemical composition of the thin oxide surface films induced by heating in air at 200 °C for time intervals from 5 min to 60 min on the freshly polished commercial AZ31 and AZ61 alloys with a view to better understanding their protective properties. This thermal treatment resulted in the formation of layers enriched in metallic aluminium at the interface between the outer MgO surface films and the bulk material. A strong link was found between the degree of metallic Al enrichment in the subsurface layer (from 10 to 15 at.%) observed by XPS (X-ray photoelectron spectroscopy) in the AZ61 treated samples and the increase in protective properties observed by EIS (electrochemical impedance spectroscopy) in the immersion test in 0.6 M NaCl. Heating for 5–60 min in air at 200 °C seems to be an effective, easy to perform and inexpensive method for increasing the corrosion resistance of the AZ61 alloy by approximately two or three times.

  3. Effect of Nanosize SiO2 Particles Added into Electrolyte on the Composition and Morphology of Oxide Layers Formed in Alloy AK6M2 Under Microarc Oxidizing

    Science.gov (United States)

    Krishtal, M. M.; Ivashin, P. V.; Yasnikov, I. S.; Polunin, A. V.

    2015-11-01

    Oxide layers formed on AK6M2 aluminum-silicon alloy by microarc oxidizing (MO) are studied. The chemical and phase compositions and the morphology of the layers deposited from a base-composition electrolyte with different contents of added SiO2 powder are determined. It is shown that high-temperature phases form in the oxide layer at a specific concentration of SiO2 nanoparticles. This indicates elevation of the effective temperature in the zone of synthesis of the oxide layers in the process of MO. The addition of nanosize particles of SiO2 into the electrolyte influences positively the operating characteristics of the formed oxide layer.

  4. 钛合金表面氟化物-磷酸盐转化膜的制备及性能研究%Preparation and Properties of Fluoride-Phosphate Conversion Coating Formed on Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    叶君; 杜楠; 王力强; 尹茂生; 周国华; 王帅星

    2015-01-01

    目的:研究一种钛合金化学转化工艺,增强钛合金表面防护能力及其与涂层的结合能力。方法通过单因素实验确定TC1钛合金氟化物-磷酸盐转化工艺,采用SEM,EDS,XRD分析膜层的微观形貌及成分,同时测试转化膜的有关性能。结果在Na3 PO440 g/L,NaF 15 g/L,酸度调节剂A 25 mL/L,pH控制在4.4~4.6之间,温度30益条件下,可在TC1钛合金表面获得均匀一致的灰色转化膜。转化膜由许多细小的球状晶粒组成,主要相成分为Na3 TiOF5及Na2 TiF6。转化膜的摩擦系数仅为0.3~0.5,明显低于TC1基体。转化膜与TB06-9底漆的干性附着力为0级,浸泡48 h后的湿态附着力仍可达1级,远远好于TC1基体。结论氟化物-磷酸盐转化膜可以降低TC1钛合金的摩擦系数,提高其与有机涂层的附着力。%ABSTRACT:Objective A chemical conversion technique was researched to enhance the protective ability of titanium alloy surface and the adhesion between titanium alloy and organic coating. Methods The preparation technique of fluoride-phosphate conversion coating formed on TC1 alloy was determined by the single-factor experiments. The microstructure and composition of conversion coating were analyzed by SEM, EDS and XRD. Besides, the related properties of the conversion coating were researched. Results A uniform, coherent and gray conversion coating could be obtained on the surface of TC1 alloy when Na3 PO4 , NaF, Acidity Regu-lator A, pH and temperature were 40 g/L, 15 g/L, 25 mL/L, 4. 4~4. 6 and 30 ℃, respectively. The microstructure of the coa-ting showed many small spherical grains. The main phase components were Na3 TiOF5 and Na2 TiF6 . The friction coefficient of the fluoride-phosphate conversion coating was only 0. 3~0. 5, which was significantly lower than that of TC1 alloy. The dry adhesion level between conversion coating and TB06-9 organic coating was 0, and the wet adhesion level after 48 h immersion could still reach 1, both were far

  5. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio and...

  6. Effects of gravity on the mi-crostructure of Zr41Ti14-Cu12.5Ni10Be22.5 bulk glass forming alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The ZrTiCuNiBe alloy is melt and solidified by Bridgman unidirectional solidification on two gravity field orientations (the gravity field orientation is parallel and opposite to solidification direction). Effects of gravity on morphology and microstructure are investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). When gravity field orientation is parallel to solidification direction, less needle-like primary phase is embedded in a matrix eutectic; when gravity field orientation is opposite to solidification direction, a large amount of coarser needle-like primary phases were observed.

  7. Method of making quasicrystal alloy powder, protective coatings and articles

    Science.gov (United States)

    Shield, J.E.; Goldman, A.I.; Anderson, I.E.; Ellis, T.W.; McCallum, R.W.; Sordelet, D.J.

    1995-07-18

    A method of making quasicrystalline alloy particulates is disclosed wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture. 3 figs.

  8. GH4169合金热变形微观组织演变模型%Microstructure model of GH4169 alloy during hot forming

    Institute of Scientific and Technical Information of China (English)

    李志强; 张宁; 王宝雨; 侯红亮; 胡正寰

    2014-01-01

    基于等效位错密度建立G H4169高温合金的本构方程及微观组织演变模型,通过遗传算法结合热模拟压缩实验结果对模型参数进行求解;对有限元模拟软件DEFORM-3D进行二次开发,模拟工件的镦粗成形,得到了工件平均晶粒尺寸和再结晶百分数的分布情况,并与实验结果进行了对比分析。结果表明,二次开发的软件对微观组织演变的模拟结果与实验结果的平均误差在10%左右,验证了G H4169合金本构方程和微观组织演变模型的准确性,以及对软件二次开发的可行性。%The dislocation density-based constitutive equation and microstructural evolution model of GH 4169 alloy were estab-lished .Through the genetic algorithm and the isothermal compression test data ,the parameters of model were calculated .Based on the secondary development of DEFORM-3D ,the upsetting was simulated and the distribution of average grain size and recrystal-lized volume fraction were obtained and compared with the experimental results .The results show that the average error between the microstructural simulation and the experimental research was within 10% ,which verified that the dislocation density-based constitutive equation and microstructural evolution model of GH 4169 alloy are accurate and the secondary development is feasible .

  9. Effect of biologically relevant ions on the corrosion products formed on alloy AZ31B: an improved understanding of magnesium corrosion.

    Science.gov (United States)

    Jang, Yongseok; Collins, Boyce; Sankar, Jagannathan; Yun, Yeoheung

    2013-11-01

    Simulated physiological solutions mimicking human plasma have been utilized to study the in vitro corrosion of biodegradable metals. However, corrosion and corrosion product formation are different for different solutions with varied responses and, hence, the prediction of in vivo degradation behavior is not feasible based on these studies alone. This paper reports the role of physiologically relevant salts and their concentrations on the corrosion behavior of a magnesium alloy (AZ31B) and subsequent corrosion production formation. Immersion tests were performed for three different concentrations of Ca(2+), HPO4(2-), HCO3(-) to identify the effect of each ion on the corrosion of AZ31B assessed at 1, 3 and 10 days. Time-lapse morphological characterization of the samples was performed using X-ray computed tomography and scanning electron microscopy. The chemical composition of the surface corrosion products was determined by electron dispersive X-ray spectroscopy and X-ray diffraction. The results show that: (1) calcium is not present in the corrosion product layer when only Cl(-) and OH(-) anions are available; (2) the presence of phosphate induces formation of a densely packed amorphous magnesium phosphate corrosion product layer when HPO4(2-) and Cl(-) are present in solution; (3) octacalcium phosphate and hydroxyapatite (HAp) are deposited on the surface of the magnesium alloy when HPO4(2-) and Ca(2+) are present together in NaCl solution (this coating limits localized corrosion and increases general corrosion resistance); (4) addition of HCO3(-) accelerates the overall corrosion rate, which increases with increasing bicarbonate concentration; (5) the corrosion rate decreases due to the formation of insoluble HAp on the surface when HCO3(-), Ca(2+), and HPO4(2-) are present together.

  10. Method of producing superplastic alloys and superplastic alloys produced by the method

    Science.gov (United States)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  11. Analysis of laser alloyed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D.C.; Augustyniak, W.M.; Buene, L.; Draper, C.W.; Poate, J.M.

    1981-04-01

    Surface alloys of precious metals have many advantages over bulk alloys, the most obvious of which is cost reduction due to the reduced consumption of precious metal. There are several techniques for producing surface alloys. In this paper the laser irradiation technique is presented. The following lasers: CW CO/sub 2/, Q-switched Nd-YAG, frequency double Q-switched Nd-YAG, and pulsed ruby were used to irradiate and melt thin solid films of precious metals on metal substrates. This causes the surfaces to melt to a depth of approximately 10,000A. Alloying then takes place in the liquid phase where most metals are miscible. The high quench rates obtainable by this method of melting can result in the forming of metastable alloys. This melting and regrowth process is well understood and has been discussed in the literature over the last few years. This paper deals with two binary alloy systems, Au-Ni and Pd-Ti. Surface alloys of Au-Ni with a wide range of concentrations have been produced by laser irradiation of thin Au films on Ni. These films have been analyzed using Rutherford backscattering (RBS) and channeling. Many thin film metals other than Au have also been successfully alloyed using these methods. An example of a potential application is the laser surface alloying of Pd to Ti for corrosion passivation.

  12. 自生成钨基高密度合金中间层的钨/钢真空扩散连接%Diffusion Bonding Tungsten to Steel in Vacuum with Tungsten Heavy Alloy Interlayer Formed on Tungsten Surface

    Institute of Scientific and Technical Information of China (English)

    杨宗辉; 沈以赴; 李晓泉

    2013-01-01

    采用90W-6Mn-4Ni(质量分数)混合粉末/镍箔复合中间层,在加压5 MPa、连接温度1 100℃、保温10 min、30 min、60 min及120 min的工艺条件下,对纯钨(W)和0Cr13钢进行真空扩散连接.利用扫描电镜、能谱仪和电子万能试验机等手段研究接头的微观组织、成分分布、力学性能及断口特征.结果表明,连接接头均由钨母材/钨基高密度合金层/镍/钢母材组成.接头中的钨基高密度合金层由90W-6Mn-4Ni混合粉末液相烧结生成,其富Mn-Ni黏结相和钨颗粒相冶金结合且分布均匀,保温时间对该层的组织形态无明显影响.钨基高密度合金层与钨母材以加压钎焊机制实现了良好结合.接头抗剪强度为202~217 MPa时,断裂均发生在连接界面两侧的钨母材和钨基高密度合金层中,前者断口为典型的解理脆断,后者断口为钨颗粒相的W-W界面分离断裂及黏结相的韧性断裂.%Bonding between tungsten and 0Crl3 steel using a 90W-6Mn-4Ni (mass fraction) powder mixtures/Ni multi-interiayer, was carried out in vacuum at 1 100 ℃ for 10 min, 30 min, 60 min, 120 min with 5 MPa. The microstructures, composition distribution and fracture characteristics of the joints are studied by scanning electron microscope(SEM), energy dispersive spectroscopy(EDS) and their mechanical properties are tested by shear experiments. The results show that the joints comprised tungsten/tungsten heavy alloy layer/Ni/0Crl3 steel. Among them, the tungsten heavy alloy layer is formed through liquid phase sintering of 90W-6Mn-4Ni mixed powder. Holding time has no significant effect on the microstructure of tungsten heavy alloy layer, which composes of metallurgical bonded and evenly distributed MnNi-rich phase and tungsten phase. Good bonding between tungsten matrix and tungsten heavy alloy layer is realized based on press brazing mechanism. The shear strength of joints is from 202 MPa to 217 MPa. All fractures occur in bonding zone of

  13. Study on Semi-solid Formed Magnesium Alloy Surface Diffusion Permeated Aluminum Technology%半固态成形镁合金表面扩散渗铝技术的研究

    Institute of Scientific and Technical Information of China (English)

    王晓东; 李元东; 陈体军; 康燕平; 高坤

    2011-01-01

    采用化学扩散渗的方法对半固态成形ZA91D镁合金表面进行渗铝处理,在不同的扩散时间和扩散温度下得到渗铝层,用OM,EPMA和XRD对渗铝层进行显微组织形貌、物相组成分析,并对扩渗试样进行Tafel曲线测试及显微硬度测试.结果表明:在430,440℃恒温热扩渗8,12和16 h,扩渗层与基体之间都能形成连续且均匀细密的渗铝层,渗层主要由Mg17Al12,Al3Mg2和α-Mg等组成,且渗层的厚度是随扩散温度提高及扩散时间的延长而增加.热扩散渗铝处理可以明显提高镁合金的腐蚀电位,从而提高镁合金的耐蚀性能.经热扩散渗铝处理后,渗层的显微硬度(120~180HV)高于基体(60~80HV),从而提高镁合金的表面显微硬度.%The chemical thermal-diffusion on the surface of semi-solid formed AZ91D magnesium alloy by Al powder was carried out, the diffusion coating was obtained at different diffusion temperature and diffusion time. The micro-structural characteristic and phase structure of the diffusion coating of AZ91D magnesium alloy were investigated by using X-ray diffraction and Optics Microscope and Electron probe micro-analyzer. The results show that an ideal alumi-nized coating can be formed on the surfaces of ZA91D specimens after Al diffusion treatment at 430,440 ℃ for 8,12, 16 hours,the coatings are metallurgical boneded with the substrates. The aluminized coating is mainly composed of α-Mg, Mgi7 Alj2 and Al3 Mg2, and its thickness of diffusion layer is spread with the spread of temperature increase and extension of time to increase. The thermal diffusion aluminizing treatment can significantly improve the corrosion potential of magnesium alloys to improve corrosion resistance of magnesium alloys. The thermal diffusion aluminizing treatment, the a-luminized layer hardness of 120~180HV higher than the substrate 60~80HV, thereby increasing the surface hardness of magnesium alloy.

  14. Morphology and performances of the anodic oxide films on Ti6Al4V alloy formed in alkaline-silicate electrolyte with aminopropyl silane addition under low potential

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiali; Wang, Jinwei, E-mail: wangjw@ustb.edu.cn; Yuan, Hongye

    2013-11-01

    Oxide films on Ti6Al4V alloy are prepared using sodium hydroxide–sodium silicate as the base electrolyte with addition of aminopropyl trimethoxysilane (APS) as additive by potentiostatic anodizing under 10 V. APS is incorporated into the films during anodizing and the surface morphology of the oxide films is changed from particle stacked to honeycomb-like porous surfaces as shown by scanning electron microscopy (SEM) with Energy Disperse Spectroscopy (EDX). The surface roughness and aminopropyl existence on the oxide films result in their differences in wettability as tested by the surface profile topography and contact angle measurements. The anti-abrasive ability of the anodic films is improved with the addition of APS due to its toughening effects and serving as lubricants in the ceramic oxide films as measured by ball-on-disk friction test. Also, potentiodynamic corrosion test proves that their anticorrosive ability in 3.5 wt.% NaCl is greatly improved as reflected by their much lower corrosion current (I{sub corr}) and higher corrosion potential (E{sub corr}) than those of the substrate.

  15. Effects of Al2O3 Nano-Particles on Corrosion Performance of Plasma Electrolytic Oxidation Coatings Formed on 6061 Aluminum Alloy

    Science.gov (United States)

    Vakili-Azghandi, Mojtaba; Fattah-alhosseini, Arash; Keshavarz, Mohsen K.

    2016-12-01

    Corrosion resistance improvement of plasma electrolyte oxidation coatings on 6061 aluminum alloy in silicate electrolyte containing Al2O3 nano-particles was studied, with particular emphasis on the microstructure, coating growth, and corrosion behavior in 3.5 wt.% NaCl solution. The microstructure of coatings, their thickness, and phase composition were characterized using scanning electron microscopy and x-ray diffraction. All characterization data showed that the maximum coating thickness and lowest amount of porosity were obtained in a low concentration of KOH, a high concentration of Na2SiO3, and moderate concentration of Al2O3 nano-particles in the electrolyte. This combination describes the optimum plasma electrolytic oxidation electrolyte, which has the best conductivity and oxidizing state, as well as the highest incorporation of electrolyte components in the coating growth process. On the other hand, incorporation and co-deposition of Al2O3 nano-particles were more pronounced than SiO3 2- ions in some level of molar concentration, which is due to the higher impact of electron discharge force on the adsorption of Al2O3 nano-particles. The electrochemical results showed that the best protective behavior was obtained in the sample having a coat with the lowest porosity and highest thickness.

  16. Slurry Erosion Characteristics and Erosive Wear Mechanisms of Co-Based and Ni-Based Coatings Formed by Laser Surface Alloying

    Science.gov (United States)

    Shivamurthy, R. C.; Kamaraj, M.; Nagarajan, R.; Shariff, S. M.; Padmanabham, G.

    2010-02-01

    In the present work, an attempt has been made to study the slurry erosion properties and operating erosive wear mechanisms of Co-based Stellite 6 and Ni-based Colmonoy 88 coatings, and also to list the conditions at which maximum and minimum erosion rates occur. Laser surface alloying (LSA) has been done on 13Cr-4Ni steels with commercial Co-based Stellite 6 and Ni-based Colmonoy 88 powders. Slurry erosion tests have been conducted on LSA-modified steels for a constant slurry velocity of 12 m/s and for a fixed slurry concentration of 10 kg/m3 of irregular, sharp-edged SiO2 particles with average sizes of 375 and 100 μm and at impingement angles of 30, 45, 60, and 90 deg. A mixed (neither ductile nor brittle) mode of erosion behavior for Stellite 6 coatings and a brittle mode of erosion behavior for Colmonoy 88 coatings were observed when these materials were impacted with particles with an average size of 375 μm, whereas only a brittle mode of erosion was observed for both Stellite 6 and Colmonoy 88 coatings when impacted with particles with an average size of 100 μm. Mainly, chip formation, chip fracture, microcutting, plowing, and crater lip and platelet formation were observed for Stellite 6 coatings and progressive fracture of carbides, carbide pullout and carbide/boride intact were observed for the case of Colmonoy 88 coatings.

  17. Aspects of precipitation in alloy Inconel 718

    OpenAIRE

    Azadian, Saied

    2004-01-01

    A study was made of the microstructure of the Ni-base alloy Inconel 718 with emphasis on the precipitation and stability of intermetallic phases as affected by heat treatments. In addition the effect of the precipitation on selected mechanical properties namely hardness, creep notch sensitivity and hot ductlity were investigated. The materials studied were a spray-formed version and three wrought versions of the alloy. The spray-formed version of the alloy was of interest since it exhibited a...

  18. Alloy nanoparticle synthesis using ionizing radiation

    Science.gov (United States)

    Nenoff, Tina M.; Powers, Dana A.; Zhang, Zhenyuan

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  19. 7050铝合金蠕变时效成形本构模型研究%Research on constitutive model of 7050 aluminum alloy for creep age forming

    Institute of Scientific and Technical Information of China (English)

    吕凤工; 黄遐; 曾元松; 王永坤; 万敏

    2014-01-01

    To study the creep age constitutive model of 7050T451 aluminum alloy, the uniaxial creep tests were operated under different stress condition at 160℃. The changing tendency of creep strain, yield strength and microstructure with holding time were analyzed. Based on the precipitate hardening theory of high strength aluminum alloy, the constitutive equation which could describe the evolution of macroscopic and microscopic for creep age forming was established. Meanwhile, the material constants were fitted and optimized by using genetic algorithm. According to the result, the present model fits well with the experimental data under different stress levels, which can be used to simulate the process of creep age forming.%为研究7050T451铝合金蠕变时效本构模型,在160℃、不同应力条件下进行单轴拉伸蠕变试验,分析了蠕变应变、屈服强度和微观组织随时间的变化规律。基于高强铝合金析出强化理论,建立了能描述蠕变时效成形宏观及微观变化的本构方程,并运用遗传算法对材料常数进行拟合优化。研究表明,该模型在不同应力水平下与试验结果吻合良好,能够用来模拟分析蠕变时效成形过程。

  20. Research on hydraulic forming loading paths of aluminium alloy anti-collision energy-absorbing tube%铝合金防碰撞吸能管液压成形加载路径研究

    Institute of Scientific and Technical Information of China (English)

    汪奇超; 雷君相; 骆协海

    2011-01-01

    According to the need of the double diameter tube part forming, the axial feeding compensation and hydraulic pressure loading control to the hydraulic bulging process of aluminium alloy 6061 tube were put forward. By numerical simulation method and the analysis software ABAQUS 6. 10 , aluminum alloy 6061 tube hydraulic bulging loading paths were studied. Taking eventual thickness distribution of the forming parts and forming failure control as the basis, the axial feeding and liquid pressure loading path on forming quality was analyzed. Research shows that when the axle feeding rate is 27 mm and hydraulic pressure is 85 Mpa, the max thinning rate of the anti-collision energy-absorb ing tube is 20. 5%, the quality of parts is nice and the forming of S shape transition region in a pair of mould can be fin ished.%针对防碰撞吸能管成形需要,提出了对铝合金6061圆管液压胀形过程的轴向进给补偿-液压力加载路径控制过程.通过数值模拟方法,采用分析软件ABAQUS 6.10对铝合金6061管材液压胀形的加载路径进行了研究.以成形件不发生起皱、破裂两种失效方式以及最终成形壁厚分布为依据,分析了不同轴向进给和液压力加载路径对成形件质量的影响.研究表明,采用轴向进给量为27mm,液压力为85 MPa的加载路径,获得吸能管的最大减薄率为20.5%,成形质量较好,并在一副模具中同时完成S型过渡区域的成形.

  1. Structural thermodynamics of alloys

    CERN Document Server

    Manenc, Jack

    1973-01-01

    Technical progress has for a very long time been directly dependent on progress in metallurgy, which is itself connected with improvements in the technology of alloys. Metals are most frequently used in the form of alloys for several reasons: the quantity of pure metal in its native state in the earth's crust is very limited; pure metals must be extracted from ores which are themselves impure. Finally, the methods of treatment used lead more easily to alloys than to pure metals. The most typical case is that of iron, where a pure ore may be found, but which is the starting point for cast iron or steel, alloys of iron and carbon. In addition, the properties of alloys are in general superior to those of pure metals and modem metallurgy consists of controlling these properties so as to make them conform to the requirements of the design office. Whilst the engineer was formerly compelled to adapt his designs and constructions to the materials available, such as wood, stone, bronze, iron, cast iron and ordinary st...

  2. Alloys of clathrate allotropes for rechargeable batteries

    Science.gov (United States)

    Chan, Candace K; Miller, Michael A; Chan, Kwai S

    2014-12-09

    The present disclosure is directed at an electrode for a battery wherein the electrode comprises clathrate alloys of silicon, germanium or tin. In method form, the present disclosure is directed at methods of forming clathrate alloys of silicon, germanium or tin which methods lead to the formation of empty cage structures suitable for use as electrodes in rechargeable type batteries.

  3. Effect of Bending Forming on Fatigue for A6N01 Aluminum Alloy%压弯成形对A6N01铝合金疲劳性能的影响

    Institute of Scientific and Technical Information of China (English)

    胡浩; 李晓星; 赵金泽; 乔雅智; 周超

    2014-01-01

    针对A6N01铝合金材料的压弯成形工艺,研究了压弯成形过程中等效塑性应变、残余应力、厚度减薄等参数的变化规律。基于原始材料和成形件疲劳试验数据,采用三参数幂函数形式进行数据处理,拟合得到S-N曲线。通过对比不同状态材料的疲劳寿命,探究压弯成形对该材料的疲劳寿命的影响。%According to bending forming process of A6N01 aluminum alloy, the rules of the equivalent plastic strain, residual stress and thickness thinning parameters were obtained by test and FEM. Based on the materials fatigue test data, the form of three parameters power function was used for processing data and fitting S-N curve. By comparing the different states of material fatigue life, the effect of bending forming on the fatigue life of the material was explored.

  4. Aluminum alloy

    Science.gov (United States)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  5. Influence of Y, Gd and Sm on the glass forming ability and thermal crystallization of aluminum based alloy; Efeito das terras raras Y, Gd e Sm na tendencia a formacao de amorfo e na cristalizacao termica em ligas a base de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta Filho, W.J., E-mail: aliaga@ufscar.b [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Danez, G.P. [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Al-based amorphous alloys represent an important family of metals and a great scientific activity has been devoted to determine the main features of both glass forming ability (GFA) and crystallization behavior in order to have a comprehensive framework aimed at potential technological applications. Nowadays, it is well known that the best Al-based amorphous alloys are formed in ternary systems such as Al- RE-TM, where RE is a rare earth and TM a transition metal. This paper presents results of research in Al{sub 85}Ni{sub 10}RE{sub 5} alloys (RE = Y, Gd and Sm). Amorphous ribbons were processed by melt-spinning under the same conditions and subsequently characterized by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results show appreciable micro structural differences as function of the rare earth, thus crystal is obtained for Y, nano-glassy for Gd and, fully amorphous structure for Sm. (author)

  6. Investigation of the formability of aluminium alloys at elevated temperatures

    Science.gov (United States)

    Tisza, M.; Budai, D.; Kovács, P. Z.; Lukács, Zs

    2016-11-01

    Aluminium alloys are more and more widely applied in car body manufacturing. Increasing the formability of aluminium alloys are one of the most relevant tasks in todays’ research topics. In this paper, the focus will be on the investigation of the formability of aluminium alloys concerning those material grades that are more widely applied in the automotive industry including the 5xxx and 6xxx aluminium alloy series. Recently, besides the cold forming of aluminium sheets the forming of aluminium alloys at elevated temperatures became a hot research topic, too. In our experimental investigations, we mostly examined the EN AW 5754 and EN AW 6082 aluminium alloys at elevated temperatures. We analysed the effect of various material and process parameters (e.g. temperature, sheet thickness) on the formability of aluminium alloys with particular emphasis on the Forming Limit Diagrams at elevated temperatures in order to find the optimum forming conditions for these alloys.

  7. Experimental Study on Laser Cutting Based on Removal Forms for Aluminum Alloy Sheet%基于去除熔化物形态分析的铝合金薄板激光切割试验研究

    Institute of Scientific and Technical Information of China (English)

    王彦飞; 王续跃; 康仁科; 徐文骥; 郭东明

    2012-01-01

    为提高铝合金薄板激光切割质量,对切割去除熔化物进行了收集、观察及测量研究.在Nd:YAG脉冲激光切割模式下,采用不同气熔比0.1898,0.2798,0.3708和0.6519,对0.85mm厚的1000系铝合金薄板进行切割试验.试验通过超景深三维显微镜对收集的去除熔化物形状和尺寸进行观测研究.结果表明,去除熔化物颗粒由球形颗粒和蝌蚪形颗粒两种颗粒组成,其中球形颗粒平均尺寸在71~123 μm之间;高气熔比切割去除熔化物主要呈球形,颗粒尺寸较小,切割质量较好:低气熔比下熔化物主要是蝌蚪形,其中呈现的球形颗粒尺寸较大,切割质量较差.试验最终在辅助气压0.6MPa高气熔比0.6519下获得了较高质量的切口.研究结果深化了铝合金激光切割的机理认识,有效提高了铝合金薄板的激光切割质量.%To improve the quality of laser cutting in aluminum alloy sheet, the collected melt is observed and measured. Laser cutting of 1000 series aluminum alloy sheets, with 0. 85mm thickness, is carried out on a Nd: YAG pulsed laser machine under the different vapor-melt ratios of 0.1898, 0.2798, 0.3708 and 0. 6519. In experiments the shape and size of collected removal are analyzed by a 3-D microscope. The melt is found to be tadpole-shape particles and spherical particles ranging of 71~123 μm in average diameter. The results show the collected particles are formed spherical at the high vapor-melt ratio and small in average diameter with good cutting quality. In contrast, at the low vapor-melt ratio the form is mainly tadpole-shape and the existence of big spherical particles of which with poor cutting quality. Finally, under the condition of gas pressure of 0. 6 MPa and high vapor-melt ratio of 0. 6519, the researches achieve higher quality cut. The results help researchers to understand the characteristics of laser cutting in aluminum alloy and improve the laser cutting quality of aluminum alloy sheet

  8. Modification of the titanium alloy surface in electroexplosive alloying with boron carbide and subsequent electron-beam treatment

    Science.gov (United States)

    Gromov, Victor E.; Budovskikh, Evgeniy A.; Ivanov, Yurii F.; Bashchenko, Lyudmila P.; Wang, Xinli; Kobzareva, Tatyana Yu.; Semin, Alexander P.

    2015-10-01

    The modification of the VT6 titanium alloy surface in electroexplosion alloying with plasma being formed in titanium foil with a weighed powder of boron carbide with subsequent irradiation by a pulsed electron beam has been carried out. An electroexplosive alloying zone of a thickness up to 50 μm with a gradient structure is found to form. The subsequent electron-beam treatment of the alloying zone results in smoothing of the alloying surface and is accompanied by the formation of the multilayer structure with alternating layers of various alloying degree at a depth of 30 μm.

  9. Modification of the titanium alloy surface in electroexplosive alloying with boron carbide and subsequent electron-beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Victor E., E-mail: gromov@physics.sibsiu.ru; Budovskikh, Evgeniy A., E-mail: budovskikh-ea@physics.sibsiu.ru; Bashchenko, Lyudmila P., E-mail: gromov@physics.sibsiu.ru; Kobzareva, Tatyana Yu., E-mail: gromov@physics.sibsiu.ru; Semin, Alexander P., E-mail: gromov@physics.sibsiu.ru [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Ivanov, Yurii F., E-mail: yufi55@mail.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Wang, Xinli, E-mail: wangxl520@hotmail.com [Northeastern University, Liaoning, Shenyang 110819 China (China)

    2015-10-27

    The modification of the VT6 titanium alloy surface in electroexplosion alloying with plasma being formed in titanium foil with a weighed powder of boron carbide with subsequent irradiation by a pulsed electron beam has been carried out. An electroexplosive alloying zone of a thickness up to 50 μm with a gradient structure is found to form. The subsequent electron-beam treatment of the alloying zone results in smoothing of the alloying surface and is accompanied by the formation of the multilayer structure with alternating layers of various alloying degree at a depth of 30 μm.

  10. Micro-Structures of Hard Coatings Deposited on Titanium Alloys by Laser Alloying Technique

    Science.gov (United States)

    Li, Wei; Yu, Huijun; Chen, Chuanzhong; Wang, Diangang; Weng, Fei

    2013-01-01

    This work is based on micro-structural performance of the Ti-B4C-C laser alloying coatings on Ti-6Al-4V titanium alloy. The test results indicated that laser alloying of the Ti-B4C-C pre-placed powders on the Ti-6Al-4V alloy substrate can form the ceramics reinforced hard alloying coatings, which increased the micro-hardness and wear resistance of substrate. The test result also indicated that the TiB phase was produced in alloying coating, which corresponded to its (101) crystal plane. In addition, yttria has a refining effect on micro-structures of the laser alloying coating, and its refinement mechanism was analyzed. This research provided essential experimental and theoretical basis to promote the applications of the laser alloying technique in manufacturing and repairing of the aerospace parts.

  11. 水蒸汽影响氧化铝膜生长的研究新进展%PROGRESS OF WATER VAPOUR EFFECT ON GROWTH OF ALUMINA FORMING ALLOYS

    Institute of Scientific and Technical Information of China (English)

    邢琳琳; 郑雁军; 崔立山; 孙茂虎; 邵明增; 卢贵武

    2011-01-01

    Alumina coating has excellent thermal stability at elevated temperatures, this can provide a good diffusion barrier to withstand high temperature oxidation and therefore, increase their life time in aggressive atmospheres. With the industrial development, water vapour is present in nearly all atmospheres where alumina forming alloys are used at high temperatures for industrial process. The most important problem is that how to maintain excellent performance of alloy in humid atmospheres. This paper summarizes the effect of water or water vapour on the stability of alumina scales, growth kinetics, film adherence and alumina film surface morphology.%氧化铝涂层是满足高温工业环境的最佳保护性氧化膜之一,能够有效保护钢材料在高温、强腐蚀环境下发生的腐蚀。随着工业的发展,水或者水蒸汽广泛存在于氧化铝膜的各类服役环境中,如何使氧化铝涂层在含水蒸汽的高温环境中保持优异的力学性能和寿命是工业中面临的一个重要的问题。本文综述了含水气氛对合金氧化铝的稳定性、生长动力学、膜的结合力和对氧化铝膜表面形貌的影响。

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

    Science.gov (United States)

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

    2016-05-03

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

  13. Superplastic forming of Ti6Al4V alloy using ZrO_2-TiO_2 ceramic die with adjustable linear thermal expansion coefficient

    Institute of Scientific and Technical Information of China (English)

    JIANG Shao-song; ZHANG Kai-feng

    2009-01-01

    Firstly, the relation between the coefficient of thermal expansion(CTE) and the volume fraction of TiO_2 was investigated, and also the influence of relative density of ceramic on the CTE was studied. The results show that the volume fraction, of TiO_2 and the relative density both make influence on the CTE of ZrO_2-TiO_2 ceramic. According to the results, the ZrO_2-TiO_2(volume fraction of TiO_2 is 27%) ceramic die with the similar CTE (8.92×10~(-6)℃~(-1)) to Ti6Al4V was fabricated. Secondly, to evaluate the dimensional accuracy of the workpiece superplastically formed, the Ti6Al4V impression experiment was performed. The result shows that the dimensional inaccuracy of workpieee is 0.003. Thirdly, in order to evaluate the practicability, the experiment of superplastic forming Ti6Al4V using ZrO_2-TiO_2 cylinder ceramic die was carried out. The Ti6Al4V cylinder shows good shape retention and surface quality, and high dimensional accuracy. The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V,and the trials have confirmed the potential of the ZrO2-TiO2 ceramic die.

  14. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  15. High strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  16. Dry sliding wear of Al-Fe-Cr-Mn quasicrystalline phase former alloy obtained by spray forming; Estudo do comportamento ao desgaste de liga Al-Fe-Cr-Mn obtida por conformacao por spray

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, S.M.T.; Rios, C.T.; Botta Filho, W.J.; Bolfarini, C.; Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Gargarella, P.; Mendes, M.A.B., E-mail: marcio.andreato@gmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Samples from different regions of a spray formed billet of Al{sub 92}Fe{sub 3}Cr{sub 2}Mn{sub 3} quasicrystalline phase former alloy were analyzed and their wear behavior has been studied. The microstructures observed depend on the cooling rate imposed to the material. The border of the billet exhibits a very fine structure with presence of quasicrystalline phase and the base showed a fine structure but without presence of quasicrystalline phase. Dry sliding wear tests were made using three loads and samples of these two different regions. The wear surfaces were analyzed by scanning electron microscopy and X-ray diffraction. Similar wear behavior was observed in the border and the base samples at the same load. The wear mechanism verified is the adhesive and the applied load increases the formation of Al{sub 2}O{sub 3}. These particles can take off the surface and act as abrasive, which can explain the large increase in the wear rate for the samples loaded at 30N.(author)

  17. 铝合金表面纳米化--微弧氧化复合涂层摩擦行为%Tribological behavior of SNC-MAO composite coatings formed on the surface of aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    文磊; 王亚明; 金莹

    2015-01-01

    通过表面机械研磨处理在LY12CZ铝合金表面制备表面纳米化( SNC)过渡层,再采用微弧氧化( MAO)技术对纳米晶过渡层进行微结构重构,设计制备出纳米化-微弧氧化( SNC-MAO)复合涂层,并对比研究了铝合金表面微弧氧化涂层及纳米化-微弧氧化复合涂层的摩擦学行为。与微弧氧化涂层相比,纳米化-微弧氧化复合涂层因硬度较高而具有较好的耐磨性。微弧氧化涂层及纳米化-微弧氧化复合涂层与GCr15钢球对磨时具有相同的磨损机理,为对磨钢球向涂层的材料转移和氧化磨损。%A duplex process was designed to modify the surface of LY12CZ aluminum alloy by using surface mechanical attrition treatment ( SMAT) prior to microarc oxidation ( MAO) . A surface nanocrystalline ( SNC) layer was formed on the alloy surface by SMAT, a ceramic outer layer grew on the SNC layer by MAO, and finally an SNC-MAO composite coating was fabricated. The tribo-logical behaviors of the MAO coating and SNC-MAO composite coating were comparatively evaluated. Experimental results showed that the SNC-MAO composite coating had a better wear resistance than the MAO coating in the same test condition due to a higher hardness of the ceramic coating. The wear mechanism of the MAO coating and SNC-MAO composite coating involved materials transfer from the steel ball to the coating and oxidation wear.

  18. Bonding theory for metals and alloys

    CERN Document Server

    Wang, Frederick E

    2005-01-01

    Bonding Theory for Metals and Alloys exhorts the potential existence of covalent bonding in metals and alloys. Through the recognition of the covalent bond in coexistence with the 'free' electron band, the book describes and demonstrates how the many experimental observations on metals and alloys can all be reconciled. Subsequently, it shows how the individual view of metals and alloys by physicists, chemists and metallurgists can be unified. The physical phenomena of metals and alloys covered in this book are: Miscibility Gap between two liquid metals; Phase Equilibrium Diagrams; Phenomenon of Melting. Superconductivity; Nitinol; A Metal-Alloy with Memory; Mechanical Properties; Liquid Metal Embrittlement; Superplasticity; Corrosion; The author introduces a new theory based on 'Covalon' conduction, which forms the basis for a new approach to the theory of superconductivity. This new approach not only explains the many observations made on the phenomenon of superconductivity but also makes predictions that ha...

  19. Modeling dissolution in aluminum alloys

    Science.gov (United States)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  20. The Formablity of AZ31B Magnesium Alloy Sheet

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; LU Zhiwen; ZHAO Yazhong; QIU Xiaogang

    2006-01-01

    The forming limit diagrams(FLD)of AZ31B magnesium alloy sheet were tested by means of the electro etching grid method based on the forming experiment of magnesium alloy sheet carried out with a BCS-30D sheet forming testing machine and the strain testing analysis made with an advanced ASAME automatic strain measuring system. Experiments show that, at room temperature, the mechanical properties and deep drawing performance of AZ31B cold-rolled magnesium alloy sheet were so poor that it failed to test the forming limit diagrams without an ideal forming and processing capacity, while the hot-rolled magnesium alloy sheet was of a little better plasticity and forming performance after testing its forming limit diagrams. It can be concluded that the testing of the forming limit curves (FLC)offers the theoretical foundation for the drawing of the deep drawing and forming process of magnesium alloy sheet.

  1. Dispersoid reinforced alloy powder and method of making

    Science.gov (United States)

    Anderson, Iver E.; Terpstra, Robert L.

    2010-04-20

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  2. Lubricant Test Methods for Sheet Metal Forming

    DEFF Research Database (Denmark)

    Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

    2008-01-01

    Sheet metal forming of tribologically difficult materials such as stainless steel, Al-alloys and Ti-alloys or forming in tribologically difficult operations like ironing, punching or deep drawing of thick plate requires often use of environmentally hazardous lubricants such as chlorinated paraffin...

  3. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...... means that form serves both as the connective value and as the concept for reflection. In other words, form is observed as form, not anything else. The didactical challenge of teaching form as form is accentuated by students’ everyday-based pre-orientation towards function at the expense of form....... In general, students enter design education as far more skilled observers with regards to function than form. They are, in other words, predisposed to observe objects asking ‘what is?’, rather than ‘how is?’. This habit has not only cognitive implications. It is closely intertwined with a rudimentary...

  4. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  5. Casting Characteristics of Aluminum Die Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  6. Diffusion Barrier Coating System and Oxidation Behavior of Coated Alloys

    Institute of Scientific and Technical Information of China (English)

    T.NARITA

    2009-01-01

    @@ 1 Introduction Research into the formation of Re-based alloys is in progress in our laboratory to provide a diffusion barrier layer between heat-resistant alloys and Al reservoir layers, which assist in the formation and maintenance a protective Al2O3 scale for long periods. Coatings with a two-layered structure comprised of inner Re-based alloy layer and outer β-NiAl layer with or without Pt addition were successfully formed on various heat resistant alloys such as Ni-based singlecrystal superalloys, Ni-based heat resistant alloys, NiMo based alloy, Ni-Cr based alloy, and Fe-based alloys. The duplex layer coating proposed is generally termed a diffusion barrier coating system; DBC system.

  7. Wear resistant steels and casting alloys containing niobium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Theisen, W.; Siebert, S.; Huth, S. [Lehrstuhl Werkstofftechnik, Ruhr-Univ. Bochum (Germany)

    2007-12-15

    Niobium, like titanium and vanadium, forms superhard MC carbides that remain relatively pure in technical alloys on account of their low solubility for other metallic alloying elements. However, because they have a greater hardness than the precipitated chromium carbides commonly used in wear-resistant alloys, they are suitable as alternative hard phases. This contribution deals with new wear-resistant steels and casting alloys containing niobium carbide. These include a secondary hardening hardfacing alloy, a composite casting alloy for wear applications at elevated temperatures, a white cast iron as well as two variants of a corrosion-resistant cold-work tool steel produced by melt metallurgy and by powder metallurgy. A heat-resistant casting alloy is also discussed. Based on equilibrium calculations the microstructures developing during production of the alloys are analysed, and the results are discussed with respect to important properties such as abrasive wear and corrosion resistance. (orig.)

  8. Oligocrystalline shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ueland, Stian M.; Chen, Ying; Schuh, Christopher A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2012-05-23

    Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture arising from transformation strain incompatibility at grain boundaries and triple junctions. Oligocrystalline shape memory alloys (oSMAs) are microstructurally designed SMA structures in which the total surface area exceeds the total grain boundary area, and triple junctions can even be completely absent. Here it is shown how an oligocrystalline structure provides a means of achieving single crystal-like SMA properties without being limited by constraints of single crystal processing. Additionally, the formation of oSMAs typically involves the reduction of the size scale of specimens, and sample size effects begin to emerge. Recent findings on a size effect on the martensitic transformation in oSMAs are compared and a new regime of heat transfer associated with the transformation heat evolution in these alloys is discussed. New results on unassisted two-way shape memory and the effect of loading rate in oSMAs are also reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Study on selective laser melting process and forming of AlSi10 Mg alloy powder%选择性激光熔化AlSi10 Mg合金粉末的成形工艺

    Institute of Scientific and Technical Information of China (English)

    刘锦辉; 史金光; 李亚

    2015-01-01

    This paper deals with the single-layer single-channel experiment and single-layer multi-channel experiment performed by using different process parameters to study the selective laser melting (SLM) forming process of AlSi10Mg alloy powder. This study consists of analyzing the effects of laser power, laser scanning speed, scanning interval on melting channel width and surface quality;testing the density of SLM AlSi10 Mg samples formed under different parameters and analyzing the relationship be-tween energy density and the sample density; and testing the microstructure and property, and micro-hardness. The results show that the optimal scanning track quality is governed the given process parame-ters:laser power between 240~280 W, scanning speed between 1 000~1 400 mm/s, scanning interval between 0 . 06~0 . 08 mm; SLM-produced AlSi10 Mg parts perform much better than conventionally cast AlSi10 Mg ones .%为了研究AlSi10 Mg合金粉末的选择性激光熔化成形,采用不同的工艺参数,进行了单层单道扫描实验和单层多道扫描实验。分析激光功率、激光扫描速度、扫描间距对激光扫描轨迹宽度和表面质量的影响。检测不同参数下选择性激光熔化成形的AlSi10 Mg合金块的致密度,分析成形件致密度与能量密度的关系,成形件的组织和性能,对成形件进行硬度测试。结果表明:激光功率在240~280 W,扫描速度在1000~1400 mm/s,扫描间距在0.06~0.08 mm时,扫描轨迹成形质量最佳。与传统铸造AlSi10Mg合金零件相比,SLM成形的零件具有更好的性能。

  10. Measurement of oxide adherence to PFM alloys.

    Science.gov (United States)

    Mackert, J R; Parry, E E; Hashinger, D T; Fairhurst, C W

    1984-11-01

    A method has been reported for evaluating adherence of an oxide to its substrate metal to a maximum value of about 40 MPa. Oxidized alloy plates were cemented between two aluminum cylinders with a high-strength cyanoacrylate cement and loaded in tension until failure occurred either at the oxide/metal interface, within the oxide layer, or in the cement itself. Significant differences were found among the oxide adherence values obtained from different PFM alloys. The oxides formed on five of the alloys exhibited adherence strengths in excess of the published value for cohesive strength of dental opaque porcelain, indicating that they possess sufficient adherence to act as the transition zone between the porcelain and the alloy. In addition, a correspondence was found between the quality of porcelain bond for a given alloy and its oxide adherence strength. These results remove the principal objection to the oxide-layer theory of porcelain bonding in dental alloy systems and emphasize the importance of oxide adherence in the establishment of a bond. It is therefore suggested that future work devoted to porcelain-metal bonding should seek to elucidate the mechanism of oxide adherence to PFM alloys and explore the development of new alloys which form adherent oxides.

  11. HAYNES 244 alloy – a new 760 ∘C capable low thermal expansion alloy

    Directory of Open Access Journals (Sweden)

    Fahrmann Michael G.

    2014-01-01

    Full Text Available HAYNES® 244TM alloy is a new 760∘C capable, high strength low thermal expansion (CTE alloy. Its nominal chemical composition in weight percent is Ni – 8 Cr – 22.5 Mo – 6 W. Recently, a first mill-scale heat of 244 alloy was melted by Haynes International, and processed to various product forms such as re-forge billet, plate, and sheet. This paper presents key attributes of this new alloy (CTE, strength, low-cycle fatigue performance, oxidation resistance, thermal stability as they pertain to the intended use in rings and seals of advanced gas turbines.

  12. New Stainless Steel Alloys for Low Temperature Surface Hardening?

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2015-01-01

    The present contribution showcases the possibility for developing new surface hardenable stainless steels containing strong nitride/carbide forming elements (SNCFE). Nitriding of the commercial alloys, austenitic A286, and ferritic AISI 409 illustrates the beneficial effect of having SNCFE present...... in the stainless steel alloys. The presented computational approach for alloy design enables “screening” of hundreds of thousands hypothetical alloy systems by use of Thermo-Calc. Promising compositions for new stainless steel alloys can be selected based on imposed criteria, i.e. facilitating easy selection...

  13. Long - range foundry Al composite alloys

    Directory of Open Access Journals (Sweden)

    A. D. Mekhtiev

    2014-10-01

    Full Text Available The technology of obtaining nanostructural composite aluminum alloys consists in the plasma injection of refractory nanometric particles with simultaneous two-plane magnetic dynamic mixing of the melt. Particularly important in obtaining composite aluminum matrix alloys is the provision of the introduced particles wettability with the matrix melt for forming stable adhesive bonds. Nanostructured powder components can be considered not only to be a starting product for producing nanostructural composite aluminum alloys but as an independent commerce product. Nanostructural composite metal matrix alloys make one of the most prospective structural materials of the future, and liquid-phase technologies of their obtaining are the most competitive in producing products of nanostructural composite aluminum alloys in the industrial scale.

  14. Oxidation of Alloy 600 and Alloy 690: Experimentally Accelerated Study in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Cao, Guoping; Was, Gary S.

    2017-02-01

    The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe2O4 formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr2O3 at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr2O3 layer at the surface, preventing grain boundary oxidation from occurring.

  15. Oxidation of Alloy 600 and Alloy 690: Experimentally Accelerated Study in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Cao, Guoping; Was, Gary S.

    2017-04-01

    The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe2O4 formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr2O3 at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr2O3 layer at the surface, preventing grain boundary oxidation from occurring.

  16. Minor alloying behavior in bulk metallic glasses and high-entropy alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of minor alloying on several bulk metallic glasses and high-entropy al-loys was studied. It was found that minor Nb addition can optimize the interface structure between the W fiber and the Zr-based bulk metallic glass in the compos-ites,and improve the mechanical properties. Minor Y addition can destabilize the crystalline phases by inducing lattice distortion as a result to improve the glass-forming ability,and the lattice distortion energy is closely related to the effi-ciency of space filling of the competing crystalline phases. A long-period ordered structure can precipitate in the Mg-based bulk metallic glass by yttrium alloying. For the high-entropy alloys,solid solution can be formed by alloying,and its me-chanical properties can be comparable to most of the bulk metallic glasses.

  17. Precision forging technologies for magnesium alloy bracket and wheel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fundamental investigations on precision forging technology of magnesium alloys were studied. As-cast billet prestraining and a new concept of hollow billet were proposed in order to reduce the maximum forming load. A scheme of isothermal forming and the use of combined female dies were adopted, which can improve the die filling capacity and ensure the manufacture of high quality forgings. By means of the developed technique, AZ80 alloy wheel and AZ31 alloy bracket were produced successfully at suitable process parameters and applied in the automotive industries. The results show that the hot compression of AZ80 magnesium alloy has the peak flow stresses of pre-strained alloy with finer grain, which are lower by 20% than those of as-cast alloy under the same deformation conditions. The forming load is related to contact area and average positive stress on interface during forging process.

  18. Microstructure and properties of modified and conventional 718 alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Fang; SUN Wen-ru; DU Jin-hui; DONG Jian-xin; GUO Shou-ren; YANG Hong-cai; HU Zhuang-qi

    2006-01-01

    Continuing the effort to redesign IN718 alloy in order to provide microstructural and mechanical stability beyond 650 ℃, IN718 alloy was modified by increasing the Al, P and B contents, and the microstructure and mechanical properties of the modified alloy were compared with those of the conventional alloy by SEM and TEM. The precipitation of the grain boundaries of the two alloys is different. The Cr-rich phase, Laves phase and α-Cr phase are easily observed in the modified alloy. The γ″ and γ′ phases in the modified alloy are precipitated in a "compact form". The tensile strengths of the modified alloy at room temperature and 680 ℃ are obviously higher than those of the conventional one. The impact energy of the modified alloy is only about half of that of the conventional alloy. Ageing at 680 ℃ up to 1 000 h lowers the tensile properties and impact energy of both the conventional and modified 718 alloys, except increasing the ductility at 680 ℃. It is concluded that the modified alloy is more stable than the conventional one.

  19. Miniature High Force, Long Stroke Linear Shape Memory Alloy Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Memory Alloys (SMAs) are metal alloys (Nickel-Titanium, for example) that change shape when heated. When drawn and processed in wire form, the shape change is...

  20. Miniature High Force, Long Stroke Linear Shape Memory Alloy Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Memory Alloys (SMAs) are metal alloys (of Nickel-Titanium, for example) that can change their shape when heated. When drawn and processed in wire form, the...

  1. Microstructural and magnetic behavior of an equiatomic NiCoAlFe alloy prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Esparza, C.D.; Baldenebro-López, F.J.; Santillán-Rodríguez, C.R.; Estrada-Guel, I.; Matutes-Aquino, J.A.; Herrera-Ramírez, J.M., E-mail: martin.herrera@cimav.edu.mx; Martínez-Sánchez, R.

    2014-12-05

    Highlights: • Equiatomic NiCoAlFe powder alloys were synthesized by mechanical alloying. • The nanocrystalline alloys were characterized after milled and annealed conditions. • In alloyed and annealed powders, only BCC and FCC structure phases were observed. • Magnetic properties are strongly affected by the phases formed after annealing. - Abstract: Equiatomic NiCoAlFe powder alloys were synthesized by mechanical alloying. The microstructural evolution of the mechanically alloyed powders at different times was followed with X-ray diffraction and scanning electron microscopy. The as-mechanically alloyed powders were subjected to a rapid annealing treatment at 1273 K and 1473 K during 3 min in vacuum. X-ray diffraction studies show the structure of both, the as-mechanically alloyed and annealed powders, consisted in a mixture of nanocrystalline simple phases (FCC + BCC). Crystallite size, after annealing, still remained in nanoscale. Coercivity increased due to the decrease in crystallite size and because of the defects caused by mechanical alloying in the as-mechanically alloyed samples; then coercivity decreased due to the phenomenon of random magnetic anisotropy and tended to stabilize with longer alloying times. A similar behavior was observed in annealed samples at 1273 K. However, random magnetic anisotropy was not observed after annealing at 1473 K because crystals with larger sizes were produced, and a steady increase in coercivity was observed.

  2. Microstructures and Mechanism of Cracks Forming of Rene 80 High-Temperature Alloy Fabricated by Laser Rapid Forming Process%激光快速成形Rene80高温合金组织及裂纹形成机理

    Institute of Scientific and Technical Information of China (English)

    席明哲; 高士友

    2012-01-01

    研究了激光快速成形(LRF)Rene 80高温合金厚壁件的凝固组织和裂纹的形成机理.结果表明,激光快速成形Rene 80高温合金的凝固组织为与沉积高度方向平行的定向凝固枝晶组织,由于凝固偏析,MC型碳化物和γ-γ′共晶组织分布于定向凝固组织的枝晶间区域.激光快速成形Rene 80高温合金厚壁件含有许多长度大于10 mm,扩展方向与沉积高度方向平行的宏观裂纹.分析表明,这些裂纹为液化裂纹,其形成原因为:激光快速成形时,紧邻激光熔池的热影响区(HAZ)内沿晶界分布的低熔点γ-γ′共晶组织发生熔化,形成热影响区内沿晶界扩展的晶界液相,在热影响区冷却过程中,由于热影响区内固相的收缩应力作用,沿晶界扩展的固-液界面被撕开,从而导致液化裂纹的产生.%The microstructures and mechanism, of cracks forming of a thick-wall part of Rene 80 superalloy fabricated by laser rapid forming (LRF) process are presented. Results show that the solidified microstructures of LRF Rene 80 high-temperature alloy consist of directionally solidified dendrites, which are parallel with the deposition direction. The MC type carbides and γ — γ' eutectic distribute in interdendritic region of the directionally solidified microstructure due to element segregation. The LRF Rene 80 high-temperature alloy thick-wall part contains many macro cracks, which have the length of more than 10 mm and expand along the direction parallel to the deposition direction. Analyses indicate that these macro cracks are liquated cracks. During LRF process, the γ—γ' eutectic with lower melting point particularly along the grain-boundary regions in heat-affected zone (HAZ) melt produced by laser melting pool and result in the formation of grain-boundary liquid. On the subsequent cooling process of the HAZ, the liquated cracks along the HAZ grain boundaries occurred by decohesion across the liquid-solid interface due to

  3. 钛合金筋板件等温局部加载模具应力分析%Stress analysis of die for Ti-alloy rib-web component isothermal local loading forming

    Institute of Scientific and Technical Information of China (English)

    暴志峰; 孙志超; 杨合

    2009-01-01

    等温局部加载成形技术为航空航天复杂筋板类大型整体构件的成形提供了一种新的途径,但由于构件尺寸大,其成形温度高、时间长、载荷大等工艺特点,对模具提出了更高的要求.文章针对TA15钛合金典型环形高筋薄腹特征结构件等温局部加载成形,分析了等温局部加载模具的结构特点和可能的失效形式,并在此基础上采用DEFORM 3D有限元软件,对成形时模具应力进行了研究,获得了模具载荷和应力分布规律,并进一步分析了模具凹圆角半径和锻件筋条宽度对模具应力的影响.结果表明,等温局部加载成形模具的失效形式,主要为应力集中引起的脆性断裂;加载分区边界附近模具应力较小,离分区边界越远模具应力越大,且应力峰值出现在宽度较小的环形筋型腔凹角处;模具型腔各部分材料填允能力的不一致,是导致模具应力不均匀、局部出现应力集中的主要原因;增大模具凹圆角半径,模具应力降低程度较小,而通过合理的锻件几何尺寸设计,可以改善模具型腔的充填性,能更有效地降低模具应力的不均匀性和应力峰值.文章的研究结果可为等温局部加载成形模具的设计提供参考.%Isothermal local loading forming provides a new approach to form large-scale integral rib-web complex component which are widely used in aerospace industry, while the higher requirement of die strength is needed due to the large dimension of component, high forming temperature, large forming load, and long forming time in the process. Aiming at rib-web annular component of TA15 titanium alloy isothermal local loading process, die structure characteristic and failure mode are analyzed. Die stress was studied by using finite element method based on DEFORM 3D platform. Load and stress distributions of die were obtained. The influences of the die fillet radius and width of rib on die stress were investigated farther. The

  4. Solid solution lithium alloy cermet anodes

    Science.gov (United States)

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  5. Titanium Alloys and Processing for High Speed Aircraft

    Science.gov (United States)

    Brewer, William D.; Bird, R. Keith; Wallace, Terryl A.

    1996-01-01

    Commercially available titanium alloys as well as emerging titanium alloys with limited or no production experience are being considered for a variety of applications to high speed commercial aircraft structures. A number of government and industry programs are underway to improve the performance of promising alloys by chemistry and/or processing modifications and to identify appropriate alloys and processes for specific aircraft structural applications. This paper discusses some of the results on the effects of heat treatment, service temperatures from - 54 C to +177 C, and selected processing on the mechanical properties of several candidate beta and alpha-beta titanium alloys. Included are beta alloys Timetal 21S, LCB, Beta C, Beta CEZ, and Ti-10-2-3 and alpha-beta alloys Ti-62222, Ti-6242S, Timetal 550, Ti-62S, SP-700, and Corona-X. The emphasis is on properties of rolled sheet product form and on the superplastic properties and processing of the materials.

  6. 连续ECAE 动态时效成形制备Al-Zr-B 合金的组织与性能%Microstructures and Properties of Al-Zr-B Alloy Wires Prepared by Continuous Dynamic Aging ECAE Forming

    Institute of Scientific and Technical Information of China (English)

    周天国; 张安; 石舟; 张哲; 张方方

    2016-01-01

    为制备高性能铝锆耐热合金导体,首次采用 ECAE 动态时效成形工艺制备了 Al-Zr-B 合金导体.借助光学显微镜、材料拉伸试验机和双臂直流电桥等测试手段,研究了连续 ECAE动态时效成形 Al-Zr-B合金显微组织、力学性能和导电性能.结果表明:随着 ECAE 成形道次的增加,合金线材的组织逐渐趋于均匀;时效热处理可有效改善 Al-Zr-B合金导线的力学性能和导电性能.随着时效时间的延长,合金的抗拉强度先升高,出现峰值强度,再延长时效时间,强度降低;伸长率随着时间延长一直降低,等效导电率则不断升高.当时效温度180℃、时效时间12 h时,Al-0.3Zr-0.06B合金的拉伸强度为265.32 MPa、伸长率为6.7%、等效导电率为59.54%IACS,Al-Zr耐热合金导线的综合性能较好.%In order to prepare high performance aluminum zirconium heat-resistant conductor,Al-Zr-B alloy conductor was prepared by continuous dynamic aging ECAE (Equal Channel Angular Extrusion) process.By means of OM,electronic tensile machine and double arm direct current bridge,the microstructure, mechanical properties and electrical properties of Al-Zr-B alloy prepared by continuous dynamic aging ECAE process were studied.The result shows that the microstructure of the alloy wires become homogeneous gradually with the increase of the ECAE forming passes;the mechanical and electrical properties of Al-Zr-B alloy wire can be effectively improved by using artificial aging treatment.The tensile strength of the alloy increases with the aging time prolonged firstly, when rises to the peak strength,after that the strength decreases with the aging time further prolong;the elongation of the alloy decreases all the time;however,the equivalent conductivity increases. When the alloys soaked 180 ℃ for 12 h,the Al-Zr-B heat-resistant alloy wire has better complicated property,its tensile strength,elongation and the equivalent conductivity of the alloy is 265

  7. Solid metal induced embrittlement of titanium alloys

    OpenAIRE

    Åkerfeldt, Pia

    2012-01-01

    Titanium alloys were for a time believed to be highly resistant to environmentally assisted cracking because of their ability to form a protective oxide film on the surface. Their resistance can still be considered to be high, but when cracking resistance was originally defined to ensure reliable functionality of fracture-critical components, certain conditions that promote cracking were discovered. One of the environmental assisted cracking processes relevant to titanium alloys is solid meta...

  8. Internal gettering by metal alloy clusters

    Science.gov (United States)

    Buonassisi, Anthony; Heuer, Matthias; Istratov, Andrei A.; Pickett, Matthew D.; Marcus, Mathew A.; Weber, Eicke R.

    2010-07-27

    The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.

  9. Self-Organized Growth of Alloy Superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Chason, E.; Floro, J.A.; Follstaedt, D.M.; Lagally, M.G.; Liu, F.; Tersoff, J.; Venezuela, P.

    1998-10-19

    We predict theoretically and demonstrate experimentally the spontaneous formation of a superlattice during crystal growth. When a strained alloy grows by "step flow", the steps at the surface form periodic bunches. The resulting modulated strain biases the incorporation of the respective alloy components at different steps in the bunch, leading to the formation of a superlattice. X-ray diffraction and electron microscopy for SiGe grown on Si give clear evidence for such spontaneous superlattice formation.

  10. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    . Traditionally, theorem provers are used to prove that specifications are correct but this process is highly dependent on expert users. Alternatively, model finding has proved to be useful for validation of specifications. The Alloy Analyzer is an automated model finder for checking and visualising Alloy...... specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  11. Intermetallic alloy welding wires and method for fabricating the same

    Science.gov (United States)

    Santella, M.L.; Sikka, V.K.

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  12. Alloy Fabrication Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL’s Alloy Fabrication Facility in Albany, OR, researchers conduct DOE research projects to produce new alloys suited to a variety of applications, from gas...

  13. Microstructural Investigations of Rapidly Solidified Al-Co-Y Alloys

    OpenAIRE

    B. Avar; Gogebakan, M.; Tarakci, M.; Y. Gencer; S. Kerli

    2013-01-01

    The alloys with different compositions in the Al-rich corner of the Al-Co-Y ternary system were prepared by conventional casting and further processed by melt-spinning technique. The microstructure and the thermal behavior of the alloys were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). It was found that only rapidly solidified Al85Co7Y8 alloy exhibited the best glass forming ...

  14. Comparison of Metal Dusting Behavior of Several Alloys

    Institute of Scientific and Technical Information of China (English)

    HAN Guang-wei; DENG Bo; FENG Di

    2004-01-01

    Metal dusting behaviors of several alloys with different chromium contents and other elements were investigated in a given gaseous environment. The samples of the alloys were exposed at 650 ℃ for 650 h, and were periodically removed to examine coke protrusions and pits formed on the sample surfaces by SEM and determine metal wastage. The results were interpreted in terms of the compositional variations of the employed alloys.

  15. PRODUCTION OF FeAl NANOSTRUCTURED ALLOY BY MECHANICAL ALLOYING AND ITS MICROSTRUCTURAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Roberto. A. Rodríguez-Díaz

    2013-12-01

    Full Text Available In this work, a Fe40Al alloy was produced by the mechanical alloying technique, from a mixture of elemental powders constituted by Fe and Al, using different milling times. The evolution of size and morphology of powders depending on the milling time was characterized by scanning electron microscopy. The X-Ray Diffraction technique was utilized in order to characterize the crystalline structure evolution depending on the milling time. The Fe40Al alloy with a body centered cubic crystal structure was formed at 20 h of milling time. Besides, this alloy acquired a disordered crystal structure with a Nano metric grain size. The Nano metric grain size of disordered Fe40Al alloy was decreased at the same time as the milling time transcurred, while its lattice parameter was increased.

  16. Method for producing La/Ce/MM/Y base alloys, resulting alloys and battery electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

    2016-12-20

    A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels, cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.

  17. Collaborative form(s)

    DEFF Research Database (Denmark)

    Gunn, Wendy

    Gunn asks us to consider beauty as collaborative forms of action generated by moving between design by means of anthropology and anthropology by means of design. Specifically, she gives focus to play-like reflexions on practices of designing energy products, systems and infrastructure. Design...

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

    OpenAIRE

    Gammaitoni, Loïc; Kelsen, Pierre

    2015-01-01

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

  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. AZ91D镁合金表面不同树脂体系富镁涂层的保护性能%Protection performance of Mg-rich coatings formed by different epoxy resins on AZ91D alloys

    Institute of Scientific and Technical Information of China (English)

    卢向雨; 吴静英; 左禹; 郑传波

    2015-01-01

    采用划叉浸泡实验,电化学交流阻抗(electrochemical impedance spectroscopy,EIS),开路电位(open circuit potential,OCP)及动电位扫描研究了不同类型的环氧树脂对于AZ91D镁合金的表面的富镁涂层的保护性能的影响。结果表明环氧618-593构成的富镁涂层防护性能较差;环氧6101-TY650制备的富镁涂层可明显改善涂层对破损处镁合金基体的保护作用,但涂层本身长期防护性能较差;环氧618-T31构成的富镁涂层对AZ91D镁合金的防护作用较强,适宜制备镁合金表面的富镁涂层。3种环氧涂料中加入镁粉颗粒制备的富镁涂层均可对缺陷处裸露的 AZ91D 镁合金基体提供保护,从而延长漆膜的破坏时间。涂层中的镁粉颗粒被激活后,为镁合金的基体提供了一定程度的阴极保护作用,减缓了镁合金基体的腐蚀。%The influence of different types of epoxy resins on protection performance of magnesium-rich coating for AZ91D alloy was studied with scratch testing, electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and dynamic potential scanning. The results indicated that Mg-rich coating consisting of epoxy coating 618-593 showed poor protective performance. Magnesium particles in 6101-TY650 epoxy coating could significantly improve the protective effect for magnesium alloy substrate at the coating defects, however, their over the long-term protection performance was poor. Epoxy 618-T31 coating showed strong barrier properties. Then, the Mg-rich primer consisting of epoxy coating 618-T31 had a strong protective effect, indicating that the epoxy coating 618-T31 was suitable for the preparation of Mg-rich coating for AZ91D alloy. For AZ91D alloy, magnesium particles added in three types of epoxy coatings could provide cathodic protection to AZ91D substrate at coatings defects, prolonging the corrosion life of coatings. Meanwhile, magnesium particles were activated to

  1. Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

    Directory of Open Access Journals (Sweden)

    Chen Dongfeng

    2010-02-01

    Full Text Available AZ91D surface alloying was investigated through evaporative pattern casting (EPC technology. Aluminum powder (0.074 to 0.104 mm was used as the alloying element in the experiment. An alloying coating with excellent properties was fabricated, which mainly consisted of adhesive, co-solvent, suspending agent and other ingredients according to desired proportion. Mg-alloy melt was poured under certain temperature and the degree of negative pressure. The microstructure of the surface layer was examined by means of scanning electron microscopy. It has been found that a large volume fraction of network new phases were formed on the Mg-alloy surface, the thickness of the alloying surface layer increased with the alloying coating increasing from 0.3 mm to 0.5 mm, and the microstructure became compact. Energy dispersive X-ray (EDX analysis was used to determine the chemical composition of the new phases. It showed that the new phases mainly consist of β-Mg17Al12, in addition to a small quantity of inter-metallic compounds and oxides. A micro-hardness test and a corrosion experiment to simulate the effect of sea water were performed. The result indicated that the highest micro-hardness of the surface reaches three times that of the matrix. The corrosion rate of alloying samples declines to about a fifth of that of the as-cast AZ91D specimen.

  2. Effect of Nb Doping on High Temperature Oxidation Resistance of Ti-Al Alloyed Coatings

    Directory of Open Access Journals (Sweden)

    DAI Jing-jie

    2017-02-01

    Full Text Available Ti-Al alloyed coatings with different Nb doping contents were fabricated on TC4 titanium alloy by laser surface alloying to improve high temperature oxidation resistance of the alloy. Structures and high temperature oxidation behaviors of the alloyed coatings were analyzed and tested by X-ray diffraction (XRD, scanning electron microscope (SEM, energy dispersive spectrometer (EDS and box-type resistance furnace. The results show that the alloyed coatings consist of TiAl and Ti3Al, and no niobium compound are formed in Ti-Al-Nb alloyed coatings. The alloyed coatings are uniform and exhibit excellent metallurgical bonding with the substrates. A large amount of surface cracks and a few penetrating cracks are formed in Ti-Al alloyed coating without Nb doping, while no obvious cracks are formed in Ti-Al alloyed coating with Nb doping. The oxidation mass gains of all the alloyed coatings were significantly lower than those of the substrate. The alloyed coatings with Nb doping exhibit more excellent high temperature oxidation resistance due to the beneficial machanism of Nb doping. The mechanism of Nb doping on improving high temperature oxidation resistance of Ti-Al alloyed coatings includes reducing the defect concentration of TiO2, refining oxide grains and promoting the formation of Al2O3.

  3. NiAl alloys for structural uses

    Science.gov (United States)

    Koss, D. A.

    1991-01-01

    Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the

  4. Simulation of nuclei morphologies for binary alloy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

  5. Room temperature creep in metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deibler, Lisa Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Characterization and Performance

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  6. Influences of Yttrium on Cyclic Oxidation Behavior of Fe-Cr-Al Alloy

    Institute of Scientific and Technical Information of China (English)

    辛丽; 李美栓; 钱余海; 李铁藩

    2001-01-01

    The 1100 ℃ cyclic oxidation behavior of Fe-23Cr-5Al alloy modified by yttrium was studied. Yttrium was added to this alloy in the form of (1) metallic addition, (2) yttrium oxide dispersion and (3) ion implantation. Cracking and spalling occurred on the convoluted scale formed on Y-free alloy and the substrate was exposed. A flat dense scale without spallation was formed on the yttrium alloying addition or yttrium oxide dispersion alloy. Spallation mainly occurred between two layers of the scale on the 1×1017Y ions/cm2-implanted alloy. The results indicate the main reason that the adhesion of alumina scale was improved by yttrium addition lies in that yttrium is liable to form a stable yttrium sulfide with sulfur in the alloy and prevent sulfur interface segregation. Another reason is that the growth mechanism of alumina scale was changed by yttrium addition.

  7. Trials to manufacture and test castings from Inconel alloy

    Directory of Open Access Journals (Sweden)

    W. Uhl

    2010-07-01

    Full Text Available The article describes the methods of producing and testing the Inconel 740 nickel alloy in as-cast state. An assumption has been made that the obtained alloy should be characterised by a normative chemical composition and mechanical properties similar to those that are obtained in the process of plastic forming. The alloy was fabricated by conventional process and vacuum metallurgy in the form of pilot castings enabling various types of tests to be carried out. Within the test and investigations programme, moulding materials were chosen, castings were poured and subjected to the process of heat treatment, followed by tests and examinations of alloy properties (mechanical tests, cooling curves. The outcome of the investigations was cast alloy characterised by chemical composition close to the normative one but of the mechanical properties inferior to those obtained by plastic forming.

  8. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  9. High strength alloys

    Science.gov (United States)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  10. Tin-Silver Alloys for Flip-Chip Bonding Studied with a Rotating Cylinder Electrode

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Pedersen, E.H.; Bech-Nielsen, G.;

    1999-01-01

    Electrodeposition of solder for flip-chip bonding is studied in the form of a pyrophosphate/iodide tin-silver alloy bath. The objective is to obtain a uniform alloy composition, with 3.8 At.% silver, over a larger area. This specific alloy will provide an eutectic solder melting at 221°C (or 10°C...

  11. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  12. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  13. Magnetic structures of holmium-lutetium alloys and superlattices

    DEFF Research Database (Denmark)

    Swaddling, P.P.; Cowley, R.A.; Ward, R.C.C.;

    1996-01-01

    Alloys and superlattices of Ho and Lu have been grown using molecular beam epitaxy and their magnetic structures determined using neutron-scattering techniques. The 4f moments in the alloys form a helix at all compositions with the moments aligned in the basal plane perpendicular to the wave vector...

  14. Research progress of aluminum alloy automotive sheet and application technology

    Institute of Scientific and Technical Information of China (English)

    Ma Mingtu; You Jianghai; Lu Hongzhou; Wang Zhiwen

    2012-01-01

    Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author's knowledge and recognition and research progress presently, the important re- search contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.

  15. 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.

  16. A System of Test Methods for Sheet Metal Forming Tribology

    DEFF Research Database (Denmark)

    Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

    2007-01-01

    Sheet metal forming of tribologically difficult materials such as stainless steel, Al-alloys and Ti-alloys or forming in tribologically difficult operations like ironing, punching or deep drawing of thick plate requires often use of environmentally hazardous lubricants such as chlorinated paraffin...

  17. Trace Carbon in Biomedical Beta-Titanium Alloys: Recent Progress

    Science.gov (United States)

    Zhao, D.; Ebel, T.; Yan, M.; Qian, M.

    2015-08-01

    Owing to their relatively low Young's modulus, high strength, good resistance to corrosion, and excellent biocompatibility, β-titanium (Ti) alloys have shown great potential for biomedical applications. In β-Ti alloys, carbon can exist in the form of titanium carbide (TiC x ) as well as interstitial atoms. The Ti-C binary phase diagram predicts a carbon solubility value of 0.08 wt.% in β-Ti, which has been used as the carbon limit for a variety of β-Ti alloys. However, noticeable grain boundary TiC x particles have been observed in β-Ti alloys containing impurity levels of carbon well below the predicted 0.08 wt.%. This review focuses its attention on trace carbon (≤0.08 wt.%) in biomedical β-Ti alloys containing niobium (Nb) and molybdenum (Mo), and it discusses the nature and precipitation mechanism of the TiC x particles in these alloys.

  18. Bulk Glassy Alloys: Historical Development and Current Research

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2015-06-01

    Full Text Available This paper reviews the development of current research in bulk glassy alloys by focusing on the trigger point for the synthesis of the first bulk glassy alloys by the conventional mold casting method. This review covers the background, discovery, characteristics, and applications of bulk glassy alloys, as well as recent topics regarding them. Applications of bulk glassy alloys have been expanding, particularly for Fe-based bulk glassy alloys, due to their unique properties, high glass-forming ability, and low cost. In the near future, the engineering importance of bulk glassy alloys is expected to increase steadily, and continuous interest in these novel metallic materials for basic science research is anticipated.

  19. Rolling and Forming of Thorium Metal

    Energy Technology Data Exchange (ETDEWEB)

    Calabra, A. E.

    1961-05-02

    One vacuum induction melted and cast nuclear grade thorium ingot was satisfactorily rolled and formed into a hemispherical shape. Attempts to roll and form two vacuum induction melted and cast alloy grade thorium ingots were not successful. Rolling and forming procedures are described and metallurgical evaluation is reported.

  20. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  1. High-Strength Low-Alloy (HSLA) Mg-Zn-Ca Alloys with Excellent Biodegradation Performance

    Science.gov (United States)

    Hofstetter, J.; Becker, M.; Martinelli, E.; Weinberg, A. M.; Mingler, B.; Kilian, H.; Pogatscher, S.; Uggowitzer, P. J.; Löffler, J. F.

    2014-04-01

    This article deals with the development of fine-grained high-strength low-alloy (HSLA) magnesium alloys intended for use as biodegradable implant material. The alloys contain solely low amounts of Zn and Ca as alloying elements. We illustrate the development path starting from the high-Zn-containing ZX50 (MgZn5Ca0.25) alloy with conventional purity, to an ultrahigh-purity ZX50 modification, and further to the ultrahigh-purity Zn-lean alloy ZX10 (MgZn1Ca0.3). It is shown that alloys with high Zn-content are prone to biocorrosion in various environments, most probably because of the presence of the intermetallic phase Mg6Zn3Ca2. A reduction of the Zn content results in (Mg,Zn)2Ca phase formation. This phase is less noble than the Mg-matrix and therefore, in contrast to Mg6Zn3Ca2, does not act as cathodic site. A fine-grained microstructure is achieved by the controlled formation of fine and homogeneously distributed (Mg,Zn)2Ca precipitates, which influence dynamic recrystallization and grain growth during hot forming. Such design scheme is comparable to that of HSLA steels, where low amounts of alloying elements are intended to produce a very fine dispersion of particles to increase the material's strength by refining the grain size. Consequently our new, ultrapure ZX10 alloy exhibits high strength (yield strength R p = 240 MPa, ultimate tensile strength R m = 255 MPa) and simultaneously high ductility (elongation to fracture A = 27%), as well as low mechanical anisotropy. Because of the anodic nature of the (Mg,Zn)2Ca particles used in the HSLA concept, the in vivo degradation in a rat femur implantation study is very slow and homogeneous without clinically observable hydrogen evolution, making the ZX10 alloy a promising material for biodegradable implants.

  2. Study on hemocompatibility and corrosion behavior of ion implanted TiNi shape memory alloy and Co-based alloys.

    Science.gov (United States)

    Liang, Chenghao; Huang, Naibao

    2007-10-01

    Biomedical TiNi shape memory alloy and Co-based alloys were ion implanted, and corrosion resistance and hemocompatibility of these had been investigated with electrochemical method, dynamic clotting time, and hemolysis rate tests. The results indicated that the electrochemical stability and anodic polarization behavior of the materials were improved significantly after ion implantation. When TiNi, Co-based alloys were implanted Mo + C and Ti + C, respectively, the corrosion potentials were enhanced more than 200 mV, passive current densities decreased, and passive ranges were broadened. Dynamic clotting time of the ion implanted substances was prolonged and hemolysis rate decreased. All the results pointed out that corrosion resistance and hemocompatibility of the alloys were improved by ion implantation, and effects of dual implantation was better than that of C single implantation. X-ray diffraction analysis of the alloys after dual implantation revealed that TiC, Mo(2)C, Mo(9)Ti(4), and Mo appeared on the surface of TiNi alloy, and CoC(x), Co(3)Ti, TiC, and TiO on the surface of Co-based alloys. These phases dispersing on the alloy surface formed amorphous film, prevented dissolving of alloy elements and improved the corrosion resistance and hemocompatibility of the alloys.

  3. EFFECT OF PRE-ALLOYING CONDITION ON THE BULK AMORPHOUS ALLOY ND(60)FE(30)AL(10).

    Energy Technology Data Exchange (ETDEWEB)

    OCONNOR,A.S.; LEWIS,L.H.; MCCALLUM,R.W.; DENNIS,K.W.; KRAMER,M.J.; KIM ANH,D.T.; DAN,N.H.; PHUC,N.X.

    2000-09-10

    Bulk metallic glasses are materials that require only modest cooling rates to obtain amorphous solids directly from the melt. Nd{sub 60}Fe{sub 30}Al{sub 10} has been reported to be a ferromagnetic bulk metallic glass that exhibits high coercivity, a combination unlike conventional Nd-based amorphous magnetic alloys. To clarify the relationship between short-range order and high coercivity in glassy Nd{sub 60}Fe{sub 30}Al{sub 10}, experiments were performed to verify the existence of a homogeneous liquid state prior to rapid solidification. Alloys were prepared by various pre-alloying routes and then melt-spun. Arc-melted alloys were prepared for melt spinning using three different protocols involving: (1) alloying all three elements at once, (2) forming a Nd-Fe alloy which was subsequently alloyed with Al, and (3) forming a Fe-Al alloy for subsequent alloying with Nd. XRD, DTA, and magnetic measurement data from the resultant ribbons indicate significant differences in both the glassy fraction and the crystalline phase present in the as-spun material. These observed differences are attributed to the presence of highly stable nanoscopic aluminide-and/or silicide-phases, or motes, present in the melt prior to solidification. These motes would affect the short-range order and coercivity of the resultant glassy state and are anticipated to provide heterogeneous nucleation sites for crystallization.

  4. Thermodynamics and surface properties of liquid Al-Ga and Al-Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Anusionwu, B.C. [Abdus Salam Int. Centre for Theoretical Physics, Trieste (Italy); Federal University of Technology, Department of Physics, Owerri (Nigeria); Adebayo, G.A. [Abdus Salam Int. Centre for Theoretical Physics, Trieste (Italy); University of Agriculture, Department of Physics, Abeokuta (Nigeria); Madu, C.A. [Federal University of Technology, Department of Physics, Owerri (Nigeria)

    2009-11-15

    The surface properties of Al-Ga and Al-Ge liquid alloys have been theoretically investigated at a temperature of 1100 K and 1220 K respectively. For the Al-Ga system, the quasi chemical model for regular alloy and a model for phase segregating alloy systems were applied, while for the Al-Ge system the quasi chemical model for regular and compound forming binary alloys were applied. In the case of Al-Ga, the models for the regular alloys and that for the phase segregating alloys produced the same value of order energy and same values of thermodynamic and surface properties, while for the Al-Ge system, the model for the regular alloy reproduced better the thermodynamic properties of the alloy. The model for the compound forming systems showed a qualitative trend with the measured values of the thermodynamic properties of the Al-Ge alloy and suggests the presence of a weak complex of the form Al{sub 2}Ge{sub 3}. The surface concentrations for the alloys show that Ga manifests some level of surface segregation in Al-Ga liquid alloy while the surface concentration of Ge in Al-Ge liquid alloy showed a near Roultian behavior below 0.8 atomic fraction of Ge. (orig.)

  5. Thermodynamics and surface properties of liquid Al-Ga and Al-Ge alloys

    Science.gov (United States)

    Anusionwu, B. C.; Adebayo, G. A.; Madu, C. A.

    2009-11-01

    The surface properties of Al-Ga and Al-Ge liquid alloys have been theoretically investigated at a temperature of 1100 K and 1220 K respectively. For the Al-Ga system, the quasi chemical model for regular alloy and a model for phase segregating alloy systems were applied, while for the Al-Ge system the quasi chemical model for regular and compound forming binary alloys were applied. In the case of Al-Ga, the models for the regular alloys and that for the phase segregating alloys produced the same value of order energy and same values of thermodynamic and surface properties, while for the Al-Ge system, the model for the regular alloy reproduced better the thermodynamic properties of the alloy. The model for the compound forming systems showed a qualitative trend with the measured values of the thermodynamic properties of the Al-Ge alloy and suggests the presence of a weak complex of the form Al2Ge3. The surface concentrations for the alloys show that Ga manifests some level of surface segregation in Al-Ga liquid alloy while the surface concentration of Ge in Al-Ge liquid alloy showed a near Roultian behavior below 0.8 atomic fraction of Ge.

  6. 超声半固态流变挤压成形Al-20Si-2Cu-0.4Mg-1Ni合金的组织特征%Microstructural characteristics of Al-20Si-2Cu-0.4Mg-1Ni alloy formed by rheo-squeeze casting after ultrasonic vibration treatment

    Institute of Scientific and Technical Information of China (English)

    吴树森; 钟鼓; 安萍; 万里; 中江秀雄

    2012-01-01

    A swash plate for air conditioning compressor of cars was formed by rheo-squeeze casting with semi-solid Al-Si alloy slurry prepared by ultrasonic vibration process,and the microstructure of this alloy was investigated.Besides the microstructures of primary Si particles and α(Al)+β-Si eutectic phases,non-equilibrium α(Al)particles or dendrites are discovered in the microstructure of the Al-20Si-2Cu-0.4Mg-1Ni alloy.Rapid cooling generated by squeeze casting process rather than the pressure is considered as the main reason for the formation of non-equilibrium α(Al)phase.The sound pressurizing effect of ultrasonic vibration also enables the non-equilibrium α(Al)phases to form above eutectic temperature and grow into non-dendritic spheroids in the process of semi-solid slurry preparation.Non-equilibrium α(Al)phases formed in the hypereutectic Al-Si alloy with ultrasonic vibration treatment,consist of round α(Al)grains formed above the eutectic temperature and a small amount of fine α(Al)dendrites formed under the eutectic temperature.The volume fraction of primary Si particles is decreased significantly by the effect of ultrasonic vibration through increasing the solid solubility of Si atoms in α(Al)matrix and decreasing the forming temperature range of primary Si particles.The average particle diameter and the volume fraction of primary Si particles in microstructure of the swash-plate by rheo-squeeze casting are 24.3 μm and 11.1%,respectively.%通过超声振动半固态流变挤压铸造工艺制造汽车空调压缩机铝硅合金斜盘零件,研究合金的组织特征.发现在Al-20Si-2Cu-0.4Mg-1Ni合金的组织中,除了通常具有的初晶Si和α(Al)+β-Si共晶相之外,还有非平衡α(Al)颗粒或枝晶.挤压铸造过程中的较快的冷却速度而非压力是非平衡α(Al)相形成的主要原因.在半固态浆料的制备过程中,超声振动的声压作用能促进非平衡α(Al)相在共晶温度以上生成,并生长为非枝晶颗

  7. Formation and characterization of Al-Ti-Nb alloys by electron-beam surface alloying

    Science.gov (United States)

    Valkov, S.; Petrov, P.; Lazarova, R.; Bezdushnyi, R.; Dechev, D.

    2016-12-01

    The combination of attractive mechanical properties, light weight and resistance to corrosion makes Ti-Al based alloys applicable in many industrial branches, like aircraft and automotive industries etc. It is known that the incorporation of Nb improves the high temperature performance and mechanical properties. In the present study on Al substrate Ti and Nb layers were deposited by DC (Direct Current) magnetron sputtering, followed by electron-beam alloying with scanning electron beam. It was chosen two speeds of the specimen motion during the alloying process: V1 = 0.5 cm/s and V2 = 1 cm/s. The alloying process was realized in circular sweep mode in order to maintain the melt pool further. The obtained results demonstrate a formation of (Ti,Nb)Al3 fractions randomly distributed in biphasic structure of intermetallic (Ti,Nb)Al3 particles, dispersed in α-Al solid solution. The evaluated (Ti,Nb)Al3 lattice parameters are independent of the speed of the specimen motion and therefore the alloying speed does not affect the lattice parameters and thus, does not form additional residual stresses, strains etc. It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. The metallographic analyses demonstrate a formation of surface alloys with very high hardness. Our results demonstrate maximal values of 775 HV [kg/cm2] and average hardness of 673 HV [kg/cm2].

  8. PLUTONIUM-ZIRCONIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  9. Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy

    Science.gov (United States)

    Alhazaa, Abdulaziz Nasser

    The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength and light weight properties necessary for the transport industry. However, the large difference in the physical properties between these two alloys prevents the use of conventional joining techniques such as fusion welding to join these dissimilar alloys. Therefore, the diffusion bonding technique was used to join Al7075 alloy to Ti-6Al-4V alloy with the objective of minimizing microstructural changes of the two alloys during the bonding process. In this thesis, solid state and liquid phase bonding processes were undertaken. Solid state bonding was employed without interlayers and was successful at 510°C and 7 MPa. The bond interface showed an absence of the oxides due to the dissolution of oxygen into the titanium solution. Bonds made using copper interlayers at a temperature sufficient enough to form eutectic liquid formation between copper and aluminum were produced. The intermetallics theta(Al2Cu), S(Al2CuMg) and T(Al2Mg3Zn3) were identified at the aluminum interface while Cu3Ti2 intermetallic was identified at the titanium interface. Bonds made using tin based alloys interlayers and copper coatings were successful and gave the highest shear strength. The eutectic formation on the Al7075 alloy was responsible for joint formation at the aluminum interface while the formation of Sn3Ti5 intermetallic was responsible for the joint formation at titanium interface. The corrosion rate of the bonds decreased with increasing bonding time for joints made using the tin based interlayer in 3% NaCl solution. However, the presence of copper within the joint increased the corrosion rate of the bonds and this was attributed to

  10. NICKEL-BASE ALLOY

    Science.gov (United States)

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  11. Studies on Preparation and Corrosion Resistance of Molybdate Conversion Coating Formed on AZ91 Magnesium Alloy%AZ91镁合金钼酸盐转化膜的制备及耐蚀性研究

    Institute of Scientific and Technical Information of China (English)

    王明; 邵忠财; 姜海涛

    2012-01-01

    采用化学转化法在AZ91镁合金基体表面制备一种环境友好型的钼酸盐转化膜.通过对溶液pH、温度以及Na2MoO4质量浓度等因素的控制并进行单因素试验和正交试验,确定化学转化的最佳工艺条件:30~40 g/L Na2 MoO4,pH为3.5,θ为70℃,t为50 min.采用优化后的工艺能够在镁合金表面获得微黄致密,微细裂纹的膜层,X-射线衍射测试表明,钼酸盐转化膜的主要成分Mg2Mo3O8和MgMoO4.极化曲线测试表明钼酸盐转化膜能有效提高镁合金的耐蚀性能,自腐蚀电位提高,自腐蚀电流密度降低2个数量级.%An environmental friendly molybdate conversion coating was prepared on AZ91 magnesium alloy by chemical conversion method. The factors such as pH value, temperature and mass concentration of Na2MoO4 were investigated by single factor experiment and orthogonal experiments, and the optimum conditions of chemical conversion were determined as following:pH 3.5,temperature 70℃,30 ~40g/L Na2MoO4 and chemical conversion time 50min. The macro surface morphology of as-prepared coating on Mg-based substrate was compact and yellowish, while presenting microscopic small cracks. XRD showed that main component of the molybdate conversion coating were Mg2Mo3Og and MgMoO4. Electrochemical polarization test analysis showed that the molybdate conversion coating could effectively improving the corrosion resistance of magnesium alloy and increasing the self- corrosion potential, and the self- corrosion current density was decreased by two orders of magnitude.

  12. Oxidation mechanisms for alloys in single-oxidant gases

    Energy Technology Data Exchange (ETDEWEB)

    Whittle, D.P.

    1981-03-01

    Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.

  13. Order/disorder in electrodeposited aluminum-titanium alloys

    Directory of Open Access Journals (Sweden)

    Stafford G.R.

    2003-01-01

    Full Text Available The composition, morphology, and crystallographic microstructure of Al-Ti alloys electrodeposited from two different chloroaluminate molten salt electrolytes were examined. Alloys containing up to 28 % atomic fraction Ti were electrodeposited at 150 °C from 2:1 AlCl3-NaCl with controlled additions of Ti2+. The apparent limit on alloy composition is proposed to be due to a mechanism by which Al3Ti forms through the reductive decomposition of [Ti(AlCl43]-. The composition of Al-Ti alloys electrodeposited from the AlCl3-EtMeImCl melt at 80 °C is limited by the diffusion of Ti2+ to the electrode surface. Alloys containing up to 18.4 % atomic fraction Ti are only obtainable at high Ti2+ concentrations in the melt and low current densities. Alloys electrodeposited from the higher temperature melt have an ordered L12 crystal structure while alloys of similar composition but deposited at lower temperature are disordered fcc. The appearance of antiphase boundaries in the ordered alloys suggests that the deposit may be disordered initially and then orders in the solid state, subsequent to the charge transfer step and adatom incorporation into the lattice. This is very similar to the disorder-trapping observed in rapidly solidified alloys. The measured domain size is consistent with a mechanism of diffusion-controlled doman growth at the examined deposition temperatures and times.

  14. Synthesis of Al/Al sub 3 Ti two-phase alloys by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, S.; Chen, S.R.; Schwarz, R.B.

    1991-01-01

    We have mechanically alloyed mixtures of elemental powders to prepare fine-grain two-phase A1/A1{sub 3}Ti powders at the compositions A1-20at% Ti and Al-10at% Ti. Hexane was used to prevent agglomeration of the powder during MA. Carbon from the decomposition of the hexane was incorporated in the powder. It reacted with Ti to form a fine dispersion of carbides in the final hot-pressed compact. We consolidated the mechanically alloyed powders by hot-pressing. Yield strength and ductility were measured in compression. At 25{degree}C, the compressive yield strengths were 1.25 and 0.6 GPa for the A1-20at% Ti and Al-10at% Ti alloys, respectively. The ductility of the A1-10at% Ti alloy exceeded 20% for 25 < T < 500{degree}C. 25 refs., 6 figs.

  15. Structure of nanocomposites of Al–Fe alloys prepared by mechanical alloying and rapid solidification processing

    Indian Academy of Sciences (India)

    S S Nayak; B S Murty; S K Pabi

    2008-06-01

    Structures of Al-based nanocomposites of Al–Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe2 appeared. Subsequent annealing at 673 K resulted in more Al5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with -Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP.

  16. Interface properties and phase formation between surface coated SKD61 and aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Se-Weon CHOI; Young-Chan KIM; Se-Hun CHANG; Ik-Hyun OH; Joon-Sik PARK; Chang-Seog KANG

    2009-01-01

    The intermediate phase formation and surface protection effects between SKD61 die mold alloys and aluminum alloys were investigated during a simulated die-casting process. The surface coatings of SKD61 alloy were carried out via Si pack cementation coatings at 900 ℃ for 10 h and the e-FeSi phase formed. When the coated SKD61 alloy was dipped in the liquid aluminum alloy (ALDC12), the surface coated SKD61 alloys showed better surface properties compared with uncoated SKD61 alloys, i.e., the intermediate phases (FeSiAl compound) were not produced for the coated SKD61 alloy. The coating layer of e-FeSi served as a diffusion barrier for the formation of FeSiAl compounds.

  17. Nanodispersed boriding of titanium alloy

    Directory of Open Access Journals (Sweden)

    Kateryna O. Kostyk

    2015-12-01

    Full Text Available The problem of improving the operational reliability of machines is becoming increasingly important due to the increased mechanical, thermal and other loads on the details. There are many surface hardening methods for machines parts which breakdown begins with surface corruption. The most promising methods are chemo-thermal treatment. Aim: The aim of this work is to study the impact of boriding on the structure and properties of titanium alloy. Materials and Methods: The material of this study is VT3-1 titanium alloy. The boriding were conducted using nanodispersed powder blend based on boric substances. Results: It is established that boriding of paste compounds allows obtaining the surface hardness within 30...29 GPa and with declining to 27...26 GPa in layer to the transition zone (with total thickness up to 110 μm owing to changes of the layer phase composition where Ti2B, TiB, TiB2 titanium borides are formed. The increasing of chemical-thermal treatment time from 15 minutes to 2 hours leads to thickening of the borated layer (30...110 µm and transition zone (30...190 µm. Conclusions: Due to usage of nanodispersed boric powder, the boriding duration is decreasing in 2...3 times. This allows saving time and electric energy. The developed optimal mode of boriding the VT3-1 titanium alloy allows obtaining the required operational characteristics and to combine the saturation of the surface layer with atomic boron and hardening.

  18. Zirconium modified nickel-copper alloy

    Science.gov (United States)

    Whittenberger, J. D. (Inventor)

    1977-01-01

    An improved material for use in a catalytic reactor which reduces nitrogen oxide from internal combustion engines is in the form of a zirconium-modified, precipitation-strengthened nickel-copper alloy. This material has a nominal composition of Ni-30 Cu-0.2 Zr and is characterized by improved high temperature mechanical properties.

  19. Hydrogen Ingress in Steels During High-Temperature Oxidation in Water Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Michael P [ORNL; Fayek, Mostafa [ORNL; Keiser, James R [ORNL; Meyer III, Harry M [ORNL; More, Karren Leslie [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Wesolowski, David J [ORNL; Cole, David R [ORNL

    2011-01-01

    It is well established that hydrogen derived from water vapour can penetrate oxidizing alloys with detrimental effect. However, the complexities of tracking hydrogen in these materials have prevented the direct profiling of hydrogen ingress needed to understand these phenomena. Here we report hydrogen profiles in industrially-relevant alumina- and chromia- forming steels correlated with the local oxide-metal nano/microstructure by use of SIMS D2O tracer studies and experimental protocols to optimize D retention. The D profiles unexpectedly varied markedly among the alloys examined, which indicates mechanistic complexity but also the potential to mitigate detrimental water vapour effects by manipulation of alloy chemistry.

  20. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  1. New developments in rapidly solidified magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K. [Allied-Signal, Inc., Morristown, NJ (United States); Chang, C.F. [Allied-Signal, Inc., Morristown, NJ (United States); Raybould, D. [Allied-Signal, Inc., Morristown, NJ (United States); King, J.F. [Magnesium Elektron Ltd., Manchester (United Kingdom); Thistlethwaite, S. [Magnesium Elektron Ltd., Manchester (United Kingdom)

    1992-12-31

    In the present paper, we will examine the new developments in the rapidly solidified Mg-Al-Zn-Nd (EA55RS) alloy. We shall first briefly review the process scale-up currently employed for producing rapidly solidified magnesium alloys in large quantities, and then discuss the effect of billet size and processing parameters on the mechanical properties of various mill product forms such as extrusions and sheets. The superplastic behavior of EA55RS extrusions and rolled sheets are also discussed. Finally, some results on magnesium metal-matrix composites using rapidly solidified EA55RS matrix powders and SiC particulates are presented. (orig.)

  2. Overlay metallic-cermet alloy coating systems

    Science.gov (United States)

    Gedwill, M. A.; Levine, S. R.; Glasgow, T. K. (Inventor)

    1984-01-01

    A substrate, such as a turbine blade, vane, or the like, which is subjected to high temperature use is coated with a base coating of an oxide dispersed, metallic alloy (cermet). A top coating of an oxidation, hot corrosion, erosion resistant alloy of nickel, cobalt, or iron is then deposited on the base coating. A heat treatment is used to improve the bonding. The base coating serves as an inhibitor to interdiffusion between the protective top coating and the substrate. Otherwise, the protective top coating would rapidly interact detrimentally with the substrate and degrade by spalling of the protective oxides formed on the outer surface at elevated temperatures.

  3. Methods for Electrodepositing Composition-Modulated Alloys

    DEFF Research Database (Denmark)

    Leisner, Peter; Nielsen, Christian Bergenstof; Tang, Peter Torben;

    1996-01-01

    Materials exhibiting unique mechanical, physical and chemical properties can be obtained by combining thin layers of different metals or alloys forming a multilayered structure. Two general techniques exist for electrodepositing composition-modulated alloy (CMA) materials; dual-bath and single......-bath plating. For both techniques a number of variations exist. The most suitable technique and variation for the manufacture of a certain CMA material is highly dependent on the metals included in the given CMA system and on the dimensions of the multilayered structure. In this paper, the main principles...

  4. Mg based alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, S. [Univ. de Santiago de Chile (Chile). Fac. de Ingenieria; Garcia, G.; Serafini, D.; San Martin, A.

    1999-07-01

    In the present work, we studied the production of magnesium alloys, of stoichiometry 2Mg + Ni, by mechanical alloying (MA) and the behavior of the alloys under hydrogen in a Sievert`s type apparatus. The elemental powders were milled under argon atmosphere in a Spex 8000 high energy ball mill. The milled materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Only minimum amounts of the Mg{sub 2}Ni intermetallic compound was obtained after 22 h of milling time. Most of the material was sticked to the inner surface of the container as well as to the milling balls. Powders milled only for 12 hours transforms to the intermetallic at around 433 K. Effects of the MA on the hydrogen absorption kinetics were also studied. (orig.) 10 refs.

  5. Comparison of corrosion behaviors of AZ31, AZ91,AM60 and ZK60 magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    CHENG Ying-liang; QIN Ting-wei; WANG Hui-min; ZHANG Zhao

    2009-01-01

    The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60>AM60>AZ31>AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.

  6. Recent Advances in the Hot Working of Titanium Alloys

    Institute of Scientific and Technical Information of China (English)

    DANG Xiao-ling

    2012-01-01

    In this paper, recent advances in titanium alloy processing are reviewed. The casting, superplastic forming, friction stir welding and thermohydrogen processing of titanium alloys are developed. The great cost saving results from using casting comparing with the conventional machining for rings. The superplastic forming of titanium alloys is a feasible manufacturing technology for civil and military aircraft. The friction stir welding leds to the production of fully-formed, high quality friction stirwelds. In thermohydrogen processing, the high diffusivity of hydrogen in titanium is firstly used to add hydrogen to titanium alloys by controlled diffusion from a hydrogen environment , after thermohydrogen processing, to remove it by a controlled vacuum anneal so as to improve processing and mechanical properties.

  7. Study on Degradation and Recovery of AB5-Type Hydrogen Storage Alloy Used in Ni-MH Batteries

    Institute of Scientific and Technical Information of China (English)

    王荣; 阎杰; 周震; 周作祥; 邓斌; 高学平

    2002-01-01

    The influences of deeply overdischarge on the negative electrode alloy of Ni/MH battery were studied. After overdischarge, La(OH)3 and Al(OH)3 are found to form in the negative electrode through XRD analysis. The hydrogen storage alloy powder from spent Ni/MH batteries was recovered by chemical and melting method according to degradation mechanism. The structure of recovered alloy was measured by XRD. The experimental results demonstrate that the alloy structure is CaCu5 type. The constant-current charge/discharge test was carried out to the original alloy and the recovered alloy. It is found that their discharge capacities are almost the same, but the discharge potential of the recovered alloy is higher than that of the original alloy. The results of cyclic lifetime test demonstrate that the capacity degradation of the recovered alloy is slower than that of the original one.

  8. Preliminary study of biodegradation of AZ31B magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    REN Yibin; HUANG Jingjing; ZHANG Bingchun; YANG Ke

    2007-01-01

    Magnesium alloys are potential to be developed as a new type of biodegradable implant material by use of their active corrosion behavior.Both in vitro and in vivo biodegradation properties of an AZ31B magnesium alloy were investigated in this work.The results showed that AZ31B alloy has a proper degradation rate and much lower hydrogen release in Hank's solution,with a degradation rate of about 0.3 mm/year and hydrogen release below 0.15mL/cm2.The animal implantation test showed that the AZ31B alloy could slowly biodegrade in femur of the rabbit and form calcium phosphate around the alloy sample,with the Ca/P ratio close to the natural bone.

  9. Alloying of metal nanoparticles by ion-beam induced sputtering

    Science.gov (United States)

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.

    2017-01-01

    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  10. Synthesis of aluminum-based scandium-yttrium master alloys

    Science.gov (United States)

    Bazhin, V. Yu.; Kosov, Ya. I.; Lobacheva, O. L.; Dzhevaga, N. V.

    2015-07-01

    The preparation technology for an Al-2% Sc-0.5% Y master alloy using aluminum-manganese alloys has been developed and tested. The microstructure of the prepared master alloy is studied and the compositions of intermetallics is determined. The efficient technological parameters of the synthesis are determined. It is shown that varying the compositions of starting reagents and alloying additions and optimizing the process conditions (temperature, mixing, etc.) allow us to forecast the manufacturing and operating characteristics of aluminum-based master alloys. Joint additions of scandium and yttrium oxides to a charge favor a substantial decrease in the grain size of the formed intermetallics; this effect appears to the utmost in the case of microallying with yttrium up to 0.5 wt %.

  11. Parametrized dielectric functions of amorphous GeSn alloys

    Science.gov (United States)

    D'Costa, Vijay Richard; Wang, Wei; Schmidt, Daniel; Yeo, Yee-Chia

    2015-09-01

    We obtained the complex dielectric function of amorphous Ge1-xSnx (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge0.75Sn0.25 and Ge0.50Sn0.50 alloys from literature. The compositional dependence of band gap energy Eg and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  12. Structure and properties of stir-cast zinc alloys

    Energy Technology Data Exchange (ETDEWEB)

    LeHuy, H.; Blain J.; Masounave, J.; Bata, G.L. (Industrial Materials Research Institute, Boucherville, P.Q. (Canada))

    Stir casting (or rheocasting) of ZA-27 zinc alloys was investigated experimentally. By vigorously agitating the alloys during cooling, the dendrites that were forming were fragmented giving a unique structure composed of spherical and rosette shaped particles suspended in the remaining liquid. Under high shear rates ({center dot}{gamma} = 300s{sup {minus}1} or more) the slurries with primary particle concentrations as high as 60% displayed viscosities as low as 20 poises and could easily be casted. The effects of processing variables such as shearing and cooling rates and casting temperatures were studied. Their relative importance on the rheological and microstructural behavior of the stir cast alloys are discussed. Results from viscosity measurements on slurries show that non-dendritical ZA-27 alloys obey a power law fluid model. Finally, results from mechanical and compressive studies carried out on solidified slurries are discussed and compared to conventional casted and wrought alloy properties.

  13. General aspects of surface alloy formation

    Energy Technology Data Exchange (ETDEWEB)

    Bergbreiter, Andreas; Engstfeld, Albert K.; Roetter, Ralf T.; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany); Berko, Andras

    2010-07-01

    Surface confined alloys are excellent model systems for studies of structure-property relationships of bimetallic surfaces. They are formed by deposition of a guest metal B onto a substrate A, followed by annealing to a temperature, where place exchange between adatoms and atoms from the underlying surface layer becomes possible and diffusion into the bulk is sufficiently slow. We exemplarily confirmed by scanning tunneling microscopy and Auger electron spectroscopy for PtRu/Ru(0001), PdRu/Ru(0001), AuPt/Pt(111), AgPt/Pt(111), and AgPd/Pd(111), surface alloys are obtained for systems where metal B has a negative surface segregation energy within metal A. By exchanging A and B, however, AB surface alloys are most likely overgrown by metal B, which we demonstrate for RuPt/Pt(111) in comparison to PtRu/Ru(0001).

  14. The open-circuit ennoblement of alloy C-22 and other Ni-Cr-Mo alloys

    Science.gov (United States)

    Lloydis, A. C.; Noël, J. J.; Shoesmith, D. W.; McIntyre, N. S.

    2005-01-01

    The open-circuit corrosion and anodic oxidation behavior of the C-series of Ni-Cr-Mo alloys (C-4, C-276, C-2000, and C-22) and alloy 625 have been studied at 25°C and 75°C in 1.0 mol·L-1 NaCl+1.0 mol·L-1 H2SO4. A combination of open-circuit potential, potentiostatic polarization, and electrochemical impedance spectroscopy were employed in the study. The composition of the films formed was determined by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Passive oxide film resistances increase and defect oxide film concentrations decrease as films thicken and chromium and molybdenum segregate to the alloy/oxide and oxide/solution interfaces, respectively. The high-chromium alloys exhibit higher film resistances and lower film defect concentrations consistent with the more positive potentials observed on these alloys. The results show that the observed ennoblement in corrosion potentials with time is coupled to the Cr/Mo segregation process and the suppression of defect injection at the alloy/oxide interface. By all measures, C-22 exhibited the best passive properties.

  15. Probing the nanoscale structure of the catalytically active overlayer on Pt alloys with rare earths

    DEFF Research Database (Denmark)

    Pedersen, Anders Filsøe; Ulrikkeholm, Elisabeth Therese; Escribano, Maria Escudero

    2016-01-01

    PtxY and PtxGd exhibit exceptionally high activity for oxygen reduction, both in the polycrystalline form and the nanoparticulate form. In order to understand the origin of the enhanced activity of these alloys, we have investigated thin films of these alloys on bulk Pt(111) crystals, i.e. Y/Pt(1...

  16. AZ91 D镁合金Mo-Mn无铬转化膜的制备与耐蚀性%Preparation and Corrosion Resistance of Mo-Mn Chromium-free Conversion Coating Formed on AZ91 D Magnesium Alloys

    Institute of Scientific and Technical Information of China (English)

    朱青; 朱明; 余勇; 张路路

    2015-01-01

    ABSTRACT:Objective To improve the surface corrosion resistance of AZ91D magnesium alloy by Mo-Mn chromium-free conver-sion coating. Methods Effects of different concentrations of NaMoO4 and KMnO4 and temperature on the transformed sample film were studied by orthogonal experimental method. After optimizing experiment parameters, the effects of the time on the conversion film was also studied. The morphology and component of conversion coatings were researched by SEM and EDS. Moreover, the po-larization curves and electrochemical impedance spectroscopy of conversion coating were tested in 3. 5%NaCl aqueous solution. Results The results showed that when the condition was 10 g/L NaMoO4 , 6 g/L KMnO4 at 50 ℃ and pH 5 for 40 min, where the morphology of the sample was relatively even and the amount of cracks was relatively low. Compared to the corrosion resistance of magnesium substrate, the corrosion potential of conversion film was increased by about 0. 075 V ,and the corrosion current density decreased by nearly 1 order of magnitude. When the condition was 20 g/L NaMoO4 , 8 g/L KMnO4 at 50 ℃ and pH 5 for 40 min, the morphology of the sample was the most even and the amount of cracks was the least. Compared to the corrosion resistance of magnesium substrate, the corrosion potential of conversion film was increased by about 0. 047 V ,and the corrosion current density decreased by nearly 2 orders of magnitude. EIS showed that the polarization resistance of the latter conversion film sample was 1450. 2 Ω, while the polarization resistance of magnesium matrix was 806. 4 Ω. Conclusion Mo-Mn chromium-free conversion coating could obviously improve the surface corrosion resistance of AZ91D magnesium alloy.%目的:通过Mo-Mn无铬转化膜提高AZ91 D镁合金的表面耐蚀性。方法采用正交实验法,研究不同浓度的NaMoO4和KMnO4以及温度对转化膜的影响。优选实验参数后,考察时间对转化膜的影响。利用SEM及EDS研究转化膜

  17. 40 CFR 468.10 - Applicability; description of the copper forming subcategory.

    Science.gov (United States)

    2010-07-01

    ... treatment works from the forming of copper and copper alloys except beryllium copper alloys. ... copper forming subcategory. 468.10 Section 468.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS COPPER FORMING POINT SOURCE CATEGORY Copper...

  18. 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

  19. Rheocasting techniques applied to intermetallic TiAl alloys and composites

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, K.; Kinoshita, Y. [Ministry of Int. Trade and Ind., Tsukuba, Ibaraki (Japan). Mech. Eng. Lab.

    1997-12-01

    An investigation was made on the homogenization of microstructures and improvement of mechanical properties in intermetallic TiAl binary, ternary and quaternary alloys and their composites produced by the rheocasting in which the solidifying alloy was vigorously agitated at rotation speeds of 15-70 s{sup -1} (900-4200 rpm) by a stirring rod immersed in the alloy in an argon gas atmosphere. In the microstructures of rheocast Ti-44 at.%Al alloy, such a lamellar structure in the alloy cast without stirring was disappeared completely and an extremely refined microstructure was formed. The crystal grain size of the rheocast Ti-44 at.%Al alloy was 2 {mu}m. The room temperature elongation of rheocast Ti-44%Al alloy exceeded 3%. The tensile strength of the alloy rheocast at 70 s{sup -1} and was 538 MPa at 1173 K and 439 MPa at 1273 K, respectively. Zirconium-rich lamellar grains and titanium-rich and carbon-rich precipitates, which were formed in the lamellar grains in a rheocast Ti-44 at%Al-5 vol.%ZrC alloy composite, were increased in a rheocast Ti-44%Al-10%ZrC alloy composite. Titanium-rich and carbon-rich precipitates, which were formed in the lamellar grains in a rheocast Ti-44%Al-10%TiC alloy composite, were increased in a rheocast Ti-46%Al-10%TiC alloy composite, and were decreased in a rheocast Ti-49%Al-10%TiC alloy composite. The elongation at room temperature and the tensile strength at 1373 K were 4% and 280 MPa, respectively, in a Ti-44 at.%Al-10 vol.%ZrC alloy composite. (orig.) 16 refs.

  20. PERSPECTIVES OF NANOPOWDERS APPLICATION FOR MANUFACTURING OF MODIFYING ALLOYING COMPOSITIONS

    Directory of Open Access Journals (Sweden)

    A. Kalinichenko

    2015-01-01

    Full Text Available Application of nanomaterials for grain refining of metals and its allac is of great interest as it aimis achieveto higher physicalmechanical properties in finished parts. Analysis shows that to gain high effectiveness of nanoparticles it is important to provide proper input of these particles into alloying alloy. The aim of present research is study of initial nanoparticles structure on the base of titanium, boron, yttrium and carbon nanotubes as well as development of method to manufacture alloying alloys containing nanoparticles.Investigations of nanopowders phase compositions on the base of titanium, boron and yttrium have shown that active elements such as boron carbide, titanium carbide and nitride, yttrium oxide are base compounds of these nanopowders. Powder particles are formed by primary structural elements having mainly plate state (titanium and boron carbides and containing equiaxial inclusions with sizes of 5–200 nm. Chemical composition of specimens synthesized is uniform and contains 98.0 – 99.5% of main compound.Results of metal-protector and nanoparticles mixing have revealed that the increase of mixing duration from 2 to 6 hours assist to more uniform elements distribution through the pellet volume. Applying extrusion method specimens of alloying alloys have been produced and elements distribution in cross-section and longitudinal directions were determined.Analysis of research implemented has shown that distribution of active nanopowders in matrix is more uniform in extruded alloying alloys specimens compared to ones produced by methods of sintering or pressing of powder mixtures.

  1. La doping effect on TZM alloy oxidation behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Wang, Kuai-She, E-mail: wangkuaishe888@126.com [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Hu, Ping; He, Huan-Cheng; Kang, Xuan-Qi [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Wang, Hua [Xi’an Electric Furnace Institute Co., Ltd., Xi’an 710061 (China); Liu, Ren-Zhi [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jinduicheng Molybdenum Co., Ltd., Xi’an 710068 (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa FL 33620 (United States)

    2014-04-01

    Highlights: • The oxidation can be resisted by doping La into TZM alloy. • La doped TZM alloy has more compact organization. • It can rise the starting temperature of severe oxidation reaction by more than 50 °C. • Effectively slow down the oxidation rate. • Provide guidance for experiments of improving high-temperature oxidation resistance. - Abstract: Powder metallurgy methods were utilized to prepare lanthanum-doped (La-TZM) and traditional TZM alloy plates. High temperature oxidation experiments along with the differential thermal analysis were employed to study the oxidation behavior of the two kinds of TZM alloys. An extremely volatile oxide layer was generated on the surface of traditional TZM alloy plates when the oxidation started. Molybdenum oxide volatilization exposed the alloy matrix, which was gradually corroded by oxygen, losing its quality with serious surface degradation. The La-TZM alloy has a more compact structure due to the lanthanum doping. The minute lanthanum oxide particles are pinned at the grain boundaries and refine the grains. Oxide layer generated on the matrix surface can form a compact coating, which effectively blocks the surface from being corroded by oxidation. The oxidation resistance of La-TZM alloys has been enhanced, expanding its application range.

  2. Synthesis, characterization, and microwave absorption properties of Fe-40 wt%Ni alloy prepared by mechanical alloying and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jun [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Feng Yongbao, E-mail: fengyongbao@163.com [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China); Qiu Tai [College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009 (China)

    2011-12-15

    Fe-40 wt%Ni alloys with granular shape and flake shape were prepared by a mechanical alloying (MA) and annealing method. The phase composition and morphology of the FeNi alloys, electromagnetic parameters, and microwave absorbing properties of the silicone rubber composite absorbers filled with the as-prepared FeNi alloy particles were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and vector network analyzer. The XRD results indicate that the crystalline structures of the Fe-40 wt%Ni alloys prepared by both one-step and two-step MA processes are face-centered cubic (fcc) Ni (Fe) solid solutions, and the structures can be retained after annealing at 600 deg. C for 2 h. SEM images show that the FeNi alloy powders for one-step process have a granular shape; however the particles turned into flake form when they were sequentially milled with absolute ethyl alcohol. With the increase in thickness of composite absorber, the reflection loss (RL) decreases, and the peak for minimum reflection loss shifts towards the lower frequency range. Compared to the absorbers filled with the granular FeNi alloy, the absorbers filled with flaky FeNi alloys possess higher complex permittivities and permeabilities and have a lower RL and peak frequency under the same thickness. Microwave absorbing materials with a low reflection loss peak in the range of 1-4 GHz are obtained, and their microwave absorbing properties can be adjustable by changing their thicknesses. - Highlights: > We prepare face-centered cubic (FCC) Ni (Fe) solid solutions by mechanical alloying and annealing. > Shape of FeNi alloy powder changes from granular to flaky after wet-milling. > Absorbers containing flaky FeNi alloys possess higher electromagnetic parameters. > MAMs with low reflection loss peak in the range of 1-4 GHz are obtained. > Microwave absorbing properties can be adjustable by modifying the thickness of the absorbers.

  3. Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

  4. 40 CFR 468.20 - Applicability; description of the beryllium copper forming subcategory.

    Science.gov (United States)

    2010-07-01

    ... of pollutants into publicly owned treatment works from the forming of beryllium copper alloys. ... beryllium copper forming subcategory. 468.20 Section 468.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS COPPER FORMING POINT SOURCE...

  5. Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates

    Energy Technology Data Exchange (ETDEWEB)

    Poineau, Frederic [Univ. of Nevada, Las Vegas, NV (United States); Tamalis, Dimitri [Florida Memorial Univ., Miami Gardens, FL (United States)

    2016-08-01

    The isotope 99Tc is an important fission product generated from nuclear power production. Because of its long half-life (t1/2 = 2.13 ∙ 105 years) and beta-radiotoxicity (β⁻ = 292 keV), it is a major concern in the long-term management of spent nuclear fuel. In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up. In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form. Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass. In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository. Metallic alloys under consideration include Tc–Zr alloys, Tc–stainless steel alloys and Tc–Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long-term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed, but efforts to model the behavior of Tc metallic alloys are limited. One parameter that should also be considered in predicting the long-term behavior of the Tc waste form is the ingrowth of stable Ru that occurs from the radioactive decay of 99Tc (99Tc → 99Ru + β⁻). After a geological period of time, significant amounts of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance. In this context, we studied the electrochemical behavior of Tc metal, Tc-Ni alloys (to model Tc-Inconel alloy) and Tc-Ru alloys in acidic media. The study of Tc-U alloys has also been performed in order to better understand the

  6. Segregation phenomena at growing alumina/alloy interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Peggy Y.

    2005-03-30

    The chemistry and structure at the scale/alloy interface are important factors governing scale adhesion. The chemical changes can occur from segregation of impurities in the alloy, such as sulphur and carbon, or alloying elements such as chromium, aluminium and reactive elements. This paper reviews studies of the changes of interfacial composition with oxidation time for Al{sub 2}O{sub 3} formed on several model alumina-forming alloys, and tries to relate that to the interfacial strength. Results show that sulphur segregation to oxide/metal interfaces can indeed occur, but the type and amount of segregants at the interface depend on the alloy composition and the interface structure. Co-segregation of impurities with alloying elements can also occur, resulting in multi-layer segregants at the interface. Sulphur-containing interfaces are indeed weaker, but the major role of sulphur is to enhance interfacial void formation. Reactive elements in the alloy not only gather sulfur but also exert an additional positive effect on scale adhesion.

  7. Performance evaluation of several commercial alloys in a reducing environment

    Science.gov (United States)

    Liu, Y.

    Several commercial alloys including Ebrite, Crofer 22 APU, Haynes 230 and Haynes 242, which are candidates for intermediate-temperature solid oxide fuel cell (SOFC) interconnect materials, were isothermally and cyclically oxidized at 900 °C in the reducing atmosphere of Ar + 5 vol.% H 2 + 3 vol.% H 2O corresponding to the SOFC anode environment. Results indicate that these alloys exhibited good scale spallation resistance with the Ni-base alloys possessing better oxidation resistance over the Fe-base alloys. Both Mn-Cr spinel and Cr 2O 3 were formed in the oxide scales of these alloys. For Crofer 22 APU and Haynes 242, a continuous protective MnO and Mn-Cr spinel layer formed outside on the inner layer of Cr 2O 3. The increase in scale ASR after longer-term thermal exposure in the reducing environment was relatively slower for the Ni-base alloys than for the Fe-base alloys.

  8. Innovative forming and fabrication technologies : new opportunities.

    Energy Technology Data Exchange (ETDEWEB)

    Davis, B.; Hryn, J.; Energy Systems; Kingston Process Metallurgy, Inc.

    2008-01-31

    The advent of light metal alloys and advanced materials (polymer, composites, etc.) have brought the possibility of achieving important energy reductions into the full life cycle of these materials, especially in transportation applications. 1 These materials have gained acceptance in the aerospace industry but use of light metal alloys needs to gain wider acceptance in other commercial transportation areas. Among the main reasons for the relatively low use of these materials are the lack of manufacturability, insufficient mechanical properties, and increased material costs due to processing inefficiencies. Considering the enormous potential energy savings associated with the use of light metal alloys and advanced materials in transportation, there is a need to identify R&D opportunities in the fields of materials fabrication and forming aimed at developing materials with high specific mechanical properties combined with energy efficient processes and good manufacturability. This report presents a literature review of the most recent developments in the areas of fabrication and metal forming focusing principally on aluminum alloys. In the first section of the document, the different sheet manufacturing technologies including direct chill (DC) casting and rolling, spray forming, spray rolling, thin slab, and strip casting are reviewed. The second section of the document presents recent research on advanced forming processes. The various forming processes reviewed are: superplastic forming, electromagnetic forming, age forming, warm forming, hydroforming, and incremental forming. Optimization of conventional forming processes is also discussed. Potentially interesting light metal alloys for high structural efficiency including aluminum-scandium, aluminum-lithium, magnesium, titanium, and amorphous metal alloys are also reviewed. This section concludes with a discussion on alloy development for manufacturability. The third section of the document reviews the latest

  9. Strength of Hard Alloys,

    Science.gov (United States)

    Partial replacement of titanium carbide by tantalum carbide in three-phase WC-TiC-Co alloys tends to have a favorable effect on mechanical properties such as fatigue strength under bending and impact durability.

  10. Alloy Selection System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  11. Electrolyte Optimization of Microarc Oxidation of Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    FANGDa-ran; WANGJi-hui; YANGJing

    2004-01-01

    Magnesium alloy AZ91D was processed respectively in one, two, three and four-component electrolytes by using AC microarc oxidation technique. The corrosion resistance of AZ91D alloy was measured by electrochemical methods. The optimum electrolytes in two, three and four components were found. In four-component electrolyte composed by NaOH, NaAlO2, H2O2 and C4H4O6Na2, the film formed on AZ91D alloy is smooth and compact, and has a higher corrosion resistance. The effect of the ingredients in electrolytes was discussed based on their roles in the formation of corrosion resistant film.

  12. Electrolyte Optimization of Microarc Oxidation of Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    FANG Da-ran; WANG Ji-hui; YANG Jing

    2004-01-01

    Magnesium alloy AZ91D was processed respectively in one, two, three and four-component electrolytes by using AC microarc oxidation technique. The corrosion resistance of AZ9 1D alloy was measured by electrochemical methods. The optimum electrolytes in two, three and four components were found. In four-component electrolyte composed by NaOH,NaAlO2, H2O2 and C4H4O6Na2, the film formed on AZ91D alloy is smooth and compact, and has a higher corrosion resistance. The effect of the ingredients in electrolytes was discussed based on their roles in the formation of corrosion resistant film.

  13. Structure evolution of AZ61 magnesium alloy in SIMA process

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; ZHANG Fa-yun; JIE Xiao-ping

    2005-01-01

    The effect of prior compressive deformation, isothermal temperature and holding time on the structure of AZ61 magnesium alloy fabricated by strain-induced melt activation(SIMA) processing was investigated. The specimens were subjected under deformation ratios of 0%, 22% and 40% and various heat treatment time and temperature regions. The results indicate that the ideal technological parameters of semi-solid AZ61 alloy produced with non-dendrites are recommended as 22% (prior compressive deformation), 595 ℃ (heat treatment temperature) and 40 min(time). The as-cast AZ61 magnesium alloy isn't fit for semi-solid forming.

  14. Approaches to oxidation-resistant refractory metal alloys

    OpenAIRE

    Wright, I; Nagarajan, V.

    1993-01-01

    The focus of the research reported here was on the design of high-temperature alloys which would form protective SiO2 and Al2O3 scales on exposure to high-temperature, oxidizing environments. One way to promote the growth of such scales is to incorporate sufficient amounts of Si or Al in the alloy substrate ; typically, additions of approximately 35 to 45 weight percent (all alloy compositions are given in weight percent unless explicitly stated otherwise) of Si or Al would be required to for...

  15. Titanium-zirconium-phosphonate hybrid film on 6061 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Shuanghong WANG; Lei WANG; Changsheng LIU

    2011-01-01

    Three titanium-zirconium-phosphonate hybrid films were formed on AA6061 aluminum alloy by immersing in fluorotitanic acid and fluorozirconic acid based solution containing different phosphonic acids for protective coatings of aluminium alloy. The corrosion resistance of three hybrid films as the substitute for chromate film were evaluated and compared. The neutral salt spray test was explored,the immersion test was conducted and electrochemical test was also executed. The hybrid films exhibited well-pleasing corrosion resistance and adhesion to epoxy resin paints. It was found out that the hybrid films could efficiently be a substitute for chromate based primer over aluminium alloy.

  16. Composition Control of Alloy Coatings and Composition Designof Cathode Targets in Multi-Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The composition from alloy cathode target to alloy coating generally changes to some extentin multi-arc ion plating. This demixing effect leads to the difficulties in the control of alloycomposition of coating and in the design of composition of alloy cathode target. A new simple formula,is proposed in present work to deal with the problem. According to this formula, the composition of alloy coating can be calculated bymeans of the degrees of ionization of alloy elements. The results of calculation agree with theexperimental ones within very limited error range. Modifying the formula into another form,the design for alloy composition of cathode target can be conveniently carried out, and the ideal composition of alloy coating can be obtained.

  17. Effects of Ce on damping capacity of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    黄正华; 郭学锋; 张忠明

    2004-01-01

    The microstructures and damping capacity of AZ91D cast alloys containing various Ce contents were investigated. Damping capacity (Q-1) of the alloys was measured by cantilever beam technique, and the relationship between damping capacity and strain amplitude was investigated. The results show that Al4 Ce phase is formed in AZ91D alloy after adding a certain quantity of Ce contents, then as-cast microstructures of the alloys are refined.Meanwhile the damping capacity of the alloys is also improved. When the mass fraction of Ce is 0.7 %, the most obvious refinement effect and the maximum damping capacity can be obtained. When the damping capacity (Q-1) is 2. 728 × 10-3 , 61% increment can be obtained compared with unmodified AZ91D alloy. The damping capacity of the alloys is relative to strain amplitude, and the damping behavior can be explained by the theory of Granato and Lucke.

  18. Study on comprehensive properties of duplex austenitic surfacing alloys for impacting abrasion

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, comprehensive property crack resistance, work hardening and abrasion resistance of a series of double-phases austenitic alloys(FAW) has been studied by means of SEM, TEM and type MD-10 impacting wear test machine. FAW alloys are of middle chromium and low manganese, including Fe-Cr-Mo-C alloy,Fe-Cr-Mn-C alloy and Fe-Cr-Mn-Ni-C alloy, that are designed for working in condition of impacting abrasion resistance hardfacing.Study results show that the work hardening mechanism of FAW alloys are mainly deformation high dislocation density and dynamic carbide aging, the form of wearing is plastic chisel cutting. Adjusting the amount of carbon, nickel, manganese and other elements in austenitic phase area, the FAW alloy could fit different engineering conditions of high impacting, high temperature and so on.

  19. Calculating formation range of binary amorphous alloys fabricated by electroless plating

    Science.gov (United States)

    Zhang, Bangwei; Liao, Shuzhi; Shu, Xiaolin; Xie, Haowen

    2016-06-01

    A lot of amorphous alloy deposits in the binary (Ni, Co, Cu)-(P, B) alloy systems fabricated by electroless plating (EP) have been reported up to date. But no one reported their theoretical modeling of the amorphous formation and calculated their concentration range of amorphous formation (RAF). Using Miedema model and subregular model scheme, the RAFs for the six EP (Ni, Co, Cu)-(P, B) alloys and three Ni-Cu, Ni-Co and Co-Cu alloys have been calculated systematically for the first time. The calculated results are in agreement with experimental observations. Experiments and calculations for the RAFs in the latter three alloy systems reveal that not any RAF formed except crystalline states. The huge difference between the six metal-metalloid alloys and three metal-metal alloys in RAF has been discussed in detail in the paper.

  20. Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Rebak, R B

    2005-11-04

    Alloy 22 (N06022) is a nickel based alloy containing alloying elements such as chromium, molybdenum and tungsten. It is highly corrosion resistant both under reducing and under oxidizing conditions. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. Tests were also carried out in NaCl solutions containing oxalic acid or acetic acid. It is shown that the corrosion rate of Alloy 22 was higher in a solution containing oxalic acid than in a solution of the same pH acidified with HCl. Acetic acid was not corrosive to Alloy 22. The corrosivity of oxalic acid was attributed to its capacity to form stable complex species with metallic cations from Alloy 22.

  1. Improving Corrosion Resistance of Q235 Steel by Ni-Cr Alloyed Layer

    Institute of Scientific and Technical Information of China (English)

    HUANG Jun; ZHANG Pingze; WU Hongyan; BI Qiang

    2012-01-01

    Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate.The composition and microstructure of alloyed layer was analyzed by SEM and XRD.Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer.The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer,and the dense and smooth alloyed layer was prepared at 50 Pa working pressure.Compared with substrate,Ni-Cr alloyed layer exhibited higher corrosion potential,lower corrosion current density and larger charge transfer resistance,which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.

  2. Effect of Zn addition on microstructure and mechanical properties of an Al–Mg–Si alloy

    Directory of Open Access Journals (Sweden)

    Lizhen Yan

    2014-04-01

    Full Text Available In the present work, an Al–0.66Mg–0.85Si–0.2Cu alloy with Zn addition was investigated by electron back scattering diffraction (EBSD, high resolution electron microscopy (HREM, tensile and Erichsen tests. The mechanical properties of the alloy after pre-aging met the standards of sheet forming. After paint baking, the yield strength of the alloy was improved apparently. GP(II zones and ηʹ phases were formed during aging process due to Zn addition. With the precipitation of GP zones, β″ phases, GP(II zones and ηʹ phases, the alloys displayed excellent mechanical properties.

  3. Effect of Zn addition on microstructure and mechanical properties of an Al-Mg-Si alloy

    Institute of Scientific and Technical Information of China (English)

    Lizhen Yan; Yongan Zhang; Xiwu Li; Zhihui Li; Feng Wang; Hongwei Liu; Baiqing Xiong

    2014-01-01

    In the present work, an Al-0.66Mg-0.85Si-0.2Cu alloy with Zn addition was investigated by electron back scattering diffraction (EBSD), high resolution electron microscopy (HREM), tensile and Erichsen tests. The mechanical properties of the alloy after pre-aging met the standards of sheet forming. After paint baking, the yield strength of the alloy was improved apparently. GP(II) zones andηʹphases were formed during aging process due to Zn addition. With the precipitation of GP zones,β″phases, GP(II) zones andηʹphases, the alloys displayed excellent mechanical properties.

  4. First Everlasting Alloy

    Institute of Scientific and Technical Information of China (English)

    杨仲言

    1994-01-01

    There′s new alloy that apparently just won′t give up. When a pin was scraped along it the equivalent of one million times, the alloy-made of zirconium, palladium, and ruthenium—displayed no net loss of surface material. When astonished researchers at the National Institute of Standards and Technology(NIST) persevered with a five-million-cycle wear test, they got the same result.

  5. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  6. 高速成型车削镍基合金Inconel 718的建模和有限元分析%Model and FEM of High - speed Form Turning Nickel Based on Alloy Inconel 718

    Institute of Scientific and Technical Information of China (English)

    杨军; 陈鸣; 陈云; 刘洪; 李发强; 谢勇

    2012-01-01

    The study simulates high speed turning of Inconel 718 forming cutting by software Deform 3D,then analyses the cutting forces, chip shape under different cutting depth process condition and the stress and wear of cutting tool .%利用Deform 3D有限元分析软件,模拟成型车削Inconel 718,分析了不同切削深度和切削速度下的切削力及卷屑排屑状况,并对刀具应力及刀具磨损进行了分析.

  7. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    OpenAIRE

    Xuming Zhang; Guosong Wu; Xiang Peng; Limin Li; Hongqing Feng; Biao Gao; Kaifu Huo; Chu, Paul K.

    2015-01-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface c...

  8. TEM microstructure of mechanically alloyed Ti-12Mg powders

    Institute of Scientific and Technical Information of China (English)

    T. S. KIM; B. T. LEE; J. P. AHN; J. K. PARK; J. C. BAE

    2006-01-01

    The microstructures of mechanical alloyed(MA) Ti-12%Mg alloy powders were examined using a high resolution TEM (HRTEM). The effect of MA atmospheres such as argon gas and liquid isopropyl alcohol on the resultant microstructure was investigated. Both the MA powders form a homogeneous Ti-Mg solid solution, but the oxidation behavior is distinguished. The phase change was studied as a function of milling conditions and annealing temperatures.

  9. Metallurgical Characterization of Superplastic Forming

    Science.gov (United States)

    1980-09-01

    The trans - formation of constant-crosshead-speed stress-strain curves into constant-strain- rate curves is clearly not satisfactory because it is based...MILL-ANNEALED AND SUPERPLASTICALLY- FORMED CONDITIONS; FORMING TEMPERATURE - 949EPC (17400F). 01"tln Stoi rte yeld grasa Ultimate l to oret~lSri as...1975), p. 163. 7. G. Rai and N. J. Grant, "On the Measurermients of Superplasticity in an Al-Cu Alloy," Met. Trans . 6A, 385 (1975). 8. A. K, Mukherjee

  10. Impact of the De-Alloying Kinetics and Alloy Microstructure on the Final Morphology of De-Alloyed Meso-Porous Metal Films

    Directory of Open Access Journals (Sweden)

    Bao Lin

    2014-10-01

    Full Text Available Nano-textured porous metal materials present unique surface properties due to their enhanced surface energy with potential applications in sensing, molecular separation and catalysis. In this paper, commercial alloy foils, including brass (Cu85Zn15 and Cu70Zn30 and white gold (Au50Ag50 foils have been chemically de-alloyed to form nano-porous thin films. The impact of the initial alloy micro-structure and number of phases, as well as chemical de-alloying (DA parameters, including etchant concentration, time and solution temperature on the final nano-porous thin film morphology and properties were investigated by electron microscopy (EM. Furthermore, the penetration depth of the pores across the alloys were evaluated through the preparation of cross sections by focus ion beam (FIB milling. It is demonstrated that ordered pores ranging between 100 nm and 600 nm in diameter and 2–5 μm in depth can be successfully formed for the range of materials tested. The microstructure of the foils were obtained by electron back-scattered diffraction (EBSD and linked to development of pits across the material thickness and surface during DA. The role of selective etching of both noble and sacrificial metal phases of the alloy were discussed in light of the competitive surface etching across the range of microstructures and materials tested.

  11. Oxidation Control and Non-equilibrium Phase Formation in Cu-Cr Alloys during Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    Xiaolong CUI; Lai WANG; Min QI

    2001-01-01

    Using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and optical microscopy, phase transformation of Cu-Cr alloys with various compositions during mechanical alloying process has been investigated. Besides the formation of supersaturated solid solution, the results show that a kind of amorphous oxide formed in the process,and the addition of carbon has obviously effect on the suppression of oxidation and the deoxidization of oxide. The reactive milling has a remarkable effect on the behavior of oxidation.

  12. Containerless Solidification and Characterization of Industrial Alloys (NEQUISOL)

    Science.gov (United States)

    Ilbagi, A.; Henein, H.; Chen, J.; Herlach, D. M.; Lengsdorf, R.; Gandin, Ch-A.; Tourret, D.; Garcia-Escorial, A.

    2011-12-01

    Containerless solidification using electromagnetic levitator (EML), gas atomization and an instrumented drop tube, known as impulse atomization is investigated for Al-Fe and Al-Ni alloys. The effects of primary phase and eutectic undercooling on the microstructure of Al-Fe alloys are investigated using the impulse drop tube and parabolic flight. The TEM characterization on the eutectic microstructure of impulse-atomized Al-Fe powders with two compositions showed that the metastable AlmFe formed in these alloys. Also, the growth undercooling that the dendritic front experiences during the solidification of the droplet resulted in variation of dendrite growth direction from to . For Al-4 at%Fe, it was found that in reduced-gravity and in the impulse-atomized droplets the primary intermetallic forms with a flower-like morphology, whereas in the terrestrial EML sample it has a needle like morphology. For Al-Ni, the effect of primary phase undercooling on dendrite growth velocity under terrestrial and reduced-gravity condition is discussed. It is shown that under terrestrial conditions, in the Ni-rich alloys with increasing undercooling the growth velocity increases, whereas in the Al-rich alloys the growth velocity decreases. However, the Al-rich alloy that was studied in reduced-gravity showed similar behavior to that of Ni-rich alloys. Furthermore, the effect of cooling rate on the phase fractions and metastable phase formation of impulse-atomized Al-Ni alloys is compared with EML. A microsegregation model for the solidification of Al-Ni alloys is applied to impulse atomized powders. The model accounts for the occurrence of several phase transformations, including one or several peritectic reactions and one eutectic reaction.

  13. Medium-Range Order Structure and Fragility of Superheated Melts of Amorphous CuHf Alloys

    Institute of Scientific and Technical Information of China (English)

    BIAN Xiu-Fang; SUN Bao-An; HU Li-Na

    2006-01-01

    @@ The structural factors of amorphous CuHf alloys at different temperatures are determined by using a high temperature x-ray diffractometer. It is found that not only the short-range order structure but also the medium-range order structure exists in amorphous CuHf alloys. The dynamic viscosities of CuHf alloy melts are measured by a torsional oscillation viscometer. The fragility of superheated melts of CuHf alloys is calculated based on the viscosity data. The experimental results show that the glass-forming ability of the CuHf alloys is closely related to the fragility of their superheated melt. The relationship between the medium-range order structures and the fragility of superheated melts has also been established in amorphous CuHf alloys. In contrast to the fragility of supercooled liquids, the fragility of superheated liquids promises a better approach to reflecting the dynamics of glass forming liquids.

  14. Thermodynamic and surface properties of Sb-Sn and In-Sn liquid alloys

    Indian Academy of Sciences (India)

    B C Anusionwu

    2006-08-01

    The thermodynamic properties of Sb-Sn and In-Sn liquid alloys have been studied using the quasi-chemical model for compound forming binary alloys and that for simple regular alloys. The concentration fluctuation cc(0) and the Warren-Cowley short-range order parameter (1) were determined for the whole concentration range at a temperature of 770 K. The surface tensions of these liquid alloys were determined for the whole concentration range by using energetics determined from thermodynamic calculations. In all calculations, In{Sn manifested properties very close to alloys of ideal mixing, while Sb-Sn showed properties that are asymmetric about equiatomic composition. Our results suggest that a weak complex of the form SbSn2 could be present in the Sb-Sn alloy at a temperature of about 770 K.

  15. Positron annihilation studies on FeCrCoNi high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Abhaya, S., E-mail: sab@igcar.gov.in; Rajaraman, R.; Kalavathi, S.; Amarendra, G.

    2015-01-25

    Highlights: • Defect annealing in FeCrCoNi high entropy alloy is studied using positron lifetime and Doppler broadening. • Variation of positron lifetime with temperature show the annealing of defects beyond 770 K. • XRD shows that the alloy forms FCC solid solution and the phase remains stable even after annealing at 1373 K. • Recrystallization assisted grain growth occurs beyond 973 K. - Abstract: Defect annealing in FeCrCoNi high entropy alloy is studied using positron lifetime and Doppler broadening spectroscopic techniques. Variation of positron lifetime with temperature show the annealing of defects beyond 770 K. Theoretical positron lifetime and electron momentum distributions were computed for the alloy to understand the nature of defects present in the arc melted alloy. X-ray diffraction measurements show that the arc melted alloy forms FCC solid solution and the phase remains stable even after annealing at 1373 K. Recrystallization assisted grain growth occurs beyond 973 K.

  16. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan;

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  17. Metal Alloy Compositions And Process Background Of The Invention

    Science.gov (United States)

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  18. Potential of an Al-Ti-MgAl2O4 Master Alloy and Ultrasonic Cavitation in the Grain Refinement of a Cast Aluminum Alloy

    Science.gov (United States)

    Sreekumar, V. M.; Babu, N. H.; Eskin, D. G.

    2017-02-01

    A new grain refining master alloy containing MgAl2O4 and Ti was synthesized by in situ reaction of TiO2 particles in an Al-Mg melt. MgAl2O4 particles formed were distributed in the melt by ultrasonic cavitation processing. The obtained master alloy showed considerable (50 pct) grain refining ability in a commercial A357-type Al-Si alloy. Ultrasonication contributed further to 25 pct in the grain refinement. In comparison with a commercial Al-5 pct Ti-1 pct B master alloy, the efficiency of the new master alloy is less at a lower addition rate. Nevertheless, both master alloys performed similarly at higher additions. The strength and ductility of the inoculated and ultrasonicated alloy showed at least a 10 pct and a 50 pct increase, respectively, as compared with non-grain-refined alloy and a similar mechanical performance in comparison with the alloy inoculated with Al-5 pct Ti-1 pct B master alloy.

  19. XPS study of the corrosion resisting composite alloying layer obtained by double glow plasma with the brush plating Ni interlayer

    Institute of Scientific and Technical Information of China (English)

    Jiang Xu; Xishan Xie; Zhong Xu; Wenjin Liu

    2004-01-01

    The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brush plating Ni interlayer on the low carbon steel substrate has been investigated. By the electrochemical method in 3.5% (mass fraction) NaC1 solution, the corrosion resistance of the composite alloying layer and single alloying layer is determined. The experimental results show that the corrosion resistance of the composite alloying layer is obviously better than that of the single alloying layer. The structure and composition of passive films formed on the two kinds of alloyed layers after electrochemical tests in 3.5% NaC1 solution have been studied using X-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloying of low carbon steel with the electric brush plating Ni interlayer is an appropriate technique to enhance the corrosion resistance compared with the single double glow surface alloying.

  20. Study of Titanizing the Surface of Copper Substrates by the Double Glow Discharge Plasma Surface Alloying Technique

    Institute of Scientific and Technical Information of China (English)

    Zhang Yuefei; Chen Fei; Lü Junxia; Su Yongan; Xu Zhong

    2005-01-01

    This paper discusses a study in which Ti surface alloying has been performed on copper substrates by means of a double glow discharge plasma surface alloying technique. The micro-structure, the phase structure, the micro-hardness and the distribution of Ti concentration of alloying layer were investigated in detail by XRD, SEM and so on. The effect of process parameters on the alloying layer was studied. The experimental results show that a Ti solid solution with the precipitation Cu4Ti alloying layer has been formed on the copper surface. The thickness of the alloying layer is about 120μm and the surface titanium concentration gradually decreases from w (Ti) = 87% to w (Ti) = 4%. The micro-hardness of the alloying layer is between 300 HV ~ 800 HV. Source sputtering, surface absorption, ion bombarding and high temperature diffusion are the major factors that affect the alloying layer.